feat: add runtime provider/model switching via /model <tier> <provider/model>

- ModelRouter: add setClient(), labels map, getLabel(), getAllLabels()
- TUI commands: parse /model <tier> <provider/model> syntax with autocompletion
- TUI minimal: handle provider switching via createClientFromConfig factory
- Daemon: wire initial labels into router config
- Fix /model alias mappings (opus=complex, sonnet=default, haiku=fast)
- Add design doc and update state.json with feature status

docs/plans/2026-02-06-provider-model-switching-design.md

@@ -0,0 +1,79 @@
+# Provider/Model Runtime Switching
+
+**Date:** 2026-02-06
+**Status:** In Progress
+
+## Goal
+
+Enable easy runtime switching of model providers per tier via the `/model` command, using `provider/model` syntax.
+
+## Commands
+
+```
+/model                                    — Show all tiers with provider/model labels
+/model fast                               — Switch active tier (existing behavior)
+/model default github-copilot/claude-sonnet-4-5  — Change default tier's provider+model
+/model complex anthropic/claude-opus-4    — Change complex tier's provider+model
+/model fast github-copilot/gpt-4o-mini    — Change fast tier's provider+model
+```
+
+## Design Decisions
+
+1. **No presets** — Direct `provider/model` targeting per tier. YAGNI.
+2. **Full override** — When you set a tier, it fully replaces the previous client.
+3. **Local tier excluded** — `/model local` continues to use `/backend` for switching. Local models are a different concern.
+4. **Auth** — Config-based `api_key` for most providers. `/login` OAuth flow for GitHub Copilot (already implemented).
+5. **Merged into /model** — No separate `/provider` command. Everything lives under `/model`.
+
+## Implementation
+
+### 1. ModelRouter (`src/models/router.ts`)
+
+- Add `setClient(tier: ModelTier, client: ModelClient, label: string)` — replaces a tier's client at runtime
+- Add `getLabel(tier: ModelTier): string` — returns `provider/model` string for display
+- Track labels in a `Map<ModelTier, string>` populated at construction and updated by `setClient()`
+
+### 2. Client Factory (`src/daemon/index.ts`)
+
+Extract `createClientFromProvider(provider: string, model: string, opts?: { apiKey?: string; endpoint?: string }): ModelClient` factory function from the existing inline client creation logic. Used by both daemon startup and runtime `/model` switching.
+
+### 3. Command Parser (`src/frontends/tui/commands.ts`)
+
+- Extend `Command` type: `{ type: 'model'; name?: string; providerModel?: string }`
+- Parse `/model <tier> <provider/model>` — split on space to get tier + provider/model
+- Parse provider/model string: split on first `/` to get provider and model name
+- Update autocompletion to suggest available providers after tier name
+- Update tooltips
+
+### 4. Daemon Wiring (`src/daemon/index.ts`)
+
+Handle the new command variant:
+1. Receive `{ type: 'model', name: 'default', providerModel: 'github-copilot/claude-sonnet-4-5' }`
+2. Parse provider and model from `providerModel`
+3. Call `createClientFromProvider(provider, model)` to instantiate client
+4. Call `router.setClient('default', client, 'github-copilot/claude-sonnet-4-5')`
+5. Respond with confirmation message
+
+### 5. Provider Name Mapping
+
+Map short provider names to client constructors:
+
+| Provider Name | Client Class |
+|---------------|-------------|
+| `anthropic` | AnthropicClient |
+| `openai` | OpenAIClient |
+| `github` / `github-copilot` | GitHubModelsClient |
+| `gemini` | GeminiClient |
+| `bedrock` | BedrockClient |
+| `ollama` | OllamaClient |
+| `llamacpp` | LlamaCppClient |
+
+## Files Changed
+
+| File | Change |
+|------|--------|
+| `src/models/router.ts` | Add `setClient()`, `getLabel()`, label tracking |
+| `src/models/router.test.ts` | Tests for new methods |
+| `src/frontends/tui/commands.ts` | Extended parser, completions, tooltips |
+| `src/frontends/tui/commands.test.ts` | Tests for new parsing |
+| `src/daemon/index.ts` | Extract factory, wire new command handler |

