test(deployment): cover Remote Host Download to… wiring (#2763)

Covers Download to… in the Remote Host view: the Project view selection preselects the folder picker (its parent folder for a selected file), cancelling the picker downloads nothing, and the chosen folder receives the remote paths.

Co-authored-by: GGVidal <[email protected]>

.oxfmtrc.json

@@ -12,6 +12,7 @@
     "src/editor/core/cm/angular/parser*.ts",
     "src/editor/core/cm/jsp/parser*.ts",
     "src/editor/core/cm/astro/parser*.ts",
+    "src/editor/core/cm/django/parser*.ts",
     "plugins/themes.md",
     "pnpm-lock.yaml",
     "**/*.toml",

Cargo.lock

@@ -4618,6 +4618,7 @@ name = "ide-lsp"
 version = "0.1.42"
 dependencies = [
  "dunce",
+ "encoding_rs",
  "futures",
  "globset",
  "ide-core",

crates/ide-agent/src/lib.rs

@@ -1338,15 +1338,19 @@ impl AgentManager {
     /// Files the task changed since it started.
     pub async fn changes(&self, id: &str) -> IdeResult<Vec<AgentChange>> {
         let task = self.task(id)?;
-        let (cwd, base) = task.cwd_and_base();
+        let at = task.base();
         let before = task.state.lock().before.clone();
-        blocking(move || Ok(worktree::without_untouched(worktree::changes(&cwd, &base)?, &before))).await
+        blocking(move || at.changes(&before)).await
     }
 
     /// Content of `path` (in the task's directory) when the task started.
     pub async fn base_text(&self, id: &str, path: PathBuf) -> IdeResult<Option<String>> {
-        let (cwd, base) = self.task(id)?.cwd_and_base();
-        blocking(move || worktree::file_at(&cwd, &path, &base)).await
+        let at = self.task(id)?.base();
+        blocking(move || match at.rev()? {
+            Some(rev) => worktree::file_at(at.cwd(), &path, &rev),
+            None => Ok(None),
+        })
+        .await
     }
 
     /// Rollback: puts the task's changed files among `rel_paths` (all with `None`) back as they
@@ -1356,16 +1360,17 @@ impl AgentManager {
         if task.state.lock().busy {
             return Err(IdeError::invalid("the agent is working: stop it before rolling back its changes"));
         }
-        let (cwd, base) = task.cwd_and_base();
+        let at = task.base();
         let (before, saved) = {
             let s = task.state.lock();
             (s.before.clone(), s.saved.as_ref().map(|name| self.shared.paths.store_dir.join(name)))
         };
         let restamped = blocking(move || {
-            let changes = worktree::without_untouched(worktree::changes(&cwd, &base)?, &before);
+            let changes = at.changes(&before)?;
+            let rev = at.rev()?;
             let mut restamped = Vec::new();
             for change in changes.iter().filter(|c| rel_paths.as_ref().is_none_or(|p| p.contains(&c.rel_path))) {
-                worktree::restore(&cwd, &base, change, &before, saved.as_deref())?;
+                worktree::restore(at.cwd(), rev.as_deref(), change, &before, saved.as_deref())?;
                 // Back to the user's own edits: not a change of the task any more.
                 if before.contains_key(&change.rel_path) {
                     restamped.push((change.rel_path.clone(), worktree::stamp(&change.path.0)));
@@ -1469,15 +1474,15 @@ impl Task {
         })
     }
 
-    fn cwd_and_base(&self) -> (PathBuf, String) {
+    fn base(&self) -> worktree::TaskBase {
         let s = self.state.lock();
-        // In the project's own checkout the user commits too: compare against the current HEAD,
-        // as the Commit tool window does, so commits made since the task started drop out.
-        let base = match s.task.isolation {
-            Isolation::Local => None,
-            Isolation::Worktree => s.task.base_commit.clone(),
-        };
-        (s.task.cwd.0.clone(), base.unwrap_or_else(|| "HEAD".into()))
+        let cwd = s.task.cwd.0.clone();
+        match s.task.isolation {
+            Isolation::Local => worktree::TaskBase::Local { cwd, start: s.task.base_commit.clone() },
+            Isolation::Worktree => {
+                worktree::TaskBase::Worktree { cwd, base: s.task.base_commit.clone().unwrap_or_else(|| "HEAD".into()) }
+            }
+        }
     }
 
     fn emit_task(&self) {

crates/ide-agent/src/tests.rs

@@ -2869,6 +2869,158 @@ async fn rolling_back_restores_the_start_of_the_task_and_keeps_the_users_own_edi
     assert!(!dir.join("store").join(format!("{}.before", task.id)).exists());
 }
 
+/// A git repository in a temporary folder, for local tasks whose checkout moves under them.
+struct Checkout {
+    _tmp: tempfile::TempDir,
+    dir: PathBuf,
+}
+
+impl Checkout {
+    fn new() -> Self {
+        let tmp = tempfile::tempdir().unwrap();
+        let dir = dunce::canonicalize(tmp.path()).unwrap();
+        let checkout = Self { _tmp: tmp, dir };
+        checkout.git(&["init", "-q", "-b", "main"]);
+        checkout.git(&["config", "core.autocrlf", "false"]);
+        checkout.write(".gitignore", "store/\nworktrees/\nagents/\nmodels.json\n");
+        checkout
+    }
+
+    fn git(&self, args: &[&str]) {
+        let ok = std::process::Command::new("git")
+            .args(["-c", "user.name=t", "-c", "user.email=t@t", "-c", "commit.gpgsign=false"])
+            .args(args)
+            .current_dir(&self.dir)
+            .status()
+            .unwrap()
+            .success();
+        assert!(ok, "{args:?}");
+    }
+
+    fn commit(&self, message: &str) {
+        self.git(&["add", "."]);
+        self.git(&["commit", "-q", "-m", message]);
+    }
+
+    fn write(&self, rel: &str, text: &str) {
+        std::fs::write(self.dir.join(rel), text).unwrap();
+    }
+
+    fn read(&self, rel: &str) -> String {
+        std::fs::read_to_string(self.dir.join(rel)).unwrap()
+    }
+
+    /// A local task, stopped so it can be rolled back.
+    async fn task(&self) -> (AgentManager, AgentTask) {
+        let mgr = manager(&self.dir, Arc::new(FakeAgent::default()));
+        let task = mgr
+            .create(NewAgentTask {
+                project_root: None,
+                prompt: text("Hello"),
+                provider: "claude".into(),
+                config: Vec::new(),
+                isolation: Isolation::Local,
+                base: None,
+            })
+            .await
+            .unwrap();
+        wait_for(&mgr, &task.id, AgentStatus::NeedsInput).await;
+        mgr.cancel(&task.id, None).unwrap();
+        wait_for(&mgr, &task.id, AgentStatus::Ready).await;
+        (mgr, task)
+    }
+}
+
+async fn changed(mgr: &AgentManager, id: &str) -> Vec<String> {
+    mgr.changes(id).await.unwrap().into_iter().map(|c| c.rel_path).collect()
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn work_uncommitted_by_a_reset_during_a_local_task_is_not_rolled_back() {
+    let repo = Checkout::new();
+    repo.write("a.txt", "base\n");
+    repo.write("mine.txt", "base\n");
+    repo.commit("init");
+    repo.write("mine.txt", "my work\n");
+    repo.commit("my work");
+    let (mgr, task) = repo.task().await;
+    repo.write("a.txt", "agent\n");
+    // The user takes the last commit back into the working tree (`git reset --soft`, an
+    // undone commit): its changes are the user's, not the agent's.
+    repo.git(&["reset", "-q", "--soft", "HEAD~1"]);
+    assert_eq!(changed(&mgr, &task.id).await, ["a.txt"]);
+
+    let base = mgr.base_text(&task.id, repo.dir.join("a.txt")).await.unwrap();
+    assert_eq!(base.as_deref(), Some("base\n"));
+    mgr.rollback_changes(&task.id, None).await.unwrap();
+    assert_eq!(repo.read("a.txt"), "base\n");
+    assert_eq!(repo.read("mine.txt"), "my work\n", "the user's work survives the rollback");
+    assert!(changed(&mgr, &task.id).await.is_empty());
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn a_branch_switched_to_during_a_local_task_is_left_alone() {
+    let repo = Checkout::new();
+    repo.write("a.txt", "base\n");
+    repo.write("other.txt", "base\n");
+    repo.commit("init");
+    repo.git(&["checkout", "-q", "-b", "feature"]);
+    repo.write("other.txt", "feature\n");
+    repo.write("only-feature.txt", "feature\n");
+    repo.commit("feature");
+    repo.git(&["checkout", "-q", "main"]);
+    repo.write("only-main.txt", "main\n");
+    repo.commit("main");
+    let (mgr, task) = repo.task().await;
+    repo.write("a.txt", "agent\n");
+    // The agent's uncommitted edit comes along to a branch that doesn't contain the task's start.
+    repo.git(&["checkout", "-q", "feature"]);
+    assert_eq!(changed(&mgr, &task.id).await, ["a.txt"]);
+
+    mgr.rollback_changes(&task.id, None).await.unwrap();
+    assert_eq!(repo.read("a.txt"), "base\n");
+    assert_eq!(repo.read("other.txt"), "feature\n");
+    assert_eq!(repo.read("only-feature.txt"), "feature\n");
+    assert!(!repo.dir.join("only-main.txt").exists());
+    assert!(changed(&mgr, &task.id).await.is_empty());
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn commits_made_during_a_local_task_are_kept_by_its_rollback() {
+    let repo = Checkout::new();
+    repo.write("a.txt", "base\n");
+    repo.commit("init");
+    let (mgr, task) = repo.task().await;
+    repo.write("a.txt", "agent\n");
+    repo.write("b.txt", "agent\n");
+    // The user commits what the agent did to `a.txt` so far: it drops out of the task's changes.
+    repo.git(&["add", "a.txt"]);
+    repo.git(&["commit", "-q", "-m", "keep"]);
+    assert_eq!(changed(&mgr, &task.id).await, ["b.txt"]);
+    repo.write("a.txt", "agent\nagain\n");
+    assert_eq!(changed(&mgr, &task.id).await, ["a.txt", "b.txt"]);
+
+    mgr.rollback_changes(&task.id, None).await.unwrap();
+    assert_eq!(repo.read("a.txt"), "agent\n", "back to the commit, not to before it");
+    assert!(!repo.dir.join("b.txt").exists());
+    assert!(changed(&mgr, &task.id).await.is_empty());
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn a_local_task_in_a_repository_without_commits_lists_and_rolls_back_its_changes() {
+    let repo = Checkout::new();
+    repo.write("mine.txt", "mine\n");
+    let (mgr, task) = repo.task().await;
+    repo.write("new.txt", "agent\n");
+    assert_eq!(changed(&mgr, &task.id).await, ["new.txt"]);
+    assert_eq!(mgr.base_text(&task.id, repo.dir.join("new.txt")).await.unwrap(), None);
+
+    mgr.rollback_changes(&task.id, None).await.unwrap();
+    assert!(!repo.dir.join("new.txt").exists());
+    assert_eq!(repo.read("mine.txt"), "mine\n");
+    assert!(changed(&mgr, &task.id).await.is_empty());
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn security_policy_auto_approves_whitelist_and_rejects_blacklist() {
     use ide_core::settings::AgentSecuritySettings;

crates/ide-agent/src/worktree.rs

@@ -117,14 +117,92 @@ pub(crate) fn changes(cwd: &Path, base: &str) -> IdeResult<Vec<AgentChange>> {
     let tracked: std::collections::HashSet<String> = out.iter().map(|c| c.rel_path.clone()).collect();
     for s in repo.status()? {
         if s.unstaged == Some(ChangeKind::Untracked) && !tracked.contains(&s.rel_path) {
-            let added = std::fs::read_to_string(&*s.path).map_or(0, |t| t.lines().count() as u32);
-            out.push(AgentChange { path: s.path, rel_path: s.rel_path, kind: ChangeKind::Added, added, removed: 0 });
+            out.push(added(s.path, s.rel_path));
         }
     }
     out.sort_by(|a, b| a.rel_path.cmp(&b.rel_path));
     Ok(out)
 }
 
+fn added(path: IpcPath, rel_path: String) -> AgentChange {
+    let added = std::fs::read_to_string(&*path).map_or(0, |t| t.lines().count() as u32);
+    AgentChange { path, rel_path, kind: ChangeKind::Added, added, removed: 0 }
+}
+
+/// Where a task works and what its changes are measured against.
+pub(crate) enum TaskBase {
+    /// A worktree of its own: everything since the commit it was created from, the agent's
+    /// own commits included.
+    Worktree { cwd: PathBuf, base: String },
+    /// The project's checkout, where the user works and commits too. `start` is the commit it
+    /// started from (`None` in a repository without commits, or an imported session).
+    Local { cwd: PathBuf, start: Option<String> },
+}
+
+impl TaskBase {
+    pub(crate) fn cwd(&self) -> &Path {
+        match self {
+            Self::Worktree { cwd, .. } | Self::Local { cwd, .. } => cwd,
+        }
+    }
+
+    /// The files the task changed, less those changed before it started and untouched since.
+    pub(crate) fn changes(&self, before: &BTreeMap<String, Stamp>) -> IdeResult<Vec<AgentChange>> {
+        let (cwd, start) = match self {
+            Self::Worktree { cwd, base } => return Ok(without_untouched(changes(cwd, base)?, before)),
+            Self::Local { cwd, start } => (cwd, start.as_deref()),
+        };
+        let Some(repo) = discover(cwd)? else { return Ok(Vec::new()) };
+        // What is uncommitted, as the Commit tool window lists it: commits made since the task
+        // started drop out.
+        let head = repo.branch_info()?.head_commit;
+        let listed = match &head {
+            Some(head) => changes(cwd, head)?,
+            None => {
+                let mut all: Vec<AgentChange> = repo
+                    .status()?
+                    .into_iter()
+                    .filter(|s| s.path.is_file())
+                    .map(|s| added(s.path, s.rel_path))
+                    .collect();
+                all.sort_by(|a, b| a.rel_path.cmp(&b.rel_path));
+                all
+            }
+        };
+        let listed = without_untouched(listed, before);
+        let Some(start) = start.filter(|s| head.as_deref() != Some(*s)) else { return Ok(listed) };
+        // HEAD moved (a reset, a checkout, a pull): a file that is as it was when the task
+        // started is the user's doing, not the task's.
+        Ok(listed
+            .into_iter()
+            .filter(|c| {
+                before.contains_key(&c.rel_path)
+                    || !repo.file_bytes_at(&c.path.0, Some(start)).is_ok_and(|at| at == std::fs::read(&c.path.0).ok())
+            })
+            .collect())
+    }
+
+    /// The revision the task's changed files go back to on rollback, and are compared with:
+    /// the commit the task started from, or the current `HEAD` once the user committed on top
+    /// of it, so those commits stay. `None` while the repository has no commits.
+    pub(crate) fn rev(&self) -> IdeResult<Option<String>> {
+        let (cwd, start) = match self {
+            Self::Worktree { base, .. } => return Ok(Some(base.clone())),
+            Self::Local { cwd, start } => (cwd, start.as_deref()),
+        };
+        let Some(repo) = discover(cwd)? else { return Ok(None) };
+        let head = repo.branch_info()?.head_commit;
+        // A start commit git no longer knows (garbage-collected) can't be gone back to.
+        let start = start.filter(|s| repo.merge_base(s, s).ok().flatten().is_some());
+        Ok(match (start, head) {
+            (Some(start), Some(head)) if start != head && repo.merge_base(start, &head)?.as_deref() != Some(start) => {
+                Some(start.to_owned())
+            }
+            (start, head) => head.or_else(|| start.map(str::to_owned)),
+        })
+    }
+}
+
 /// Copies the task's `changes` (against `base`) from the worktree `cwd` into the
 /// local checkout `root`, uncommitted: the user reviews and commits them with the
 /// VCS tools. Files the checkout changed itself are left alone and reported, so
@@ -220,11 +298,11 @@ pub(crate) fn save_before(cwd: &Path, before: &BTreeMap<String, Stamp>, dir: &Pa
 }
 
 /// Rolls `change` back: to the copy saved when the task started when the file had changes
-/// then (`before`, `saved` holding the copies), otherwise to `base` (removed when `base`
-/// lacks it).
+/// then (`before`, `saved` holding the copies), otherwise to `rev` (removed when `rev` lacks
+/// it, or when there is no `rev`: the repository had no commits).
 pub(crate) fn restore(
     cwd: &Path,
-    base: &str,
+    rev: Option<&str>,
     change: &AgentChange,
     before: &BTreeMap<String, Stamp>,
     saved: Option<&Path>,
@@ -242,10 +320,13 @@ pub(crate) fn restore(
                 })?;
             Some(std::fs::read(copy)?)
         }
-        None => {
-            let repo = Repo::discover(cwd)?.ok_or_else(|| IdeError::invalid("not in a git repository"))?;
-            repo.file_bytes_at(path, Some(base))?
-        }
+        None => match rev {
+            Some(rev) => {
+                let repo = Repo::discover(cwd)?.ok_or_else(|| IdeError::invalid("not in a git repository"))?;
+                repo.file_bytes_at(path, Some(rev))?
+            }
+            None => None,
+        },
     };
     match content {
         Some(bytes) => {
@@ -490,6 +571,39 @@ mod tests {
         assert_eq!(again.accepted, ["a.txt", "gone.txt", "new.txt"]);
     }
 
+    #[test]
+    fn a_local_task_goes_back_to_its_start_unless_the_user_committed_on_top_of_it() {
+        let tmp = tempfile::tempdir().unwrap();
+        let repo = tmp.path().join("repo");
+        std::fs::create_dir(&repo).unwrap();
+        git(&repo, &["init", "-q", "-b", "main"]);
+        let local = |start: Option<&str>| TaskBase::Local { cwd: repo.clone(), start: start.map(str::to_owned) };
+        let head = || head_of(&repo).unwrap().1;
+        let commit = |name: &str| {
+            std::fs::write(repo.join(name), "x\n").unwrap();
+            git(&repo, &["add", "."]);
+            git(&repo, &["commit", "-q", "-m", name]);
+            head_of(&repo).unwrap().1
+        };
+
+        assert_eq!(local(None).rev().unwrap(), None, "no commits yet");
+        let first = commit("a.txt");
+        assert_eq!(local(None).rev().unwrap(), Some(first.clone()), "an imported session: HEAD");
+        let start = commit("b.txt");
+        assert_eq!(local(Some(&start)).rev().unwrap(), Some(start.clone()), "HEAD where it started");
+        let ahead = commit("c.txt");
+        assert_eq!(local(Some(&start)).rev().unwrap(), Some(ahead), "committed on top: HEAD");
+        git(&repo, &["reset", "-q", "--soft", &first]);
+        assert_eq!(local(Some(&start)).rev().unwrap(), Some(start.clone()), "moved back: the start");
+        git(&repo, &["checkout", "-q", "-b", "side"]);
+        commit("d.txt");
+        assert_eq!(local(Some(&start)).rev().unwrap(), Some(start.clone()), "another branch: the start");
+        let gone = "0123456789abcdef0123456789abcdef01234567";
+        assert_eq!(local(Some(gone)).rev().unwrap(), Some(head()), "an unknown start: HEAD");
+        let worktree = TaskBase::Worktree { cwd: repo.clone(), base: start.clone() };
+        assert_eq!(worktree.rev().unwrap(), Some(start));
+    }
+
     #[test]
     fn accept_leaves_files_the_checkout_changed_itself() {
         let (_tmp, repo, created) = accept_repo();

crates/ide-core/src/ipc_path.rs

@@ -12,11 +12,16 @@ use std::path::{Path, PathBuf};
 
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
 
-/// `p` as the UI sees it: `C:\a\b` and `\\?\C:\a\b` become `C:/a/b`.
+/// `p` as the UI sees it: `C:\a\b`, `c:\a\b` and `\\?\C:\a\b` become `C:/a/b`.
 pub fn to_ipc(p: &Path) -> String {
     #[cfg(windows)]
     {
-        dunce::simplified(p).to_string_lossy().replace('\\', "/")
+        let mut s = dunce::simplified(p).to_string_lossy().replace('\\', "/");
+        // The UI compares path strings; a drive letter is case-insensitive.
+        if s.as_bytes().get(1) == Some(&b':') {
+            s[..1].make_ascii_uppercase();
+        }
+        s
     }
     #[cfg(not(windows))]
     {
@@ -144,5 +149,8 @@ mod tests {
         assert_eq!(to_ipc(Path::new(r"\\?\C:\a\b")), "C:/a/b");
         assert_eq!(to_ipc(&Path::new("C:/a").join("b")), "C:/a/b");
         assert_eq!(serde_json::to_string(&IpcPath::from(r"C:\a\b")).unwrap(), r#""C:/a/b""#);
+        assert_eq!(to_ipc(Path::new(r"c:\a\b")), "C:/a/b");
+        assert_eq!(to_ipc(Path::new(r"\\?\d:\a")), "D:/a");
+        assert_eq!(to_ipc(Path::new(r"\\server\share\a")), "//server/share/a");
     }
 }

crates/ide-core/src/text.rs

@@ -138,8 +138,11 @@ impl WorkspaceEdit {
                         continue;
                     }
                     *expected = expected.or(version);
+                    // Repeats within one entry are intended (LSP inserts at one position
+                    // apply in order); only an alias entry repeats what is already merged.
+                    let merged = own.len();
                     for edit in edits {
-                        if !own.contains(&edit) {
+                        if !own[..merged].contains(&edit) {
                             own.push(edit);
                         }
                     }
@@ -277,10 +280,40 @@ pub struct OutlineItem {
 /// Fuzzy-match highlight: indices (in chars of the displayed string) that matched.
 pub type MatchIndices = Vec<u32>;
 
-#[cfg(all(test, unix))]
+#[cfg(test)]
 mod workspace_edit_tests {
     use super::*;
 
+    #[test]
+    fn repeated_edits_within_one_entry_survive_but_repeats_across_entries_do_not() {
+        let path = PathBuf::from("missing-dir/main.ts");
+        let at = |line, text: &str| TextEdit {
+            range: Range::new(Pos::new(line, 0), Pos::new(line, 0)),
+            new_text: text.into(),
+        };
+        let entry = |edits: Vec<TextEdit>| FileEdit::Edit { path: path.clone().into(), edits, version: None };
+        let (nl, brace, other) = (at(0, "\n"), at(1, "}"), at(2, "x"));
+        for (entries, expected) in [
+            (vec![vec![nl.clone(), nl.clone()]], vec![nl.clone(), nl.clone()]),
+            (vec![vec![brace.clone(), nl.clone(), brace.clone()]], vec![brace.clone(), nl.clone(), brace.clone()]),
+            (vec![vec![nl.clone(), nl.clone()], vec![nl.clone(), nl.clone()]], vec![nl.clone(), nl.clone()]),
+            (vec![vec![nl.clone()], vec![nl.clone(), other.clone()]], vec![nl.clone(), other.clone()]),
+            (
+                vec![vec![nl.clone()], vec![other.clone(), other.clone()]],
+                vec![nl.clone(), other.clone(), other.clone()],
+            ),
+        ] {
+            let mut workspace =
+                WorkspaceEdit { files: entries.clone().into_iter().map(entry).collect(), ..Default::default() };
+            workspace.deduplicate();
+            assert_eq!(workspace.files, [entry(expected.clone())], "{entries:?}");
+            let once = workspace.clone();
+            workspace.deduplicate();
+            assert_eq!(workspace, once, "{entries:?}");
+        }
+    }
+
+    #[cfg(unix)]
     #[test]
     fn aliases_are_one_edit_but_resource_operations_preserve_order() {
         let dir = tempfile::tempdir().unwrap();

crates/ide-dap/src/lib.rs

@@ -621,9 +621,9 @@ fn step_settled(session: &Session, sent: Result<Value, DapError>) -> Result<Valu
     sent
 }
 
-/// Delve compiles the debuggee to `__debug_bin` in the session's cwd (on Windows
-/// `__debug_bin.exe` plus `__debug_bin.exe<digits>` in DAP mode) and removes it on a
-/// graceful exit — a shutdown it doesn't always reach, so the files pile up. Sweep
+/// Delve compiles the debuggee to `__debug_bin` in the session's cwd (in DAP mode a
+/// temp-file name, `__debug_bin<digits>`; on Windows with `.exe` before the digits) and
+/// removes it on a graceful exit — a shutdown it doesn't always reach, so the files pile up. Sweep
 /// the leftovers once the session is down. Runs after `session_closed`, so Delve
 /// has already exited or been killed and holds no file locks; a leftover of a
 /// still-building run is removed on that run's own shutdown.
@@ -632,14 +632,10 @@ fn remove_delve_binaries(cwd: &Path) {
     for entry in entries.flatten() {
         let name = entry.file_name();
         let Some(name) = name.to_str() else { continue };
-        // Windows writes `__debug_bin.exe` (and `.exe<digits>` in DAP mode); other
-        // platforms keep the bare name. Suffixes like `.go` are user files.
-        let suffix = name.strip_prefix("__debug_bin");
-        let leftover = suffix.is_some_and(|s| {
-            s.is_empty()
-                || s == ".exe"
-                || (s.starts_with(".exe") && s[".exe".len()..].chars().all(|c| c.is_ascii_digit()))
-        });
+        // `__debug_bin`, then `.exe` on Windows, then DAP mode's temp-file digits.
+        // Suffixes like `.go` are user files.
+        let suffix = name.strip_prefix("__debug_bin").map(|s| s.strip_prefix(".exe").unwrap_or(s));
+        let leftover = suffix.is_some_and(|s| s.chars().all(|c| c.is_ascii_digit()));
         if !leftover || entry.file_type().is_ok_and(|t| !t.is_file()) {
             continue;
         }

crates/ide-dap/src/tests.rs

@@ -1472,6 +1472,7 @@ fn godot_registry(port: u16, command: &str, args: &[&str]) -> Arc<LanguageRegist
         indent: None,
         ui_mode: None,
         framework_ui_modes: Vec::new(),
+        framework_files: Vec::new(),
         formatter: None,
         scratch_template: None,
         tree_sitter: None,
@@ -2095,20 +2096,20 @@ async fn stop_kills_the_program_started_by_the_reported_launcher() {
 fn delve_leftovers_are_removed_without_touching_other_files() {
     let dir = std::env::temp_dir().join(format!("openidea-delve-bin-{}", std::process::id()));
     std::fs::create_dir_all(&dir).unwrap();
-    for name in ["__debug_bin", "__debug_bin.exe", "__debug_bin.exe3323301925"] {
+    for name in ["__debug_bin", "__debug_bin833767175", "__debug_bin.exe", "__debug_bin.exe3323301925"] {
         std::fs::write(dir.join(name), b"bin").unwrap();
     }
     // Lookalikes that are not Delve's own binaries stay: sources, a future
     // in-progress build, and a directory that happens to share the name.
-    for name in ["__debug_bin.go", "__debug_bin.go.exe", "main.go"] {
+    for name in ["__debug_bin.go", "__debug_bin.go.exe", "__debug_bin12.go", "main.go"] {
         std::fs::write(dir.join(name), b"keep").unwrap();
     }
     std::fs::create_dir(dir.join("__debug_bin.dir")).unwrap();
     remove_delve_binaries(&dir);
-    for name in ["__debug_bin", "__debug_bin.exe", "__debug_bin.exe3323301925"] {
+    for name in ["__debug_bin", "__debug_bin833767175", "__debug_bin.exe", "__debug_bin.exe3323301925"] {
         assert!(!dir.join(name).exists(), "{name} should be gone");
     }
-    for name in ["__debug_bin.go", "__debug_bin.go.exe", "main.go", "__debug_bin.dir"] {
+    for name in ["__debug_bin.go", "__debug_bin.go.exe", "__debug_bin12.go", "main.go", "__debug_bin.dir"] {
         assert!(dir.join(name).exists(), "{name} should stay");
     }
     std::fs::remove_dir_all(&dir).unwrap();

crates/ide-host/src/ops/deploy.rs

@@ -169,6 +169,25 @@ pub async fn remote_rename(state: &Host, connection: FsConnection, from: String,
     state.remote.remote_rename(&connection, &from, &to).await
 }
 
+/// Remote Host › Download to…: remote files and folders into a local folder, each under its
+/// own name.
+pub async fn remote_download_into(
+    window: &str,
+    state: &Host,
+    connection: FsConnection,
+    paths: Vec<String>,
+    target: IpcPath,
+    request: RequestId,
+) -> IdeResult<TransferReport> {
+    let project = state.project(window)?;
+    let token = state.begin_request(request);
+    let (mut report, done) = progress(project.sink.clone(), "Downloading", token.clone());
+    let r = state.remote.download_into(&connection, &paths, &target, &token, &mut report).await;
+    done();
+    state.end_request(request);
+    r
+}
+
 pub async fn deploy_test_connection(state: &Host, connection: FsConnection, path: String) -> IdeResult<()> {
     state.remote.test_connection(&connection, &path).await
 }
@@ -197,6 +216,17 @@ pub(crate) fn register(d: &mut crate::rpc::Dispatcher) {
     d.add("remote_of", |c| async move { Ok(remote_of(&c.host, c.arg("path")?)) });
     d.add("remote_delete", |c| async move { remote_delete(&c.host, c.arg("connection")?, c.arg("path")?).await });
     d.add("remote_mkdir", |c| async move { remote_mkdir(&c.host, c.arg("connection")?, c.arg("path")?).await });
+    d.add("remote_download_into", |c| async move {
+        remote_download_into(
+            &c.window,
+            &c.host,
+            c.arg("connection")?,
+            c.arg("paths")?,
+            c.arg("target")?,
+            c.arg("request")?,
+        )
+        .await
+    });
     d.add("remote_rename", |c| async move {
         remote_rename(&c.host, c.arg("connection")?, c.arg("from")?, c.arg("to")?).await
     });

crates/ide-host/src/ops/doc/commands.rs

@@ -19,7 +19,17 @@ pub async fn blocking<T: Send + 'static>(f: impl FnOnce() -> IdeResult<T> + Send
 pub async fn doc_open_virtual(host: &Host, window: &str, uri: String) -> IdeResult<DocumentInfo> {
     let project = host.project(window)?;
     let vd = crate::ops::lsp::lsp_virtual_document(host, window, uri).await?;
-    blocking(move || project.documents.open_virtual(&vd.uri, vd.language_id, &vd.text)).await
+    blocking(move || {
+        project.documents.open_virtual(
+            &vd.uri,
+            vd.language_id,
+            &vd.text,
+            &vd.encoding,
+            vd.has_bom,
+            vd.can_reload_encoding,
+        )
+    })
+    .await
 }
 
 /// The CodeMirror mode `path` gets when opened (`DocumentInfo::ui_mode`),
@@ -30,6 +40,8 @@ pub async fn doc_ui_mode(host: &Host, window: &str, path: PathBuf) -> IdeResult<
 }
 
