fix(tiny): isolated tiny model worker in subprocess to skip onnxruntime napi crash

Moved the tiny title/memory worker from a Bun Worker thread into a child process spawned via Bun.spawn IPC. The agent CLI gains a hidden --tiny-worker dispatch the parent invokes through process.execPath; the parent SIGKILLs the child on dispose so onnxruntime-node's NAPI finalizer never runs in any address space the agent owns. On Windows that finalizer was segfaulting Bun at shutdown after the tiny title model loaded (issue #1606). Drops the now-dead 'close'/'closed' handshake and the unused parentPort bootstrap, and removes tiny/worker.ts from --compile worker entries in both build scripts plus the regression test that pinned them.

Fixes #1606

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed `omp` segfaulting on exit on Windows after the tiny title/memory model loaded `onnxruntime-node` (issue [#1606](https://github.com/can1357/oh-my-pi/issues/1606)). The tiny model now runs in a Bun subprocess instead of a Worker thread, so the NAPI finalizer that crashes during shutdown never executes in the agent's address space; the subprocess is `SIGKILL`'d on dispose to skip every native destructor on every platform.
+
 ## [15.7.4] - 2026-05-31
 
 ### Removed

packages/coding-agent/scripts/build-binary.ts

@@ -56,7 +56,6 @@ async function main(): Promise<void> {
 					"../stats/src/sync-worker.ts",
 					"./src/tools/browser/tab-worker-entry.ts",
 					"./src/eval/js/worker-entry.ts",
-					"./src/tiny/worker.ts",
 					// Legacy pi-* extension compat entrypoints served by
 					// `legacy-pi-compat.ts`. These are reached via computed bunfs paths
 					// (which `--compile`'s static analyzer cannot trace), so each must be

packages/coding-agent/src/cli.ts

@@ -54,12 +54,60 @@ async function runSmokeTest(): Promise<void> {
 	process.stdout.write("smoke-test: ok\n");
 }
 
+/**
+ * Hidden subcommand that boots the tiny-model worker inside this process
+ * over the parent's IPC channel. The agent's main process spawns the same
+ * binary with this flag so `onnxruntime-node` (loaded transitively by
+ * `@huggingface/transformers`) lives in a child address space. The parent
+ * `SIGKILL`s the child on shutdown so the NAPI finalizer never runs in
+ * either process — that finalizer segfaults Bun on Windows (issue #1606).
+ */
+async function runTinyWorker(): Promise<void> {
+	const { startTinyTitleWorker } = await import("./tiny/worker");
+	const { promise: shuttingDown, resolve: shutdown } = Promise.withResolvers<void>();
+	const send = (message: unknown): void => {
+		// `process.send` only exists when spawned with an IPC channel; the
+		// parent always spawns us that way. If it's missing, the parent
+		// vanished and there's no one to talk to.
+		const sender = (process as NodeJS.Process & { send?: (m: unknown) => boolean }).send;
+		if (!sender) {
+			shutdown();
+			return;
+		}
+		try {
+			sender.call(process, message);
+		} catch {
+			shutdown();
+		}
+	};
+	startTinyTitleWorker({
+		send,
+		onMessage(handler) {
+			const wrap = (data: unknown): void => handler(data as never);
+			process.on("message", wrap);
+			return () => {
+				process.off("message", wrap);
+			};
+		},
+	});
+	// Parent went away (crashed, SIGKILL, etc.) — commit suicide so we don't
+	// linger as an orphan. SIGKILL via `process.kill` keeps us symmetrical
+	// with the parent's hard-kill on shutdown: skip every JS/native finalizer.
+	process.on("disconnect", () => shutdown());
+	await shuttingDown;
+	process.kill(process.pid, "SIGKILL");
+}
+
 /** Run the CLI with the given argv (no `process.argv` prefix). */
 export async function runCli(argv: string[]): Promise<void> {
 	if (argv[0] === "--smoke-test") {
 		await runSmokeTest();
 		return;
 	}
+	if (argv[0] === "--tiny-worker") {
+		await runTinyWorker();
+		return;
+	}
 	// --help and --version are handled by run() directly, don't rewrite those.
 	// Everything else that isn't a known subcommand routes to "launch".
 	const first = argv[0];

