fix(editor): clicking the author hint again closes the blame annotations (#3448)

The Code Vision author hint ran Annotate with Git Blame only while the annotations were hidden, so a second click left them open. It now runs vcs.annotate on every click, toggling the annotations like the action itself.

Cargo.lock

@@ -4269,6 +4269,7 @@ dependencies = [
 name = "ide-dap"
 version = "0.1.45"
 dependencies = [
+ "base64 0.22.1",
  "futures",
  "ide-core",
  "ide-heap",
@@ -4287,6 +4288,7 @@ dependencies = [
  "specta",
  "tempfile",
  "tokio",
+ "tokio-tungstenite",
  "tracing",
  "tracing-subscriber",
  "windows-sys 0.61.2",

crates/ide-build/src/compile/mod.rs

@@ -53,6 +53,8 @@ pub enum BuildSystem {
     TypeScript,
     #[serde(rename = "cmake")]
     CMake,
+    #[serde(rename = "dotnet")]
+    Dotnet,
 }
 
 /// One command of a build.
@@ -165,6 +167,8 @@ fn detect_dir(dir: &Path, model: &BuildModel, root: &Path) -> Option<BuildSystem
         || has(dir, &["build.gradle", "build.gradle.kts", "settings.gradle", "settings.gradle.kts"])
     {
         Some(BuildSystem::Gradle)
+    } else if dotnet_target(dir).is_some() {
+        Some(BuildSystem::Dotnet)
     } else if has(dir, &["Cargo.toml"]) {
         Some(BuildSystem::Cargo)
     } else if has(dir, &["go.mod", "go.work"]) {
@@ -225,7 +229,7 @@ pub fn plan(
         .or((!model.gradle.is_empty()).then_some(BuildSystem::Gradle))
         .or_else(|| model.maven.as_ref().filter(|m| !m.projects.is_empty()).map(|_| BuildSystem::Maven))
         .ok_or_else(|| {
-            IdeError::not_found("no supported build system (Maven, Gradle, Cargo, Go, TypeScript, CMake) found")
+            IdeError::not_found("no supported build system (Maven, Gradle, .NET, Cargo, Go, TypeScript, CMake) found")
         })?;
     let module = module_dir.as_deref().filter(|d| *d != root);
     let title = match module {
@@ -244,6 +248,7 @@ pub fn plan(
         BuildSystem::Go => go_steps(file.and_then(Path::parent).unwrap_or(&dir), kind)?,
         BuildSystem::TypeScript => ts_steps(&dir, kind),
         BuildSystem::CMake => cmake_steps(&dir, kind, cmake.and_then(<[_]>::first)),
+        BuildSystem::Dotnet => dotnet_steps(&dir, kind)?,
     };
     Ok(BuildPlan { system, title, steps })
 }
@@ -451,6 +456,33 @@ fn has_build_script(dir: &Path) -> bool {
         .is_some_and(|v| v.pointer("/scripts/build").is_some_and(serde_json::Value::is_string))
 }
 
+/// The solution (`.sln` / `.slnx`) or project (`.csproj` / `.fsproj` / `.vbproj`) file `dir`
+/// builds: a solution first, then a project; the first by name when there are several.
+fn dotnet_target(dir: &Path) -> Option<PathBuf> {
+    let mut files: Vec<PathBuf> =
+        std::fs::read_dir(dir).ok()?.flatten().map(|e| e.path()).filter(|p| p.is_file()).collect();
+    files.sort();
+    let ext = |p: &Path| p.extension().map(|e| e.to_string_lossy().to_ascii_lowercase()).unwrap_or_default();
+    let solution = files.iter().find(|p| matches!(ext(p).as_str(), "sln" | "slnx"));
+    solution.or_else(|| files.iter().find(|p| matches!(ext(p).as_str(), "csproj" | "fsproj" | "vbproj"))).cloned()
+}
+
+/// `dotnet build` of the directory's solution or project; Rebuild skips incremental builds,
+/// Build Artifacts publishes. The summary that repeats every message is left out.
+fn dotnet_steps(dir: &Path, kind: BuildKind) -> IdeResult<Vec<BuildStep>> {
+    let target = dotnet_target(dir).ok_or_else(|| IdeError::not_found("no .NET solution or project found"))?;
+    let target = target.file_name().map_or_else(String::new, |n| n.to_string_lossy().into_owned());
+    let verb = if kind == BuildKind::Artifacts { "publish" } else { "build" };
+    let mut step = BuildStep::new("dotnet", &[verb, &target, "-nologo", "-clp:NoSummary"], dir, Format::Msbuild);
+    if kind == BuildKind::Rebuild {
+        step.args.push("--no-incremental".into());
+    }
+    // The classic console logger prints the canonical `file(line,col): error` lines; the
+    // terminal logger (.NET 8+) only appears on a terminal, but rules it out for older SDKs too.
+    step.env.insert("MSBUILDTERMINALLOGGER".into(), "off".into());
+    Ok(vec![step])
+}
+
 fn ts_steps(dir: &Path, kind: BuildKind) -> Vec<BuildStep> {
     let script = has_build_script(dir);
     if script && (kind == BuildKind::Artifacts || !dir.join("tsconfig.json").is_file()) {
@@ -1141,6 +1173,24 @@ mod tests {
             ("pnpm", &["run".to_owned(), "build".to_owned()][..])
         );
 
+        // .NET: the solution, else the project; a module build is the file's project. An ASP.NET
+        // project's package.json (its front end) doesn't make it a TypeScript build.
+        let net = tmp.path().join("net");
+        write(&net, "App.sln", "");
+        write(&net, "src/Api/Api.csproj", "<Project/>");
+        write(&net, "src/Api/package.json", "{}");
+        write(&net, "src/Api/Program.cs", "");
+        let p = plan(&net, &BuildModel::default(), BuildKind::Build, None, None).unwrap();
+        assert_eq!(p.system, BuildSystem::Dotnet);
+        assert_eq!(p.steps[0].args, ["build", "App.sln", "-nologo", "-clp:NoSummary"]);
+        assert_eq!(p.steps[0].env["MSBUILDTERMINALLOGGER"], "off");
+        let p = plan(&net, &BuildModel::default(), BuildKind::Rebuild, Some(&net.join("src/Api/Program.cs")), None)
+            .unwrap();
+        assert_eq!(p.steps[0].args, ["build", "Api.csproj", "-nologo", "-clp:NoSummary", "--no-incremental"]);
+        assert_eq!(p.steps[0].cwd, net.join("src/Api"));
+        let p = plan(&net, &BuildModel::default(), BuildKind::Artifacts, None, None).unwrap();
+        assert_eq!(p.steps[0].args[0], "publish");
+
         let cm = tmp.path().join("cm");
         write(&cm, "CMakeLists.txt", "project(app)");
         let args = |p: &BuildPlan| p.steps.iter().map(|s| s.args.join(" ")).collect::<Vec<_>>();

crates/ide-build/src/compile/parse.rs

@@ -25,6 +25,8 @@ pub(crate) enum Format {
     Go,
     /// GCC / Clang (through `cmake --build`): `src/a.cpp:12:5: error: msg`.
     Gcc,
+    /// MSBuild (`dotnet build`): `C:\p\A.cs(12,5): error CS1002: msg [C:\p\App.csproj]`.
+    Msbuild,
 }
 
 /// What a printed column counts.
@@ -268,6 +270,43 @@ fn tsc_line(line: &str) -> Option<RawMessage> {
     Some(m)
 }
 
+/// MSBuild's canonical form: `path(12,5): error CS1002: msg [project]`, `path(12,5,12,9): …`,
+/// or `path : error NU1101: msg [project]` for a project-level message (no position).
+/// The path may contain spaces (`C:\Users\Jane Doe\…`); "error" / "warning" are never localized.
+fn msbuild_line(line: &str) -> Option<RawMessage> {
+    let line = line.trim();
+    // The project the message came from, appended by the console logger.
+    let line = match line.rfind(" [") {
+        Some(i) if line.ends_with(']') => &line[..i],
+        _ => line,
+    };
+    let (head, severity, rest) =
+        [(" error ", Severity::Error), (" warning ", Severity::Warning)].into_iter().find_map(|(word, severity)| {
+            let i = line.find(&format!(":{word}"))?;
+            Some((&line[..i], severity, &line[i + word.len() + 1..]))
+        })?;
+    let (code, msg) = rest.split_once(':')?;
+    let code = code.trim();
+    if code.is_empty() || code.contains(' ') {
+        return None;
+    }
+    let head = head.trim_end();
+    let (path, pos) = match head.strip_suffix(')').and_then(|h| h.rsplit_once('(')) {
+        Some((path, pos)) => (path, pos.split(',').map(num).collect::<Vec<_>>()),
+        None => (head, Vec::new()),
+    };
+    let at = |i: usize| pos.get(i).copied().flatten();
+    // `MSBUILD : error MSB1009` and the like name no file.
+    let file = path.rsplit(['/', '\\']).next().is_some_and(|n| n.contains('.'));
+    let mut m = RawMessage::new(severity, msg.trim(), ColUnit::Utf16);
+    if file {
+        m.path = Some(path.trim().to_owned());
+        (m.line, m.col, m.end_line, m.end_col) = (at(0), at(1), at(2), at(3));
+    }
+    m.code = Some(code.to_owned());
+    Some(m)
+}
+
 /// go: `./a.go:12:5: msg` (errors only; `go vet` style `a.go:12: msg` too).
 fn go_line(line: &str) -> Option<RawMessage> {
     let (path, ln, col, rest) = path_line_col(line)?;
@@ -404,6 +443,7 @@ impl OutputParser {
             Format::Tsc => tsc_line(&line),
             Format::Go => go_line(&line),
             Format::Gcc => gcc_line(&line),
+            Format::Msbuild => msbuild_line(&line),
             Format::Cargo => None,
         };
         if let Some(msg) = parsed {
@@ -551,6 +591,27 @@ mod tests {
         assert!(plain.messages.is_empty() && plain.console.is_none());
     }
 
+    #[test]
+    fn msbuild_canonical_messages() {
+        let out = parse(
+            Format::Msbuild,
+            "  Determining projects to restore...\n\
+             C:\\Users\\Jane Doe\\App\\Program.cs(12,5): error CS1002: ; expected [C:\\Users\\Jane Doe\\App\\App.csproj]\n\
+             /p/App/Models/User.cs(3,8,3,12): warning CS0168: The variable 'e' is declared but never used [/p/App/App.csproj]\n\
+             /p/App/App.csproj : error NU1101: Unable to find package Foo. [/p/App/App.csproj]\n\
+             MSBUILD : error MSB1009: Project file does not exist.\n\
+             Build FAILED.\n",
+        );
+        assert_eq!(out.len(), 4, "{out:?}");
+        assert_eq!(pos(&out[0]), (Severity::Error, "C:\\Users\\Jane Doe\\App\\Program.cs", 12, Some(5)));
+        assert_eq!((out[0].code.as_deref(), out[0].text.as_str()), (Some("CS1002"), "; expected"));
+        assert_eq!(pos(&out[1]), (Severity::Warning, "/p/App/Models/User.cs", 3, Some(8)));
+        assert_eq!((out[1].end_line, out[1].end_col), (Some(3), Some(12)));
+        assert_eq!((out[2].path.as_deref(), out[2].line), (Some("/p/App/App.csproj"), None));
+        assert_eq!(out[2].text, "Unable to find package Foo.");
+        assert_eq!((out[3].path.as_deref(), out[3].code.as_deref()), (None, Some("MSB1009")));
+    }
+
     #[test]
     fn tsc_plain_and_pretty() {
         let out = parse(

crates/ide-core/src/event.rs

@@ -118,6 +118,10 @@ pub enum IdeEvent {
     LanguageServer {
         server: ServerId,
         name: String,
+        /// What the user sees as the server when another program serves in its place.
+        #[serde(default)]
+        #[specta(optional)]
+        label: Option<String>,
         status: ServerStatus,
         message: Option<String>,
     },

crates/ide-core/src/jsonc.rs

@@ -1,8 +1,10 @@
 //! JSON with comments (`devcontainer.json`, `deno.jsonc`, `tsconfig.json`): turned
 //! into plain JSON for `serde_json`.
 
-/// Strips `//` and `/* */` comments and trailing commas so JSONC parses as JSON.
+/// Strips `//` and `/* */` comments, trailing commas and a leading byte order mark (Visual
+/// Studio writes one into `launchSettings.json`) so JSONC parses as JSON.
 pub fn strip(src: &str) -> String {
+    let src = src.strip_prefix('\u{feff}').unwrap_or(src);
     let mut out = String::with_capacity(src.len());
     let mut chars = src.chars().peekable();
     let mut in_str = false;
@@ -87,4 +89,10 @@ mod tests {
         assert_eq!(v["url"], "https://x.dev//y /* no */");
         assert_eq!(v["q"], "say \"hi\",");
     }
+
+    #[test]
+    fn drops_a_byte_order_mark() {
+        let v: serde_json::Value = serde_json::from_str(&strip("\u{feff}{ \"a\": 1 }")).unwrap();
+        assert_eq!(v["a"], 1);
+    }
 }

crates/ide-core/src/settings.rs

@@ -1092,7 +1092,8 @@ impl Default for ExternalFormatterSettings {
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize, Type)]
 #[serde(default, rename_all = "camelCase")]
 pub struct PythonSettings {
-    /// Project interpreter executable; empty = auto-detect (project venv, else `python3`).
+    /// Project interpreter executable; empty = auto-detect (project venv, else `python3`);
+    /// `target:<run-target-id>` = the Python of a Docker or Compose run target.
     pub interpreter: String,
     /// Activate the interpreter's virtualenv in new terminal sessions.
     pub activate_virtualenv: bool,
@@ -1121,6 +1122,17 @@ impl Default for PythonSettings {
     }
 }
 
+impl PythonSettings {
+    /// What `interpreter` starts with when the project interpreter is a run target's.
+    pub const TARGET_PREFIX: &str = "target:";
+
+    /// The run target whose Python is the project interpreter (`target:<id>`), if one is.
+    pub fn run_target(&self) -> Option<&str> {
+        let id = self.interpreter.trim().strip_prefix(Self::TARGET_PREFIX)?.trim();
+        (!id.is_empty()).then_some(id)
+    }
+}
+
 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Type)]
 #[serde(default, rename_all = "camelCase")]
 pub struct PhpSettings {
@@ -1542,6 +1554,16 @@ impl Settings {
 mod tests {
     use super::*;
 
+    #[test]
+    fn python_interpreter_may_name_a_run_target() {
+        let python = |interpreter: &str| PythonSettings { interpreter: interpreter.into(), ..Default::default() };
+        assert_eq!(python("target:web").run_target(), Some("web"));
+        assert_eq!(python(" target: web ").run_target(), Some("web"));
+        for local in ["", "target:", "/usr/bin/python3", ".venv/bin/python", "targets/python"] {
+            assert_eq!(python(local).run_target(), None, "{local}");
+        }
+    }
+
     #[test]
     fn removed_one_themes_read_as_islands_themes() {
         let settings: Settings = serde_json::from_str(

crates/ide-dap/Cargo.toml

@@ -7,6 +7,8 @@ license.workspace = true
 
 [dependencies]
 futures.workspace = true
+tokio-tungstenite.workspace = true
+base64.workspace = true
 tempfile.workspace = true
 ide-core.workspace = true
 ide-language.workspace = true