 /// "Reload with Encoding" (`reload`) or "Convert to Encoding"; returns the new encoding and BOM state.
+/// Virtual documents re-read their origin (archive, language server, Git blob)
+/// instead of a disk file; converting them would write to it, so it stays refused.
 pub async fn doc_set_encoding(
     host: &Host,
     window: &str,
@@ -38,6 +50,14 @@ pub async fn doc_set_encoding(
     reload: bool,
 ) -> IdeResult<DocumentEncoding> {
     let project = host.project(window)?;
+    if reload && let Some(uri) = project.documents.virtual_uri(doc)? {
+        let vd = if uri.starts_with("git-revision:") {
+            crate::ops::vcs::revision_virtual_document(host, window, &uri, Some(&encoding)).await?
+        } else {
+            project.lsp.reload_virtual(&uri, &encoding).await?
+        };
+        return host.blocking(move || project.documents.replace_virtual(doc, &vd.text, &vd.encoding, vd.has_bom)).await;
+    }
     host.blocking(move || project.documents.set_encoding(doc, &encoding, reload)).await
 }
 

crates/ide-host/src/ops/doc/tests.rs

@@ -176,8 +176,11 @@ async fn binary_and_virtual_documents_are_skipped() {
     std::fs::write(&path, b"\0\0binary payload").unwrap();
     let binary = f.open(&path).await;
     assert!(binary.read_only);
-    let virtual_doc =
-        f.project.documents.open_virtual("test://virtual", ide_core::LanguageId::plain_text(), "virtual").unwrap();
+    let virtual_doc = f
+        .project
+        .documents
+        .open_virtual("test://virtual", ide_core::LanguageId::plain_text(), "virtual", "utf-8", false, false)
+        .unwrap();
     std::fs::write(&path, "now ordinary text").unwrap();
     f.events.lock().clear();
     f.sync().await;

crates/ide-host/src/ops/lsp.rs

@@ -544,7 +544,7 @@ pub async fn lsp_goto_implementation(
 /// classes and disk class files. Cached per project.
 pub async fn lsp_virtual_document(host: &Host, window: &str, uri: String) -> IdeResult<VirtualDocument> {
     if uri.starts_with("git-revision:") {
-        return crate::ops::vcs::revision_virtual_document(host, window, &uri).await;
+        return crate::ops::vcs::revision_virtual_document(host, window, &uri, None).await;
     }
     host.project(window)?.lsp.virtual_document(&uri).await
 }

crates/ide-host/src/ops/vcs/commands.rs

@@ -20,10 +20,13 @@ struct LogAccess {
 }
 
 /// Immutable Git objects exposed through the editor's ordinary read-only VFS.
+/// `encoding` re-decodes the blob with it ("Reload with Encoding") instead of
+/// the project's detection.
 pub async fn revision_virtual_document(
     host: &Host,
     window: &str,
     uri: &str,
+    encoding: Option<&str>,
 ) -> IdeResult<ide_lsp::types::VirtualDocument> {
     #[derive(Deserialize)]
     struct Target {
@@ -47,7 +50,7 @@ pub async fn revision_virtual_document(
         .collect::<IdeResult<Vec<_>>>()?;
     let target: Target = serde_json::from_slice(&bytes).map_err(|e| ide_core::IdeError::invalid(e.to_string()))?;
     let path = target.repo.join(&target.path);
-    let text = vcs_file_at(host, window, path, Some(target.revision.clone()))
+    let (text, charset, has_bom) = revision_text(host, window, &path, &target.revision, encoding)
         .await?
         .ok_or_else(|| ide_core::IdeError::not_found("file is absent at this revision"))?;
     Ok(ide_lsp::types::VirtualDocument {
@@ -57,8 +60,63 @@ pub async fn revision_virtual_document(
         title: target.path.file_name().unwrap_or_default().to_string_lossy().into_owned(),
         description: Some(format!("{} · {}", target.repo.display(), target.revision)),
         decompiled: false,
+        encoding: charset.name().to_ascii_lowercase(),
+        has_bom,
+        can_reload_encoding: true,
     })
 }
+
+/// Revision text with the charset it was decoded with and whether a matching
+/// BOM was stripped; `None` when the file is absent at the revision.
+async fn revision_text(
+    host: &Host,
+    window: &str,
+    path: &Path,
+    rev: &str,
+    encoding: Option<&str>,
+) -> IdeResult<Option<(String, &'static encoding_rs::Encoding, bool)>> {
+    let project = host.project(window).ok();
+    let external = host.external_logs.read().get(host.owner_window(window)).and_then(|rs| {
+        rs.iter().filter(|r| path.starts_with(r.root())).max_by_key(|r| r.root().components().count()).cloned()
+    });
+    let (path, rev, encoding) = (path.to_path_buf(), rev.to_owned(), encoding.map(str::to_owned));
+    blocking(move || {
+        fn with_repo<T>(
+            project: &Option<std::sync::Arc<Project>>,
+            external: &Option<std::sync::Arc<ide_vcs::Repo>>,
+            path: &Path,
+            f: impl FnOnce(&ide_vcs::Repo) -> IdeResult<T>,
+        ) -> IdeResult<T> {
+            match project {
+                Some(project) => project.with_log_repo_of(path, f),
+                None => f(external
+                    .as_ref()
+                    .ok_or_else(|| ide_core::IdeError::unavailable("external Git log is not open"))?),
+            }
+        }
+        let (text_encoding, charset) = match &encoding {
+            Some(label) => {
+                let charset = encoding_rs::Encoding::for_label(label.trim().as_bytes())
+                    .ok_or_else(|| ide_core::IdeError::invalid(format!("unknown encoding {label:?}")))?;
+                (ide_vcs::TextEncoding::from(charset), charset)
+            }
+            None => match &project {
+                Some(project) => {
+                    let text_encoding = project.vcs_encoding(&path, Some(&rev))?;
+                    (text_encoding, text_encoding.charset)
+                }
+                None => (ide_vcs::TextEncoding::from(encoding_rs::UTF_8), encoding_rs::UTF_8),
+            },
+        };
+        let bytes = with_repo(&project, &external, &path, |r| r.file_bytes_at(&path, Some(&rev)))?;
+        let Some(bytes) = bytes else { return Ok(None) };
+        let has_bom = encoding_rs::Encoding::for_bom(&bytes).is_some_and(|(enc, _)| enc == charset);
+        let text =
+            with_repo(&project, &external, &path, |r| r.file_at(&path, Some(&rev), text_encoding))?.unwrap_or_default();
+        Ok(Some((text, charset, has_bom)))
+    })
+    .await
+}
 impl LogAccess {
     fn new(host: &Host, window: &str, at: Option<&Path>) -> Self {
         let project = host.project(window).ok();

crates/ide-host/src/project.rs

@@ -1231,7 +1231,7 @@ fn content_roots(settings: &ide_core::settings::Settings, root: &Path, build_cac
 
 /// The roots a file may navigate into: its own root (the workspace member containing it, or
 /// the project root) plus that root's configured dependencies. A workspace member depends
-/// only on the roots picked per member in Settings › Project Structure › Dependencies —
+/// only on the roots picked per member in Project Structure › Dependencies —
 /// being attached to the workspace never makes its code navigable by itself.
 /// Cached navigation roots per (project, file), with the instant they were computed.
 type NavigationRootsCache = HashMap<(PathBuf, PathBuf), (Instant, Vec<PathBuf>)>;

crates/ide-host/tests/external_log.rs

@@ -93,9 +93,15 @@ async fn external_history_is_readable_and_never_becomes_a_write_target() {
     let payload =
         serde_json::to_vec(&serde_json::json!({ "repo": external, "revision": first, "path": "deleted.txt" })).unwrap();
     let hex = payload.iter().map(|b| format!("{b:02x}")).collect::<String>();
-    let document =
-        vcs::revision_virtual_document(&host, "standalone", &format!("git-revision:{hex}/deleted.txt")).await.unwrap();
+    let uri = format!("git-revision:{hex}/deleted.txt");
+    let document = vcs::revision_virtual_document(&host, "standalone", &uri, None).await.unwrap();
     assert_eq!(document.text, "historical content\n");
+    assert_eq!(document.encoding, "utf-8");
+    assert!(document.can_reload_encoding);
+    // Reload with Encoding re-decodes the blob with the chosen charset.
+    let reloaded = vcs::revision_virtual_document(&host, "standalone", &uri, Some("utf-16le")).await.unwrap();
+    assert_eq!(reloaded.encoding, "utf-16le");
+    assert_ne!(reloaded.text, document.text);
     host.trust.decide(&root, true, false).unwrap();
     let project = host.open_project("main", &root).unwrap();
     assert!(vcs::vcs_log(&host, "main", Some(external.clone()), Default::default()).await.is_err());

crates/ide-host/tests/rpc.rs

@@ -330,6 +330,7 @@ async fn local_deployment_runs_on_the_project_host() {
         "remote_delete",
         "remote_mkdir",
         "remote_rename",
+        "remote_download_into",
         "db_sources",
         "db_save_sources",
         "db_set_password",

crates/ide-host/tests/trust.rs

@@ -94,6 +94,7 @@ async fn application_commands_work_in_restricted_projects_and_without_a_project(
         "remote_delete",
         "remote_mkdir",
         "remote_rename",
+        "remote_download_into",
         "remote_import_local",
         "remote_bootstrap_exec",
         "deploy_upload",

crates/ide-language/src/lib.rs

@@ -55,6 +55,10 @@ pub struct LanguageConfig {
     /// the first one whose root marker is found applies.
     #[serde(default)]
     pub framework_ui_modes: Vec<FrameworkUiMode>,
+    /// Files of this language in a framework's projects that their extension alone would
+    /// give to another language (Django templates are `.html` files in `templates`).
+    #[serde(default)]
+    pub framework_files: Vec<FrameworkFiles>,
     #[serde(default)]
     pub tree_sitter: Option<String>,
     #[serde(default)]
@@ -90,6 +94,18 @@ pub struct FrameworkUiMode {
     pub root_markers: Vec<String>,
 }
 
+/// Files in a framework's folder: a file with one of `extensions` below a folder named
+/// `folder`, which has a root marker in a directory above it.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub struct FrameworkFiles {
+    pub folder: String,
+    /// Without the dot, compared ignoring case.
+    pub extensions: Vec<String>,
+    /// Matched like language servers' `root-markers`, e.g. `manage.py`.
+    pub root_markers: Vec<String>,
+}
+
 #[derive(Clone, Copy, Debug, Serialize, Deserialize, Type)]
 #[serde(rename_all(serialize = "camelCase", deserialize = "kebab-case"))]
 pub struct IndentConfig {

crates/ide-language/src/registry.rs

@@ -22,6 +22,7 @@ const BUILTIN: &[(&str, &str)] = &[
     ("d", include_str!("../../../languages/d.toml")),
     ("dart", include_str!("../../../languages/dart.toml")),
     ("diff", include_str!("../../../languages/diff.toml")),
+    ("django-html", include_str!("../../../languages/django-html.toml")),
     ("dockerfile", include_str!("../../../languages/dockerfile.toml")),
     ("dotenv", include_str!("../../../languages/dotenv.toml")),
     ("elixir", include_str!("../../../languages/elixir.toml")),
@@ -371,14 +372,13 @@ impl LanguageRegistry {
             .map(|f| f.ui_mode.clone())
     }
 
-    /// Creating or removing `path` can change a file's `framework_ui_mode`:
-    /// it is a framework's root marker.
+    /// Creating or removing `path` can change a file's `framework_ui_mode` or its
+    /// language (`framework-files`): it is a framework's root marker.
     pub fn is_framework_marker(&self, path: &Path) -> bool {
-        self.state()
-            .languages
-            .iter()
-            .flat_map(|l| &l.framework_ui_modes)
-            .any(|f| f.root_markers.iter().any(|m| crate::markers::is_marker_path(path, m)))
+        let state = self.state();
+        let modes = state.languages.iter().flat_map(|l| &l.framework_ui_modes).map(|f| &f.root_markers);
+        let files = state.languages.iter().flat_map(|l| &l.framework_files).map(|f| &f.root_markers);
+        modes.chain(files).flatten().any(|m| crate::markers::is_marker_path(path, m))
     }
 
     /// Detects by Override File Type, exact file name, then file-name pattern
@@ -400,6 +400,9 @@ impl LanguageRegistry {
         if let Some((_, i)) = t.name_globs.iter().find(|(p, _)| wildcard_match(p, file_name)) {
             return languages[*i].id.clone();
         }
+        if let Some(l) = languages.iter().find(|l| l.framework_files.iter().any(|f| is_framework_file(f, path))) {
+            return l.id.clone();
+        }
         let lower = file_name.to_ascii_lowercase();
         let mut rest = lower.as_str();
         while let Some(dot) = rest.find('.') {
@@ -420,6 +423,19 @@ impl LanguageRegistry {
     }
 }
 
+/// `path` is one of `files`: its extension is listed, and the nearest folder above it named
+/// `files.folder` has a root marker in a directory above that folder.
+fn is_framework_file(files: &crate::FrameworkFiles, path: &Path) -> bool {
+    let Some(ext) = path.extension().and_then(|e| e.to_str()) else { return false };
+    if !files.extensions.iter().any(|e| e.eq_ignore_ascii_case(ext)) {
+        return false;
+    }
+    path.ancestors()
+        .skip(1)
+        .find(|dir| dir.file_name().is_some_and(|name| name == files.folder.as_str()))
+        .is_some_and(|folder| crate::marked_root(None, folder, &files.root_markers).is_some())
+}
+
 /// `*` matches any (possibly empty) run of characters, `?` exactly one; everything else is literal.
 fn wildcard_match(pattern: &str, name: &str) -> bool {
     let p: Vec<char> = pattern.chars().collect();
@@ -497,6 +513,7 @@ mod tests {
         "Brainfuck",
         "Cobol",
         "C#",
+        "Django Template",
         "Clojure",
         "ClojureScript",
         "Closure Stylesheets (GSS)",
@@ -801,6 +818,36 @@ mod tests {
         assert!(!reg.is_framework_marker(&root.join("apps/admin/package.json")));
     }
 
+    #[test]
+    fn django_projects_make_html_in_templates_folders_templates() {
+        let reg = reg();
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        let detect = |file: &str| reg.detect(&root.join(file), None).as_str().to_owned();
+        std::fs::create_dir_all(root.join("src/orders/templates/orders/email")).unwrap();
+        std::fs::create_dir_all(root.join("site/templates")).unwrap();
+        std::fs::write(root.join("src/manage.py"), "").unwrap();
+        assert_eq!(detect("src/orders/templates/orders/detail.html"), "django-html");
+        assert_eq!(detect("src/orders/templates/orders/email/body.TXT"), "django-html");
+        assert_eq!(detect("src/templates/base.html"), "django-html");
+        assert_eq!(detect("src/orders/templates/orders/data.json"), "json");
+        assert_eq!(detect("src/orders/static/orders/page.html"), "html");
+        // No `manage.py` above this `templates` folder.
+        assert_eq!(detect("site/templates/index.html"), "html");
+        assert_eq!(detect("page.djhtml"), "django-html");
+        assert!(reg.is_framework_marker(&root.join("src/manage.py")));
+    }
+
+    #[test]
+    fn the_django_fixture_has_templates_and_a_page() {
+        let reg = reg();
+        let fixture = Path::new(env!("CARGO_MANIFEST_DIR")).join("../../fixtures/django-app");
+        let detect = |file: &str| reg.detect(&fixture.join(file), None).as_str().to_owned();
+        assert_eq!(detect("shop/templates/shop/product_list.html"), "django-html");
+        assert_eq!(detect("shop/templates/shop/email/order.txt"), "django-html");
+        assert_eq!(detect("pages/promo.html"), "html");
+    }
+
     #[test]
     fn markers_outside_the_project_do_not_make_angular_templates() {
         let reg = reg();

crates/ide-lsp/Cargo.toml

@@ -29,4 +29,5 @@ zip.workspace = true
 
 [dev-dependencies]
 tempfile.workspace = true
+encoding_rs.workspace = true
 tokio = { workspace = true, features = ["rt-multi-thread", "macros", "test-util"] }

crates/ide-lsp/src/go_mod.rs

@@ -0,0 +1,223 @@
+//! go.mod as GoLand shows it: available upgrades, vulnerabilities and deprecated modules are
+//! reported as soon as the file is opened. gopls reports upgrades only from its "Check for
+//! upgrades" code lens, so that runs once per go.mod and session; its results (and the
+//! vulnerabilities from the `vulncheck` setting) come back as gopls diagnostics with quick fixes.
+//! gopls never reports a deprecated module, so `go list -m -u` does, on open and on save.
+
+use crate::LspManager;
+use crate::server::Server;
+use ide_core::{DocId, Pos, Range};
+use serde::Deserialize;
+use std::path::{Path, PathBuf};
+use std::sync::Arc;
+use std::time::Duration;
+
+pub(crate) const CHECK_UPGRADES: &str = "gopls.check_upgrades";
+/// gopls answers code lenses once it has loaded the module.
+const ATTEMPTS: u32 = 10;
+const RETRY: Duration = Duration::from_secs(2);
+/// Producer of the deprecation diagnostics (one full set per go.mod).
+const DEPRECATIONS: &str = "go-mod-deprecations";
+
+fn is_go_mod(path: &Path) -> bool {
+    path.file_name().is_some_and(|n| n == "go.mod")
+}
+
+impl LspManager {
+    pub(crate) async fn check_go_mod(&self, doc: DocId, path: &Path, server: Arc<Server>) {
+        if server.name != "gopls" || !is_go_mod(path) {
+            return;
+        }
+        self.report_deprecated_modules(doc, &server).await;
+        if !self.go_mod_checked.lock().insert(path.to_owned()) {
+            return;
+        }
+        for attempt in 0..ATTEMPTS {
+            if attempt > 0 {
+                tokio::time::sleep(RETRY).await;
+            }
+            if !self.docs.lock().contains_key(&doc) {
+                break;
+            }
+            let Ok(lenses) = self.code_lens(doc).await else { continue };
+            let Some(command) = lenses.into_iter().filter_map(|l| l.command).find(|c| c.command == CHECK_UPGRADES)
+            else {
+                continue;
+            };
+            if let Err(e) = self.execute_command(doc, command).await {
+                tracing::debug!("gopls: {CHECK_UPGRADES} for {}: {}", path.display(), e.message);
+            }
+            return;
+        }
+        // Not checked after all (closed, or gopls never offered the lens): a later open retries.
+        self.go_mod_checked.lock().remove(path);
+    }
+
+    /// After a save of a go.mod: its requirements may have changed.
+    pub(crate) fn go_mod_saved(&self, doc: DocId) {
+        let server = {
+            let docs = self.docs.lock();
+            let Some(d) = docs.get(&doc).filter(|d| is_go_mod(&d.path)) else { return };
+            let Some(a) = d.servers.iter().find(|a| a.server.name == "gopls") else { return };
+            a.server.clone()
+        };
+        let Some(me) = self.me.upgrade() else { return };
+        self.runtime.spawn(async move { me.report_deprecated_modules(doc, &server).await });
+    }
+
+    async fn report_deprecated_modules(&self, doc: DocId, server: &Server) {
+        let Some((path, text)) = self.docs.lock().get(&doc).map(|d| (d.path.clone(), d.text.as_str().to_owned()))
+        else {
+            return;
+        };
+        let required = required_modules(&text);
+        if required.is_empty() {
+            return;
+        }
+        let config = server.effective_config();
+        let search = crate::launch::server_search_path(&config);
+        let Some(dir) = path.parent().map(Path::to_path_buf) else { return };
+        let modules: Vec<String> = required.iter().map(|r| r.path.clone()).collect();
+        let listed = tokio::task::spawn_blocking(move || list_deprecations(&dir, &search, &modules)).await;
+        let Ok(Some(deprecated)) = listed else { return };
+        // The document changed meanwhile: its own save runs again.
+        if self.docs.lock().get(&doc).is_none_or(|d| d.text.as_str() != text) {
+            return;
+        }
+        let items = required
+            .into_iter()
+            .filter_map(|r| {
+                let message = deprecated.iter().find(|(p, _)| *p == r.path)?.1.trim();
+                Some(ide_core::Diagnostic {
+                    range: r.range,
+                    severity: ide_core::Severity::Warning,
+                    message: format!("{} is deprecated: {message}", r.path),
+                    source: Some("go".into()),
+                    code: None,
+                    unnecessary: false,
+                    deprecated: true,
+                    server: Some("gopls".into()),
+                })
+            })
+            .collect();
+        self.sink().emit(ide_core::IdeEvent::Diagnostics { path: path.into(), source: DEPRECATIONS.into(), items });
+    }
+}
+
+#[derive(Debug, PartialEq)]
+struct Required {
+    path: String,
+    /// The module path in go.mod (UTF-16 columns).
+    range: Range,
+}
+
+/// Modules of go.mod's `require` directives, single-line or in a block.
+fn required_modules(text: &str) -> Vec<Required> {
+    let mut out = Vec::new();
+    let mut in_block = false;
+    for (line, raw) in text.lines().enumerate() {
+        let code = raw.split("//").next().unwrap_or("");
+        let trimmed = code.trim_start();
+        let entry = if in_block {
+            if trimmed.starts_with(')') {
+                in_block = false;
+                continue;
+            }
+            trimmed
+        } else if let Some(rest) = trimmed.strip_prefix("require").filter(|r| r.starts_with(char::is_whitespace)) {
+            let rest = rest.trim_start();
+            if rest.starts_with('(') {
+                in_block = true;
+                continue;
+            }
+            rest
+        } else {
+            continue;
+        };
+        let mut words = entry.split_whitespace();
+        let (Some(module), Some(_version)) = (words.next(), words.next()) else { continue };
+        let module = module.trim_matches('"');
+        let Some(start) = code.find(module) else { continue };
+        let col = |byte: usize| code[..byte].encode_utf16().count() as u32;
+        let line = line as u32;
+        out.push(Required {
+            path: module.to_owned(),
+            range: Range { start: Pos { line, col: col(start) }, end: Pos { line, col: col(start + module.len()) } },
+        });
+    }
+    out
+}
+
+#[derive(Deserialize)]
+struct ListedModule {
+    #[serde(rename = "Path")]
+    path: String,
+    #[serde(rename = "Deprecated", default)]
+    deprecated: Option<String>,
+}
+
+/// `(module, message)` of each deprecated module in `modules`; `None` when `go` failed.
+fn list_deprecations(dir: &Path, search: &std::ffi::OsStr, modules: &[String]) -> Option<Vec<(String, String)>> {
+    let go: PathBuf = ide_core::tool_path::find_command("go", search, dir)?;
+    let output = ide_core::process::prepare(&mut std::process::Command::new(go))
+        .args(["list", "-m", "-u", "-e", "-json"])
+        .args(modules)
+        .current_dir(dir)
+        .env("PATH", search)
+        .stdin(std::process::Stdio::null())
+        .stderr(std::process::Stdio::null())
+        .output()
+        .ok()?;
+    if output.stdout.is_empty() {
+        tracing::debug!("go list -m -u in {}: {}", dir.display(), output.status);
+        return None;
+    }
+    Some(parse_deprecations(&output.stdout))
+}
+
+fn parse_deprecations(json: &[u8]) -> Vec<(String, String)> {
+    serde_json::Deserializer::from_slice(json)
+        .into_iter::<ListedModule>()
+        .map_while(Result::ok)
+        .filter_map(|m| Some((m.path, m.deprecated.filter(|d| !d.trim().is_empty())?)))
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn at(line: u32, from: u32, to: u32) -> Range {
+        Range { start: Pos { line, col: from }, end: Pos { line, col: to } }
+    }
+
+    #[test]
+    fn finds_required_modules_in_blocks_and_single_lines() {
+        let text = "module example.com/m\n\ngo 1.24\n\nrequire github.com/a/b v1.0.0 // indirect\n\
+                    require (\n\tgithub.com/c/d v1.2.0\n\t\"github.com/e/é\" v0.1.0 // indirect\n)\n\
+                    // require github.com/x/y v1.0.0\nreplace github.com/c/d => ../d\ntool golang.org/x/tools/cmd/stringer\n";
+        assert_eq!(
+            required_modules(text),
+            vec![
+                Required { path: "github.com/a/b".into(), range: at(4, 8, 22) },
+                Required { path: "github.com/c/d".into(), range: at(6, 1, 15) },
+                Required { path: "github.com/e/é".into(), range: at(7, 2, 16) },
+            ]
+        );
+    }
+
+    #[test]
+    fn reads_deprecations_from_the_go_list_stream() {
+        let json = br#"{"Path": "github.com/golang/protobuf", "Version": "v1.5.4",
+            "Deprecated": "Use the \"google.golang.org/protobuf\" module instead."}
+            {"Path": "github.com/sergi/go-diff", "Version": "v1.3.1"}
+            {"Path": "example.com/blank", "Deprecated": "  "}"#;
+        assert_eq!(
+            parse_deprecations(json),
+            vec![(
+                "github.com/golang/protobuf".to_owned(),
+                "Use the \"google.golang.org/protobuf\" module instead.".to_owned()
+            )]
+        );
+    }
+}

crates/ide-lsp/src/jdtls.rs

@@ -16,7 +16,7 @@ use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::time::{Duration, Instant};
 
-const SERVER: &str = "jdtls";
+pub(crate) const SERVER: &str = "jdtls";
 
 pub(crate) mod configuration;
 mod formatter;

crates/ide-lsp/src/launch.rs

@@ -146,7 +146,7 @@ fn required_env_set(config: &LanguageServerConfig) -> bool {
 }
 
 /// A configured `PATH` (e.g. a selected toolchain prepended) also resolves the binary.
-fn server_search_path(config: &LanguageServerConfig) -> OsString {
+pub(crate) fn server_search_path(config: &LanguageServerConfig) -> OsString {
     config.env.get("PATH").map(OsString::from).unwrap_or_else(search_path)
 }
 

crates/ide-lsp/src/lib.rs

@@ -15,6 +15,7 @@ mod convert;
 mod external_project;
 mod file_ops;
 mod file_watch;
+mod go_mod;
 mod go_scope;
 mod handler;
 mod injections;
@@ -221,6 +222,8 @@ pub struct LspManager {
     configuration_cache: Arc<Mutex<jdtls::configuration::ConfigurationCache>>,
     /// `window/showMessage` texts already surfaced; servers repeat them on every restart/reconfigure.
     shown_messages: Mutex<HashSet<(String, String)>>,
+    /// go.mod files whose upgrades gopls has been asked to check this session.
+    go_mod_checked: Mutex<HashSet<PathBuf>>,
     /// Virtual (non-`file:`) URIs a server returned, by the server that owns them.
     virtual_origins: Mutex<HashMap<String, ide_core::ServerId>>,
     /// Contents fetched for virtual URIs.
@@ -326,6 +329,41 @@ const RENAME_RETRY_DELAY: std::time::Duration = std::time::Duration::from_millis
 /// Implementation requests of one line-marker pass in flight at once.
 const IMPLEMENTATION_CONCURRENCY: usize = 4;
 
+/// How a virtual document's content was decoded, and whether it can be
+/// re-decoded ("Reload with Encoding").
+struct Decoding {
+    encoding: String,
+    has_bom: bool,
+    can_reload: bool,
+}
+
+impl Decoding {
+    /// Text the server decoded itself: no raw bytes here to re-read.
+    fn server_text() -> Self {
+        Decoding { encoding: "utf-8".into(), has_bom: false, can_reload: false }
+    }
+}
+
+/// jdtls' source attachment of a `jdt:` class (`java.project.resolveSourceAttachment`).
+struct SourceAttachment {
+    path: Option<String>,
+    encoding: Option<String>,
+    can_edit_encoding: bool,
+}
+
+/// Reads a `jar:` document's source: an entry as is, a class from the sources
+/// jar next to its binary. `encoding` decodes with it instead of detecting.
+fn read_jar_source(uri: &str, encoding: Option<&str>) -> Option<(String, ide_vfs::LoadedText)> {
+    match library_source::parse(uri) {
+        Some(e) if !e.entry.ends_with(".class") => {
+            library_source::read_entry(&e.jar, &e.entry, encoding).map(|loaded| (e.entry, loaded))
+        }
+        Some(_) => library_source::class_source(uri, encoding)
+            .and_then(|(source, loaded)| Some((library_source::parse(&source)?.entry, loaded))),
+        None => None,
+    }
+}
+
 /// Library classes in `jar:` targets (the official Kotlin LSP) go to their source
 /// in the artifact's sources jar when it is cached, at the declaration of the
 /// name navigated from; [`LspManager::virtual_document`] serves it.
@@ -340,8 +378,9 @@ async fn library_sources(snap: &DocSnap, pos: Pos, locs: Vec<Location>) -> Vec<L
                 let Some(uri) = loc.uri.as_deref().filter(|u| u.starts_with("jar:") && u.ends_with(".class")) else {
                     return loc;
                 };
-                let Some((source, text)) = library_source::class_source(uri) else { return loc };
-                let range = name.as_deref().map(|n| library_source::declaration_range(&text, n)).unwrap_or_default();
+                let Some((source, loaded)) = library_source::class_source(uri, None) else { return loc };
+                let range =
+                    name.as_deref().map(|n| library_source::declaration_range(&loaded.text, n)).unwrap_or_default();
                 Location { path: source.clone().into(), range, uri: Some(source) }
             })
             .collect()
@@ -433,6 +472,7 @@ impl LspManager {
             debug_servers: Mutex::new(HashMap::new()),
             configuration_cache: Arc::new(Mutex::new(Default::default())),
             shown_messages: Mutex::new(HashSet::new()),
+            go_mod_checked: Mutex::new(HashSet::new()),
             virtual_origins: Mutex::new(HashMap::new()),
             virtual_docs: Mutex::new(HashMap::new()),
             injections: injections::State::default(),
@@ -1032,6 +1072,7 @@ impl LspManager {
         servers: Vec<Arc<Server>>,
     ) {
         let canonical = dunce::canonicalize(&path).unwrap_or_else(|_| path.clone());
+        let canonical_path = canonical.clone();
         let compose_detected = language.as_str() == "yaml" && compose::is_content_detected_compose_file(&path, text);
         let mut state = DocState {
             path,
@@ -1062,6 +1103,13 @@ impl LspManager {
         self.schedule_pull(doc, None, Duration::ZERO);
         for s in &servers {
             self.ensure_started(s);
+            // Waits for a server still starting, so it is not tied to `running()` below.
+            if s.name == "gopls"
+                && let Some(me) = self.me.upgrade()
+            {
+                let (path, server) = (canonical_path.clone(), s.clone());
+                self.runtime.spawn(async move { me.check_go_mod(doc, &path, server).await });
+            }
             if s.running().is_some()
                 && let Some(me) = self.me.upgrade()
             {
@@ -1203,6 +1251,7 @@ impl LspManager {
         drop(docs);
         self.schedule_pull(doc, None, Duration::ZERO);
         self.pull_dependents(doc);
+        self.go_mod_saved(doc);
     }
 
     pub fn did_close(&self, doc: DocId) {
@@ -3020,8 +3069,9 @@ impl LspManager {
         let original = uri.to_owned();
         let archive = sources.clone();
         let found = tokio::task::spawn_blocking(move || {
-            library_source::source_in_archive(&original, &archive).map(|(uri, text)| {
-                let range = name.as_deref().map(|n| library_source::declaration_range(&text, n)).unwrap_or_default();
+            library_source::source_in_archive(&original, &archive, None).map(|(uri, loaded)| {
+                let range =
+                    name.as_deref().map(|n| library_source::declaration_range(&loaded.text, n)).unwrap_or_default();
                 Location { path: uri.clone().into(), uri: Some(uri), range }
             })
         })
@@ -3063,28 +3113,10 @@ impl LspManager {
         if scheme == "jar" {
             let found = {
                 let uri = uri.to_owned();
-                tokio::task::spawn_blocking(move || match library_source::parse(&uri) {
-                    Some(e) if !e.entry.ends_with(".class") => {
-                        library_source::read_entry(&e.jar, &e.entry).map(|text| (e.entry, text))
-                    }
-                    Some(_) => library_source::class_source(&uri)
-                        .and_then(|(source, text)| Some((library_source::parse(&source)?.entry, text))),
-                    None => None,
-                })
-                .await
-                .ok()
-                .flatten()
+                tokio::task::spawn_blocking(move || read_jar_source(&uri, None)).await.ok().flatten()
             };
-            if let Some((entry, text)) = found {
-                let title = entry.rsplit('/').next().unwrap_or(&entry).to_owned();
-                return Ok(self.store_virtual(
-                    uri,
-                    text,
-                    Some(title),
-                    None,
-                    &[],
-                    self.origin_server(uri).map(|s| s.id),
-                ));
+            if let Some((entry, loaded)) = found {
+                return Ok(self.store_jar_entry(uri, entry, loaded));
             }
         }
         let class_file = scheme == "jdt" || (scheme == "file" && uri.ends_with(".class"));
@@ -3155,7 +3187,21 @@ impl LspManager {
                     continue;
                 }
             };
-            return Ok(self.store_virtual(uri, text, None, description, &languages, Some(t.server.id)));
+            // jdtls decodes attached sources itself: its attachment encoding is
+            // the document's real charset, and editable ones can be re-decoded.
+            let decoding = if scheme == "jdt" && t.server.name == jdtls::SERVER && !virtual_doc::is_decompiled(&text) {
+                match self.jdt_source_attachment(uri).await {
+                    Some(att) if att.path.is_some() => Decoding {
+                        encoding: att.encoding.unwrap_or_else(|| "utf-8".into()),
+                        has_bom: false,
+                        can_reload: att.can_edit_encoding,
+                    },
+                    _ => Decoding::server_text(),
+                }
+            } else {
+                Decoding::server_text()
+            };
+            return Ok(self.store_virtual(uri, text, None, description, &languages, Some(t.server.id), decoding));
         }
         if jar_class && error.is_none() {
             return Err(IdeError::not_found(format!(
@@ -3167,6 +3213,7 @@ impl LspManager {
     }
 
     /// Caches `text` as the virtual document `uri`, titled `title` (else after the URI).
+    #[allow(clippy::too_many_arguments)]
     fn store_virtual(
         &self,
         uri: &str,
@@ -3175,6 +3222,7 @@ impl LspManager {
         description: Option<String>,
         languages: &[LanguageId],
         server: Option<ide_core::ServerId>,
+        decoding: Decoding,
     ) -> VirtualDocument {
         let decompiled = if virtual_doc::scheme(uri) == "csharp" {
             virtual_doc::is_csharp_decompiled(uri)
@@ -3195,6 +3243,9 @@ impl LspManager {
             title,
             description: description.or_else(|| virtual_doc::description(uri)),
             decompiled,
+            encoding: decoding.encoding,
+            has_bom: decoding.has_bom,
+            can_reload_encoding: decoding.can_reload,
         };
         if let Some(server) = server {
             self.virtual_origins.lock().entry(uri.to_owned()).or_insert(server);
@@ -3207,6 +3258,163 @@ impl LspManager {
         doc
     }
 
