feat(2.0): Phase 1 — Engine + Routing (Herzstueck)

Backend-Services: fit/caps/sources (portiert), discover (live HF + Fit +
Caps + ranked recommendation), llama-swap write/register + groups (Ko-
Residenz swap:false), LiteLLM-Gateway-Config + gateway-Service (model:auto +
Fallbacks). Router: discover/fit/register/groups/routing; health zeigt
gateway_reachable. Frontend: Modelle&Routing mit Caps-Chips, Fit-Badges,
Discover-Tab (live), Routing-View.

Lokal verifiziert: Backend-Smoke (alle Endpunkte) + Frontend-Build +
Browser (Shell, Discover, Caps/Fit). Box-Verifikation offen.

Docs: README + docs/STATUS.md (Phasen-Tracker + Resume-Guide).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/services/gateway.py

@@ -0,0 +1,69 @@
+"""
+Routing-Gateway-Service: liest/schreibt die LiteLLM-Config und prüft die
+Erreichbarkeit. MC verwaltet damit die Modell-Zuordnung (welcher llama-swap-Alias
+ist fast/heavy/vision/coder) und die Routing-Regeln.
+"""
+
+import httpx
+
+from config import GATEWAY_CONFIG_PATH, GATEWAY_URL, yaml
+
+
+def read_gateway_config() -> dict:
+    if not GATEWAY_CONFIG_PATH.exists():
+        return {"model_list": [], "litellm_settings": {}, "router_settings": {}}
+    with GATEWAY_CONFIG_PATH.open("r", encoding="utf-8") as f:
+        return yaml.load(f) or {}
+
+
+def write_gateway_config(cfg: dict) -> None:
+    import os
+    GATEWAY_CONFIG_PATH.parent.mkdir(parents=True, exist_ok=True)
+    tmp = GATEWAY_CONFIG_PATH.with_name(GATEWAY_CONFIG_PATH.name + ".tmp")
+    with tmp.open("w", encoding="utf-8") as f:
+        yaml.dump(cfg, f)
+    os.replace(tmp, GATEWAY_CONFIG_PATH)
+
+
+def routing_summary() -> dict:
+    """Kompakte Sicht für die UI: welcher Backend-Alias steckt hinter welchem
+    Gateway-Modellnamen + die Fallback-Ketten."""
+    cfg = read_gateway_config()
+    routes = []
+    for entry in cfg.get("model_list") or []:
+        params = entry.get("litellm_params") or {}
+        routes.append({
+            "name": entry.get("model_name"),
+            "target": str(params.get("model", "")),
+            "api_base": params.get("api_base"),
+        })
+    settings = cfg.get("litellm_settings") or {}
+    return {
+        "routes": routes,
+        "fallbacks": settings.get("fallbacks") or [],
+        "context_window_fallbacks": settings.get("context_window_fallbacks") or [],
+    }
+
+
+def set_route(name: str, target_alias: str, api_base: str = "http://127.0.0.1:8080/v1") -> None:
+    """Einen Gateway-Modellnamen (z.B. 'fast') auf einen llama-swap-Alias mappen."""
+    cfg = read_gateway_config()
+    ml = cfg.setdefault("model_list", [])
+    params = {"model": f"openai/{target_alias}", "api_base": api_base, "api_key": "sk-noauth"}
+    for entry in ml:
+        if entry.get("model_name") == name:
+            entry["litellm_params"] = params
+            break
+    else:
+        ml.append({"model_name": name, "litellm_params": params})
+    write_gateway_config(cfg)
+
+
+def gateway_reachable() -> bool:
+    try:
+        with httpx.Client(timeout=3.0) as c:
+            # LiteLLM hat /health/liveliness; /v1/models tut's auch.
+            r = c.get(f"{GATEWAY_URL}/v1/models")
+            return r.status_code in (200, 401)
+    except Exception:
+        return False