fix(adapter): explain non-recursive artifact scan

CHANGELOG.md

@@ -7,6 +7,12 @@ breaking changes may land in a minor release.
 
 ## [Unreleased]
 
+### Fixed
+
+- Explain that unpinned result-artifact scans search only the configured artifact
+  directories themselves, so a nested story spec no longer produces an opaque
+  `no-artifact` breadcrumb (#780).
+
 ## [0.12.0] — 2026-09-20
 
 ### Added

src/bmad_loop/adapters/generic.py

@@ -1850,7 +1850,13 @@ def _frontmatter_fallback(
                 self._note_resultless_stop(
                     task_id,
                     "no-artifact",
-                    "no result artifact newer than session launch under: " + where,
+                    (
+                        f"no result artifact newer than session launch at: {where}"
+                        if only is not None
+                        else "no result artifact newer than session launch directly under: "
+                        + where
+                        + " (subdirectories are not searched)"
+                    ),
                 )
             return None
         if len(candidates) > 1:

tests/test_generic_tmux.py

@@ -1047,6 +1047,25 @@ def test_resultless_stop_breadcrumb_scan_no_artifact(tmp_path, monkeypatch):
     assert str(impl) in crumb["detail"]  # names the searched dirs
 
 
+def test_resultless_stop_breadcrumb_explains_non_recursive_artifact_scan(tmp_path, monkeypatch):
+    """A nested result is outside the legacy scan, so the breadcrumb must say so."""
+    adapter, impl = make_dev_adapter(tmp_path)
+    monkeypatch.setattr(generic, "RESULT_GRACE_S", 0.0)
+    nested = impl / "stories"
+    nested.mkdir()
+    (nested / "spec-3-1-foo.md").write_text(
+        "---\nstatus: done\n---\n\n## Auto Run Result\n\nStatus: done\n",
+        encoding="utf-8",
+    )
+
+    assert adapter._result_json(_dev_handle(), _dev_spec(tmp_path), wait=True) is None
+
+    (crumb,) = _breadcrumbs(adapter)
+    assert crumb["verdict"] == "no-artifact"
+    assert str(impl) in crumb["detail"]
+    assert "subdirectories are not searched" in crumb["detail"]
+
+
 def test_resultless_stop_breadcrumb_stories_pending(tmp_path, monkeypatch):
     adapter, _ = make_dev_adapter(tmp_path)
     monkeypatch.setattr(generic, "RESULT_GRACE_S", 0.0)
@@ -5885,6 +5904,9 @@ def test_expected_spec_breadcrumb_names_the_pinned_path(tmp_path, monkeypatch):
     (crumb,) = _breadcrumbs(adapter)
     assert crumb["verdict"] == "no-artifact"
     assert str(ours) in crumb["detail"]
+    assert "at:" in crumb["detail"]
+    assert "directly under" not in crumb["detail"]
+    assert "subdirectories are not searched" not in crumb["detail"]
     assert "someone-elses" not in crumb["detail"]