+    /// Caches a decoded `jar:` entry under the document's original URI, titled
+    /// after the entry; the backend owns these bytes, so they can be re-decoded.
+    fn store_jar_entry(&self, uri: &str, entry: String, loaded: ide_vfs::LoadedText) -> VirtualDocument {
+        let title = entry.rsplit('/').next().unwrap_or(&entry).to_owned();
+        self.store_virtual(
+            uri,
+            loaded.text,
+            Some(title),
+            None,
+            &[],
+            self.origin_server(uri).map(|s| s.id),
+            Decoding { encoding: loaded.encoding, has_bom: loaded.has_bom, can_reload: true },
+        )
+    }
+
+    /// The source attachment jdtls resolves for a `jdt:` class; `None` when the
+    /// command is unavailable or the class's container cannot be queried.
+    async fn jdt_source_attachment(&self, uri: &str) -> Option<SourceAttachment> {
+        let result = self
+            .jdtls_command(
+                &self.project_root,
+                "java.project.resolveSourceAttachment",
+                vec![json!({ "classFileUri": uri })],
+            )
+            .await
+            .ok()?;
+        if result.get("errorMessage").and_then(Value::as_str).is_some_and(|s| !s.is_empty()) {
+            return None;
+        }
+        let attrs = result.get("attributes")?;
+        let non_empty = |key: &str| attrs.get(key).and_then(Value::as_str).filter(|s| !s.is_empty()).map(str::to_owned);
+        Some(SourceAttachment {
+            path: non_empty("sourceAttachmentPath"),
+            encoding: non_empty("sourceAttachmentEncoding"),
+            can_edit_encoding: attrs.get("canEditEncoding").and_then(Value::as_bool).unwrap_or(true),
+        })
+    }
+
+    /// Updates a `jdt:` class's source attachment encoding. The command drops
+    /// the attachment when the path is omitted, so the resolved path is always
+    /// sent along with the encoding.
+    async fn update_jdt_source_encoding(&self, uri: &str, path: &str, encoding: &str) -> IdeResult<()> {
+        let result = self
+            .jdtls_command(
+                &self.project_root,
+                "java.project.updateSourceAttachment",
+                vec![json!({
+                    "classFileUri": uri,
+                    "attributes": { "sourceAttachmentPath": path, "sourceAttachmentEncoding": encoding },
+                })],
+            )
+            .await?;
+        if let Some(error) = result.get("errorMessage").and_then(Value::as_str).filter(|s| !s.is_empty()) {
+            return Err(IdeError::unavailable(error));
+        }
+        Ok(())
+    }
+
+    /// Waits until the resolved attachment reports `encoding`; `false` once
+    /// `until` passes. Maven applies attachment updates in a background job,
+    /// so the new encoding is not visible immediately after the update.
+    async fn wait_for_jdt_source_encoding(&self, uri: &str, encoding: &str, until: tokio::time::Instant) -> bool {
+        loop {
+            match self.jdt_source_attachment(uri).await {
+                Some(att) if att.encoding.as_deref() == Some(encoding) => return true,
+                _ if tokio::time::Instant::now() < until => {
+                    tokio::time::sleep(std::time::Duration::from_millis(150)).await;
+                }
+                _ => return false,
+            }
+        }
+    }
+
+    /// "Reload with Encoding" for a virtual document: re-reads its origin with
+    /// `encoding` and replaces the cached content. `jar:` entries are re-read
+    /// here; `jdt:` sources are decoded by jdtls, so its source attachment
+    /// encoding is updated and the contents fetched again (keeping the server's
+    /// text and positions in sync). Server-generated content cannot be re-decoded.
+    pub async fn reload_virtual(&self, uri: &str, encoding: &str) -> IdeResult<VirtualDocument> {
+        ide_vfs::encode("", encoding, false)?;
+        match virtual_doc::scheme(uri) {
+            "jar" => {
+                let (owned_uri, owned_encoding) = (uri.to_owned(), encoding.to_owned());
+                let found = tokio::task::spawn_blocking(move || read_jar_source(&owned_uri, Some(&owned_encoding)))
+                    .await
+                    .map_err(|e| IdeError::internal(e.to_string()))?;
+                let Some((entry, loaded)) = found else {
+                    return Err(IdeError::not_found(format!(
+                        "no source is available for {}",
+                        virtual_doc::title(uri, false)
+                    )));
+                };
+                Ok(self.store_jar_entry(uri, entry, loaded))
+            }
+            "jdt" if self.origin_server(uri).is_none_or(|s| s.name == jdtls::SERVER) => {
+                let Some(att) = self.jdt_source_attachment(uri).await else {
+                    return Err(IdeError::unavailable("jdtls cannot resolve the source attachment of this class"));
+                };
+                let Some(path) = att.path else {
+                    return Err(IdeError::invalid("this class has no attached sources to re-decode"));
+                };
+                if !att.can_edit_encoding {
+                    return Err(IdeError::invalid("the source attachment encoding of this library cannot be changed"));
+                }
+                self.update_jdt_source_encoding(uri, &path, encoding).await?;
+                // Maven containers apply the update in a background job (persist
+                // attached sources, then refresh the classpath): wait until the
+                // resolved attachment reports the new encoding, else the refetch
+                // below would still decode with the old one.
+                let deadline = tokio::time::Instant::now() + std::time::Duration::from_secs(10);
+                let first_try = tokio::time::Instant::now() + std::time::Duration::from_secs(3);
+                if !self.wait_for_jdt_source_encoding(uri, encoding, first_try).await {
+                    // jdtls matches the existing encoding attribute by reference
+                    // (`==`), so an entry restored from the saved container state
+                    // gains a duplicate attribute and keeps the old value. That
+                    // update still refreshes the container, after which a second
+                    // update replaces the value correctly.
+                    self.update_jdt_source_encoding(uri, &path, encoding).await?;
+                    if !self.wait_for_jdt_source_encoding(uri, encoding, deadline).await {
+                        return Err(IdeError::unavailable(
+                            "jdtls did not apply the source attachment encoding; try reloading again",
+                        ));
+                    }
+                }
+                // JDT keeps the class file's decoded buffer cached, so
+                // classFileContents would still return the old decoding: re-read
+                // the attached source entry here, like `jar:` documents. The
+                // server's open document is kept in sync by the regular
+                // document change flow.
+                let (owned_uri, owned_path, owned_encoding) = (uri.to_owned(), path.clone(), encoding.to_owned());
+                let found = tokio::task::spawn_blocking(move || {
+                    library_source::source_in_archive(&owned_uri, Path::new(&owned_path), Some(&owned_encoding))
+                })
+                .await
+                .map_err(|e| IdeError::internal(e.to_string()))?;
+                if let Some((_source_uri, loaded)) = found {
+                    return Ok(self.store_virtual(
+                        uri,
+                        loaded.text,
+                        None,
+                        None,
+                        &[],
+                        self.origin_server(uri).map(|s| s.id),
+                        Decoding { encoding: loaded.encoding, has_bom: loaded.has_bom, can_reload: true },
+                    ));
+                }
+                // Attachments that are not readable archives (e.g. folders):
+                // fall back to the server's contents.
+                self.virtual_docs.lock().remove(uri);
+                self.virtual_document(uri).await
+            }
+            _ => Err(IdeError::invalid(
+                "this document's content is generated by a language server and cannot be re-decoded with another encoding",
+            )),
+        }
+    }
+
     /// Called when a server sends `workspace/applyEdit`; installed by `src-tauri`
     /// so edits flow through `ide-workspace::Documents`.
     pub fn set_config_hook(&self, hook: Box<ConfigFn>) {

crates/ide-lsp/src/library_source.rs

@@ -7,8 +7,8 @@
 //! it in the Maven or Gradle cache.
 
 use ide_core::{Pos, Range};
+use ide_vfs::LoadedText;
 use percent_encoding::{AsciiSet, CONTROLS, percent_decode_str, utf8_percent_encode};
-use std::io::Read;
 use std::path::{Path, PathBuf};
 
 /// An entry of an archive named by a `jar:` URI.
@@ -57,29 +57,32 @@ impl JarEntry {
     }
 }
 
-/// The text of `entry` in the archive `jar`, when it is a UTF-8 file.
-pub(crate) fn read_entry(jar: &Path, entry: &str) -> Option<String> {
-    let mut zip = zip::ZipArchive::new(std::fs::File::open(jar).ok()?).ok()?;
-    let mut file = zip.by_name(entry).ok()?;
-    let mut text = String::new();
-    file.read_to_string(&mut text).ok()?;
-    Some(text)
+/// The text of `entry` in the archive `jar`, decoded like a file opened in the
+/// editor; `encoding` decodes with it instead of detecting ("Reload with
+/// Encoding"). `None` for binary or unreadable entries.
+pub(crate) fn read_entry(jar: &Path, entry: &str, encoding: Option<&str>) -> Option<LoadedText> {
+    let path = ide_vfs::archive_entry_path(jar, entry);
+    let loaded = match encoding {
+        Some(enc) => ide_vfs::load_text_as(&path, enc).ok()?,
+        None => ide_vfs::load_text(&path).ok()?,
+    };
+    (!loaded.binary).then_some(loaded)
 }
 
 /// The library source for a class entry: its `.kt` / `.java` file in the
 /// artifact's sources jar, as `(uri, text)`.
-pub(crate) fn class_source(uri: &str) -> Option<(String, String)> {
+pub(crate) fn class_source(uri: &str, encoding: Option<&str>) -> Option<(String, LoadedText)> {
     let jar = parse(uri)?;
     let class = jar.entry.strip_suffix(".class")?;
     for sources in sources_jars(&jar.jar) {
-        if let Some((entry, text)) = source_entry(&sources, class) {
+        if let Some((entry, text)) = source_entry(&sources, class, encoding) {
             return Some((jar.uri_of(&sources, &entry), text));
         }
     }
     None
 }
 
-pub(crate) fn source_in_archive(uri: &str, sources: &Path) -> Option<(String, String)> {
+pub(crate) fn source_in_archive(uri: &str, sources: &Path, encoding: Option<&str>) -> Option<(String, LoadedText)> {
     let jar = if uri.starts_with("jdt://contents/") {
         let path = uri.split('?').next()?.strip_prefix("jdt://contents/")?;
         let parts: Vec<_> = path.split('/').collect();
@@ -96,7 +99,7 @@ pub(crate) fn source_in_archive(uri: &str, sources: &Path) -> Option<(String, St
         parse(uri)?
     };
     let class = jar.entry.strip_suffix(".class")?;
-    let (entry, text) = source_entry(sources, class)?;
+    let (entry, text) = source_entry(sources, class, encoding)?;
     Some((jar.uri_of(sources, &entry), text))
 }
 
@@ -117,8 +120,8 @@ fn sources_jars(jar: &Path) -> Vec<PathBuf> {
 }
 
 /// The source file of `class` (`pkg/Name`, `pkg/Outer$Inner`, `pkg/FileKt`) in `sources`.
-fn source_entry(sources: &Path, class: &str) -> Option<(String, String)> {
-    let mut zip = zip::ZipArchive::new(std::fs::File::open(sources).ok()?).ok()?;
+fn source_entry(sources: &Path, class: &str, encoding: Option<&str>) -> Option<(String, LoadedText)> {
+    let zip = zip::ZipArchive::new(std::fs::File::open(sources).ok()?).ok()?;
     let (package, name) = class.rsplit_once('/').unwrap_or(("", class));
     let outer = name.split('$').next().unwrap_or(name);
     let dir = if package.is_empty() { String::new() } else { format!("{package}/") };
@@ -127,13 +130,9 @@ fn source_entry(sources: &Path, class: &str) -> Option<(String, String)> {
     if let Some(file) = outer.strip_suffix("Kt").filter(|f| !f.is_empty()) {
         candidates.push(format!("{dir}{file}.kt"));
     }
-    let read = |zip: &mut zip::ZipArchive<std::fs::File>, entry: &str| {
-        let mut text = String::new();
-        zip.by_name(entry).ok()?.read_to_string(&mut text).ok()?;
-        Some(text)
-    };
+    let read = |entry: &str| read_entry(sources, entry, encoding);
     for entry in &candidates {
-        if let Some(text) = read(&mut zip, entry) {
+        if let Some(text) = read(entry) {
             return Some((entry.clone(), text));
         }
     }
@@ -145,8 +144,8 @@ fn source_entry(sources: &Path, class: &str) -> Option<(String, String)> {
         .collect();
     let jvm_name = format!("@file:JvmName(\"{outer}\")");
     for entry in kotlin_files {
-        if let Some(text) = read(&mut zip, &entry)
-            && text.contains(&jvm_name)
+        if let Some(text) = read(&entry)
+            && text.text.contains(&jvm_name)
         {
             return Some((entry, text));
         }
@@ -233,11 +232,15 @@ mod tests {
     use std::io::Write;
 
     fn jar(path: &Path, entries: &[(&str, &str)]) {
+        jar_bytes(path, &entries.iter().map(|(n, t)| (*n, t.as_bytes())).collect::<Vec<_>>());
+    }
+
+    fn jar_bytes(path: &Path, entries: &[(&str, &[u8])]) {
         std::fs::create_dir_all(path.parent().unwrap()).unwrap();
         let mut zip = zip::ZipWriter::new(std::fs::File::create(path).unwrap());
-        for (name, text) in entries {
+        for (name, bytes) in entries {
             zip.start_file(*name, zip::write::SimpleFileOptions::default()).unwrap();
-            zip.write_all(text.as_bytes()).unwrap();
+            zip.write_all(bytes).unwrap();
         }
         zip.finish().unwrap();
     }
@@ -274,12 +277,12 @@ mod tests {
             "jdt://contents/lib-1.jar/p/Lib.java?=project/escaped-jar-path",
             "jar:file:///m2/g/lib/1/lib-1.jar!/p/Lib$Inner.class",
         ] {
-            let (uri, text) = source_in_archive(uri, &sources).unwrap();
+            let (uri, text) = source_in_archive(uri, &sources, None).unwrap();
             assert!(uri.ends_with("library%20sources.zip!/p/Lib.java"), "{uri}");
-            assert!(text.contains("class Lib"));
+            assert!(text.text.contains("class Lib"));
         }
-        assert!(source_in_archive("jdt://contents/lib.jar/p/Missing.class", &sources).is_none());
-        assert!(source_in_archive("csharp:/p/App.csproj/decompiled/Lib.cs", &sources).is_none());
+        assert!(source_in_archive("jdt://contents/lib.jar/p/Missing.class", &sources, None).is_none());
+        assert!(source_in_archive("csharp:/p/App.csproj/decompiled/Lib.cs", &sources, None).is_none());
     }
 
     #[test]
@@ -312,20 +315,103 @@ mod tests {
                 ("org/springframework/boot/Builder.class", "Builder.kt"),
                 ("Root.class", "Root.java"),
             ] {
-                let (source_uri, text) = class_source(&uri(class)).unwrap_or_else(|| panic!("{class} in {binary:?}"));
+                let (source_uri, text) =
+                    class_source(&uri(class), None).unwrap_or_else(|| panic!("{class} in {binary:?}"));
                 let dir = class.rsplit_once('/').map_or(String::new(), |(p, _)| format!("{p}/"));
                 assert!(source_uri.ends_with(&format!("-sources.jar!/{dir}{file}")), "{source_uri}");
                 assert_eq!(
-                    parse(&source_uri).and_then(|e| read_entry(&e.jar, &e.entry)).as_deref(),
-                    Some(text.as_str())
+                    parse(&source_uri).and_then(|e| read_entry(&e.jar, &e.entry, None)).map(|l| l.text),
+                    Some(text.text.clone())
                 );
             }
-            assert_eq!(class_source(&uri("org/springframework/boot/Missing.class")), None);
+            assert!(class_source(&uri("org/springframework/boot/Missing.class"), None).is_none());
         }
         // No sources jar: nothing to show from here.
         let lone = tmp.path().join("lone/x-1.jar");
         jar(&lone, &[]);
-        assert_eq!(class_source(&format!("jar://{}!/X.class", lone.to_string_lossy().replace('\\', "/"))), None);
+        assert!(class_source(&format!("jar://{}!/X.class", lone.to_string_lossy().replace('\\', "/")), None).is_none());
+    }
+
+    /// The reported case: a library source file saved as GBK bytes, not UTF-8.
+    const GBK_SAMPLE: &str = "package example.encoding;\n\n/** 中文编码测试。 */\npublic final class EncodingSample {\n    public static String message() {\n        return \"中文编码测试：是否启用\";\n    }\n}\n";
+
+    #[test]
+    fn archive_entries_decode_like_files_opened_in_the_editor() {
+        let tmp = tempfile::tempdir().unwrap();
+        let gbk = encoding_rs::GBK.encode(GBK_SAMPLE).0.into_owned();
+        // encoding_rs' encode() falls back to UTF-8 for UTF-16 (WHATWG has no encoder for it).
+        let mut utf16 = vec![0xFF, 0xFE];
+        utf16.extend(GBK_SAMPLE.encode_utf16().flat_map(u16::to_le_bytes));
+        let cases: Vec<(&str, Vec<u8>, &str, &str, bool)> = vec![
+            ("utf8.java", GBK_SAMPLE.as_bytes().to_vec(), GBK_SAMPLE, "utf-8", false),
+            ("bom.java", [b"\xEF\xBB\xBF", GBK_SAMPLE.as_bytes()].concat(), GBK_SAMPLE, "utf-8", true),
+            ("gbk.java", gbk, GBK_SAMPLE, "gbk", false),
+            ("utf16.java", utf16, GBK_SAMPLE, "utf-16le", true),
+        ];
+        for (name, bytes, text, encoding, has_bom) in cases {
+            let jar_path = tmp.path().join(format!("lib-{name}.jar"));
+            jar_bytes(&jar_path, &[(&format!("p/{name}"), &bytes)]);
+            let loaded = read_entry(&jar_path, &format!("p/{name}"), None).unwrap_or_else(|| panic!("{name}"));
+            assert_eq!(loaded.text, text, "{name}");
+            assert_eq!(loaded.encoding, encoding, "{name}");
+            assert_eq!(loaded.has_bom, has_bom, "{name}");
+            assert!(!loaded.binary, "{name}");
+        }
+        // Binary entries are not shown as text.
+        let jar_path = tmp.path().join("bin.jar");
+        jar_bytes(&jar_path, &[("p/img.png", &[0x89, b'P', b'N', b'G', 0, 0, 0, 0])]);
+        assert!(read_entry(&jar_path, "p/img.png", None).is_none());
+        assert!(read_entry(&jar_path, "p/missing.java", None).is_none());
+    }
+
+    #[test]
+    fn reload_decodes_archive_entries_with_the_chosen_encoding() {
+        let tmp = tempfile::tempdir().unwrap();
+        let jar_path = tmp.path().join("lib.jar");
+        let gbk = encoding_rs::GBK.encode(GBK_SAMPLE).0.into_owned();
+        jar_bytes(&jar_path, &[("p/EncodingSample.java", &gbk)]);
+        let loaded = read_entry(&jar_path, "p/EncodingSample.java", Some("gbk")).unwrap();
+        assert_eq!((loaded.text.as_str(), loaded.encoding.as_str()), (GBK_SAMPLE, "gbk"));
+        // An explicit encoding wins over detection, even when it decodes to replacement characters.
+        let forced = read_entry(&jar_path, "p/EncodingSample.java", Some("utf-8")).unwrap();
+        assert!(forced.text.contains('\u{FFFD}'));
+        assert_eq!(forced.encoding, "utf-8");
+        assert!(read_entry(&jar_path, "p/EncodingSample.java", Some("not-an-encoding")).is_none());
+    }
+
+    #[test]
+    fn class_sources_in_maven_caches_decode_non_utf8() {
+        let tmp = tempfile::tempdir().unwrap();
+        let m2 = tmp.path().join("m2/com/example/encoding-sample/1.0.0");
+        let gbk = encoding_rs::GBK.encode(GBK_SAMPLE).0.into_owned();
+        let facade = "@file:JvmName(\"SampleUtils\")\npackage example.encoding\n\n/** 中文注释。 */\nfun message() = \"中文编码测试：是否启用\"\n";
+        let facade_gbk = encoding_rs::GBK.encode(facade).0.into_owned();
+        jar(&m2.join("encoding-sample-1.0.0.jar"), &[]);
+        jar_bytes(
+            &m2.join("encoding-sample-1.0.0-sources.jar"),
+            &[("example/encoding/EncodingSample.java", &gbk), ("example/encoding/Renamed.kt", &facade_gbk)],
+        );
+        let uri = |class: &str| {
+            format!("jar://{}!/{class}", m2.join("encoding-sample-1.0.0.jar").to_string_lossy().replace('\\', "/"))
+        };
+        for (class, text) in
+            [("example/encoding/EncodingSample.class", GBK_SAMPLE), ("example/encoding/SampleUtils.class", facade)]
+        {
+            let (source_uri, loaded) = class_source(&uri(class), None).unwrap_or_else(|| panic!("{class}"));
+            assert!(
+                source_uri.ends_with("-sources.jar!/example/encoding/EncodingSample.java")
+                    || source_uri.ends_with("-sources.jar!/example/encoding/Renamed.kt")
+            );
+            assert_eq!(loaded.text, text, "{class}");
+            assert_eq!(loaded.encoding, "gbk", "{class}");
+            // The manually attached archive path decodes the same way.
+            let jdt = "jdt://contents/encoding-sample-1.0.0.jar/example.encoding/EncodingSample.class?=project/x";
+            let (_, attached) = source_in_archive(jdt, &m2.join("encoding-sample-1.0.0-sources.jar"), None).unwrap();
+            assert_eq!((attached.text.as_str(), attached.encoding.as_str()), (GBK_SAMPLE, "gbk"));
+        }
+        // Reload with an explicit encoding re-reads the same source.
+        let (_, reloaded) = class_source(&uri("example/encoding/EncodingSample.class"), Some("gbk")).unwrap();
+        assert_eq!((reloaded.text.as_str(), reloaded.encoding.as_str()), (GBK_SAMPLE, "gbk"));
     }
 
     #[test]

crates/ide-lsp/src/types.rs

@@ -357,6 +357,14 @@ pub struct VirtualDocument {
     pub description: Option<String>,
     /// Generated Java from a decompiler, rather than real source or a disassembler stub.
     pub decompiled: bool,
+    /// Charset the content was decoded with (a WHATWG label, e.g. `gbk`);
+    /// `utf-8` for text the server decoded itself.
+    pub encoding: String,
+    pub has_bom: bool,
+    /// "Reload with Encoding" can re-decode the origin's bytes (archive
+    /// entries, JDT sources with an editable attachment encoding); false for
+    /// server-generated content such as decompiled code.
+    pub can_reload_encoding: bool,
 }
 
 /// Reference updates for a file / folder move (`workspace/willRenameFiles`).

crates/ide-lsp/src/uri.rs

@@ -23,9 +23,20 @@ const PATH: &AsciiSet = &CONTROLS
     .add(b'}');
 
 pub fn path_to_uri_string(path: &Path) -> String {
-    let s = path.to_string_lossy();
-    let s = if cfg!(windows) { s.replace('\\', "/") } else { s.into_owned() };
+    let s = if cfg!(windows) {
+        dunce::simplified(path).to_string_lossy().replace('\\', "/")
+    } else {
+        path.to_string_lossy().into_owned()
+    };
     let mut out = String::from("file://");
+    // `\\server\share\p` → `file://server/share/p` (RFC 8089 Appendix E.3).
+    let unc = s.strip_prefix("//?/UNC/").or_else(|| s.strip_prefix("//")).filter(|_| cfg!(windows));
+    if let Some(unc) = unc {
+        let (host, rest) = unc.split_at(unc.find('/').unwrap_or(unc.len()));
+        out.extend(utf8_percent_encode(host, PATH));
+        out.extend(utf8_percent_encode(rest, PATH));
+        return out;
+    }
     if !s.starts_with('/') {
         out.push('/');
     }
@@ -41,21 +52,30 @@ pub fn path_to_uri(path: &Path) -> lsp_types::Uri {
     })
 }
 
-/// Converts a `file:` URI to a path; `None` for other schemes.
+/// Converts a `file:` URI to a path; `None` for other schemes. On Windows a
+/// host names a share (`file://server/share/p` → `\\server\share\p`) and the
+/// drive letter is upper-cased, as the rest of the IDE spells it.
 pub fn uri_to_path(uri: &str) -> Option<PathBuf> {
     let rest = uri.strip_prefix("file://").or_else(|| uri.strip_prefix("FILE://"))?;
-    // Skip an authority (`file://localhost/...`).
-    let path = match rest.find('/') {
-        Some(0) => rest,
-        Some(i) if rest[..i].eq_ignore_ascii_case("localhost") => &rest[i..],
-        _ => return None,
-    };
+    let (host, path) = rest.split_at(rest.find('/')?);
+    let local = host.is_empty() || host.eq_ignore_ascii_case("localhost");
     let path = path.split(['?', '#']).next().unwrap_or(path);
     let decoded = percent_decode_str(path).decode_utf8().ok()?;
     if cfg!(windows) {
+        if !local {
+            let host = percent_decode_str(host).decode_utf8().ok()?;
+            return Some(PathBuf::from(format!(r"\\{host}{}", decoded.replace('/', "\\"))));
+        }
         // `/C:/x` → `C:\x`
         let trimmed = decoded.strip_prefix('/').filter(|s| s.as_bytes().get(1) == Some(&b':')).unwrap_or(&decoded);
-        return Some(PathBuf::from(trimmed.replace('/', "\\")));
+        let mut path = trimmed.replace('/', "\\");
+        if path.as_bytes().get(1) == Some(&b':') {
+            path[..1].make_ascii_uppercase();
+        }
+        return Some(PathBuf::from(path));
+    }
+    if !local {
+        return None;
     }
     Some(PathBuf::from(decoded.into_owned()))
 }
@@ -89,6 +109,40 @@ mod tests {
         assert_eq!(uri_to_path("jdt://contents/x"), None);
     }
 
+    #[cfg(unix)]
+    #[test]
+    fn remote_hosts_are_not_local_paths() {
+        assert_eq!(uri_to_path("file://server/share/a.ts"), None);
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn windows_uris() {
+        for (uri, path) in [
+            ("file:///C:/a%20b/c.rs", r"C:\a b\c.rs"),
+            ("file:///c:/x/y.ts", r"C:\x\y.ts"),
+            ("file:///c%3A/x/y.ts", r"C:\x\y.ts"),
+            ("file:///C%3a/x", r"C:\x"),
+            ("file://localhost/d:/x", r"D:\x"),
+            ("file://server/share/a.ts", r"\\server\share\a.ts"),
+            ("file://server/share/a%20b/c.ts", r"\\server\share\a b\c.ts"),
+            ("file:////server/share/a.ts", r"\\server\share\a.ts"),
+        ] {
+            let got = uri_to_path(uri).unwrap();
+            assert_eq!(got.as_os_str(), path, "{uri}");
+        }
+        assert_eq!(uri_to_path("file://server"), None);
+        for (path, uri, back) in [
+            (r"C:\a b\c.rs", "file:///C:/a%20b/c.rs", r"C:\a b\c.rs"),
+            (r"\\?\C:\x\y.ts", "file:///C:/x/y.ts", r"C:\x\y.ts"),
+            (r"\\server\share\a b.ts", "file://server/share/a%20b.ts", r"\\server\share\a b.ts"),
+            (r"\\?\UNC\server\share\a.ts", "file://server/share/a.ts", r"\\server\share\a.ts"),
+        ] {
+            assert_eq!(path_to_uri(Path::new(path)).as_str(), uri, "{path}");
+            assert_eq!(uri_to_path(uri).unwrap().as_os_str(), back, "{path}");
+        }
+    }
+
     #[test]
     fn virtual_targets() {
         let jdt = "jdt://contents/rt.jar/java.lang/String.class?=p/%5C/x.jar%3Cjava.lang(String.class";

crates/ide-lsp/tests/mock_server.rs

@@ -306,6 +306,7 @@ fn harness_configured(
         indent: None,
         ui_mode: None,
         framework_ui_modes: Vec::new(),
+        framework_files: Vec::new(),
         formatter: None,
         scratch_template: None,
         tree_sitter: None,
@@ -3668,6 +3669,340 @@ async fn jdt_class_file_contents() {
     assert_eq!(source.title, "WithSources.java");
 }
 
