diff --git a/src/shims/fs/metadata-cache.test.js b/src/shims/fs/metadata-cache.test.js
index e485a6d..37f85d9 100644
--- a/src/shims/fs/metadata-cache.test.js
+++ b/src/shims/fs/metadata-cache.test.js
@@ -33,28 +33,181 @@ describe("MetadataCache path normalization", () => {
 // -- Operations ------------------------------------------------------
 
 describe("MetadataCache populate and merge", () => {
-  it.todo("populate() clears existing entries");
-  it.todo("merge() preserves existing entries");
-  it.todo("populate then merge -- pre-existing entries survive merge");
+  it("populate() clears existing entries", () => {
+    const cache = new MetadataCache();
+    cache.set("old.md", { type: "file", size: 1 });
+    cache.populate({ "new.md": { type: "file", size: 2 } });
+    expect(cache.has("old.md")).toBe(false);
+    expect(cache.has("new.md")).toBe(true);
+  });
+
+  it("merge() preserves existing entries", () => {
+    const cache = new MetadataCache();
+    cache.set("existing.md", { type: "file", size: 1 });
+    cache.merge({ "added.md": { type: "file", size: 2 } });
+    expect(cache.has("existing.md")).toBe(true);
+    expect(cache.has("added.md")).toBe(true);
+  });
+
+  it("populate then merge -- pre-existing entries survive merge", () => {
+    const cache = new MetadataCache();
+    cache.populate({
+      "a.md": { type: "file", size: 1 },
+      "b.md": { type: "file", size: 2 },
+    });
+    cache.merge({ "c.md": { type: "file", size: 3 } });
+    expect(cache.has("a.md")).toBe(true);
+    expect(cache.has("b.md")).toBe(true);
+    expect(cache.has("c.md")).toBe(true);
+  });
 });
 
 describe("MetadataCache toStat", () => {
-  it.todo("returns correct shape with all expected fields and methods");
-  it.todo("returns null for missing paths");
-  it.todo("constructs dates from zero when mtime/ctime are missing");
+  it("returns correct shape with all expected fields and methods", () => {
+    const cache = new MetadataCache();
+    cache.set("file.md", { type: "file", size: 42, mtime: 1000, ctime: 2000 });
+    const stat = cache.toStat("file.md");
+
+    expect(stat.size).toBe(42);
+    expect(stat.mtimeMs).toBe(1000);
+    expect(stat.ctimeMs).toBe(2000);
+    expect(stat.atimeMs).toBe(1000);
+    expect(stat.birthtimeMs).toBe(2000);
+    expect(stat.mtime).toEqual(new Date(1000));
+    expect(stat.ctime).toEqual(new Date(2000));
+    expect(stat.atime).toEqual(new Date(1000));
+    expect(stat.birthtime).toEqual(new Date(2000));
+    expect(stat.isFile()).toBe(true);
+    expect(stat.isDirectory()).toBe(false);
+    expect(stat.isSymbolicLink()).toBe(false);
+    expect(stat.isBlockDevice()).toBe(false);
+    expect(stat.isCharacterDevice()).toBe(false);
+    expect(stat.isFIFO()).toBe(false);
+    expect(stat.isSocket()).toBe(false);
+  });
+
+  it("returns null for missing paths", () => {
+    const cache = new MetadataCache();
+    expect(cache.toStat("nonexistent.md")).toBe(null);
+  });
+
+  it("constructs dates from zero when mtime/ctime are missing", () => {
+    const cache = new MetadataCache();
+    cache.set("bare.md", { type: "file", size: 1 });
+    const stat = cache.toStat("bare.md");
+
+    expect(stat.mtimeMs).toBe(0);
+    expect(stat.ctimeMs).toBe(0);
+    expect(stat.mtime).toEqual(new Date(0));
+    expect(stat.ctime).toEqual(new Date(0));
+  });
 });
 
