diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 1bff46648..93f794f7f 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -2,6 +2,9 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed all extension loading silently failing on the cross-compiled `omp-darwin-arm64` release binary (downloaded directly or via a Homebrew tap wrapper) because `__computeBunfsPackageRoot` mis-handled `import.meta.dir = "//root/omp-darwin-arm64"`. Bun 1.3.14 reports `<bunfs-root>/<binary-name>` for the compiled entry's `import.meta.dir`, but the pre-fix function joined `metaDir + "packages"` and produced `/root/omp-darwin-arm64/packages` — the binary basename was baked into every bunfs path, so the TypeBox/legacy-pi shims and every `@oh-my-pi/pi-*` package-root override failed `existsSync` validation and `resolveCanonicalPiSpecifier` fell through to a bunfs `Bun.resolveSync` that also could not find the module. The function now detects the bunfs-root + binary-basename shape (`path.basename(path.dirname(metaDir)) === "root"`) and strips the trailing binary segment by slicing the original `metaDir`; the production bunfs shim join path also preserves Bun's bunfs-native `//root` / `B:\~BUN\root` prefix that `path.join` would otherwise collapse. ([#3329](https://github.com/can1357/oh-my-pi/issues/3329))
 ## [16.1.16] - 2026-06-23
 
 ### Breaking Changes
diff --git a/packages/coding-agent/src/extensibility/plugins/legacy-pi-compat.ts b/packages/coding-agent/src/extensibility/plugins/legacy-pi-compat.ts
index dd024c390..bc69f2b43 100644
--- a/packages/coding-agent/src/extensibility/plugins/legacy-pi-compat.ts
+++ b/packages/coding-agent/src/extensibility/plugins/legacy-pi-compat.ts
@@ -93,14 +93,22 @@ const TYPEBOX_SPECIFIER_FILTER = /^(?:@sinclair\/typebox|typebox)$/;
 // so they keep working when on-disk layout differs from the monorepo tree.
 /**
  * Compute the bunfs package root from the compiled binary's `import.meta.dir`
- * (or any stand-in supplied by tests). Bun 1.3 reports the bunfs mount root
- * (`/$bunfs/root` or `<drive>:\~BUN\root`) for imported modules as well as the
- * entrypoint, so the normal path is `<root>/packages`.
+ * (or any stand-in supplied by tests). Bun compiled binaries report one of:
  *
- * The suffix branch preserves correctness if a future Bun release switches to
- * module-specific `import.meta.dir` values inside compiled binaries, matching
- * the source layout:
- * `<bunfs>/packages/coding-agent/src/extensibility/plugins`.
+ * - the bunfs mount root itself — `/$bunfs/root` or `<drive>:\~BUN\root` (Bun
+ *   1.2.x and early 1.3.x). Append `packages` for the canonical layout.
+ * - the bunfs mount root followed by the binary's basename — `//root/<bin>`
+ *   on POSIX or `<drive>:\~BUN\root\<bin>.exe` on Windows (observed on Bun
+ *   1.3.14 with the cross-compiled `omp-darwin-arm64` release asset — issue
+ *   #3329). The trailing segment is stripped so the result still lands on
+ *   `<root>/packages`.
+ * - the module's own source directory if a future Bun release switches to
+ *   module-specific `import.meta.dir` values:
+ *   `<bunfs>/packages/coding-agent/src/extensibility/plugins`.
+ * The bunfs-root-with-binary branch slices the original `metaDir`, and
+ * `bunfsPath` uses a matching double-slash-preserving join, so the bunfs-native
+ * prefix is preserved verbatim — `path.posix.join` collapses `//root` to
+ * `/root`, but Bun's bunfs lookup is keyed on the exact `//root` form.
  *
  * Exported for tests; production callers use `BUNFS_PACKAGE_ROOT` below.
  */
@@ -110,6 +118,10 @@ export function __computeBunfsPackageRoot(metaDir: string, pathImpl: typeof path
 	if (normalizedMetaDir.endsWith(pluginsDirSuffix)) {
 		return pathImpl.resolve(metaDir, "..", "..", "..", "..");
 	}
+	const parent = pathImpl.dirname(metaDir);
+	if (pathImpl.basename(pathImpl.normalize(parent)) === "root") {
+		return `${parent + pathImpl.sep}packages`;
+	}
 	return pathImpl.join(metaDir, "packages");
 }
 