+#[tokio::test(flavor = "multi_thread")]
+async fn jdt_library_sources_reload_with_the_attachment_encoding() {
+    let h = harness_for("java", "java", &[("jdtls", incremental_caps())], &[]);
+    h.open("App.java", "import example.encoding.EncodingSample;\n");
+    h.wait_status("jdtls", ServerStatus::Ready).await;
+    let s = h.launcher.state("jdtls");
+    let jdt = "jdt://contents/encoding-sample-1.0.jar/example.encoding/EncodingSample.class?=demo/%5C/m2%5C/encoding-sample-1.0.jar%3Cexample.encoding%28EncodingSample.class";
+
+    // The mock jdtls decodes the GBK attachment with the configured charset:
+    // until the encoding is updated, the text arrives garbled (U+FFFD).
+    let source = "package example.encoding;\n\n/** 中文编码测试。 */\npublic final class EncodingSample {}";
+    let garbled =
+        "package example.encoding;\n\n/** \u{FFFD}\u{FFFD}\u{FFFD}\u{FFFD} */\npublic final class EncodingSample {}";
+    let attachment_encoding: Arc<Mutex<Option<String>>> = Arc::default();
+    *s.responder.lock() = Some(Arc::new({
+        let encoding = attachment_encoding.clone();
+        move |_, method, params| match method {
+            "java/classFileContents" => {
+                let text = if encoding.lock().as_deref() == Some("gbk") { source } else { garbled };
+                Some(json!(text))
+            }
+            "workspace/executeCommand" => match params["command"].as_str()? {
+                "java.project.resolveSourceAttachment" => Some(json!({
+                    "errorMessage": null,
+                    "attributes": {
+                        "jarPath": "/m2/encoding-sample-1.0.jar",
+                        "sourceAttachmentPath": "/m2/encoding-sample-1.0-sources.jar",
+                        "sourceAttachmentEncoding": encoding.lock().clone(),
+                        "canEditEncoding": true,
+                    }
+                })),
+                "java.project.updateSourceAttachment" => {
+                    let attrs = &params["arguments"][0]["attributes"];
+                    *encoding.lock() = attrs["sourceAttachmentEncoding"].as_str().map(str::to_owned);
+                    Some(json!({ "errorMessage": null, "attributes": null }))
+                }
+                _ => None,
+            },
+            _ => None,
+        }
+    }));
+
+    let vd = h.mgr.virtual_document(jdt).await.unwrap();
+    assert_eq!(vd.text, garbled);
+    assert_eq!(vd.encoding, "utf-8", "no attachment encoding configured yet");
+    assert!(vd.can_reload_encoding);
+
+    let reloaded = h.mgr.reload_virtual(jdt, "gbk").await.unwrap();
+    assert_eq!(reloaded.text, source);
+    assert_eq!(reloaded.encoding, "gbk");
+    assert!(reloaded.can_reload_encoding);
+    // The update kept the attachment path (omitting it would drop the sources)
+    // and set the encoding; the contents were fetched again.
+    let updates: Vec<Value> = s
+        .requested("workspace/executeCommand")
+        .into_iter()
+        .filter(|p| p["command"] == "java.project.updateSourceAttachment")
+        .collect();
+    assert_eq!(updates.len(), 1);
+    assert_eq!(updates[0]["arguments"][0]["classFileUri"], jdt);
+    assert_eq!(updates[0]["arguments"][0]["attributes"]["sourceAttachmentPath"], "/m2/encoding-sample-1.0-sources.jar");
+    assert_eq!(updates[0]["arguments"][0]["attributes"]["sourceAttachmentEncoding"], "gbk");
+    assert!(s.requested("java/classFileContents").len() >= 2);
+    // The cache serves the re-decoded text without another round trip.
+    assert_eq!(h.mgr.virtual_document(jdt).await.unwrap().text, source);
+    // Round trip back to UTF-8.
+    let back = h.mgr.reload_virtual(jdt, "utf-8").await.unwrap();
+    assert_eq!(back.text, garbled);
+    assert_eq!(back.encoding, "utf-8");
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn jdt_reload_waits_for_the_maven_container_refresh() {
+    let h = harness_for("java", "java", &[("jdtls", incremental_caps())], &[]);
+    h.open("App.java", "class App {}\n");
+    h.wait_status("jdtls", ServerStatus::Ready).await;
+    let s = h.launcher.state("jdtls");
+    let jdt = "jdt://contents/lib.jar/p/Lib.class?=demo/%5C/m2%5C/lib.jar%3Cp%28Lib.class";
+    // m2e persists and refreshes the container in a background job: resolve
+    // keeps reporting the old encoding for a few calls after the update.
+    let state: Arc<Mutex<(Option<String>, usize)>> = Arc::default();
+    *s.responder.lock() = Some(Arc::new({
+        let state = state.clone();
+        move |_, method, params| match method {
+            "java/classFileContents" => {
+                let enc = state.lock().0.clone();
+                Some(json!(if enc.as_deref() == Some("gbk") {
+                    "package p; /** 中文 */ class Lib {}"
+                } else {
+                    "package p; /** \u{FFFD} */ class Lib {}"
+                }))
+            }
+            "workspace/executeCommand" => match params["command"].as_str()? {
+                "java.project.resolveSourceAttachment" => {
+                    let mut st = state.lock();
+                    st.1 += 1;
+                    let reported = if st.1 > 2 { st.0.clone() } else { None };
+                    Some(json!({
+                        "attributes": {
+                            "sourceAttachmentPath": "/m2/lib-sources.jar",
+                            "sourceAttachmentEncoding": reported,
+                            "canEditEncoding": true,
+                        }
+                    }))
+                }
+                "java.project.updateSourceAttachment" => {
+                    let mut st = state.lock();
+                    st.0 = params["arguments"][0]["attributes"]["sourceAttachmentEncoding"].as_str().map(str::to_owned);
+                    st.1 = 0;
+                    Some(json!({ "errorMessage": null }))
+                }
+                _ => None,
+            },
+            _ => None,
+        }
+    }));
+    let vd = h.mgr.virtual_document(jdt).await.unwrap();
+    assert!(vd.text.contains('\u{FFFD}'));
+    let reloaded = h.mgr.reload_virtual(jdt, "gbk").await.unwrap();
+    assert_eq!(reloaded.text, "package p; /** 中文 */ class Lib {}");
+    assert_eq!(reloaded.encoding, "gbk");
+    assert!(state.lock().1 >= 3, "polled until the container reported the new encoding");
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn jdt_reload_retries_when_a_restored_container_ignores_the_update() {
+    let h = harness_for("java", "java", &[("jdtls", incremental_caps())], &[]);
+    h.open("App.java", "class App {}\n");
+    h.wait_status("jdtls", ServerStatus::Ready).await;
+    let s = h.launcher.state("jdtls");
+    let jdt = "jdt://contents/lib.jar/p/Lib.class?=demo/%5C/m2%5C/lib.jar%3Cp%28Lib.class";
+    // jdtls replaces the encoding attribute by reference equality: an entry
+    // restored from the saved container state keeps the old value on the first
+    // update (a duplicate attribute is appended); only a second update, after
+    // the container was refreshed, applies the new one.
+    let state: Arc<Mutex<(Option<String>, usize)>> = Arc::default();
+    *s.responder.lock() = Some(Arc::new({
+        let state = state.clone();
+        move |_, method, params| match method {
+            "java/classFileContents" => {
+                let enc = state.lock().0.clone();
+                Some(json!(if enc.as_deref() == Some("gbk") {
+                    "package p; /** 中文 */ class Lib {}"
+                } else {
+                    "package p; /** \u{FFFD} */ class Lib {}"
+                }))
+            }
+            "workspace/executeCommand" => match params["command"].as_str()? {
+                "java.project.resolveSourceAttachment" => Some(json!({
+                    "attributes": {
+                        "sourceAttachmentPath": "/m2/lib-sources.jar",
+                        "sourceAttachmentEncoding": state.lock().0.clone(),
+                        "canEditEncoding": true,
+                    }
+                })),
+                "java.project.updateSourceAttachment" => {
+                    let mut st = state.lock();
+                    st.1 += 1;
+                    if st.1 > 1 {
+                        st.0 = params["arguments"][0]["attributes"]["sourceAttachmentEncoding"]
+                            .as_str()
+                            .map(str::to_owned);
+                    }
+                    Some(json!({ "errorMessage": null }))
+                }
+                _ => None,
+            },
+            _ => None,
+        }
+    }));
+    let vd = h.mgr.virtual_document(jdt).await.unwrap();
+    assert!(vd.text.contains('\u{FFFD}'));
+    let reloaded = h.mgr.reload_virtual(jdt, "gbk").await.unwrap();
+    assert_eq!(reloaded.text, "package p; /** 中文 */ class Lib {}");
+    assert_eq!(reloaded.encoding, "gbk");
+    let updates: Vec<Value> = s
+        .requested("workspace/executeCommand")
+        .into_iter()
+        .filter(|p| p["command"] == "java.project.updateSourceAttachment")
+        .collect();
+    assert_eq!(updates.len(), 2, "the ignored first update was retried once");
+    assert!(updates.iter().all(|u| u["arguments"][0]["attributes"]["sourceAttachmentPath"] == "/m2/lib-sources.jar"));
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn jdt_reload_reads_the_attachment_when_the_server_buffer_is_stale() {
+    use std::io::Write;
+    let tmp = tempfile::tempdir().unwrap();
+    let sources = tmp.path().join("lib-sources.jar");
+    let source = "package p; /** 中文 */ class Lib {}";
+    let gbk = encoding_rs::GBK.encode(source).0.into_owned();
+    let mut zip = zip::ZipWriter::new(std::fs::File::create(&sources).unwrap());
+    zip.start_file("p/Lib.java", zip::write::SimpleFileOptions::default()).unwrap();
+    zip.write_all(&gbk).unwrap();
+    zip.finish().unwrap();
+
+    let h = harness_for("java", "java", &[("jdtls", incremental_caps())], &[]);
+    h.open("App.java", "class App {}\n");
+    h.wait_status("jdtls", ServerStatus::Ready).await;
+    let s = h.launcher.state("jdtls");
+    let jdt = "jdt://contents/lib.jar/p/Lib.class?=demo/%5C/m2%5C/lib.jar%3Cp%28Lib.class";
+    // JDT caches the decoded buffer of a class file: even after the attachment
+    // encoding is updated, classFileContents keeps returning the old decoding.
+    let encoding: Arc<Mutex<Option<String>>> = Arc::default();
+    *s.responder.lock() = Some(Arc::new({
+        let encoding = encoding.clone();
+        let sources = sources.clone();
+        move |_, method, params| match method {
+            "java/classFileContents" => Some(json!("package p; /** \u{FFFD} */ class Lib {}")),
+            "workspace/executeCommand" => match params["command"].as_str()? {
+                "java.project.resolveSourceAttachment" => Some(json!({
+                    "attributes": {
+                        "sourceAttachmentPath": sources.to_string_lossy(),
+                        "sourceAttachmentEncoding": encoding.lock().clone(),
+                        "canEditEncoding": true,
+                    }
+                })),
+                "java.project.updateSourceAttachment" => {
+                    *encoding.lock() =
+                        params["arguments"][0]["attributes"]["sourceAttachmentEncoding"].as_str().map(str::to_owned);
+                    Some(json!({ "errorMessage": null }))
+                }
+                _ => None,
+            },
+            _ => None,
+        }
+    }));
+    let vd = h.mgr.virtual_document(jdt).await.unwrap();
+    assert!(vd.text.contains('\u{FFFD}'));
+    let reloaded = h.mgr.reload_virtual(jdt, "gbk").await.unwrap();
+    assert_eq!(reloaded.text, source, "read from the attachment, not the stale server buffer");
+    assert_eq!(reloaded.encoding, "gbk");
+    assert!(reloaded.can_reload_encoding);
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn jdt_reload_is_refused_when_the_sources_cannot_be_re_decoded() {
+    let h = harness_for("java", "java", &[("jdtls", incremental_caps())], &[]);
+    h.open("App.java", "class App {}\n");
+    h.wait_status("jdtls", ServerStatus::Ready).await;
+    let s = h.launcher.state("jdtls");
+    let class =
+        |name: &str| format!("jdt://contents/lib.jar/p/{name}.class?=demo/%5C/m2%5C/lib.jar%3Cp%28{name}.class");
+    s.respond("java/classFileContents", json!("package p;\npublic class Lib {}"));
+
+    // A container that does not allow editing the attachment encoding.
+    *s.responder.lock() = Some(Arc::new(|_, method, params| match method {
+        "workspace/executeCommand" if params["command"] == "java.project.resolveSourceAttachment" => Some(json!({
+            "attributes": { "sourceAttachmentPath": "/m2/lib-sources.jar", "canEditEncoding": false }
+        })),
+        _ => None,
+    }));
+    let vd = h.mgr.virtual_document(&class("ReadOnly")).await.unwrap();
+    assert!(!vd.can_reload_encoding);
+    let err = h.mgr.reload_virtual(&class("ReadOnly"), "gbk").await.unwrap_err();
+    assert!(err.message.contains("cannot be changed"), "{err}");
+
+    // Decompiled content has no attached sources to re-decode.
+    *s.responder.lock() = Some(Arc::new(|_, method, params| match method {
+        "workspace/executeCommand" if params["command"] == "java.project.resolveSourceAttachment" => Some(json!({
+            "attributes": { "sourceAttachmentPath": null, "canEditEncoding": true }
+        })),
+        _ => None,
+    }));
+    s.respond(
+        "java/classFileContents",
+        json!("// Source code is decompiled from a .class file using FernFlower decompiler (from Intellij IDEA).\npackage p;\npublic class Lib {}"),
+    );
+    let decompiled = h.mgr.virtual_document(&class("Decompiled")).await.unwrap();
+    assert!(decompiled.decompiled && !decompiled.can_reload_encoding);
+    let err = h.mgr.reload_virtual(&class("Decompiled"), "gbk").await.unwrap_err();
+    assert!(err.message.contains("no attached sources"), "{err}");
+
+    // The resolve command fails (unqueryable container): no reload offered.
+    s.errors.lock().insert("workspace/executeCommand".into(), (-32603, "unsupported".into()));
+    let unresolved = h.mgr.virtual_document(&class("Unresolved")).await.unwrap();
+    assert_eq!(unresolved.encoding, "utf-8");
+    assert!(!unresolved.can_reload_encoding);
+    let err = h.mgr.reload_virtual(&class("Unresolved"), "gbk").await.unwrap_err();
+    assert!(err.message.contains("cannot resolve"), "{err}");
+
+    // Server-generated content of other schemes cannot be re-decoded at all.
+    let err = h.mgr.reload_virtual("csharp:/p/App.csproj/decompiled/Lib.cs", "gbk").await.unwrap_err();
+    assert!(err.message.contains("generated by a language server"), "{err}");
+    // Unknown encodings are refused before any server round trip.
+    assert!(h.mgr.reload_virtual(&class("ReadOnly"), "not-an-encoding").await.is_err());
+}
+
+#[tokio::test(flavor = "multi_thread")]
+async fn jar_library_sources_reload_with_another_encoding() {
+    use std::io::Write;
+    let repo = tempfile::tempdir().unwrap();
+    let dir = repo.path().join("com/example/encoding-sample/1.0.0");
+    std::fs::create_dir_all(&dir).unwrap();
+    let source = "package example.encoding\n\n/** 中文编码测试。 */\nfun message() = \"中文编码测试：是否启用\"\n";
+    let gbk = encoding_rs::GBK.encode(source).0.into_owned();
+    let jar_bytes = |path: &Path, entries: &[(&str, &[u8])]| {
+        let mut zip = zip::ZipWriter::new(std::fs::File::create(path).unwrap());
+        for (name, bytes) in entries {
+            zip.start_file(*name, zip::write::SimpleFileOptions::default()).unwrap();
+            zip.write_all(bytes).unwrap();
+        }
+        zip.finish().unwrap();
+    };
+    jar_bytes(&dir.join("encoding-sample-1.0.jar"), &[("example/encoding/EncodingSampleKt.class", b"\0")]);
+    jar_bytes(&dir.join("encoding-sample-1.0-sources.jar"), &[("example/encoding/EncodingSample.kt", &gbk)]);
+    let jar_uri = |jar: &Path, entry: &str| format!("jar://{}!/{entry}", uri_of(jar).trim_start_matches("file://"));
+
+    let h = harness_for("kotlin", "kt", &[("kotlin-lsp", incremental_caps())], &[]);
+    h.open("Main.kt", "fun main() {}\n");
+    h.wait_status("kotlin-lsp", ServerStatus::Ready).await;
+    let class = jar_uri(&dir.join("encoding-sample-1.0.jar"), "example/encoding/EncodingSampleKt.class");
+    let entry = jar_uri(&dir.join("encoding-sample-1.0-sources.jar"), "example/encoding/EncodingSample.kt");
+
+    let vd = h.mgr.virtual_document(&class).await.unwrap();
+    assert_eq!(vd.text, source);
+    assert_eq!(vd.encoding, "gbk");
+    assert!(vd.can_reload_encoding);
+    // An explicit encoding wins over detection, even when it garbles the text.
+    let forced = h.mgr.reload_virtual(&class, "utf-8").await.unwrap();
+    assert!(forced.text.contains('\u{FFFD}'));
+    assert_eq!(forced.encoding, "utf-8");
+    let back = h.mgr.reload_virtual(&class, "gbk").await.unwrap();
+    assert_eq!((back.text.as_str(), back.encoding.as_str()), (source, "gbk"));
+    // Non-class entries reload the same way.
+    let entry_vd = h.mgr.virtual_document(&entry).await.unwrap();
+    assert_eq!((entry_vd.text.as_str(), entry_vd.encoding.as_str()), (source, "gbk"));
+    let entry_reload = h.mgr.reload_virtual(&entry, "gbk").await.unwrap();
+    assert_eq!(entry_reload.text, source);
+    // Missing sources fail cleanly.
+    let missing = jar_uri(&dir.join("encoding-sample-1.0.jar"), "example/encoding/Missing.class");
+    assert!(h.mgr.reload_virtual(&missing, "gbk").await.is_err());
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn class_file_opening_routes_sources_and_binary_documents() {
     let mut caps = incremental_caps();

crates/ide-lsp/tests/real_servers.rs

@@ -55,6 +55,7 @@ fn lang(id: &str, ext: &str, server: LanguageServerConfig) -> LanguageConfig {
         indent: None,
         ui_mode: None,
         framework_ui_modes: Vec::new(),
+        framework_files: Vec::new(),
         formatter: None,
         scratch_template: None,
         tree_sitter: None,

crates/ide-remote/src/deploy.rs

@@ -69,7 +69,7 @@ pub struct TransferError {
 }
 
 impl TransferReport {
-    fn fail(&mut self, path: impl Into<String>, e: IdeError) {
+    pub(crate) fn fail(&mut self, path: impl Into<String>, e: IdeError) {
         self.errors.push(TransferError { path: path.into(), message: e.message });
     }
 }

crates/ide-remote/src/service.rs

@@ -286,6 +286,70 @@ impl RemoteService {
         r
     }
 
+    /// Remote Host › Download to…: `remotes` (folders recursively) into the local folder `dir`,
+    /// each under its own name, without the server path above it. Existing files are replaced.
+    pub async fn download_into(
+        &self,
+        connection: &FsConnection,
+        remotes: &[String],
+        dir: &Path,
+        cancel: &CancellationToken,
+        progress: &mut (dyn FnMut(&str, usize, usize) + Send),
+    ) -> IdeResult<TransferReport> {
+        let fs = self.fs(connection).await?;
+        let mut report = TransferReport::default();
+        let mut folders = Vec::new();
+        let mut jobs = Vec::new();
+        for remote in remotes {
+            let Some(top) = download_target(dir, remote, remote) else {
+                report.skipped += 1;
+                continue;
+            };
+            match fs.stat(remote).await {
+                Ok(Some(e)) if e.is_dir => {
+                    folders.push(top);
+                    let mut entries = Vec::new();
+                    if let Err(e) = remote_tree(&fs, remote, cancel, &mut entries).await {
+                        report.fail(remote.clone(), e);
+                    }
+                    for entry in entries {
+                        match download_target(dir, remote, &entry.path) {
+                            Some(local) if entry.is_dir => folders.push(local),
+                            Some(local) => jobs.push((entry.path, local)),
+                            None => report.skipped += 1,
+                        }
+                    }
+                }
+                Ok(Some(_)) => jobs.push((remote.clone(), top)),
+                Ok(None) => report.fail(remote.clone(), IdeError::not_found(format!("{remote} does not exist"))),
+                Err(e) => report.fail(remote.clone(), e),
+            }
+        }
+        for folder in &folders {
+            if let Err(e) = tokio::fs::create_dir_all(folder).await {
+                report.fail(folder.display().to_string(), e.into());
+            }
+        }
+        for (i, (remote, local)) in jobs.iter().enumerate() {
+            if cancel.is_cancelled() {
+                break;
+            }
+            progress(remote, i, jobs.len());
+            if let Some(parent) = local.parent()
+                && let Err(e) = tokio::fs::create_dir_all(parent).await
+            {
+                report.fail(remote.clone(), e.into());
+                continue;
+            }
+            match fs.download(remote, local).await {
+                Ok(()) => report.files += 1,
+                Err(e) => report.fail(remote.clone(), e),
+            }
+        }
+        fs.close().await;
+        Ok(report)
+    }
+
     // --- save hook -----------------------------------------------------------------
 
     /// After a document save: uploads a remote file's copy, or (automatic upload)
@@ -497,3 +561,70 @@ fn cache_key(connection: &FsConnection) -> String {
         FsConnection::Sftp { ssh } => format!("sftp-{ssh}"),
     }
 }
+
+/// Files and folders under remote folder `dir` (symlinked folders are not followed).
+async fn remote_tree(
+    fs: &RemoteFs,
+    dir: &str,
+    cancel: &CancellationToken,
+    out: &mut Vec<RemoteEntry>,
+) -> IdeResult<()> {
+    for e in fs.list(dir).await? {
+        if cancel.is_cancelled() {
+            return Err(IdeError::cancelled());
+        }
+        let descend = e.is_dir && !e.is_symlink;
+        let path = e.path.clone();
+        out.push(e);
+        if descend {
+            Box::pin(remote_tree(fs, &path, cancel, out)).await?;
+        }
+    }
+    Ok(())
+}
+
+/// Where remote `path`, inside the downloaded `selected` file or folder, lands under local `dir`:
+/// `dir/<name of selected>/<rest>`. `None` for a name that would leave `dir`.
+fn download_target(dir: &Path, selected: &str, path: &str) -> Option<PathBuf> {
+    let selected = selected.trim_end_matches('/');
+    let name = selected.rsplit('/').next()?;
+    let rest = path.trim_end_matches('/').strip_prefix(selected)?;
+    if !rest.is_empty() && !rest.starts_with('/') {
+        return None;
+    }
+    let mut local = dir.to_path_buf();
+    for part in std::iter::once(name).chain(rest.split('/').filter(|p| !p.is_empty())) {
+        if matches!(part, "" | "." | "..") || part.contains('\\') || (cfg!(windows) && part.contains(':')) {
+            return None;
+        }
+        local.push(part);
+    }
+    Some(local)
+}
+
+#[cfg(test)]
+mod download_into_tests {
+    use super::*;
+
+    #[test]
+    fn downloads_keep_only_the_selected_name() {
+        let dir = Path::new("/p/project");
+        let selected = "/home/u/www/site/current/drush";
+        assert_eq!(download_target(dir, selected, selected), Some(dir.join("drush")));
+        assert_eq!(download_target(dir, "/home/u/www/site/current/drush/", selected), Some(dir.join("drush")));
+        assert_eq!(
+            download_target(dir, selected, "/home/u/www/site/current/drush/src/a.php"),
+            Some(dir.join("drush").join("src").join("a.php"))
+        );
+        assert_eq!(download_target(dir, "/srv/app.log", "/srv/app.log"), Some(dir.join("app.log")));
+    }
+
+    #[test]
+    fn names_that_would_leave_the_folder_are_refused() {
+        let dir = Path::new("/p/project");
+        assert_eq!(download_target(dir, "/srv/a", "/srv/a/../../etc/passwd"), None);
+        assert_eq!(download_target(dir, "/srv/a", "/srv/ab/x"), None, "a sibling with the same prefix");
+        assert_eq!(download_target(dir, "/", "/etc"), None, "the root has no name");
+        assert_eq!(download_target(dir, "/srv/..", "/srv/.."), None);
+    }
+}

crates/ide-remote/tests/local.rs

@@ -319,3 +319,37 @@ async fn browser_mappings_resolve_symlinks_and_download_to_the_project() {
     assert!(report.errors.is_empty());
     assert_eq!(std::fs::read_to_string(local).unwrap(), "from the server");
 }
+
+#[tokio::test]
+async fn download_into_copies_only_the_selected_items() {
+    let tmp = tempfile::tempdir().unwrap();
+    let server = tmp.path().join("srv/www/site/current");
+    let project = tmp.path().join("project");
+    std::fs::create_dir_all(server.join("drush/sub")).unwrap();
+    std::fs::create_dir_all(server.join("drush/empty")).unwrap();
+    std::fs::create_dir_all(&project).unwrap();
+    std::fs::write(server.join("drush/a.txt"), "a").unwrap();
+    std::fs::write(server.join("drush/sub/b.txt"), "b").unwrap();
+    std::fs::write(server.join("index.php"), "php").unwrap();
+    std::fs::write(project.join("index.php"), "old").unwrap();
+    let service = service(tmp.path());
+    let remotes = [server.join("drush"), server.join("index.php")].map(|p| p.to_str().unwrap().to_owned());
+    let report = service
+        .download_into(&FsConnection::Local, &remotes, &project, &CancellationToken::new(), &mut |_, _, _| {})
+        .await
+        .unwrap();
+    assert_eq!(report.files, 3, "{report:?}");
+    assert!(report.errors.is_empty(), "{report:?}");
+    assert_eq!(std::fs::read_to_string(project.join("drush/a.txt")).unwrap(), "a");
+    assert_eq!(std::fs::read_to_string(project.join("drush/sub/b.txt")).unwrap(), "b");
+    assert!(project.join("drush/empty").is_dir());
+    assert_eq!(std::fs::read_to_string(project.join("index.php")).unwrap(), "php");
+    assert!(!project.join("srv").exists() && !project.join("www").exists());
+
+    let missing = [server.join("gone").to_str().unwrap().to_owned()];
+    let report = service
+        .download_into(&FsConnection::Local, &missing, &project, &CancellationToken::new(), &mut |_, _, _| {})
+        .await
+        .unwrap();
+    assert_eq!((report.files, report.errors.len()), (0, 1), "{report:?}");
+}

crates/ide-sdk/src/java.rs

@@ -1541,7 +1541,7 @@ pub fn usages_bundle(data_dir: &Path) -> Option<PathBuf> {
     install_bundle(
         data_dir,
         "java-usages",
-        "1.12.0",
+        "1.13.0",
         include_bytes!("../../../java/java-usages/openidea-java-usages.jar"),
     )
 }

crates/ide-vcs/src/status.rs

@@ -5,6 +5,7 @@ use crate::{ChangeKind, FileStatus, Repo};
 use gix::status::index_worktree::Item as WtItem;
 use gix::status::plumbing::index_as_worktree::{Change as WtChange, EntryStatus};
 use ide_core::IdeResult;
+use ide_core::ignored::IgnoredNames;
 use std::collections::{BTreeMap, HashSet};
 
 #[derive(Default)]
@@ -15,10 +16,43 @@ struct Entry {
 }
 
 pub(crate) fn status(r: &Repo) -> IdeResult<Vec<FileStatus>> {
+    let ignored = r.ignored.read().unwrap_or_else(|p| p.into_inner()).clone();
+    // gitoxide stops at the first IO error (a directory it may not read), where git warns
+    // and lists the rest: git answers then.
+    let (map, conflicts) = gix_status(r, &ignored).or_else(|e| {
+        tracing::debug!("status via gitoxide failed, asking git: {}", e.message);
+        cli_status(r, &ignored)
+    })?;
+    Ok(map
+        .into_iter()
+        .filter(|(_, e)| e.staged.is_some() || e.unstaged.is_some())
+        // Ignored names mean "the IDE treats these as nonexistent": hide their tracked
+        // changes too, not just untracked hits above. Conflicts stay visible so merges
+        // cannot stall on a file the user cannot see.
+        .filter(|(rel, _)| conflicts.contains(rel) || !ignored.is_ignored_path(rel))
+        .map(|(rel, mut e)| {
+            if conflicts.contains(&rel) {
+                e.staged = None;
+                e.renamed_from = None;
+                e.unstaged = Some(ChangeKind::Conflicted);
+            }
+            FileStatus {
+                path: r.abs_path(&rel).into(),
+                rel_path: rel,
+                staged: e.staged,
+                unstaged: e.unstaged,
+                renamed_from: e.renamed_from,
+            }
+        })
+        .collect())
+}
+
+type Entries = (BTreeMap<String, Entry>, HashSet<String>);
+
+fn gix_status(r: &Repo, ignored: &IgnoredNames) -> IdeResult<Entries> {
     let repo = r.gix()?;
     let mut map: BTreeMap<String, Entry> = BTreeMap::new();
     let mut conflicts: HashSet<String> = HashSet::new();
-    let ignored = r.ignored.read().unwrap_or_else(|p| p.into_inner()).clone();
 
     // Stamp before status can read the index: stamping after the load could capture
     // an external `git switch`, `add` or commit's new index and allow the stale
@@ -118,28 +152,60 @@ pub(crate) fn status(r: &Repo) -> IdeResult<Vec<FileStatus>> {
         }
     }
 
-    Ok(map
-        .into_iter()
-        .filter(|(_, e)| e.staged.is_some() || e.unstaged.is_some())
-        // Ignored names mean "the IDE treats these as nonexistent": hide their tracked
-        // changes too, not just untracked hits above. Conflicts stay visible so merges
-        // cannot stall on a file the user cannot see.
-        .filter(|(rel, _)| conflicts.contains(rel) || !ignored.is_ignored_path(rel))
-        .map(|(rel, mut e)| {
-            if conflicts.contains(&rel) {
-                e.staged = None;
-                e.renamed_from = None;
-                e.unstaged = Some(ChangeKind::Conflicted);
+    Ok((map, conflicts))
+}
+
+/// `git status --porcelain=v2`: what git lists, unreadable directories skipped.
+fn cli_status(r: &Repo, ignored: &IgnoredNames) -> IdeResult<Entries> {
+    let out = crate::cli::run(r.root(), &["status", "--porcelain=v2", "-z", "--untracked-files=all"], None)?;
+    Ok(parse_porcelain_v2(&String::from_utf8_lossy(&out.stdout), ignored))
+}
+
+fn parse_porcelain_v2(out: &str, ignored: &IgnoredNames) -> Entries {
+    let kind = |c: u8| match c {
+        b'M' | b'T' => Some(ChangeKind::Modified),
+        b'A' | b'C' => Some(ChangeKind::Added),
+        b'D' => Some(ChangeKind::Deleted),
+        b'R' => Some(ChangeKind::Renamed),
+        _ => None,
+    };
+    let mut map: BTreeMap<String, Entry> = BTreeMap::new();
+    let mut conflicts: HashSet<String> = HashSet::new();
+    let mut records = out.split('\0');
+    while let Some(record) = records.next() {
+        let (tag, rest) = record.split_once(' ').unwrap_or((record, ""));
+        match tag {
+            // `1 XY sub mH mI mW hH hI path`, `2 … Xscore path` + NUL + the original path.
+            "1" | "2" => {
+                let fields = if tag == "1" { 8 } else { 9 };
+                let mut parts = rest.splitn(fields, ' ');
+                let xy = parts.next().unwrap_or("..").as_bytes();
+                let Some(path) = parts.nth(fields - 2) else { continue };
+                let e = map.entry(path.to_owned()).or_default();
+                e.staged = xy.first().copied().and_then(kind);
+                // Intent to add shows as `.A`; worktree renames are off, as with gitoxide.
+                e.unstaged = xy.get(1).copied().and_then(kind).filter(|k| *k != ChangeKind::Renamed);
+                if tag == "2" {
+                    let from = records.next().unwrap_or_default();
+                    if e.staged == Some(ChangeKind::Renamed) {
+                        e.renamed_from = Some(from.to_owned());
+                    }
+                }
             }
-            FileStatus {
-                path: r.abs_path(&rel).into(),
-                rel_path: rel,
-                staged: e.staged,
-                unstaged: e.unstaged,
-                renamed_from: e.renamed_from,
+            // `u XY sub m1 m2 m3 mW h1 h2 h3 path`
+            "u" => {
+                if let Some(path) = rest.splitn(10, ' ').nth(9) {
+                    conflicts.insert(path.to_owned());
+                    map.entry(path.to_owned()).or_default().unstaged = Some(ChangeKind::Conflicted);
+                }
             }
-        })
-        .collect())
+            "?" if !rest.is_empty() && !ignored.is_ignored_path(rest) => {
+                map.entry(rest.to_owned()).or_default().unstaged = Some(ChangeKind::Untracked);
+            }
+            _ => {}
+        }
+    }
+    (map, conflicts)
 }
 
 /// Lets a test land an external index write in the window between the status run
@@ -227,4 +293,59 @@ mod tests {
         let staged = Command::new("git").current_dir(dir).args(["diff", "--cached", "--stat"]).output().unwrap();
         assert!(staged.stdout.is_empty(), "{}", String::from_utf8_lossy(&staged.stdout));
     }
+
+    /// git's porcelain answer (used when gitoxide can't read the tree) matches gitoxide's.
+    #[test]
+    fn git_and_gitoxide_report_the_same_status() {
+        let tmp = tempfile::tempdir().unwrap();
+        let dir = tmp.path();
+        git(dir, &["init", "-q"]);
+        git(dir, &["config", "user.name", "Test User"]);
+        git(dir, &["config", "user.email", "[email protected]"]);
+        git(dir, &["config", "commit.gpgsign", "false"]);
+        for f in ["modified.txt", "staged.txt", "deleted.txt", "staged_del.txt", "both.txt", "conflict.txt"] {
+            std::fs::write(dir.join(f), "a\n").unwrap();
+        }
+        std::fs::write(dir.join("rename_me.txt"), "some longer content\nthat is stable\nfor rename detection\n")
+            .unwrap();
+        commit_all(dir, "base");
+        git(dir, &["checkout", "-q", "-b", "side"]);
+        std::fs::write(dir.join("conflict.txt"), "side\n").unwrap();
+        commit_all(dir, "side");
+        git(dir, &["checkout", "-q", "main"]);
+        std::fs::write(dir.join("conflict.txt"), "main\n").unwrap();
+        commit_all(dir, "main");
+        let merge = Command::new("git").current_dir(dir).args(["merge", "-q", "side"]).output().unwrap();
+        assert!(!merge.status.success());
+
+        std::fs::write(dir.join("modified.txt"), "b\n").unwrap();
+        std::fs::write(dir.join("staged.txt"), "b\n").unwrap();
+        git(dir, &["add", "staged.txt"]);
+        std::fs::remove_file(dir.join("deleted.txt")).unwrap();
+        git(dir, &["rm", "-q", "staged_del.txt"]);
+        std::fs::write(dir.join("both.txt"), "b\n").unwrap();
+        git(dir, &["add", "both.txt"]);
+        std::fs::write(dir.join("both.txt"), "c\n").unwrap();
+        git(dir, &["mv", "rename_me.txt", "renamed with space.txt"]);
+        std::fs::create_dir_all(dir.join("new dir")).unwrap();
+        std::fs::write(dir.join("new dir/untracked.txt"), "u\n").unwrap();
+        std::fs::write(dir.join("intent.txt"), "i\n").unwrap();
+        git(dir, &["add", "-N", "intent.txt"]);
+
+        let repo = Repo::discover(dir).unwrap().expect("repository found");
+        let ignored = IgnoredNames::default();
+        let show = |(map, conflicts): Entries| {
+            let mut c: Vec<_> = conflicts.into_iter().collect();
+            c.sort();
+            let m: Vec<_> = map
+                .into_iter()
+                .map(|(k, e)| format!("{k}: {:?} {:?} {:?}", e.staged, e.unstaged, e.renamed_from))
+                .collect();
+            (m, c)
+        };
+        let from_git = show(cli_status(&repo, &ignored).unwrap());
+        assert_eq!(from_git, show(gix_status(&repo, &ignored).unwrap()));
+        assert!(from_git.0.iter().any(|l| l.starts_with("renamed with space.txt: Some(Renamed)")), "{from_git:?}");
+        assert_eq!(from_git.1, ["conflict.txt"]);
+    }
 }

crates/ide-vcs/tests/repo.rs

@@ -2015,3 +2015,24 @@ fn reword_refuses_commits_outside_the_current_branch() {
     fx.git(&["checkout", "-q", "main"]);
     assert!(fx.repo().reword(&side, "other").is_err());
 }
+
+#[cfg(unix)]
+#[test]
+fn status_skips_a_directory_it_cannot_read() {
+    // `git status` warns "could not open directory: Permission denied" and lists the rest.
+    use std::os::unix::fs::PermissionsExt;
+    let fx = Fixture::new();
+    fx.write("a.txt", "a\n");
+    fx.commit_all("init");
+    fx.write("a.txt", "b\n");
+    fx.write("new.txt", "n\n");
+    let locked = fx.path("locked");
+    std::fs::create_dir(&locked).unwrap();
+    std::fs::write(locked.join("inside.txt"), "x").unwrap();
+    std::fs::set_permissions(&locked, std::fs::Permissions::from_mode(0o000)).unwrap();
+    let st = fx.repo().status();
+    std::fs::set_permissions(&locked, std::fs::Permissions::from_mode(0o755)).unwrap();
+    let st = st.unwrap();
+    assert_eq!(status_of(&st, "a.txt").unstaged, Some(ChangeKind::Modified));
+    assert_eq!(status_of(&st, "new.txt").unstaged, Some(ChangeKind::Untracked));
+}

crates/ide-vfs/src/encoding.rs

@@ -359,6 +359,32 @@ fn sync_error_is_tolerable(e: &std::io::Error) -> bool {
     false
 }
 
