test: cover casting constraints

CHANGELOG.md

@@ -46,6 +46,8 @@ Follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) · versioned wi
   duplicate manifest entries, and top-level declaration collisions before bundling.
 - **Provider Boundary Regression Coverage.** Added deterministic tests for STT backend normalization and ComfyUI
   workflow submission, prompt injection, polling, seed derivation, and image retrieval.
+- **Casting Constraint Coverage.** Added deterministic regression coverage proving casting filters invented voice IDs
+  and avoids unnecessary duplicate assignments when distinct catalogue voices are available.
 - **STT Cancellation Safety.** Queued transcription cancels before consuming the single STT slot, and timed-out
   requests keep the device slot held until the underlying worker actually exits.
 - **Credential Boundary Review.** Provider credentials are now documented as server-only; only the explicitly

TODO.md

@@ -165,7 +165,7 @@ the first block before investing in architecture or polish.
 ### Automated tests
 
 - [ ] Character parsing and phantom-speaker prevention.
-- [ ] Voice-matching constraints.
+- [x] Voice-matching constraints reject invented voice IDs and avoid unnecessary duplicate assignments.
 - [ ] Profile-completeness counting.
 - [x] Rating persistence.
 - [x] STT endpoint normalization and backend-response shape handling.

VERSION

@@ -1 +1 @@
-1.23.2
+1.23.3

tests/test_conversation.py

@@ -19,6 +19,8 @@ from routes.conversation import (
     _fallback_attribute_response,
     _bundled_comfyui_workflow,
     _comfyui_run,
+    _CastJobRequest,
+    match_characters_voices,
 )
 
 
@@ -106,6 +108,27 @@ class AttributionParserTests(unittest.TestCase):
         self.assertEqual(submitted["2"]["inputs"]["text"], "new prompt")
         self.assertNotEqual(submitted["5"]["inputs"]["seed"], 0)
 
+    def test_voice_matching_rejects_invented_and_unnecessarily_duplicate_ids(self):
+        from unittest.mock import patch
+
+        class ResponseStub:
+            status_code = 200
+            ok = True
+            text = ""
+            def raise_for_status(self):
+                return None
+            def json(self):
+                return {"choices": [{"message": {"content": json.dumps({"assignments": [
+                    {"name": "A", "voice_id": "v1", "reason": "match"},
+                    {"name": "B", "voice_id": "invented", "reason": "bad"},
+                    {"name": "C", "voice_id": "v1", "reason": "duplicate"},
+                ]})}}]}
+
+        data = {"names": ["A", "B", "C"], "voices": [{"id": "v1", "gender": "F"}, {"id": "v2", "gender": "M"}], "script": "short", "llm_url": "http://llm/v1"}
+        with patch("routes.conversation.requests.post", return_value=ResponseStub()):
+            result = __import__("asyncio").run(match_characters_voices(_CastJobRequest(data, {})))
+        self.assertEqual([item["voice_id"] for item in result["assignments"]], ["v1"])
+
     def test_consistent_image_job_can_be_cancelled(self):
         from fastapi.testclient import TestClient
         from server import app