fix: resolve PM stamp reads through installation root

pm/environments.py

@@ -107,8 +107,10 @@ def store_root(project_root: Path) -> Path:
             if not store.is_relative_to(root.parent):
                 raise RuntimeError("payload store escapes its root")
             return store
+    from hermes_cli.steward import install_stamp_path
+
     for directory in (root, *root.parents):
-        stamp = directory / "install-stamp.json"
+        stamp = install_stamp_path(directory)
         if stamp.is_file():
             try:
                 data = json.loads(stamp.read_text(encoding="utf-8-sig"))

pm/runtime.py

@@ -61,9 +61,9 @@ def _resident_runtime() -> tuple[Path, Path] | None:
     if payload is not None:
         runtime = payload / "pm-runtime"
     else:
-        from pm.paths import install_root
+        from hermes_cli.steward import install_stamp_path
 
-        stamp_path = install_root() / "install-stamp.json"
+        stamp_path = install_stamp_path(project)
         try:
             stamp = json.loads(stamp_path.read_text(encoding="utf-8-sig"))
         except FileNotFoundError:

tests/hermes_cli/test_source_launcher_publication.py

@@ -15,7 +15,7 @@ from pm.environments import install_state_dir, site_packages
 ROOT = Path(__file__).resolve().parents[2]
 BOOT_FILES = (
     "hermes_bootstrap.py", "hermes_constants.py", "hermes_cli/__init__.py", "hermes_cli/_launchers.py",
-    "pm/environments.py", "hermes_cli/runtime_state.py",
+    "pm/environments.py", "pm/paths.py", "hermes_cli/runtime_state.py",
     "hermes_cli/_early_recovery.py", "hermes_cli/_parser.py",
     "hermes_cli/venv_sync.py", "hermes_cli/steward.py",
     "hermes_cli/stderr_timestamp.py",

tests/pm/test_runtime_entrypoints.py

@@ -55,6 +55,22 @@ def test_ci_dependency_phase_uses_isolated_runtime(tmp_path, monkeypatch):
     assert all(arguments["explicit"] for _, arguments in calls)
 
 
+def test_store_root_reads_executing_trees_canonical_install_stamp(tmp_path, monkeypatch):
+    from pm import environments, paths
+
+    project = tmp_path / "source"
+    project.mkdir()
+    package = tmp_path / "package"
+    package.mkdir()
+    runtime = tmp_path / "packaged-tools"
+    (package / "install-stamp.json").write_text(json.dumps({"runtimeDir": str(runtime)}))
+    monkeypatch.setattr(paths, "repo_root", lambda: project)
+    monkeypatch.setenv("HERMES_INSTALL_ROOT", str(package))
+    monkeypatch.delenv("HERMES_RUNTIME_DIR", raising=False)
+
+    assert environments.store_root(project) == runtime
+
+
 @pytest.mark.parametrize("distribution", ["nix", "docker"])
 def test_packaged_runtime_uses_explicit_stamp_without_tool_downloads(tmp_path, monkeypatch, distribution):
     from pm import runtime, paths