crates/ide-dap/src/js_cdp.rs

@@ -0,0 +1,528 @@
+//! Replacing the responses a debugged page receives. js-debug hands out a WebSocket that
+//! speaks the browser's own protocol (`requestCDPProxy`); over it the browser is told to hold
+//! the requests whose URL matches a rule (`Fetch.enable`) and each held request is answered
+//! here, with the rule's response or by letting it through.
+//!
+//! A held request stays held until it is answered, so interception is always switched off
+//! (`Fetch.disable`) before the connection is given up: a page whose requests nobody answers hangs.
+
+use crate::{DebugManager, DebugSessionId, REQUEST_TIMEOUT, js_debug};
+use base64::Engine;
+use futures::{SinkExt, StreamExt};
+use ide_core::{IdeError, IdeResult};
+use serde::{Deserialize, Serialize};
+use serde_json::{Value, json};
+use specta::Type;
+use std::collections::HashMap;
+use tokio::sync::{oneshot, watch};
+use tokio_tungstenite::tungstenite::{Message, http::StatusCode};
+
+/// A response given in place of the server's to every request whose URL contains `url_contains`.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct JsResponseRule {
+    pub url_contains: String,
+    pub status: u16,
+    pub content_type: String,
+    pub body: String,
+}
+
+/// The browser's URL pattern (`*` any text, `?` one character, `\` escapes) for "contains `part`".
+pub(crate) fn url_pattern(part: &str) -> String {
+    let mut pattern = String::with_capacity(part.len() + 2);
+    pattern.push('*');
+    for c in part.chars() {
+        if matches!(c, '*' | '?' | '\\') {
+            pattern.push('\\');
+        }
+        pattern.push(c);
+    }
+    pattern.push('*');
+    pattern
+}
+
+pub(crate) fn rule_for<'a>(rules: &'a [JsResponseRule], url: &str) -> Option<&'a JsResponseRule> {
+    rules.iter().find(|rule| url.contains(&rule.url_contains))
+}
+
+/// What to tell the browser about a request it holds: the first matching rule's response, or
+/// to send the request on. Every held request gets one of the two.
+pub(crate) fn answer(held: &Value, rules: &[JsResponseRule]) -> (&'static str, Value) {
+    let request_id = held.get("requestId").and_then(Value::as_str).unwrap_or_default();
+    let url = held.pointer("/request/url").and_then(Value::as_str).unwrap_or_default();
+    let Some(rule) = rule_for(rules, url) else {
+        return ("Fetch.continueRequest", json!({ "requestId": request_id }));
+    };
+    let header = |name: &str, value: &str| json!({ "name": name, "value": value });
+    // A page on another origin only reads a response that names its origin. The server would
+    // say so; the response given in its place has to.
+    let mut cross_origin = Vec::new();
+    if let Some(origin) = request_header(held, "Origin") {
+        cross_origin.push(header("Access-Control-Allow-Origin", origin));
+        cross_origin.push(header("Access-Control-Allow-Credentials", "true"));
+    }
+    let method = held.pointer("/request/method").and_then(Value::as_str).unwrap_or_default();
+    // The browser's question before such a request: allowed here, the server may not exist.
+    if method == "OPTIONS"
+        && let Some(asked) = request_header(held, "Access-Control-Request-Method")
+    {
+        cross_origin.push(header("Access-Control-Allow-Methods", asked));
+        if let Some(asked) = request_header(held, "Access-Control-Request-Headers") {
+            cross_origin.push(header("Access-Control-Allow-Headers", asked));
+        }
+        let allowed = json!({
+            "requestId": request_id,
+            "responseCode": 204,
+            "responsePhrase": phrase(204),
+            "responseHeaders": cross_origin,
+        });
+        return ("Fetch.fulfillRequest", allowed);
+    }
+    let mut headers = vec![header("Content-Type", &rule.content_type)];
+    headers.extend(cross_origin);
+    let replaced = json!({
+        "requestId": request_id,
+        "responseCode": rule.status,
+        "responsePhrase": phrase(rule.status),
+        "responseHeaders": headers,
+        "body": base64::engine::general_purpose::STANDARD.encode(rule.body.as_bytes()),
+    });
+    ("Fetch.fulfillRequest", replaced)
+}
+
+/// A header of the held request; the browser reports names as the page wrote them.
+fn request_header<'a>(held: &'a Value, name: &str) -> Option<&'a str> {
+    held.pointer("/request/headers")?.as_object()?.iter().find(|(key, _)| key.eq_ignore_ascii_case(name))?.1.as_str()
+}
+
+/// The browser refuses a response without a phrase when it has none of its own for the status.
+fn phrase(status: u16) -> &'static str {
+    StatusCode::from_u16(status).ok().and_then(|status| status.canonical_reason()).unwrap_or("Unknown")
+}
+
+fn interception(rules: &[JsResponseRule]) -> Value {
+    let patterns: Vec<Value> = rules
+        .iter()
+        .map(|rule| json!({ "urlPattern": url_pattern(&rule.url_contains), "requestStage": "Request" }))
+        .collect();
+    json!({ "patterns": patterns })
+}
+
+/// Applies `rules` to the page behind js-debug's CDP proxy at `ws_url` until their sender is
+/// dropped (the session is gone) or the proxy closes the connection. The browser holds
+/// requests only while there are rules. `ready` hears whether the proxy reports held
+/// requests at all; nothing is held before it has agreed to.
+pub(crate) async fn serve(
+    ws_url: String,
+    mut rules: watch::Receiver<Vec<JsResponseRule>>,
+    ready: oneshot::Sender<Result<(), String>>,
+) {
+    let socket = match tokio_tungstenite::connect_async(ws_url.as_str()).await {
+        Ok((socket, _)) => socket,
+        Err(e) => {
+            let _ = ready.send(Err(e.to_string()));
+            return;
+        }
+    };
+    let (mut write, mut read) = socket.split();
+    let mut last_id = 0u64;
+    let mut call = |method: &str, params: Value| {
+        last_id += 1;
+        (last_id, Message::text(json!({ "id": last_id, "method": method, "params": params }).to_string()))
+    };
+
+    let (subscription, subscribe) = call("JsDebug.subscribe", json!({ "events": ["Fetch.requestPaused"] }));
+    let subscribed = tokio::time::timeout(REQUEST_TIMEOUT, async {
+        write.send(subscribe).await.map_err(|e| e.to_string())?;
+        loop {
+            let reply = read.next().await.ok_or("the connection closed")?.map_err(|e| e.to_string())?;
+            let Some(reply) = reply.to_text().ok().and_then(|text| serde_json::from_str::<Value>(text).ok()) else {
+                continue;
+            };
+            if reply.get("id").and_then(Value::as_u64) != Some(subscription) {
+                continue;
+            }
+            break match reply.get("error") {
+                Some(error) => Err(error.get("message").and_then(Value::as_str).unwrap_or("refused").to_owned()),
+                None => Ok(()),
+            };
+        }
+    })
+    .await
+    .unwrap_or_else(|_| Err("no answer".to_owned()));
+    if let Err(why) = subscribed {
+        let _ = ready.send(Err(why));
+        let _ = write.close().await;
+        return;
+    }
+    let _ = ready.send(Ok(()));
+
+    let mut current = rules.borrow_and_update().clone();
+    let mut holding = !current.is_empty();
+    if holding && write.send(call("Fetch.enable", interception(&current)).1).await.is_err() {
+        return;
+    }
+    // The request each sent replacement is for, by command id, until the browser has taken it.
+    let mut replacing: HashMap<u64, String> = HashMap::new();
+    loop {
+        tokio::select! {
+            changed = rules.changed() => {
+                if changed.is_err() {
+                    break;
+                }
+                current = rules.borrow_and_update().clone();
+                let (_, command) = match (current.is_empty(), holding) {
+                    (true, false) => continue,
+                    (true, true) => call("Fetch.disable", json!({})),
+                    (false, _) => call("Fetch.enable", interception(&current)),
+                };
+                holding = !current.is_empty();
+                if write.send(command).await.is_err() {
+                    return;
+                }
+            }
+            message = read.next() => {
+                // The proxy closed (the page or the session ended): nothing is held any more.
+                let Some(Ok(message)) = message else { return };
+                let Ok(text) = message.to_text() else { continue };
+                let Ok(message) = serde_json::from_str::<Value>(text) else { continue };
+                if let Some(id) = message.get("id").and_then(Value::as_u64) {
+                    // The browser did not take the replacement: let the request through, or
+                    // it stays held and the page waits for it.
+                    if let Some(request_id) = replacing.remove(&id)
+                        && message.get("error").is_some()
+                    {
+                        let (_, go_on) = call("Fetch.continueRequest", json!({ "requestId": request_id }));
+                        if write.send(go_on).await.is_err() {
+                            return;
+                        }
+                    }
+                    continue;
+                }
+                if message.get("method").and_then(Value::as_str) != Some("Fetch.requestPaused") {
+                    continue;
+                }
+                let Some(held) = message.get("params") else { continue };
+                let Some(request_id) = held.get("requestId").and_then(Value::as_str) else { continue };
+                let (method, params) = answer(held, &current);
+                let (id, command) = call(method, params);
+                if method == "Fetch.fulfillRequest" {
+                    replacing.insert(id, request_id.to_owned());
+                }
+                if write.send(command).await.is_err() {
+                    return;
+                }
+            }
+        }
+    }
+    if holding {
+        let _ = write.send(call("Fetch.disable", json!({})).1).await;
+    }
+    let _ = write.close().await;
+}
+
+impl DebugManager {
+    /// Makes `rules` the page's response rules; none switches the replacing off. The first
+    /// rules of a session open the connection to js-debug's CDP proxy, later ones go over it.
+    /// An error means the rules are not applied.
+    pub async fn js_set_response_overrides(&self, s: DebugSessionId, rules: Vec<JsResponseRule>) -> IdeResult<()> {
+        let session = self.session(s)?;
+        if !js_debug::is_page(&session) {
+            return Err(IdeError::unavailable("this debug session is not a page in a browser"));
+        }
+        // Held to the end: two callers at once would each open a connection.
+        let mut applied = session.js_overrides.lock().await;
+        if applied.as_ref().is_some_and(|sender| sender.send(rules.clone()).is_ok()) {
+            return Ok(());
+        }
+        // No connection yet, or the proxy closed it.
+        applied.take();
+        if rules.is_empty() {
+            return Ok(());
+        }
+        let refused =
+            |why: String| IdeError::unavailable(format!("the JavaScript debugger has no browser connection: {why}"));
+        if !js_debug::launched(&session).await {
+            return Err(refused("the page's debug session did not finish starting".into()));
+        }
+        let proxy = session
+            .conn
+            .request_timeout("requestCDPProxy", json!({}), REQUEST_TIMEOUT)
+            .await
+            .map_err(|e| refused(e.to_string()))?;
+        let (Some(host), Some(port)) =
+            (proxy.get("host").and_then(Value::as_str), proxy.get("port").and_then(Value::as_u64))
+        else {
+            return Err(refused("no address".into()));
+        };
+        let path = proxy.get("path").and_then(Value::as_str).unwrap_or_default();
+        let (sender, receiver) = watch::channel(rules);
+        let (ready, is_ready) = oneshot::channel();
+        tokio::spawn(serve(format!("ws://{host}:{port}{path}"), receiver, ready));
+        match is_ready.await {
+            Ok(Ok(())) => {
+                *applied = Some(sender);
+                Ok(())
+            }
+            Ok(Err(why)) => Err(refused(why)),
+            Err(_) => Err(refused("no answer".into())),
+        }
+    }
+}
+
+#[cfg(test)]
+pub(crate) mod tests {
+    use super::*;
+    use futures::{SinkExt, StreamExt};
+    use serde_json::json;
+    use tokio::sync::mpsc;
+    use tokio_tungstenite::tungstenite::Message;
+
+    pub(crate) fn rule(url_contains: &str, status: u16, body: &str) -> JsResponseRule {
+        JsResponseRule {
+            url_contains: url_contains.into(),
+            status,
+            content_type: "application/json".into(),
+            body: body.into(),
+        }
+    }
+
+    #[test]
+    fn a_part_of_a_url_becomes_a_pattern_that_matches_it_anywhere() {
+        assert_eq!(url_pattern("api/items"), "*api/items*");
+        // The pattern's own wildcards and escape character are taken literally.
+        assert_eq!(url_pattern(r"a*b?c\d"), r"*a\*b\?c\\d*");
+    }
+
+    #[test]
+    fn the_first_rule_whose_text_is_in_the_url_answers() {
+        let rules = [rule("api/items", 201, "{\"a\":\"é\"}"), rule("api", 500, "later")];
+        assert_eq!(rule_for(&rules, "http://h/api/items?x=1").map(|r| r.status), Some(201));
+        assert_eq!(rule_for(&rules, "http://h/api/users").map(|r| r.status), Some(500));
+        assert!(rule_for(&rules, "http://h/logo.png").is_none());
+
+        let (command, params) = answer(&held("7", "http://h/api/items")["params"], &rules);
+        assert_eq!(command, "Fetch.fulfillRequest");
+        assert_eq!(
+            params,
+            json!({
+                "requestId": "7",
+                "responseCode": 201,
+                "responsePhrase": "Created",
+                "responseHeaders": [{ "name": "Content-Type", "value": "application/json" }],
+                // base64 of the UTF-8 text `{"a":"é"}`
+                "body": "eyJhIjoiw6kifQ==",
+            })
+        );
+        // A request the browser held that no rule is for goes on to the network.
+        assert_eq!(
+            answer(&held("8", "http://h/logo.png")["params"], &rules),
+            ("Fetch.continueRequest", json!({ "requestId": "8" }))
+        );
+    }
+
+    #[test]
+    fn a_status_the_browser_has_no_phrase_for_is_given_one() {
+        // The browser refuses a response whose status it cannot name.
+        let (_, params) = answer(&held("1", "http://h/api")["params"], &[rule("api", 419, "")]);
+        assert_eq!((&params["responseCode"], &params["responsePhrase"]), (&json!(419), &json!("Unknown")));
+    }
+
+    fn header<'a>(params: &'a Value, name: &str) -> Option<&'a str> {
+        params["responseHeaders"].as_array()?.iter().find(|h| h["name"] == name)?["value"].as_str()
+    }
+
+    #[test]
+    fn a_replaced_response_passes_the_pages_cross_origin_check() {
+        let rules = [rule("api/items", 200, "[]")];
+        let from_page = |method: &str, headers: Value| json!({ "requestId": "3", "request": { "url": "http://localhost:8080/api/items", "method": method, "headers": headers } });
+        // A page on another origin: the response names that origin, as the real server would.
+        let (_, params) = answer(&from_page("GET", json!({ "origin": "http://localhost:5173" })), &rules);
+        assert_eq!(header(&params, "Access-Control-Allow-Origin"), Some("http://localhost:5173"));
+        assert_eq!(header(&params, "Access-Control-Allow-Credentials"), Some("true"));
+        assert_eq!(params["body"], "W10=");
+
+        // The browser's question before such a request is answered too: the server may not exist.
+        let preflight = from_page(
+            "OPTIONS",
+            json!({
+                "Origin": "http://localhost:5173",
+                "Access-Control-Request-Method": "PUT",
+                "Access-Control-Request-Headers": "content-type,x-token",
+            }),
+        );
+        let (command, params) = answer(&preflight, &rules);
+        assert_eq!((command, &params["responseCode"]), ("Fetch.fulfillRequest", &json!(204)));
+        assert_eq!(header(&params, "Access-Control-Allow-Origin"), Some("http://localhost:5173"));
+        assert_eq!(header(&params, "Access-Control-Allow-Methods"), Some("PUT"));
+        assert_eq!(header(&params, "Access-Control-Allow-Headers"), Some("content-type,x-token"));
+        assert_eq!(params.get("body"), None);
+
+        // Same origin: nothing but the rule's own header.
+        let (_, params) = answer(&from_page("GET", json!({})), &rules);
+        assert_eq!(params["responseHeaders"], json!([{ "name": "Content-Type", "value": "application/json" }]));
+    }
+
+    /// A stand-in for js-debug's CDP proxy: what it receives, and a way to send it events.
+    pub(crate) async fn proxy() -> (String, mpsc::UnboundedReceiver<Value>, mpsc::UnboundedSender<Value>) {
+        proxy_refusing(|_| false).await
+    }
+
+    /// A proxy that answers the commands `refused` picks with an error, like the real one does
+    /// for what it or the browser does not accept.
+    pub(crate) async fn proxy_refusing(
+        refused: fn(&Value) -> bool,
+    ) -> (String, mpsc::UnboundedReceiver<Value>, mpsc::UnboundedSender<Value>) {
+        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let url = format!("ws://127.0.0.1:{}/session", listener.local_addr().unwrap().port());
+        let (received_tx, received) = mpsc::unbounded_channel();
+        let (events, mut events_rx) = mpsc::unbounded_channel::<Value>();
+        tokio::spawn(async move {
+            let (stream, _) = listener.accept().await.unwrap();
+            let (mut write, mut read) = tokio_tungstenite::accept_async(stream).await.unwrap().split();
+            loop {
+                tokio::select! {
+                    message = read.next() => {
+                        let Some(Ok(message)) = message else { break };
+                        let Ok(text) = message.to_text() else { continue };
+                        let Ok(request) = serde_json::from_str::<Value>(text) else { continue };
+                        let reply = if refused(&request) {
+                            json!({ "id": request["id"], "error": { "code": -32602, "message": "refused" } })
+                        } else {
+                            json!({ "id": request["id"], "result": {} })
+                        };
+                        let _ = write.send(Message::text(reply.to_string())).await;
+                        let _ = received_tx.send(request);
+                    }
+                    Some(event) = events_rx.recv() => {
+                        let _ = write.send(Message::text(event.to_string())).await;
+                    }
+                }
+            }
+        });
+        (url, received, events)
+    }
+
+    pub(crate) async fn next(received: &mut mpsc::UnboundedReceiver<Value>) -> (String, Value) {
+        let request = tokio::time::timeout(std::time::Duration::from_secs(5), received.recv())
+            .await
+            .expect("the proxy got a request in time")
+            .expect("the connection is open");
+        (request["method"].as_str().unwrap().to_owned(), request["params"].clone())
+    }
+
+    /// The browser's event for a request it holds.
+    fn held(request_id: &str, url: &str) -> Value {
+        json!({ "method": "Fetch.requestPaused", "params": { "requestId": request_id, "request": { "url": url } } })
+    }
+
+    type Serving = (tokio::task::JoinHandle<()>, oneshot::Receiver<Result<(), String>>);
+
+    fn serving(url: String, rules: watch::Receiver<Vec<JsResponseRule>>) -> Serving {
+        let (ready, is_ready) = oneshot::channel();
+        (tokio::spawn(serve(url, rules, ready)), is_ready)
+    }
+
+    async fn ended(task: tokio::task::JoinHandle<()>) {
+        tokio::time::timeout(std::time::Duration::from_secs(5), task).await.unwrap().unwrap();
+    }
+
+    #[tokio::test]
+    async fn held_requests_are_answered_and_interception_ends_before_the_connection() {
+        let (url, mut received, events) = proxy().await;
+        let (rules, watched) = tokio::sync::watch::channel(vec![rule("api/items", 200, "[]")]);
+        let (serving, ready) = serving(url, watched);
+        assert_eq!(ready.await.unwrap(), Ok(()));
+
+        assert_eq!(
+            next(&mut received).await,
+            ("JsDebug.subscribe".into(), json!({ "events": ["Fetch.requestPaused"] }))
+        );
+        assert_eq!(
+            next(&mut received).await,
+            (
+                "Fetch.enable".into(),
+                json!({ "patterns": [{ "urlPattern": "*api/items*", "requestStage": "Request" }] })
+            )
+        );
+
+        events.send(held("1", "http://h/api/items")).unwrap();
+        let (command, params) = next(&mut received).await;
+        assert_eq!(
+            (command.as_str(), &params["requestId"], &params["responseCode"]),
+            ("Fetch.fulfillRequest", &json!("1"), &json!(200))
+        );
+        events.send(held("2", "http://h/other")).unwrap();
+        assert_eq!(next(&mut received).await, ("Fetch.continueRequest".into(), json!({ "requestId": "2" })));
+
+        // New rules replace the browser's patterns.
+        rules.send(vec![rule("api/users", 404, "{}")]).unwrap();
+        assert_eq!(
+            next(&mut received).await,
+            (
+                "Fetch.enable".into(),
+                json!({ "patterns": [{ "urlPattern": "*api/users*", "requestStage": "Request" }] })
+            )
+        );
+
+        // No rules left: the browser stops holding requests. The connection stays for the
+        // rules that come next, and goes with the session.
+        rules.send(Vec::new()).unwrap();
+        assert_eq!(next(&mut received).await.0, "Fetch.disable");
+        rules.send(vec![rule("api/items", 200, "[]")]).unwrap();
+        assert_eq!(next(&mut received).await.0, "Fetch.enable");
+        rules.send(Vec::new()).unwrap();
+        assert_eq!(next(&mut received).await.0, "Fetch.disable");
+        drop(rules);
+        ended(serving).await;
+        // Already off: not switched off a second time.
+        assert!(received.try_recv().is_err());
+    }
+
+    #[tokio::test]
+    async fn a_session_that_goes_away_switches_interception_off() {
+        let (url, mut received, _events) = proxy().await;
+        let (rules, watched) = tokio::sync::watch::channel(vec![rule("api", 200, "[]")]);
+        let (serving, _ready) = serving(url, watched);
+        assert_eq!(next(&mut received).await.0, "JsDebug.subscribe");
+        assert_eq!(next(&mut received).await.0, "Fetch.enable");
+        drop(rules);
+        assert_eq!(next(&mut received).await.0, "Fetch.disable");
+        ended(serving).await;
+    }
+
+    #[tokio::test]
+    async fn a_response_the_browser_refuses_lets_the_request_through() {
+        let (url, mut received, events) = proxy_refusing(|request| request["method"] == "Fetch.fulfillRequest").await;
+        let (_rules, watched) = tokio::sync::watch::channel(vec![rule("api", 200, "[]")]);
+        let (_serving, _ready) = serving(url, watched);
+        assert_eq!(next(&mut received).await.0, "JsDebug.subscribe");
+        assert_eq!(next(&mut received).await.0, "Fetch.enable");
+        events.send(held("9", "http://h/api")).unwrap();
+        assert_eq!(next(&mut received).await.0, "Fetch.fulfillRequest");
+        // Unanswered, the request would hang the page.
+        assert_eq!(next(&mut received).await, ("Fetch.continueRequest".into(), json!({ "requestId": "9" })));
+    }
+
+    #[tokio::test]
+    async fn a_proxy_that_does_not_report_held_requests_is_not_asked_to_hold_any() {
+        let (url, mut received, _events) = proxy_refusing(|request| request["method"] == "JsDebug.subscribe").await;
+        let (_rules, watched) = tokio::sync::watch::channel(vec![rule("api", 200, "[]")]);
+        let (serving, ready) = serving(url, watched);
+        assert_eq!(next(&mut received).await.0, "JsDebug.subscribe");
+        assert_eq!(ready.await.unwrap(), Err("refused".to_owned()));
+        ended(serving).await;
+        assert!(received.try_recv().is_err());
+    }
+
+    #[tokio::test]
+    async fn no_connection_to_the_proxy_is_reported() {
+        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let url = format!("ws://127.0.0.1:{}/session", listener.local_addr().unwrap().port());
+        drop(listener);
+        let (_rules, watched) = tokio::sync::watch::channel(vec![rule("api", 200, "[]")]);
+        let (serving, ready) = serving(url, watched);
+        assert!(ready.await.unwrap().is_err());
+        ended(serving).await;
+    }
+}

crates/ide-dap/src/js_debug.rs

@@ -11,6 +11,8 @@ use serde::{Deserialize, Serialize};
 use serde_json::{Value, json};
 use specta::Type;
 use std::collections::BTreeMap;
+use std::path::PathBuf;
+use std::sync::atomic::{AtomicU32, Ordering};
 
 pub(crate) const ADAPTER: &str = "js-debug";
 
@@ -25,7 +27,7 @@ pub(crate) fn is_page(session: &Session) -> bool {
 /// Waits until the adapter answered the `launch` of `session`. js-debug sets a page's session
 /// up between `configurationDone` and that answer; a request of its own that arrives then is
 /// answered and has no effect.
-async fn launched(session: &Session) -> bool {
+pub(crate) async fn launched(session: &Session) -> bool {
     let mut launched = session.launched.subscribe();
     let answered = tokio::time::timeout(REQUEST_TIMEOUT, launched.wait_for(|answered| *answered)).await;
     matches!(answered, Ok(Ok(_)))
@@ -59,6 +61,44 @@ impl DebugManager {
         self.js_page_request(s, "setCustomBreakpoints", json!({ "ids": ids, "xhr": xhr })).await?;
         Ok(())
     }
+
+    /// Starts recording the page's CPU profile; [`Self::js_stop_profile`] ends it.
+    pub async fn js_start_profile(&self, s: DebugSessionId) -> IdeResult<()> {
+        self.js_page_request(s, "startProfile", json!({ "type": "cpu" })).await?;
+        Ok(())
+    }
+
+    /// Ends the recording and returns a new directory holding it as `page.cpuprofile`
+    /// (what `ide-profiler` reads a directory of).
+    pub async fn js_stop_profile(&self, s: DebugSessionId) -> IdeResult<PathBuf> {
+        let session = self.session(s)?;
+        // js-debug names the file it records into when the recording starts.
+        let Some(recorded) = session.js_profile.lock().take() else {
+            return Err(IdeError::invalid("no CPU profile is being recorded"));
+        };
+        self.js_page_request(s, "stopProfile", json!({})).await?;
+        static HANDED_OVER: AtomicU32 = AtomicU32::new(0);
+        let dir = std::env::temp_dir().join(format!(
+            "openidea-js-profile-{}-{}-{}",
+            std::process::id(),
+            s.0,
+            HANDED_OVER.fetch_add(1, Ordering::Relaxed)
+        ));
+        let copied = tokio::task::spawn_blocking({
+            let dir = dir.clone();
+            move || {
+                std::fs::create_dir_all(&dir)?;
+                std::fs::copy(&recorded, dir.join("page.cpuprofile"))?;
+                // The adapter's own copy is in the system's temporary directory: no use keeping two.
+                let _ = std::fs::remove_file(&recorded);
+                Ok::<_, std::io::Error>(())
+            }
+        })
+        .await
+        .map_err(|e| IdeError::internal(e.to_string()))?;
+        copied.map_err(|e| IdeError::unavailable(format!("the recorded CPU profile cannot be read: {e}")))?;
+        Ok(dir)
+    }
 }
 
 /// The browser events js-debug is asked to pass on (`enableNetworking`'s `mirrorEvents`).

crates/ide-dap/src/lib.rs

@@ -13,6 +13,7 @@ pub mod attach;
 mod cargo;
 pub mod connection;
 pub mod jdwp;
+mod js_cdp;
 mod js_debug;
 mod jvm_memory;
 pub mod kotlin;
@@ -24,6 +25,7 @@ use connection::{Connection, DapError};
 use futures::future::join_all;
 use ide_core::{DebugSessionId, IdeError, IdeResult, SharedSink};
 use ide_language::LanguageRegistry;
+pub use js_cdp::JsResponseRule;
 pub use js_debug::JsResponseBody;
 pub use jvm_memory::*;
 use parking_lot::Mutex;

crates/ide-dap/src/session.rs

@@ -94,6 +94,11 @@ pub(crate) struct Session {
     /// The `type` of the launch or attach request (js-debug's `pwa-node`, `pwa-chrome`); a child
     /// session's comes from the configuration the adapter started it with.
     pub launch_type: std::sync::OnceLock<String>,
+    /// The response rules of a page once a connection applies them (`js_cdp::serve`).
+    /// Dropped with the session, which switches the browser's interception off.
+    pub js_overrides: tokio::sync::Mutex<Option<tokio::sync::watch::Sender<Vec<crate::JsResponseRule>>>>,
+    /// The file js-debug records the page's CPU profile into, while one is being recorded.
+    pub js_profile: parking_lot::Mutex<Option<std::path::PathBuf>>,
     pub jvm_inspector: parking_lot::Mutex<Option<Arc<dyn ide_jvm_inspect::JvmInspector>>>,
     /// One inspector request per session at a time.
     pub inspect_lock: tokio::sync::Mutex<()>,
@@ -255,6 +260,8 @@ impl Session {
             progress: Mutex::new(HashMap::new()),
             jdwp_link: parking_lot::Mutex::new(None),
             launch_type: std::sync::OnceLock::new(),
+            js_overrides: tokio::sync::Mutex::new(None),
+            js_profile: parking_lot::Mutex::new(None),
             jvm_inspector: parking_lot::Mutex::new(None),
             inspect_lock: tokio::sync::Mutex::default(),
             ended: ide_core::CancellationToken::new(),
@@ -842,6 +849,10 @@ async fn on_event(mgr: &Arc<DebugManager>, s: &Arc<Session>, event: &str, mut bo
                 s.emit(DebugEvent::JsNetwork { event });
             }
         }
+        // js-debug, after `startProfile`: where it records the profile.
+        "profileStarted" => {
+            *s.js_profile.lock() = str_("file").map(std::path::PathBuf::from);
+        }
         _ => tracing::trace!("dap: ignored event {event}"),
     }
 }

crates/ide-dap/src/tests.rs

@@ -1104,6 +1104,142 @@ async fn a_page_whose_requests_the_adapter_does_not_report_says_so() {
     h.wait_event(|e| matches!(e, DebugEvent::JsNetworkUnavailable)).await;
 }
 
