# 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 |
