feat(routing): implement Last Known Good Provider (LKGP) strategy (#919)

open-sse/services/autoCombo/routerStrategy.ts

@@ -16,6 +16,7 @@ export interface RoutingContext {
   requestHasTools?: boolean;
   requestHasVision?: boolean;
   estimatedInputTokens?: number;
+  lastKnownGoodProvider?: string;
 }
 
 export interface RoutingDecision {
@@ -116,6 +117,34 @@ class LatencyStrategyImpl implements RouterStrategy {
   }
 }
 
+// ── LKGPStrategy: tries last known good provider first ───────────────────────
+
+class LKGPStrategyImpl implements RouterStrategy {
+  readonly name = "lkgp";
+  readonly description = "Tries last known good provider first, then falls back to rules";
+
+  select(pool: ProviderCandidate[], context: RoutingContext): RoutingDecision {
+    if (context.lastKnownGoodProvider) {
+      const best = pool.find(
+        (c) => c.provider === context.lastKnownGoodProvider && c.circuitBreakerState !== "OPEN"
+      );
+      if (best) {
+        return {
+          provider: best.provider,
+          model: best.model,
+          strategy: this.name,
+          reason: `LKGP: using last known good provider ${best.provider}`,
+          candidatesConsidered: 1,
+          finalScore: 1.0,
+        };
+      }
+    }
+
+    // Fallback to rules strategy
+    return getStrategy("rules").select(pool, context);
+  }
+}
+
 // ── Registry ──────────────────────────────────────────────────────────────────
 
 const strategyRegistry = new Map<string, RouterStrategy>();
@@ -123,12 +152,14 @@ const strategyRegistry = new Map<string, RouterStrategy>();
 const rulesStrategy = new RulesStrategyImpl();
 const costStrategy = new CostStrategyImpl();
 const latencyStrategy = new LatencyStrategyImpl();
+const lkgpStrategy = new LKGPStrategyImpl();
 
 strategyRegistry.set("rules", rulesStrategy);
 strategyRegistry.set("cost", costStrategy);
 strategyRegistry.set("eco", costStrategy); // alias
 strategyRegistry.set("latency", latencyStrategy);
 strategyRegistry.set("fast", latencyStrategy); // alias
+strategyRegistry.set("lkgp", lkgpStrategy);
 
 export function getStrategy(name: string): RouterStrategy {
   const strategy = strategyRegistry.get(name);

open-sse/services/combo.ts

@@ -99,7 +99,10 @@ async function validateResponseQuality(
     if (json?.output || json?.result || json?.data || json?.response) return { valid: true };
     if (json?.error) {
       const err = json.error as Record<string, unknown>;
-      return { valid: false, reason: `upstream error in 200 body: ${err?.message || JSON.stringify(json.error).substring(0, 200)}` };
+      return {
+        valid: false,
+        reason: `upstream error in 200 body: ${err?.message || JSON.stringify(json.error).substring(0, 200)}`,
+      };
     }
     return { valid: true };
   }
@@ -809,6 +812,16 @@ export async function handleComboChat({
     const modePack =
       typeof autoConfigSource.modePack === "string" ? autoConfigSource.modePack : undefined;
 
+    // Retrieve last known good provider (LKGP) for this combo/model (#919)
+    let lastKnownGoodProvider: string | undefined;
+    try {
+      const { getLKGP } = await import("../../src/lib/localDb");
+      const lkgp = await getLKGP(combo.name, combo.id || combo.name);
+      if (lkgp) lastKnownGoodProvider = lkgp;
+    } catch {
+      /* ignore db errors */
+    }
+
     const candidates = await buildAutoCandidates(eligibleModels, combo.name);
     if (candidates.length > 0) {
       let selectedProvider = null;
@@ -819,7 +832,7 @@ export async function handleComboChat({
         try {
           const decision = selectWithStrategy(
             candidates,
-            { taskType, requestHasTools },
+            { taskType, requestHasTools, lastKnownGoodProvider },
             routingStrategy
           );
           selectedProvider = decision.provider;
@@ -980,6 +993,14 @@ export async function handleComboChat({
           fallbackCount,
           strategy,
         });
+
+        // Record last known good provider (LKGP) for this combo/model (#919)
+        if (provider) {
+          import("../../src/lib/localDb")
+            .then(({ setLKGP }) => setLKGP(combo.name, combo.id || combo.name, provider))
+            .catch(() => {});
+        }
+
         return result;
       }
 

src/lib/db/settings.ts

@@ -248,6 +248,31 @@ export async function resetAllPricing() {
   return {};
 }
 
+// ──────────────── LKGP (Last Known Good Provider) ────────────────
+
+export async function getLKGP(comboName: string, modelId: string): Promise<string | null> {
+  const db = getDbInstance();
+  const key = `${comboName}:${modelId}`;
+  const row = db
+    .prepare("SELECT value FROM key_value WHERE namespace = 'lkgp' AND key = ?")
+    .get(key) as { value?: string } | undefined;
+  if (!row?.value) return null;
+  try {
+    return JSON.parse(row.value);
+  } catch {
+    return row.value;
+  }
+}
+
+export async function setLKGP(comboName: string, modelId: string, providerId: string) {
+  const db = getDbInstance();
+  const key = `${comboName}:${modelId}`;
+  db.prepare("INSERT OR REPLACE INTO key_value (namespace, key, value) VALUES ('lkgp', ?, ?)").run(
+    key,
+    JSON.stringify(providerId)
+  );
+}
+
 // ──────────────── Proxy Config ────────────────
 
 const DEFAULT_PROXY_CONFIG: ProxyConfig = { global: null, providers: {}, combos: {}, keys: {} };

src/lib/localDb.ts

@@ -92,6 +92,10 @@ export {
   updateSettings,
   isCloudEnabled,
 
+  // LKGP (Last Known Good Provider) (#919)
+  getLKGP,
+  setLKGP,
+
   // Pricing
   getPricing,
   getPricingForModel,