+/// Where the fake adapter says its CDP proxy listens (`requestCDPProxy`).
+static CDP_PROXY_PORT: std::sync::atomic::AtomicU16 = std::sync::atomic::AtomicU16::new(0);
+
+fn proxy_adapter(msg: &Value) -> Option<CustomReply> {
+    let port = CDP_PROXY_PORT.load(std::sync::atomic::Ordering::Relaxed);
+    (msg["command"] == "requestCDPProxy")
+        .then(|| (json!({ "host": "127.0.0.1", "port": port, "path": "/session" }), Vec::new()))
+}
+
+#[tokio::test]
+async fn response_overrides_reach_the_page_through_the_adapters_proxy() {
+    use crate::js_cdp::tests::{next, proxy, rule};
+    let (url, mut received, _events) = proxy().await;
+    let port: u16 = url.trim_start_matches("ws://127.0.0.1:").trim_end_matches("/session").parse().unwrap();
+    CDP_PROXY_PORT.store(port, std::sync::atomic::Ordering::Relaxed);
+
+    let h = harness(Script {
+        start_debugging: true,
+        custom: Some(proxy_adapter),
+        child_launch_delay: Duration::from_millis(150),
+        ..Script::default()
+    });
+    let browser = h.start(js_config("pwa-chrome")).await.unwrap();
+    let page = child_of(&h, browser).await;
+
+    // Rules that are there as the page starts wait until its session takes requests.
+    tokio::time::sleep(Duration::from_millis(50)).await;
+    h.manager.js_set_response_overrides(page, vec![rule("api/items", 200, "[]")]).await.unwrap();
+    let dropped = h.log.lock().iter().filter(|m| m["type"] == "dropped").count();
+    assert_eq!(dropped, 0, "the proxy was asked for before the page took requests");
+    assert_eq!(next(&mut received).await.0, "JsDebug.subscribe");
+    assert_eq!(
+        next(&mut received).await,
+        ("Fetch.enable".into(), json!({ "patterns": [{ "urlPattern": "*api/items*", "requestStage": "Request" }] }))
+    );
+    // Changed rules go over the connection that is open: the proxy is asked for once.
+    h.manager.js_set_response_overrides(page, vec![rule("api/users", 200, "[]")]).await.unwrap();
+    assert_eq!(next(&mut received).await.1["patterns"][0]["urlPattern"], "*api/users*");
+    assert_eq!(requests(&h, "requestCDPProxy").len(), 1);
+
+    h.manager.js_set_response_overrides(page, Vec::new()).await.unwrap();
+    assert_eq!(next(&mut received).await.0, "Fetch.disable");
+    // A rule switched back on.
+    h.manager.js_set_response_overrides(page, vec![rule("api/items", 200, "[]")]).await.unwrap();
+    assert_eq!(next(&mut received).await.0, "Fetch.enable");
+    assert_eq!(requests(&h, "requestCDPProxy").len(), 1);
+
+    let not_a_page = h.manager.js_set_response_overrides(browser, vec![rule("api", 200, "")]).await.unwrap_err();
+    assert_eq!(not_a_page.kind, ide_core::error::ErrorKind::Unavailable);
+}
+
+#[tokio::test]
+async fn response_overrides_are_unavailable_without_the_adapters_proxy() {
+    use crate::js_cdp::tests::rule;
+    let h = harness(Script { start_debugging: true, ..Script::default() });
+    let browser = h.start(js_config("pwa-chrome")).await.unwrap();
+    let page = child_of(&h, browser).await;
+    let refused = h.manager.js_set_response_overrides(page, vec![rule("api", 200, "")]).await.unwrap_err();
+    assert_eq!(refused.kind, ide_core::error::ErrorKind::Unavailable);
+    // Nothing to switch off is not an error.
+    h.manager.js_set_response_overrides(page, Vec::new()).await.unwrap();
+}
+
+/// A port nothing listens on, which the fake adapter gives as its CDP proxy.
+static DEAD_PROXY_PORT: std::sync::atomic::AtomicU16 = std::sync::atomic::AtomicU16::new(0);
+
+fn dead_proxy_adapter(msg: &Value) -> Option<CustomReply> {
+    let port = DEAD_PROXY_PORT.load(std::sync::atomic::Ordering::Relaxed);
+    (msg["command"] == "requestCDPProxy")
+        .then(|| (json!({ "host": "127.0.0.1", "port": port, "path": "/session" }), Vec::new()))
+}
+
+#[tokio::test]
+async fn response_overrides_that_cannot_reach_the_browser_are_an_error() {
+    use crate::js_cdp::tests::rule;
+    let listener = std::net::TcpListener::bind("127.0.0.1:0").unwrap();
+    DEAD_PROXY_PORT.store(listener.local_addr().unwrap().port(), std::sync::atomic::Ordering::Relaxed);
+    drop(listener);
+
+    let h = harness(Script { start_debugging: true, custom: Some(dead_proxy_adapter), ..Script::default() });
+    let browser = h.start(js_config("pwa-chrome")).await.unwrap();
+    let page = child_of(&h, browser).await;
+    let unreachable = h.manager.js_set_response_overrides(page, vec![rule("api", 200, "")]).await.unwrap_err();
+    assert_eq!(unreachable.kind, ide_core::error::ErrorKind::Unavailable);
+    // The next rules try again instead of going to a connection that never was.
+    let again = h.manager.js_set_response_overrides(page, vec![rule("api", 200, "")]).await.unwrap_err();
+    assert_eq!(again.kind, ide_core::error::ErrorKind::Unavailable);
+    assert_eq!(requests(&h, "requestCDPProxy").len(), 2);
+}
+
+/// The file the fake adapter says it records a CPU profile into (`profileStarted`).
+static PROFILE_FILE: parking_lot::Mutex<String> = parking_lot::Mutex::new(String::new());
+
+fn profiling_adapter(msg: &Value) -> Option<CustomReply> {
+    match msg["command"].as_str()? {
+        "startProfile" => {
+            Some((json!({}), vec![("profileStarted", json!({ "file": *PROFILE_FILE.lock(), "type": "cpu" }))]))
+        }
+        "stopProfile" => Some((json!({}), vec![("profilerStateUpdate", json!({ "label": "", "running": false }))])),
+        _ => None,
+    }
+}
+
+#[tokio::test]
+async fn a_pages_cpu_profile_is_handed_over_as_a_cpuprofile_file() {
+    let recorded = std::env::temp_dir().join(format!("openidea-dap-profile-{}", std::process::id()));
+    std::fs::write(&recorded, r#"{"nodes":[],"samples":[]}"#).unwrap();
+    *PROFILE_FILE.lock() = recorded.to_string_lossy().into_owned();
+
+    let h = harness(Script { start_debugging: true, custom: Some(profiling_adapter), ..Script::default() });
+    let browser = h.start(js_config("pwa-chrome")).await.unwrap();
+    let page = child_of(&h, browser).await;
+
+    // Nothing is being recorded yet.
+    let idle = h.manager.js_stop_profile(page).await.unwrap_err();
+    assert_eq!(idle.kind, ide_core::error::ErrorKind::InvalidInput);
+
+    h.manager.js_start_profile(page).await.unwrap();
+    assert_eq!(requests(&h, "startProfile"), [json!({ "type": "cpu" })]);
+    let dir = h.manager.js_stop_profile(page).await.unwrap();
+    assert_eq!(requests(&h, "stopProfile").len(), 1);
+    let files: Vec<_> = std::fs::read_dir(&dir).unwrap().map(|e| e.unwrap().file_name()).collect();
+    assert_eq!(files, ["page.cpuprofile"]);
+    assert_eq!(std::fs::read_to_string(dir.join("page.cpuprofile")).unwrap(), r#"{"nodes":[],"samples":[]}"#);
+    // One recording is handed over once.
+    assert_eq!(h.manager.js_stop_profile(page).await.unwrap_err().kind, ide_core::error::ErrorKind::InvalidInput);
+
+    // The adapter's file isn't there when it is asked for (the hand-over above took the first one).
+    assert!(!recorded.exists());
+    h.manager.js_start_profile(page).await.unwrap();
+    assert_eq!(h.manager.js_stop_profile(page).await.unwrap_err().kind, ide_core::error::ErrorKind::Unavailable);
+
+    assert_eq!(h.manager.js_start_profile(browser).await.unwrap_err().kind, ide_core::error::ErrorKind::Unavailable);
+    let _ = std::fs::remove_dir_all(dir);
+}
+
 #[test]
 fn a_child_session_is_named_by_the_adapter_unless_it_is_a_blank_page() {
     assert_eq!(child_name(&json!({ "name": "server.js [4120]" }), "Server"), "server.js [4120]");

crates/ide-docker/src/lib.rs

@@ -542,6 +542,24 @@ pub fn compose_config(ep: &DockerEndpoint, dir: &Path, files: &[String]) -> IdeR
     if out.success { Ok(out.stdout) } else { Err(failure(&args, &out.stderr, &out.stdout)) }
 }
 
+/// Runs the docker CLI with `args` in `dir` and returns its standard output; a non-zero
+/// exit is an error with docker's message.
+pub fn cli(
+    ep: &DockerEndpoint,
+    dir: Option<&Path>,
+    args: &[String],
+    timeout: Duration,
+    cancel: Option<&CancellationToken>,
+) -> IdeResult<String> {
+    let args: Vec<&str> = args.iter().map(String::as_str).collect();
+    let mut cmd = command(ep, &args)?;
+    if let Some(dir) = dir {
+        cmd.current_dir(dir);
+    }
+    let out = process::run(cmd, timeout, cancel)?;
+    if out.success { Ok(out.stdout) } else { Err(failure(&args, &out.stderr, &out.stdout)) }
+}
+
 #[cfg(test)]
 mod local_tests {
     use super::*;

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

@@ -382,6 +382,15 @@ pub async fn debug_js_custom_breakpoints(
     host.debugger.js_set_custom_breakpoints(session, ids, xhr).await
 }
 
+pub async fn debug_js_response_overrides(
+    host: &Host,
+    _window: &str,
+    session: DebugSessionId,
+    rules: Vec<ide_dap::JsResponseRule>,
+) -> IdeResult<()> {
+    host.debugger.js_set_response_overrides(session, rules).await
+}
+
 pub async fn debug_js_response_body(
     host: &Host,
     _window: &str,
@@ -391,6 +400,18 @@ pub async fn debug_js_response_body(
     host.debugger.js_response_body(session, request_id).await
 }
 
+pub async fn debug_js_start_profile(host: &Host, _window: &str, session: DebugSessionId) -> IdeResult<()> {
+    host.debugger.js_start_profile(session).await
+}
+
+pub async fn debug_js_stop_profile(
+    host: &Host,
+    _window: &str,
+    session: DebugSessionId,
+) -> IdeResult<ide_core::IpcPath> {
+    host.debugger.js_stop_profile(session).await.map(Into::into)
+}
+
 pub fn debug_capabilities(host: &Host, _window: &str, session: DebugSessionId) -> IdeResult<DebugCapabilities> {
     host.debugger.capabilities(session)
 }
@@ -607,12 +628,23 @@ pub(crate) fn register(d: &mut Dispatcher) {
         debug_restart_frame(&c.host, &c.window, c.arg("session")?, c.arg("frameId")?).await
     });
     d.add("debug_capabilities", |c| async move { debug_capabilities(&c.host, &c.window, c.arg("session")?) });
+    d.add("debug_js_response_overrides", |c| async move {
+        debug_js_response_overrides(&c.host, &c.window, c.arg("session")?, c.arg("rules")?).await
+    });
     d.add("debug_js_response_body", |c| async move {
         debug_js_response_body(&c.host, &c.window, c.arg("session")?, c.arg("requestId")?).await
     });
     d.add("debug_js_custom_breakpoints", |c| async move {
         debug_js_custom_breakpoints(&c.host, &c.window, c.arg("session")?, c.arg("ids")?, c.arg("xhr")?).await
     });
+    d.add(
+        "debug_js_start_profile",
+        |c| async move { debug_js_start_profile(&c.host, &c.window, c.arg("session")?).await },
+    );
+    d.add(
+        "debug_js_stop_profile",
+        |c| async move { debug_js_stop_profile(&c.host, &c.window, c.arg("session")?).await },
+    );
     d.add("debug_set_function_breakpoints", |c| async move {
         debug_set_function_breakpoints(&c.host, &c.window, c.arg("breakpoints")?).await
     });

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

@@ -159,6 +159,15 @@ pub async fn doc_highlights(host: &Host, window: &str, doc: DocId) -> IdeResult<
     .await
 }
 
+/// Python class facts the inheritance inspections read: base names as written, a method's
+/// parameters, decorator semantics and its body shape. Tree-sitter answers; no LSP.
+pub async fn doc_python_facts(host: &Host, window: &str, doc: DocId) -> IdeResult<ide_language::PythonFacts> {
+    let project = host.project(window)?;
+    let syntax = host.syntax();
+    let snap = project.documents.text_snapshot(doc)?;
+    blocking(move || Ok(syntax.python_facts(&snap.language, &snap.text))).await
+}
+
 /// Extend Selection (⌥↑): syntax ranges around `offset`, innermost first.
 /// Large documents fall back to word / line / document ranges.
 pub async fn doc_selection_ranges(host: &Host, window: &str, doc: DocId, offset: u32) -> IdeResult<Vec<Range>> {
@@ -208,6 +217,7 @@ pub(crate) fn register(d: &mut Dispatcher) {
     d.add("doc_outline", |c| async move { doc_outline(&c.host, &c.window, c.arg("doc")?).await });
     d.add("doc_folding", |c| async move { doc_folding(&c.host, &c.window, c.arg("doc")?).await });
     d.add("doc_highlights", |c| async move { doc_highlights(&c.host, &c.window, c.arg("doc")?).await });
+    d.add("doc_python_facts", |c| async move { doc_python_facts(&c.host, &c.window, c.arg("doc")?).await });
     d.add("doc_selection_ranges", |c| async move {
         doc_selection_ranges(&c.host, &c.window, c.arg("doc")?, c.arg("offset")?).await
     });

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

@@ -1472,6 +1472,15 @@ pub async fn lsp_type_hierarchy(
     host.project(window)?.lsp.type_hierarchy(doc, pos, direction).await
 }
 
+pub async fn lsp_prepare_type_hierarchy(
+    host: &Host,
+    window: &str,
+    doc: DocId,
+    pos: Pos,
+) -> IdeResult<Option<HierarchyItem>> {
+    host.project(window)?.lsp.prepare_type_hierarchy(doc, pos).await
+}
+
 pub fn lsp_servers(host: &Host, window: &str) -> IdeResult<Vec<ServerInfo>> {
     Ok(host.project(window)?.lsp.servers())
 }
@@ -1856,6 +1865,9 @@ pub(crate) fn register(d: &mut Dispatcher) {
     d.add("lsp_type_hierarchy", |c| async move {
         lsp_type_hierarchy(&c.host, &c.window, c.arg("doc")?, c.arg("pos")?, c.arg("direction")?).await
     });
+    d.add("lsp_prepare_type_hierarchy", |c| async move {
+        lsp_prepare_type_hierarchy(&c.host, &c.window, c.arg("doc")?, c.arg("pos")?).await
+    });
     d.add("lsp_servers", |c| async move { lsp_servers(&c.host, &c.window) });
     d.add("lsp_resend_diagnostics", |c| async move { lsp_resend_diagnostics(&c.host, &c.window) });
     d.add("lsp_restart", |c| async move { lsp_restart(&c.host, &c.window, c.arg("server")?).await });

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

@@ -239,6 +239,12 @@ pub fn set_settings(
     let toolchain = ["languages", "tools", "languageServers", "projectStructure"]
         .iter()
         .any(|k| key == *k || key.starts_with(&format!("{k}.")));
+    // A run target chosen as the Python interpreter (or changed) needs a snapshot of its libraries.
+    if ["languages", "languages.python", "languages.python.interpreter", "runTargets"].contains(&key) {
+        for project in affected() {
+            crate::ops::sdk::container_python::ensure(host, &project);
+        }
+    }
     // Code style only reaches servers as settings (e.g. jdtls' formatter profile); builds don't depend on it.
     if code_style || toolchain {
         for project in affected() {

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

@@ -508,7 +508,7 @@ pub fn list(host: &Host) -> Vec<RunInfo> {
 }
 
 mod commands;
-mod container;
+pub(crate) mod container;
 pub use commands::*;
 
 #[cfg(test)]

crates/ide-host/src/ops/run/container.rs

@@ -33,23 +33,11 @@ pub(super) async fn prepare(host: &Host, root: &Path, target: RunTarget, config:
     let root = root.to_path_buf();
     let data_dir = host.data_dir.clone();
     host.blocking(move || {
-        if !ide_docker::endpoint_is_local(&endpoint)? {
-            return Err(IdeError::invalid(format!(
-                "Run target '{}' uses a Docker daemon on another machine: the project can only be mounted from a local one",
-                target.name
-            )));
-        }
+        require_local(&endpoint, &target)?;
         let docker = ide_docker::docker_executable().ok_or_else(|| {
             IdeError::unavailable("docker executable not found; install Docker and make sure it is on PATH")
         })?;
-        let container_root = match target.container_root.trim() {
-            "" if target.kind == RunTargetKind::Compose => {
-                let json = ide_docker::compose_config(&endpoint, &root, &target.compose_files)?;
-                compose_container_root(&json, target.service.trim(), &root)?
-            }
-            "" => default_container_root(&root),
-            folder => folder.to_owned(),
-        };
+        let container_root = container_root(&endpoint, &root, &target)?;
         let file_env = env_files(&root, &config)?;
         let name = container_name(&config.id, &unique());
         let debugging = if debug { Some(Debugging::prepare(&data_dir)?) } else { None };
@@ -75,6 +63,29 @@ pub(super) async fn prepare(host: &Host, root: &Path, target: RunTarget, config:
     .await
 }
 
+/// The project can only be bind-mounted from a daemon on this machine.
+pub(crate) fn require_local(endpoint: &DockerEndpoint, target: &RunTarget) -> IdeResult<()> {
+    if !ide_docker::endpoint_is_local(endpoint)? {
+        return Err(IdeError::invalid(format!(
+            "Run target '{}' uses a Docker daemon on another machine: the project can only be mounted from a local one",
+            target.name
+        )));
+    }
+    Ok(())
+}
+
+/// Where the project is in the target's containers.
+pub(crate) fn container_root(endpoint: &DockerEndpoint, root: &Path, target: &RunTarget) -> IdeResult<String> {
+    Ok(match target.container_root.trim() {
+        "" if target.kind == RunTargetKind::Compose => {
+            let json = ide_docker::compose_config(endpoint, root, &target.compose_files)?;
+            compose_container_root(&json, target.service.trim(), root)?
+        }
+        "" => default_container_root(root),
+        folder => folder.to_owned(),
+    })
+}
+
 /// What a debug run mounts and publishes.
 struct Debugging {
     port: u16,
@@ -104,7 +115,7 @@ fn free_port() -> IdeResult<u16> {
 }
 
 /// The target's Docker connection (Services tool window), by id; none = the CLI's daemon.
-fn endpoint(data_dir: &Path, target: &RunTarget) -> IdeResult<DockerEndpoint> {
+pub(crate) fn endpoint(data_dir: &Path, target: &RunTarget) -> IdeResult<DockerEndpoint> {
     let id = target.docker_connection.trim();
     if id.is_empty() {
         return Ok(DockerEndpoint::Default);

