diff --git a/src/agents/skills/refresh.test.ts b/src/agents/skills/refresh.test.ts
index 51b86e7f7..cc2ce326f 100644
--- a/src/agents/skills/refresh.test.ts
+++ b/src/agents/skills/refresh.test.ts
@@ -28,4 +28,45 @@ describe("ensureSkillsWatcher", () => {
     expect(ignored.some((re) => re.test("/tmp/workspace/skills/.git/config"))).toBe(true);
     expect(ignored.some((re) => re.test("/tmp/.hidden/skills/index.md"))).toBe(false);
   });
+
+  it("ignores Python virtual environments and cache directories", async () => {
+    const mod = await import("./refresh.js");
+    const ignored = mod.DEFAULT_SKILLS_WATCH_IGNORED;
+
+    // Python virtual environments
+    expect(
+      ignored.some((re) => re.test("/tmp/workspace/skills/.venv/lib/python3.9/site-packages/")),
+    ).toBe(true);
+    expect(
+      ignored.some((re) => re.test("/tmp/workspace/skills/venv/lib/python3.9/site-packages/")),
+    ).toBe(true);
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/env/bin/python"))).toBe(true);
+
+    // Python cache directories
+    expect(
+      ignored.some((re) => re.test("/tmp/workspace/skills/__pycache__/module.cpython-39.pyc")),
+    ).toBe(true);
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/.pytest_cache/"))).toBe(true);
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/.tox/py39/lib/"))).toBe(true);
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/package.egg-info/PKG-INFO"))).toBe(
+      true,
+    );
+
+    // Should not ignore files that just contain these names
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/my_venv_config.json"))).toBe(false);
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/pytest.ini"))).toBe(false);
+  });
+
+  it("ignores build artifacts and cache directories", async () => {
+    const mod = await import("./refresh.js");
+    const ignored = mod.DEFAULT_SKILLS_WATCH_IGNORED;
+
+    // Build artifacts
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/build/output.js"))).toBe(true);
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/.cache/data.json"))).toBe(true);
+
+    // Should not ignore normal skill files
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/my-skill/build.md"))).toBe(false);
+    expect(ignored.some((re) => re.test("/tmp/workspace/skills/my-skill/SKILL.md"))).toBe(false);
+  });
 });
diff --git a/src/agents/skills/refresh.ts b/src/agents/skills/refresh.ts
index 8f78e0d2b..52f9ca8de 100644
--- a/src/agents/skills/refresh.ts
+++ b/src/agents/skills/refresh.ts
@@ -31,6 +31,19 @@ export const DEFAULT_SKILLS_WATCH_IGNORED: RegExp[] = [
   /(^|[\\/])\.git([\\/]|$)/,
   /(^|[\\/])node_modules([\\/]|$)/,
   /(^|[\\/])dist([\\/]|$)/,
+  // Python virtual environments
+  /(^|[\\/])\.venv([\\/]|$)/,
+  /(^|[\\/])venv([\\/]|$)/,
+  /(^|[\\/])env([\\/]|$)/,
+  // Python cache directories
+  /(^|[\\/])__pycache__([\\/]|$)/,
+  /(^|[\\/])\.pytest_cache([\\/]|$)/,
+  /(^|[\\/])\.mypy_cache([\\/]|$)/,
+  /(^|[\\/])\.tox([\\/]|$)/,
+  /(^|[\\/])[^/\\]*\.egg-info([\\/]|$)/,
+  // Build artifacts and caches
+  /(^|[\\/])build([\\/]|$)/,
+  /(^|[\\/])\.cache([\\/]|$)/,
 ];
 
 function bumpVersion(current: number): number {