feat: Multi-Account OAuth Rotation with Settings UI and CLI Enhancements

[mguttmann]

Summary

Implements comprehensive multi-account OAuth support with automatic rate limit rotation, manual account switching, and a new Settings menu for the desktop app.

Closes #9068

Changes

Backend - OAuth Pool Enhancements

• Auth.OAuthPool.setActive() - Manually switch active OAuth account
• Auth.OAuthPool.snapshot() - Returns activeID for credential selection
• rotating-fetch.ts - Prefers activeID while preserving auto-rotation on 429
• fetchAnthropicUsage() - Respects provider.active[namespace]
• getAccounts() - Correctly identifies active account

API

• POST /auth/active - Switch active account, returns updated usage data

Desktop App

New Settings Menu (DialogSettings):

• Providers Tab: Connected providers, add new with search
• Provider Detail: Account list, usage bars, switch functionality
• About Tab: GitHub, docs, Discord, keyboard shortcuts

Context Panel:

• Anthropic Rate Limits section (5h, 7d-all, 7d-sonnet bars)
• Account switch buttons
• Only visible for Anthropic sessions

CLI

• opencode auth usage: Per-account usage with rate limits
• opencode auth switch: Interactive account switching
• opencode auth list: Shows account counts
• All lists sorted alphabetically

Auto-Rotation Flow

1. Request with activeID (manually selected or first available)
2. On 429 rate limit:
   - Account gets cooldownUntil
   - Account moved to back of queue
   - Loop continues with next candidate
3. Next available account used automatically

Files Changed

Package	File	Description
opencode	auth/index.ts	Core OAuth pool functions
opencode	auth/rotating-fetch.ts	Credential selection logic
opencode	server/server.ts	/auth/active endpoint
opencode	cli/cmd/auth.ts	CLI commands
app	dialog-settings.tsx	New settings dialog
app	session-context-tab.tsx	Context panel usage section
app	layout.tsx	Settings button
sdk	sdk.gen.ts, types.gen.ts	Regenerated

Testing

CLI

opencode auth list      # Shows providers with account counts
opencode auth usage     # Shows per-account stats with rate limits
opencode auth switch    # Interactive account switching

Desktop

1. Click ⚙️ Settings button → Providers tab
2. Click connected provider → View accounts and usage
3. Switch accounts → Verify bars update
4. Open Anthropic session → Context panel shows rate limits

Limitations

• Usage statistics: Anthropic only (OAuth API limitation)
• Multi-account: Anthropic, OpenAI, GitHub Copilot
• Other providers: Contributions welcome

Checklist

• [x] Backend OAuth pool enhancements
• [x] API endpoint for account switching
• [x] Desktop Settings menu
• [x] Context panel integration
• [x] CLI commands
• [x] Alphabetical sorting
• [x] Auto-rotation preserved
• [x] Local state updates (no full refresh on switch)