feat(durable-effects): implement stat method on nodeRuntime

Adds the stat(path) implementation using @effectionx/fs, matching the
interface added to DurableRuntime. Re-exports StatResult from
durable-effects/runtime.ts and mod.ts. Adds throwing stub and 3 tests
covering file, directory, and missing path cases.

Author: taras

durable-effects/mod.ts

@@ -16,6 +16,7 @@ export type {
   DurableRuntime,
   ResponseHeaders,
   RuntimeFetchResponse,
+  StatResult,
 } from "./runtime.ts";
 
 // ---------------------------------------------------------------------------

durable-effects/node-runtime.test.ts

@@ -67,6 +67,35 @@ describe("nodeRuntime", () => {
     });
   });
 
+  describe("stat", () => {
+    it("returns exists and isFile for an existing file", function* () {
+      const result = yield* runtime.stat("durable-effects/package.json");
+      expect(result).toEqual({
+        exists: true,
+        isFile: true,
+        isDirectory: false,
+      });
+    });
+
+    it("returns exists and isDirectory for an existing directory", function* () {
+      const result = yield* runtime.stat("durable-effects");
+      expect(result).toEqual({
+        exists: true,
+        isFile: false,
+        isDirectory: true,
+      });
+    });
+
+    it("returns all false for a missing path", function* () {
+      const result = yield* runtime.stat("nonexistent-path.txt");
+      expect(result).toEqual({
+        exists: false,
+        isFile: false,
+        isDirectory: false,
+      });
+    });
+  });
+
   describe("glob", () => {
     it("finds files matching a pattern", function* () {
       const results = yield* runtime.glob({

durable-effects/node-runtime.ts

@@ -14,6 +14,7 @@ import { relative, sep } from "node:path";
 import { fetch as effectionFetch } from "@effectionx/fetch";
 import {
   readTextFile as fsReadTextFile,
+  stat as fsStat,
   globToRegExp,
   walk,
 } from "@effectionx/fs";
@@ -62,6 +63,22 @@ export function nodeRuntime(): DurableRuntime {
       return yield* fsReadTextFile(path);
     },
 
+    *stat(path) {
+      try {
+        const s = yield* fsStat(path);
+        return {
+          exists: true,
+          isFile: s.isFile(),
+          isDirectory: s.isDirectory(),
+        };
+      } catch (err: unknown) {
+        if ((err as NodeJS.ErrnoException).code === "ENOENT") {
+          return { exists: false, isFile: false, isDirectory: false };
+        }
+        throw err;
+      }
+    },
+
     *glob(options) {
       const { patterns, root, exclude = [] } = options;
       const results: Array<{ path: string; isFile: boolean }> = [];

durable-effects/runtime.ts

@@ -11,4 +11,5 @@ export type {
   DurableRuntime,
   ResponseHeaders,
   RuntimeFetchResponse,
+  StatResult,
 } from "@effectionx/durable-streams";

durable-effects/stub-runtime.ts

@@ -33,6 +33,9 @@ export function stubRuntime(
     *readTextFile() {
       throw new Error("readTextFile not stubbed");
     },
+    *stat() {
+      throw new Error("stat not stubbed");
+    },
     *glob() {
       throw new Error("glob not stubbed");
     },