@@ -137,11 +149,31 @@ export function __computeBundledSelfPackageRoot(metaDir: string, pathImpl: typeo
 
 const BUNFS_PACKAGE_ROOT = IS_COMPILED_BINARY ? __computeBunfsPackageRoot(import.meta.dir) : null;
 
+/**
+ * Join a computed bunfs package root with descendants without collapsing
+ * Bun's POSIX `//root` mount prefix.
+ *
+ * Exported for tests; production callers use `bunfsPath` below.
+ */
+export function __joinBunfsPath(root: string, segments: readonly string[], pathImpl: typeof path = path): string {
+	const joined = pathImpl.join(root, ...segments);
+	const doubleRootPrefix = pathImpl.sep + pathImpl.sep;
+	const tripleRootPrefix = doubleRootPrefix + pathImpl.sep;
+	if (
+		root.startsWith(doubleRootPrefix) &&
+		!root.startsWith(tripleRootPrefix) &&
+		!joined.startsWith(doubleRootPrefix)
+	) {
+		return pathImpl.sep + joined;
+	}
+	return joined;
+}
+
 function bunfsPath(...segments: string[]): string {
 	if (!BUNFS_PACKAGE_ROOT) {
 		throw new Error("bunfsPath is only valid in compiled-binary mode");
 	}
-	return path.join(BUNFS_PACKAGE_ROOT, ...segments);
+	return __joinBunfsPath(BUNFS_PACKAGE_ROOT, segments);
 }
 
 function resolveBundledSelfPackageRoot(): string | undefined {
diff --git a/packages/coding-agent/test/extensibility/legacy-pi-bunfs-root.test.ts b/packages/coding-agent/test/extensibility/legacy-pi-bunfs-root.test.ts
index a2e7ebf26..b9a4af64d 100644
--- a/packages/coding-agent/test/extensibility/legacy-pi-bunfs-root.test.ts
+++ b/packages/coding-agent/test/extensibility/legacy-pi-bunfs-root.test.ts
@@ -3,6 +3,7 @@ import * as path from "node:path";
 import {
 	__computeBundledSelfPackageRoot,
 	__computeBunfsPackageRoot,
+	__joinBunfsPath,
 } from "@oh-my-pi/pi-coding-agent/extensibility/plugins/legacy-pi-compat";
 
 // Regression for issue #1514: legacy pi compat shim paths were built from a
@@ -35,6 +36,24 @@ describe("legacy pi compat bunfs root computation (issue #1514)", () => {
 		expect(__computeBunfsPackageRoot(posixMetaDir, path.posix)).toBe("/$bunfs/root/packages");
 	});
 
+	it("preserves the double-slash bunfs prefix through production shim path joins (issue #3329)", () => {
+		// Bun 1.3.14 on the cross-compiled `omp-darwin-arm64` release asset
+		// reports `import.meta.dir` as `//root/omp-darwin-arm64`. The leading
+		// `//` is part of Bun's bunfs identifier, so both the root computation
+		// and the production shim-path join must preserve it.
+		const root = __computeBunfsPackageRoot("//root/omp-darwin-arm64", path.posix);
+		expect(root).toBe("//root/packages");
+		expect(__joinBunfsPath(root, ["coding-agent", "src", "extensibility", "typebox.js"], path.posix)).toBe(
+			"//root/packages/coding-agent/src/extensibility/typebox.js",
+		);
+
+		// `$bunfs`-prefixed variant is also handled.
+		expect(__computeBunfsPackageRoot("/$bunfs/root/omp", path.posix)).toBe("/$bunfs/root/packages");
+		// Windows variant: bunfs mount at `<drive>:\~BUN\root` with the binary
+		// basename appended.
+		expect(__computeBunfsPackageRoot("B:\\~BUN\\root\\omp.exe", path.win32)).toBe("B:\\~BUN\\root\\packages");
+	});
+
 	it("uses the current host path implementation for production calls", () => {
 		const metaDir = path.join("/", "anywhere", "root");
 		expect(__computeBunfsPackageRoot(metaDir)).toBe(path.join("/", "anywhere", "root", "packages"));