packages/coding-agent/src/tiny/title-client.ts

@@ -1,4 +1,6 @@
+import * as path from "node:path";
 import { $env, isCompiledBinary, logger } from "@oh-my-pi/pi-utils";
+import type { Subprocess } from "bun";
 import { settings } from "../config/settings";
 import { tinyModelDeviceSettingToEnv } from "./device";
 import { tinyModelDtypeSettingToEnv } from "./dtype";
@@ -12,6 +14,14 @@ import {
 } from "./models";
 import type { TinyTitleProgressEvent, TinyTitleWorkerInbound, TinyTitleWorkerOutbound } from "./title-protocol";
 
+/**
+ * Abstraction over the tiny-model subprocess. Modelled as a worker interface
+ * so existing callers (titles, memory completions, downloads) compose the
+ * same way; the runtime implementation is a Bun child process so
+ * `onnxruntime-node`'s NAPI finalizer never runs inside the main agent
+ * address space — that destructor segfaults Bun on Windows during shutdown
+ * (issue #1606).
+ */
 interface WorkerHandle {
 	send(message: TinyTitleWorkerInbound): void;
 	onMessage(handler: (message: TinyTitleWorkerOutbound) => void): () => void;
@@ -31,6 +41,12 @@ export interface TinyTitleDownloadOptions {
 
 const SMOKE_TEST_TIMEOUT_MS = 5_000;
 
+/**
+ * Hidden subcommand on the main CLI that boots the tiny-model worker in the
+ * spawned subprocess. Kept in sync with the dispatch in `cli.ts`.
+ */
+export const TINY_WORKER_ARG = "--tiny-worker";
+
 function readTinyModelSetting(path: "providers.tinyModelDevice" | "providers.tinyModelDtype"): string | undefined {
 	try {
 		const value = settings.get(path);
@@ -66,49 +82,108 @@ export function tinyWorkerEnvOverlay(
 }
 
 /**
- * Env handed to the tiny-model worker. The `PI_TINY_DEVICE` / `PI_TINY_DTYPE` env
- * vars win; otherwise the persisted `providers.tinyModelDevice` /
- * `providers.tinyModelDtype` settings are mapped onto those vars so the worker's
- * env-based resolution picks them up. Resolved once at spawn (pipelines are cached).
+ * Env handed to the tiny-model subprocess. The `PI_TINY_DEVICE` / `PI_TINY_DTYPE`
+ * env vars win; otherwise the persisted `providers.tinyModelDevice` /
+ * `providers.tinyModelDtype` settings are mapped onto those vars so the
+ * subprocess's env-based resolution picks them up. Resolved once at spawn
+ * (pipelines are cached for the lifetime of the subprocess).
  */
-function tinyWorkerEnv(): Record<string, string> | undefined {
+function tinyWorkerEnv(): Record<string, string> {
 	const overlay = tinyWorkerEnvOverlay(
 		$env,
 		readTinyModelSetting("providers.tinyModelDevice"),
 		readTinyModelSetting("providers.tinyModelDtype"),
 	);
-	if (Object.keys(overlay).length === 0) return undefined;
-	return { ...($env as Record<string, string>), ...overlay };
+	const base = $env as Record<string, string | undefined>;
+	const merged: Record<string, string> = {};
+	for (const key in base) {
+		const value = base[key];
+		if (typeof value === "string") merged[key] = value;
+	}
+	for (const key in overlay) merged[key] = overlay[key];
+	return merged;
 }
 