docs/plans/state.json

@@ -336,6 +336,136 @@
         }
       }
     },
+    "p4-media-pipeline": {
+      "status": "completed",
+      "date": "2026-02-06",
+      "summary": "Multimodal media pipeline: receive images from channel adapters and pass through to vision-capable models (Anthropic, OpenAI, Gemini, Bedrock)",
+      "phases": {
+        "type_widening": {
+          "priority": "P4",
+          "status": "completed",
+          "description": "Widen Message.content from string to string | MessageContentPart[], add Attachment type to channel layer, add ImageSource/MessageContentPart types",
+          "files_created": [
+            "src/models/media.ts",
+            "src/models/media.test.ts"
+          ],
+          "files_modified": [
+            "src/models/types.ts",
+            "src/models/index.ts",
+            "src/channels/types.ts",
+            "src/channels/index.ts"
+          ],
+          "test_status": "25/25 passing"
+        },
+        "model_client_multimodal": {
+          "priority": "P4",
+          "status": "completed",
+          "description": "Update all model clients to convert MessageContentPart[] to provider-specific image formats (Anthropic base64, OpenAI data URI, Gemini inlineData, Bedrock image bytes)",
+          "files_modified": [
+            "src/models/anthropic.ts",
+            "src/models/openai.ts",
+            "src/models/gemini.ts",
+            "src/models/bedrock.ts",
+            "src/models/local/llamacpp.ts",
+            "src/models/local/ollama.ts"
+          ]
+        },
+        "agent_attachment_passthrough": {
+          "priority": "P4",
+          "status": "completed",
+          "description": "Wire attachments through NativeAgent.process() and AgentOrchestrator.process() to daemon message handler",
+          "files_modified": [
+            "src/backends/native/agent.ts",
+            "src/backends/native/orchestrator.ts",
+            "src/daemon/index.ts"
+          ]
+        },
+        "downstream_type_fixes": {
+          "priority": "P4",
+          "status": "completed",
+          "description": "Fix all consumers of Message.content to use getMessageText() helper: token estimation, compaction, TUI rendering",
+          "files_modified": [
+            "src/context/tokens.ts",
+            "src/context/compaction.ts",
+            "src/frontends/tui/components/MessageList.tsx"
+          ]
+        },
+        "channel_adapter_extraction": {
+          "priority": "P4",
+          "status": "completed",
+          "description": "Extract images from platform messages in all channel adapters",
+          "sub_phases": {
+            "telegram": {
+              "status": "completed",
+              "description": "Handle message:photo (largest size, download via getFile API, base64) and image message:document events with caption text",
+              "files_modified": ["src/channels/telegram/adapter.ts"]
+            },
+            "discord": {
+              "status": "completed",
+              "description": "Extract image attachments from message.attachments Collection, pass Discord CDN URLs directly",
+              "files_modified": ["src/channels/discord/adapter.ts"]
+            },
+            "slack": {
+              "status": "completed",
+              "description": "Download image files via url_private_download with bot token auth, base64 encode",
+              "files_modified": ["src/channels/slack/adapter.ts"]
+            },
+            "whatsapp": {
+              "status": "completed",
+              "description": "Use downloadMedia() from whatsapp-web.js (returns base64 natively)",
+              "files_modified": ["src/channels/whatsapp/adapter.ts"]
+            },
+            "webchat": {
+              "status": "deferred",
+              "description": "Requires gateway protocol update for WebSocket attachment messages"
+            }
+          }
+        }
+      }
+    },
+    "p5-github-copilot-provider": {
+      "status": "completed",
+      "date": "2026-02-06",
+      "summary": "GitHub Copilot as a model provider with OAuth device flow and auto-login on first use",
+      "phases": {
+        "copilot_client": {
+          "priority": "P5",
+          "status": "completed",
+          "description": "GitHubModelsClient using OpenAI SDK against api.githubcopilot.com with Copilot-specific headers, multimodal support, streaming, tool calls",
+          "files_created": [
+            "src/models/github.ts",
+            "src/auth/github.ts",
+            "src/auth/index.ts"
+          ],
+          "files_modified": [
+            "src/config/schema.ts",
+            "src/models/index.ts",
+            "src/models/costs.ts",
+            "src/daemon/index.ts",
+            "src/cli/tui.ts"
+          ]
+        },
+        "oauth_device_flow": {
+          "priority": "P5",
+          "status": "completed",
+          "description": "Interactive OAuth device flow via /login github command, token stored at ~/.config/flynn/auth.json with chmod 0600",
+          "files_modified": [
+            "src/frontends/tui/minimal.ts",
+            "src/frontends/tui/commands.ts"
+          ]
+        },
+        "auto_login": {
+          "priority": "P5",
+          "status": "completed",
+          "description": "Lazy token resolution with onLoginRequired callback — triggers OAuth device flow automatically on first API call when no token is available",
+          "files_modified": [
+            "src/models/github.ts",
+            "src/daemon/index.ts",
+            "src/cli/tui.ts"
+          ]
+        }
+      }
+    },
     "earlier_plans": {
       "status": "completed",
       "summary": "Original design and implementation phases from 2026-02-02 to 2026-02-05",
@@ -361,11 +491,14 @@
   },
 