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

@@ -10,6 +10,9 @@ use std::path::PathBuf;
 use std::sync::Mutex;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
+pub(crate) mod container_python;
+pub use container_python::{ContainerPython, sdk_container_python, sdk_container_python_refresh};
+
 fn join_err(e: impl std::fmt::Display) -> IdeError {
     IdeError::internal(e.to_string())
 }
@@ -232,12 +235,17 @@ pub async fn sdk_project_libraries(
     let project = host.project(window)?;
     let (root, cache, settings) = (project.root.clone(), project.build_cache_dir(), project.settings.effective());
     let cancel = host.begin_project_request(window, request);
+    let container = container_python::library_group(host, &root, &settings);
     let libraries = {
         let (root, settings, cancel, on_groups) = (root.clone(), settings.clone(), cancel.clone(), on_groups.clone());
         tokio::task::spawn_blocking(move || {
-            ide_sdk::libraries::project_libraries_stream(&root, &settings, &[], &cancel, &|groups| {
+            if let Some(group) = &container {
+                let _ = on_groups.send(vec![group.clone()]);
+            }
+            let groups = ide_sdk::libraries::project_libraries_stream(&root, &settings, &[], &cancel, &|groups| {
                 let _ = on_groups.send(groups);
-            })
+            });
+            container.into_iter().chain(groups).collect::<Vec<_>>()
         })
     };
     let dependencies = {
@@ -377,6 +385,8 @@ pub(crate) fn register(d: &mut Dispatcher) {
     );
     d.add("sdk_python_effective", |c| async move { sdk_python_effective(&c.host, &c.window, c.arg("near")?) });
     d.add("sdk_php_effective", |c| async move { sdk_php_effective(&c.host, &c.window) });
+    d.add("sdk_container_python", |c| async move { sdk_container_python(&c.host, &c.window) });
+    d.add("sdk_container_python_refresh", |c| async move { sdk_container_python_refresh(&c.host, &c.window).await });
     d.add("sdk_php_xdebug", |c| async move { sdk_php_xdebug(&c.host, &c.window, c.arg("php")?, c.arg("cwd")?).await });
     d.add(
         "sdk_php_language_level",

crates/ide-host/src/ops/sdk/container_python.rs

@@ -0,0 +1,298 @@
+//! A Docker or Compose run target's Python as the project interpreter: snapshots of the
+//! container's library folders for the language server (see `ide_sdk::container_python`).
+//!
+//! A snapshot runs the target's Python once in a new container (the image's entrypoint
+//! and the service's dependencies skipped), then copies its `sys.path` folders out of
+//! the stopped container with `docker cp`. Nothing is installed in the container.
+
+use crate::Host;
+use crate::project::Project;
+use ide_core::event::NotifyLevel;
+use ide_core::remote_settings::{RunTarget, RunTargetKind};
+use ide_core::settings::Settings;
+use ide_core::{IdeError, IdeEvent, IdeResult, IpcPath, TaskId};
+use ide_sdk::container_python::{self as snapshots, Snapshot};
+use ide_sdk::python::PythonPackage;
+use std::collections::HashSet;
+use std::path::{Path, PathBuf};
+use std::sync::{Arc, LazyLock, Mutex};
+use std::time::Duration;
+
+/// Building or pulling the image may come first.
+const PROBE_TIMEOUT: Duration = Duration::from_secs(15 * 60);
+const COPY_TIMEOUT: Duration = Duration::from_secs(10 * 60);
+const QUICK: Duration = Duration::from_secs(30);
+
+/// The project interpreter when it is a run target's.
+#[derive(Clone, Debug, serde::Serialize, specta::Type)]
+#[serde(rename_all = "camelCase")]
+pub struct ContainerPython {
+    /// The run target's id.
+    pub target: String,
+    /// Its name; empty when no run target has the id.
+    pub name: String,
+    /// The Python version of the snapshot in use; `None`: no snapshot yet.
+    pub version: Option<String>,
+    /// The image the snapshot was copied from.
+    pub image: Option<String>,
+    /// The copied library folders on this machine.
+    pub folders: Vec<IpcPath>,
+    /// Packages of the snapshot (read-only).
+    pub packages: Vec<PythonPackage>,
+    /// A snapshot is being taken.
+    pub updating: bool,
+}
+
+/// Where snapshots are kept, and the Docker connections the targets refer to.
+#[derive(Clone)]
+struct Dirs {
+    data: PathBuf,
+    /// `<local data>/container-python/`: `<project>/<target>/<image>/` and `neutral/`.
+    cache: PathBuf,
+}
+
+impl Dirs {
+    fn of(host: &Host) -> Self {
+        Self::new(&host.data_dir, &host.local_data_dir)
+    }
+
+    fn new(data_dir: &Path, local_data_dir: &Path) -> Self {
+        Self { data: data_dir.to_path_buf(), cache: local_data_dir.join("container-python") }
+    }
+
+    fn target(&self, root: &Path, target: &str) -> PathBuf {
+        snapshots::target_dir(&self.cache.join(crate::project::project_key(root)), target)
+    }
+}
+
+/// Target folders with a snapshot being taken.
+static UPDATING: LazyLock<Mutex<HashSet<PathBuf>>> = LazyLock::new(Default::default);
+
+fn updating(dir: &Path) -> bool {
+    UPDATING.lock().unwrap_or_else(|e| e.into_inner()).contains(dir)
+}
+
+/// The snapshot in use for the project's interpreter, if it is a run target's.
+fn current(dirs: &Dirs, root: &Path, settings: &Settings) -> Option<(PathBuf, Snapshot)> {
+    let target = settings.languages.python.run_target()?;
+    snapshots::current(&dirs.target(root, target))
+}
+
+/// Language server configuration: basedpyright / pyright see the container's libraries.
+pub(crate) fn configure_server(
+    cfg: &mut ide_language::LanguageServerConfig,
+    local_data_dir: &Path,
+    root: &Path,
+    settings: &Settings,
+) {
+    if settings.languages.python.run_target().is_none() {
+        return;
+    }
+    let current = current(&Dirs::new(local_data_dir, local_data_dir), root, settings);
+    snapshots::configure_server(cfg, current.as_ref().map(|(d, s)| (d.as_path(), s)));
+}
+
+/// External Libraries: the snapshot's folders, named after the run target.
+pub(crate) fn library_group(host: &Host, root: &Path, settings: &Settings) -> Option<ide_sdk::libraries::LibraryGroup> {
+    let target = settings.languages.python.run_target()?;
+    let (dir, snapshot) = current(&Dirs::of(host), root, settings)?;
+    let name = settings.run_targets.iter().find(|t| t.id == target).map_or(target, |t| t.name.as_str());
+    snapshots::library_group(name, &dir, &snapshot)
+}
+
+/// The project interpreter when it is a run target's, with its snapshot.
+pub fn sdk_container_python(host: &Host, window: &str) -> IdeResult<Option<ContainerPython>> {
+    host.require_trust(window)?;
+    let project = host.project(window)?;
+    Ok(describe(host, &project.root, &project.settings.effective()))
+}
+
+fn describe(host: &Host, root: &Path, settings: &Settings) -> Option<ContainerPython> {
+    let target = settings.languages.python.run_target()?;
+    let name = settings.run_targets.iter().find(|t| t.id == target).map(|t| t.name.clone()).unwrap_or_default();
+    let dir = Dirs::of(host).target(root, target);
+    let mut out = ContainerPython {
+        target: target.to_owned(),
+        name,
+        version: None,
+        image: None,
+        folders: Vec::new(),
+        packages: Vec::new(),
+        updating: updating(&dir),
+    };
+    if let Some((dir, snapshot)) = snapshots::current(&dir) {
+        out.folders = snapshots::local_folders(&dir, &snapshot).into_iter().map(Into::into).collect();
+        out.packages = snapshots::packages(&dir, &snapshot);
+        out.version = Some(snapshot.probe.version);
+        out.image = Some(snapshot.image);
+    }
+    Some(out)
+}
+
+/// Takes a new snapshot of the project interpreter's container (also of an image that
+/// has one already), then the language servers pick it up.
+pub async fn sdk_container_python_refresh(host: &Host, window: &str) -> IdeResult<Option<ContainerPython>> {
+    host.require_trust(window)?;
+    let project = host.project(window)?;
+    update(Dirs::of(host), &project, true).await?;
+    Ok(describe(host, &project.root, &project.settings.effective()))
+}
+
+/// Takes a snapshot when the project interpreter is a run target's and the current image
+/// has none yet (a new choice, a rebuilt image), in the background. Errors are notified.
+pub(crate) fn ensure(host: &Host, project: &Arc<Project>) {
+    if !project.is_trusted() || project.settings.effective().languages.python.run_target().is_none() {
+        return;
+    }
+    let (dirs, project) = (Dirs::of(host), project.clone());
+    host.runtime.spawn(async move {
+        if let Err(e) = update(dirs, &project, false).await
+            && e.kind != ide_core::error::ErrorKind::Cancelled
+        {
+            project.sink.emit(IdeEvent::Notify {
+                level: NotifyLevel::Warning,
+                title: "Cannot copy the container's Python libraries".into(),
+                body: Some(e.message),
+            });
+        }
+    });
+}
+
+async fn update(dirs: Dirs, project: &Arc<Project>, force: bool) -> IdeResult<()> {
+    let settings = project.settings.effective();
+    let Some(id) = settings.languages.python.run_target() else { return Ok(()) };
+    let target = ide_remote::service::run_target(&settings, id)?;
+    if target.kind == RunTargetKind::Ssh {
+        return Err(IdeError::invalid(format!(
+            "Run target '{}' runs over SSH: only a Docker or Compose run target can be the project interpreter",
+            target.name
+        )));
+    }
+    let dir = dirs.target(&project.root, id);
+    if !UPDATING.lock().unwrap_or_else(|e| e.into_inner()).insert(dir.clone()) {
+        return Ok(());
+    }
+    let _done = Updating(dir.clone());
+    let endpoint = crate::ops::run::container::endpoint(&dirs.data, &target)?;
+    let task = TaskId::next();
+    let title = format!("Python libraries of {}", target.name);
+    let (root, sink) = (project.root.clone(), project.sink.clone());
+    let progress = move |message: &str, done: bool| {
+        sink.emit(IdeEvent::Task {
+            id: task,
+            title: title.clone(),
+            message: Some(message.to_owned()),
+            fraction: None,
+            done,
+            cancellable: false,
+        })
+    };
+    let report = progress.clone();
+    let result = tokio::task::spawn_blocking(move || {
+        take(&endpoint, &root, &target, &dir, &dirs.cache, force, &|message| report(message, false))
+    })
+    .await
+    .map_err(|e| IdeError::internal(e.to_string()))
+    .and_then(|r| r);
+    progress(if result.is_ok() { "Done" } else { "Failed" }, true);
+    if result? {
+        project.lsp.reconfigure().await;
+    }
+    Ok(())
+}
+
+struct Updating(PathBuf);
+
+impl Drop for Updating {
+    fn drop(&mut self) {
+        UPDATING.lock().unwrap_or_else(|e| e.into_inner()).remove(&self.0);
+    }
+}
+
+/// Removes the probe container, also when copying failed.
+struct Container<'a> {
+    endpoint: &'a ide_docker::DockerEndpoint,
+    name: String,
+}
+
+impl Drop for Container<'_> {
+    fn drop(&mut self) {
+        let args = ["rm", "--force", "--volumes", &self.name].map(String::from);
+        if let Err(e) = ide_docker::cli(self.endpoint, None, &args, QUICK, None) {
+            tracing::warn!("cannot remove container {}: {}", self.name, e.message);
+        }
+    }
+}
+
+/// Takes the snapshot in `target_dir` and makes it the one in use; `false` when the image
+/// had one already and it is in use (unless `force`).
+fn take(
+    endpoint: &ide_docker::DockerEndpoint,
+    root: &Path,
+    target: &RunTarget,
+    target_dir: &Path,
+    cache: &Path,
+    force: bool,
+    progress: &dyn Fn(&str),
+) -> IdeResult<bool> {
+    crate::ops::run::container::require_local(endpoint, target)?;
+    let container_root = crate::ops::run::container::container_root(endpoint, root, target)?;
+    let name = format!("openidea-python-{}", unique());
+    let args = ide_remote::docker::python_probe_args(target, root, &name, snapshots::PROBE)?;
+    progress("Starting the container's Python");
+    let container = Container { endpoint, name };
+    let out = ide_docker::cli(endpoint, Some(root), &args, PROBE_TIMEOUT, None);
+    let probe = snapshots::parse_probe(&out?)?;
+    let inspect = ["inspect".into(), "--format".into(), "{{.Image}}".into(), container.name.clone()];
+    let image = ide_docker::cli(endpoint, None, &inspect, QUICK, None)?.trim().to_owned();
+    if image.is_empty() {
+        return Err(IdeError::internal(format!("docker inspect printed no image for {}", container.name)));
+    }
+    let dir = target_dir.join(snapshots::dir_name(&image));
+    let before = snapshots::current(target_dir).map(|(_, s)| s.image);
+    if !force && snapshots::read(&dir).is_some() {
+        snapshots::make_current(target_dir, &image)?;
+        return Ok(before.as_deref() != Some(image.as_str()));
+    }
+    let partial = target_dir.join(format!("{}.partial", snapshots::dir_name(&image)));
+    if partial.exists() {
+        std::fs::remove_dir_all(&partial)?;
+    }
+    std::fs::create_dir_all(&partial)?;
+    let mut folders = Vec::new();
+    for folder in snapshots::folders_to_copy(&probe, &container_root) {
+        progress(&format!("Copying {folder}"));
+        let local = snapshots::local_folder(&partial, &folder);
+        let Some(parent) = local.parent() else { continue };
+        std::fs::create_dir_all(parent)?;
+        // Into an existing folder: `docker cp` puts the source folder in it under its own name.
+        let args = ["cp".into(), format!("{}:{folder}", container.name), format!("{}/", parent.to_string_lossy())];
+        match ide_docker::cli(endpoint, None, &args, COPY_TIMEOUT, None) {
+            Ok(_) => folders.push(folder),
+            Err(e) => tracing::warn!("cannot copy {folder} from {}: {}", container.name, e.message),
+        }
+    }
+    drop(container);
+    progress("Preparing the language server's interpreter");
+    let snapshot = Snapshot {
+        neutral_python: snapshots::neutral_python(cache, &probe.version),
+        image: image.clone(),
+        probe,
+        folders,
+    };
+    snapshots::write(&partial, &snapshot)?;
+    if dir.exists() {
+        std::fs::remove_dir_all(&dir)?;
+    }
+    std::fs::rename(&partial, &dir)?;
+    snapshots::make_current(target_dir, &image)?;
+    Ok(true)
+}
+
+/// Distinguishes probe containers.
+fn unique() -> String {
+    use std::sync::atomic::{AtomicU32, Ordering};
+    static COUNT: AtomicU32 = AtomicU32::new(0);
+    let secs = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).map_or(0, |d| d.as_secs());
+    format!("{:x}-{}-{}", secs & 0xff_ffff, std::process::id(), COUNT.fetch_add(1, Ordering::Relaxed))
+}

crates/ide-host/src/plugins/execution.rs

@@ -77,9 +77,22 @@ pub(super) fn validate_reply(reply: &ContentTabReply) -> Result<(), HostError> {
     Ok(())
 }
 
+/// Largest side of a plugin diff, in UTF-16 code units (earlier hosts allowed 1 MiB).
+pub(super) const MAX_DIFF_SIDE: usize = 8 << 20;
+
+fn diff_side(value: &str, side: &str) -> Result<(), HostError> {
+    if value.contains('\0') {
+        return Err(HostError::Invalid(format!("the {side} side of the diff contains NUL")));
+    }
+    if value.encode_utf16().count() > MAX_DIFF_SIDE {
+        return Err(HostError::Invalid(format!("diff too large: the {side} side is over {} MiB", MAX_DIFF_SIDE >> 20)));
+    }
+    Ok(())
+}
+
 pub(super) fn validate_diff(diff: &ide_plugin::ContentDiff) -> Result<(), HostError> {
-    body(&diff.left)?;
-    body(&diff.right)?;
+    diff_side(&diff.left, "left")?;
+    diff_side(&diff.right, "right")?;
     for value in [&diff.left_label, &diff.right_label].into_iter().flatten() {
         label(value, 128)?;
     }
@@ -571,3 +584,25 @@ impl PluginHost {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn diff(left: String, right: String) -> ide_plugin::ContentDiff {
+        ide_plugin::ContentDiff { left, right, left_label: None, right_label: None, title: None }
+    }
+
+    #[test]
+    fn diff_sides_up_to_the_limit_open_and_larger_ones_say_why() {
+        assert!(validate_diff(&diff("x".repeat(5 << 20), "y".repeat(MAX_DIFF_SIDE))).is_ok());
+        let err = validate_diff(&diff(String::new(), "y".repeat(MAX_DIFF_SIDE + 1))).unwrap_err();
+        assert!(
+            matches!(&err, HostError::Invalid(m) if m == "diff too large: the right side is over 8 MiB"),
+            "{err:?}"
+        );
+        assert!(
+            matches!(validate_diff(&diff("a\0".into(), String::new())), Err(HostError::Invalid(m)) if m.contains("NUL"))
+        );
+    }
+}

crates/ide-host/src/project.rs

@@ -174,6 +174,7 @@ impl Host {
                 let root = member.as_ref().unwrap_or(window_root);
                 ide_sdk::apply::server_launch_overrides(cfg, &effective);
                 ide_sdk::apply::configure_server(cfg, root, server_root, &effective);
+                crate::ops::sdk::container_python::configure_server(cfg, &data_dir, root, &effective);
                 if cfg.name == "jdtls" {
                     // A workspace member keeps its build model under its own key (Build Project).
                     let cache = match &member {
@@ -630,6 +631,7 @@ impl Host {
         if let Some(cmd) = post_start {
             self.environment.spawn_post_start(cmd, project.root.clone(), project.sink.clone());
         }
+        crate::ops::sdk::container_python::ensure(self, &project);
         Ok(project)
     }
 
@@ -1456,7 +1458,7 @@ fn content_root_watcher(
 ) -> Option<Watcher> {
     let (kotlin_bridge, phpstan) = (kotlin_bridge.cloned(), phpstan.cloned());
     let (index, documents, history, lsp) = (index.clone(), documents.clone(), history.clone(), lsp.clone());
-    let root = dir.to_path_buf();
+    let (root, events) = (dir.to_path_buf(), sink.clone());
     Watcher::start(
         dir,
         excludes.to_vec(),
@@ -1478,6 +1480,11 @@ fn content_root_watcher(
             }
             documents.on_disk_changed(&[&changed[..], &ignored].concat());
             record_external_changes(&history, &changed, &batch.removed);
+            // A member outside the project folder: its repository changes (commit, checkout,
+            // fetch, pull) reach the UI only through this watcher.
+            if batch.vcs.iter().any(|p| vcs_path_changed(p)) {
+                events.emit(IdeEvent::VcsChanged { root: root.clone().into() });
+            }
         }),
     )
     .map_err(|e| tracing::warn!("content root watcher {}: {e}", dir.display()))

crates/ide-host/src/trust.rs

@@ -289,6 +289,7 @@ impl crate::Host {
                 }
             }
             project.lsp.reconfigure().await;
+            crate::ops::sdk::container_python::ensure(self, &project);
             project.sink.emit(ide_core::IdeEvent::ProjectTrustChanged { root: project.root.clone().into(), trusted });
         }
         Ok(())

crates/ide-host/tests/container_python_real.rs

@@ -0,0 +1,174 @@
+//! A Compose run target as the Python interpreter, against a real daemon and the real
+//! basedpyright. Ignored by default: `OPENIDEA_DOCKER_TEST_DIR` names an empty folder the
+//! daemon can bind-mount (on this machine, or at the same path in a VM such as OrbStack's),
+//! `docker` with the Compose plugin and `basedpyright-langserver` must be on `PATH`, and
+//! this machine's Python must not have Django installed.
+#![cfg(unix)]
+
+use ide_core::IdeEvent;
+use ide_host::{Host, HostConfig, ops};
+use ide_run::{OutputChunk, RunConfig};
+use std::path::{Path, PathBuf};
+use std::process::Command;
+use std::sync::{Arc, Mutex};
+use std::time::{Duration, Instant};
+
+const WINDOW: &str = "main";
+type Events = Arc<Mutex<Vec<IdeEvent>>>;
+
+fn host(base: &Path, events: &Events) -> Arc<Host> {
+    Arc::new(Host::new(HostConfig {
+        config_dir: base.join("config"),
+        data_dir: base.join("data"),
+        local_data_dir: base.join("data"),
+        languages: Arc::new(ide_language::LanguageRegistry::load(None).unwrap()),
+        syntax: Arc::default(),
+        sink_for: Box::new({
+            let events = events.clone();
+            move |_| {
+                let events = events.clone();
+                Arc::new(move |e: IdeEvent| events.lock().unwrap().push(e))
+            }
+        }),
+        owner: |w| w,
+        runtime: tokio::runtime::Handle::current(),
+        project_environment: false,
+    }))
+}
+
+/// basedpyright's latest diagnostics of `path` once `done` accepts them.
+async fn diagnostics(events: &Events, path: &Path, timeout: Duration, done: impl Fn(&[String]) -> bool) -> Vec<String> {
+    let deadline = Instant::now() + timeout;
+    loop {
+        let latest = events.lock().unwrap().iter().rev().find_map(|e| match e {
+            IdeEvent::Diagnostics { path: p, items, source } if **p == *path && source.contains("basedpyright") => {
+                Some(items.iter().map(|d| d.message.clone()).collect::<Vec<_>>())
+            }
+            _ => None,
+        });
+        if let Some(messages) = &latest
+            && done(messages)
+        {
+            return messages.clone();
+        }
+        assert!(Instant::now() < deadline, "timed out; last diagnostics: {latest:?}");
+        tokio::time::sleep(Duration::from_millis(500)).await;
+    }
+}
+
+fn unresolved(messages: &[String]) -> bool {
+    messages.iter().any(|m| m.contains("\"django") && m.contains("could not be resolved"))
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+#[ignore = "requires a Docker daemon, basedpyright and OPENIDEA_DOCKER_TEST_DIR"]
+async fn compose_target_is_the_python_interpreter() {
+    let root = PathBuf::from(std::env::var("OPENIDEA_DOCKER_TEST_DIR").expect("OPENIDEA_DOCKER_TEST_DIR"));
+    let root = dunce::canonicalize(root).unwrap();
+    let files = [
+        ("compose.yaml", "services:\n  web:\n    build: .\n    volumes:\n      - .:/app\n    working_dir: /app\n"),
+        (
+            "Dockerfile",
+            "FROM python:3.12-slim\nCOPY requirements.txt /tmp/requirements.txt\n\
+             RUN pip install --no-cache-dir -r /tmp/requirements.txt\n",
+        ),
+        ("requirements.txt", "Django==5.1.3\n"),
+        (
+            "app/main.py",
+            "import django\nfrom django.http import HttpResponse\n\nprint(django.get_version(), HttpResponse)\n",
+        ),
+    ];
+    for (path, text) in files {
+        std::fs::create_dir_all(root.join(path).parent().unwrap()).unwrap();
+        std::fs::write(root.join(path), text).unwrap();
+    }
+    let main = root.join("app/main.py");
+    let state = tempfile::tempdir().unwrap();
+    let events: Events = Arc::default();
+    let host = host(state.path(), &events);
+    host.trust.decide(&root, true, false).unwrap();
+    host.open_project(WINDOW, &root).unwrap();
+    let set = |key: &str, value: serde_json::Value| {
+        ops::project::set_settings(
+            &host,
+            WINDOW,
+            ide_workspace::settings::SettingsScope::Project,
+            key,
+            &value.to_string(),
+        )
+        .unwrap();
+    };
+    set("runTargets", serde_json::json!([{ "kind": "compose", "id": "web", "name": "Compose web", "service": "web" }]));
+
+    // A local interpreter: Django is only in the image.
+    ops::doc::open(&host, WINDOW, main.clone()).await.unwrap();
+    let before = diagnostics(&events, &main, Duration::from_secs(120), unresolved).await;
+    eprintln!("local interpreter: {before:?}");
+
+    // The run target as the interpreter: a snapshot is taken in the background, then the
+    // server restarts with the copied site-packages as `extraPaths`.
+    set("languages.python.interpreter", serde_json::json!("target:web"));
+    let after = diagnostics(&events, &main, Duration::from_secs(900), |m| !unresolved(m)).await;
+    eprintln!("run target interpreter: {after:?}");
+    assert!(after.iter().all(|m| !m.contains("could not be resolved")), "{after:?}");
+
+    let info = ops::sdk::sdk_container_python(&host, WINDOW).unwrap().expect("a run target interpreter");
+    eprintln!("snapshot: version {:?}, image {:?}, folders {:?}", info.version, info.image, info.folders);
+    assert_eq!(info.name, "Compose web");
+    assert!(info.version.as_deref().is_some_and(|v| v.starts_with("3.12.")), "{info:?}");
+    assert!(info.packages.iter().any(|p| p.name == "Django" && p.version == "5.1.3"), "{:?}", info.packages);
+    let site = info.folders.iter().find(|f| f.0.ends_with("site-packages")).expect("site-packages copied");
+    assert!(site.0.join("django/__init__.py").is_file());
+    assert!(site.0.starts_with(state.path().join("data/container-python")), "{site:?}");
+    let servers = ops::lsp::lsp_servers(&host, WINDOW).unwrap();
+    eprintln!("servers: {:?}", servers.iter().map(|s| (&s.name, s.status)).collect::<Vec<_>>());
+
+    // Run: a Python configuration without its own target runs in the container.
+    let out = Arc::new(Mutex::new(String::new()));
+    let sink = out.clone();
+    let config = RunConfig {
+        id: "main".into(),
+        name: "main".into(),
+        kind: "python".into(),
+        command: "python3".into(),
+        args: vec!["app/main.py".into()],
+        cwd: None,
+        env: Default::default(),
+        detected: false,
+        is_test: false,
+        debug_adapter: None,
+        allow_parallel: false,
+        extras: Default::default(),
+    };
+    ops::run::start(
+        &host,
+        WINDOW,
+        config,
+        Arc::new(move |chunk| match chunk {
+            OutputChunk::Stdout { text } | OutputChunk::Stderr { text } | OutputChunk::System { text } => {
+                sink.lock().unwrap().push_str(&text)
+            }
+        }),
+    )
+    .await
+    .unwrap();
+    for _ in 0..1200 {
+        if out.lock().unwrap().contains("Process finished") {
+            break;
+        }
+        tokio::time::sleep(Duration::from_millis(100)).await;
+    }
+    let out = out.lock().unwrap().clone();
+    eprintln!("run output: {out}");
+    assert!(out.contains("5.1.3") && out.contains("exit code 0"), "{out}");
+
+    // Refresh takes a new snapshot of the same image; nothing is left running.
+    let refreshed = ops::sdk::sdk_container_python_refresh(&host, WINDOW).await.unwrap().unwrap();
+    assert_eq!(refreshed.image, info.image);
+    let probes = Command::new("docker")
+        .args(["ps", "--all", "--quiet", "--filter", "label=openidea.python-probe=true"])
+        .output()
+        .unwrap();
+    assert_eq!(String::from_utf8_lossy(&probes.stdout).trim(), "", "probe containers are removed");
+    Command::new("docker").args(["compose", "down", "--rmi", "local"]).current_dir(&root).status().unwrap();
+}

