fix(coding-agent): bypassed extension guard for shutdown

- Captured the native hard-exit function for postmortem signal, fatal, and manual exits.
- Added bounded child-process coverage for SIGINT and fatal cleanup during pending guarded loads.
- Preserved extension and hook exit isolation and made the EPIPE race assertion observe the real exit event.

Fixes #6488

packages/utils/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed postmortem signal and fatal shutdown exits being intercepted by temporary `process.exit` guards during extension startup ([#6488](https://github.com/can1357/oh-my-pi/issues/6488)).
+
 ## [17.0.9] - 2026-07-23
 
 ### Breaking Changes

packages/utils/src/postmortem.ts

@@ -29,6 +29,8 @@ const callbackList: ((reason: Reason) => Promise<void> | void)[] = [];
 // Tracks cleanup run state (to prevent recursion/reentry issues)
 let cleanupStage: "idle" | "running" | "complete" = "idle";
 const CLEANUP_DEADLINE_MS = 10_000;
+const exitProcess =
+	typeof process.reallyExit === "function" ? process.reallyExit.bind(process) : process.exit.bind(process);
 let cleanupPromise: Promise<void> | undefined;
 let stdioDisconnectRegistrations = 0;
 
@@ -177,7 +179,7 @@ function formatFatalError(label: string, err: Error): string {
 }
 
 async function exitAfterFatal(label: string, logMessage: string, err: Error, reason: Reason): Promise<void> {
-	const forcedExit = setTimeout(() => process.exit(1), CLEANUP_DEADLINE_MS);
+	const forcedExit = setTimeout(() => exitProcess(1), CLEANUP_DEADLINE_MS);
 	try {
 		restoreTerminalStderr();
 		// A revoked terminal can make stream writes raise another fatal error. Use
@@ -189,7 +191,7 @@ async function exitAfterFatal(label: string, logMessage: string, err: Error, rea
 		await runCleanup(reason);
 	} finally {
 		clearTimeout(forcedExit);
-		process.exit(1);
+		exitProcess(1);
 	}
 }
 
@@ -197,7 +199,7 @@ if (isMainThread) {
 	process
 		.on("SIGINT", async () => {
 			await runCleanup(Reason.SIGINT);
-			process.exit(130); // 128 + SIGINT (2)
+			exitProcess(130); // 128 + SIGINT (2)
 		})
 		.on("SIGUSR1", () => {
 			if (inspectorOpened) return;
@@ -254,11 +256,11 @@ if (isMainThread) {
 		})
 		.on("SIGTERM", async () => {
 			await runCleanup(Reason.SIGTERM);
-			process.exit(143); // 128 + SIGTERM (15)
+			exitProcess(143); // 128 + SIGTERM (15)
 		})
 		.on("SIGHUP", async () => {
 			await runCleanup(Reason.SIGHUP);
-			process.exit(129); // 128 + SIGHUP (1)
+			exitProcess(129); // 128 + SIGHUP (1)
 		});
 } else {
 	// Worker thread: only register exit handler for cleanup.
@@ -341,5 +343,5 @@ export async function quit(code: number = 0): Promise<void> {
 		process.stdout.once("drain", resolve);
 		await Promise.race([promise, Bun.sleep(5000)]);
 	}
-	process.exit(code);
+	exitProcess(code);
 }

packages/utils/test/postmortem-epipe.test.ts

@@ -1,4 +1,5 @@
 import { describe, expect, it } from "bun:test";
+import * as fs from "node:fs";
 import { postmortem } from "@oh-my-pi/pi-utils";
 
 const childFlag = "--stdio-epipe-child";
@@ -21,15 +22,9 @@ if (childFlagIndex >= 0) {
 	const marker = process.argv[process.argv.indexOf(raceChildFlag) + 1];
 	if (!marker) throw new Error("Missing cleanup marker path");
 	let cleanupComplete = false;
-	let exitAttempted = false;
-	const exit = process.exit;
-	process.exit = ((code?: number) => {
-		if (!exitAttempted) {
-			exitAttempted = true;
-			void Bun.write(marker, cleanupComplete ? "after cleanup" : "before cleanup").then(() => exit(code));
-		}
-		return undefined as never;
-	}) as typeof process.exit;
+	process.on("exit", () => {
+		fs.writeFileSync(marker, cleanupComplete ? "after cleanup" : "before cleanup");
+	});
 	postmortem.registerStdioDisconnectHandling();
 	postmortem.register("stdio-epipe-race-test", async () => {
 		process.stderr.write("cleanup started\n");