Bust executor prompt cache on workspace SKILL.md layout changes

Add workspace_skills_layout_signature (hash of paths + mtimes + sizes) and fold it into get_executor_prompt_static and manager prebuild cache keys. Add tests for signature drift and cache invalidation.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_oclaw_system_prompt.py

@@ -4,6 +4,7 @@ from pathlib import Path
 
 import pytest
 
+from oclaw.runtime.skills import workspace_skills_layout_signature
 from oclaw.runtime.system_prompt import build_oclaw_executor_system_prompt
 from oclaw.runtime.types import OclawMemoryContext
 from oclaw.platform.persistence.sqlite_store import SqliteStore
@@ -129,6 +130,79 @@ def test_executor_static_prompt_cache_invalidates_on_settings_change(monkeypatch
     assert calls["n"] == 2
 
 
+def test_workspace_skills_layout_signature_changes_on_skill_md_edit(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) -> None:
+    root = tmp_path / "skills_root_sig"
+    (root / "pkg").mkdir(parents=True)
+    f = root / "pkg" / "SKILL.md"
+    f.write_text("---\nname: x\ndescription: d\n---\n", encoding="utf-8")
+    monkeypatch.setenv("AIA_SKILLS_ROOT", str(root))
+    a = workspace_skills_layout_signature()
+    f.write_text("---\nname: x\ndescription: d\n---\n\nbody", encoding="utf-8")
+    b = workspace_skills_layout_signature()
+    assert a != b
+
+
+def test_executor_static_prompt_cache_invalidates_on_workspace_skills_layout_change(monkeypatch: pytest.MonkeyPatch) -> None:
+    from oclaw.runtime import system_prompt as sp
+
+    class DummyStore:
+        def get_setting(self, key: str) -> str:
+            _ = key
+            return ""
+
+    class DummyReg:
+        pass
+
+    calls = {"n": 0}
+    sig = {"v": "layout-a"}
+
+    def _skills_block(**kwargs) -> str:
+        _ = kwargs
+        calls["n"] += 1
+        return "skills-block"
+
+    monkeypatch.setattr(sp, "expert_workspace_signature_token", lambda: ("sig",))
+    monkeypatch.setattr(sp, "workspace_skills_layout_signature", lambda: sig["v"])
+    monkeypatch.setattr(sp, "build_project_context_block", lambda **kwargs: "")
+    monkeypatch.setattr(sp, "build_skills_catalog_block", _skills_block)
+    monkeypatch.setattr(
+        sp,
+        "render_runtime_prompt",
+        lambda prompt_id, variables, strict: f"{prompt_id}\n{variables.get('skills_catalog') or ''}",
+    )
+
+    store = DummyStore()
+    reg = DummyReg()
+    _ = sp.get_executor_prompt_static(
+        store=store,
+        tools=reg,  # type: ignore[arg-type]
+        base_url="",
+        base_system="base",
+        workspace_dir=None,
+        skill_binding_role="generalist",
+    )
+    _ = sp.get_executor_prompt_static(
+        store=store,
+        tools=reg,  # type: ignore[arg-type]
+        base_url="",
+        base_system="base",
+        workspace_dir=None,
+        skill_binding_role="generalist",
+    )
+    assert calls["n"] == 1
+
+    sig["v"] = "layout-b"
+    _ = sp.get_executor_prompt_static(
+        store=store,
+        tools=reg,  # type: ignore[arg-type]
+        base_url="",
+        base_system="base",
+        workspace_dir=None,
+        skill_binding_role="generalist",
+    )
+    assert calls["n"] == 2
+
+
 def test_executor_static_prompt_cache_invalidates_on_skill_role_binding_change(monkeypatch: pytest.MonkeyPatch) -> None:
     from oclaw.runtime import system_prompt as sp