-export function createTinyTitleWorker(): Worker {
-	const env = tinyWorkerEnv();
-	const options: WorkerOptions = env ? { type: "module", env } : { type: "module" };
-	return isCompiledBinary()
-		? new Worker("./packages/coding-agent/src/tiny/worker.ts", options)
-		: new Worker(new URL("./worker.ts", import.meta.url).href, options);
+/**
+ * Resolve the argv used to relaunch the agent CLI into tiny-worker mode. In a
+ * compiled binary the entry point is the binary itself; in dev/source the
+ * spawned `bun` needs the absolute path to `cli.ts` so it can resolve module
+ * imports against the on-disk source tree.
+ */
+function tinyWorkerSpawnCmd(): string[] {
+	if (isCompiledBinary()) return [process.execPath, TINY_WORKER_ARG];
+	const cliPath = path.resolve(import.meta.dir, "..", "cli.ts");
+	return [process.execPath, cliPath, TINY_WORKER_ARG];
 }
 
-function wrapBunWorker(worker: Worker): WorkerHandle {
-	(worker as Worker & { unref?: () => void }).unref?.();
+interface SpawnedSubprocess {
+	proc: Subprocess<"ignore", "inherit", "inherit">;
+	inbound: Set<(message: TinyTitleWorkerOutbound) => void>;
+	errors: Set<(error: Error) => void>;
+}
+
+/**
+ * Spawn the tiny-model worker as a subprocess. Exported for tests and the
+ * smoke probe; production callers go through {@link spawnTinyTitleWorker}
+ * which wraps the result in a {@link WorkerHandle}.
+ */
+export function createTinyTitleSubprocess(): SpawnedSubprocess {
+	const inbound = new Set<(message: TinyTitleWorkerOutbound) => void>();
+	const errors = new Set<(error: Error) => void>();
+	const proc = Bun.spawn({
+		cmd: tinyWorkerSpawnCmd(),
+		env: tinyWorkerEnv(),
+		stdin: "ignore",
+		stdout: "inherit",
+		stderr: "inherit",
+		serialization: "advanced",
+		windowsHide: true,
+		ipc(message) {
+			for (const handler of inbound) handler(message as TinyTitleWorkerOutbound);
+		},
+		onExit(_proc, exitCode, signalCode) {
+			if (exitCode === 0 || exitCode === null) return;
+			const signalSuffix = signalCode ? ` (signal ${signalCode})` : "";
+			const err = new Error(`tiny model subprocess exited with code ${exitCode}${signalSuffix}`);
+			for (const handler of errors) handler(err);
+		},
+	});
+	// Don't keep the parent event loop alive on account of an idle worker; the
+	// agent dispose path calls `terminate()` explicitly when shutting down.
+	proc.unref();
+	return { proc, inbound, errors };
+}
+
+function wrapSubprocess({ proc, inbound, errors }: SpawnedSubprocess): WorkerHandle {
 	return {
 		send(message) {
-			worker.postMessage(message);
+			try {
+				proc.send(message);
+			} catch (error) {
+				logger.debug("tiny-title: send to subprocess failed", {
+					error: error instanceof Error ? error.message : String(error),
+				});
+			}
 		},
 		onMessage(handler) {
-			const wrap = (event: MessageEvent): void => handler(event.data as TinyTitleWorkerOutbound);
-			worker.addEventListener("message", wrap);
-			return () => worker.removeEventListener("message", wrap);
+			inbound.add(handler);
+			return () => inbound.delete(handler);
 		},
 		onError(handler) {
-			const wrap = (event: ErrorEvent): void => {
-				handler(event.error instanceof Error ? event.error : new Error(event.message || "tiny title worker error"));
-			};
-			worker.addEventListener("error", wrap);
-			return () => worker.removeEventListener("error", wrap);
+			errors.add(handler);
+			return () => errors.delete(handler);
 		},
 		async terminate() {
-			worker.terminate();
+			// SIGKILL: the whole point of the subprocess isolation is that the
+			// parent never runs `onnxruntime-node`'s NAPI finalizer. A polite
+			// SIGTERM lets the subprocess try to clean up, which is exactly the
+			// codepath that crashes Bun on Windows. Hard-kill instead — the
+			// model lives in process memory and the OS reclaims everything.
+			try {
+				proc.kill("SIGKILL");
+			} catch {
+				// Already gone.
+			}
 		},
 	};
 }
@@ -126,10 +201,6 @@ function spawnInlineUnavailableWorker(error: unknown): WorkerHandle {
 					emit({ type: "pong", id: message.id });
 					return;
 				}
-				if (message.type === "close") {
-					emit({ type: "closed" });
-					return;
-				}
 				emit({ type: "error", id: message.id, error: errorMessage });
 			});
 		},
@@ -148,9 +219,9 @@ function spawnInlineUnavailableWorker(error: unknown): WorkerHandle {
 
