fix(pi-fff): fall back to fff-node when fff-bun cannot be imported

packages/pi-fff/src/sdk.ts

@@ -9,6 +9,22 @@ export type FileFinderStatic = {
 
 let sdkPromise: Promise<{ FileFinder: FileFinderStatic }> | null = null;
 
+const SDK_ORDER: Record<"bun" | "node", readonly [string, string]> = {
+  // fff-bun is TS-source only and cannot be imported by Bun-compiled hosts
+  // (e.g. omp) whose module resolver rejects .ts under node_modules, so the
+  // JS-compiled fff-node is kept as a fallback for every runtime.
+  bun: ["@ff-labs/fff-bun", "@ff-labs/fff-node"],
+  node: ["@ff-labs/fff-node", "@ff-labs/fff-bun"],
+};
+
+// Literal dynamic imports so hosts that statically scan extension graphs
+// (omp's legacy-pi-compat loader) discover and hook both SDK packages;
+// a variable `import(pkg)` would bypass that scan and fail at runtime.
+const SDK_IMPORTS = {
+  "@ff-labs/fff-bun": () => import("@ff-labs/fff-bun"),
+  "@ff-labs/fff-node": () => import("@ff-labs/fff-node"),
+} as const;
+
 function detectRuntime(): "bun" | "node" {
   if (typeof (globalThis as { Bun?: unknown }).Bun !== "undefined") return "bun";
   if (
@@ -19,6 +35,26 @@ function detectRuntime(): "bun" | "node" {
   return "node";
 }
 
+/** Preferred SDK order for the detected runtime. */
+export function sdkCandidates(): readonly [string, string] {
+  return SDK_ORDER[detectRuntime()];
+}
+
+export async function loadFirst(
+  candidates: readonly [string, string],
+  loaders: Record<string, () => Promise<unknown>> = SDK_IMPORTS,
+): Promise<{ FileFinder: FileFinderStatic }> {
+  let lastError: unknown;
+  for (const pkg of candidates) {
+    try {
+      return (await loaders[pkg]()) as { FileFinder: FileFinderStatic };
+    } catch (error) {
+      lastError = error;
+    }
+  }
+  throw lastError;
+}
+
 export function loadSdk(): Promise<{ FileFinder: FileFinderStatic }> {
   if (sdkPromise) return sdkPromise;
 
@@ -34,8 +70,7 @@ export function loadSdk(): Promise<{ FileFinder: FileFinderStatic }> {
   }
 
   // default to node as it seems like default option
-  const pkg = detectRuntime() === "bun" ? "@ff-labs/fff-bun" : "@ff-labs/fff-node";
-  const p = import(pkg) as Promise<{ FileFinder: FileFinderStatic }>;
+  const p = loadFirst(sdkCandidates());
   sdkPromise = p;
   (globalThis as Record<string, unknown>).__fffSdkPromiseGlobal = p;
   return p;

packages/pi-fff/test/sdk.test.ts

@@ -0,0 +1,45 @@
+import { readFileSync } from "node:fs";
+import { describe, expect, test } from "bun:test";
+import { loadFirst, sdkCandidates } from "../src/sdk";
+
+describe("sdkCandidates", () => {
+  test("defaults to bun candidates under a Bun runtime", () => {
+    expect(sdkCandidates()).toEqual(["@ff-labs/fff-bun", "@ff-labs/fff-node"]);
+  });
+});
+
+describe("literal SDK imports", () => {
+  test("both SDK specifiers appear as literal dynamic imports for static graph scans", () => {
+    const source = readFileSync(new URL("../src/sdk.ts", import.meta.url), "utf8");
+    expect(source).toContain('import("@ff-labs/fff-bun")');
+    expect(source).toContain('import("@ff-labs/fff-node")');
+  });
+});
+
+describe("loadFirst", () => {
+  test("prefers the first candidate when both load", async () => {
+    const loaders = {
+      a: () => Promise.resolve({ FileFinder: { create: () => "a" } }),
+      b: () => Promise.resolve({ FileFinder: { create: () => "b" } }),
+    };
+    const mod = await loadFirst(["a", "b"], loaders);
+    expect(mod.FileFinder.create()).toBe("a");
+  });
+
+  test("falls back to the second candidate when the first import fails", async () => {
+    const loaders = {
+      a: () => Promise.reject(new Error("cannot find a")),
+      b: () => Promise.resolve({ FileFinder: { create: () => "b" } }),
+    };
+    const mod = await loadFirst(["a", "b"], loaders);
+    expect(mod.FileFinder.create()).toBe("b");
+  });
+
+  test("throws the last error when every candidate fails", async () => {
+    const loaders = {
+      a: () => Promise.reject(new Error("first failure")),
+      b: () => Promise.reject(new Error("second failure")),
+    };
+    await expect(loadFirst(["a", "b"], loaders)).rejects.toThrow("second failure");
+  });
+});