diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 024306064..9290adc81 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -4,7 +4,7 @@
 
 ### Fixed
 
-- Fixed legacy pi extensions failing extension validation when importing `getPackageDir` or `getProjectDir` from `@earendil-works/pi-coding-agent` (aliased to the legacy shim). The shim only re-exported `getAgentDir`; the two missing path helpers now resolve — `getProjectDir` from `@oh-my-pi/pi-utils` and `getPackageDir` from omp's canonical package-root helper — so extensions like `@gotgenes/pi-permission-system` install and load ([#5968](https://github.com/can1357/oh-my-pi/issues/5968)).
+- Fixed legacy pi extensions failing extension validation when importing `getPackageDir` or `getProjectDir` from `@earendil-works/pi-coding-agent` (aliased to the legacy shim). The shim only re-exported `getAgentDir`; the two missing path helpers now resolve — `getProjectDir` from `@oh-my-pi/pi-utils`, and `getPackageDir` as a string-valued wrapper over omp's canonical package-root helper that falls back to the executable's directory inside `bun --compile` binaries (where the canonical helper returns `undefined`), matching pi's string contract. Extensions like `@gotgenes/pi-permission-system` install and load, and `path.join(getPackageDir(), …)` no longer crashes in the shipped binary ([#5968](https://github.com/can1357/oh-my-pi/issues/5968)).
 
 ## [17.0.4] - 2026-07-18
 
diff --git a/packages/coding-agent/src/extensibility/legacy-pi-coding-agent-shim.ts b/packages/coding-agent/src/extensibility/legacy-pi-coding-agent-shim.ts
index 3e351e589..6542a6481 100644
--- a/packages/coding-agent/src/extensibility/legacy-pi-coding-agent-shim.ts
+++ b/packages/coding-agent/src/extensibility/legacy-pi-coding-agent-shim.ts
@@ -22,8 +22,10 @@ import {
 	getAgentDbPath,
 	getAgentDir,
 	getProjectDir,
+	isCompiledBinary,
 	parseFrontmatter as parseOmpFrontmatter,
 } from "@oh-my-pi/pi-utils";
+import { getPackageDir as getOmpPackageDir } from "../config";
 import type { PromptTemplate } from "../config/prompt-templates";
 import { type SettingPath, Settings } from "../config/settings";
 import { EditTool } from "../edit";
@@ -1336,12 +1338,28 @@ export function readStoredCredential(provider: string): AuthCredential | undefin
 
 // Pi SDK path helpers. `export * from "../index"` above only forwards
 // `getAgentDir`; `getProjectDir` (a `@oh-my-pi/pi-utils` helper) and
-// `getPackageDir` (omp's canonical coding-agent package-root helper, matching
-// pi's "install directory of the coding-agent package" semantics) are absent
-// from that barrel, so legacy extensions importing either fail Bun's static
-// export check during validation (issue #5968).
+// `getPackageDir` are absent from that barrel, so legacy extensions importing
+// either fail Bun's static export check during validation (issue #5968).
 export { getProjectDir } from "@oh-my-pi/pi-utils";
-export { getPackageDir } from "../config";
+
+/**
+ * Coding-agent package install directory, matching pi's string-valued
+ * `getPackageDir()` contract (extensions do `path.join(getPackageDir(), ...)`
+ * to auto-allow bundled docs/resources).
+ *
+ * omp's canonical `getPackageDir()` (`../config`) returns `undefined` inside a
+ * `bun --compile` binary — `import.meta.dir` is `/$bunfs/root` and no owning
+ * `package.json` exists (issue #1423). Returning `undefined` there would crash
+ * every legacy `path.join(getPackageDir(), ...)` at runtime in the shipped
+ * binary, the primary distribution. So fall back to the executable's own
+ * directory in compiled mode, where the binary *is* the install root. The
+ * `PI_PACKAGE_DIR` override and dev/source/npm-dist walk-up still win via the
+ * canonical helper.
+ */
+export function getPackageDir(): string {
+	return getOmpPackageDir() ?? (isCompiledBinary() ? path.dirname(process.execPath) : process.cwd());
+}
+
 export * from "../index";
 export { formatBytes as formatSize } from "../tools/render-utils";
 export { Type } from "./typebox";
diff --git a/packages/coding-agent/test/extensibility/legacy-pi-path-helpers.test.ts b/packages/coding-agent/test/extensibility/legacy-pi-path-helpers.test.ts
index 14e3a3d3a..d2732fe87 100644
--- a/packages/coding-agent/test/extensibility/legacy-pi-path-helpers.test.ts
+++ b/packages/coding-agent/test/extensibility/legacy-pi-path-helpers.test.ts
@@ -1,6 +1,8 @@
-import { describe, expect, it } from "bun:test";
+import { afterEach, describe, expect, it, spyOn, vi } from "bun:test";
 import * as path from "node:path";
+import * as configModule from "@oh-my-pi/pi-coding-agent/config";
 import * as shim from "@oh-my-pi/pi-coding-agent/extensibility/legacy-pi-coding-agent-shim";
+import * as utils from "@oh-my-pi/pi-utils";
 
 // Issue #5968: pi extensions import the SDK path helpers (`getAgentDir`,
 // `getProjectDir`, `getPackageDir`) from `@earendil-works/pi-coding-agent`,
@@ -10,17 +12,37 @@ import * as shim from "@oh-my-pi/pi-coding-agent/extensibility/legacy-pi-coding-
 // error and any importing extension failed validation. These pin the full
 // path-helper surface through the public package specifier.
 describe("legacy shim path helpers", () => {
+	afterEach(() => vi.restoreAllMocks());
+
 	it("exports the three pi SDK path helpers as callable functions", () => {
 		expect(typeof shim.getAgentDir).toBe("function");
 		expect(typeof shim.getProjectDir).toBe("function");
 		expect(typeof shim.getPackageDir).toBe("function");
 	});
 
-	it("getPackageDir resolves the coding-agent package root", () => {
+	it("getPackageDir resolves the coding-agent package root in source mode", () => {
 		// omp's canonical helper returns the package root containing package.json
 		// (pi's "install directory of the coding-agent package" semantics).
 		const dir = shim.getPackageDir();
-		expect(dir).toBeDefined();
-		expect(path.basename(dir as string)).toBe("coding-agent");
+		expect(path.basename(dir)).toBe("coding-agent");
+	});
+
+	// Pi's getPackageDir() is string-valued: extensions do
+	// `path.join(getPackageDir(), ...)`. omp's canonical helper returns
+	// `undefined` inside a `bun --compile` binary (import.meta.dir is
+	// /$bunfs/root, no package.json — issue #1423), which would crash every
+	// such call in the shipped binary. The shim MUST fall back to a real
+	// directory instead of forwarding undefined.
+	it("getPackageDir returns a string even when the canonical helper yields undefined", () => {
+		spyOn(configModule, "getPackageDir").mockReturnValue(undefined);
+		const dir = shim.getPackageDir();
+		expect(typeof dir).toBe("string");
+		expect(dir.length).toBeGreaterThan(0);
+	});
+
+	it("getPackageDir falls back to the executable directory in compiled-binary mode", () => {
+		spyOn(configModule, "getPackageDir").mockReturnValue(undefined);
+		spyOn(utils, "isCompiledBinary").mockReturnValue(true);
+		expect(shim.getPackageDir()).toBe(path.dirname(process.execPath));
 	});
 });