fix(cli): exit cleanly after printing shell completions

Force process termination via `postmortem.quit(0)` in
`Completions.run()` after writing completion scripts to stdout. Loading
all command modules during completion generation leaves open event loop
handles (sockets, timers) that prevent natural process exit, causing
tools like chezmoi to hang.

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed `omp completions <shell>` hanging after writing shell completion scripts to stdout by invoking `postmortem.quit(0)` upon completion. Prevents lingering event loop handles (such as background timers or sockets loaded when inspecting command metadata) from pinning the process and blocking tools like `chezmoi`.
+
 ## [17.3.5] - 2026-08-16
 
 ### Added

packages/coding-agent/src/commands/completions.ts

@@ -5,7 +5,7 @@
  * (see `cli/completion-gen.ts`), so it never drifts from the actual CLI surface.
  */
 
-import { APP_NAME, VERSION } from "@oh-my-pi/pi-utils";
+import { APP_NAME, postmortem, VERSION } from "@oh-my-pi/pi-utils";
 import { Args, type CliConfig, Command, type CommandCtor } from "@oh-my-pi/pi-utils/cli";
 import { completionsHelp as commandHelp } from "../cli/command-help";
 import { buildSpec, generateCompletion, type Shell } from "../cli/completion-gen";
@@ -55,6 +55,7 @@ export default class Completions extends Command {
 		}
 
 		await Bun.write(Bun.stdout, await generateLiveCompletion(shell));
+		await postmortem.quit(0);
 	}
 }
 

packages/coding-agent/test/cli-completions-exit.test.ts

@@ -0,0 +1,21 @@
+import { afterEach, describe, expect, it, spyOn } from "bun:test";
+import { postmortem } from "@oh-my-pi/pi-utils";
+import Completions from "../src/commands/completions";
+
+describe("Completions command exit contract", () => {
+	afterEach(() => {
+		spyOn(postmortem, "quit").mockRestore();
+		spyOn(Bun, "write").mockRestore();
+	});
+
+	it("calls postmortem.quit(0) after writing completion script", async () => {
+		const quitSpy = spyOn(postmortem, "quit").mockResolvedValue(undefined);
+		const writeSpy = spyOn(Bun, "write").mockResolvedValue(0);
+		const config = { bin: "omp", version: "0.0.0", commands: new Map() };
+		const cmd = new Completions(["zsh"], config);
+		await cmd.run();
+
+		expect(writeSpy).toHaveBeenCalled();
+		expect(quitSpy).toHaveBeenCalledWith(0);
+	});
+});