   "overall_progress": {
-    "total_test_count": 655,
+    "total_test_count": 742,
     "all_tests_passing": true,
     "p0_completion": "3/3 (100%)",
     "p1_completion": "4/4 (100%)",
     "p2_completion": "7/7 (100%)",
-    "next_up": "p3_remaining (group chat support, gateway auth, gemini provider, browser control, additional model providers)"
+    "p3_completion": "completed (group chat, gateway auth, Gemini, OpenRouter, Bedrock, browser control)",
+    "p4_completion": "1/1 (100%) — multimodal media pipeline",
+    "p5_completion": "1/1 (100%) — GitHub Copilot provider with auto-login",
+    "next_up": "p6 (image.analyze tool, audio transcription, outbound attachments, gateway protocol attachments)"
   }
 }

src/daemon/index.ts

@@ -179,6 +179,12 @@ function createModelRouter(config: Config): ModelRouter {
     local: localClient,
     fallbackChain,
     retryConfig,
+    labels: {
+      default: `${models.default.provider}/${models.default.model}`,
+      ...(models.fast ? { fast: `${models.fast.provider}/${models.fast.model}` } : {}),
+      ...(models.complex ? { complex: `${models.complex.provider}/${models.complex.model}` } : {}),
+      ...(models.local ? { local: `${models.local.provider}/${models.local.model}` } : {}),
+    },
   });
 }
 

src/frontends/tui/commands.test.ts

@@ -43,6 +43,32 @@ describe('parseCommand', () => {
     expect(parseCommand('/model opus')).toEqual({ type: 'model', name: 'opus' });
   });
 
+  it('parses /model with provider/model', () => {
+    expect(parseCommand('/model default anthropic/claude-sonnet-4')).toEqual({
+      type: 'model',
+      name: 'default',
+      providerModel: 'anthropic/claude-sonnet-4',
+    });
+    expect(parseCommand('/model fast github-copilot/gpt-4o-mini')).toEqual({
+      type: 'model',
+      name: 'fast',
+      providerModel: 'github-copilot/gpt-4o-mini',
+    });
+    expect(parseCommand('/model complex openai/o3')).toEqual({
+      type: 'model',
+      name: 'complex',
+      providerModel: 'openai/o3',
+    });
+  });
+
+  it('still parses /model fast as tier switch (no providerModel)', () => {
+    expect(parseCommand('/model fast')).toEqual({ type: 'model', name: 'fast' });
+  });
+
+  it('still parses /model as info (no args)', () => {
+    expect(parseCommand('/model')).toEqual({ type: 'model' });
+  });
+
   it('parses /backend command without argument', () => {
     expect(parseCommand('/backend')).toEqual({ type: 'backend' });
   });

src/frontends/tui/commands.ts

@@ -6,7 +6,7 @@ export type Command =
   | { type: 'fullscreen' }
   | { type: 'compact' }
   | { type: 'usage' }
-  | { type: 'model'; name?: string }
+  | { type: 'model'; name?: string; providerModel?: string }
   | { type: 'backend'; provider?: string }
   | { type: 'login'; provider?: string }
   | { type: 'transfer'; target: string }
@@ -56,7 +56,16 @@ export function parseCommand(input: string): Command | null {
     return { type: 'model' };
   }
   if (trimmed.startsWith('/model ')) {
-    const name = trimmed.slice('/model '.length).trim();
+    const args = trimmed.slice('/model '.length).trim();
+    const parts = args.split(/\s+/);
+    
+    // /model <tier> <provider/model> - change tier's provider/model
+    if (parts.length === 2 && parts[1].includes('/')) {
+      return { type: 'model', name: parts[0], providerModel: parts[1] };
+    }
+    
+    // /model <name> - single word (backward compatibility)
+    const name = parts[0];
     return { type: 'model', name };
   }
 