 describe("MetadataCache readdir", () => {
-  it.todo("root readdir returns top-level entries");
-  it.todo("nested dir returns only direct children, not grandchildren");
-  it.todo(
-    "readdir of foo does not include foobar entries (prefix false-match)",
-  );
-  it.todo("infers directory type for paths with no direct map entry");
-  it.todo("returns empty array for path with no children");
-  it.todo("returns empty array for nonexistent path");
+  function populated() {
+    const cache = new MetadataCache();
+    cache.populate({
+      "foo/bar.md": { type: "file", size: 1 },
+      "foo/baz.md": { type: "file", size: 2 },
+      "foo/sub/deep.md": { type: "file", size: 3 },
+      "foobar/other.md": { type: "file", size: 4 },
+      "root.md": { type: "file", size: 5 },
+      "docs": { type: "directory", size: 0 },
+    });
+    return cache;
+  }
+
+  it("root readdir returns top-level entries", () => {
+    const cache = populated();
+    const entries = cache.readdir("");
+    const names = entries.map((e) => e.name).sort();
+    expect(names).toEqual(["docs", "foo", "foobar", "root.md"]);
+  });
+
+  it("nested dir returns only direct children, not grandchildren", () => {
+    const cache = populated();
+    const entries = cache.readdir("foo");
+    const names = entries.map((e) => e.name).sort();
+    expect(names).toEqual(["bar.md", "baz.md", "sub"]);
+    expect(names).not.toContain("deep.md");
+  });
+
+  it("readdir of foo does not include foobar entries (prefix false-match)", () => {
+    const cache = populated();
+    const entries = cache.readdir("foo");
+    const names = entries.map((e) => e.name);
+    expect(names).not.toContain("foobar");
+    expect(names).not.toContain("other.md");
+  });
+
+  it("infers directory type for paths with no direct map entry", () => {
+    const cache = populated();
+    const entries = cache.readdir("foo");
+    const sub = entries.find((e) => e.name === "sub");
+    expect(sub).toBeDefined();
+    expect(sub.type).toBe("directory");
+  });
+
+  it("returns empty array for path with no children", () => {
+    const cache = populated();
+    const entries = cache.readdir("docs");
+    expect(entries).toEqual([]);
+  });
+
+  it("returns empty array for nonexistent path", () => {
+    const cache = populated();
+    const entries = cache.readdir("nope/not/here");
+    expect(entries).toEqual([]);
+  });
 });
 
 describe("MetadataCache rename", () => {
-  it.todo("rename file: old path gone, new path present with same metadata");
+  it("rename file: old path gone, new path present with same metadata", () => {
+    const cache = new MetadataCache();
+    const meta = { type: "file", size: 10, mtime: 100 };
+    cache.set("a.md", meta);
+    cache.rename("a.md", "b.md");
+
+    expect(cache.has("a.md")).toBe(false);
+    expect(cache.has("b.md")).toBe(true);
+    expect(cache.get("b.md")).toBe(meta);
+  });
+
+  it("rename directory moves all children", () => {
+    const cache = new MetadataCache();
+    const dirMeta = { type: "directory", size: 0 };
+    const fileMeta = { type: "file", size: 5 };
+    const deepMeta = { type: "file", size: 8 };
+    cache.set("a", dirMeta);
+    cache.set("a/file.md", fileMeta);
+    cache.set("a/sub/deep.md", deepMeta);
+    cache.rename("a", "b");
+
+    expect(cache.has("a")).toBe(false);
+    expect(cache.has("a/file.md")).toBe(false);
+    expect(cache.has("a/sub/deep.md")).toBe(false);
+    expect(cache.get("b")).toBe(dirMeta);
+    expect(cache.get("b/file.md")).toBe(fileMeta);
+    expect(cache.get("b/sub/deep.md")).toBe(deepMeta);
+  });
+
+  it("rename where old and new share a common prefix", () => {
+    const cache = new MetadataCache();
+    const meta = { type: "file", size: 1 };
+    cache.set("a/b", meta);
+    cache.rename("a/b", "a/c");
+
+    expect(cache.has("a/b")).toBe(false);
+    expect(cache.get("a/c")).toBe(meta);
+  });
+
+  it("rename to a deeper nesting level", () => {
+    const cache = new MetadataCache();
+    const meta = { type: "file", size: 1 };
+    cache.set("x", meta);
+    cache.rename("x", "y/z");
+
+    expect(cache.has("x")).toBe(false);
+    expect(cache.get("y/z")).toBe(meta);
+  });
 });