crates/ide-index/src/store.rs

@@ -599,6 +599,28 @@ impl Store {
         txn.commit().map_err(err)
     }
 
+    /// [`Self::apply`] for records already serialized (by the parse pool).
+    pub(crate) fn apply_raw(&self, puts: &[(String, Vec<u8>)], deletes: &[String], durable: bool) -> Result<()> {
+        self.ensure_db()?;
+        let db = self.db.read();
+        let mut txn = db.as_ref().expect("ensured").begin_write().map_err(err)?;
+        if !durable {
+            txn.set_durability(Durability::None).map_err(err)?;
+        }
+        {
+            let mut table = txn.open_table(FILES).map_err(err)?;
+            for (rel, bytes) in puts {
+                table.insert(rel.as_str(), bytes.as_slice()).map_err(err)?;
+            }
+            for rel in deletes {
+                table.remove(rel.as_str()).map_err(err)?;
+            }
+        }
+        // Any file change makes the columnar start-up snapshot stale.
+        let _ = std::fs::remove_file(&self.snapshot);
+        txn.commit().map_err(err)
+    }
+
     /// Reclaims free pages in the database file; `true` if anything was compacted.
     pub(crate) fn compact(&self) -> Result<bool> {
         self.ensure_db()?;

crates/ide-index/src/worker.rs

@@ -17,6 +17,8 @@ use std::time::{Duration, Instant, SystemTime};
 /// Files larger than this are listed but not parsed for symbols.
 pub const MAX_SYMBOL_FILE: u64 = 2 * 1024 * 1024;
 const CHUNK: usize = 512;
+/// Insert/persist batch of the initial scan's streaming pass.
+const SCAN_BATCH: usize = 2048;
 const PROGRESS_EVERY: Duration = Duration::from_millis(250);
 #[cfg(not(test))]
 const SNAPSHOT_DELAY: Duration = Duration::from_secs(2);
@@ -436,10 +438,13 @@ impl Shared {
         });
 
         let filter = self.filter();
+        let walk_started = Instant::now();
         let found = prewalked.unwrap_or_else(|| self.walk_roots(dirs));
+        let walk = walk_started.elapsed();
         if self.is_cancelled() {
             return self.end_scan(task);
         }
+        let classify_started = Instant::now();
         let seen: HashSet<&Path> = found.iter().map(|f| f.path.as_path()).collect();
         let (todo, stale): (Vec<&Found>, Vec<PathBuf>) = {
             let d = self.data.read();
@@ -452,6 +457,7 @@ impl Shared {
                 .collect();
             (todo, stale)
         };
+        let classify = classify_started.elapsed();
         if !stale.is_empty() {
             let mut d = self.data.write();
             for path in &stale {
@@ -462,33 +468,76 @@ impl Shared {
         self.persist(&[], &stale, false);
 
         let total = todo.len();
-        let mut done = 0usize;
-        let mut last_progress = Instant::now();
-        for chunk in todo.chunks(CHUNK) {
-            if self.is_cancelled() {
-                return self.end_scan(task);
-            }
-            self.index_files(chunk.iter().copied(), false);
-            done += chunk.len();
-            if last_progress.elapsed() >= PROGRESS_EVERY {
-                last_progress = Instant::now();
-                self.sink.emit(IdeEvent::Task {
-                    id: task,
-                    title: "Indexing".into(),
-                    message: Some(format!("{done} / {total} files")),
-                    fraction: Some(done as f32 / total.max(1) as f32),
-                    done: false,
-                    cancellable: false,
+        let mut laps = ChunkLaps::default();
+        {
+            // One streaming parallel pass: parse on the rayon pool without
+            // per-chunk joins (a straggler file at a join's tail idles every
+            // other core), while parsed files flow to this thread to be
+            // inserted and persisted in batches. `filter` moves into the
+            // parse thread; this thread keeps the outer one.
+            let filter = self.filter();
+            // Bounded: when inserting and persisting fall behind, the parse waits instead
+            // of holding the whole project's records (and their bytes) in the channel.
+            let (tx, rx) = std::sync::mpsc::sync_channel::<ParsedFile>(2 * SCAN_BATCH);
+            let cancelled = &self.cancelled;
+            let mut done = 0usize;
+            let mut last_progress = Instant::now();
+            let pass_started = Instant::now();
+            std::thread::scope(|scope| -> () {
+                scope.spawn(move || {
+                    todo.par_iter().for_each(|f| {
+                        if cancelled.load(Ordering::Relaxed) {
+                            return;
+                        }
+                        let Some(out) = self.parse_found(f, &filter, false) else { return };
+                        let _ = tx.send(out);
+                    });
+                    // `tx` drops here: the consumer's loop ends with the channel.
                 });
-            }
+                let mut batch: Vec<ParsedFile> = Vec::with_capacity(SCAN_BATCH);
+                for out in rx {
+                    if self.is_cancelled() {
+                        break;
+                    }
+                    batch.push(out);
+                    if batch.len() < SCAN_BATCH {
+                        continue;
+                    }
+                    done += batch.len();
+                    laps.add(self.publish(batch.drain(..)));
+                    if last_progress.elapsed() >= PROGRESS_EVERY {
+                        last_progress = Instant::now();
+                        self.sink.emit(IdeEvent::Task {
+                            id: task,
+                            title: "Indexing".into(),
+                            message: Some(format!("{done} / {total} files")),
+                            fraction: Some(done as f32 / total.max(1) as f32),
+                            done: false,
+                            cancellable: false,
+                        });
+                    }
+                }
+                if !batch.is_empty() && !self.is_cancelled() {
+                    done += batch.len();
+                    laps.add(self.publish(batch.drain(..)));
+                }
+            });
+            laps.extract = pass_started.elapsed();
         }
+        if self.is_cancelled() {
+            return self.end_scan(task);
+        }
+        let durable_started = Instant::now();
         self.persist(&[], &[], true);
+        let durable = durable_started.elapsed();
         if let Some(store) = &self.store {
             let recent: Vec<String> = self.recent.lock().iter().filter_map(|p| filter.store_key(p)).collect();
             let d = self.data.read();
+            let snapshot_started = Instant::now();
             if let Err(e) = store.save_snapshot(&d, &filter, guard) {
                 tracing::warn!("index snapshot: {e}");
             }
+            tracing::info!("index snapshot: written in {:?}", snapshot_started.elapsed());
             if let Err(e) = store.save_recent_file(&recent) {
                 tracing::warn!("index recent snapshot: {e}");
             }
@@ -506,54 +555,85 @@ impl Shared {
         self.emit_state();
         let d = self.data.read();
         tracing::info!(
-            "indexed {} files ({} parsed, {} symbols) in {:?}",
+            "indexed {} files ({} parsed, {} symbols) in {:?} (walk {:?}, classify {:?}, extract {:?}, insert {:?}, persist {:?}, durable {:?})",
             d.file_count,
             total,
             d.symbol_count,
-            started.elapsed()
+            started.elapsed(),
+            walk,
+            classify,
+            laps.extract,
+            laps.insert,
+            laps.persist,
+            durable
         );
     }
 
     /// Extracts records in parallel, then publishes them to memory and disk.
     /// `force` re-parses files whose content is unchanged (their language changed).
-    fn index_files<'a>(&self, files: impl Iterator<Item = &'a Found>, force: bool) {
+    fn index_files<'a>(&self, files: impl Iterator<Item = &'a Found>, force: bool) -> ChunkLaps {
+        let mut laps = ChunkLaps::default();
         let files: Vec<&Found> = files.collect();
         let filter = self.filter();
-        let extracted: Vec<(String, FileRecord, PathBuf)> = files
-            .par_iter()
-            .filter_map(|f| {
-                if self.is_cancelled() {
-                    return None;
-                }
-                let rel = filter.rel(&f.path)?;
-                let prev_hash = if force { None } else { self.data.read().get(&f.path).map(|e| e.hash) };
-                match self.extract(f, prev_hash) {
-                    Extracted::Unchanged => {
-                        // Same content, new mtime: keep the symbols, refresh metadata.
-                        let mut rec = self.data.read().record_of(&f.path)?;
-                        rec.mtime = f.mtime;
-                        rec.size = f.size;
-                        rec.ignored = f.ignored;
-                        Some((rel, rec, f.path.clone()))
-                    }
-                    Extracted::New(rec) => Some((rel, rec, f.path.clone())),
-                }
-            })
-            .collect();
+        let started = Instant::now();
+        let extracted: Vec<ParsedFile> = files.par_iter().filter_map(|f| self.parse_found(f, &filter, force)).collect();
+        laps.extract = started.elapsed();
         if extracted.is_empty() {
-            return;
+            return laps;
+        }
+        laps.add(self.publish(extracted.into_iter()));
+        laps
+    }
+
+    /// Reads and parses one file (parallel-safe), serializing its record for
+    /// the cache alongside the parse. `None` when the file is outside the
+    /// scope or the scan was cancelled.
+    fn parse_found(&self, f: &Found, filter: &std::sync::Arc<PathFilter>, force: bool) -> Option<ParsedFile> {
+        if self.is_cancelled() {
+            return None;
+        }
+        let rel = filter.rel(&f.path)?;
+        let prev_hash = if force { None } else { self.data.read().get(&f.path).map(|e| e.hash) };
+        let rec = match self.extract(f, prev_hash) {
+            Extracted::Unchanged => {
+                // Same content, new mtime: keep the symbols, refresh metadata.
+                let mut rec = self.data.read().record_of(&f.path)?;
+                rec.mtime = f.mtime;
+                rec.size = f.size;
+                rec.ignored = f.ignored;
+                rec
+            }
+            Extracted::New(rec) => rec,
+        };
+        let key = filter.store_key(&f.path);
+        let bytes = postcard::to_allocvec(&rec).ok();
+        Some(ParsedFile { rel, rec, key, bytes, path: f.path.clone() })
+    }
+
+    /// Inserts a parsed batch into the in-memory index and persists the records.
+    fn publish(&self, batch: impl Iterator<Item = ParsedFile>) -> ChunkLaps {
+        let mut laps = ChunkLaps::default();
+        let started = Instant::now();
+        let mut entries: Vec<(FileEntry, Vec<StoredSymbol>)> = Vec::new();
+        let mut puts: Vec<(String, Vec<u8>)> = Vec::new();
+        for out in batch {
+            let ParsedFile { rel, rec, key, bytes, path } = out;
+            if let (Some(key), Some(bytes)) = (key, bytes) {
+                puts.push((key, bytes));
+            }
+            entries.push(FileEntry::new(path, rel, rec));
         }
-        let puts: Vec<(String, FileRecord)> =
-            extracted.iter().filter_map(|(_, rec, path)| Some((filter.store_key(path)?, rec.clone()))).collect();
         {
-            let entries: Vec<(FileEntry, Vec<StoredSymbol>)> =
-                extracted.into_iter().map(|(rel, rec, path)| FileEntry::new(path, rel, rec)).collect();
             let mut d = self.data.write();
             for (e, symbols) in entries {
                 d.insert(e, symbols);
             }
         }
-        self.persist(&puts, &[], false);
+        laps.insert = started.elapsed();
+        let started = Instant::now();
+        self.persist_raw(&puts, &[], false);
+        laps.persist = started.elapsed();
+        laps
     }
 
     fn schedule_snapshot(&self) {
@@ -594,6 +674,15 @@ impl Shared {
         }
     }
 
+    /// [`Self::persist`] for records already serialized by the parse pool.
+    fn persist_raw(&self, puts: &[(String, Vec<u8>)], deletes: &[String], durable: bool) {
+        if let Some(store) = &self.store
+            && let Err(e) = store.apply_raw(puts, deletes, durable)
+        {
+            tracing::warn!("index cache write failed: {e}");
+        }
+    }
+
     fn extract(&self, f: &Found, prev_hash: Option<[u8; 32]>) -> Extracted {
         let mut rec = FileRecord { mtime: f.mtime, size: f.size, ignored: f.ignored, ..Default::default() };
         if f.ignored || f.size > MAX_SYMBOL_FILE {
@@ -793,6 +882,33 @@ enum Extracted {
     New(FileRecord),
 }
 
+/// Wall-time laps of one `index_files` chunk, accumulated by the scan.
+#[derive(Default)]
+struct ChunkLaps {
+    extract: Duration,
+    insert: Duration,
+    persist: Duration,
+}
+
+impl ChunkLaps {
+    fn add(&mut self, other: ChunkLaps) {
+        self.extract += other.extract;
+        self.insert += other.insert;
+        self.persist += other.persist;
+    }
+}
+
+/// One file parsed off the index thread: its record ready to publish, already
+/// serialized for the cache (in parallel with the parse).
+struct ParsedFile {
+    rel: String,
+    rec: FileRecord,
+    /// Cache key and postcard bytes; `None` when outside the persisted root.
+    key: Option<String>,
+    bytes: Option<Vec<u8>>,
+    path: PathBuf,
+}
+
 #[cfg(test)]
 mod tests {
     use crate::data::safe_rel;

crates/ide-language/src/lib.rs

@@ -28,6 +28,7 @@ pub use syntax::{
     VueComponentImport, VueRefAccess, VueRefElement, WebReference, WebReferenceKind, merge_visibility,
     set_external_syntax, shift_pos, shift_range,
 };
+pub use syntax::{MethodBody, PythonClassFacts, PythonFacts, PythonMethodFacts};
 
 /// Parsed form of `languages/<id>.toml`. Backend-only; the UI gets [`LanguageInfo`].
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -198,6 +199,10 @@ pub struct LanguageServerConfig {
     /// it parses a document.
     #[serde(default)]
     pub resync_on_configuration: bool,
+    /// Set by the settings hook: what the user sees as the server when another program serves
+    /// in its place (TypeScript 7's own `tsc --lsp` for vtsls).
+    #[serde(skip)]
+    pub display_name: Option<String>,
     /// Set on plugin languages: start exactly this approved program.
     #[serde(skip)]
     pub pinned: Option<ProgramPin>,

crates/ide-language/src/syntax/inheritance.rs

@@ -43,7 +43,7 @@ fn extract(tree: &Tree, text: &str) -> Vec<ClassBases> {
         // Selection-range start of the class: its name identifier (`class Foo`
         // -> `Foo`), matching `outline.rs` and the gutter marker candidates.
         let range = idx.range(name_node.start_byte(), name_node.end_byte());
-        let bases = node.child_by_field_name("superclasses").map(|args| base_names(args, text)).unwrap_or_default();
+        let bases = class_base_names(node, text);
         out.push(ClassBases { name, line: range.start.line, col: range.start.col, bases });
     });
     out
@@ -67,6 +67,11 @@ fn visit(cursor: &mut tree_sitter::TreeCursor, f: &mut impl FnMut(Node)) {
     }
 }
 
+/// The bare base names a `class_definition` node writes (keyword arguments left out).
+pub(super) fn class_base_names(node: Node, text: &str) -> Vec<String> {
+    node.child_by_field_name("superclasses").map(|args| base_names(args, text)).unwrap_or_default()
+}
+
 fn base_names(args: Node, text: &str) -> Vec<String> {
     let mut out = Vec::new();
     let mut cursor = args.walk();

crates/ide-language/src/syntax/mod.rs

@@ -10,6 +10,7 @@ mod inheritance;
 pub(crate) mod lines;
 mod literals;
 mod outline;
+mod python_facts;
 mod rst;
 mod selection;
 mod sfc;
@@ -27,6 +28,7 @@ pub use inheritance::ClassBases;
 pub use lines::{shift_pos, shift_range};
 pub use literals::{Literal, LiteralKind, SpellingKind, SpellingRegion};
 pub use outline::merge_visibility;
+pub use python_facts::{MethodBody, PythonClassFacts, PythonFacts, PythonMethodFacts};
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::sync::OnceLock;