+/// On Windows a file can't be replaced while another process has it open without
+/// delete sharing: an antivirus or indexer scan, a sync client, a program reading
+/// its config. Those let go within moments, so the replacing rename is retried briefly.
+const RENAME_ATTEMPTS: u32 = 10;
+const RENAME_PAUSE: std::time::Duration = std::time::Duration::from_millis(100);
+
+/// Access denied (os error 5), sharing and lock violations (32, 33) on Windows.
+fn held_by_another_process(e: &std::io::Error) -> bool {
+    cfg!(windows) && matches!(e.raw_os_error(), Some(5 | 32 | 33))
+}
+
+fn retrying(
+    attempts: u32,
+    pause: std::time::Duration,
+    transient: impl Fn(&std::io::Error) -> bool,
+    mut op: impl FnMut() -> std::io::Result<()>,
+) -> std::io::Result<()> {
+    for _ in 1..attempts {
+        match op() {
+            Err(e) if transient(&e) => std::thread::sleep(pause),
+            r => return r,
+        }
+    }
+    op()
+}
+
 /// Writes `bytes` to `path` atomically: temp file in the same directory, fsync,
 /// rename over the target. Preserves the permissions of an existing file and
 /// writes through symlinks. Falls back to an in-place write when the directory
@@ -441,7 +467,7 @@ fn write_atomic_impl(path: &Path, bytes: &[u8], allow_in_place: bool, private: b
             fs::set_permissions(&tmp, permissions)?;
         }
         drop(file);
-        fs::rename(&tmp, &target)
+        retrying(RENAME_ATTEMPTS, RENAME_PAUSE, held_by_another_process, || fs::rename(&tmp, &target))
     })();
     if let Err(e) = result {
         let _ = fs::remove_file(&tmp);
@@ -539,6 +565,58 @@ mod tests {
         assert_eq!(fs::metadata(&target).unwrap().permissions().mode() & 0o777, 0o640);
     }
 
+    #[test]
+    fn replacing_is_retried_only_while_a_file_is_held() {
+        use std::io::{Error, ErrorKind};
+        let in_use = || Error::from_raw_os_error(32);
+        let transient = |e: &Error| e.raw_os_error() == Some(32);
+        let zero = std::time::Duration::ZERO;
+        for (fails, outcome) in [(0, true), (3, true), (RENAME_ATTEMPTS - 1, true), (RENAME_ATTEMPTS, false)] {
+            let mut calls = 0;
+            let r = retrying(RENAME_ATTEMPTS, zero, transient, || {
+                calls += 1;
+                if calls <= fails { Err(in_use()) } else { Ok(()) }
+            });
+            assert_eq!(r.is_ok(), outcome, "{fails} failures");
+            assert_eq!(calls, (fails + 1).min(RENAME_ATTEMPTS));
+        }
+        let mut calls = 0;
+        let r = retrying(RENAME_ATTEMPTS, zero, transient, || {
+            calls += 1;
+            Err(Error::from(ErrorKind::NotFound))
+        });
+        assert_eq!(r.unwrap_err().kind(), ErrorKind::NotFound);
+        assert_eq!(calls, 1, "other errors fail at once");
+
+        for code in [5, 32, 33] {
+            assert_eq!(held_by_another_process(&Error::from_raw_os_error(code)), cfg!(windows), "os error {code}");
+        }
+        assert!(!held_by_another_process(&Error::from(ErrorKind::NotFound)));
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn saving_waits_for_a_windows_file_lock_to_be_released() {
+        use std::os::windows::fs::OpenOptionsExt;
+        use windows_sys::Win32::Storage::FileSystem::{FILE_SHARE_READ, FILE_SHARE_WRITE};
+        // No sharing at all (os error 32), and readers that don't allow deletion (os error 5).
+        for share in [0, FILE_SHARE_READ | FILE_SHARE_WRITE] {
+            let dir = tempfile::tempdir().unwrap();
+            let path = dir.path().join("config.json");
+            fs::write(&path, b"old").unwrap();
+            let held = fs::OpenOptions::new().read(true).share_mode(share).open(&path).unwrap();
+            let release = std::thread::spawn(move || {
+                std::thread::sleep(std::time::Duration::from_millis(300));
+                drop(held);
+            });
+            let result = write_atomic(&path, b"new");
+            release.join().unwrap();
+            result.unwrap();
+            assert_eq!(fs::read(&path).unwrap(), b"new", "share mode {share}");
+            assert_eq!(fs::read_dir(dir.path()).unwrap().count(), 1, "no temp file left behind");
+        }
+    }
+
     #[cfg(unix)]
     #[test]
     fn strict_write_does_not_truncate_when_sibling_creation_is_denied() {

crates/ide-workspace/src/documents.rs

@@ -25,6 +25,11 @@ pub struct DocumentInfo {
     pub line_ending: LineEnding,
     pub read_only: bool,
     pub dirty: bool,
+    /// Whether "Reload with Encoding" can re-decode this document's source
+    /// bytes: true for files and virtual documents the backend can re-read
+    /// (archive entries, JDT sources with an editable attachment encoding,
+    /// Git revisions); false for server-generated content (decompiled code).
+    pub can_reload_encoding: bool,
     /// Larger than `ide_vfs::LARGE_FILE_THRESHOLD`: language servers, syntax
     /// structure and folding are disabled; the editor should drop heavy features.
     #[specta(optional)]
@@ -143,6 +148,9 @@ struct DocState {
     observed: bool,
     binary: bool,
     dirty: bool,
+    can_reload_encoding: bool,
+    /// The user picked `encoding`; reloads keep it instead of detecting again.
+    encoding_chosen: bool,
     /// Disk state we last loaded or wrote; changes matching it are our own.
     disk_mtime: f64,
     disk_len: u64,
@@ -339,6 +347,7 @@ impl Documents {
             line_ending: st.doc.line_ending(),
             read_only: st.read_only,
             dirty: st.dirty,
+            can_reload_encoding: st.can_reload_encoding,
             large: st.large,
             editorconfig: st.editorconfig.clone(),
             uri: st.uri.clone(),
@@ -412,6 +421,8 @@ impl Documents {
             observed,
             binary: loaded.binary,
             dirty: false,
+            can_reload_encoding: true,
+            encoding_chosen: false,
             disk_mtime: loaded.mtime_ms,
             disk_len: disk_len(path),
             closed: false,
@@ -449,8 +460,19 @@ impl Documents {
 
     /// Opens (or re-references) a read-only virtual document: contents a
     /// language server provides for a non-`file:` URI. It is keyed by the URI,
-    /// never touches the disk and cannot be edited or saved.
-    pub fn open_virtual(&self, uri: &str, language: LanguageId, text: &str) -> IdeResult<DocumentInfo> {
+    /// never touches the disk and cannot be edited or saved. `encoding` /
+    /// `has_bom` describe how the content was decoded (not a guess);
+    /// `can_reload_encoding` tells whether [`Documents::replace_virtual`] can
+    /// re-decode it ("Reload with Encoding").
+    pub fn open_virtual(
+        &self,
+        uri: &str,
+        language: LanguageId,
+        text: &str,
+        encoding: &str,
+        has_bom: bool,
+        can_reload_encoding: bool,
+    ) -> IdeResult<DocumentInfo> {
         let _operation = self.operations.lock();
         let key = PathBuf::from(uri);
         if let Some(info) = self.reopen(&key) {
@@ -462,8 +484,8 @@ impl Documents {
             doc: Document::new(text),
             language,
             ui_mode: None,
-            encoding: "utf-8".into(),
-            has_bom: false,
+            encoding: encoding.into(),
+            has_bom,
             native_to_ascii: false,
             read_only: true,
             large,
@@ -471,6 +493,8 @@ impl Documents {
             observed: true,
             binary: false,
             dirty: false,
+            can_reload_encoding,
+            encoding_chosen: false,
             disk_mtime: 0.0,
             disk_len: 0,
             closed: false,
@@ -846,6 +870,7 @@ impl Documents {
                 let loaded = Self::load_as(&st.path, encoding, enabled)?;
                 st.native_to_ascii = enabled;
                 st.encoding = loaded.encoding.clone();
+                st.encoding_chosen = true;
                 st.has_bom = loaded.has_bom;
                 st.disk_mtime = loaded.mtime_ms;
                 st.disk_len = disk_len(&st.path);
@@ -864,12 +889,45 @@ impl Documents {
                 ide_vfs::encode(&st.doc.text_for_save(), encoding, has_bom)?;
             }
             st.encoding = encoding.to_owned();
+            st.encoding_chosen = true;
             st.has_bom = has_bom;
             self.set_dirty(doc, st, true);
             Ok(DocumentEncoding { encoding: st.encoding.clone(), has_bom: st.has_bom })
         })
     }
 
+    /// The URI of a virtual document, or `None` for a file-backed one.
+    pub fn virtual_uri(&self, doc: DocId) -> IdeResult<Option<String>> {
+        self.with_doc(doc, |st| Ok(st.uri.clone()))
+    }
+
+    /// Re-decoded content of a virtual document ("Reload with Encoding"):
+    /// replaces the text and the encoding label, keeping the document
+    /// read-only and clean. The caller re-reads the origin (archive entry,
+    /// language server, Git blob) with the chosen encoding first.
+    pub fn replace_virtual(
+        &self,
+        doc: DocId,
+        text: &str,
+        encoding: &str,
+        has_bom: bool,
+    ) -> IdeResult<DocumentEncoding> {
+        self.with_doc(doc, |st| {
+            if st.uri.is_none() {
+                return Err(IdeError::invalid("not a virtual document"));
+            }
+            ide_vfs::encode("", encoding, false)?;
+            st.doc.set_line_ending(LineEnding::detect(text));
+            self.replace_locked(doc, st, text)?;
+            st.encoding = encoding.to_owned();
+            st.has_bom = has_bom;
+            st.large = text.len() as u64 > ide_vfs::LARGE_FILE_THRESHOLD;
+            // Reloading is not an edit: the buffer matches its source again.
+            self.set_dirty(doc, st, false);
+            Ok(DocumentEncoding { encoding: st.encoding.clone(), has_bom: st.has_bom })
+        })
+    }
+
     /// Adds or removes the BOM on a UTF-8 document; the change is written on save.
     pub fn set_bom(&self, doc: DocId, has_bom: bool) -> IdeResult<DocumentEncoding> {
         self.with_doc(doc, |st| {
@@ -968,8 +1026,13 @@ impl Documents {
                     Self::load_as(&st.path, &st.encoding, st.native_to_ascii)?
                 } else {
                     let defaults = self.file_defaults();
-                    let loaded = Self::load_with_defaults(&st.path, &defaults)?;
-                    st.native_to_ascii = defaults.native_to_ascii_for(&st.path);
+                    let native_to_ascii = defaults.native_to_ascii_for(&st.path);
+                    let loaded = if st.encoding_chosen {
+                        Self::load_as(&st.path, &st.encoding, native_to_ascii)?
+                    } else {
+                        Self::load_with_defaults(&st.path, &defaults)?
+                    };
+                    st.native_to_ascii = native_to_ascii;
                     loaded
                 };
                 st.disk_mtime = loaded.mtime_ms;

crates/ide-workspace/src/documents/workspace_edit.rs

@@ -748,6 +748,7 @@ impl Documents {
             let result = self.with_doc(*id, |state| {
                 self.replace_locked(*id, state, &before.doc.text())?;
                 state.encoding = before.encoding.clone();
+                state.encoding_chosen = before.encoding_chosen;
                 state.has_bom = before.has_bom;
                 state.doc.set_line_ending(before.doc.line_ending());
                 state.disk_mtime = fs::metadata(&state.path).map(|m| ide_vfs::mtime_ms(&m)).unwrap_or(0.0);
@@ -789,7 +790,11 @@ impl Documents {
                     return Err(stale(path));
                 }
                 let defaults = self.file_defaults();
-                let loaded = ide_vfs::load_text_with_fallback(path, defaults.fallback_for(path))?;
+                let loaded = if state.encoding_chosen {
+                    Self::load_as(path, &state.encoding, state.native_to_ascii)?
+                } else {
+                    ide_vfs::load_text_with_fallback(path, defaults.fallback_for(path))?
+                };
                 self.replace_locked(id, state, &loaded.text)?;
                 state.encoding = loaded.encoding;
                 state.has_bom = loaded.has_bom;

crates/ide-workspace/tests/documents.rs

@@ -505,6 +505,48 @@ fn reload_and_convert_encoding() {
     assert!(f.docs.set_encoding(info.id, "gbk", true).is_err());
 }
 
+#[test]
+fn external_changes_keep_a_chosen_encoding() {
+    // Valid UTF-8 bytes, so detection alone would read them as UTF-8.
+    let (first, changed) = (b"caf\xC3\xA9".as_slice(), b"caf\xC3\xA9 \xC3\xA8".as_slice());
+    for (encoding, reload) in [("windows-1252", true), ("gbk", true), ("windows-1252", false)] {
+        let f = fixture();
+        let path = f.root.join("legacy.txt");
+        fs::write(&path, first).unwrap();
+        let info = f.docs.open(&path).unwrap();
+        assert_eq!(info.encoding, "utf-8");
+        if reload {
+            f.docs.set_encoding(info.id, encoding, true).unwrap();
+        } else {
+            // Convert, then save: the file is now in the chosen encoding.
+            f.docs.replace_all(info.id, "café").unwrap();
+            f.docs.set_encoding(info.id, encoding, false).unwrap();
+            f.docs.save(info.id).unwrap();
+        }
+        let expected =
+            |bytes: &[u8]| encoding_rs::Encoding::for_label(encoding.as_bytes()).unwrap().decode(bytes).0.into_owned();
+        let changed = if reload { changed.to_vec() } else { ide_vfs::encode("café è", encoding, false).unwrap() };
+        fs::write(&path, &changed).unwrap();
+        f.docs.on_disk_changed(std::slice::from_ref(&path));
+        let snapshot = f.docs.snapshot(info.id).unwrap();
+        assert_eq!(snapshot.text, expected(&changed), "{encoding} reload={reload}");
+        assert_eq!(snapshot.encoding, encoding, "{encoding} reload={reload}");
+        assert!(!snapshot.dirty);
+    }
+}
+
+#[test]
+fn external_changes_redetect_an_encoding_the_user_never_chose() {
+    let f = fixture();
+    let path = f.root.join("plain.txt");
+    fs::write(&path, "plain").unwrap();
+    let info = f.docs.open(&path).unwrap();
+    fs::write(&path, ide_vfs::encode("wide", "utf-16le", true).unwrap()).unwrap();
+    f.docs.on_disk_changed(std::slice::from_ref(&path));
+    let snapshot = f.docs.snapshot(info.id).unwrap();
+    assert_eq!((snapshot.text.as_str(), snapshot.encoding.as_str()), ("wide", "utf-16le"));
+}
+
 #[test]
 fn utf8_bom_is_added_and_removed_on_save() {
     let f = fixture();
@@ -656,14 +698,14 @@ fn editorconfig_applies_on_open_and_save() {
 fn virtual_documents_are_read_only_and_keyed_by_uri() {
     let f = fixture();
     let uri = "jdt://contents/a.jar/p/C.class?=x";
-    let info = f.docs.open_virtual(uri, LanguageId::new("java"), "class C {}\n").unwrap();
+    let info = f.docs.open_virtual(uri, LanguageId::new("java"), "class C {}\n", "utf-8", false, true).unwrap();
     assert_eq!(info.uri.as_deref(), Some(uri));
     assert_eq!(info.path, PathBuf::from(uri));
     assert!(info.read_only && !info.dirty);
     assert_eq!(info.language.as_str(), "java");
 
     // Re-opening shares the document; edits and saves never reach a file.
-    let again = f.docs.open_virtual(uri, LanguageId::new("java"), "ignored").unwrap();
+    let again = f.docs.open_virtual(uri, LanguageId::new("java"), "ignored", "utf-8", false, true).unwrap();
     assert_eq!(again.id, info.id);
     assert_eq!(again.text, "class C {}\n");
     let err = f.docs.edit(info.id, info.version, change(0, 0, "x")).unwrap_err();
@@ -677,6 +719,68 @@ fn virtual_documents_are_read_only_and_keyed_by_uri() {
     assert_eq!(*f.rec.log.lock(), vec!["open v0 java".to_owned(), "close".to_owned()]);
 }
 
+#[test]
+fn virtual_documents_carry_their_encoding_and_reload_capability() {
+    let f = fixture();
+    // Archive sources decoded by the backend report the charset actually used.
+    let uri = "jar:///m2/lib-1.0-sources.jar!/p/C.java";
+    let info = f.docs.open_virtual(uri, LanguageId::new("java"), "中文", "gbk", false, true).unwrap();
+    assert_eq!((info.encoding.as_str(), info.has_bom, info.can_reload_encoding), ("gbk", false, true));
+    let bom =
+        f.docs.open_virtual("jar:///m2/b.jar!/p/B.java", LanguageId::new("java"), "x", "utf-8", true, true).unwrap();
+    assert!(bom.has_bom);
+    // Server-generated content (decompiled) cannot be re-decoded.
+    let decompiled = f
+        .docs
+        .open_virtual(
+            "csharp:/p/App.csproj/decompiled/Lib.cs",
+            LanguageId::new("csharp"),
+            "class Lib {}",
+            "utf-8",
+            false,
+            false,
+        )
+        .unwrap();
+    assert!(!decompiled.can_reload_encoding);
+    // File-backed documents can always be re-read from disk.
+    let path = f.root.join("f.txt");
+    fs::write(&path, "x").unwrap();
+    assert!(f.docs.open(&path).unwrap().can_reload_encoding);
+}
+
+#[test]
+fn virtual_documents_reload_with_another_encoding_without_becoming_editable() {
+    let f = fixture();
+    let uri = "jdt://contents/a.jar/p/C.class?=x";
+    let info = f.docs.open_virtual(uri, LanguageId::new("java"), "涓枃", "utf-8", false, true).unwrap();
+    let encoding = f.docs.replace_virtual(info.id, "中文", "gbk", false).unwrap();
+    assert_eq!((encoding.encoding.as_str(), encoding.has_bom), ("gbk", false));
+    let snap = f.docs.snapshot(info.id).unwrap();
+    assert_eq!(snap.text, "中文");
+    assert_eq!(snap.encoding, "gbk");
+    assert!(snap.read_only && !snap.dirty, "reloading is not an edit");
+    assert!(snap.version > info.version);
+    assert_eq!(f.docs.virtual_uri(info.id).unwrap().as_deref(), Some(uri));
+    // The replacement reached observers and the event stream (editors resync).
+    assert!(f.rec.log.lock().iter().any(|l| l.starts_with("change v") && l.contains("中文")));
+    assert!(f.events.lock().iter().any(|e| matches!(e, IdeEvent::DocPatched { doc, .. } if *doc == info.id)));
+
+    // Read-only protection is unchanged.
+    assert_eq!(f.docs.edit(info.id, snap.version, change(0, 0, "x")).unwrap_err().kind, ErrorKind::PermissionDenied);
+    assert!(f.docs.set_encoding(info.id, "utf-8", false).is_err());
+    assert!(f.docs.set_encoding(info.id, "gbk", true).is_err(), "the op layer routes virtual reloads");
+    assert!(f.docs.set_bom(info.id, true).is_err());
+    f.docs.save(info.id).unwrap();
+
+    // Unknown encodings are refused; file-backed documents are not virtual.
+    assert!(f.docs.replace_virtual(info.id, "x", "not-an-encoding", false).is_err());
+    let path = f.root.join("f.txt");
+    fs::write(&path, "x").unwrap();
+    let file = f.docs.open(&path).unwrap();
+    assert!(f.docs.replace_virtual(file.id, "y", "utf-8", false).is_err());
+    assert_eq!(f.docs.virtual_uri(file.id).unwrap(), None);
+}
+
 #[test]
 fn toggling_the_writable_bit_updates_the_open_document() {
     let f = fixture();

crates/ide-workspace/tests/workspace_edits.rs

@@ -162,6 +162,21 @@ fn undo_id(events: &Mutex<Vec<IdeEvent>>) -> u32 {
         .expect("successful transaction has one undo record")
 }
 
+#[test]
+fn undo_keeps_the_encoding_chosen_for_a_file_opened_after_the_edit() {
+    let tmp = tempfile::tempdir().unwrap();
+    let path = tmp.path().join("legacy.txt");
+    std::fs::write(&path, b"abc\xC3\xA9").unwrap();
+    let (docs, events) = recorded_documents();
+    docs.apply_workspace_edit(&WorkspaceEdit { files: vec![edit(&path, "new")], ..Default::default() }).unwrap();
+    let info = docs.open(&path).unwrap();
+    docs.set_encoding(info.id, "windows-1252", true).unwrap();
+    assert_eq!(docs.snapshot(info.id).unwrap().text, "newé");
+    docs.undo_workspace_edit(undo_id(&events)).unwrap();
+    let snapshot = docs.snapshot(info.id).unwrap();
+    assert_eq!((snapshot.text.as_str(), snapshot.encoding.as_str()), ("abcé", "windows-1252"));
+}
+
 #[test]
 fn stale_document_version_rejects_the_whole_edit() {
     let tmp = tempfile::tempdir().unwrap();
@@ -515,6 +530,18 @@ fn duplicate_edits_keep_versions_and_apply_one_replacement() {
     assert_eq!(std::fs::read_to_string(path).unwrap(), "new_long");
 }
 
+#[test]
+fn repeated_inserts_at_one_position_all_apply_once_per_entry() {
+    let tmp = tempfile::tempdir().unwrap();
+    let path = tmp.path().join("main.ts");
+    std::fs::write(&path, "f(").unwrap();
+    let docs = documents();
+    let close = TextEdit { range: Range::new(Pos::new(0, 2), Pos::new(0, 2)), new_text: ")".into() };
+    let entry = FileEdit::Edit { path: path.clone().into(), version: None, edits: vec![close.clone(), close] };
+    docs.apply_workspace_edit(&WorkspaceEdit { files: vec![entry.clone(), entry], ..Default::default() }).unwrap();
+    assert_eq!(std::fs::read_to_string(&path).unwrap(), "f())");
+}
+
 #[test]
 fn undo_accepts_typing_that_was_reverted_to_the_saved_refactoring() {
     let tmp = tempfile::tempdir().unwrap();

docs/en/languages/index.mdx

@@ -11,9 +11,10 @@ Each open file gets its language from the definitions, checked in this order:
 
 1. A per-file **Override File Type** (in the context menu of a file in the project tree or of an editor tab).
 2. An exact file name (`Dockerfile`, `go.mod`) or a file name pattern.
-3. The extension, longest match first (`.html.erb` before `.erb`).
-4. The first line: a shebang such as `#!/usr/bin/env python3`, or a pattern such as `<?php`.
-5. Otherwise the file is plain text.
+3. A framework's folder: an `.html` or `.txt` file in a `templates` folder with a `manage.py` above it is a Django template.
+4. The extension, longest match first (`.html.erb` before `.erb`).
+5. The first line: a shebang such as `#!/usr/bin/env python3`, or a pattern such as `<?php`.
+6. Otherwise the file is plain text.
 
 You can add or remove file name patterns per language in **Settings › Editor › File Types** (**Recognized File Types**).
 
@@ -106,6 +107,7 @@ The table lists every built-in language definition. Server and debugger names in
 | D                   | `d`                | `.d`, `.di`                                                 | Yes          | —           | serve-d                                                                               | —                        |
 | Dart                | `dart`             | `.dart`                                                     | Yes          | Yes         | dart                                                                                  | dart                     |
 | Diff                | `diff`             | `.diff`, `.patch`, `.rej`                                   | Yes          | —           | —                                                                                     | —                        |
+| Django Template     | `django-html`      | `.djhtml`, `templates/*.html`, `*.txt`                      | Yes          | Yes         | **vscode-html-language-server**                                                       | —                        |
 | Dockerfile          | `dockerfile`       | `.dockerfile`, `.containerfile`                             | Yes          | —           | **dockerfile-language-server**                                                        | —                        |
 | Elixir              | `elixir`           | `.ex`, `.exs`                                               | Yes          | Yes         | **elixir-ls**                                                                         | **elixir-ls-debugger**   |
 | ERB                 | `erb`              | `.erb`, `.html.erb`, `.rhtml`, `.js.erb`, `.text.erb`, …    | Yes          | —           | —                                                                                     | —                        |

docs/en/languages/python.mdx

@@ -125,6 +125,12 @@ See [Debugging](/en/guide/debugging) for breakpoints, stepping and the debugger
 
 Django is the only framework with dedicated support: the `manage.py runserver` and `manage.py test` configurations, the **Django tests** configuration type (target, settings module, options), running single `TestCase` tests from the gutter, and Django mode in the debugger. Other frameworks (Flask, FastAPI and so on) run as ordinary scripts or console scripts.
 
+### Django templates
+
+The HTML and text files in a `templates` folder of a Django project (one with a `manage.py` above it) open as **Django Template** files: the template tags, variables, filters and comments are highlighted on top of the HTML, and block tags (`{% block %}`, `{% if %}`, `{% for %}`, `{% with %}` and the others of Django and its contrib libraries) fold, indent their content and highlight their end tag. Typing `{%`, `{{` or `{#` closes the pair, finishing a block tag adds its end tag, and `{% end` completes the end tags of the open blocks. **Comment with Line Comment** puts each line in its own `{# … #}`, and **Comment with Block Comment** over several lines uses `{% comment %}`. The HTML language server and Emmet work in the markup between the tags.
+
+An HTML file elsewhere with Django tags shows a banner that switches it to Django Template or keeps it as HTML; either choice is the file's **Override File Type**.
+
 ## Limitations
 
 - Only one type checker runs at a time. Ruff runs only in projects with a Ruff configuration.

docs/en/reference/settings.mdx

@@ -52,7 +52,6 @@ exclude = ["**/.git", "**/node_modules", "**/target", "**/dist"]
 | Editor                       | General (Auto Import, Appearance, Breadcrumbs, Code Completion, Code Folding, Editor Tabs, Gutter Icons, Inline Completion, Postfix Completion, Rich-Text Copy, Smart Keys, Sticky Lines); Code Editing; Font; Color Scheme; Code Style; Inspections; Natural Languages (Spelling); File and Code Templates; File Encodings; Live Templates; File Types; Inlay Hints; TODO; Vim |
 | Plugins                      | Plugins                                                                                                                                                                                                                                                                                                                                                                         |
 | Version Control              | Commit; Confirmation; Directory Mappings; Issue Navigation; Log; Shelf; Git; GitHub                                                                                                                                                                                                                                                                                             |
-| Project Structure            | Project Structure                                                                                                                                                                                                                                                                                                                                                               |
 | Build, Execution, Deployment | CMake; Gradle; Maven; Console; Debugger (Data Views, Stepping); Python Debugger; Run/Debug; Run Targets; Deployment (Options)                                                                                                                                                                                                                                                   |
 | Languages & Frameworks       | Language Servers; Go (Build Tags, Go Modules); Java; Markdown; Node.js; PHP; Python Interpreter; Prettier; oxfmt; Ruff; Ruby; Rust; TypeScript                                                                                                                                                                                                                                  |
 | Tools                        | Agents (Chat); Terminal; Actions on Save; External Tools; SSH Configurations; MCP Server                                                                                                                                                                                                                                                                                        |

docs/zh/languages/index.mdx

@@ -11,9 +11,10 @@ OpenIDEA 用一个小的定义文件 `languages/<id>.toml` 描述每种语言：
 
 1. 单个文件的 **覆盖文件类型**（在项目树中文件的右键菜单或编辑器标签页的右键菜单里）。
 2. 精确文件名（`Dockerfile`、`go.mod`）或文件名模式。
-3. 扩展名，优先匹配最长的（`.html.erb` 先于 `.erb`）。
-4. 文件第一行：例如 `#!/usr/bin/env python3` 这样的 shebang，或 `<?php` 这类模式。
-5. 都不匹配时按纯文本处理。
+3. 框架目录：上层目录有 `manage.py` 的 `templates` 目录中的 `.html` 或 `.txt` 文件是 Django 模板。
+4. 扩展名，优先匹配最长的（`.html.erb` 先于 `.erb`）。
+5. 文件第一行：例如 `#!/usr/bin/env python3` 这样的 shebang，或 `<?php` 这类模式。
+6. 都不匹配时按纯文本处理。
 
 在 **设置 › 编辑器 › 文件类型**（**已识别的文件类型**）中可以为某种语言添加或移除文件名模式。
 
@@ -101,6 +102,7 @@ IDE 安装工具从不需要 `sudo`。工具装在本地数据目录下 IDE 自
 | D                   | `d`                | `.d`, `.di`                                                 | 是   | —           | serve-d                                                                               | —                        |
 | Dart                | `dart`             | `.dart`                                                     | 是   | 是          | dart                                                                                  | dart                     |
 | Diff                | `diff`             | `.diff`, `.patch`, `.rej`                                   | 是   | —           | —                                                                                     | —                        |
+| Django Template     | `django-html`      | `.djhtml`, `templates/*.html`, `*.txt`                      | 是   | 是          | **vscode-html-language-server**                                                       | —                        |
 | Dockerfile          | `dockerfile`       | `.dockerfile`, `.containerfile`                             | 是   | —           | **dockerfile-language-server**                                                        | —                        |
 | Elixir              | `elixir`           | `.ex`, `.exs`                                               | 是   | 是          | **elixir-ls**                                                                         | **elixir-ls-debugger**   |
 | ERB                 | `erb`              | `.erb`, `.html.erb`, `.rhtml`, `.js.erb`, `.text.erb`, …    | 是   | —           | —                                                                                     | —                        |

docs/zh/languages/python.mdx

@@ -125,6 +125,12 @@ Python 调试使用 debugpy。开始调试时如果缺少 debugpy，OpenIDEA 会
 
 目前只有 Django 有专门支持：`manage.py runserver` 和 `manage.py test` 运行配置、**Django 测试** 配置类型（目标、settings 模块、选项）、在左侧栏运行单个 `TestCase` 测试，以及调试器的 Django 模式。Flask、FastAPI 等其他框架按普通脚本或命令行入口运行。
 
+### Django 模板
+
+Django 项目（上层目录有 `manage.py`）中 `templates` 目录里的 HTML 和文本文件以 **Django Template** 打开：模板标签、变量、过滤器和注释在 HTML 之上高亮，块标签（`{% block %}`、`{% if %}`、`{% for %}`、`{% with %}` 以及 Django 和其 contrib 库的其他块标签）可以折叠、缩进内容并高亮对应的结束标签。输入 `{%`、`{{` 或 `{#` 会自动补全成对符号，写完块标签会自动添加结束标签，输入 `{% end` 会补全当前打开块的结束标签。**使用行注释** 会把每一行放进各自的 `{# … #}`，多行的 **使用块注释** 则用 `{% comment %}`。HTML 语言服务器和 Emmet 在标签之间的标记中照常工作。
+
+其他位置含有 Django 标签的 HTML 文件会显示一个横幅，可以切换为 Django Template 或保留为 HTML；两种选择都会成为该文件的 **覆盖文件类型**。
+
 ## 限制
 
