orchestrator: recover from context overflow on fallback

src/daemon/routing.ts

@@ -79,25 +79,31 @@ export function createMessageRouter(deps: {
     const baseSid = agentConfigName
       ? `${channel}:${senderId}:${agentConfigName}`
       : `${channel}:${senderId}`;
-    const sessionId = tierFromMetadata ? `${baseSid}:${tierFromMetadata}` : baseSid;
+    const session = deps.sessionManager.getSession(channel, senderId);
+
+    // Read per-session model tier override (persisted in SQLite)
+    const sessionTierOverride = session.getConfig('modelTier') as ModelTier | undefined;
+
+    // Resolution chain: metadata (cron) → session override → agent config → global default
+    const effectiveTier = tierFromMetadata
+      ?? sessionTierOverride
+      ?? agentConfig?.modelTier
+      ?? deps.config.agents.primary_tier
+      ?? 'default';
+
+    // Cache agents by tier too so switching tiers updates context-window heuristics.
+    const sessionId = `${baseSid}:${effectiveTier}`;
 
     let entry = agents.get(sessionId);
     if (!entry) {
-      const session = deps.sessionManager.getSession(channel, senderId);
-
-      // Read per-session model tier override (persisted in SQLite)
-      const sessionTierOverride = session.getConfig('modelTier') as ModelTier | undefined;
-
-      // Resolution chain: metadata (cron) → session override → agent config → global default
-      const effectiveTier = tierFromMetadata
-        ?? sessionTierOverride
-        ?? agentConfig?.modelTier
-        ?? deps.config.agents.primary_tier
-        ?? 'default';
-
       // Use agent config overrides where available, falling back to global config
       const effectiveSystemPrompt = agentConfig?.systemPrompt ?? deps.systemPrompt;
-      const effectiveProvider = deps.config.models.default.provider;
+
+      const modelsConfig = deps.config.models as Record<string, { provider?: string; model?: string; context_window?: number } | undefined>;
+      const tierConfig = modelsConfig[effectiveTier] ?? deps.config.models.default;
+      const effectiveProvider = tierConfig?.provider ?? deps.config.models.default.provider;
+      const effectiveModelName = tierConfig?.model ?? deps.config.models.default.model;
+      const effectiveContextWindow = tierConfig?.context_window ?? deps.config.models.default.context_window;
 
       const delegationConfig: DelegationConfig = {
         compaction: deps.config.agents.delegation.compaction ?? 'fast',
@@ -181,8 +187,8 @@ export function createMessageRouter(deps: {
           summaryMaxTokens: deps.config.compaction.summary_max_tokens,
           importanceThreshold: deps.config.compaction.importance_threshold,
         } : undefined,
-        modelName: deps.config.models.default.model,
-        contextWindow: deps.config.models.default.context_window,
+        modelName: effectiveModelName,
+        contextWindow: effectiveContextWindow,
         memoryStore: deps.memoryStore,
         memoryInjectionStrategy: deps.config.memory?.injection_strategy,
         memoryMaxInjectionTokens: deps.config.memory?.max_injection_tokens,