crates/ide-language/src/syntax/python_facts.rs

@@ -0,0 +1,438 @@
+//! Python class facts the inheritance inspections need: base names as written, parameter
+//! lists, decorator semantics and what a method body does. They come from the syntax tree in
+//! one pass, so the frontend reasons about the inheritance graph without parsing source text.
+//!
+//! Deliberately small: a fact exists here only when a check can decide it without guessing.
+
+use super::lines::LineIndex;
+use crate::{LanguageId, Syntax};
+use serde::{Deserialize, Serialize};
+use specta::Type;
+use tree_sitter::{Node, Tree};
+
+/// One Python module's classes, in source order.
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PythonFacts {
+    pub classes: Vec<PythonClassFacts>,
+}
+
+/// A class definition and the methods it declares.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PythonClassFacts {
+    pub name: String,
+    /// The class name identifier (selection range).
+    pub selection: crate::Range,
+    /// Base names as written, a qualified name reduced to its last segment.
+    pub bases: Vec<String>,
+    pub methods: Vec<PythonMethodFacts>,
+}
+
+/// A method definition the inspections can reason about.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase")]
+pub struct PythonMethodFacts {
+    pub name: String,
+    /// The method name identifier (selection range).
+    pub selection: crate::Range,
+    /// Parameter names in order; `None` for a form whose forwarding cannot be compared
+    /// (`*args`, `**kwargs`, keyword-only, positional-only).
+    pub params: Option<Vec<String>>,
+    /// Decorated with `abstractmethod` (`abc.abstractmethod` included).
+    pub abstract_method: bool,
+    /// Decorated with `override` from `typing` / `typing_extensions`.
+    pub override_decorated: bool,
+    pub body: MethodBody,
+}
+
+/// What a method body does, for the shapes a check can decide without guessing.
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]
+#[serde(rename_all = "camelCase", tag = "kind")]
+pub enum MethodBody {
+    /// `pass`, `...`, a docstring, or nothing at all.
+    Empty,
+    /// Exactly one `super().name(args)` call, optionally `return`ed.
+    SuperCall { returns: bool, target: String, args: Vec<String> },
+    /// Anything else.
+    Other,
+}
+
+impl Syntax {
+    /// The classes of a Python `text` with the facts the inheritance checks need.
+    /// Every other language returns an empty result.
+    pub fn python_facts(&self, lang: &LanguageId, text: &str) -> PythonFacts {
+        self.analyze(lang, text, |g, tree, text| (g.spec.name == "python").then(|| extract(tree, text)))
+            .unwrap_or_default()
+    }
+}
+
+fn extract(tree: &Tree, text: &str) -> PythonFacts {
+    let idx = LineIndex::new(text);
+    let imports = ImportBindings::collect(tree, text);
+    let mut classes = Vec::new();
+    let mut cursor = tree.walk();
+    visit(&mut cursor, &mut |node| {
+        if node.kind() != "class_definition" {
+            return;
+        }
+        let Some(name_node) = node.child_by_field_name("name") else { return };
+        let name = text_of(name_node, text);
+        if name.is_empty() {
+            return;
+        }
+        classes.push(PythonClassFacts {
+            name,
+            selection: idx.range(name_node.start_byte(), name_node.end_byte()),
+            bases: super::inheritance::class_base_names(node, text),
+            methods: methods_of(node, text, &idx, &imports),
+        });
+    });
+    PythonFacts { classes }
+}
+
+/// The methods declared directly in `class`.
+fn methods_of(class: Node, text: &str, idx: &LineIndex, imports: &ImportBindings) -> Vec<PythonMethodFacts> {
+    let Some(body) = class.child_by_field_name("body") else { return Vec::new() };
+    let mut out = Vec::new();
+    let mut cursor = body.walk();
+    for member in body.named_children(&mut cursor) {
+        // A decorated method is a `decorated_definition` wrapping the `function_definition`.
+        let method = match member.kind() {
+            "function_definition" => member,
+            "decorated_definition" => match member.child_by_field_name("definition") {
+                Some(inner) if inner.kind() == "function_definition" => inner,
+                _ => continue,
+            },
+            _ => continue,
+        };
+        let Some(name_node) = method.child_by_field_name("name") else { continue };
+        let name = text_of(name_node, text);
+        if name.is_empty() {
+            continue;
+        }
+        let decorators = decorators_of(method, text);
+        out.push(PythonMethodFacts {
+            name,
+            selection: idx.range(name_node.start_byte(), name_node.end_byte()),
+            params: parameters_of(method, text),
+            abstract_method: decorators.iter().any(|d| last_segment(d) == "abstractmethod"),
+            override_decorated: decorators.iter().any(|d| imports.is_typing_override(d)),
+            body: body_of(method, text),
+        });
+    }
+    out
+}
+
+/// The parameter names of a `function_definition`, or `None` when the signature contains a
+/// form whose forwarding cannot be compared without guessing.
+fn parameters_of(function: Node, text: &str) -> Option<Vec<String>> {
+    let params = function.child_by_field_name("parameters")?;
+    let mut names = Vec::new();
+    let mut cursor = params.walk();
+    for param in params.named_children(&mut cursor) {
+        let name = match param.kind() {
+            "identifier" => text_of(param, text),
+            "typed_parameter" | "default_parameter" | "typed_default_parameter" => {
+                let named = param
+                    .child_by_field_name("name")
+                    .or_else(|| param.child_by_field_name("pattern"))
+                    .or_else(|| param.named_child(0))?;
+                if named.kind() != "identifier" {
+                    return None;
+                }
+                text_of(named, text)
+            }
+            // `*args`, `**kwargs`, `/`, `*`: the call form cannot be compared textually.
+            _ => return None,
+        };
+        if !name.is_empty() {
+            names.push(name);
+        }
+    }
+    Some(names)
+}
+
+/// A `function_definition`'s body, classified into the shapes a check can decide.
+fn body_of(function: Node, text: &str) -> MethodBody {
+    let Some(body) = function.child_by_field_name("body") else { return MethodBody::Empty };
+    // A docstring is not a statement the checks care about.
+    let statements: Vec<Node> = statements_of(body).into_iter().filter(|s| !is_string(*s)).collect();
+    if statements.is_empty() || statements.iter().all(|s| is_noop(*s)) {
+        return MethodBody::Empty;
+    }
+    let [only] = statements.as_slice() else { return MethodBody::Other };
+    let call = match only.kind() {
+        "expression_statement" => (only.named_child(0), false),
+        "return_statement" => (only.named_child(0), true),
+        _ => (None, false),
+    };
+    match call {
+        (Some(call), returns) if is_super_call(call, text) => {
+            let target = call
+                .child_by_field_name("function")
+                .and_then(|f| f.child_by_field_name("attribute"))
+                .map(|a| text_of(a, text))
+                .unwrap_or_default();
+            let args = call
+                .child_by_field_name("arguments")
+                .map(|args| {
+                    let mut cursor = args.walk();
+                    args.named_children(&mut cursor).map(|a| text_of(a, text)).collect()
+                })
+                .unwrap_or_default();
+            MethodBody::SuperCall { returns, target, args }
+        }
+        _ => MethodBody::Other,
+    }
+}
+
+/// Whether `node` is a `super().name(...)` call.
+fn is_super_call(node: Node, text: &str) -> bool {
+    if node.kind() != "call" {
+        return false;
+    }
+    let Some(function) = node.child_by_field_name("function") else { return false };
+    if function.kind() != "attribute" {
+        return false;
+    }
+    function.child_by_field_name("object").is_some_and(|object| {
+        object.kind() == "call"
+            && object
+                .child_by_field_name("function")
+                .is_some_and(|f| f.kind() == "identifier" && text_of(f, text) == "super")
+    })
+}
+
+/// Whether `statement` is `pass` or a bare `...`.
+fn is_noop(statement: Node) -> bool {
+    match statement.kind() {
+        "pass_statement" => true,
+        "expression_statement" => statement.named_child(0).is_some_and(|child| child.kind() == "ellipsis"),
+        _ => false,
+    }
+}
+
+/// A string expression statement: a docstring.
+fn is_string(statement: Node) -> bool {
+    statement.kind() == "expression_statement" && statement.named_child(0).is_some_and(|child| child.kind() == "string")
+}
+
+/// The statements of a `block`, comments excluded.
+fn statements_of(block: Node) -> Vec<Node> {
+    let mut cursor = block.walk();
+    block.named_children(&mut cursor).filter(|child| child.kind() != "comment").collect()
+}
+
+/// The decorators written on a definition, without the `@` or the call arguments.
+fn decorators_of(definition: Node, text: &str) -> Vec<String> {
+    let Some(parent) = definition.parent() else { return Vec::new() };
+    if parent.kind() != "decorated_definition" {
+        return Vec::new();
+    }
+    let mut out = Vec::new();
+    let mut cursor = parent.walk();
+    for decorator in parent.named_children(&mut cursor) {
+        if decorator.kind() != "decorator" {
+            continue;
+        }
+        let Some(inner) = decorator.named_child(0) else { continue };
+        let target =
+            if inner.kind() == "call" { inner.child_by_field_name("function").unwrap_or(inner) } else { inner };
+        let name = text_of(target, text).trim().to_owned();
+        if !name.is_empty() {
+            out.push(name);
+        }
+    }
+    out
+}
+
+/// The last segment of a dotted name (`typing.override` -> `override`).
+fn last_segment(name: &str) -> &str {
+    name.rsplit('.').next().unwrap_or(name)
+}
+
+fn text_of(node: Node, text: &str) -> String {
+    text.get(node.byte_range()).unwrap_or_default().to_owned()
+}
+
+/// The module-level `from ... import ...` bindings, so `override` can be told apart from a
+/// same-named decorator of another library.
+struct ImportBindings {
+    /// (local name, module, exported name)
+    bindings: Vec<(String, String, String)>,
+}
+
+impl ImportBindings {
+    fn collect(tree: &Tree, text: &str) -> Self {
+        let mut bindings = Vec::new();
+        let mut cursor = tree.walk();
+        visit(&mut cursor, &mut |node| {
+            if node.kind() != "import_from_statement" {
+                return;
+            }
+            let Some(module) = node.child_by_field_name("module_name") else { return };
+            let module = text_of(module, text);
+            let mut names = node.walk();
+            for name in node.children_by_field_name("name", &mut names) {
+                let (local, exported) = match name.kind() {
+                    "aliased_import" => (
+                        name.child_by_field_name("alias").map(|n| text_of(n, text)),
+                        name.child_by_field_name("name").map(|n| text_of(n, text)),
+                    ),
+                    _ => {
+                        let written = text_of(name, text);
+                        (Some(written.clone()), Some(written))
+                    }
+                };
+                if let (Some(local), Some(exported)) = (local, exported) {
+                    bindings.push((local, module.clone(), exported));
+                }
+            }
+        });
+        Self { bindings }
+    }
+
+    /// Whether `decorator` names `override` from `typing` / `typing_extensions`.
+    fn is_typing_override(&self, decorator: &str) -> bool {
+        const MODULES: [&str; 2] = ["typing", "typing_extensions"];
+        let segments: Vec<&str> = decorator.split('.').filter(|s| !s.is_empty()).collect();
+        match segments.as_slice() {
+            // `@typing.override`, or `@t.override` after `import typing as t`.
+            [prefix, "override"] => {
+                MODULES.contains(prefix)
+                    || self
+                        .bindings
+                        .iter()
+                        .find(|(local, _, _)| local == prefix)
+                        .is_some_and(|(_, module, _)| MODULES.contains(&module.as_str()))
+            }
+            // `@override`, or `@ov` after `from typing import override as ov`.
+            [local] => match self.bindings.iter().find(|(bound, _, _)| bound == local) {
+                Some((_, module, exported)) => exported == "override" && MODULES.contains(&module.as_str()),
+                // Nothing contradicts a bare `@override`: the usual `from typing import *`.
+                None => *local == "override",
+            },
+            _ => false,
+        }
+    }
+}
+
+/// Depth-first pre-order traversal of all descendants of `cursor`'s node.
+fn visit(cursor: &mut tree_sitter::TreeCursor, f: &mut impl FnMut(Node)) {
+    loop {
+        f(cursor.node());
+        if cursor.goto_first_child() {
+            continue;
+        }
+        loop {
+            if cursor.goto_next_sibling() {
+                break;
+            }
+            if !cursor.goto_parent() {
+                return;
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    static SYNTAX: std::sync::OnceLock<Syntax> = std::sync::OnceLock::new();
+
+    fn facts(src: &str) -> PythonFacts {
+        SYNTAX.get_or_init(Syntax::new).python_facts(&LanguageId::new("python"), src)
+    }
+
+    fn method<'a>(facts: &'a PythonFacts, class: &str, method: &str) -> &'a PythonMethodFacts {
+        facts
+            .classes
+            .iter()
+            .find(|c| c.name == class)
+            .and_then(|c| c.methods.iter().find(|m| m.name == method))
+            .expect("method not found")
+    }
+
+    #[test]
+    fn classes_carry_bases_and_methods() {
+        let f = facts(
+            "class Base(ABC):\n    pass\n\nclass Child(Base, pkg.Mixin):\n    def run(self, x=1):\n        pass\n",
+        );
+        assert_eq!(f.classes.len(), 2);
+        assert_eq!(f.classes[0].name, "Base");
+        assert_eq!(f.classes[0].bases, ["ABC"]);
+        assert_eq!(f.classes[1].bases, ["Base", "Mixin"]);
+        assert_eq!(f.classes[1].methods.len(), 1);
+        assert_eq!(f.classes[1].selection.start.line, 3);
+        assert_eq!(f.classes[1].selection.start.col, 6);
+    }
+
+    #[test]
+    fn parameters_are_names_in_order_and_none_for_splats() {
+        let f = facts(
+            "class C:\n    def a(self, x: int, y=2):\n        pass\n\n    def b(self, *args):\n        pass\n\n    def c(self, *, x):\n        pass\n",
+        );
+        assert_eq!(
+            method(&f, "C", "a").params.as_deref(),
+            Some(["self".to_string(), "x".to_string(), "y".to_string()].as_slice())
+        );
+        assert_eq!(method(&f, "C", "b").params, None);
+        assert_eq!(method(&f, "C", "c").params, None);
+    }
+
+    #[test]
+    fn body_shapes_are_classified() {
+        let f = facts(
+            "class C:\n    def noop(self):\n        pass\n\n    def dots(self):\n        ...\n\n    def doc(self):\n        \"\"\"text\"\"\"\n\n    def forward(self, x):\n        return super().run(x)\n\n    def call(self):\n        super().run()\n\n    def other(self):\n        return 1\n",
+        );
+        assert_eq!(method(&f, "C", "noop").body, MethodBody::Empty);
+        assert_eq!(method(&f, "C", "dots").body, MethodBody::Empty);
+        assert_eq!(method(&f, "C", "doc").body, MethodBody::Empty);
+        assert_eq!(
+            method(&f, "C", "forward").body,
+            MethodBody::SuperCall { returns: true, target: "run".into(), args: vec!["x".into()] }
+        );
+        assert_eq!(
+            method(&f, "C", "call").body,
+            MethodBody::SuperCall { returns: false, target: "run".into(), args: vec![] }
+        );
+        assert_eq!(method(&f, "C", "other").body, MethodBody::Other);
+    }
+
+    #[test]
+    fn decorators_are_their_names_and_semantics() {
+        let f = facts(
+            "from abc import abstractmethod\nfrom typing import override\n\nclass C:\n    @abstractmethod\n    def a(self):\n        pass\n\n    @override\n    def b(self):\n        pass\n\n    @functools.cache\n    def c(self):\n        pass\n",
+        );
+        assert!(method(&f, "C", "a").abstract_method);
+        assert!(!method(&f, "C", "a").override_decorated);
+        assert!(method(&f, "C", "b").override_decorated);
+        assert!(!method(&f, "C", "c").override_decorated);
+    }
+
+    #[test]
+    fn override_of_another_library_is_not_typing_override() {
+        let f = facts("from mylib import override\n\nclass C:\n    @override\n    def a(self):\n        pass\n");
+        assert!(!method(&f, "C", "a").override_decorated);
+    }
+
+    #[test]
+    fn aliased_override_and_qualified_forms_are_recognised() {
+        let f = facts(
+            "from typing import override as ov\n\nclass C:\n    @ov\n    def a(self):\n        pass\n\nclass D:\n    @typing_extensions.override\n    def b(self):\n        pass\n",
+        );
+        assert!(method(&f, "C", "a").override_decorated);
+        assert!(method(&f, "D", "b").override_decorated);
+    }
+
+    #[test]
+    fn nested_classes_and_other_languages() {
+        let f = facts("class Outer:\n    class Inner:\n        def m(self):\n            pass\n");
+        let names: Vec<&str> = f.classes.iter().map(|c| c.name.as_str()).collect();
+        assert_eq!(names, ["Outer", "Inner"]);
+        let other = SYNTAX.get_or_init(Syntax::new).python_facts(&LanguageId::new("rust"), "class C {}");
+        assert_eq!(other.classes.len(), 0);
+    }
+}

crates/ide-lsp/src/lib.rs

@@ -3097,6 +3097,21 @@ impl LspManager {
         Ok(CallHierarchy { items: out, incomplete })
     }
 
+    /// The type at `pos` as the server's type hierarchy names it (with its `detail`, the
+    /// package for Java); `None` when there is no type there.
+    pub async fn prepare_type_hierarchy(&self, doc: DocId, pos: Pos) -> IdeResult<Option<HierarchyItem>> {
+        let (snap, targets) = self.doc_targets(doc, "type hierarchy", |c| c.has("typeHierarchyProvider")).await?;
+        let t = &targets[0];
+        let items: Option<Vec<serde_json::Value>> =
+            self.call(t, "textDocument/prepareTypeHierarchy", snap.pos_params(t, pos), None, DEFAULT_TIMEOUT).await?;
+        let conv = self.conv(t.enc());
+        Ok(items
+            .unwrap_or_default()
+            .iter()
+            .filter_map(convert::type_item_from_json)
+            .find_map(|i| convert::type_item(&conv, &i)))
+    }
+
     pub async fn type_hierarchy(
         &self,
         doc: DocId,
@@ -3855,6 +3870,7 @@ impl LspManager {
                 languages: s.languages(),
                 status: s.status(),
                 pid: s.running().and_then(|r| r.peer.pid()),
+                label: s.display_name(),
             })
             .collect()
     }

crates/ide-lsp/src/server.rs

@@ -213,6 +213,11 @@ impl Server {
         config
     }
 
+    /// The configured server's display name for the current (or last) instance.
+    pub fn display_name(&self) -> Option<String> {
+        self.effective.lock().as_ref().and_then(|c| c.display_name.clone())
+    }
+
     pub fn set_effective_config(&self, generation: u64, config: LanguageServerConfig) {
         let st = self.state.lock();
         if st.generation == generation && matches!(st.conn, Conn::Starting | Conn::Ready(_)) {
@@ -507,7 +512,13 @@ impl Server {
             return;
         }
         *cur = (status, message.clone());
-        st.events.push_back(IdeEvent::LanguageServer { server: self.id, name: self.name.clone(), status, message });
+        st.events.push_back(IdeEvent::LanguageServer {
+            server: self.id,
+            name: self.name.clone(),
+            label: self.display_name(),
+            status,
+            message,
+        });
     }
 
     fn queue_cleanup(&self, st: &mut State) {

crates/ide-lsp/src/types.rs

@@ -341,6 +341,10 @@ pub struct ServerInfo {
     pub status: ServerStatus,
     /// OS process of the running instance (for memory attribution).
     pub pid: Option<u32>,
+    /// What the user sees as the server when another program serves in its place.
+    #[serde(default)]
+    #[specta(optional)]
+    pub label: Option<String>,
 }
 
 /// Read-only contents a language server provides for a non-`file:` URI

crates/ide-lsp/tests/mock_server.rs

@@ -268,6 +268,7 @@ fn server_cfg(name: &str) -> LanguageServerConfig {
         tsserver_project: false,
         tsserver_project_extras: Default::default(),
         resync_on_configuration: false,
+        display_name: None,
         pinned: None,
     }
 }

crates/ide-lsp/tests/real_servers.rs

@@ -426,6 +426,7 @@ async fn missing_binary_is_reported_with_install_hint() {
         tsserver_project: false,
         tsserver_project_extras: Default::default(),
         resync_on_configuration: false,
+        display_name: None,
         pinned: None,
     };
     let (mgr, events) = manager(dir.path(), LanguageRegistry::from_configs(vec![lang("nope", "nope", server)]));
@@ -698,6 +699,7 @@ async fn typescript_language_server_end_to_end() {
         tsserver_project: false,
         tsserver_project_extras: Default::default(),
         resync_on_configuration: false,
+        display_name: None,
         pinned: None,
     };
     let (mgr, events) = manager(&root, LanguageRegistry::from_configs(vec![lang("typescript", "ts", server)]));
@@ -750,6 +752,7 @@ fn npm_server(tools: &Path, name: &str, bin: &str, init: Option<serde_json::Valu
         tsserver_project: false,
         tsserver_project_extras: Default::default(),
         resync_on_configuration: false,
+        display_name: None,
         pinned: None,
     }
 }

crates/ide-plugin/tests/fixtures/api14/dist/plugin.wasm.sources

@@ -1 +1 @@
-e616b87b24371581ad648f9c7072259de7732d122b5887b488f7bd480ebd69c2
+0b77e7a414ec3b0dd1f41e5658b981f059dd842743dbe2f06e5d428f5b9570f9

crates/ide-plugin/tests/fixtures/commit/dist/plugin.wasm.sources

@@ -1 +1 @@
-75eeecc467bff141bda14f1f080633348af348f7259e793be81e6548d2008669
+6f7d6527837c8e5c86c377479cceef5116decd61666b28f36dd11332e36e9934

crates/ide-plugin/tests/fixtures/data-tools/dist/plugin.wasm.sources

@@ -1 +1 @@
-4aaf7754e895f022d34dad05bd2b8018e3a61ba18771b8c95d9f070cb212530c
+c1ac86a5b4d45b55013e6e00dcb83deda33b759ecc366c3fdf57739bdd22cbff

crates/ide-plugin/tests/fixtures/detail-views/dist/plugin.wasm.sources

@@ -1 +1 @@
-e573144879a7caa0975e17b233476eb317ff54bef23fd8fa64280d3649bad700
+e4d8d8f5f5849b912b2c0ebee6b91d60796c3070929d7698323e8ce4f200a38a

crates/ide-plugin/tests/fixtures/diagnostics/dist/plugin.wasm.sources

@@ -1 +1 @@
-36dd40ef751a617f1ad59491312889c12481b05666e580f21f7c2552df76edbc
+e2e2fc44ad9cae9cf26a5bf706768d3786502f23db6994dc29695deb249ed73f

crates/ide-plugin/tests/fixtures/endpoints/dist/plugin.wasm.sources

@@ -1 +1 @@
-724ed3bbd828e4fc1925c1b555bdaec9268633cb587806a661f8838e5a540545
+61e1f0c43bbfddc35dcf40685169eb273777ddca13da534626e1699b47e8eac3

crates/ide-plugin/tests/fixtures/execution/dist/plugin.wasm.sources

@@ -1 +1 @@
-1a3685234f1b3b0957184c44c603c0eefe7e3084b88d0df32da268b29292ee92
+2ea1c1693db8638db996c9c47597f0c1635ef0a9c7dfb33685c515b7af95e6a6

crates/ide-plugin/tests/fixtures/ext-owner/dist/plugin.wasm.sources

@@ -1 +1 @@
-4283de821d69a18438f58062e4bc28b63ba5025cc5f9fa51f21ff475b677a6a5
+3c788f6092b229484a5d94fd0e6f4651afc88dd0ab1b22b067d84614a6a0c85e

crates/ide-plugin/tests/fixtures/file-templates/dist/plugin.wasm.sources

@@ -1 +1 @@
-0f25487b8e488e5ec01fabd2951bdb03d80bc26e4e9aa508394a7f9cd09d1759
+18273599cc459833d6a30185a5f0ba127cdb4e22bc054a973571e530eb3a85ca

crates/ide-plugin/tests/fixtures/files-events/dist/plugin.wasm.sources

@@ -1 +1 @@
-80f9dc28e4f168dd22ccee1c53e1f6b08c446622eb10f07de29be5fc45e9fb1c
+c9fafba362fa0745d7ee1685efe5582d432510003c04c98100eddd557bd1e2cf

crates/ide-plugin/tests/fixtures/grouped-views/dist/plugin.wasm.sources

@@ -1 +1 @@
-5355cb4ef373eba3c54806eb00294fcd5fccb3cf05dae3e1c2a4ad45ab958f03
+4121009913709edeca8c5cb52d88dfcc2b16867bc06859768f73c17cf9c456a2