 - 同一时间只运行一个类型检查器。Ruff 只在有 Ruff 配置的项目中运行。

docs/zh/reference/settings.mdx

@@ -52,7 +52,6 @@ exclude = ["**/.git", "**/node_modules", "**/target", "**/dist"]
 | 编辑器           | 常规（自动导入、外观、痕迹导航、代码补全、代码折叠、编辑器标签页、装订区域图标、内联补全、后缀补全、富文本复制、智能键、粘滞行）；代码编辑；字体；配色方案；代码样式；检查；自然语言（拼写）；文件和代码模板；文件编码；实时模板；文件类型；嵌入提示；TODO；Vim |
 | 插件             | 插件                                                                                                                                                                                                                                                            |
 | 版本控制         | 提交；确认；目录映射；问题导航；日志；搁置；Git；GitHub                                                                                                                                                                                                         |
-| 项目结构         | 项目结构                                                                                                                                                                                                                                                        |
 | 构建、执行、部署 | CMake；Gradle；Maven；控制台；调试器（数据视图、单步执行）；Python 调试器；运行/调试；运行目标；部署（选项）                                                                                                                                                    |
 | 语言和框架       | 语言服务器；Go（构建标签、Go 模块）；Java；Markdown；Node.js；PHP；Python 解释器；Prettier；oxfmt；Ruff；Ruby；Rust；TypeScript                                                                                                                                 |
 | 工具             | 智能体（聊天）；终端；保存时操作；外部工具；SSH 配置；MCP 服务器                                                                                                                                                                                                |

e2e/settingsPaneLayout.spec.ts

@@ -85,16 +85,13 @@ for (const id of ["editor.fileTemplates", "editor.liveTemplates"]) {
 }
 
 test("Project Structure keeps every details pane usable in a compact window", async ({ workbench: page }) => {
-  await page.keyboard.press("Meta+,");
-  await expect(page.getByRole("dialog", { name: "Settings", exact: true })).toBeVisible();
-  await page.evaluate(async () => {
-    const path = "/src/features/settings/model/staging.ts";
-    (await import(/* @vite-ignore */ path)).selectPage("projectStructure");
-  });
+  await page.keyboard.press("Meta+;");
+  const dialog = page.getByRole("dialog", { name: "Project Structure", exact: true });
+  await expect(dialog).toBeVisible();
   await page.setViewportSize({ width: 520, height: 760 });
   for (const section of ["Modules", "Libraries", "Facets", "Artifacts", "SDKs"]) {
-    await page.getByRole("tab", { name: section, exact: true }).click();
-    const details = page.locator("[class*='splitLayout'] > [class*='detailPane']");
+    await dialog.getByRole("button", { name: section, exact: true }).click();
+    const details = dialog.locator("[class*='splitLayout'] > [class*='detailPane']");
     await expect(details).toBeAttached();
     expect((await details.boundingBox())!.width).toBeGreaterThan(200);
   }

e2e/terminal-ui.spec.ts

@@ -93,6 +93,36 @@ test("terminal highlights visible occurrences of selected text in a single overl
     activeSession()!.term.clearSelection();
   });
   await expect(terminal.locator(".openidea-terminal-selection-match:visible")).toHaveCount(0);
+
+  // Full-scrollback trim shifts a visible match into the cached margin row above viewportY; scrolling up must highlight it.
+  await page.evaluate(async () => {
+    const path = "/src/features/terminal/runtime.ts";
+    const { activeSession } = await import(path);
+    const s = activeSession()!;
+    const rows = s.term.rows;
+    s.term.options.scrollback = 4;
+    s.term.reset();
+    const total = rows + 4;
+    let payload = "";
+    for (let i = 0; i < total - 1; i++) {
+      payload += `${i === 4 ? "needle hit" : `row-${i}`}\r\n`;
+    }
+    payload += "needle sel";
+    await new Promise<void>((resolve) => s.term.write(payload, resolve));
+    s.term.select(0, total - 1, 6);
+  });
+  await expect(terminal.locator(".openidea-terminal-selection-match:visible")).toHaveCount(1);
+
+  await page.evaluate(async () => {
+    await new Promise((r) => setTimeout(r, 100));
+    const path = "/src/features/terminal/runtime.ts";
+    const { activeSession } = await import(path);
+    const s = activeSession()!;
+    await new Promise<void>((resolve) => s.term.write("\r\nnext", resolve));
+    s.term.scrollLines(-1);
+  });
+  await expect(terminal.locator(".openidea-terminal-selection-match:visible")).toHaveCount(1);
+  await expect(terminal.locator(".openidea-terminal-selection-match:visible")).toHaveCSS("top", "0px");
 });
 
 test("terminal ⌘F highlights active/inactive search matches and seeds with a new selection", async ({

fixtures/README.md

@@ -15,6 +15,7 @@ something to show.
 | `java-app/`      | JDK 21, Maven 3.9                                               | `mvn compile exec:java`             | `mvn test`           | `mvn test -DopenideaFail=true`            | unused variable in `App.java`                            |
 | `c-app/`         | gcc / g++ 12+, make, GDB 14+                                    | `make all`                          | —                    | —                                     | —                                                        |
 | `php-app/`       | PHP 8.5, Composer                                               | `composer quote`                    | `vendor/bin/pest`    | `OPENIDEA_FAIL=1 vendor/bin/pest`         | unused variable in `ThresholdCustoms.php`                |
+| `django-app/`    | Python 3.10+, Django 5.2+                                       | `python manage.py runserver`        | `python manage.py test` | `OPENIDEA_FAIL=1 python manage.py test` | unused import in `shop/views.py`                         |
 | `polyglot/`      | Go, TS, Python, C, shell, SQL, TOML/YAML/JSON, proto, Terraform | `make`                              | `make test`          | —                                     | unused variable in `native/hash.c`                       |
 
 The fixtures are standalone: `rust-app` declares its own `[workspace]` and

fixtures/django-app/config/settings.py

@@ -0,0 +1,27 @@
+"""Settings of the shop fixture: one app, no database tables of its own."""
+
+from pathlib import Path
+
+BASE_DIR = Path(__file__).resolve().parent.parent
+
+SECRET_KEY = "fixture-only-not-a-secret"
+DEBUG = True
+ALLOWED_HOSTS = ["localhost", "127.0.0.1"]
+
+INSTALLED_APPS = ["django.contrib.staticfiles", "shop"]
+
+ROOT_URLCONF = "config.urls"
+
+TEMPLATES = [
+    {
+        "BACKEND": "django.template.backends.django.DjangoTemplates",
+        "DIRS": [],
+        "APP_DIRS": True,
+        "OPTIONS": {"context_processors": ["django.template.context_processors.request"]},
+    }
+]
+
+DATABASES = {"default": {"ENGINE": "django.db.backends.sqlite3", "NAME": ":memory:"}}
+
+STATIC_URL = "static/"
+USE_TZ = True

fixtures/django-app/config/urls.py

@@ -0,0 +1,3 @@
+from django.urls import include, path
+
+urlpatterns = [path("", include("shop.urls"))]

fixtures/django-app/manage.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+"""Django's command-line utility for the shop fixture."""
+
+import os
+import sys
+
+
+def main() -> None:
+    os.environ.setdefault("DJANGO_SETTINGS_MODULE", "config.settings")
+    from django.core.management import execute_from_command_line
+
+    execute_from_command_line(sys.argv)
+
+
+if __name__ == "__main__":
+    main()

fixtures/django-app/pages/promo.html

@@ -0,0 +1,4 @@
+<!-- Not in a templates folder: the editor offers Django Template from its tags. -->
+{% load static %}
+<p>Two cappuccini for <strong>{{ price|default:"€3" }}</strong></p>
+<img src="{% static 'promo.png' %}" alt="">

fixtures/django-app/requirements.txt

@@ -0,0 +1 @@
+Django>=5.2

fixtures/django-app/shop/templates/shop/base.html

@@ -0,0 +1,15 @@
+{% load static %}<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <title>{% block title %}Shop{% endblock %}</title>
+    <link rel="stylesheet" href="{% static 'shop/site.css' %}">
+  </head>
+  <body>
+    {# The navigation is the same on every page. #}
+    <nav><a href="{% url 'shop:products' %}">Menu</a></nav>
+    <main>
+      {% block content %}{% endblock content %}
+    </main>
+  </body>
+</html>

fixtures/django-app/shop/templates/shop/email/order.txt

@@ -0,0 +1,3 @@
+{% autoescape off %}Thank you for your order, {{ name|default:"customer" }}!
+{% for line in lines %}- {{ line.quantity }} × {{ line.product.name }}
+{% endfor %}{% endautoescape %}

fixtures/django-app/shop/templates/shop/product_list.html

@@ -0,0 +1,25 @@
+{% extends "shop/base.html" %}
+
+{% block title %}{% if single %}{{ products.0.name }}{% else %}Menu{% endif %} · {{ block.super }}{% endblock %}
+
+{% block content %}
+  <ul class="products">
+    {% for product in products %}
+      <li class="{% cycle 'odd' 'even' %}">
+        <a href="{% url 'shop:product' slug=product.slug %}">{{ product.name|title }}</a>
+        <span class="price">€{{ product.price|floatformat:2 }}</span>
+        {% with count=product.tags|length %}
+          {% if count > 1 %}
+            <small>{{ product.tags|join:", " }}</small>
+          {% endif %}
+        {% endwith %}
+      </li>
+    {% empty %}
+      <li>Nothing on the menu today.</li>
+    {% endfor %}
+  </ul>
+  {% comment "Ideas" %}
+    <p>{{ seasonal_specials }}</p>
+  {% endcomment %}
+  {% verbatim %}<script type="text/x-template">{{ clientSide }}</script>{% endverbatim %}
+{% endblock content %}

fixtures/django-app/shop/tests.py

@@ -0,0 +1,22 @@
+import os
+import unittest
+
+from django.test import SimpleTestCase
+from django.urls import reverse
+
+
+class ProductPagesTests(SimpleTestCase):
+    def test_lists_every_product(self):
+        response = self.client.get(reverse("shop:products"))
+        self.assertContains(response, "Espresso")
+        self.assertContains(response, "Cornetto")
+        self.assertContains(response, "€1.60")
+
+    def test_unknown_product_is_not_found(self):
+        response = self.client.get(reverse("shop:product", args=["tea"]))
+        self.assertEqual(response.status_code, 404)
+
+    @unittest.skipUnless(os.environ.get("OPENIDEA_FAIL"), "opt-in failing test")
+    def test_intentionally_failing(self):
+        # FIXME: the opt-in failing test, for the test runner's failure views.
+        self.assertContains(self.client.get(reverse("shop:products")), "Tea")

fixtures/django-app/shop/urls.py

@@ -0,0 +1,10 @@
+from django.urls import path
+
+from . import views
+
+app_name = "shop"
+
+urlpatterns = [
+    path("", views.product_list, name="products"),
+    path("products/<slug:slug>/", views.product_detail, name="product"),
+]

fixtures/django-app/shop/views.py

@@ -0,0 +1,35 @@
+"""Views of the shop: a product list and a product page."""
+
+import json  # Intentional warning: unused import.
+from dataclasses import dataclass
+from decimal import Decimal
+
+from django.http import Http404, HttpRequest, HttpResponse
+from django.shortcuts import render
+
+
+@dataclass(frozen=True)
+class Product:
+    slug: str
+    name: str
+    price: Decimal
+    tags: tuple[str, ...] = ()
+
+
+PRODUCTS = [
+    Product("espresso", "Espresso", Decimal("1.20"), ("coffee", "hot")),
+    Product("cappuccino", "Cappuccino", Decimal("1.60"), ("coffee", "milk")),
+    Product("cornetto", "Cornetto", Decimal("1.30")),
+]
+
+
+def product_list(request: HttpRequest) -> HttpResponse:
+    # TODO: paginate once the menu grows.
+    return render(request, "shop/product_list.html", {"products": PRODUCTS})
+
+
+def product_detail(request: HttpRequest, slug: str) -> HttpResponse:
+    product = next((p for p in PRODUCTS if p.slug == slug), None)  # Set a breakpoint here
+    if product is None:
+        raise Http404(slug)
+    return render(request, "shop/product_list.html", {"products": [product], "single": True})

java/java-usages/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: OpenIDEA Java usages
 Bundle-SymbolicName: ai.openidea.usages;singleton:=true
-Bundle-Version: 1.12.0
+Bundle-Version: 1.13.0
 Bundle-RequiredExecutionEnvironment: JavaSE-21
 Require-Bundle: org.eclipse.jdt.ls.core,org.eclipse.jdt.core,
  org.eclipse.jdt.core.manipulation,org.eclipse.core.runtime,

java/java-usages/README.md

@@ -88,7 +88,7 @@ is not a claim of full IntelliJ feature parity.
 ## Rebuild and delivery
 
 The checked-in jar is embedded by ide-sdk `include_bytes!`, installed as
-`java-usages-1.12.0.jar`, and added alongside existing initialization bundles.
+`java-usages-1.13.0.jar`, and added alongside existing initialization bundles.
 Users need no compiler, Maven or Python. Manifest/install version must change
 when replacing the bundle because OSGi caches bundles.
 

java/java-usages/src/ai/openidea/Documents.java

@@ -0,0 +1,21 @@
+package ai.openidea;
+
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.OperationCanceledException;
+import org.eclipse.jdt.ls.core.internal.JobHelpers;
+import org.eclipse.jdt.ls.core.internal.handlers.BaseDocumentLifeCycleHandler;
+
+/** What a command that reads an editor's position needs before it resolves the position. */
+public final class Documents {
+    private Documents() {}
+
+    /**
+     * Waits for the queued document changes to be reconciled, as JDT LS's own position requests
+     * do: `workspace/executeCommand` does not, so a position sent right after an edit would
+     * be resolved against the element structure from before it.
+     */
+    public static void awaitChanges(IProgressMonitor monitor) {
+        JobHelpers.waitForJobs(BaseDocumentLifeCycleHandler.DOCUMENT_LIFE_CYCLE_JOBS, monitor);
+        if (monitor.isCanceled()) throw new OperationCanceledException();
+    }
+}

java/java-usages/src/ai/openidea/configuration/ConfigurationCommand.java

@@ -1,5 +1,6 @@
 package ai.openidea.configuration;
 
+import ai.openidea.Documents;
 import java.net.URI;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -96,6 +97,7 @@ public final class ConfigurationCommand implements IDelegateCommandHandler {
     @Override
     public Object executeCommand(String command, List<Object> args, IProgressMonitor monitor) throws Exception {
         if (command.equals("openidea.java.configuration.warmup")) return ConfigurationWarmup.request(args);
+        Documents.awaitChanges(monitor);
         String uri = (String) args.get(0);
         String key = args.get(1) instanceof String s ? s : null;
         int line = ((Number) args.get(2)).intValue(), column = ((Number) args.get(3)).intValue();

java/java-usages/src/ai/openidea/hierarchy/HierarchyCommand.java

@@ -1,5 +1,6 @@
 package ai.openidea.hierarchy;
 
+import ai.openidea.Documents;
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -44,6 +45,7 @@ public final class HierarchyCommand implements IDelegateCommandHandler {
 
     @Override
     public Object executeCommand(String command, List<Object> arguments, IProgressMonitor monitor) throws Exception {
+        Documents.awaitChanges(monitor);
         String uri = (String) arguments.get(0);
         int line = ((Number) arguments.get(1)).intValue();
         int column = ((Number) arguments.get(2)).intValue();

java/java-usages/src/ai/openidea/implementations/ImplementationsCommand.java

@@ -1,5 +1,6 @@
 package ai.openidea.implementations;
 
+import ai.openidea.Documents;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
@@ -27,6 +28,7 @@ public final class ImplementationsCommand implements IDelegateCommandHandler {
 
     @Override
     public Object executeCommand(String command, List<Object> arguments, IProgressMonitor monitor) throws Exception {
+        Documents.awaitChanges(monitor);
         List<Location> locations = new ArrayList<>();
         boolean complete = find(arguments, locations, monitor);
         return Map.of("locations", locations, "complete", complete);

java/java-usages/src/ai/openidea/usages/UsagesCommand.java

@@ -1,5 +1,6 @@
 package ai.openidea.usages;
 
+import ai.openidea.Documents;
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
@@ -29,6 +30,7 @@ import org.eclipse.lsp4j.*;
 public final class UsagesCommand implements IDelegateCommandHandler {
     @Override
     public Object executeCommand(String command, List<Object> arguments, IProgressMonitor monitor) throws Exception {
+        Documents.awaitChanges(monitor);
         String uri = (String) arguments.get(0);
         int line = ((Number) arguments.get(1)).intValue();
         int column = ((Number) arguments.get(2)).intValue();

languages/django-html.toml

@@ -0,0 +1,23 @@
+id = "django-html"
+name = "Django Template"
+extensions = ["djhtml"]
+block-comment = ["{#", "#}"]
+indent = { tab-size = 2, insert-spaces = true }
+ui-mode = "Django Template"
+tree-sitter = "html"
+
+# Django projects: the HTML and text files in a `templates` folder.
+[[framework-files]]
+folder = "templates"
+extensions = ["html", "txt"]
+root-markers = ["manage.py"]
+
+# The markup between the template tags: completion and hover of tags and
+# attributes. The template tags are text to it. No formatter: HTML formatters
+# reflow template tags.
+[[language-servers]]
+name = "vscode-html-language-server"
+command = "vscode-html-language-server"
+args = ["--stdio"]
+initialization-options = { embeddedLanguages = { css = true, javascript = true } }
+install-hint = "npm i -g vscode-langservers-extracted"

languages/go.toml

@@ -17,7 +17,7 @@ func main() {
 [[language-servers]]
 name = "gopls"
 command = "gopls"
-initialization-options = { semanticTokens = true }
+initialization-options = { semanticTokens = true, vulncheck = "Imports" }
 root-markers = ["go.work", "go.mod"]
 install-hint = "go install golang.org/x/tools/gopls@latest"
 

languages/gomod.toml

@@ -8,6 +8,6 @@ ui-mode = "GoMod"
 [[language-servers]]
 name = "gopls"
 command = "gopls"
-initialization-options = { semanticTokens = true }
+initialization-options = { semanticTokens = true, vulncheck = "Imports" }
 root-markers = ["go.work", "go.mod"]
 install-hint = "go install golang.org/x/tools/gopls@latest"

languages/gowork.toml

@@ -8,6 +8,6 @@ ui-mode = "GoMod"
 [[language-servers]]
 name = "gopls"
 command = "gopls"
-initialization-options = { semanticTokens = true }
+initialization-options = { semanticTokens = true, vulncheck = "Imports" }
 root-markers = ["go.work"]
 install-hint = "go install golang.org/x/tools/gopls@latest"

package.json

@@ -22,6 +22,7 @@
     "gen:windows-icons": "node scripts/gen-windows-icons.ts",
     "gen:angular-grammar": "lezer-generator src/editor/core/cm/angular/angular.grammar --typeScript -o src/editor/core/cm/angular/parser.ts",
     "gen:jsp-grammar": "lezer-generator src/editor/core/cm/jsp/jsp.grammar --typeScript -o src/editor/core/cm/jsp/parser.ts",
+    "gen:django-grammar": "lezer-generator src/editor/core/cm/django/django.grammar --typeScript -o src/editor/core/cm/django/parser.ts",
     "gen:astro-grammar": "lezer-generator src/editor/core/cm/astro/astro.grammar --typeScript -o src/editor/core/cm/astro/parser.ts",
     "gen:theme-docs": "node scripts/theme/gen-docs.ts",
     "theme:import-intellij": "node scripts/theme/import-intellij-theme.ts",

src-tauri/Cargo.toml

@@ -108,6 +108,7 @@ windows = { version = "0.62", features = [
 windows-sys = { version = "0.61", features = [
     "Win32_Foundation",
     "Win32_Graphics_Gdi",
+    "Win32_UI_Input_KeyboardAndMouse",
     "Win32_UI_Shell",
     "Win32_UI_WindowsAndMessaging",
 ] }

src-tauri/src/commands/deploy.rs

@@ -128,6 +128,19 @@ pub async fn remote_mkdir(state: State<'_, AppState>, connection: FsConnection,
     ide_host::ops::deploy::remote_mkdir(&state.host, connection, path).await
 }
 
+#[tauri::command]
+#[specta::specta]
+pub async fn remote_download_into(
+    window: Window,
+    state: State<'_, AppState>,
+    connection: FsConnection,
+    paths: Vec<String>,
+    target: IpcPath,
+    request: RequestId,
+) -> IdeResult<TransferReport> {
+    ide_host::ops::deploy::remote_download_into(window.label(), &state.host, connection, paths, target, request).await
+}
+
 #[tauri::command]
 #[specta::specta]
 pub async fn remote_rename(

src-tauri/src/commands/doc.rs

@@ -163,12 +163,14 @@ pub async fn doc_selection_ranges(
 
 #[tauri::command]
 #[specta::specta]
-pub fn history_list(window: Window, state: State<'_, AppState>, path: PathBuf) -> IdeResult<Vec<HistoryEntry>> {
-    ide_host::ops::doc::history_list(&state.host, window.label(), path)
+pub async fn history_list(window: Window, state: State<'_, AppState>, path: PathBuf) -> IdeResult<Vec<HistoryEntry>> {
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::doc::history_list(&host, &label, path)).await
 }
 
 #[tauri::command]
 #[specta::specta]
-pub fn history_content(window: Window, state: State<'_, AppState>, id: String) -> IdeResult<String> {
-    ide_host::ops::doc::history_content(&state.host, window.label(), id)
+pub async fn history_content(window: Window, state: State<'_, AppState>, id: String) -> IdeResult<String> {
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::doc::history_content(&host, &label, id)).await
 }

src-tauri/src/commands/hotkeys.rs

@@ -0,0 +1,189 @@
+//! Detects shortcuts the OS already gave to another app (Windows only).
+//!
+//! Some vendors register system-wide hotkeys (e.g. NVIDIA's overlay grabs
+//! `Alt+R` / `Alt+Shift+R`), so those keystrokes never reach the IDE. Probing
+//! asks Windows to register each combo for an instant: success means it is
+//! free (released right away), `ERROR_HOTKEY_ALREADY_REGISTERED` means another
+//! app grabbed it. Nothing is left registered.
+
+use ide_core::IdeResult;
+
+/// Reports which of `combos` (single-stroke `Alt+Shift+R`-style bindings) are
+/// already registered to another app. Empty everywhere but Windows.
+#[tauri::command]
+#[specta::specta]
+pub fn system_probe_hotkeys(combos: Vec<String>) -> IdeResult<Vec<String>> {
+    Ok(combos.into_iter().filter(|combo| imp::grabbed(combo)).collect())
+}
+
+/// A parsed binding: `RegisterHotKey` modifiers plus a virtual-key code.
+#[cfg(windows)]
+struct Hotkey {
+    modifiers: u32,
+    vk: u32,
+}
+
+/// Splits a canonical single-stroke binding into modifiers and key; `None`
+/// for chords, double-modifier gestures, mouse buttons and unknown keys.
+#[cfg(windows)]
+fn parse_combo(combo: &str) -> Option<Hotkey> {
+    use windows_sys::Win32::UI::Input::KeyboardAndMouse::{MOD_ALT, MOD_CONTROL, MOD_SHIFT, MOD_WIN};
+
+    if combo.contains(' ') {
+        return None;
+    }
+    let mut parts = combo.split('+');
+    let key = parts.next_back()?;
+    let mut modifiers = 0;
+    for part in parts {
+        modifiers |= match part.to_ascii_uppercase().as_str() {
+            "CTRL" => MOD_CONTROL,
+            "ALT" => MOD_ALT,
+            "SHIFT" => MOD_SHIFT,
+            "META" => MOD_WIN,
+            _ => return None,
+        };
+    }
+    if modifiers == 0 {
+        return None;
+    }
+    Some(Hotkey { modifiers, vk: vk_of(key)? })
+}
+
+/// The virtual-key code of a binding key, or `None` when it has no single
+/// `RegisterHotKey` code (mouse buttons, gestures, layout-dependent keys).
+#[cfg(windows)]
+fn vk_of(key: &str) -> Option<u32> {
+    if key.len() == 1 {
+        let c = key.as_bytes()[0].to_ascii_uppercase();
+        if c.is_ascii_alphanumeric() {
+            return Some(u32::from(c));
+        }
+        return match c {
+            b'-' => Some(0xBD),
+            b'=' => Some(0xBB),
+            b'[' => Some(0xDB),
+            b']' => Some(0xDD),
+            b'\\' => Some(0xDC),
+            b';' => Some(0xBA),
+            b'\'' => Some(0xDE),
+            b',' => Some(0xBC),
+            b'.' => Some(0xBE),
+            b'/' => Some(0xBF),
+            b'`' => Some(0xC0),
+            _ => None,
+        };
+    }
+    // "F13" → 0x7C … "F24" → 0x87; anything else falls through to the names below.
+    let fkey =
+        key.strip_prefix('F').and_then(|n| n.parse::<u32>().ok()).filter(|n| (1..=24).contains(n)).map(|n| 0x6F + n);
+    if fkey.is_some() {
+        return fkey;
+    }
+    match key.to_ascii_uppercase().as_str() {
+        "SPACE" => Some(0x20),
+        "ENTER" | "RETURN" => Some(0x0D),
+        "ESCAPE" | "ESC" => Some(0x1B),
+        "TAB" => Some(0x09),
+        "BACKSPACE" | "BACK" => Some(0x08),
+        "DELETE" | "DEL" => Some(0x2E),
+        "INSERT" | "INS" => Some(0x2D),
+        "HOME" => Some(0x24),
+        "END" => Some(0x23),
+        "PAGEUP" | "PRIOR" => Some(0x21),
+        "PAGEDOWN" | "NEXT" => Some(0x22),
+        "UP" => Some(0x26),
+        "DOWN" => Some(0x28),
+        "LEFT" => Some(0x25),
+        "RIGHT" => Some(0x27),
+        _ => None,
+    }
+}
+
+#[cfg(windows)]
+mod imp {
+    use super::{Hotkey, parse_combo};
+    use std::sync::atomic::{AtomicI32, Ordering};
+    use windows_sys::Win32::Foundation::{ERROR_HOTKEY_ALREADY_REGISTERED, GetLastError};
+    use windows_sys::Win32::UI::Input::KeyboardAndMouse::{RegisterHotKey, UnregisterHotKey};
+
+    /// Probe ids (never shown, never left registered).
+    static NEXT_ID: AtomicI32 = AtomicI32::new(0x1DEA00);
+
+    /// Registers `combo` for an instant: grabbed iff Windows refuses with
+    /// `ERROR_HOTKEY_ALREADY_REGISTERED`. A granted registration is released
+    /// before returning, so probing never steals a shortcut.
+    pub(super) fn grabbed(combo: &str) -> bool {
+        let Some(Hotkey { modifiers, vk }) = parse_combo(combo) else {
+            return false;
+        };
+        // SAFETY: registering a hotkey to a null window only tests availability;
+        // the id is unique per probe and unregistered on success.
+        unsafe {
+            let id = NEXT_ID.fetch_add(1, Ordering::Relaxed);
+            if RegisterHotKey(std::ptr::null_mut(), id, modifiers, vk) != 0 {
+                UnregisterHotKey(std::ptr::null_mut(), id);
+                false
+            } else {
+                GetLastError() == ERROR_HOTKEY_ALREADY_REGISTERED
+            }
+        }
+    }
+}
+
+#[cfg(not(windows))]
+mod imp {
+    /// No other platform lets background apps swallow our keystrokes this way.
+    pub(super) fn grabbed(_combo: &str) -> bool {
+        false
+    }
+}
+
+#[cfg(all(test, windows))]
+mod tests {
+    use super::imp::grabbed;
+    use super::parse_combo;
+    use windows_sys::Win32::Foundation::{ERROR_HOTKEY_ALREADY_REGISTERED, GetLastError};
+    use windows_sys::Win32::UI::Input::KeyboardAndMouse::{MOD_ALT, MOD_SHIFT, RegisterHotKey, UnregisterHotKey};
+
+    #[test]
+    fn parses_modifier_order_and_key() {
+        let hotkey = parse_combo("Alt+Shift+R").expect("Alt+Shift+R parses");
+        assert_eq!(hotkey.modifiers, MOD_ALT | MOD_SHIFT);
+        assert_eq!(hotkey.vk, u32::from(b'R'));
+        let f7 = parse_combo("Alt+F7").expect("Alt+F7 parses");
+        assert_eq!(f7.modifiers, MOD_ALT);
+        assert_eq!(f7.vk, 0x76);
+    }
+
+    #[test]
+    fn rejects_what_cannot_be_probed() {
+        for combo in ["R", "Alt+R Alt+S", "Shift Shift", "Alt+Button4", "Ctrl+Foo", ""] {
+            assert!(!grabbed(combo), "{combo} must not probe");
+        }
+    }
+
+    /// Holds a real hotkey, then the probe must report it as grabbed — whether
+    /// our hold succeeded or another app already held it (both read 1409).
+    #[test]
+    fn sees_a_hotkey_held_by_another_registration() {
+        const COMBO: &str = "Alt+Shift+F24";
+        const VK_F24: u32 = 0x87;
+        // SAFETY: a test-only registration, released below.
+        let held = unsafe { RegisterHotKey(std::ptr::null_mut(), 0x1DEAFE, MOD_ALT | MOD_SHIFT, VK_F24) != 0 };
+        if !held {
+            assert_eq!(
+                unsafe { GetLastError() },
+                ERROR_HOTKEY_ALREADY_REGISTERED,
+                "the test hotkey must be holdable or already held"
+            );
+        }
+        assert!(grabbed(COMBO), "a held hotkey reads as grabbed");
+        if held {
+            // SAFETY: releases the registration above.
+            unsafe {
+                UnregisterHotKey(std::ptr::null_mut(), 0x1DEAFE);
+            }
+        }
+    }
+}

src-tauri/src/commands/mod.rs

@@ -28,6 +28,7 @@ pub mod fs;
 pub mod github;
 pub mod heap;
 pub mod history;
+pub mod hotkeys;
 pub mod http;
 pub mod java;
 pub mod lsp;
@@ -218,6 +219,7 @@ pub fn builder() -> tauri_specta::Builder<tauri::Wry> {
         history::history_list_dir,
         history::history_put_label,
         history::history_restore,
+        hotkeys::system_probe_hotkeys,
         refactor::refactor_file_move_edits,
         refactor::refactor_file_move_text_edits,
         refactor::refactor_move_files,
@@ -685,6 +687,7 @@ pub fn builder() -> tauri_specta::Builder<tauri::Wry> {
         deploy::remote_of,
         deploy::remote_delete,
         deploy::remote_mkdir,
+        deploy::remote_download_into,
         deploy::remote_rename,
         crate::remote_dev::remote_bootstrap_list,
         crate::remote_dev::remote_connect,

src-tauri/src/commands/run.rs

@@ -1,5 +1,6 @@
 //! IPC commands of `ide_host::ops::run` (the shared implementation).
 
+use super::doc::blocking;
 use crate::state::AppState;
 use ide_core::{IdeResult, RunId};
 #[allow(unused_imports)]
@@ -55,13 +56,15 @@ pub async fn run_configs(window: Window, state: State<'_, AppState>) -> IdeResul
 
 #[tauri::command]
 #[specta::specta]
-pub fn run_save_configs(
+pub async fn run_save_configs(
     window: Window,
     state: State<'_, AppState>,
     configs: Vec<RunConfig>,
     removed_detected_ids: Option<Vec<String>>,
 ) -> IdeResult<()> {
-    ide_host::ops::run::save_configs(&state.host, window.label(), &configs, &removed_detected_ids.unwrap_or_default())
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    let removed = removed_detected_ids.unwrap_or_default();
+    blocking(move || ide_host::ops::run::save_configs(&host, &label, &configs, &removed)).await
 }
 
 /// Temporary configurations as they are kept between sessions: without what settings derived.
@@ -140,36 +143,44 @@ pub fn run_close_stdin(state: State<'_, AppState>, id: RunId) -> IdeResult<()> {
 /// Configuration templates: per-type defaults applied to new configurations.
 #[tauri::command]
 #[specta::specta]
-pub fn run_templates(window: Window, state: State<'_, AppState>) -> IdeResult<Vec<RunConfig>> {
-    ide_host::ops::run::run_templates(&state.host, window.label())
+pub async fn run_templates(window: Window, state: State<'_, AppState>) -> IdeResult<Vec<RunConfig>> {
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::run::run_templates(&host, &label)).await
 }
 
 #[tauri::command]
 #[specta::specta]
-pub fn run_save_templates(window: Window, state: State<'_, AppState>, templates: Vec<RunConfig>) -> IdeResult<()> {
-    ide_host::ops::run::run_save_templates(&state.host, window.label(), templates)
+pub async fn run_save_templates(
+    window: Window,
+    state: State<'_, AppState>,
+    templates: Vec<RunConfig>,
+) -> IdeResult<()> {
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::run::run_save_templates(&host, &label, templates)).await
 }
 
 /// Project files run configurations can be imported from (`.vscode/launch.json`).
 #[tauri::command]
 #[specta::specta]
-pub fn run_import_sources(
+pub async fn run_import_sources(
     window: Window,
     state: State<'_, AppState>,
 ) -> IdeResult<Vec<ide_run::import::RunImportSource>> {
-    ide_host::ops::run::run_import_sources(&state.host, window.label())
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::run::run_import_sources(&host, &label)).await
 }
 
 /// Configurations read from `source`, not saved; names already in `existing` are skipped.
 #[tauri::command]
 #[specta::specta]
-pub fn run_import_configs(
+pub async fn run_import_configs(
     window: Window,
     state: State<'_, AppState>,
     source: ide_run::import::RunImportSource,
     existing: Vec<RunConfig>,
 ) -> IdeResult<ide_run::import::RunImport> {
-    ide_host::ops::run::run_import_configs(&state.host, window.label(), source, existing)
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::run::run_import_configs(&host, &label, source, existing)).await
 }
 
 /// The environment runs inherit when "Include system environment variables" is on.
@@ -182,12 +193,13 @@ pub fn run_system_env(state: State<'_, AppState>) -> std::collections::BTreeMap<
 /// Variables of the `.env` files a debug launch names, for the debugger to start with.
 #[tauri::command]
 #[specta::specta]
-pub fn run_env_files(
+pub async fn run_env_files(
     window: Window,
     state: State<'_, AppState>,
     files: Vec<std::path::PathBuf>,
 ) -> IdeResult<std::collections::BTreeMap<String, String>> {
-    ide_host::ops::run::run_env_files(&state.host, window.label(), files)
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::run::run_env_files(&host, &label, files)).await
 }
 
 /// Writes the Gradle init script adding `jvm_args` to the JVMs the build forks; returns its path.

src-tauri/src/commands/vcs.rs

@@ -1,5 +1,6 @@
 //! IPC commands of `ide_host::ops::vcs` (the shared implementation).
 
