feat(runner): add Cursor CLI as a new runner provider

[jeremyeder]

Summary

• Adds Cursor CLI as a third runner provider alongside Claude Code and Gemini CLI, feature-gated behind runner.cursor-cli.enabled (workspace-scoped Unleash flag)
• New ag_ui_cursor_cli package: NDJSON parser for the Cursor stream-json event format, AG-UI protocol adapter (CursorCLIAdapter) following the same pattern as the Gemini CLI adapter
• New ambient_runner.bridges.cursor_cli package: CursorCLIBridge (subclasses PlatformBridge), CursorSessionWorker/CursorSessionManager (async subprocess management with per-thread locks, TTL eviction, session-ID persistence across pod restarts), auth helper, MCP config writer that merges into .cursor/mcp.json
• Registry, feature flag, model list, Dockerfile install block, and GHA tool-version tracking all updated

Design notes

• The Cursor CLI stream-json event format is based on documentation research; parse_event() carries a NOTE comment flagging this as unverified against a real binary
• CURSOR_CLI_VERSION ARG in the Dockerfile is documentation-only — the upstream curl installer does not accept a version argument; the GHA sanity check explicitly excludes it with a comment
• Session IDs are persisted to cursor_session_ids.json and restored on pod restart for conversation continuity
• Platform secrets are stripped via _CURSOR_ENV_BLOCKLIST before spawning the agent binary

Test plan

• Enable runner.cursor-cli.enabled flag for a workspace
• Create a session with a cursor:* model and verify the agent binary is invoked with the expected flags
• Verify NDJSON stream is parsed and AG-UI events are emitted correctly
• Verify session ID is persisted and --resume is used on subsequent turns
• Verify platform secrets are not leaked to the Cursor CLI process environment
• Verify MCP servers are written to .cursor/mcp.json and merged with existing config
• Disable the flag and verify cursor sessions are rejected at the bridge layer

🤖 Generated with Claude Code

[netlify]

✅ Deploy Preview for cheerful-kitten-f556a0 canceled.

Name	Link
🔨 Latest commit	ba2f8cd
🔍 Latest deploy log	https://app.netlify.com/projects/cheerful-kitten-f556a0/deploys/69e7c57d18a32a0009f4c0f5

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 17635ffc-6e3d-40f5-8eb9-da04bf47a6bb

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

✨ Simplify code

• Create PR with simplified code

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}