From 7a697944184eae11d9c2a46a5338c535b8ec6a53 Mon Sep 17 00:00:00 2001
From: William Valentin <william.valentin.info@gmail.com>
Date: Tue, 10 Feb 2026 20:22:40 -0800
Subject: [PATCH] fix: sync model tier between TUI and WebChat when switching
 models

ModelRouter now supports multiple tier-change listeners via addOnTierChange(),
SessionBridge subscribes to tier changes and propagates them to all WebChat
agents (both existing and newly created), and the fullscreen TUI now also
updates the agent's tier when switching models (matching minimal TUI behavior).
---
 src/frontends/tui/components/App.tsx |  4 ++++
 src/gateway/session-bridge.ts        | 22 +++++++++++++++++++++-
 src/models/router.ts                 | 17 +++++++++++++----
 3 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/src/frontends/tui/components/App.tsx b/src/frontends/tui/components/App.tsx
index d4dc49f..9f0e0a9 100644
--- a/src/frontends/tui/components/App.tsx
+++ b/src/frontends/tui/components/App.tsx
@@ -191,6 +191,10 @@ export function App({
         }
         const tier = resolveModelAlias(command.name);
         if (modelRouter.setTier(tier)) {
+          // Also update the agent tier so chatWithRouter uses the correct client
+          if (agent) {
+            agent.setModelTier(tier);
+          }
           setCurrentModel(tier);
           const successMsg: Message = { role: 'assistant', content: `Switched to model: ${tier}` };
           const successWithTs = session.addMessage(successMsg);
diff --git a/src/gateway/session-bridge.ts b/src/gateway/session-bridge.ts
index f61ffec..9e7c021 100644
--- a/src/gateway/session-bridge.ts
+++ b/src/gateway/session-bridge.ts
@@ -2,7 +2,7 @@ import { randomUUID } from 'crypto';
 import type { SessionManager } from '../session/manager.js';
 import type { Session } from '../session/manager.js';
 import type { ModelClient } from '../models/types.js';
-import type { ModelRouter } from '../models/router.js';
+import type { ModelRouter, ModelTier } from '../models/router.js';
 import type { ToolRegistry } from '../tools/registry.js';
 import type { ToolExecutor } from '../tools/executor.js';
 import { NativeAgent } from '../backends/native/agent.js';
@@ -27,9 +27,27 @@ export class SessionBridge {
   private clients: Map<string, ClientEntry> = new Map();
   private agents: Map<string, NativeAgent> = new Map();
   private config: SessionBridgeConfig;
+  /** Tracks the current model tier so new agents inherit it and existing agents stay in sync. */
+  private currentTier: ModelTier = 'default';
 
   constructor(config: SessionBridgeConfig) {
     this.config = config;
+
+    // If the model client is a ModelRouter, subscribe to tier changes
+    // so all WebChat agents stay in sync with TUI model switches.
+    if ('getClient' in config.modelClient) {
+      const router = config.modelClient as ModelRouter;
+      this.currentTier = router.getTier();
+      router.addOnTierChange((tier: ModelTier) => this.onTierChanged(tier));
+    }
+  }
+
+  /** Called when the ModelRouter's active tier changes. Updates all existing agents. */
+  private onTierChanged(tier: ModelTier): void {
+    this.currentTier = tier;
+    for (const agent of this.agents.values()) {
+      agent.setModelTier(tier);
+    }
   }
 
   /** Register a new WS connection. Returns the assigned connection ID. */
@@ -172,6 +190,8 @@ export class SessionBridge {
         toolRegistry: this.config.toolRegistry,
         toolExecutor: this.config.toolExecutor,
       });
+      // Inherit the current model tier so the agent uses the same model as the TUI
+      agent.setModelTier(this.currentTier);
       this.agents.set(sessionId, agent);
     }
     return agent;
diff --git a/src/models/router.ts b/src/models/router.ts
index 9be6c0d..392c93b 100644
--- a/src/models/router.ts
+++ b/src/models/router.ts
@@ -26,7 +26,7 @@ export class ModelRouter implements ModelClient {
   private currentTier: ModelTier = 'default';
   private localProviderName?: string;
   private retryConfig?: RetryConfig;
-  private onTierChange?: (tier: ModelTier) => void;
+  private tierChangeListeners: Array<(tier: ModelTier) => void> = [];
 
   constructor(config: ModelRouterConfig) {
     this.clients = new Map();
@@ -35,7 +35,10 @@ export class ModelRouter implements ModelClient {
     this.fallbackChain = config.fallbackChain;
     this.tierFallbacks = config.tierFallbacks ?? new Map();
     this.retryConfig = config.retryConfig;
-    this.onTierChange = config.onTierChange;
+
+    if (config.onTierChange) {
+      this.tierChangeListeners.push(config.onTierChange);
+    }
 
     this.clients.set('default', config.default);
     if (config.fast) this.clients.set('fast', config.fast);
@@ -54,14 +57,20 @@ export class ModelRouter implements ModelClient {
   setTier(tier: ModelTier): boolean {
     if (this.clients.has(tier)) {
       this.currentTier = tier;
-      this.onTierChange?.(tier);
+      for (const listener of this.tierChangeListeners) {
+        listener(tier);
+      }
       return true;
     }
     return false;
   }
 
   setOnTierChange(callback: (tier: ModelTier) => void): void {
-    this.onTierChange = callback;
+    this.tierChangeListeners = [callback];
+  }
+
+  addOnTierChange(callback: (tier: ModelTier) => void): void {
+    this.tierChangeListeners.push(callback);
   }
 
   getTier(): ModelTier {