feat: Google's gemini-cli integration (#422)

* feat: integrate Gemini AI agent provider

- Core Backend: Ported gemini-cli.js and gemini-response-handler.js to establish the CLI bridge. Registered 'gemini' as an active provider within index.js.
- Core Frontend: Extended QuickSettingsPanel.jsx, Settings.jsx, and AgentListItem.jsx to render the Gemini provider option, models (gemini-pro, gemini-flash, etc.), and handle OAuth states.
- WebSocket Pipeline: Added support for gemini-command executions in backend and payload processing of gemini-response and gemini-error streams in useChatRealtimeHandlers.ts. Resolved JSON double-stringification and sessionId stripping issues in the transmission handler.
- Platform Compatibility: Added scripts/fix-node-pty.js postinstall script and modified posix_spawnp calls with sh -c wrapper to prevent ENOEXEC and MacOS permission errors when spawning the gemini headless binary.
- UX & Design: Imported official Google Gemini branding via GeminiLogo.jsx and gemini-ai-icon.svg. Updated translations (chat.json) for en, zh-CN, and ko locales.

* fix: propagate gemini permission mode from settings to cli

- Added Gemini Permissions UI in Settings to toggle Auto Edit and YOLO modes
- Synced gemini permission mode to localStorage
- Passed permissionMode in useChatComposerState for Gemini commands
- Mapped frontend permission modes to --yolo and --approval-mode options in gemini-cli.js

* feat(gemini): Refactor Gemini CLI integration to use stream-json

- Replaced regex buffering text-system with NDJSON stream parsing
- Added fallback for restricted models like gemini-3.1-pro-preview

* feat(gemini): Render tool_use and tool_result UI bubbles

- Forwarded gemini tool NDJSON objects to the websocket
- Added React state handlers in useChatRealtimeHandlers to match Claude's tool UI behavior

* feat(gemini): Add native session resumption and UI token tracking

- Captured cliSessionId from init events to map ClaudeCodeUI's chat sessionId directly into Gemini's internal session manager.
- Updated gemini-cli.js spawn arguments to append the --resume proxy flag instead of naively dumping the accumulated chat history into the command prompt.
- Handled result stream objects by proxying total_tokens back into the frontend's claude-status tracker to natively populate the UI label.
- Eliminated gemini-3 model proxy filter entirely.

* fix(gemini): Fix static 'Claude' name rendering in chat UI header

- Added "gemini": "Gemini" translation strings to messageTypes across English, Korean, and Chinese loc dictionaries.
- Updated AssistantThinkingIndicator and MessageComponent ternary checks to identify provider === 'gemini' and render the appropriate brand label instead of statically defaulting to Claude.

* feat: Add Gemini session persistence API mapping and Sidebar UI

* fix(gemini): Watch ~/.gemini/sessions for live UI updates

Added the .gemini/sessions directory to PROVIDER_WATCH_PATHS so that Chokidar emits projects_updated websocket events when new Gemini sessions are created or modified, fixing live sidebar updates.

* fix(gemini): Fix Gemini authentication status display in Settings UI

- Injected 'checkGeminiAuthStatus' into the Settings.jsx React effect hook so that the UI can poll and render the 'geminiAuthStatus' state.
- Updated 'checkGeminiCredentials()' inside server/routes/cli-auth.js to read from '~/.gemini/oauth_creds.json' and '~/.gemini/google_accounts.json', resolving the email address correctly.

* Use logo-only icon for gemini

* feat(gemini): Add Gemini 3 preview models to UI selection list

* Fix Gemini CLI session resume bug and PR #422 review nitpicks

* Fix Gemini tool calls disappearing from UI after completion

* fix(gemini): resolve outstanding PR #422 feedback and stabilize gemini CLI timeouts

* fix(gemini): resolve resume flag and shell session initialization issues

This commit addresses the remaining PR comments for the Gemini CLI integration:

- Moves the `--resume` flag logic outside the prompt command block, ensuring Gemini sessions correctly resume even when a new prompt isn't passed.

- Updates `handleShellConnection` to correctly lookup the native `cliSessionId` from the internal `sessionId` when spawning Gemini sessions in a plain shell.

- Refactors dynamic import of `sessionManager.js` back to a native static import for code consistency.

* chore: fix TypeScript errors and remove gemini CLI dependency

* fix: use cross-spawn on Windows to resolve gemini.cmd correctly

---------

Co-authored-by: Haileyesus <118998054+blackmammoth@users.noreply.github.com>

shared/modelConstants.js

@@ -65,3 +65,22 @@ export const CODEX_MODELS = {
 
   DEFAULT: 'gpt-5.3-codex'
 };
+
+/**
+ * Gemini Models
+ */
+export const GEMINI_MODELS = {
+  OPTIONS: [
+    { value: 'gemini-3.1-pro-preview', label: 'Gemini 3.1 Pro Preview' },
+    { value: 'gemini-3-pro-preview', label: 'Gemini 3 Pro Preview' },
+    { value: 'gemini-3-flash-preview', label: 'Gemini 3 Flash Preview' },
+    { value: 'gemini-2.5-flash', label: 'Gemini 2.5 Flash' },
+    { value: 'gemini-2.5-pro', label: 'Gemini 2.5 Pro' },
+    { value: 'gemini-2.0-flash-lite', label: 'Gemini 2.0 Flash Lite' },
+    { value: 'gemini-2.0-flash', label: 'Gemini 2.0 Flash' },
+    { value: 'gemini-2.0-pro-exp', label: 'Gemini 2.0 Pro Experimental' },
+    { value: 'gemini-2.0-flash-thinking-exp', label: 'Gemini 2.0 Flash Thinking' }
+  ],
+
+  DEFAULT: 'gemini-2.5-flash'
+};