crates/ide-plugin/tests/fixtures/hello/dist/plugin.wasm.sources

@@ -1 +1 @@
-fc75ede42e6db7619fa28fc8999f091d39e3c1ed401356db3a3f07de54287c99
+b55bd202a06f5643c4f70abb6fb473fbe53af657f4e21a6d13581a23a726e085

crates/ide-plugin/tests/fixtures/hover/dist/plugin.wasm.sources

@@ -1 +1 @@
-8793601496f1727cf912e4cdf86ec48fc340a17585098e98dee52a125cb8a16d
+11a12228df67f9b94bd52375b5dddb2d955f7e5f88d7f9ea0a430b1db128f6ca

crates/ide-plugin/tests/fixtures/indexer/dist/plugin.wasm.sources

@@ -1 +1 @@
-fb2db14a645cad42941d20a25a3ff87ca6fdee635fdb40953383ff30ce16af8a
+553ce6c57052f8ff2ea2526e88762d5a0aee2489cda192fc7ab708766078ccf7

crates/ide-plugin/tests/fixtures/inlay-hints/dist/plugin.wasm.sources

@@ -1 +1 @@
-fc66b3b56a1ab1c9d547e3efe6bb4693dca908bb18be8b8ebd26f2fb41e4436c
+7b43f8a2a06d7b2952f8d46727a4cce524fb2bdecee1035dad9c767261d276d0

crates/ide-plugin/tests/fixtures/jobs/dist/plugin.wasm.sources

@@ -1 +1 @@
-c76830df9dee3caba932ffaddaabce88ac7ef23b3957b3e8e570b4939dd58d9d
+e994c69fda5eef94ae85d6dac5aec3d04fb6811c35c446c9d33236a449bd1c6c

crates/ide-plugin/tests/fixtures/language-features/dist/plugin.wasm.sources

@@ -1 +1 @@
-3a41a06d54939a9e85fcf6b0bf15b336f928a3caf66576bd2da62c5b8b177c1d
+c37f6a7ea9018ca636d0fd486a9d91cd397158615410de9b837ca9b8f9f593b7

crates/ide-plugin/tests/fixtures/misbehave/dist/plugin.wasm.sources

@@ -1 +1 @@
-f30a8c0a7893519872628c001314efd567f87f4dfaf718a737ea3631b55881b0
+1b298dfa5c1f2163d609ef0ccc3d42fafe78e69326002effe53abc4b82974749

crates/ide-plugin/tests/fixtures/path-events/dist/plugin.wasm.sources

@@ -1 +1 @@
-cb65533984ffd8684c9e9f5ddeef92a8f387735c12310b25282ee7bbf2d73cd7
+1e11a95e0909d18308d21a9a8448f8b2e427d240d5d8cd13d8ddbe6ba5009237

crates/ide-plugin/tests/fixtures/private-dir/dist/plugin.wasm.sources

@@ -1 +1 @@
-d11f9cb1130f3f3aaa89514bf47ec8ece9b2ca0edf1d82c11f80b262325f16be
+d5cd77130cc97cffdbc742f04e3e1196f14160107b636806c6ef3c9b40724e84

crates/ide-plugin/tests/fixtures/semantic-tokens/dist/plugin.wasm.sources

@@ -1 +1 @@
-48ea4414469ebd70a89da8a5df7b7bddc4d32f5c50f1759ee3cea14558073c92
+a0f74430b0a7d9ff48524d7aae4f8a0bd0fc60511e2a951dde9991b9bf7d15a9

crates/ide-plugin/tests/fixtures/settings-pages/dist/plugin.wasm.sources

@@ -1 +1 @@
-0c02303182be04ed3776fb532fd8b72e6057aa0fdb92b7d235000146fef4120e
+65508f6e25bd0efc85820ae7d0f9037b58c778fa61e8498c5b9a5055cc38f6fc

crates/ide-plugin/tests/fixtures/storage/dist/plugin.wasm.sources

@@ -1 +1 @@
-8162a70e848172663463119e6357984a73e54bc71a99b2845621d0733cf9333e
+c86ed41d68c132f72eb8b5794f31b975492e5ad42e41b7823d1bf28ba118a262

crates/ide-plugin/tests/fixtures/symbols/dist/plugin.wasm.sources

@@ -1 +1 @@
-4524cab0ceac631153a945f6b76f7d40efd3c854740ae22c64580381e9532397
+3da1a09906d803234016b3f9c30a88b9b40bf3187fc73840ff60a2e05f504b48

crates/ide-plugin/tests/fixtures/tables/dist/plugin.wasm.sources

@@ -1 +1 @@
-a92f4def072ca4cc805414516ab4f046fc54bcf11394a5413a27ea151c156174
+39e7a805120ce6433750c32b1d670b3caba990f7b15aea866a29c23b01cba708

crates/ide-plugin/tests/fixtures/web-content/dist/plugin.wasm.sources

@@ -1 +1 @@
-994fca61bc5a10f0229301406af76c188a9cb2f593db85a403c1ece746e9f7b5
+5ec9be607955ce2aa4d921884df17c49af3ce98945f8fa641cec9a7f1b4d8384

crates/ide-plugin/tests/fixtures/web-log/dist/plugin.wasm.sources

@@ -1 +1 @@
-48eaf97f57cc08c3854a1effa37ebf29defca4782f76c7de1da6ef9a02c23441
+f05df5c2faf1718ba9702be4d979c367ea8445a854794bb21e8e36b211f18122

crates/ide-plugin/tests/fixtures/web-pty/dist/plugin.wasm.sources

@@ -1 +1 @@
-b896043cf261ff4bb19977f4648a736907fa897b8d4f0804077678a5895d1845
+548cb8321b63b0685049fcf796dbc8390fcb22f3c1ffcfa09452e5a63382d27d

crates/ide-profiler/src/formats.rs

@@ -109,6 +109,17 @@ pub(crate) fn cpuprofile_runs_code_of(json: &str, root: &Path) -> bool {
     })
 }
 
+/// The file on disk of one `$vscode.locations` entry and its 0-based line. The entry lists a
+/// frame's places in order: the source it was mapped to, then the script that ran, which a
+/// page serves from a URL and has no file.
+fn source_location(entry: &Value) -> Option<(PathBuf, u32)> {
+    entry.get("locations")?.as_array()?.iter().find_map(|l| {
+        let path = Path::new(l.pointer("/source/path")?.as_str()?);
+        let line = l.get("lineNumber")?.as_u64()?;
+        path.is_absolute().then(|| (path.to_path_buf(), line.saturating_sub(1) as u32))
+    })
+}
+
 /// Adds a V8 CPU profile (`node --cpu-prof`), weighted by sampled time in milliseconds.
 pub(crate) fn add_cpuprofile(b: &mut TreeBuilder, json: &str) -> Result<(), String> {
     let v: Value = serde_json::from_str(json).map_err(|e| e.to_string())?;
@@ -146,6 +157,8 @@ pub(crate) fn add_cpuprofile(b: &mut TreeBuilder, json: &str) -> Result<(), Stri
             }
         }
     }
+    // A recording made through a debugger (js-debug) says where each frame is in the sources.
+    let mapped = v.pointer("/$vscode/locations").and_then(Value::as_array);
     let frame_of = |n: &Value| -> Option<FrameKey> {
         let cf = n.get("callFrame")?;
         let name = cf.get("functionName").and_then(Value::as_str).unwrap_or_default();
@@ -153,10 +166,22 @@ pub(crate) fn add_cpuprofile(b: &mut TreeBuilder, json: &str) -> Result<(), Stri
         if name == "(root)" {
             return None;
         }
-        let file = url_path(url);
         let name = if name.is_empty() { "(anonymous)".to_owned() } else { name.to_owned() };
-        let line =
-            file.as_ref().and(cf.get("lineNumber").and_then(Value::as_i64)).filter(|l| *l >= 0).map(|l| l as u32);
+        let (file, line) = n
+            .get("locationId")
+            .and_then(Value::as_u64)
+            .and_then(|id| mapped?.get(id as usize))
+            .and_then(source_location)
+            .map(|(file, line)| (Some(file), Some(line)))
+            .unwrap_or_else(|| {
+                let file = url_path(url);
+                let line = file
+                    .as_ref()
+                    .and(cf.get("lineNumber").and_then(Value::as_i64))
+                    .filter(|l| *l >= 0)
+                    .map(|l| l as u32);
+                (file, line)
+            });
         Some(FrameKey { name, file, line, kind: ProfileFrameKind::Code })
     };
     for (id, weight) in self_time {
@@ -301,6 +326,32 @@ mod tests {
         assert!(add_cpuprofile(&mut TreeBuilder::new(), "{}").is_err());
     }
 
+    #[test]
+    fn cpuprofile_frames_take_the_source_a_debugger_mapped_them_to() {
+        // js-debug's recording of a page: scripts are URLs, and `$vscode.locations` holds where
+        // each frame is in the sources (1-based lines), first the mapped file, then the script.
+        let json = r#"{"nodes":[
+            {"id":1,"callFrame":{"functionName":"(root)","url":"","lineNumber":-1},"children":[2,3,4]},
+            {"id":2,"callFrame":{"functionName":"increment","url":"http://localhost:5173/src/App.vue","lineNumber":40},"hitCount":3,"locationId":0},
+            {"id":3,"callFrame":{"functionName":"inline","url":"http://localhost:5173/","lineNumber":9},"hitCount":1,"locationId":1},
+            {"id":4,"callFrame":{"functionName":"(idle)","url":"","lineNumber":-1},"hitCount":1,"locationId":2}],
+            "$vscode":{"rootPath":"/work/shop","locations":[
+              {"locations":[
+                {"lineNumber":13,"columnNumber":10,"source":{"path":"/work/shop/src/App.vue","sourceReference":0}},
+                {"lineNumber":41,"columnNumber":21,"source":{"path":"localhost꞉5173/src/App.vue","sourceReference":7}}]},
+              {"locations":[{"lineNumber":10,"columnNumber":1,"source":{"path":"localhost꞉5173/","sourceReference":9}}]},
+              {"locations":[]}]}}"#;
+        let mut b = TreeBuilder::new();
+        add_cpuprofile(&mut b, json).unwrap();
+        let p = b.finish("node", "samples", ProfileMode::Cpu);
+        let frame = |name: &str| p.frames.iter().find(|f| f.name == name).unwrap();
+        assert_eq!(frame("increment").file.as_deref(), Some(Path::new("/work/shop/src/App.vue")));
+        assert_eq!(frame("increment").line, Some(12));
+        // No file on disk behind the frame: it stays without one.
+        assert_eq!((frame("inline").file.as_deref(), frame("inline").line), (None, None));
+        assert_eq!(frame("(idle)").file, None);
+    }
+
     #[test]
     fn cpuprofile_without_deltas_uses_hit_counts() {
         let json = r#"{"nodes":[{"id":1,"callFrame":{"functionName":"(root)","url":""},"children":[2]},

crates/ide-remote/src/docker.rs

@@ -178,6 +178,47 @@ pub fn container_config(config: &RunConfig, run: &ContainerRun) -> IdeResult<Run
     Ok(out)
 }
 
+/// The docker CLI arguments that run `python -c code` in a new container of the target's
+/// image or service, named `name`. The container is kept when it exits, so `docker cp` can
+/// copy from it while nothing runs; the caller removes it. The image's entrypoint is
+/// skipped (it may wait for other services), as are the service's dependencies.
+pub fn python_probe_args(target: &RunTarget, root: &Path, name: &str, code: &str) -> IdeResult<Vec<String>> {
+    let python = match target.python.trim() {
+        "" => "python3",
+        python => python,
+    };
+    let mut args: Vec<String> = Vec::new();
+    match target.kind {
+        RunTargetKind::Docker => {
+            if target.image.trim().is_empty() {
+                return Err(IdeError::invalid(format!("Run target '{}' has no image", target.name)));
+            }
+            args.push("run".into());
+        }
+        RunTargetKind::Compose => {
+            if target.service.trim().is_empty() {
+                return Err(IdeError::invalid(format!("Run target '{}' has no service", target.name)));
+            }
+            args.push("compose".into());
+            for file in target.compose_files.iter().map(|f| f.trim()).filter(|f| !f.is_empty()) {
+                args.extend(["--file".into(), root.join(file).to_string_lossy().into_owned()]);
+            }
+            args.extend(["run", "--no-deps", "--no-TTY"].map(String::from));
+        }
+        RunTargetKind::Ssh => {
+            return Err(IdeError::invalid(format!("Run target '{}' is not a container", target.name)));
+        }
+    }
+    args.extend(["--name".into(), name.to_owned(), "--label".into(), "openidea.python-probe=true".into()]);
+    args.extend(["--entrypoint".into(), python.to_owned()]);
+    args.push(match target.kind {
+        RunTargetKind::Compose => target.service.trim().to_owned(),
+        _ => target.image.trim().to_owned(),
+    });
+    args.extend(["-c".into(), code.to_owned()]);
+    Ok(args)
+}
+
 /// Project managers whose `run` executes in the project's environment (`uv run python …`).
 const PYTHON_RUNNERS: [&str; 6] = ["uv", "poetry", "pdm", "pipenv", "hatch", "rye"];
 
@@ -429,6 +470,34 @@ mod tests {
         assert!(container_config(&c, &run(&target, &none, &none)).unwrap_err().message.contains("no service"));
     }
 
+    #[cfg(unix)]
+    #[test]
+    fn python_probe_runs_the_interpreter_in_a_kept_container() {
+        let root = Path::new("/work/proj");
+        let target = RunTarget {
+            kind: RunTargetKind::Compose,
+            compose_files: vec!["compose.yaml".into()],
+            service: "web".into(),
+            python: "/venv/bin/python".into(),
+            run_options: "--rm".into(),
+            ..Default::default()
+        };
+        assert_eq!(
+            python_probe_args(&target, root, "openidea-python-1", "print(1)").unwrap().join(" "),
+            "compose --file /work/proj/compose.yaml run --no-deps --no-TTY --name openidea-python-1 \
+             --label openidea.python-probe=true --entrypoint /venv/bin/python web -c print(1)"
+        );
+        let target = RunTarget { kind: RunTargetKind::Docker, image: "python:3.12".into(), ..Default::default() };
+        assert_eq!(
+            python_probe_args(&target, root, "p", "x").unwrap().join(" "),
+            "run --name p --label openidea.python-probe=true --entrypoint python3 python:3.12 -c x"
+        );
+        let ssh = RunTarget { name: "box".into(), ..Default::default() };
+        assert!(python_probe_args(&ssh, root, "p", "x").unwrap_err().message.contains("not a container"));
+        let empty = RunTarget { kind: RunTargetKind::Compose, name: "c".into(), ..Default::default() };
+        assert!(python_probe_args(&empty, root, "p", "x").unwrap_err().message.contains("no service"));
+    }
+
     /// The container's command line of `c` debugged on `target` (after the image).
     #[cfg(unix)]
     fn debugged(target: &RunTarget, c: &RunConfig) -> IdeResult<Vec<String>> {

crates/ide-run/tests/dotnet.rs

@@ -68,6 +68,8 @@ fn profiles_filter_and_preserve_launch_properties() {
     assert_eq!(p["http"].command_line_args, "--message \"hello world\"");
     assert_eq!(p["http"].working_directory, "work");
     assert!(parse_profiles("invalid").is_empty());
+    // Visual Studio saves launchSettings.json with a byte order mark.
+    assert_eq!(parse_profiles(&format!("\u{feff}{PROFILES}")).len(), 2);
 }
 
 #[test]

crates/ide-sdk/src/apply.rs

@@ -69,7 +69,11 @@ pub fn ruff_configuration(root: &Path, configured: &str) -> IdeResult<Option<Pat
 /// root, else the Python the project pins for mise / asdf. A configured
 /// interpreter whose executable is gone (uninstalled, moved) is skipped like
 /// PyCharm's "Invalid" SDKs, so runs fall back instead of failing on a dead path.
+/// `None` when the project interpreter is a run target's (see [`crate::container_python`]).
 pub fn python_interpreter(root: &Path, s: &Settings) -> Option<PathBuf> {
+    if s.languages.python.run_target().is_some() {
+        return None;
+    }
     setting_path(root, &s.languages.python.interpreter)
         .filter(|p| p.is_file())
         .or_else(|| project_venv_python(root))
@@ -78,6 +82,9 @@ pub fn python_interpreter(root: &Path, s: &Settings) -> Option<PathBuf> {
 
 /// An explicit project interpreter wins; otherwise use the closest virtualenv to the file.
 pub fn python_interpreter_near(root: &Path, near: Option<&Path>, s: &Settings) -> Option<PathBuf> {
+    if s.languages.python.run_target().is_some() {
+        return None;
+    }
     if let Some(python) = setting_path(root, &s.languages.python.interpreter).filter(|p| p.is_file()) {
         return Some(python);
     }
@@ -1156,6 +1163,7 @@ pub fn configure_server(cfg: &mut LanguageServerConfig, root: &Path, server_root
     {
         cfg.command = native.to_string_lossy().into_owned();
         cfg.args = vec!["--lsp".into(), "--stdio".into()];
+        cfg.display_name = Some("TypeScript 7".into());
         cfg.initialization_options = None;
         cfg.tsserver_project = false;
         return;
@@ -1299,6 +1307,7 @@ fn custom_server(name: &str, ls: &LanguageServerSettings) -> LanguageServerConfi
         tsserver_project: false,
         tsserver_project_extras: Default::default(),
         resync_on_configuration: false,
+        display_name: None,
         pinned: None,
     }
 }
@@ -1476,6 +1485,9 @@ pub fn run_target<'a>(config: &RunConfig, settings: &'a Settings) -> Option<&'a
         || matches!(config.kind.as_str(), "node" | "npm" | "vitest" | "jest" | "mocha")
     {
         &settings.languages.node.run_target
+    } else if let Some(target) = settings.languages.python.run_target().filter(|_| is_python_config(config, &name)) {
+        // The project interpreter is a run target's: Python runs there.
+        return Some(target);
     } else {
         return non_empty(&settings.run.default_target);
     };
@@ -1488,6 +1500,10 @@ pub fn run_target<'a>(config: &RunConfig, settings: &'a Settings) -> Option<&'a
     }
 }
 
+fn is_python_config(config: &RunConfig, program: &str) -> bool {
+    matches!(config.kind.as_str(), "python" | "pytest" | "django-test") || is_python_command(program)
+}
+
 /// Whether the configuration's `JAVA_HOME` is the one Settings choose (the Maven runner JRE,
 /// the Gradle JVM) rather than a choice of its own: an IDE-generated build-tool configuration —
 /// a Maven goal or Gradle task from the tool window — carries the model's `JAVA_HOME`, which

