docs(install): preserve agent discovery in services

INSTALL.md

@@ -144,6 +144,21 @@ A checkout has no Rust PTY host until one is put in `bin/`: on a release tag,
 `cargo build --release --manifest-path crates/pty-sidecar/Cargo.toml` builds one. Without either,
 terminals run on Node 18+ where the PC has it, and are mirrored where it has none.
 
+On Linux and macOS, a service manager may start with a smaller `PATH` than an interactive shell.
+Use the existing launcher so Bun, Node and agents installed in `~/.local/bin` are discoverable.
+For example, a systemd unit's `[Service]` section can use:
+
+```ini
+WorkingDirectory=/absolute/path/to/ovis
+ExecStart=/bin/sh /absolute/path/to/ovis/scripts/with-bun.sh run start
+```
+
+Run the service as the user who installed the agents, with that user's `HOME`. The launcher adds
+the usual user-local directories after the existing `PATH`, preserving its command choices.
+If an installed agent such as Grok is missing from the new-session picker, check the service's
+`PATH`: the picker hides agents the server cannot find. Restart the web UI after changing the
+service configuration.
+
 ## 4. Verify
 
 ```bash

changelog.d/source-service-agent-path.md

@@ -0,0 +1,3 @@
+### Maintenance
+- Document the existing launcher for source installs under a service manager, so a restricted
+  `PATH` does not hide user-local agents such as Grok from the new-session picker.

scripts/with-bun.test.ts

@@ -62,6 +62,27 @@ describe.skipIf(process.platform === "win32")("Unix Bun discovery", () => {
     expect(result.out.trim()).toBe("1.4.3");
   });
 
+  it("lets the launched Bun discover Grok in ~/.local/bin with a service's bare PATH", async () => {
+    const bin = join(home, ".bun", "bin");
+    mkdirSync(bin, { recursive: true });
+    symlinkSync(process.execPath, join(bin, "bun"));
+    tool(join(home, ".local", "bin"), "grok", "fixture");
+    const result = await run(["/bin/sh", script, "-e", 'console.log(Bun.which("grok"))']);
+    expect(result.code).toBe(0);
+    expect(result.out.trim()).toBe(join(home, ".local", "bin", "grok"));
+  });
+
+  it("keeps a Grok already on PATH ahead of the user-local fallback", async () => {
+    const bin = join(home, ".bun", "bin");
+    mkdirSync(bin, { recursive: true });
+    symlinkSync(process.execPath, join(bin, "bun"));
+    tool(tools, "grok", "chosen");
+    tool(join(home, ".local", "bin"), "grok", "fallback");
+    const result = await run(["/bin/sh", script, "-e", 'console.log(Bun.which("grok"))']);
+    expect(result.code).toBe(0);
+    expect(result.out.trim()).toBe(join(tools, "grok"));
+  });
+
   it("exits 127 when Bun is missing from PATH and the configured locations", async () => {
     const result = await run(["/bin/sh", script, "x"], { WITH_BUN_EXTRA_DIRS: join(home, "missing") });
     expect(result.code).toBe(127);