fix: surface bounded GPU admission failures

tests/test_app_admission_error_contract.py

@@ -0,0 +1,18 @@
+"""Static UI contracts for actionable GPU admission failures."""
+
+from pathlib import Path
+
+
+def test_obliterate_catches_admission_before_cuda_cleanup():
+    source = Path("app.py").read_text(encoding="utf-8")
+    obliterate = source.index("def obliterate(")
+    loading = source.index("_gpu_lifecycle.loading(model_id)", obliterate)
+    handler = source.index("except AdmissionError as exc:", loading)
+    cleanup = source.index("_clear_gpu(release_lifecycle=False)", handler)
+
+    assert obliterate < loading < handler < cleanup
+    block = source[loading:cleanup]
+    assert "exc.user_message()" in block
+    assert "exc.diagnostic_message()" in block
+    assert '_state["status"] = "idle"' in block
+    assert "return" in block

tests/test_gpu_lifecycle.py

@@ -127,6 +127,56 @@ def test_admission_failures_never_enter_allocation(tmp_path, decision):
     assert "allocation_started" not in events
 
 
+def test_timeout_error_contains_safe_correlated_diagnostics(tmp_path):
+    publisher = GpuLifecyclePublisher(
+        tmp_path,
+        admission_timeout_seconds=0.02,
+        admission_poll_seconds=0.002,
+        run_id="diagnostic-run",
+    )
+
+    with pytest.raises(AdmissionError) as captured:
+        publisher.loading("org/model")
+
+    error = captured.value
+    assert error.reason == "ack_timeout"
+    assert error.run_id == "diagnostic-run"
+    assert error.request_event_id == "diagnostic-run:1"
+    assert error.elapsed_seconds is not None
+    assert error.timeout_seconds == 0.02
+    assert "No model weights were loaded or modified" in error.user_message()
+    assert "run_id=diagnostic-run" in error.diagnostic_message()
+    assert "lease" not in error.diagnostic_message()
+
+
+def test_supervisor_denial_reason_is_preserved(tmp_path):
+    publisher = GpuLifecyclePublisher(
+        tmp_path,
+        admission_timeout_seconds=0.2,
+        admission_poll_seconds=0.002,
+        run_id="denied-run",
+    )
+
+    def deny():
+        while not (tmp_path / "current.json").exists():
+            time.sleep(0.001)
+        request = json.loads((tmp_path / "current.json").read_text())
+        (tmp_path / "ack.json").write_text(json.dumps({
+            "schema_version": 1,
+            "run_id": "denied-run",
+            "request_event_id": request["event_id"],
+            "decision": "deny",
+            "reason": "broker_admission_failed",
+        }))
+
+    threading.Thread(target=deny).start()
+    with pytest.raises(AdmissionError) as captured:
+        publisher.loading("org/model")
+
+    assert captured.value.reason == "broker_admission_failed"
+    assert "could not reserve" in captured.value.user_message()
+
+
 def test_delayed_ack_blocks_until_granted(tmp_path):
     publisher = GpuLifecyclePublisher(
         tmp_path, admission_timeout_seconds=1, admission_poll_seconds=0.005, run_id="run",