M14: API runner contract test (verification milestone)

- Add test_api_runner_contract.py: proves API txt2img path invokes ProcessingRunner
- No routing changes: API continues to call process_images (orchestration boundary)
- Monkeypatch CI env + runner.run; call API method directly
- M14_plan.md, M14_toolcalls.md: governance docs

Phase III — Runner & Service Boundary

Made-with: Cursor

test/quality/test_api_runner_contract.py

@@ -0,0 +1,64 @@
+"""M14 contract test: API txt2img path uses ProcessingRunner.
+
+Verifies that the API execution path flows through process_images → runner,
+not direct process_images_inner calls. No routing changes; verification only.
+"""
+from threading import Lock
+
+import pytest
+
+
+def test_api_txt2img_uses_runner(monkeypatch, initialize):
+    """API txt2img path invokes ProcessingRunner when process_images is called."""
+    from fastapi import FastAPI
+
+    from modules.api.api import Api
+    from modules.api import models
+    from modules.processing import Processed
+    from modules.runtime.runner import ProcessingRunner
+
+    called = {"run": False}
+
+    # Force real execution path (bypass CI early return)
+    monkeypatch.setenv("CI", "false")
+
+    # Patch runner to track invocation
+    original_run = ProcessingRunner.run
+
+    def tracking_run(self, request):
+        called["run"] = True
+        return original_run(self, request)
+
+    monkeypatch.setattr(ProcessingRunner, "run", tracking_run)
+
+    # Mock process_images_inner to avoid full pipeline
+    def fake_inner(proc):
+        return Processed(proc, [], seed=-1, info="", comments="")
+
+    import modules.processing as proc_mod
+
+    monkeypatch.setattr(proc_mod, "process_images_inner", fake_inner)
+
+    # Mock model reload and token merging to avoid model/device ops
+    import modules.sd_models as sd_models_mod
+
+    monkeypatch.setattr(sd_models_mod, "reload_model_weights", lambda: None)
+    monkeypatch.setattr(sd_models_mod, "apply_token_merging", lambda m, r: None)
+
+    # Call API method directly (no HTTP)
+    app = FastAPI()
+    api = Api(app, Lock())
+
+    req = models.StableDiffusionTxt2ImgProcessingAPI(
+        prompt="test",
+        steps=1,
+        width=64,
+        height=64,
+    )
+
+    result = api.text2imgapi(req)
+
+    assert called["run"] is True
+    assert result is not None
+    assert hasattr(result, "images")
+    assert hasattr(result, "info")