@@ -92,7 +101,8 @@ export function getHelpText(): string {
   return `
 Commands:
   /help, /?              Show this help
-  /model [name]          Show or switch model (local, default, fast, complex)
+  /model [name]          Show or switch model tier (local, default, fast, complex)
+  /model <tier> <p/m>    Change tier's provider/model (e.g. /model default anthropic/claude-sonnet-4)
   /backend [provider]    Show or switch local backend (ollama, llamacpp)
   /login [provider]      Authenticate with GitHub
   /reset, /clear, /new   Clear conversation history
@@ -105,7 +115,7 @@ Commands:
 `.trim();
 }
 
-export type ModelAlias = 'local' | 'default' | 'fast' | 'complex' | 'opus' | 'sonnet' | 'ollama';
+export type ModelAlias = 'local' | 'default' | 'fast' | 'complex' | 'opus' | 'sonnet' | 'haiku' | 'ollama';
 
 // List of all slash commands for autocompletion
 export const SLASH_COMMANDS = [
@@ -146,28 +156,44 @@ export const COMMAND_TOOLTIPS: Record<string, string> = {
 };
 
 // Model aliases for /model command autocompletion
-export const MODEL_ALIASES = ['local', 'default', 'fast', 'complex', 'opus', 'sonnet', 'ollama'];
+export const MODEL_ALIASES = ['local', 'default', 'fast', 'complex', 'opus', 'sonnet', 'haiku', 'ollama'];
+
+// Provider names for /model <tier> <provider/model> syntax
+export const PROVIDER_NAMES = ['anthropic', 'openai', 'github-copilot', 'gemini', 'bedrock', 'ollama', 'llamacpp'];
 
 // Model alias descriptions
 export const MODEL_TOOLTIPS: Record<string, string> = {
-  local: 'Local Ollama model',
-  default: 'Default model (Opus)',
-  fast: 'Fast model (Sonnet)',
-  complex: 'Complex reasoning model',
-  opus: 'Claude Opus',
-  sonnet: 'Claude Sonnet',
-  ollama: 'Local Ollama model',
+  local: 'Local model (Ollama/llama.cpp)',
+  default: 'Default model tier',
+  fast: 'Fast/lightweight model tier',
+  complex: 'Complex reasoning model tier',
+  opus: 'Alias for complex tier',
+  sonnet: 'Alias for default tier',
+  haiku: 'Alias for fast tier',
+  ollama: 'Alias for local tier',
 };
 
 export function getCommandCompletions(partial: string): string[] {
   const trimmed = partial.trim();
   
-  // Complete /model arguments
+  // Complete /model <tier> <provider/model>
   if (trimmed.startsWith('/model ')) {
-    const modelPartial = trimmed.slice('/model '.length).toLowerCase();
+    const args = trimmed.slice('/model '.length).trim();
+    const parts = args.split(/\s+/);
+    
+    if (parts.length === 1) {
+      // Single word - suggest model aliases
+      const modelPartial = parts[0].toLowerCase();
       return MODEL_ALIASES
         .filter(alias => alias.startsWith(modelPartial))
         .map(alias => `/model ${alias}`);
+    } else if (parts.length === 2) {
+      // Two words - suggest provider prefixes
+      const providerPartial = parts[1].toLowerCase();
+      return PROVIDER_NAMES
+        .filter(provider => provider.startsWith(providerPartial))
+        .map(provider => `/model ${parts[0]} ${provider}`);
+    }
   }
   
   // Complete slash commands
@@ -183,7 +209,12 @@ export function getCommandTooltip(partial: string): string | null {
   
