feat(java): Add Project JDK and Maven home / settings.xml / local repository settings

The JDK was always picked automatically (JAVA_HOME, PATH, the usual install dirs, by the
module's Java version) and Maven was the project's mvnw or mvn on PATH, with no way to
override either. languages.java.jdk (Languages & Frameworks › Java › Project JDK) now sets
the default jdtls runtime, the JDK of Run/Debug and JAVA_HOME for Maven and Gradle;
languages.java.maven (Build Tools › Maven) sets the Maven home, -s and
-Dmaven.repo.local for sync, builds, tool-window goals and detected run configurations.
JDKs and Maven installations are detected for the pickers.

Closes #13

src/bindings.ts

@@ -249,6 +249,7 @@ export const commands = {
 	 *  follow-up command. Edits the server requests arrive via `workspace/applyEdit`.
 	 */
 	lspExecuteCommand: (doc: DocId, command: Command) => typedError<null, IdeError>(__TAURI_INVOKE("lsp_execute_command", { doc, command })),
+	/**  Changes of every repository of the project. */
 	vcsStatus: () => typedError<FileStatus[], IdeError>(__TAURI_INVOKE("vcs_status")),
 	vcsBranchInfo: () => typedError<BranchInfo, IdeError>(__TAURI_INVOKE("vcs_branch_info")),
 	/**  Gutter change markers for a file, computed against its current (unsaved) text. */
@@ -2341,11 +2342,18 @@ export type JavaLaunchInfo = {
 };
 
 export type JavaSettings = {
+	/**
+	 *  Project JDK home; empty = per module, the installed JDK matching the
+	 *  Java version it targets.
+	 */
+	jdk?: string,
 	/**
 	 *  Extra JVM options for the Java language server (jdtls), space-separated
 	 *  (VS Code's `java.jdt.ls.vmargs`).
 	 */
 	jdtlsVmArgs?: string,
+	/**  Build Tools › Maven. */
+	maven?: MavenSettings,
 };
 
 /**  Editor › Code Style › <Language> › Tabs and Indents (unset fields inherit). */
@@ -2635,10 +2643,22 @@ export type MavenProject = {
 	javaVersion: number | null,
 	/**  Maven launcher: the nearest `mvnw` up to the project root (absolute), else `mvn`. */
 	command: string,
+	/**  Options before the goals (`-s`, `-Dmaven.repo.local=`); filled in by the shell from settings. */
+	options: string[],
 	/**  Environment for runs (`JAVA_HOME` of the matching JDK); filled in by the shell. */
 	env: { [key in string]: string },
 };
 
+/**  Build Tools › Maven. */
+export type MavenSettings = {
+	/**  Maven home (or its `mvn` executable); empty = the project's `mvnw`, else `mvn` on `PATH`. */
+	home?: string,
+	/**  User `settings.xml` (`-s`); empty = `~/.m2/settings.xml`. */
+	userSettings?: string,
+	/**  Local repository (`-Dmaven.repo.local`); empty = from `settings.xml`. */
+	localRepository?: string,
+};
+
 export type MemoryCategory = 
 /**  The backend and its WebView processes. */
 "app" | "languageServer" | 
@@ -3281,7 +3301,11 @@ export type Sdk = {
 /**  What [`detect`] looks for. */
 export type SdkKind = "python" | "node" | 
 /**  npm / pnpm / yarn executables. */
-"packageManager" | "rust" | "go" | "typeScript";
+"packageManager" | "rust" | "go" | "typeScript" | 
+/**  JDK homes. */
+"jdk" | 
+/**  Maven homes. */
+"maven";
 
 export type SearchEvent = { type: "file"; file: FileMatches } | { type: "done"; summary: SearchSummary };
 

src/features/build-tools/actions.test.tsx

@@ -27,6 +27,7 @@ const mavenModel: BuildModel = {
         profiles: ["ci"],
         javaVersion: 21,
         command: "/p/mvnw",
+        options: [],
         env: {},
       },
     ],

src/features/build-tools/index.ts

@@ -95,6 +95,10 @@ export function activate(): () => void {
       if ([...e.created, ...e.modified, ...e.removed].some((p) => BUILD_FILE.test(p))) scheduleLoad();
     }),
     onIdeEvent("projectRootsChanged", scheduleLoad),
+    // Project JDK / Maven home and options are applied to the model's launchers.
+    onIdeEvent("settingsChanged", (e) => {
+      if (e.key === "languages" || e.key.startsWith("languages.java")) scheduleLoad();
+    }),
     registerActions([
       {
         id: "maven.reload",

