Sækja opencode 1.15.9

Core
Improvements
- Redesigned the diff viewer with a file tree and refreshed layout.
Bugfixes
- Return to the previous screen when closing the diff viewer.
- Show clearer errors when a default model is invalid or unavailable.
- Surface missing PTY session errors instead of failing generically.
- Improve diff viewer empty states and context handling.
- Show clearer errors when a skill invocation fails as expected.
- Show clearer errors when an installation upgrade fails.
- Show clearer project not found errors from the HTTP API.
- Return PTY error bodies from the HTTP API.
- Enable the diff viewer by default.
- Return MCP server not found errors from the HTTP API.
- Let MCP OAuth configs set a callback port and include configured scopes in client metadata. (@sebin)
- Use working Vertex Anthropic endpoints for us and eu multi-region setups. (@JPFrancoia)
- Return session busy error bodies from the HTTP API.
- Preserve native reasoning continuation metadata across turns.
TUI
Improvements
- Copy the current worktree path from the command palette.
Bugfixes
- Refine diff viewer keyboard shortcuts.
- Restore question prompt key handling.
- Keep the spinner color aligned with the active agent. (@OpeOginni)
Desktop
Improvements
- Move tab navigation into the title bar and tighten session tab shortcuts.
- Show session status in the title bar.
Bugfixes
- Extract user codes correctly from callback URLs that contain multiple colons. (@OpeOginni)
- Debounce VCS refreshes to reduce session page churn.
Thank you to 4 community contributors:
- @vglafirov:
- chore(deps): bump gitlab-ai-provider to 6.7.0 (#28218)
- @OpeOginni:
- fix(opencode): update spinner color logic (#28032)
- fix(desktop): correct user code extraction when URL contains colons (#28837)
- @JPFrancoia:
- fix(vertex): Vertex (Antropic) provider: use .rep.googleapis.com for continental multi-region endpoints (us, eu) (#28347)
- @sebin:
- fix(mcp): include scope in clientMetadata and add callbackPort option (#28810)