crates/ide-sdk/src/container_python.rs

@@ -0,0 +1,418 @@
+//! A Docker or Compose run target's Python as the project interpreter
+//! (`languages.python.interpreter = "target:<id>"`, PyCharm's Docker / Docker Compose
+//! interpreter).
+//!
+//! basedpyright / pyright run on this machine, so the library folders of the
+//! container's `sys.path` are copied here once per image (a snapshot) and given to
+//! the server as `extraPaths`. Its interpreter is a neutral one: an empty virtualenv
+//! the IDE creates, so no local site-packages mix in. Without any local Python the
+//! server gets `extraPaths` alone and its bundled typeshed standard library.
+//!
+//! The snapshot is read-only: packages change in the image (requirements, Dockerfile)
+//! and a rebuilt image gets a new snapshot. Taking one runs the docker CLI (`ide-host`).
+
+use crate::apply::merge_init_options;
+use crate::exec::{query_in, which};
+use crate::libraries::{LibraryGroup, LibraryRoot};
+use crate::python::PythonPackage;
+use ide_core::{IdeError, IdeResult};
+use ide_language::LanguageServerConfig;
+use serde::{Deserialize, Serialize};
+use serde_json::json;
+use std::path::{Path, PathBuf};
+use std::time::Duration;
+
+/// Run in the container with `python -c`: prints [`PROBE_MARKER`] and a JSON
+/// [`Probe`] (an entrypoint may print more around it).
+pub const PROBE: &str = "import json,os,sys,sysconfig\n\
+p=sysconfig.get_paths()\n\
+print('OPENIDEA-PYTHON '+json.dumps({'version':'%d.%d.%d'%sys.version_info[:3],\
+'executable':sys.executable,'stdlib':[p.get('stdlib'),p.get('platstdlib')],\
+'path':[x for x in sys.path if x and os.path.isdir(x)]}))";
+const PROBE_MARKER: &str = "OPENIDEA-PYTHON ";
+
+/// What [`PROBE`] prints about the container's interpreter.
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
+pub struct Probe {
+    /// `3.12.7`.
+    pub version: String,
+    pub executable: String,
+    /// `stdlib` and `platstdlib` of `sysconfig`.
+    pub stdlib: Vec<Option<String>>,
+    /// The folders of `sys.path`, in order.
+    pub path: Vec<String>,
+}
+
+pub fn parse_probe(out: &str) -> IdeResult<Probe> {
+    let json = out
+        .lines()
+        .rev()
+        .find_map(|l| l.trim().strip_prefix(PROBE_MARKER))
+        .ok_or_else(|| IdeError::internal(format!("the container's Python printed no paths: {}", out.trim())))?;
+    serde_json::from_str(json).map_err(|e| IdeError::internal(format!("cannot read the container's Python paths: {e}")))
+}
+
+/// The container folders a snapshot copies: the `sys.path` folders outside the standard
+/// library (its stubs come with the server) and outside the project, which is here already.
+/// A folder inside another one of the list is copied with it.
+pub fn folders_to_copy(probe: &Probe, container_root: &str) -> Vec<String> {
+    let under = |path: &str, dir: &str| {
+        let dir = dir.trim_end_matches('/');
+        path == dir || path.starts_with(&format!("{dir}/")) || dir.is_empty()
+    };
+    let stdlib: Vec<&str> = probe.stdlib.iter().flatten().map(String::as_str).collect();
+    // `site-packages` lives inside the standard library's folder.
+    let packages = |path: &str| path.split('/').any(|c| c == "site-packages" || c == "dist-packages");
+    let mut out: Vec<String> = Vec::new();
+    for path in &probe.path {
+        let path = path.trim_end_matches('/');
+        if !path.starts_with('/')
+            || (stdlib.iter().any(|s| under(path, s)) && !packages(path))
+            || (!container_root.trim().is_empty() && under(path, container_root))
+            || out.iter().any(|o| under(path, o))
+        {
+            continue;
+        }
+        out.retain(|o| !under(o, path));
+        out.push(path.to_owned());
+    }
+    out
+}
+
+/// Where a snapshot in `dir` keeps its copy of the container folder `container`.
+pub fn local_folder(dir: &Path, container: &str) -> PathBuf {
+    container.split('/').filter(|c| !c.is_empty() && *c != "." && *c != "..").fold(dir.join("fs"), |p, c| p.join(c))
+}
+
+/// `snapshot.json` of a snapshot folder.
+#[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize)]
+#[serde(default, rename_all = "camelCase")]
+pub struct Snapshot {
+    /// `sha256:…` of the image the folders were copied from.
+    pub image: String,
+    pub probe: Probe,
+    /// The copied container folders ([`local_folder`] has them here).
+    pub folders: Vec<String>,
+    /// The neutral interpreter given to the language server; `None` without a local Python.
+    pub neutral_python: Option<PathBuf>,
+}
+
+const SNAPSHOT_FILE: &str = "snapshot.json";
+/// Names the snapshot folder in use, in the target's folder.
+const CURRENT_FILE: &str = "current";
+
+/// A target's snapshots: `<cache>/<target>/<image>/`.
+pub fn target_dir(cache: &Path, target_id: &str) -> PathBuf {
+    cache.join(dir_name(target_id))
+}
+
+/// The folder name of an image id or target id.
+pub fn dir_name(id: &str) -> String {
+    let id = id.strip_prefix("sha256:").map(|hex| &hex[..hex.len().min(16)]).unwrap_or(id);
+    let name: String =
+        id.chars().map(|c| if c.is_ascii_alphanumeric() || c == '-' || c == '_' { c } else { '_' }).collect();
+    if name.is_empty() { "_".into() } else { name }
+}
+
+/// The snapshot in use for the target whose folder is `target_dir`, with its folder.
+pub fn current(target_dir: &Path) -> Option<(PathBuf, Snapshot)> {
+    let name = std::fs::read_to_string(target_dir.join(CURRENT_FILE)).ok()?;
+    let dir = target_dir.join(dir_name(name.trim()));
+    read(&dir).map(|s| (dir, s))
+}
+
+/// The complete snapshot in `dir`, if there is one.
+pub fn read(dir: &Path) -> Option<Snapshot> {
+    serde_json::from_str(&std::fs::read_to_string(dir.join(SNAPSHOT_FILE)).ok()?).ok()
+}
+
+/// Writes `snapshot.json` (last: a folder without it is incomplete).
+pub fn write(dir: &Path, snapshot: &Snapshot) -> IdeResult<()> {
+    let json = serde_json::to_string_pretty(snapshot).map_err(|e| IdeError::internal(e.to_string()))?;
+    std::fs::write(dir.join(SNAPSHOT_FILE), json)?;
+    Ok(())
+}
+
+/// Makes the snapshot of `image` the one in use and removes the target's other snapshots.
+pub fn make_current(target_dir: &Path, image: &str) -> IdeResult<()> {
+    let keep = dir_name(image);
+    std::fs::write(target_dir.join(CURRENT_FILE), &keep)?;
+    for entry in std::fs::read_dir(target_dir)?.flatten() {
+        let path = entry.path();
+        if path.is_dir()
+            && entry.file_name().to_string_lossy() != keep.as_str()
+            && let Err(e) = std::fs::remove_dir_all(&path)
+        {
+            tracing::warn!("cannot remove the old Python snapshot {}: {e}", path.display());
+        }
+    }
+    Ok(())
+}
+
+/// The local folders of a snapshot that exist.
+pub fn local_folders(dir: &Path, snapshot: &Snapshot) -> Vec<PathBuf> {
+    snapshot.folders.iter().map(|f| local_folder(dir, f)).filter(|p| p.is_dir()).collect()
+}
+
+/// basedpyright / pyright: the neutral interpreter and the snapshot's folders as
+/// `extraPaths`. Without a snapshot yet the server only loses the local interpreter.
+pub fn configure_server(cfg: &mut LanguageServerConfig, snapshot: Option<(&Path, &Snapshot)>) {
+    let section = match cfg.name.as_str() {
+        "basedpyright" => "basedpyright",
+        "pyright" => "python",
+        _ => return,
+    };
+    let Some((dir, snapshot)) = snapshot else { return };
+    if let Some(python) = snapshot.neutral_python.as_deref().filter(|p| p.is_file()) {
+        merge_init_options(cfg, json!({ "python": { "pythonPath": python.to_string_lossy() } }));
+        if let Some(venv) = crate::venv_of(python) {
+            cfg.env.insert("VIRTUAL_ENV".into(), venv.to_string_lossy().into_owned());
+        }
+    }
+    let paths: Vec<String> = local_folders(dir, snapshot).iter().map(|p| p.to_string_lossy().into_owned()).collect();
+    merge_init_options(cfg, json!({ "settings": { section: { "analysis": { "extraPaths": paths } } } }));
+}
+
+/// External Libraries: the snapshot's folders, named after the target.
+pub fn library_group(target_name: &str, dir: &Path, snapshot: &Snapshot) -> Option<LibraryGroup> {
+    let short = snapshot.probe.version.split('.').take(2).collect::<Vec<_>>().join(".");
+    let roots: Vec<LibraryRoot> = snapshot
+        .folders
+        .iter()
+        .map(|f| (f, local_folder(dir, f)))
+        .filter(|(_, p)| p.is_dir())
+        .map(|(f, p)| LibraryRoot { name: f.rsplit('/').next().unwrap_or(f).to_owned(), path: p.into() })
+        .collect();
+    (!roots.is_empty()).then(|| LibraryGroup {
+        name: format!("Python {short} ({target_name})"),
+        kind: "python".into(),
+        roots,
+    })
+}
+
+/// The packages of a snapshot, from the `*.dist-info` / `*.egg-info` metadata it copied.
+pub fn packages(dir: &Path, snapshot: &Snapshot) -> Vec<PythonPackage> {
+    let mut out: Vec<PythonPackage> = Vec::new();
+    for folder in local_folders(dir, snapshot) {
+        let Ok(entries) = std::fs::read_dir(&folder) else { continue };
+        for entry in entries.flatten() {
+            let name = entry.file_name().to_string_lossy().into_owned();
+            let path = entry.path();
+            let metadata = if name.ends_with(".dist-info") {
+                path.join("METADATA")
+            } else if name.ends_with(".egg-info") {
+                if path.is_dir() { path.join("PKG-INFO") } else { path }
+            } else {
+                continue;
+            };
+            let Some(package) = std::fs::read_to_string(&metadata).ok().and_then(|m| package_of(&m)) else {
+                continue;
+            };
+            if !out.iter().any(|p| p.name.eq_ignore_ascii_case(&package.name)) {
+                out.push(package);
+            }
+        }
+    }
+    out.sort_by_key(|p| p.name.to_lowercase());
+    out
+}
+
+fn package_of(metadata: &str) -> Option<PythonPackage> {
+    let header = |key: &str| {
+        metadata
+            .lines()
+            .take_while(|l| !l.is_empty())
+            .find_map(|l| l.strip_prefix(key).and_then(|v| v.strip_prefix(':')))
+            .map(|v| v.trim().to_owned())
+    };
+    Some(PythonPackage { name: header("Name")?, version: header("Version").unwrap_or_default() })
+}
+
+/// The neutral interpreter for a container Python of `version`: an empty virtualenv in
+/// `cache`, made from a local Python of the same minor version when there is one. `None`
+/// when this machine has no Python at all.
+pub fn neutral_python(cache: &Path, version: &str) -> Option<PathBuf> {
+    neutral_python_with(cache, version, which)
+}
+
+pub(crate) fn neutral_python_with(
+    cache: &Path,
+    version: &str,
+    which: impl Fn(&str) -> Option<PathBuf>,
+) -> Option<PathBuf> {
+    let short = version.split('.').take(2).collect::<Vec<_>>().join(".");
+    let named = (!short.is_empty()).then(|| format!("python{short}"));
+    let (base, label) = match named.as_deref().and_then(|n| which(n).map(|p| (p, short.clone()))) {
+        Some(found) => found,
+        None => (which("python3").or_else(|| which("python"))?, "default".to_owned()),
+    };
+    let venv = cache.join("neutral").join(label);
+    let python = venv.join(crate::bin_dir()).join(crate::exe("python"));
+    if python.is_file() && venv.join("pyvenv.cfg").is_file() {
+        return Some(python);
+    }
+    std::fs::create_dir_all(&venv).ok()?;
+    let location = venv.to_string_lossy().into_owned();
+    query_in(&base, &["-m", "venv", "--without-pip", &location], None, &[], Duration::from_secs(60));
+    python.is_file().then_some(python)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::tests::server;
+
+    fn probe() -> Probe {
+        Probe {
+            version: "3.12.7".into(),
+            executable: "/usr/local/bin/python3".into(),
+            stdlib: vec![Some("/usr/local/lib/python3.12".into()), Some("/usr/local/lib/python3.12".into())],
+            path: [
+                "/workspaces/app",
+                "/workspaces/app/src",
+                "/usr/local/lib/python3.12",
+                "/usr/local/lib/python3.12/lib-dynload",
+                "/opt/lib/extra",
+                "/usr/local/lib/python3.12/site-packages",
+                "/usr/local/lib/python3.12/site-packages/setuptools/_vendor",
+                "relative",
+            ]
+            .map(String::from)
+            .to_vec(),
+        }
+    }
+
+    #[test]
+    fn copies_library_folders_outside_the_stdlib_and_the_project() {
+        assert_eq!(
+            folders_to_copy(&probe(), "/workspaces/app"),
+            ["/opt/lib/extra", "/usr/local/lib/python3.12/site-packages"]
+        );
+        let mut p = probe();
+        p.path.insert(0, "/opt/lib/extra/inner".into());
+        assert_eq!(folders_to_copy(&p, "/workspaces/app")[0], "/opt/lib/extra", "the outer folder replaces the inner");
+    }
+
+    #[test]
+    fn reads_the_probe_after_other_output() {
+        let line = format!("{PROBE_MARKER}{}", serde_json::to_string(&probe()).unwrap());
+        let out = format!("waiting for the entrypoint\n{line}\nbye\n");
+        assert_eq!(parse_probe(&out).unwrap(), probe());
+        assert!(parse_probe("python3: not found").unwrap_err().message.contains("not found"));
+    }
+
+    #[test]
+    fn mirrors_container_paths_and_names_folders() {
+        let dir = Path::new("snap");
+        assert_eq!(
+            local_folder(dir, "/usr/local/lib/../site-packages"),
+            Path::new("snap").join("fs").join("usr").join("local").join("lib").join("site-packages")
+        );
+        assert_eq!(dir_name("sha256:0123456789abcdef0123"), "0123456789abcdef");
+        assert_eq!(dir_name("target/../x y"), "target____x_y");
+    }
+
+    fn snapshot_in(dir: &Path, neutral: Option<PathBuf>) -> Snapshot {
+        let snapshot = Snapshot {
+            image: "sha256:abc".into(),
+            probe: probe(),
+            folders: vec!["/usr/local/lib/python3.12/site-packages".into(), "/gone".into()],
+            neutral_python: neutral,
+        };
+        let site = local_folder(dir, &snapshot.folders[0]);
+        std::fs::create_dir_all(site.join("Django-5.1.3.dist-info")).unwrap();
+        std::fs::write(
+            site.join("Django-5.1.3.dist-info/METADATA"),
+            "Metadata-Version: 2.1\nName: Django\nVersion: 5.1.3\n\nName: not a header\n",
+        )
+        .unwrap();
+        std::fs::create_dir_all(site.join("asgiref-3.8.1.dist-info")).unwrap();
+        std::fs::write(site.join("asgiref-3.8.1.dist-info/METADATA"), "Name: asgiref\nVersion: 3.8.1\n").unwrap();
+        std::fs::write(site.join("legacy.egg-info"), "Name: legacy\nVersion: 0.1\n").unwrap();
+        snapshot
+    }
+
+    #[test]
+    fn lists_packages_and_library_roots_of_a_snapshot() {
+        let tmp = tempfile::tempdir().unwrap();
+        let snapshot = snapshot_in(tmp.path(), None);
+        let names: Vec<String> =
+            packages(tmp.path(), &snapshot).into_iter().map(|p| format!("{} {}", p.name, p.version)).collect();
+        assert_eq!(names, ["asgiref 3.8.1", "Django 5.1.3", "legacy 0.1"]);
+        let group = library_group("web", tmp.path(), &snapshot).unwrap();
+        assert_eq!(group.name, "Python 3.12 (web)");
+        assert_eq!(group.roots.len(), 1, "a folder that was not copied is left out");
+        assert_eq!(group.roots[0].name, "site-packages");
+    }
+
+    #[test]
+    fn current_snapshot_switches_and_drops_old_ones() {
+        let tmp = tempfile::tempdir().unwrap();
+        let target = target_dir(tmp.path(), "web");
+        for image in ["sha256:old", "sha256:new"] {
+            let dir = target.join(dir_name(image));
+            std::fs::create_dir_all(&dir).unwrap();
+            write(&dir, &Snapshot { image: image.into(), ..Default::default() }).unwrap();
+        }
+        std::fs::create_dir_all(target.join("new.partial")).unwrap();
+        assert!(current(&target).is_none());
+        make_current(&target, "sha256:new").unwrap();
+        let (dir, snapshot) = current(&target).unwrap();
+        assert_eq!((dir, snapshot.image.as_str()), (target.join("new"), "sha256:new"));
+        assert!(!target.join("old").exists() && !target.join("new.partial").exists());
+    }
+
+    #[test]
+    fn basedpyright_gets_the_neutral_interpreter_and_extra_paths() {
+        let tmp = tempfile::tempdir().unwrap();
+        let venv = tmp.path().join("neutral");
+        let python = venv.join(crate::bin_dir()).join(crate::exe("python"));
+        std::fs::create_dir_all(python.parent().unwrap()).unwrap();
+        std::fs::write(&python, "").unwrap();
+        std::fs::write(venv.join("pyvenv.cfg"), "include-system-site-packages = false\n").unwrap();
+        let snapshot = snapshot_in(tmp.path(), Some(python.clone()));
+        let site = local_folder(tmp.path(), &snapshot.folders[0]).to_string_lossy().into_owned();
+
+        let mut cfg = server("basedpyright");
+        configure_server(&mut cfg, Some((tmp.path(), &snapshot)));
+        let opts = serde_json::to_value(cfg.initialization_options.as_ref().unwrap()).unwrap();
+        assert_eq!(opts["python"]["pythonPath"], python.to_string_lossy().as_ref());
+        assert_eq!(opts["settings"]["basedpyright"]["analysis"]["extraPaths"], json!([site]));
+        assert_eq!(cfg.env["VIRTUAL_ENV"], venv.to_string_lossy().as_ref());
+
+        let mut cfg = server("pyright");
+        configure_server(&mut cfg, Some((tmp.path(), &snapshot)));
+        let opts = serde_json::to_value(cfg.initialization_options.as_ref().unwrap()).unwrap();
+        assert_eq!(opts["settings"]["python"]["analysis"]["extraPaths"], json!([site]));
+
+        let mut cfg = server("ruff");
+        configure_server(&mut cfg, Some((tmp.path(), &snapshot)));
+        assert!(cfg.initialization_options.is_none());
+    }
+
+    #[test]
+    fn without_a_local_python_only_extra_paths_reach_the_server() {
+        let tmp = tempfile::tempdir().unwrap();
+        assert_eq!(neutral_python_with(tmp.path(), "3.12.7", |_| None), None);
+        let snapshot = snapshot_in(tmp.path(), None);
+        let mut cfg = server("basedpyright");
+        configure_server(&mut cfg, Some((tmp.path(), &snapshot)));
+        let opts = serde_json::to_value(cfg.initialization_options.as_ref().unwrap()).unwrap();
+        assert!(opts.get("python").is_none(), "no pythonPath: the server falls back to its bundled typeshed");
+        assert_eq!(opts["settings"]["basedpyright"]["analysis"]["extraPaths"].as_array().unwrap().len(), 1);
+        assert!(!cfg.env.contains_key("VIRTUAL_ENV"));
+    }
+
+    // A real `python3 -m venv`: runs where a Python is installed (the dev container, CI).
+    #[test]
+    fn neutral_python_is_an_empty_virtualenv() {
+        let Some(base) = which("python3") else { return };
+        let tmp = tempfile::tempdir().unwrap();
+        let which = |name: &str| (name == "python3").then(|| base.clone());
+        let python = neutral_python_with(tmp.path(), "0.0.1", which).unwrap();
+        assert!(python.starts_with(tmp.path().join("neutral").join("default")));
+        let cfg = std::fs::read_to_string(crate::venv_of(&python).unwrap().join("pyvenv.cfg")).unwrap();
+        assert!(cfg.contains("include-system-site-packages = false"));
+        assert_eq!(neutral_python_with(tmp.path(), "0.0.1", which), Some(python), "reused");
+    }
+}

crates/ide-sdk/src/lib.rs

@@ -9,6 +9,7 @@ mod angular;
 pub mod apply;
 pub mod arduino;
 mod astro;
+pub mod container_python;
 mod discover;
 mod exec;
 pub mod go;

crates/ide-sdk/src/libraries.rs

@@ -254,6 +254,10 @@ fn module_settings(root: &Path, settings: &Settings) -> Settings {
         &mut l.go.gopath,
         &mut l.java.jdk,
     ] {
+        // `target:<id>` names a run target, not a path.
+        if value.trim().starts_with(ide_core::settings::PythonSettings::TARGET_PREFIX) {
+            continue;
+        }
         if let Some(path) = crate::apply::setting_path(root, value) {
             *value = path.to_string_lossy().into_owned();
         }

crates/ide-sdk/src/tests.rs

@@ -21,7 +21,7 @@ fn fake_venv(root: &Path, name: &str) -> std::path::PathBuf {
     py
 }
 
-fn server(name: &str) -> LanguageServerConfig {
+pub(crate) fn server(name: &str) -> LanguageServerConfig {
     LanguageServerConfig {
         name: name.into(),
         command: name.into(),
@@ -42,6 +42,7 @@ fn server(name: &str) -> LanguageServerConfig {
         tsserver_project: false,
         tsserver_project_extras: Default::default(),
         resync_on_configuration: false,
+        display_name: None,
         pinned: None,
     }
 }
@@ -188,6 +189,48 @@ fn pyright_gets_python_path_and_venv_env() {
     assert!(cfg.env["PATH"].starts_with(&*tmp.path().join(".venv").join(bin_dir()).to_string_lossy()));
 }
 
+#[test]
+fn a_run_target_interpreter_hides_local_pythons() {
+    let tmp = tempfile::tempdir().unwrap();
+    fake_venv(tmp.path(), ".venv");
+    let mut s = Settings::default();
+    s.languages.python.interpreter = "target:web".into();
+    assert_eq!(python_interpreter(tmp.path(), &s), None, "the project virtualenv is not the interpreter");
+    assert_eq!(terminal_activation(tmp.path(), &s, "bash"), None);
+    assert!(!tool_install_environment(tmp.path(), &s).commands.contains_key("python"));
+    let mut cfg = server("basedpyright");
+    configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
+    let opts = cfg.initialization_options.map(|o| serde_json::to_value(o).unwrap());
+    assert!(opts.and_then(|o| o.pointer("/python/pythonPath").cloned()).is_none());
+    assert!(!cfg.env.contains_key("VIRTUAL_ENV"));
+}
+
+#[test]
+fn python_configurations_run_on_the_interpreters_target() {
+    let tmp = tempfile::tempdir().unwrap();
+    fake_venv(tmp.path(), ".venv");
+    let mut s = Settings::default();
+    s.languages.python.interpreter = "target:web".into();
+    s.run.default_target = "box".into();
+    let mut own = run("python", "python3", &["main.py"]);
+    own.extras.target = Some(String::new());
+    let mut configs = vec![
+        run("python", "python3", &["manage.py", "runserver"]),
+        run("pytest", "python3", &["-m", "pytest"]),
+        run("npm", "npm", &["run", "dev"]),
+        own,
+    ];
+    apply_to_run_configs(&mut configs, tmp.path(), &s);
+    assert_eq!(configs[0].extras.target.as_deref(), Some("web"));
+    assert_eq!(configs[0].command, "python3", "the container resolves the interpreter");
+    assert!(!configs[0].env.contains_key("VIRTUAL_ENV"));
+    assert_eq!(configs[1].extras.target.as_deref(), Some("web"));
+    assert_eq!(configs[2].extras.target.as_deref(), Some("box"), "other languages keep the default target");
+    assert_eq!(configs[3].extras.target.as_deref(), Some(""), "a configuration's own choice wins");
+    let derived = without_derived(&configs[0], tmp.path(), &s);
+    assert_eq!(derived.extras.target, None, "the target is derived from the interpreter");
+}
+
 #[test]
 fn jdtls_vm_args() {
     let tmp = tempfile::tempdir().unwrap();
@@ -1387,6 +1430,7 @@ fn typescript_7_runs_its_own_language_server() {
         configure_server(&mut cfg, tmp.path(), tmp.path(), &s);
         assert_eq!(Path::new(&cfg.command), native, "{name}");
         assert_eq!(cfg.args, ["--lsp", "--stdio"]);
+        assert_eq!(cfg.display_name.as_deref(), Some("TypeScript 7"));
         assert!(cfg.initialization_options.is_none());
     }
     // Picked as a directory (its `lib`, as for older versions), too.