 function spawnTinyTitleWorker(): WorkerHandle {
 	try {
-		return wrapBunWorker(createTinyTitleWorker());
+		return wrapSubprocess(createTinyTitleSubprocess());
 	} catch (error) {
-		logger.warn("Tiny title Worker spawn failed; local titles disabled", {
+		logger.warn("Tiny title worker spawn failed; local titles disabled", {
 			error: error instanceof Error ? error.message : String(error),
 		});
 		return spawnInlineUnavailableWorker(error);
@@ -293,9 +364,9 @@ export class TinyTitleClient {
 		}
 		this.#pending.clear();
 		try {
-			worker?.send({ type: "close" });
+			await worker?.terminate();
 		} catch {
-			// Worker may already be gone.
+			// Already gone.
 		}
 	}
 
@@ -317,7 +388,6 @@ export class TinyTitleClient {
 			this.#emitProgress(message.event);
 			return;
 		}
-		if (message.type === "closed") return;
 		if (message.type === "pong") return;
 
 		const pending = this.#pending.get(message.id);
@@ -371,25 +441,25 @@ export async function smokeTestTinyTitleWorker({
 }: {
 	timeoutMs?: number;
 } = {}): Promise<void> {
-	const worker = createTinyTitleWorker();
+	const handle = wrapSubprocess(createTinyTitleSubprocess());
 	const { promise, resolve, reject } = Promise.withResolvers<void>();
 	const timer = setTimeout(() => reject(new Error(`tiny title worker did not pong within ${timeoutMs}ms`)), timeoutMs);
-	worker.onmessage = (event: MessageEvent<TinyTitleWorkerOutbound>) => {
-		const message = event.data;
+	const unsubscribeMessage = handle.onMessage(message => {
 		if (message.type === "pong") {
 			resolve();
 			return;
 		}
+		if (message.type === "log") return;
 		reject(new Error(`tiny title worker: expected pong, got ${JSON.stringify(message)}`));
-	};
-	worker.onerror = (event: ErrorEvent) => {
-		reject(event.error instanceof Error ? event.error : new Error(event.message || "tiny title worker error"));
-	};
+	});
+	const unsubscribeError = handle.onError(reject);
 	try {
-		worker.postMessage({ type: "ping", id: "smoke" } satisfies TinyTitleWorkerInbound);
+		handle.send({ type: "ping", id: "smoke" } satisfies TinyTitleWorkerInbound);
 		await promise;
 	} finally {
 		clearTimeout(timer);
-		worker.terminate();
+		unsubscribeMessage();
+		unsubscribeError();
+		await handle.terminate();
 	}
 }

packages/coding-agent/src/tiny/title-protocol.ts

@@ -31,8 +31,7 @@ export type TinyTitleWorkerInbound =
 	| { type: "ping"; id: string }
 	| { type: "generate"; id: string; modelKey: TinyTitleLocalModelKey; message: string }
 	| { type: "complete"; id: string; modelKey: TinyLocalModelKey; prompt: string; maxTokens?: number }
-	| { type: "download"; id: string; modelKey: TinyLocalModelKey }
-	| { type: "close" };
+	| { type: "download"; id: string; modelKey: TinyLocalModelKey };
 
 export type TinyTitleWorkerOutbound =
 	| { type: "pong"; id: string }
@@ -41,11 +40,17 @@ export type TinyTitleWorkerOutbound =
 	| { type: "downloaded"; id: string }
 	| { type: "error"; id: string; error: string }
 	| { type: "progress"; id: string; event: TinyTitleProgressEvent }
-	| { type: "log"; level: "debug" | "warn" | "error"; msg: string; meta?: Record<string, unknown> }
-	| { type: "closed" };
+	| { type: "log"; level: "debug" | "warn" | "error"; msg: string; meta?: Record<string, unknown> };
 