src/features/build-tools/model.test.ts

@@ -37,6 +37,7 @@ function project(over: Partial<MavenProject>): MavenProject {
     profiles: [],
     javaVersion: 21,
     command: "/p/mvnw",
+    options: [],
     env: { JAVA_HOME: "/jdk21" },
     ...over,
   };
@@ -184,6 +185,11 @@ describe("Maven runs", () => {
     const root = mavenGoalConfig(maven.projects[0]!, ["clean"], maven, { offline: false, skipTests: false, profiles: {} });
     expect(root.cwd).toBeNull();
     expect(root.isTest).toBe(false);
+    // Settings › Maven options go before the goals.
+    const configured = { ...core, options: ["-s", "/m2/settings.xml"] };
+    expect(mavenGoalConfig(configured, ["test"], maven, { offline: false, skipTests: true, profiles: {} }).args).toEqual(
+      ["-s", "/m2/settings.xml", "test", "-DskipTests"],
+    );
   });
 
   it("parses typed command lines", () => {

src/features/build-tools/model.ts

@@ -401,7 +401,7 @@ export function mavenGoalConfig(
   model: Pick<MavenModel, "profiles">,
   options: MavenRunOptions,
 ): RunConfig {
-  const args = mavenArgs(goals, model, options);
+  const args = [...project.options, ...mavenArgs(goals, model, options)];
   return {
     id: `maven:goal:${project.pom}:${goals.join(" ")}`,
     name: mavenConfigName(project, goals),

src/features/settings/__tests__/languages.test.ts

@@ -21,7 +21,7 @@ describe("languages settings", () => {
       node: { packageManager: "pip" },
       rust: { checkCommand: "clippy", checkOnSave: false },
       typescript: { version: "" },
-      java: { jdtlsVmArgs: " -Xmx2g " },
+      java: { jdtlsVmArgs: " -Xmx2g ", jdk: 21, maven: { home: " /opt/maven " } },
     });
     expect(v.python).toEqual({ interpreter: "/usr/bin/python3", activateVirtualenv: true });
     expect(v.node.packageManager).toBe("");
@@ -29,6 +29,8 @@ describe("languages settings", () => {
     expect(v.rust.checkOnSave).toBe(false);
     expect(v.typescript.version).toBe("bundled");
     expect(v.java.jdtlsVmArgs).toBe("-Xmx2g");
+    expect(v.java.jdk).toBe("");
+    expect(v.java.maven).toEqual({ home: "/opt/maven", userSettings: "", localRepository: "" });
     expect(validateSettings({}).languages).toEqual(DEFAULT_LANGUAGES);
   });
 

src/features/settings/languages/LanguagePages.tsx

@@ -1,7 +1,7 @@
 /**
- * Settings › Languages & Frameworks › Go / Java / Node.js / Rust / TypeScript: the
- * toolchain each language's server and run configurations use (applied by
- * `ide-sdk` when language servers start and when run configurations load).
+ * Settings › Languages & Frameworks › Go / Java / Node.js / Rust / TypeScript and
+ * Build Tools › Maven: the toolchain each language's server and run configurations
+ * use (applied by `ide-sdk` when language servers start and when run configurations load).
  */
 import { useId, useMemo } from "react";
 import { IconButton, Input, type SelectOption } from "@/ui";
@@ -16,12 +16,15 @@ function PathInput({
   placeholder,
   hint,
   title,
+  file,
 }: {
   k: string;
   label: string;
   placeholder: string;
   hint?: string;
   title: string;
+  /** Browse for a file instead of a directory. */
+  file?: boolean;
 }) {
   const [value, set] = useProjectSetting<string>(k);
   const id = useId();
@@ -41,7 +44,7 @@ function PathInput({
           size="small"
           title="Browse…"
           onClick={async () => {
-            const p = await choosePath({ directory: true, title, defaultPath: value || undefined });
+            const p = await choosePath({ directory: !file, title, defaultPath: value || undefined });
             if (p) set(p);
           }}
         />
@@ -217,6 +220,19 @@ export function JavaPage() {
   const id = useId();
   return (
     <div className={styles.page}>
+      <Section title="Project JDK">
+        <SdkRow
+          k="languages.java.jdk"
+          label="SDK"
+          kind="jdk"
+          emptyLabel="Auto"
+          emptyDetail="per module, the JDK of its Java version"
+          directory
+          browseTitle="Select JDK Home Directory"
+          aria-label="Project JDK"
+          hint="Compiles and runs the project: the default jdtls runtime, Run/Debug, and JAVA_HOME for Maven and Gradle."
+        />
+      </Section>
       <Section title="Language Server">
         <Row
           label="JVM options"
@@ -237,6 +253,44 @@ export function JavaPage() {
   );
 }
 
