fix(linux): add user bin directories to systemd service PATH for skill installation (#1512)

* fix(linux): add user bin directories to systemd service PATH

Fixes #1503

On Linux, the systemd service PATH was hardcoded to only include system
directories (/usr/local/bin, /usr/bin, /bin), causing binaries installed
via npm global with custom prefix or node version managers to not be found.

This adds common Linux user bin directories to the PATH:
- ~/.local/bin (XDG standard, pip, etc.)
- ~/.npm-global/bin (npm custom prefix)
- ~/bin (user's personal bin)
- Node version manager paths (nvm, fnm, volta, asdf)
- ~/.local/share/pnpm (pnpm global)
- ~/.bun/bin (Bun)

User directories are added before system directories so user-installed
binaries take precedence.

🤖 AI-assisted (Claude Opus 4.5 via Clawdbot)
📋 Testing: Existing unit tests pass (7/7)

* test: add comprehensive tests for Linux user bin directory resolution

- Add dedicated tests for resolveLinuxUserBinDirs() function
- Test path ordering (extraDirs > user dirs > system dirs)
- Test buildMinimalServicePath() with HOME set/unset
- Test platform-specific behavior (Linux vs macOS vs Windows)

Test count: 7 → 20 (+13 tests)

* test: add comprehensive tests for Linux user bin directory handling

- Test Linux user directories included when HOME is set
- Test Linux user directories excluded when HOME is missing
- Test path ordering (extraDirs > user dirs > system dirs)
- Test platform-specific behavior (Linux vs macOS vs Windows)
- Test buildMinimalServicePath() with HOME in env

Covers getMinimalServicePathParts() and buildMinimalServicePath()
for all Linux user bin directory edge cases.

Test count: 7 → 16 (+9 tests)

src/daemon/service-env.test.ts

@@ -4,8 +4,98 @@ import {
   buildMinimalServicePath,
   buildNodeServiceEnvironment,
   buildServiceEnvironment,
+  getMinimalServicePathParts,
 } from "./service-env.js";
 
+describe("getMinimalServicePathParts - Linux user directories", () => {
+  it("includes user bin directories when HOME is set on Linux", () => {
+    const result = getMinimalServicePathParts({
+      platform: "linux",
+      home: "/home/testuser",
+    });
+
+    // Should include all common user bin directories
+    expect(result).toContain("/home/testuser/.local/bin");
+    expect(result).toContain("/home/testuser/.npm-global/bin");
+    expect(result).toContain("/home/testuser/bin");
+    expect(result).toContain("/home/testuser/.nvm/current/bin");
+    expect(result).toContain("/home/testuser/.fnm/current/bin");
+    expect(result).toContain("/home/testuser/.volta/bin");
+    expect(result).toContain("/home/testuser/.asdf/shims");
+    expect(result).toContain("/home/testuser/.local/share/pnpm");
+    expect(result).toContain("/home/testuser/.bun/bin");
+  });
+
+  it("excludes user bin directories when HOME is undefined on Linux", () => {
+    const result = getMinimalServicePathParts({
+      platform: "linux",
+      home: undefined,
+    });
+
+    // Should only include system directories
+    expect(result).toEqual(["/usr/local/bin", "/usr/bin", "/bin"]);
+
+    // Should not include any user-specific paths
+    expect(result.some((p) => p.includes(".local"))).toBe(false);
+    expect(result.some((p) => p.includes(".npm-global"))).toBe(false);
+    expect(result.some((p) => p.includes(".nvm"))).toBe(false);
+  });
+
+  it("places user directories before system directories on Linux", () => {
+    const result = getMinimalServicePathParts({
+      platform: "linux",
+      home: "/home/testuser",
+    });
+
+    const userDirIndex = result.indexOf("/home/testuser/.local/bin");
+    const systemDirIndex = result.indexOf("/usr/bin");
+
+    expect(userDirIndex).toBeGreaterThan(-1);
+    expect(systemDirIndex).toBeGreaterThan(-1);
+    expect(userDirIndex).toBeLessThan(systemDirIndex);
+  });
+
+  it("places extraDirs before user directories on Linux", () => {
+    const result = getMinimalServicePathParts({
+      platform: "linux",
+      home: "/home/testuser",
+      extraDirs: ["/custom/bin"],
+    });
+
+    const extraDirIndex = result.indexOf("/custom/bin");
+    const userDirIndex = result.indexOf("/home/testuser/.local/bin");
+
+    expect(extraDirIndex).toBeGreaterThan(-1);
+    expect(userDirIndex).toBeGreaterThan(-1);
+    expect(extraDirIndex).toBeLessThan(userDirIndex);
+  });
+
+  it("does not include Linux user directories on macOS", () => {
+    const result = getMinimalServicePathParts({
+      platform: "darwin",
+      home: "/Users/testuser",
+    });
+
+    // Should not include Linux-specific user dirs even with HOME set
+    expect(result.some((p) => p.includes(".npm-global"))).toBe(false);
+    expect(result.some((p) => p.includes(".nvm"))).toBe(false);
+
+    // Should only include macOS system directories
+    expect(result).toContain("/opt/homebrew/bin");
+    expect(result).toContain("/usr/local/bin");
+  });
+
+  it("does not include Linux user directories on Windows", () => {
+    const result = getMinimalServicePathParts({
+      platform: "win32",
+      home: "C:\\Users\\testuser",
+    });
+
+    // Windows returns empty array (uses existing PATH)
+    expect(result).toEqual([]);
+  });
+});
+
 describe("buildMinimalServicePath", () => {
   it("includes Homebrew + system dirs on macOS", () => {
     const result = buildMinimalServicePath({
@@ -26,6 +116,51 @@ describe("buildMinimalServicePath", () => {
     expect(result).toBe("C:\\\\Windows\\\\System32");
   });
 