+/**
+ * Wire transport between the parent (`TinyTitleClient`) and the tiny-model
+ * subprocess. The parent owns the subprocess lifecycle (graceful work, hard
+ * kill on shutdown); the protocol therefore carries no explicit close
+ * handshake — once the parent decides to terminate, it signals the OS to
+ * reap the child so `onnxruntime-node`'s NAPI finalizer never runs in any
+ * shared address space. See `title-client.ts` for the spawn/kill glue.
+ */
 export interface TinyTitleTransport {
 	send(message: TinyTitleWorkerOutbound): void;
 	onMessage(handler: (message: TinyTitleWorkerInbound) => void): () => void;
-	close(): void;
 }

packages/coding-agent/src/tiny/worker.ts

@@ -1,7 +1,6 @@
 import * as fs from "node:fs/promises";
 import { createRequire } from "node:module";
 import * as path from "node:path";
-import { parentPort } from "node:worker_threads";
 import type {
 	ProgressInfo,
 	TextGenerationPipeline,
@@ -20,12 +19,7 @@ import {
 	type TinyTitleLocalModelSpec,
 } from "./models";
 import { formatTitleUserMessage, normalizeGeneratedTitle } from "./text";
-import type {
-	TinyTitleProgressEvent,
-	TinyTitleTransport,
-	TinyTitleWorkerInbound,
-	TinyTitleWorkerOutbound,
-} from "./title-protocol";
+import type { TinyTitleProgressEvent, TinyTitleTransport, TinyTitleWorkerInbound } from "./title-protocol";
 
 const TITLE_PREFILL = "<title>";
 const TITLE_CLOSE = "</title>";
@@ -497,16 +491,6 @@ async function generateCompletion(
 	return generated === "" ? null : generated;
 }
 
-function releasePipelines(): void {
-	// Intentionally NOT calling `pipeline.dispose()`. transformers.js disposes the
-	// underlying onnxruntime InferenceSession, freeing native memory that Bun's
-	// worker/NAPI teardown then frees a second time — a double-free that aborts the
-	// process on quit ("malloc: pointer being freed was not allocated" /
-	// "NAPI FATAL ERROR"). The worker is torn down immediately after `close`, so the
-	// OS reclaims the model memory regardless; skipping dispose avoids the crash.
-	pipelines.clear();
-}
-
 function enqueueRequest(
 	transport: TinyTitleTransport,
 	request: Extract<TinyTitleWorkerInbound, { type: "generate" | "complete" | "download" }>,
@@ -555,33 +539,6 @@ export function startTinyTitleWorker(transport: TinyTitleTransport): void {
 			transport.send({ type: "pong", id: message.id });
 			return;
 		}
-		if (message.type === "close") {
-			releasePipelines();
-			transport.send({ type: "closed" });
-			transport.close();
-			return;
-		}
 		enqueueRequest(transport, message);
 	});
 }
-
-if (!parentPort) throw new Error("tiny-title-worker: missing parentPort");
-
-const port = parentPort;
-const transport: TinyTitleTransport = {
-	send: (message: TinyTitleWorkerOutbound) => port.postMessage(message),
-	onMessage: handler => {
-		const wrap = (data: unknown): void => handler(data as TinyTitleWorkerInbound);
-		port.on("message", wrap);
-		return () => port.off("message", wrap);
-	},
-	close: () => {
-		try {
-			port.close();
-		} catch {
-			// Already closed.
-		}
-	},
-};
-
-startTinyTitleWorker(transport);