   // Tooltip for /model arguments
   if (trimmed.startsWith('/model ')) {
-    const modelArg = trimmed.slice('/model '.length).trim();
+    const args = trimmed.slice('/model '.length).trim();
+    const parts = args.split(/\s+/);
+    
+    if (parts.length === 1) {
+      // Single word - model tier or provider
+      const modelArg = parts[0].toLowerCase();
       if (modelArg && MODEL_TOOLTIPS[modelArg]) {
         return MODEL_TOOLTIPS[modelArg];
       }
@@ -193,6 +224,15 @@ export function getCommandTooltip(partial: string): string | null {
         return MODEL_TOOLTIPS[matches[0]];
       }
       return 'Choose: local, default, fast, complex';
+    } else if (parts.length === 2) {
+      // Two words - tier + provider
+      const providerPartial = parts[1].toLowerCase();
+      const matches = PROVIDER_NAMES.filter(p => p.startsWith(providerPartial));
+      if (matches.length === 1) {
+        return `Enter provider/model (e.g. ${matches[0]}/...)`;
+      }
+      return `Enter provider/model (e.g. anthropic/claude-sonnet-4)`;
+    }
   }
   
   // Exact match tooltip
@@ -216,10 +256,11 @@ export function resolveModelAlias(alias: string): 'local' | 'default' | 'fast' |
     local: 'local',
     ollama: 'local',
     default: 'default',
-    opus: 'default',
+    sonnet: 'default',
     fast: 'fast',
-    sonnet: 'fast',
+    haiku: 'fast',
     complex: 'complex',
+    opus: 'complex',
   };
   return map[alias.toLowerCase()] ?? 'default';
 }

src/frontends/tui/minimal.ts

@@ -7,6 +7,7 @@ import { parseCommand, getHelpText, resolveModelAlias, getCommandCompletions, ge
 import { renderMarkdown } from './markdown.js';
 import type { ModelConfig } from '../../config/schema.js';
 import { OllamaClient, LlamaCppClient } from '../../models/index.js';
+import { createClientFromConfig } from '../../daemon/index.js';
 import { loginGitHub } from '../../auth/index.js';
 
 export { parseCommand, type Command };
@@ -180,7 +181,7 @@ export class MinimalTui {
         break;
 
       case 'model':
-        this.handleModelCommand(command.name);
+        this.handleModelCommand(command.name, command.providerModel);
         break;
 
       case 'backend':
@@ -201,21 +202,51 @@ export class MinimalTui {
     }
   }
 
-  private handleModelCommand(name?: string): void {
+  private handleModelCommand(name?: string, providerModel?: string): void {
     const router = this.config.modelRouter;
     if (!router) {
       console.log(`${colors.gray}Model switching not available.${colors.reset}\n`);
       return;
     }
 
-    if (!name) {
-      const current = router.getTier();
-      const available = router.getAvailableTiers();
-      console.log(`${colors.gray}Current model:${colors.reset} ${current}`);
-      console.log(`${colors.gray}Available:${colors.reset} ${available.join(', ')}\n`);
+    // /model <tier> <provider/model> — change a tier's provider and model
+    if (name && providerModel) {
+      const tier = resolveModelAlias(name);
+      const slashIdx = providerModel.indexOf('/');
+      if (slashIdx === -1) {
+        console.log(`${colors.gray}Invalid format. Use provider/model (e.g. anthropic/claude-sonnet-4)${colors.reset}\n`);
+        return;
+      }
+      const provider = providerModel.slice(0, slashIdx);
+      const model = providerModel.slice(slashIdx + 1);
+
+      try {
+        const client = createClientFromConfig({ provider: provider as 'anthropic', model });
+        router.setClient(tier, client, providerModel);
+        console.log(`${colors.gray}Set ${tier} to:${colors.reset} ${providerModel}\n`);
+      } catch (error) {
+        const message = error instanceof Error ? error.message : String(error);
+        console.log(`${colors.gray}Failed to create client:${colors.reset} ${message}\n`);
+      }
       return;
     }
 