+  it("includes Linux user directories when HOME is set in env", () => {
+    const result = buildMinimalServicePath({
+      platform: "linux",
+      env: { HOME: "/home/alice" },
+    });
+    const parts = result.split(path.delimiter);
+
+    // Verify user directories are included
+    expect(parts).toContain("/home/alice/.local/bin");
+    expect(parts).toContain("/home/alice/.npm-global/bin");
+    expect(parts).toContain("/home/alice/.nvm/current/bin");
+
+    // Verify system directories are also included
+    expect(parts).toContain("/usr/local/bin");
+    expect(parts).toContain("/usr/bin");
+    expect(parts).toContain("/bin");
+  });
+
+  it("excludes Linux user directories when HOME is not in env", () => {
+    const result = buildMinimalServicePath({
+      platform: "linux",
+      env: {},
+    });
+    const parts = result.split(path.delimiter);
+
+    // Should only have system directories
+    expect(parts).toEqual(["/usr/local/bin", "/usr/bin", "/bin"]);
+
+    // No user-specific paths
+    expect(parts.some((p) => p.includes("home"))).toBe(false);
+  });
+
+  it("ensures user directories come before system directories on Linux", () => {
+    const result = buildMinimalServicePath({
+      platform: "linux",
+      env: { HOME: "/home/bob" },
+    });
+    const parts = result.split(path.delimiter);
+
+    const firstUserDirIdx = parts.indexOf("/home/bob/.local/bin");
+    const firstSystemDirIdx = parts.indexOf("/usr/local/bin");
+
+    expect(firstUserDirIdx).toBeLessThan(firstSystemDirIdx);
+  });
+
   it("includes extra directories when provided", () => {
     const result = buildMinimalServicePath({
       platform: "linux",

src/daemon/service-env.ts

@@ -17,6 +17,7 @@ import {
 export type MinimalServicePathOptions = {
   platform?: NodeJS.Platform;
   extraDirs?: string[];
+  home?: string;
 };
 
 type BuildServicePathOptions = MinimalServicePathOptions & {
@@ -33,6 +34,31 @@ function resolveSystemPathDirs(platform: NodeJS.Platform): string[] {
   return [];
 }
 
+/**
+ * Resolve common user bin directories for Linux.
+ * These are paths where npm global installs and node version managers typically place binaries.
+ */
+export function resolveLinuxUserBinDirs(home: string | undefined): string[] {
+  if (!home) return [];
+
+  const dirs: string[] = [];
+
+  // Common user bin directories
+  dirs.push(`${home}/.local/bin`); // XDG standard, pip, etc.
+  dirs.push(`${home}/.npm-global/bin`); // npm custom prefix (recommended for non-root)
+  dirs.push(`${home}/bin`); // User's personal bin
+
+  // Node version managers
+  dirs.push(`${home}/.nvm/current/bin`); // nvm with current symlink
+  dirs.push(`${home}/.fnm/current/bin`); // fnm
+  dirs.push(`${home}/.volta/bin`); // Volta
+  dirs.push(`${home}/.asdf/shims`); // asdf
+  dirs.push(`${home}/.local/share/pnpm`); // pnpm global bin
+  dirs.push(`${home}/.bun/bin`); // Bun
+
+  return dirs;
+}
+
 export function getMinimalServicePathParts(options: MinimalServicePathOptions = {}): string[] {
   const platform = options.platform ?? process.platform;
   if (platform === "win32") return [];
@@ -41,12 +67,17 @@ export function getMinimalServicePathParts(options: MinimalServicePathOptions =
   const extraDirs = options.extraDirs ?? [];
   const systemDirs = resolveSystemPathDirs(platform);
 
+  // Add Linux user bin directories (npm global, nvm, fnm, volta, etc.)
+  const linuxUserDirs = platform === "linux" ? resolveLinuxUserBinDirs(options.home) : [];
+
   const add = (dir: string) => {
     if (!dir) return;
     if (!parts.includes(dir)) parts.push(dir);
   };
 
   for (const dir of extraDirs) add(dir);
+  // User dirs first so user-installed binaries take precedence
+  for (const dir of linuxUserDirs) add(dir);
   for (const dir of systemDirs) add(dir);
 
   return parts;
@@ -59,7 +90,10 @@ export function buildMinimalServicePath(options: BuildServicePathOptions = {}):
     return env.PATH ?? "";
   }
 
-  return getMinimalServicePathParts(options).join(path.delimiter);
+  return getMinimalServicePathParts({
+    ...options,
+    home: options.home ?? env.HOME,
+  }).join(path.delimiter);
 }
 
 export function buildServiceEnvironment(params: {