[kimi] Add /api/matrix/health endpoint (#685) (#745)

src/dashboard/routes/world.py

@@ -770,6 +770,120 @@ async def get_matrix_thoughts(limit: int = _DEFAULT_THOUGHT_LIMIT) -> JSONRespon
     )
 
 
+# ---------------------------------------------------------------------------
+# Matrix Health Endpoint — backend capability discovery
+# ---------------------------------------------------------------------------
+
+# Health check cache (5-second TTL for capability checks)
+_health_cache: dict | None = None
+_health_cache_ts: float = 0.0
+_HEALTH_CACHE_TTL = 5.0
+
+
+def _check_capability_thinking() -> bool:
+    """Check if thinking engine is available."""
+    try:
+        from timmy.thinking import thinking_engine
+
+        # Check if the engine has been initialized (has a db path)
+        return hasattr(thinking_engine, "_db") and thinking_engine._db is not None
+    except Exception:
+        return False
+
+
+def _check_capability_memory() -> bool:
+    """Check if memory system is available."""
+    try:
+        from timmy.memory_system import HOT_MEMORY_PATH
+
+        return HOT_MEMORY_PATH.exists()
+    except Exception:
+        return False
+
+
+def _check_capability_bark() -> bool:
+    """Check if bark production is available."""
+    try:
+        from infrastructure.presence import produce_bark
+
+        return callable(produce_bark)
+    except Exception:
+        return False
+
+
+def _check_capability_familiar() -> bool:
+    """Check if familiar (Pip) is available."""
+    try:
+        from timmy.familiar import pip_familiar
+
+        return pip_familiar is not None
+    except Exception:
+        return False
+
+
+def _check_capability_lightning() -> bool:
+    """Check if Lightning payments are available."""
+    # Lightning is currently disabled per health.py
+    # Returns False until properly re-implemented
+    return False
+
+
+def _build_matrix_health_response() -> dict[str, Any]:
+    """Build the Matrix health response with capability checks.
+
+    Performs lightweight checks (<100ms total) to determine which features
+    are available. Returns 200 even if some capabilities are degraded.
+    """
+    capabilities = {
+        "thinking": _check_capability_thinking(),
+        "memory": _check_capability_memory(),
+        "bark": _check_capability_bark(),
+        "familiar": _check_capability_familiar(),
+        "lightning": _check_capability_lightning(),
+    }
+
+    # Status is ok if core capabilities (thinking, memory, bark) are available
+    core_caps = ["thinking", "memory", "bark"]
+    core_available = all(capabilities[c] for c in core_caps)
+    status = "ok" if core_available else "degraded"
+
+    return {
+        "status": status,
+        "version": "1.0.0",
+        "capabilities": capabilities,
+    }
+
+
+@matrix_router.get("/health")
+async def get_matrix_health() -> JSONResponse:
+    """Return health status and capability availability for Matrix frontend.
+
+        This endpoint allows the Matrix frontend to discover what backend
+    capabilities are available so it can show/hide UI elements:
+        - thinking: Show thought bubbles if enabled
+        - memory: Show crystal ball memory search if available
+        - bark: Enable visitor chat responses
+        - familiar: Show Pip the familiar
+        - lightning: Enable payment features
+
+        Response time is <100ms (no heavy checks). Returns 200 even if
+        some capabilities are degraded.
+
+        Response:
+            - status: "ok" or "degraded"
+            - version: API version string
+            - capabilities: dict of feature:bool
+    """
+    response = _build_matrix_health_response()
+    status_code = 200  # Always 200, even if degraded
+
+    return JSONResponse(
+        content=response,
+        status_code=status_code,
+        headers={"Cache-Control": "no-cache, no-store"},
+    )
+
+
 # ---------------------------------------------------------------------------
 # Matrix Memory Search Endpoint — visitors query Timmy's memory
 # ---------------------------------------------------------------------------