+// ---------------------------------------------------------------------------
+// Build Tools › Maven
+
+export function MavenPage() {
+  return (
+    <div className={styles.page}>
+      <Section>
+        <SdkRow
+          k="languages.java.maven.home"
+          label="Maven home path"
+          kind="maven"
+          emptyLabel="Auto"
+          emptyDetail="Maven wrapper, else mvn on PATH"
+          directory
+          browseTitle="Select Maven Home Directory"
+          aria-label="Maven home path"
+          hint="Runs sync, builds and Maven run configurations. A chosen home is used instead of the project's mvnw."
+        />
+        <PathInput
+          k="languages.java.maven.userSettings"
+          label="User settings file"
+          placeholder="~/.m2/settings.xml"
+          title="Select Maven settings.xml"
+          file
+          hint="Passed as -s (mirrors, servers, proxies)."
+        />
+        <PathInput
+          k="languages.java.maven.localRepository"
+          label="Local repository"
+          placeholder="From settings.xml, else ~/.m2/repository"
+          title="Select Local Repository"
+          hint="Passed as -Dmaven.repo.local."
+        />
+      </Section>
+    </div>
+  );
+}
+
 // ---------------------------------------------------------------------------
 // TypeScript
 

src/features/settings/pages/execution.tsx

@@ -1,11 +1,12 @@
 /**
- * Build, Execution, Deployment pages: Console, Debugger (+ Data Views,
+ * Build, Execution, Deployment pages: Maven, Console, Debugger (+ Data Views,
  * Stepping), Python Debugger and Run/Debug. Consumed by the run and debugger
  * features (and `ide-run` for encoding / termination timeout).
  */
 import { WORKFLOW_LIMITS } from "@/platform/workflowSettings";
 import type { SelectOption } from "@/ui";
 import { GlobListEditor, NumberInput, Row } from "../components/Form";
+import { MavenPage } from "../languages/LanguagePages";
 import { useSetting } from "../components/context";
 import type { PageSpec } from "./spec";
 import { Indented, ToggleNumber } from "./workflowControls";
@@ -89,6 +90,15 @@ function TooltipDelayRow() {
 }
 
 export const EXECUTION_PAGES: PageSpec[] = [
+  {
+    id: "build.maven",
+    title: "Maven",
+    group: BUILD_GROUP,
+    // IntelliJ IDEA: Build Tools › Maven, before Console / Debugger.
+    order: 359,
+    keywords: ["maven home", "mvn", "mvnw", "wrapper", "settings.xml", "user settings", "local repository", "m2"],
+    component: MavenPage,
+  },
   {
     id: "build.console",
     title: "Console",

src/features/settings/pages/languages.tsx

@@ -52,7 +52,17 @@ export const LANGUAGE_PAGES: PageSpec[] = [
     title: "Java",
     group: LANGUAGES_GROUP,
     order: 395,
-    keywords: ["jdtls", "jvm options", "vmargs", "lombok", "javaagent", "eclipse jdt"],
+    keywords: [
+      "jdk",
+      "project sdk",
+      "java home",
+      "jdtls",
+      "jvm options",
+      "vmargs",
+      "lombok",
+      "javaagent",
+      "eclipse jdt",
+    ],
     component: JavaPage,
   },
   {

src/platform/languageSettings.ts

@@ -11,7 +11,11 @@ export interface LanguagesValid {
   rust: { toolchain: string; stdlib: string; checkOnSave: boolean; checkCommand: "check" | "clippy"; rustfmtArgs: string };
   go: { goroot: string; gopath: string };
   typescript: { version: string };
-  java: { jdtlsVmArgs: string };
+  java: {
+    jdk: string;
+    jdtlsVmArgs: string;
+    maven: { home: string; userSettings: string; localRepository: string };
+  };
 }
 
 export interface ProjectStructureValid {
@@ -30,7 +34,7 @@ export const DEFAULT_LANGUAGES: LanguagesValid = {
   rust: { toolchain: "", stdlib: "", checkOnSave: true, checkCommand: "check", rustfmtArgs: "" },
   go: { goroot: "", gopath: "" },
   typescript: { version: "bundled" },
-  java: { jdtlsVmArgs: "" },
+  java: { jdk: "", jdtlsVmArgs: "", maven: { home: "", userSettings: "", localRepository: "" } },
 };
 
 export const DEFAULT_PROJECT_STRUCTURE: ProjectStructureValid = {
@@ -76,6 +80,7 @@ export function validateLanguages(raw: unknown): LanguagesValid {
   const go = obj(l.go);
   const ts = obj(l.typescript);
   const java = obj(l.java);
+  const maven = obj(java.maven);
   return {
     python: {
       interpreter: text(py.interpreter, d.python.interpreter),
@@ -94,7 +99,15 @@ export function validateLanguages(raw: unknown): LanguagesValid {
     },
     go: { goroot: text(go.goroot, d.go.goroot), gopath: text(go.gopath, d.go.gopath) },
     typescript: { version: text(ts.version, d.typescript.version) || d.typescript.version },
-    java: { jdtlsVmArgs: text(java.jdtlsVmArgs, d.java.jdtlsVmArgs) },
+    java: {
+      jdk: text(java.jdk, d.java.jdk),
+      jdtlsVmArgs: text(java.jdtlsVmArgs, d.java.jdtlsVmArgs),
+      maven: {
+        home: text(maven.home, d.java.maven.home),
+        userSettings: text(maven.userSettings, d.java.maven.userSettings),
+        localRepository: text(maven.localRepository, d.java.maven.localRepository),
+      },
+    },
   };
 }