+use super::doc::blocking;
 use crate::state::AppState;
 use ide_core::{IdeResult, RequestId};
 #[allow(unused_imports)]
@@ -7,7 +8,7 @@ pub use ide_host::ops::vcs::*;
 use ide_vcs::*;
 use std::path::PathBuf;
 use tauri::ipc::Channel;
-use tauri::{State, Window};
+use tauri::{AppHandle, Manager, State, Window};
 
 /// Changes of every repository of the project.
 #[tauri::command]
@@ -473,8 +474,12 @@ pub async fn vcs_diff_text(
 /// Line hunks between two arbitrary texts (diff viewer, commit dialog).
 #[tauri::command]
 #[specta::specta]
-pub fn vcs_diff_hunks(state: State<'_, AppState>, old_text: String, new_text: String) -> Vec<LineHunk> {
-    ide_host::ops::vcs::vcs_diff_hunks(&state.host, "", old_text, new_text)
+pub async fn vcs_diff_hunks(app: AppHandle, old_text: String, new_text: String) -> Vec<LineHunk> {
+    // Off the main thread: diffing two large texts would freeze the window.
+    let host = app.state::<AppState>().host.clone();
+    tauri::async_runtime::spawn_blocking(move || ide_host::ops::vcs::vcs_diff_hunks(&host, "", old_text, new_text))
+        .await
+        .expect("line diff panicked")
 }
 
 /// Stages only the selected hunks of a file's working-tree changes.
@@ -783,8 +788,9 @@ pub async fn vcs_shelve(
 
 #[tauri::command]
 #[specta::specta]
-pub fn vcs_shelves(window: Window, state: State<'_, AppState>) -> IdeResult<Vec<ShelvedChangeList>> {
-    ide_host::ops::vcs::vcs_shelves(&state.host, window.label())
+pub async fn vcs_shelves(window: Window, state: State<'_, AppState>) -> IdeResult<Vec<ShelvedChangeList>> {
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::vcs::vcs_shelves(&host, &label)).await
 }
 
 /// Unshelve: applies the shelved patch (3-way merging; conflicts are left for the
@@ -803,33 +809,44 @@ pub async fn vcs_unshelve(
 
 #[tauri::command]
 #[specta::specta]
-pub fn vcs_shelf_delete(window: Window, state: State<'_, AppState>, id: String, path: Option<String>) -> IdeResult<()> {
-    ide_host::ops::vcs::vcs_shelf_delete(&state.host, window.label(), id, path)
+pub async fn vcs_shelf_delete(
+    window: Window,
+    state: State<'_, AppState>,
+    id: String,
+    path: Option<String>,
+) -> IdeResult<()> {
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::vcs::vcs_shelf_delete(&host, &label, id, path)).await
 }
 
 #[tauri::command]
 #[specta::specta]
-pub fn vcs_shelf_rename(window: Window, state: State<'_, AppState>, id: String, name: String) -> IdeResult<()> {
-    ide_host::ops::vcs::vcs_shelf_rename(&state.host, window.label(), id, name)
+pub async fn vcs_shelf_rename(window: Window, state: State<'_, AppState>, id: String, name: String) -> IdeResult<()> {
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::vcs::vcs_shelf_rename(&host, &label, id, name)).await
 }
 
 #[tauri::command]
 #[specta::specta]
-pub fn vcs_shelf_patch(
+pub async fn vcs_shelf_patch(
     window: Window,
     state: State<'_, AppState>,
     id: String,
     path: Option<String>,
 ) -> IdeResult<String> {
-    ide_host::ops::vcs::vcs_shelf_patch(&state.host, window.label(), id, path)
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::vcs::vcs_shelf_patch(&host, &label, id, path)).await
 }
 
 #[tauri::command]
 #[specta::specta]
-pub fn vcs_changelists_load(window: Window, state: State<'_, AppState>) -> IdeResult<ChangelistState> {
-    ide_host::ops::vcs::vcs_changelists_load(&state.host, window.label())
+pub async fn vcs_changelists_load(window: Window, state: State<'_, AppState>) -> IdeResult<ChangelistState> {
+    let (host, label) = (state.host.clone(), window.label().to_owned());
+    blocking(move || ide_host::ops::vcs::vcs_changelists_load(&host, &label)).await
 }
 
+// Synchronous on purpose: the UI saves without waiting (debounced), and on the main thread
+// the saves land in order, so an older state can't overwrite a newer one.
 #[tauri::command]
 #[specta::specta]
 pub fn vcs_changelists_save(window: Window, state: State<'_, AppState>, changelists: ChangelistState) -> IdeResult<()> {

src-tauri/tests/blocking_commands.rs

@@ -0,0 +1,46 @@
+//! Tauri runs a command declared without `async` on the main thread, so disk I/O or a
+//! large diff there freezes the window (input, painting, every other IPC call).
+
+/// Commands that read or write project files, Local History or `.env` files, or diff two
+/// arbitrary texts: they must be `async` and do that work on the blocking pool.
+const OFF_MAIN_THREAD: &[(&str, &[&str])] = &[
+    ("doc.rs", &["history_list", "history_content"]),
+    (
+        "vcs.rs",
+        &[
+            "vcs_diff_hunks",
+            "vcs_shelves",
+            "vcs_shelf_delete",
+            "vcs_shelf_rename",
+            "vcs_shelf_patch",
+            "vcs_changelists_load",
+        ],
+    ),
+    (
+        "run.rs",
+        &[
+            "run_save_configs",
+            "run_templates",
+            "run_save_templates",
+            "run_import_sources",
+            "run_import_configs",
+            "run_env_files",
+        ],
+    ),
+];
+
+#[test]
+fn disk_and_diff_commands_stay_off_the_main_thread() {
+    let dir = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("src/commands");
+    let mut on_main = Vec::new();
+    for (file, commands) in OFF_MAIN_THREAD {
+        let source = std::fs::read_to_string(dir.join(file)).unwrap();
+        for command in *commands {
+            assert!(source.contains(&format!("fn {command}(")), "{file} has no command {command}");
+            if !source.contains(&format!("pub async fn {command}(")) {
+                on_main.push(*command);
+            }
+        }
+    }
+    assert!(on_main.is_empty(), "synchronous commands run on the main thread: {on_main:?}");
+}

src/bindings.ts

@@ -381,6 +381,11 @@ export const commands = {
 	 *  file and its folders); an open editor updates in place.
 	 */
 	historyRestore: (path: string, id: string) => typedError<null, IdeError>(__TAURI_INVOKE("history_restore", { path, id })),
+	/**
+	 *  Reports which of `combos` (single-stroke `Alt+Shift+R`-style bindings) are
+	 *  already registered to another app. Empty everywhere but Windows.
+	 */
+	systemProbeHotkeys: (combos: string[]) => typedError<string[], IdeError>(__TAURI_INVOKE("system_probe_hotkeys", { combos })),
 	/**  `workspace/willRenameFiles` on every interested server (before the move). Cancellable. */
 	refactorFileMoveEdits: (request: RequestId, moves: FileMove[]) => typedError<FileRenameEdits, IdeError>(__TAURI_INVOKE("refactor_file_move_edits", { request, moves })),
 	/**
@@ -1571,6 +1576,7 @@ export const commands = {
 	remoteOf: (path: IpcPath) => __TAURI_INVOKE<[FsConnection, string] | null>("remote_of", { path }),
 	remoteDelete: (connection: FsConnection, path: string) => typedError<null, IdeError>(__TAURI_INVOKE("remote_delete", { connection, path })),
 	remoteMkdir: (connection: FsConnection, path: string) => typedError<null, IdeError>(__TAURI_INVOKE("remote_mkdir", { connection, path })),
+	remoteDownloadInto: (connection: FsConnection, paths: string[], target: IpcPath, request: RequestId) => typedError<TransferReport, IdeError>(__TAURI_INVOKE("remote_download_into", { connection, paths, target, request })),
 	remoteRename: (connection: FsConnection, from: string, to: string) => typedError<null, IdeError>(__TAURI_INVOKE("remote_rename", { connection, from, to })),
 	/**  Browse before connecting, using the desktop's SSH configuration even in a remote window. */
 	remoteBootstrapList: (ssh: string, path: string) => typedError<RemoteEntry[], IdeError>(__TAURI_INVOKE("remote_bootstrap_list", { ssh, path })),
@@ -4177,6 +4183,13 @@ export type DocumentInfo = {
 	lineEnding: LineEnding,
 	readOnly: boolean,
 	dirty: boolean,
+	/**
+	 *  Whether "Reload with Encoding" can re-decode this document's source
+	 *  bytes: true for files and virtual documents the backend can re-read
+	 *  (archive entries, JDT sources with an editable attachment encoding,
+	 *  Git revisions); false for server-generated content (decompiled code).
+	 */
+	canReloadEncoding: boolean,
 	/**
 	 *  Larger than `ide_vfs::LARGE_FILE_THRESHOLD`: language servers, syntax
 	 *  structure and folding are disabled; the editor should drop heavy features.
@@ -9970,6 +9983,18 @@ export type VirtualDocument = {
 	description: string | null,
 	/**  Generated Java from a decompiler, rather than real source or a disassembler stub. */
 	decompiled: boolean,
+	/**
+	 *  Charset the content was decoded with (a WHATWG label, e.g. `gbk`);
+	 *  `utf-8` for text the server decoded itself.
+	 */
+	encoding: string,
+	hasBom: boolean,
+	/**
+	 *  "Reload with Encoding" can re-decode the origin's bytes (archive
+	 *  entries, JDT sources with an editable attachment encoding); false for
+	 *  server-generated content such as decompiled code.
+	 */
+	canReloadEncoding: boolean,
 };
 
 /**  Declared (or conventional) visibility of an outline symbol. */

src/editor/core/backend.ts

@@ -396,6 +396,7 @@ export function createMemoryBackend(files: Record<string, string> = {}): MemoryB
     lineEnding: d.lineEnding,
     readOnly: d.readOnly,
     dirty: d.text !== d.saved || d.hasBom !== d.savedBom,
+    canReloadEncoding: !d.uri,
     ...(d.uri ? { uri: d.uri } : {}),
     ...(d.uiMode ? { uiMode: d.uiMode } : {}),
   });

src/editor/core/cm/comments.ts

@@ -81,7 +81,10 @@ export const commentLine: Command = (view) => {
     lineToken(state, doc.line(b.startLine).from + leadingWs(doc.line(b.startLine).text)),
   );
   // Languages without line comments (CSS, HTML…): block comments.
-  if (tokens.some((t) => !t)) return blockCommentLines(view);
+  if (tokens.some((t) => !t)) {
+    const first = doc.line(blocks[0]!.startLine);
+    return lineBound(state, first.from + leadingWs(first.text)) ? commentEachLine(view) : blockCommentLines(view);
+  }
 
   let allCommented = true;
   let commentedNonEmpty = false;
@@ -348,11 +351,92 @@ function uncommentBlock(view: EditorView, ranges: { from: number; to: number }[]
 
 /** ⌘⇧/: block comments the selection, or takes the block comment back out. */
 export const commentBlock: Command = (view) => {
-  if (view.state.readOnly) return false;
-  const ranges = view.state.selection.ranges.map((r) => ({ from: r.from, to: r.to }));
-  return uncommentBlock(view, ranges) || toggleBlockComment(view);
+  const { state } = view;
+  if (state.readOnly) return false;
+  const ranges = state.selection.ranges.map((r) => ({ from: r.from, to: r.to }));
+  if (uncommentBlock(view, ranges)) return true;
+  const multiline = state.selection.ranges.some(
+    (r) => state.doc.lineAt(r.from).number != state.doc.lineAt(r.to).number,
+  );
+  const bound = multiline ? lineBound(state, state.selection.main.from) : null;
+  if (!bound) return toggleBlockComment(view);
+  const { open, close } = bound.multiline;
+  view.dispatch(
+    state.changeByRange((r) => ({
+      changes: [
+        { from: r.from, insert: open },
+        { from: r.to, insert: close },
+      ],
+      range: EditorSelection.range(r.from + open.length, r.to + open.length),
+    })),
+    { scrollIntoView: true, userEvent: "input.comment" },
+  );
+  return true;
 };
 
+/**
+ * Language data `lineBoundComments` of a language whose block comment can't span lines
+ * (Django's `{# #}`): `multiline` is the comment to use across lines.
+ */
+interface LineBoundComments {
+  multiline: CommentPair;
+}
+
+function lineBound(state: EditorState, pos: number): LineBoundComments | null {
+  return state.languageDataAt<LineBoundComments>("lineBoundComments", pos)[0] ?? null;
+}
+
+/**
+ * ⌘/ where a block comment can't span lines: each non-blank line gets its own, or loses it
+ * when every one has one. A caret alone moves down, as with line comments.
+ */
+function commentEachLine(view: EditorView): boolean {
+  const { state } = view;
+  const doc = state.doc;
+  const lines = new Set<number>();
+  for (const r of state.selection.ranges) {
+    const first = doc.lineAt(r.from).number;
+    let last = doc.lineAt(r.to).number;
+    if (last > first && doc.line(last).from === r.to) last--;
+    for (let n = first; n <= last; n++) lines.add(n);
+  }
+  const targets = [...lines]
+    .sort((a, b) => a - b)
+    .map((n) => doc.line(n))
+    .filter((line) => line.text.trim());
+  const pairs = targets.map((line) => commentPairs(state, line.from + leadingWs(line.text))[0]);
+  if (!targets.length || pairs.some((p) => !p)) return blockCommentLines(view);
+  const commented = targets.every((line, i) => {
+    const text = line.text.trim();
+    return text.startsWith(pairs[i]!.open) && text.endsWith(pairs[i]!.close);
+  });
+  const changes: ChangeSpec[] = targets.map((line, i) => {
+    const { open, close } = pairs[i]!;
+    const start = line.from + leadingWs(line.text);
+    const end = line.from + line.text.trimEnd().length;
+    if (!commented)
+      return [
+        { from: start, insert: `${open} ` },
+        { from: end, insert: ` ${close}` },
+      ];
+    const inner = state.sliceDoc(start + open.length, end - close.length);
+    return { from: start, to: end, insert: inner.replace(/^ /, "").replace(/ $/, "") };
+  });
+  const caret = state.selection.ranges.length === 1 && state.selection.main.empty;
+  const changeSet = state.changes(changes);
+  const next = caret ? doc.lineAt(state.selection.main.head).number + 1 : 0;
+  view.dispatch({
+    changes: changeSet,
+    selection:
+      caret && next <= doc.lines
+        ? EditorSelection.cursor(changeSet.mapPos(doc.line(next).from + leadingWs(doc.line(next).text)))
+        : state.selection.map(changeSet),
+    scrollIntoView: true,
+    userEvent: commented ? "delete.uncomment" : "input.comment",
+  });
+  return true;
+}
+
 /** ⌘/ in a language without line comments (CSS, HTML…): the block comment of the lines. */
 function blockCommentLines(view: EditorView): boolean {
   const ranges = selectedLines(view.state);

src/editor/core/cm/django/django.grammar

@@ -0,0 +1,112 @@
+// Django templates: the template layer. Tags (`{% … %}`), variables (`{{ … }}`)
+// and comments are parsed here; the text between them is HTML, mounted by
+// `./index.ts`. Block tags of Django and its contrib libraries nest
+// (`{% if %}…{% elif %}…{% endif %}`); other tags, custom ones included, stand
+// alone. Regenerate with `pnpm gen:django-grammar`.
+
+@context blocks from "./tokens"
+
+@top Template { node* }
+
+node {
+  Text |
+  Comment |
+  Interpolation |
+  Tag |
+  Element |
+  CommentElement |
+  VerbatimElement
+}
+
+// A block tag, its middle tags (`elif`, `else`, `empty`, `plural`) and its end tag.
+Element { OpenTag node* (MidTag node*)* EndTag }
+
+// `{% comment %}…{% endcomment %}`: the content is not parsed.
+CommentElement { CommentTag CommentBody? EndTag }
+
+// `{% verbatim %}…{% endverbatim %}`: the content is HTML whose tags and
+// variables Django leaves alone.
+VerbatimElement { VerbatimTag VerbatimBody? EndTag }
+
+@skip { space } {
+  OpenTag { OpenTagStart TagName argument* TagEnd }
+  CommentTag { CommentTagStart TagName argument* TagEnd }
+  VerbatimTag { VerbatimTagStart TagName argument* TagEnd }
+  MidTag { MidTagStart TagName argument* TagEnd }
+  EndTag { EndTagStart TagName argument* TagEnd }
+  Tag { TagStart TagName argument* TagEnd }
+
+  Interpolation { "{{" expression? "}}" }
+
+  argument {
+    expression |
+    CompareOp |
+    AssignOp { "=" } |
+    kw<"and"> | kw<"or"> | kw<"not"> | kw<"in"> | kw<"is"> |
+    kw<"as"> | kw<"with"> | kw<"only"> | kw<"from">
+  }
+
+  expression[@isGroup=Expression] {
+    VariableName |
+    MemberExpression |
+    String |
+    Number |
+    @specialize[@name=BooleanLiteral]<identifier, "True" | "False"> |
+    @specialize[@name=None]<identifier, "None"> |
+    FilterExpression
+  }
+
+  MemberExpression { (VariableName | MemberExpression) "." (PropertyName | Number) }
+
+  FilterExpression { expression !filter FilterOp FilterName (":" filterArgument)? }
+
+  filterArgument { VariableName | MemberExpression | String | Number }
+}
+
+@precedence { filter @left }
+
+VariableName { identifier }
+
+PropertyName { identifier }
+
+FilterName { identifier }
+
+// `with` is a keyword in arguments and a block tag's name.
+TagName { identifier | kw<"with"> }
+
+FilterOp { "|" }
+
+TagEnd { "%}" }
+
+kw<term> { @specialize[@name={term}]<identifier, term> }
+
+// Tried in this order, before the tokens below: a raw block's content before
+// the tags in it.
+@external tokens comment from "./tokens" { Comment }
+@external tokens commentBody from "./tokens" { CommentBody }
+@external tokens verbatimBody from "./tokens" { VerbatimBody }
+@external tokens text from "./tokens" { Text }
+@external tokens tagStart from "./tokens" {
+  OpenTagStart, CommentTagStart, VerbatimTagStart, MidTagStart, EndTagStart, TagStart
+}
+
+@tokens {
+  space { $[ \t\n\r]+ }
+
+  identifier { $[a-zA-Z_\u{a1}-\u{10ffff}] $[a-zA-Z0-9_\u{a1}-\u{10ffff}]* }
+
+  Number { "-"? @digit+ ("." @digit+)? }
+
+  String {
+    '"' (!["\\] | "\\" _)* '"'? |
+    "'" (!['\\] | "\\" _)* "'"?
+  }
+
+  CompareOp { "==" | "!=" | "<" | ">" | "<=" | ">=" }
+
+  @precedence { CompareOp, "=" }
+
+  "{{" "}}" "." ":" "="
+}
+
+@detectDelim

src/editor/core/cm/django/django.test.ts

@@ -0,0 +1,251 @@
+import { describe, expect, it } from "vitest";
+import { readFileSync } from "node:fs";
+import { resolve } from "node:path";
+import { EditorSelection, EditorState } from "@codemirror/state";
+import { EditorView } from "@codemirror/view";
+import { CompletionContext, type CompletionResult, type CompletionSource } from "@codemirror/autocomplete";
+import { foldable, getIndentation, indentUnit, matchBrackets } from "@codemirror/language";
+import { buildParserFile } from "@lezer/generator";
+import { highlightTree, tagHighlighter, tags as t } from "@lezer/highlight";
+import { completedSyntaxState, completedSyntaxTree } from "@/test/syntax";
+import { commentBlock, commentLine } from "../comments";
+import { findLanguageDescription, loadSupport } from "../languages";
+import { django, djangoLanguage } from "./index";
+
+const highlighter = tagHighlighter([
+  { tag: t.special(t.brace), class: "delim" },
+  { tag: t.blockComment, class: "comment" },
+  { tag: t.operatorKeyword, class: "opkw" },
+  { tag: t.keyword, class: "keyword" },
+  { tag: t.bool, class: "bool" },
+  { tag: t.null, class: "null" },
+  { tag: t.function(t.variableName), class: "filter" },
+  { tag: t.variableName, class: "var" },
+  { tag: t.propertyName, class: "prop" },
+  { tag: t.attributeName, class: "attr" },
+  { tag: t.string, class: "str" },
+  { tag: t.number, class: "num" },
+  { tag: t.tagName, class: "tag" },
+]);
+
+function state(doc: string, selection?: EditorSelection | number): EditorState {
+  return completedSyntaxState(
+    EditorState.create({
+      doc,
+      selection: typeof selection == "number" ? EditorSelection.cursor(selection) : selection,
+      extensions: [django(), indentUnit.of("  ")],
+    }),
+  );
+}
+
+/** `text:class` of the styled tokens of `doc`, HTML included. */
+function tokens(doc: string): string[] {
+  const out: string[] = [];
+  highlightTree(completedSyntaxTree(state(doc)), highlighter, (from, to, cls) =>
+    out.push(`${doc.slice(from, to)}:${cls}`),
+  );
+  return out;
+}
+
+/** The error nodes of `doc`'s template layer, with the text they start. */
+function errors(doc: string): string[] {
+  const out: string[] = [];
+  djangoLanguage.parser.parse(doc).iterate({
+    enter: (node) => void (node.type.isError && out.push(doc.slice(node.from, node.from + 12))),
+  });
+  return out;
+}
+
+/** The top-level node names of `doc`'s template layer. */
+function outline(doc: string): string {
+  return djangoLanguage.parser.parse(doc).toString();
+}
+
+/** A view on `doc` with `|` marking the caret. */
+function view(marked: string): EditorView {
+  const at = marked.indexOf("|");
+  const doc = marked.slice(0, at) + marked.slice(at + 1);
+  return new EditorView({ state: state(doc, at) });
+}
+
+/** Types `text` at the caret through the input handlers, like a keystroke. */
+function type(v: EditorView, text: string): string {
+  const { from, to } = v.state.selection.main;
+  const handled = v.state.facet(EditorView.inputHandler).some((h) => h(v, from, to, text, () => v.state.update({})));
+  if (!handled)
+    v.dispatch({ changes: { from, to, insert: text }, selection: EditorSelection.cursor(from + text.length) });
+  const head = v.state.selection.main.head;
+  return v.state.sliceDoc(0, head) + "|" + v.state.sliceDoc(head);
+}
+
+describe("Django template grammar", () => {
+  it("parses Django's tags, filters with arguments and its operators without errors", () => {
+    const doc = [
+      `{% extends "base.html" %}{% load static i18n %}`,
+      `{% block content %}{{ block.super }}`,
+      `<a href="{% url 'app:detail' pk=obj.pk as link %}">{{ value|date:"Y-m-d"|default:'-' }}</a>`,
+      `<img src="{% static 'img/a.png' %}">{% csrf_token %}`,
+      `{% for x in items|dictsort:"name" %}{{ forloop.counter0 }} {{ x.0 }}{% empty %}none{% endfor %}`,
+      `{% if a and not b or c in d %}x{% elif e is not None and n >= -1 %}y{% else %}z{% endif %}`,
+      `{% blocktranslate with n=count trimmed %}{{ n }} item{% plural %}{{ n }} items{% endblocktranslate %}`,
+      `{% with total=business.employees.count %}{{ total }}{% endwith %}`,
+      `{% include "row.html" with item=item only %}{% cycle 'odd' 'even' %}{% now "Y" %}`,
+      `{% render_field form.email class="input" %}{% endblock content %}`,
+    ].join("\n");
+    expect(errors(doc)).toEqual([]);
+  });
+
+  it("nests block tags and leaves other tags alone", () => {
+    expect(outline("{% if a %}{% for x in b %}{{ x }}{% endfor %}{% else %}-{% endif %}")).toBe(
+      "Template(Element(OpenTag(OpenTagStart,TagName,VariableName,TagEnd)," +
+        "Element(OpenTag(OpenTagStart,TagName,VariableName,in,VariableName,TagEnd)," +
+        'Interpolation("{{",VariableName,"}}"),EndTag(EndTagStart,TagName,TagEnd)),' +
+        "MidTag(MidTagStart,TagName,TagEnd),Text,EndTag(EndTagStart,TagName,TagEnd)))",
+    );
+    expect(outline("{% csrf_token %}{% else %}")).toBe(
+      "Template(Tag(TagStart,TagName,TagEnd),Tag(TagStart,TagName,TagEnd))",
+    );
+  });
+
+  it("closes a block only with its own end tag", () => {
+    // `endfor` closes nothing here: the `if` stays open to the end.
+    const tree = outline("{% if a %}{% endfor %}");
+    expect(tree).toContain("Element(OpenTag(");
+    expect(tree).toContain("Tag(TagStart,TagName,TagEnd)");
+  });
+
+  it("doesn't parse the content of comment and verbatim", () => {
+    expect(errors("{% comment 'why' %}{% if %} {{ {% endcomment %}")).toEqual([]);
+    expect(outline("{% verbatim %}{{ raw }}{% if %}{% endverbatim %}")).toBe(
+      "Template(VerbatimElement(VerbatimTag(VerbatimTagStart,TagName,TagEnd),VerbatimBody,EndTag(EndTagStart,TagName,TagEnd)))",
+    );
+  });
+
+  it("highlights the template layer and the markup around it", () => {
+    expect(tokens(`<p class="x">{{ user.name|lower }}{# hi #}</p>`)).toEqual([
+      "p:tag",
+      "class:attr",
+      '"x":str',
+      "{{:delim",
+      "user:var",
+      "name:prop",
+      "lower:filter",
+      "}}:delim",
+      "{# hi #}:comment",
+      "p:tag",
+    ]);
+    expect(tokens(`{% if a is None and b %}{% endif %}`)).toEqual([
+      "{%:delim",
+      "if:keyword",
+      "a:var",
+      "is:opkw",
+      "None:null",
+      "and:opkw",
+      "b:var",
+      "%}:delim",
+      "{%:delim",
+      "endif:keyword",
+      "%}:delim",
+    ]);
+  });
+
+  it("parses the templates of the Django fixture without errors", () => {
+    const fixture = resolve(import.meta.dirname, "../../../../../fixtures/django-app");
+    for (const file of [
+      "shop/templates/shop/base.html",
+      "shop/templates/shop/product_list.html",
+      "shop/templates/shop/email/order.txt",
+      "pages/promo.html",
+    ]) {
+      expect([file, errors(readFileSync(resolve(fixture, file), "utf8"))]).toEqual([file, []]);
+    }
+  });
+
+  it("is generated from django.grammar", () => {
+    const dir = import.meta.dirname;
+    const { parser, terms } = buildParserFile(readFileSync(resolve(dir, "django.grammar"), "utf8"), {
+      fileName: "src/editor/core/cm/django/django.grammar",
+      moduleStyle: "es",
+      typeScript: true,
+    });
+    expect(parser).toBe(readFileSync(resolve(dir, "parser.ts"), "utf8"));
+    expect(terms).toBe(readFileSync(resolve(dir, "parser.terms.ts"), "utf8"));
+  });
+});
+
+describe("Django template editing", () => {
+  it("folds blocks, comments and verbatim content", () => {
+    const doc = "{% block content %}\n  <p>x</p>\n{% endblock %}\n{% comment %}\nold\n{% endcomment %}\n";
+    const s = state(doc);
+    expect(foldable(s, 0, doc.indexOf("\n"))).toEqual({ from: doc.indexOf("%}") + 2, to: doc.indexOf("{% endblock") });
+    const comment = doc.indexOf("{% comment");
+    expect(foldable(s, comment, doc.indexOf("\n", comment))).toEqual({
+      from: doc.indexOf("%}", comment) + 2,
+      to: doc.indexOf("{% endcomment"),
+    });
+  });
+
+  it("indents a block's content and puts its middle and end tags back", () => {
+    const doc = "{% if a %}\nx\n{% else %}\ny\n{% endif %}";
+    const s = state(doc);
+    const lineStart = (n: number) => s.doc.line(n).from;
+    expect(getIndentation(s, lineStart(2))).toBe(2);
+    expect(getIndentation(s, lineStart(3))).toBe(0);
+    expect(getIndentation(s, lineStart(5))).toBe(0);
+  });
+
+  it("matches a block tag with its end tag by name", () => {
+    const doc = "{% for x in xs %}{{ x }}{% endfor %}";
+    const match = matchBrackets(state(doc), 4, 1);
+    expect(match?.matched).toBe(true);
+    expect(doc.slice(match!.end!.from, match!.end!.to)).toBe("endfor");
+  });
+
+  it("closes {% %}, {{ }} and {# #} after a brace", () => {
+    expect(type(view("<p>{|</p>"), "%")).toBe("<p>{% | %}</p>");
+    expect(type(view("<p>{|}</p>"), "{")).toBe("<p>{{ | }}</p>");
+    expect(type(view("{|"), "#")).toBe("{# | #}");
+    // Not in a script, where `{` is JavaScript's.
+    expect(type(view("<script>let a = {|</script>"), "{")).toBe("<script>let a = {{|</script>");
+  });
+
+  it("adds the end tag of a block tag when its %} is typed", () => {
+    expect(type(view("{% block content %|"), "}")).toBe("{% block content %}|{% endblock %}");
+    expect(type(view("{% if a %|}"), "}")).toBe("{% if a %}|{% endif %}");
+    // It has one already.
+    expect(type(view("{% if a %|\n{% endif %}"), "}")).toBe("{% if a %}|\n{% endif %}");
+    expect(type(view("{% if a %|{% if b %}{% endif %}"), "}")).toBe("{% if a %}|{% endif %}{% if b %}{% endif %}");
+    // Not a block tag.
+    expect(type(view("{% csrf_token %|"), "}")).toBe("{% csrf_token %}|");
+  });
+
+  it("completes the end tags of the open blocks, innermost first", () => {
+    const doc = "{% block a %}{% for x in y %}{% end";
+    const s = state(doc);
+    const sources = s.languageDataAt<CompletionSource>("autocomplete", doc.length);
+    const result = sources.map((src) => src(new CompletionContext(s, doc.length, false))).find(Boolean) as
+      | CompletionResult
+      | undefined;
+    expect(result?.options.map((o) => o.label)).toEqual(["endfor", "endblock"]);
+  });
+
+  it("comments each line with {# #}, and several lines with a comment tag", () => {
+    const v = view("|<p>a</p>\n  <p>b</p>");
+    v.dispatch({ selection: EditorSelection.range(0, v.state.doc.length) });
+    commentLine(v);
+    expect(v.state.doc.toString()).toBe("{# <p>a</p> #}\n  {# <p>b</p> #}");
+    v.dispatch({ selection: EditorSelection.range(0, v.state.doc.length) });
+    commentLine(v);
+    expect(v.state.doc.toString()).toBe("<p>a</p>\n  <p>b</p>");
+    v.dispatch({ selection: EditorSelection.range(0, v.state.doc.length) });
+    commentBlock(v);
+    expect(v.state.doc.toString()).toBe("{% comment %}<p>a</p>\n  <p>b</p>{% endcomment %}");
+    commentBlock(v);
+    expect(v.state.doc.toString()).toBe("<p>a</p>\n  <p>b</p>");
+  });
+
+  it("is the Django Template mode", async () => {
+    const desc = findLanguageDescription("Django Template", "/p/templates/index.html");
+    expect((await loadSupport(desc!))?.language).toBe(djangoLanguage);
+  });
+});