+    // /model — show all tiers with labels
+    if (!name) {
+      const current = router.getTier();
+      const available = router.getAvailableTiers();
+      const labels = router.getAllLabels();
+      console.log(`${colors.gray}Active tier:${colors.reset} ${current}`);
+      for (const tier of available) {
+        const label = labels[tier] ?? 'unknown';
+        const marker = tier === current ? ' ←' : '';
+        console.log(`  ${tier}: ${label}${marker}`);
+      }
+      console.log();
+      return;
+    }
+
+    // /model <tier> — switch active tier
     const tier = resolveModelAlias(name);
     if (router.setTier(tier)) {
       // Also update the agent tier so chatWithRouter uses the correct client

src/models/router.test.ts

@@ -169,3 +169,149 @@ describe('ModelRouter local client switching', () => {
     expect(router.getClient('local')).toBe(mockLocal2);
   });
 });
+
+describe('setClient and labels', () => {
+  it('setClient replaces an existing tier client', async () => {
+    const mockClient1 = { chat: vi.fn() } as unknown as ModelClient;
+    const mockClient2 = { chat: vi.fn() } as unknown as ModelClient;
+
+    const router = new ModelRouter({
+      default: { chat: vi.fn() } as unknown as ModelClient,
+      fast: mockClient1,
+      fallbackChain: [],
+    });
+
+    await router.chat({ messages: [{ role: 'user', content: 'Test' }] }, 'fast');
+
+    expect(mockClient1.chat).toHaveBeenCalled();
+    expect(mockClient1.chat).toHaveBeenCalledTimes(1);
+
+    router.setClient('fast', mockClient2, 'fast-replaced');
+
+    const newFastClient = router.getClient('fast');
+    expect(newFastClient).toBeDefined();
+    await router.chat({ messages: [{ role: 'user', content: 'Test' }] }, 'fast');
+
+    expect(newFastClient!.chat).toHaveBeenCalled();
+    expect(newFastClient!.chat).toHaveBeenCalledTimes(1);
+    expect(mockClient1.chat).toHaveBeenCalledTimes(1);
+  });
+
+  it('setClient adds a new tier client', async () => {
+    const mockClient1 = { chat: vi.fn() } as unknown as ModelClient;
+    const mockClient2 = { chat: vi.fn() } as unknown as ModelClient;
+
+    const router = new ModelRouter({
+      default: mockClient1,
+      fallbackChain: [],
+    });
+
+    expect(router.getClient('complex')).toBeUndefined();
+
+    router.setClient('complex', mockClient2, 'complex-tier');
+
+    const newClient = router.getClient('complex');
+    expect(newClient).toBe(mockClient2);
+
+    await router.chat({ messages: [{ role: 'user', content: 'Test' }] }, 'complex');
+
+    expect(newClient!.chat).toHaveBeenCalled();
+  });
+
+  it('getLabel returns the label set by setClient', () => {
+    const router = new ModelRouter({
+      default: { chat: vi.fn() } as unknown as ModelClient,
+      fallbackChain: [],
+    });
+
+    expect(router.getLabel('fast')).toBe('unknown');
+
+    router.setClient('fast', { chat: vi.fn() } as unknown as ModelClient, 'fast-tier');
+
+    expect(router.getLabel('fast')).toBe('fast-tier');
+  });
+
+  it('getLabel returns "unknown" for unset tier', () => {
+    const router = new ModelRouter({
+      default: { chat: vi.fn() } as unknown as ModelClient,
+      fallbackChain: [],
+    });
+
+    expect(router.getLabel('fast')).toBe('unknown');
+    expect(router.getLabel('complex')).toBe('unknown');
+  });
+
+  it('getAllLabels returns all tier labels', () => {
+    const router = new ModelRouter({
+      default: { chat: vi.fn() } as unknown as ModelClient,
+      fallbackChain: [],
+    });
+
+    const labels = router.getAllLabels();
+    expect(labels).toEqual({});
+
+    router.setClient('fast', { chat: vi.fn() } as unknown as ModelClient, 'fast-tier');
+    router.setClient('complex', { chat: vi.fn() } as unknown as ModelClient, 'complex-tier');
+
+    const allLabels = router.getAllLabels();
+    expect(allLabels).toEqual({
+      fast: 'fast-tier',
+      complex: 'complex-tier',
+    });
+  });
+
+  it('constructor accepts initial labels', async () => {
+    const mockClient1 = { chat: vi.fn() } as unknown as ModelClient;
+    const mockClient2 = { chat: vi.fn() } as unknown as ModelClient;
+
+    const router = new ModelRouter({
+      default: mockClient1,
+      fast: mockClient2,
+      fallbackChain: [],
+      labels: {
+        default: 'default-tier',
+        fast: 'fast-tier',
+      },
+    });
+
+    expect(router.getClient('default')).toBe(mockClient1);
+    expect(router.getClient('fast')).toBe(mockClient2);
+    expect(router.getLabel('default')).toBe('default-tier');
+    expect(router.getLabel('fast')).toBe('fast-tier');
+    expect(router.getLabel('complex')).toBe('unknown');
+
+    await router.chat({ messages: [{ role: 'user', content: 'Hi' }] }, 'fast');
+
+    expect(mockClient2.chat).toHaveBeenCalled();
+  });
+
+  it('chat uses the new client after setClient', async () => {
+    const mockClient1 = { chat: vi.fn() } as unknown as ModelClient;
+    const mockClient2 = { chat: vi.fn() } as unknown as ModelClient;
+
+    const router = new ModelRouter({
+      default: mockClient1,
+      fast: { chat: vi.fn() } as unknown as ModelClient,
+      fallbackChain: [],
+      labels: {
+        fast: 'original-fast',
+      },
+    });
+
+    const initialFastClient = router.getClient('fast');
+    expect(initialFastClient).toBeDefined();
+    await router.chat({ messages: [{ role: 'user', content: 'Test' }] }, 'fast');
+
+    expect(initialFastClient!.chat).toHaveBeenCalled();
+    expect(initialFastClient!.chat).toHaveBeenCalledTimes(1);
+
+    router.setClient('fast', mockClient2, 'fast-replaced');
+
+    const newFastClient = router.getClient('fast');
+    await router.chat({ messages: [{ role: 'user', content: 'Test' }] }, 'fast');
+
+    expect(newFastClient!.chat).toHaveBeenCalled();
+    expect(newFastClient!.chat).toHaveBeenCalledTimes(1);
+    expect(initialFastClient!.chat).toHaveBeenCalledTimes(1);
+  });
+});

