Harden maintainer-preview harness and review fixes

Unify conversational domain routing, preserve artifact completion evidence, replace provisional tool-round prose with terminal synthesis, and resolve verified maintainer review findings across search, frontend module identity, path policy, configuration, and built-in skill startup.

tests/test_embeddings_thread_limit.py

@@ -0,0 +1,51 @@
+import sys
+import types
+
+import pytest
+
+from src import embeddings
+
+
+def _install_fastembed(monkeypatch):
+    calls = []
+    module = types.ModuleType("fastembed")
+
+    class TextEmbedding:
+        def __init__(self, **kwargs):
+            calls.append(kwargs)
+
+    module.TextEmbedding = TextEmbedding
+    monkeypatch.setitem(sys.modules, "fastembed", module)
+    return calls
+
+
+def test_fastembed_threads_default_is_unchanged(monkeypatch, tmp_path):
+    calls = _install_fastembed(monkeypatch)
+    monkeypatch.delenv("FASTEMBED_THREADS", raising=False)
+    monkeypatch.setattr(embeddings, "FASTEMBED_CACHE_DIR", str(tmp_path))
+
+    embeddings.FastEmbedClient(model="test-model")
+
+    assert calls == [{"model_name": "test-model", "cache_dir": str(tmp_path)}]
+
+
+def test_fastembed_threads_can_be_bounded(monkeypatch, tmp_path):
+    calls = _install_fastembed(monkeypatch)
+    monkeypatch.setenv("FASTEMBED_THREADS", "2")
+    monkeypatch.setattr(embeddings, "FASTEMBED_CACHE_DIR", str(tmp_path))
+
+    embeddings.FastEmbedClient(model="test-model")
+
+    assert calls == [
+        {"model_name": "test-model", "cache_dir": str(tmp_path), "threads": 2}
+    ]
+
+
+@pytest.mark.parametrize("value", ["0", "257", "not-a-number"])
+def test_fastembed_threads_rejects_invalid_values(monkeypatch, tmp_path, value):
+    _install_fastembed(monkeypatch)
+    monkeypatch.setenv("FASTEMBED_THREADS", value)
+    monkeypatch.setattr(embeddings, "FASTEMBED_CACHE_DIR", str(tmp_path))
+
+    with pytest.raises(ValueError, match="FASTEMBED_THREADS"):
+        embeddings.FastEmbedClient(model="test-model")