src/editor/core/cm/django/index.ts

@@ -0,0 +1,223 @@
+/**
+ * Django templates: `django.grammar` parses the template layer (tags,
+ * variables, comments), and the text between its elements is one HTML
+ * document, an overlay as in JSP, so markup split by a tag still nests and
+ * `href="{% url 'home' %}"` is an attribute with a hole. Block tags fold,
+ * indent their content and match their end tags; typing `{%`, `{{` or `{#`
+ * closes the pair, and finishing a block tag adds its end tag.
+ */
+import {
+  LRLanguage,
+  LanguageSupport,
+  bracketMatchingHandle,
+  foldNodeProp,
+  indentNodeProp,
+  syntaxTree,
+  type TreeIndentContext,
+} from "@codemirror/language";
+import { html } from "@codemirror/lang-html";
+import type { CompletionContext, CompletionResult } from "@codemirror/autocomplete";
+import { EditorSelection, Prec, type EditorState } from "@codemirror/state";
+import { EditorView } from "@codemirror/view";
+import { styleTags, tags as t } from "@lezer/highlight";
+import { NodeProp, parseMixed, type SyntaxNode, type SyntaxNodeRef } from "@lezer/common";
+import { parser } from "./parser";
+import { BLOCK_TAGS } from "./tokens";
+
+export { BLOCK_TAGS };
+
+const baseHTML = html({ selfClosingTags: true });
+
+/** `{# #}` can't span lines: a multi-line block comment is a `comment` tag. */
+const DJANGO_COMMENT = { block: { open: "{#", close: "#}" } };
+const COMMENT_TAG = { open: "{% comment %}", close: "{% endcomment %}" };
+
+const OPENERS = ["OpenTag", "CommentTag", "VerbatimTag"];
+
+const startTagOf = (element: SyntaxNode) => element.firstChild;
+const endTagOf = (element: SyntaxNode) => (element.lastChild?.name == "EndTag" ? element.lastChild : null);
+
+/** The content of a block: from the end of its start tag to its end tag (or the end of the block). */
+function foldBlock(element: SyntaxNode, state: EditorState) {
+  const start = startTagOf(element);
+  const end = endTagOf(element);
+  if (!start) return null;
+  // An end tag the parser inserted to recover is empty.
+  const to = end && end.to > end.from ? end.from : element.to;
+  return start.to < to && state.doc.lineAt(start.to).number < state.doc.lineAt(to).number
+    ? { from: start.to, to }
+    : null;
+}
+
+const CLOSING_LINE = /^\s*\{%-?\s*(end\w*|elif|else|empty|plural)\b/;
+
+/** A block's content one unit in from its start tag's line; its middle and end tags at that line's indent. */
+function indentBlock(cx: TreeIndentContext) {
+  const start = startTagOf(cx.node);
+  if (!start) return null;
+  const base = cx.lineIndent(start.from);
+  return CLOSING_LINE.test(cx.textAfter) ? base : base + cx.unit;
+}
+
+const tagName = (node: SyntaxNode) => node.getChild("TagName");
+
+const templateParser = parser.configure({
+  props: [
+    styleTags({
+      'TagStart OpenTagStart CommentTagStart VerbatimTagStart MidTagStart EndTagStart TagEnd "{{" "}}"': t.special(
+        t.brace,
+      ),
+      TagName: t.keyword,
+      "Comment CommentBody": t.blockComment,
+      VariableName: t.variableName,
+      PropertyName: t.propertyName,
+      FilterName: t.function(t.variableName),
+      FilterOp: t.operator,
+      String: t.string,
+      Number: t.number,
+      BooleanLiteral: t.bool,
+      None: t.null,
+      CompareOp: t.compareOperator,
+      AssignOp: t.definitionOperator,
+      "and or not in is": t.operatorKeyword,
+      "as with only from": t.keyword,
+      '"."': t.derefOperator,
+      '":"': t.punctuation,
+    }),
+    foldNodeProp.add({
+      "Element CommentElement VerbatimElement": foldBlock,
+    }),
+    indentNodeProp.add({
+      Element: indentBlock,
+      // The raw content keeps its own indentation.
+      "CommentElement VerbatimElement": () => null,
+    }),
+    NodeProp.closedBy.add({ "OpenTag CommentTag VerbatimTag": ["EndTag"] }),
+    NodeProp.openedBy.add({ EndTag: OPENERS }),
+    bracketMatchingHandle.add({ "OpenTag CommentTag VerbatimTag EndTag": tagName }),
+  ],
+});
+
+// HTML's document gives no indentation past its last text; there the block around it does.
+const htmlBase = (baseHTML.language as LRLanguage).parser;
+const htmlDocumentIndent = htmlBase.nodeSet.types.find((type) => type.name == "Document")?.prop(indentNodeProp);
+const htmlParser = htmlBase.configure({
+  props: [indentNodeProp.add({ Document: (cx) => htmlDocumentIndent?.(cx) ?? cx.continue() })],
+});
+
+// The template text, and the content of `verbatim`, are one HTML document.
+const htmlMixed = {
+  parser: htmlParser,
+  overlay: (node: SyntaxNodeRef) => node.name == "Text" || node.name == "VerbatimBody",
+};
+
+export const djangoLanguage = LRLanguage.define({
+  name: "django",
+  parser: templateParser.configure({ wrap: parseMixed((node) => (node.type.isTop ? htmlMixed : null)) }),
+});
+
+/** Where the template layer reaches: Django's own nodes, or the HTML outside `<script>` and `<style>`. */
+function inTemplate(state: EditorState, pos: number): boolean {
+  return state.languageDataAt<boolean>("djangoTemplate", pos).includes(true);
+}
+
+const PAIRS: Record<string, string> = { "%": "%", "{": "}", "#": "#" };
+
+/**
+ * After a `{`, typing `%`, `{` or `#` makes the pair: `{% | %}`, `{{ | }}`, `{# | #}`. The
+ * `}` that closing brackets put after the first brace is reused.
+ */
+const closePair = EditorView.inputHandler.of((view, from, to, text) => {
+  const close = PAIRS[text];
+  const { state } = view;
+  if (!close || from != to || state.selection.ranges.length > 1 || state.readOnly) return false;
+  if (state.sliceDoc(from - 1, from) != "{" || state.sliceDoc(from - 2, from - 1) == "{") return false;
+  if (!inTemplate(state, from)) return false;
+  const reuse = state.sliceDoc(from, from + 1) == "}";
+  const insert = `${text}  ${close}${reuse ? "" : "}"}`;
+  view.dispatch({
+    changes: { from, insert },
+    selection: EditorSelection.cursor(from + text.length + 1),
+    userEvent: "input.type",
+  });
+  return true;
+});
+
+const TAG_BEFORE = /\{%-?\s*([A-Za-z_]\w*)[^%]*%$/;
+
+/** Whether the block `name` opened before `pos` has no end tag after it, nested blocks counted. */
+function unclosed(state: EditorState, name: string, pos: number): boolean {
+  const rest = state.sliceDoc(pos);
+  const re = new RegExp(`\\{%-?\\s*(end)?${name}\\b`, "g");
+  let depth = 0;
+  for (let m; (m = re.exec(rest));) {
+    if (!m[1]) depth++;
+    else if (depth-- == 0) return false;
+  }
+  return true;
+}
+
+/** Typing the `}` of a block tag's `%}` adds its end tag after the caret when it has none. */
+const closeBlock = EditorView.inputHandler.of((view, from, to, text) => {
+  const { state } = view;
+  if (text != "}" || from != to || state.selection.ranges.length > 1 || state.readOnly) return false;
+  const line = state.doc.lineAt(from);
+  const m = TAG_BEFORE.exec(state.sliceDoc(line.from, from));
+  const name = m?.[1];
+  if (!name || !BLOCK_TAGS.has(name) || !inTemplate(state, from - m[0].length)) return false;
+  // A `}` closing brackets put there is typed over.
+  const after = state.sliceDoc(from, from + 1) == "}" ? 1 : 0;
+  if (!unclosed(state, name, from + after)) return false;
+  view.dispatch({
+    changes: { from, to: from + after, insert: `}{% end${name} %}` },
+    selection: EditorSelection.cursor(from + 1),
+    userEvent: "input.type",
+  });
+  return true;
+});
+
+/** The blocks open at `pos`, innermost first. */
+function openBlocks(state: EditorState, pos: number): string[] {
+  const names: string[] = [];
+  for (let node: SyntaxNode | null = syntaxTree(state).resolve(pos, -1); node; node = node.parent) {
+    if (!/^(Element|CommentElement|VerbatimElement)$/.test(node.name)) continue;
+    const start = startTagOf(node);
+    const name = start && tagName(start);
+    if (start && name && start.to <= pos) names.push(state.sliceDoc(name.from, name.to));
+  }
+  return names;
+}
+
+/** `{% end…`: the end tags of the blocks open at the caret, innermost first. */
+function endTagCompletion(context: CompletionContext): CompletionResult | null {
+  const word = context.matchBefore(/\{%-?\s*\w*$/);
+  if (!word) return null;
+  const name = /\w*$/.exec(word.text)![0];
+  if (!name && !context.explicit) return null;
+  const from = word.to - name.length;
+  // Template syntax, not UI text.
+  const ends = openBlocks(context.state, from).map((block) => `end${block}`);
+  const options = ends.map((end, i) => ({ label: end, type: "keyword", boost: 99 - i }));
+  return options.length ? { from, options, validFor: /^\w*$/ } : null;
+}
+
+export function django(): LanguageSupport {
+  return new LanguageSupport(djangoLanguage, [
+    baseHTML.support,
+    // Markup is commented out with a template comment, which Django drops from the page.
+    baseHTML.language.data.of({ commentTokens: DJANGO_COMMENT, lineBoundComments: { multiline: COMMENT_TAG } }),
+    baseHTML.language.data.of({ djangoTemplate: true, autocomplete: endTagCompletion }),
+    djangoLanguage.data.of({
+      djangoTemplate: true,
+      autocomplete: endTagCompletion,
+      commentTokens: DJANGO_COMMENT,
+      lineBoundComments: { multiline: COMMENT_TAG },
+    }),
+    // A multi-line block comment, after `{# #}`, so that taking one out finds it.
+    Prec.lowest([
+      djangoLanguage.data.of({ commentTokens: { block: COMMENT_TAG } }),
+      baseHTML.language.data.of({ commentTokens: { block: COMMENT_TAG } }),
+    ]),
+    Prec.high([closePair, closeBlock]),
+  ]);
+}

src/editor/core/cm/django/parser.terms.ts

@@ -0,0 +1,45 @@
+// This file was generated by lezer-generator. You probably shouldn't edit it.
+export const
+  Comment = 1,
+  CommentBody = 2,
+  VerbatimBody = 3,
+  Text = 4,
+  OpenTagStart = 5,
+  CommentTagStart = 6,
+  VerbatimTagStart = 7,
+  MidTagStart = 8,
+  EndTagStart = 9,
+  TagStart = 10,
+  Template = 11,
+  Interpolation = 14,
+  VariableName = 15,
+  MemberExpression = 16,
+  PropertyName = 18,
+  Number = 19,
+  String = 20,
+  BooleanLiteral = 21,
+  None = 22,
+  FilterExpression = 23,
+  FilterOp = 24,
+  FilterName = 25,
+  Tag = 27,
+  TagName = 28,
+  _with = 29,
+  CompareOp = 30,
+  and = 33,
+  or = 34,
+  not = 35,
+  _in = 36,
+  is = 37,
+  as = 38,
+  only = 39,
+  from = 40,
+  TagEnd = 41,
+  Element = 42,
+  OpenTag = 43,
+  MidTag = 44,
+  EndTag = 45,
+  CommentElement = 46,
+  CommentTag = 47,
+  VerbatimElement = 48,
+  VerbatimTag = 49

src/editor/core/cm/django/parser.ts

@@ -0,0 +1,25 @@
+// This file was generated by lezer-generator. You probably shouldn't edit it.
+import {LRParser} from "@lezer/lr"
+import {comment, commentBody, verbatimBody, text, tagStart, blocks} from "./tokens"
+const spec_identifier = {__proto__:null,True:42, False:42, None:44, with:58, and:66, or:68, not:70, in:72, is:74, as:76, only:78, from:80}
+export const parser = LRParser.deserialize({
+  version: 14,
+  states: "+WQVO!ZOOO!PQpO'#CjO!WQpO'#CwO!WQpO'#DXO!`O!ZO'#DWO!WQpO'#D]O!jObO'#D[O!WQpO'#D_O!rOdO'#D^OOOi'#Df'#DfOOOi'#D`'#D`QVO!ZOOOOQO'#Ck'#CkO!zQpO'#DgO$[QpO,59UOOQO'#Dg'#DgOOOi,59U,59UOOQO'#Cx'#CxO$dQpO,59cO$dQpO,59sO!WQpO'#DYO%^O!ZO'#DbO%hO`O,59rO!WQpO'#DZOOOi,59r,59rO!`O!ZO,59rO$dQpO,59wOOOi,59v,59vO!mO`O,59vO$dQpO,59yOOOi,59x,59xO!mO`O,59xOOOi-E7^-E7^O%pQpO,59WOOQO'#Ct'#CtO%xQpO,59_OOOi1G.p1G.pO%}QpO'#DlOOQO'#C{'#C{OOQO'#Dl'#DlOOQO'#Da'#DaO$dQpO1G.}OOOo'#DV'#DVOOOi1G.}1G.}O$dQpO1G/_OOOi1G/_1G/_O$dQpO,59tO'XO!ZO,59|OOO`-E7`-E7`OOOi1G/^1G/^O$dQpO,59uO%hO`O1G/^O$dQpO1G/cOOOb1G/c1G/cOOOi1G/b1G/bO$dQpO1G/eOOOd1G/e1G/eOOOi1G/d1G/dOOQO'#Cn'#CnOOQO1G.r1G.rOOQO'#Cu'#CuO'cQpO1G.yOOQO-E7_-E7_OOOi7+$i7+$iOOOi7+$y7+$yO$dQpO1G/`OOOi1G/`1G/`O$dQpO1G/aOOOi1G/a1G/aOOOi7+$x7+$xOOOb7+$}7+$}OOOd7+%P7+%PO(sQpO7+$eOOOi7+$z7+$zOOOi7+${7+${O)OQpO'#DjOOQO'#Dj'#DjOOQO<<HP<<HP",
+  stateData: "*c~O!XOS~OPXOSXOTROUTOVVOYQO]PO~Oc_Od_Oe_Of_O![[O~O[`O~PnOmaO![aO~OWdOXgO~PVOQlOXgO~ORoOXgO~OaqO[!ZX!]!ZXc!ZXd!ZXe!ZXf!ZXm!ZXn!ZXp!ZXq!ZXr!ZXs!ZXt!ZXu!ZXv!ZXw!ZXx!ZX![!ZX!_!ZX~O[tO!]rO~OmwOnwOpvOqwOrwOswOtwOuwOvwOwwOxwO!_zO~PnOW!UXX!UX~PVOWdOXgO~Oc!]O![![O~O![!^O~O!]rOc!`Xd!`Xe!`Xf!`Xm!`Xn!`Xp!`Xq!`Xr!`Xs!`Xt!`Xu!`Xv!`Xw!`Xx!`X![!`X!_!`X~OW!UaX!Ua~PVOj!jO[gi!]gicgidgiegifgimgingipgiqgirgisgitgiugivgiwgixgi![gi!_gi~Oc!nOd!nO![[O~OaqO[!^X!]!^Xc!^Xd!^Xe!^Xf!^Xm!^Xn!^Xp!^Xq!^Xr!^Xs!^Xt!^Xu!^Xv!^Xw!^Xx!^X![!^X!_!^X~Onp~",
+  goto: "(T!aPPPPPPPPPPPPPP!b!j!jP!|PPPP#P#`#dP!b#gPP#yPPPPPPPPP$X!b$}%V%]!b%s!b%{&T&c&}PPP'X'aPP'rP'u]XOSZei!Pj]Pbcjmy|!O!S!U!X!c!eR!m!jR!]qk_Pbcjmy|!O!S!U!X!c!eTs^uR!_sQbQQcRQjTQmVQ!OdR!Sgiwbcjmy|!O!S!U!X!c!eQ{bQ}cQ!VjQ!YmQ!ayQ!b|Q!d!OQ!f!SQ!h!UQ!i!XQ!k!cR!l!e]SOSZei!PXeSfi!TQhSQkUQnWS!RfiQ!WlQ!ZoR!g!T]UOSZei!P]WOSZei!PQZOQiSUpZi!PR!PeQybQ|cQ!UjQ!Xm[!`y|!U!X!c!eQ!c!OR!e!SQfSS!Qf!TR!Ti]YOSZei!PQ^Piubcjmy|!O!S!U!X!c!eR!o!jixbcjmy|!O!S!U!X!c!e",
+  nodeNames: "⚠ Comment CommentBody VerbatimBody Text OpenTagStart CommentTagStart VerbatimTagStart MidTagStart EndTagStart TagStart Template }} {{ Interpolation VariableName MemberExpression . PropertyName Number String BooleanLiteral None FilterExpression FilterOp FilterName : Tag TagName with CompareOp AssignOp = and or not in is as only from TagEnd Element OpenTag MidTag EndTag CommentElement CommentTag VerbatimElement VerbatimTag",
+  maxTerm: 62,
+  context: blocks,
+  nodeProps: [
+    ["openedBy", 12,"{{"],
+    ["closedBy", 13,"}}"],
+    ["group", -7,15,16,19,20,21,22,23,"Expression"]
+  ],
+  skippedNodes: [0],
+  repeatNodeCount: 3,
+  tokenData: ")]~RhXY!mYZ!m]^!mpq!mqr#Ors#Zuv${wx%W}!O&s!O!P'd!Q![&y![!]'i!^!_'n!_!`'v!`!a'n!c!}(O#R#S(O#T#o(O#o#p(p#p#q({#q#r)Q$g;'S(O;'S;=`(j<%lO(O~!rS!X~XY!mYZ!m]^!mpq!m~#RP!_!`#U~#ZOn~~#`Vd~Or#Zrs#us#O#Z#O#P#z#P;'S#Z;'S;=`$u<%lO#Z~#zOd~~#}RO;'S#Z;'S;=`$W;=`O#Z~$]Wd~Or#Zrs#us#O#Z#O#P#z#P;'S#Z;'S;=`$u;=`<%l#Z<%lO#Z~$xP;=`<%l#Z~%OP#q#r%R~%WO!_~~%]Vd~Ow%Wwx#ux#O%W#O#P%r#P;'S%W;'S;=`&m<%lO%W~%uRO;'S%W;'S;=`&O;=`O%W~&TWd~Ow%Wwx#ux#O%W#O#P%r#P;'S%W;'S;=`&m;=`<%l%W<%lO%W~&pP;=`<%l%W~&vP!Q![&y~'OQc~!O!P'U!Q![&y~'XP!Q!['[~'aPc~!Q!['[~'iOa~~'nOj~~'sPn~!_!`#U~'{Pp~!_!`#U~(TV![~!Q![(O!c!}(O#R#S(O#T#o(O$g;'S(O;'S;=`(j<%lO(O~(mP;=`<%l(O~(sP#o#p(v~({O]~~)QO!]~~)TP#q#r)W~)]O[~",
+  tokenizers: [comment, commentBody, verbatimBody, text, tagStart, 0],
+  topRules: {"Template":[0,11]},
+  specialized: [{term: 58, get: (value: keyof typeof spec_identifier) => spec_identifier[value] || -1}],
+  tokenPrec: 430
+})

src/editor/core/cm/django/tokens.ts

@@ -0,0 +1,152 @@
+/**
+ * External tokens of `django.grammar`: the text between template elements, the
+ * comments, the raw content of `comment` and `verbatim`, and the start of each
+ * tag, classified by its name against the blocks open around it.
+ */
+import { ContextTracker, ExternalTokenizer, type InputStream, type Stack } from "@lezer/lr";
+import {
+  Comment,
+  CommentBody,
+  CommentElement,
+  CommentTagStart,
+  Element,
+  EndTagStart,
+  MidTagStart,
+  OpenTagStart,
+  TagStart,
+  Text,
+  VerbatimBody,
+  VerbatimElement,
+  VerbatimTagStart,
+} from "./parser.terms";
+
+const BRACE_L = 123,
+  BRACE_R = 125,
+  HASH = 35,
+  PERCENT = 37;
+
+/**
+ * Block tags of Django and its contrib libraries (`i18n`, `l10n`, `tz`, `cache`), with the
+ * middle tags each one allows.
+ */
+export const BLOCK_TAGS: ReadonlyMap<string, readonly string[]> = new Map([
+  ["autoescape", []],
+  ["block", []],
+  ["blocktrans", ["plural"]],
+  ["blocktranslate", ["plural"]],
+  ["cache", []],
+  ["comment", []],
+  ["filter", []],
+  ["for", ["empty"]],
+  ["if", ["elif", "else"]],
+  ["ifchanged", ["else"]],
+  ["language", []],
+  ["localize", []],
+  ["localtime", []],
+  ["partialdef", []],
+  ["spaceless", []],
+  ["timezone", []],
+  ["verbatim", []],
+  ["with", []],
+]);
+
+/** The block tags open around a position, innermost first. */
+class Block {
+  readonly hash: number;
+  constructor(
+    readonly name: string,
+    readonly parent: Block | null,
+  ) {
+    let hash = parent ? parent.hash : 0;
+    for (let i = 0; i < name.length; i++) hash = ((hash << 5) - hash + name.charCodeAt(i)) | 0;
+    this.hash = hash;
+  }
+}
+
+const isNameStart = (ch: number) => (ch >= 65 && ch <= 90) || (ch >= 97 && ch <= 122) || ch == 95;
+const isName = (ch: number) => isNameStart(ch) || (ch >= 48 && ch <= 57);
+const isSpace = (ch: number) => ch == 32 || ch == 9 || ch == 10 || ch == 13;
+
+/** The name of a tag whose `{%` is `offset` code units ahead. */
+function tagName(input: InputStream, offset = 0): string {
+  let i = offset + 2;
+  while (isSpace(input.peek(i))) i++;
+  let name = "";
+  for (let ch; isName((ch = input.peek(i))); i++) {
+    if (!name && !isNameStart(ch)) break;
+    name += String.fromCharCode(ch);
+  }
+  return name;
+}
+
+const tagAt = (input: InputStream, offset = 0) => input.peek(offset) == BRACE_L && input.peek(offset + 1) == PERCENT;
+
+/** Whether `{{`, `{%` or `{#` starts `offset` code units ahead. */
+function elementStart(input: InputStream, offset = 0): boolean {
+  if (input.peek(offset) != BRACE_L) return false;
+  const next = input.peek(offset + 1);
+  return next == BRACE_L || next == PERCENT || next == HASH;
+}
+
+export const blocks = new ContextTracker<Block | null>({
+  start: null,
+  shift(context, term, _stack, input) {
+    return term == OpenTagStart || term == CommentTagStart || term == VerbatimTagStart
+      ? new Block(tagName(input), context)
+      : context;
+  },
+  reduce(context, term) {
+    return (term == Element || term == CommentElement || term == VerbatimElement) && context ? context.parent : context;
+  },
+  hash: (context) => (context ? context.hash : 0),
+  strict: false,
+});
+
+/** `{# … #}`, to the end of the line when unterminated (it can't span lines). */
+export const comment = new ExternalTokenizer((input) => {
+  if (input.next != BRACE_L || input.peek(1) != HASH) return;
+  input.advance(2);
+  for (let ch; (ch = input.peek(0)) >= 0 && ch != 10;) {
+    if (ch == HASH && input.peek(1) == BRACE_R) {
+      input.advance(2);
+      break;
+    }
+    input.advance();
+  }
+  input.acceptToken(Comment);
+});
+
+/** Template text: up to a tag, a variable or a comment. */
+export const text = new ExternalTokenizer((input) => {
+  const start = input.pos;
+  while (input.next >= 0 && !elementStart(input)) input.advance();
+  if (input.pos > start) input.acceptToken(Text);
+});
+
+/** The `{%` of a tag, a token telling what the tag is in the blocks open around it. */
+export const tagStart = new ExternalTokenizer((input, stack: Stack) => {
+  if (!tagAt(input)) return;
+  const name = tagName(input);
+  const open: Block | null = stack.context;
+  let term = TagStart;
+  if (name == "comment") term = CommentTagStart;
+  else if (name == "verbatim") term = VerbatimTagStart;
+  else if (BLOCK_TAGS.has(name)) term = OpenTagStart;
+  else if (open && name == `end${open.name}`) term = EndTagStart;
+  else if (open && BLOCK_TAGS.get(open.name)?.includes(name)) term = MidTagStart;
+  if (!stack.canShift(term)) term = TagStart;
+  if (stack.canShift(term)) input.acceptToken(term, 2);
+});
+
+/** The content of a raw block: up to the `{% end<name>` closing it. */
+function rawBody(name: string, token: number) {
+  const end = `end${name}`;
+  return new ExternalTokenizer((input) => {
+    const start = input.pos;
+    while (input.next >= 0 && !(tagAt(input) && tagName(input) == end)) input.advance();
+    if (input.pos > start) input.acceptToken(token);
+  });
+}
+
+export const commentBody = rawBody("comment", CommentBody);
+export const verbatimBody = rawBody("verbatim", VerbatimBody);

src/editor/core/cm/gomod.test.ts

@@ -33,6 +33,21 @@ describe("goModParser", () => {
     ]);
   });
 
+  it("highlights tool, godebug and ignore directives", () => {
+    const state = initialGoModState();
+    expect(tokenize("tool golang.org/x/tools/cmd/stringer", state)).toEqual([
+      { text: "tool", token: "keyword" },
+      { text: "golang.org/x/tools/cmd/stringer", token: "string" },
+    ]);
+    expect(tokenize("tool (", state)[0]).toEqual({ text: "tool", token: "keyword" });
+    expect(tokenize("\tgithub.com/air-verse/air", state)).toEqual([
+      { text: "github.com/air-verse/air", token: "string" },
+    ]);
+    tokenize(")", state);
+    expect(tokenize("godebug default=go1.21", state)[0]).toEqual({ text: "godebug", token: "keyword" });
+    expect(tokenize("ignore ./node_modules", state)[0]).toEqual({ text: "ignore", token: "keyword" });
+  });
+
   it("highlights require blocks with module paths and versions", () => {
     const state = initialGoModState();
 

src/editor/core/cm/gomod.ts

@@ -1,6 +1,19 @@
 import { StreamLanguage, type StreamParser } from "@codemirror/language";
 
-const KEYWORDS = new Set(["module", "go", "toolchain", "require", "replace", "exclude", "retract", "use"]);
+/** go.mod and go.work directives (`tool` since Go 1.24, `ignore` since Go 1.25). */
+const KEYWORDS = new Set([
+  "module",
+  "go",
+  "toolchain",
+  "godebug",
+  "require",
+  "replace",
+  "exclude",
+  "retract",
+  "tool",
+  "ignore",
+  "use",
+]);
 
 export interface GoModState {
   currentKeyword: string | null;

src/editor/core/cm/languages.ts

@@ -131,6 +131,12 @@ const OWN_MODES = [
     load: () => import("./erb").then((m) => m.erb()),
   }),
   LanguageDescription.of({ name: "JSP", load: () => import("./jsp").then((m) => m.jsp()) }),
+  LanguageDescription.of({
+    name: "Django Template",
+    alias: ["django-html", "djhtml"],
+    extensions: ["djhtml"],
+    load: () => import("./django").then((m) => m.django()),
+  }),
   LanguageDescription.of({
     name: "Astro",
     extensions: ["astro"],

src/editor/core/customDocuments.test.ts

@@ -148,6 +148,9 @@ describe("custom editor document lifetime", () => {
         title: "Class",
         description: null,
         decompiled: true,
+        encoding: "utf-8",
+        hasBom: false,
+        canReloadEncoding: false,
       });
       await rejected;
       expect(findTab(useTabs.getState(), "virtual:jdt://old/Class")).toBeNull();

src/editor/core/model/document.ts

@@ -86,6 +86,8 @@ export interface DocMeta {
   lineEnding: LineEnding;
   readOnly: boolean;
   dirty: boolean;
+  /** "Reload with Encoding" can re-decode this document's source bytes. */
+  canReloadEncoding: boolean;
   banner: Banner;
   indent: { tabSize: number; insertSpaces: boolean };
 }
@@ -254,6 +256,7 @@ export class DocModel {
       // Library sources (External Libraries) open read-only, like IDEA's.
       readOnly: info.readOnly || (!this.virtual && isLibraryPath(info.path)),
       dirty: info.dirty,
+      canReloadEncoding: info.canReloadEncoding,
       banner: bannerFor(info),
       indent: { tabSize: 4, insertSpaces: true },
     };

src/editor/core/sync/DocSync.test.ts

@@ -28,6 +28,8 @@ class FakeServer {
   edits: Array<{ base: number; changes: TextChange[] }> = [];
   private queue: Array<() => void> = [];
   snapshots = 0;
+  /** Snapshots still to reject (a transient IPC or remote-host failure). */
+  failSnapshots = 0;
   failNext: unknown = null;
   constructor(public text: string) {}
 
@@ -52,6 +54,10 @@ class FakeServer {
       }),
     snapshot: async () => {
       this.snapshots++;
+      if (this.failSnapshots > 0) {
+        this.failSnapshots--;
+        throw { kind: "unavailable", message: "snapshot failed" };
+      }
       return { text: this.text, version: this.version };
     },
   };
@@ -218,6 +224,76 @@ describe("DocSync", () => {
     }
   });
 
+  it("keeps syncing when the snapshot of a rebase fails once", async () => {
+    vi.useFakeTimers();
+    try {
+      const { server, view, sync, type, frame, host } = setup("one\ntwo\n");
+      type(8, 8, "three\n");
+      frame();
+      server.patch([{ from: 0, to: 3, insert: "ONE" }]); // event lost
+      server.failSnapshots = 1;
+      let idle = false;
+      void sync.whenIdle().then(() => (idle = true));
+      for (let i = 0; i < 4; i++) {
+        await server.processAll();
+        await vi.advanceTimersByTimeAsync(100);
+      }
+      expect(server.snapshots).toBe(2);
+      expect(host.onError).toHaveBeenCalledWith(expect.objectContaining({ kind: "unavailable" }));
+      expect(server.text).toBe("ONE\ntwo\nthree\n");
+      expect(view.text.toString()).toBe(server.text);
+      expect(sync.idle).toBe(true);
+      expect(idle).toBe(true);
+      expect(host.onDiscarded).not.toHaveBeenCalled();
+
+      // Later typing still reaches the backend.
+      type(0, 0, "#");
+      frame();
+      await server.processAll();
+      expect(server.text).toBe("#ONE\ntwo\nthree\n");
+      expect(sync.idle).toBe(true);
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
+  it("stops retrying when every snapshot fails, and keeps the local text to send later", async () => {
+    vi.useFakeTimers();
+    try {
+      const { server, view, sync, type, frame, host } = setup("one\ntwo\n");
+      type(8, 8, "three\n");
+      frame();
+      server.patch([{ from: 0, to: 3, insert: "ONE" }]); // event lost
+      server.failSnapshots = Infinity;
+      let idle = false;
+      void sync.whenIdle().then(() => (idle = true));
+      for (let i = 0; i < 20 && !idle; i++) {
+        await server.processAll();
+        await vi.advanceTimersByTimeAsync(100);
+      }
+      // A save waiting on the document is released instead of hanging, and nothing is in flight.
+      expect(idle).toBe(true);
+      expect(sync.inflight).toBeNull();
+      expect(server.pending()).toBe(0);
+      expect(host.onError).toHaveBeenCalled();
+      expect(view.text.toString()).toBe("one\ntwo\nthree\n");
+
+      // Once the backend answers again, the local text and new typing land where they belong.
+      server.failSnapshots = 0;
+      type(0, 0, "#");
+      frame();
+      for (let i = 0; i < 4; i++) {
+        await server.processAll();
+        await vi.advanceTimersByTimeAsync(100);
+      }
+      expect(server.text).toBe("#ONE\ntwo\nthree\n");
+      expect(view.text.toString()).toBe(server.text);
+      expect(sync.idle).toBe(true);
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+
   it("hard-resyncs on unexpected errors and reports discarded changes", async () => {
     const { server, view, sync, type, frame, host } = setup("abc");
     server.failNext = { kind: "permissionDenied", message: "read-only" };

src/editor/core/sync/DocSync.ts

@@ -251,9 +251,11 @@ export class DocSync {
     try {
       snap = await this.transport.snapshot();
     } catch (e) {
+      if (gen !== this.generation || this.disposed) return;
       this.host.onError?.(e);
-      this.resyncing = false;
-      this.resolveIdle(true);
+      // Keep the edit going: the backend acks it once it caught up, or rejects it again,
+      // which retries the snapshot (a hard resync after MAX_REBASES).
+      this.resend();
       return;
     }
     if (gen !== this.generation || this.disposed) return;
@@ -313,8 +315,13 @@ export class DocSync {
     } catch (e) {
       if (gen !== this.generation) return;
       this.host.onError?.(e);
+      // Nothing to adopt: keep the local text as pending changes against `confirmed`, so the
+      // next flush sends them in the coordinates the backend knows.
+      const pending = minimalChanges(this.confirmed.toString(), this.localText.toString());
       this.inflight = null;
-      this.buffer = null;
+      this.buffer = pending.length ? ChangeSet.of(pending, this.confirmed.length) : null;
+      this.inflightStale = false;
+      this.rebases = 0;
       this.resyncing = false;
       this.resolveIdle(true);
       return;