packages/coding-agent/test/issue-1150-repro.test.ts

@@ -35,7 +35,6 @@ describe("issue #1150 — release-build script must list all worker --compile en
 		"./packages/stats/src/sync-worker.ts",
 		"./packages/coding-agent/src/tools/browser/tab-worker-entry.ts",
 		"./packages/coding-agent/src/eval/js/worker-entry.ts",
-		"./packages/coding-agent/src/tiny/worker.ts",
 	];
 
 	it("scripts/ci-release-build-binaries.ts lists every worker as an explicit --compile entrypoint", async () => {
@@ -56,7 +55,6 @@ describe("issue #1150 — release-build script must list all worker --compile en
 			"../stats/src/sync-worker.ts",
 			"./src/tools/browser/tab-worker-entry.ts",
 			"./src/eval/js/worker-entry.ts",
-			"./src/tiny/worker.ts",
 		];
 		const source = await Bun.file(devScriptPath).text();
 		for (const entry of devEntrypoints) {

packages/coding-agent/test/issue-1606-repro.test.ts

@@ -0,0 +1,41 @@
+/**
+ * Regression for https://github.com/can1357/oh-my-pi/issues/1606
+ *
+ * On Windows, `onnxruntime-node`'s NAPI finalizer segfaults Bun during
+ * shutdown after `@huggingface/transformers` has loaded a tiny model in a
+ * Worker thread. The agent used to host the tiny-model worker as a Worker
+ * inside its own process; tearing the worker down ran the native destructor
+ * in the parent's address space and crashed the CLI on exit.
+ *
+ * The fix relocates the worker to a child process: `title-client.ts` spawns
+ * `process.execPath … --tiny-worker`, `cli.ts` dispatches that flag into
+ * `runTinyWorker`, and the parent `SIGKILL`s the child on dispose so the
+ * native finalizer never runs in either address space. These tests pin the
+ * three pieces of that contract so a future refactor cannot quietly land
+ * the original crash again.
+ */
+import { describe, expect, it } from "bun:test";
+import { smokeTestTinyTitleWorker, TINY_WORKER_ARG } from "../src/tiny/title-client";
+
+describe("issue #1606 — tiny model lives in an isolated subprocess", () => {
+	it("ping/pongs through the spawned worker subprocess and tears it down cleanly", async () => {
+		// `smokeTestTinyTitleWorker` is the runtime probe wired into
+		// `omp --smoke-test`: it spawns the worker subprocess via
+		// `Bun.spawn`, sends a ping over the IPC channel, awaits the pong,
+		// then SIGKILLs the child. If anyone reverts the worker to an
+		// in-process `new Worker(...)` thread or drops the `--tiny-worker`
+		// CLI dispatch, the spawn either picks up the wrong entrypoint or
+		// the ping never round-trips, and this test fails.
+		await expect(smokeTestTinyTitleWorker({ timeoutMs: 15_000 })).resolves.toBeUndefined();
+	}, 30_000);
+
+	it("CLI dispatches the flag that `title-client.ts` passes to the spawned child", async () => {
+		// `tinyWorkerSpawnCmd()` and the cli switch must agree on the exact
+		// flag, character-for-character — the spawned `bun`/binary sees only
+		// `argv` and there is no fallback path that "re-routes" the worker
+		// on misnamed flags. Pin the spelling on both ends.
+		const cliSource = await Bun.file(new URL("../src/cli.ts", import.meta.url)).text();
+		expect(cliSource).toContain(`argv[0] === "${TINY_WORKER_ARG}"`);
+		expect(cliSource).toContain("runTinyWorker");
+	});
+});

scripts/ci-release-build-binaries.ts

@@ -27,7 +27,6 @@ const workerEntrypoints = [
 	"./packages/stats/src/sync-worker.ts",
 	"./packages/coding-agent/src/tools/browser/tab-worker-entry.ts",
 	"./packages/coding-agent/src/eval/js/worker-entry.ts",
-	"./packages/coding-agent/src/tiny/worker.ts",
 ];
 const isDryRun = process.argv.includes("--dry-run");
 const targets: BinaryTarget[] = [