src/models/router.ts

@@ -11,10 +11,12 @@ export interface ModelRouterConfig {
   local?: ModelClient;
   fallbackChain: ModelClient[];
   retryConfig?: RetryConfig;
+  labels?: Partial<Record<ModelTier, string>>;
 }
 
 export class ModelRouter implements ModelClient {
   private clients: Map<ModelTier, ModelClient>;
+  private labels: Map<ModelTier, string>;
   private defaultClient: ModelClient;
   private fallbackChain: ModelClient[];
   private currentTier: ModelTier = 'default';
@@ -23,6 +25,7 @@ export class ModelRouter implements ModelClient {
 
   constructor(config: ModelRouterConfig) {
     this.clients = new Map();
+    this.labels = new Map();
     this.defaultClient = config.default;
     this.fallbackChain = config.fallbackChain;
     this.retryConfig = config.retryConfig;
@@ -31,6 +34,14 @@ export class ModelRouter implements ModelClient {
     if (config.fast) this.clients.set('fast', config.fast);
     if (config.complex) this.clients.set('complex', config.complex);
     if (config.local) this.clients.set('local', config.local);
+
+    if (config.labels) {
+      for (const tier of ['fast', 'default', 'complex', 'local'] as ModelTier[]) {
+        if (config.labels[tier]) {
+          this.labels.set(tier, config.labels[tier]);
+        }
+      }
+    }
   }
 
   setTier(tier: ModelTier): boolean {
@@ -141,4 +152,21 @@ export class ModelRouter implements ModelClient {
   getLocalProviderName(): string | undefined {
     return this.localProviderName;
   }
+
+  setClient(tier: ModelTier, client: ModelClient, label: string): void {
+    this.clients.set(tier, client);
+    this.labels.set(tier, label);
+  }
+
+  getLabel(tier: ModelTier): string {
+    return this.labels.get(tier) ?? 'unknown';
+  }
+
+  getAllLabels(): Record<string, string> {
+    const result: Record<string, string> = {};
+    for (const tier of this.labels.keys()) {
+      result[tier] = this.labels.get(tier) ?? 'unknown';
+    }
+    return result;
+  }
 }