b6efd89ae5
Add a supervised Cursor CLI runtime for routed Cursor model sessions. - Stream Cursor prompt output into Fusion session callbacks with resume support. - Support Windows Cursor shims, inactivity-based supervision, and cursor-agent to cursor fallback execution. - Route Cursor CLI models through the bundled plugin and document the runtime contract. Files changed: .changeset/fn-9097-cursor-cli-runtime.md | 7 ++ docs/cursor-cli-contract.md | 21 ++++ docs/settings-reference.md | 4 +- .../cli-runtime-routing-conformance.test.ts | 11 +- .../engine/src/agents/agent-session-helpers.ts | 6 +- packages/engine/src/agents/cli-provider-routing.ts | 27 ++--- plugins/fusion-plugin-cursor-runtime/README.md | 21 ++++ plugins/fusion-plugin-cursor-runtime/package.json | 1 + .../src/__tests__/cli-spawn.test.ts | 25 ++++- .../src/__tests__/prompt-transport.test.ts | 58 ++++++++++ .../src/__tests__/runtime-adapter.test.ts | 44 +++++--- .../src/__tests__/stream-parser.test.ts | 12 +++ .../fusion-plugin-cursor-runtime/src/cli-spawn.ts | 57 +++++++++- plugins/fusion-plugin-cursor-runtime/src/index.ts | 4 +- .../src/prompt-transport.ts | 120 +++++++++++++++++++++ .../src/runtime-adapter.ts | 59 ++++++---- .../src/stream-parser.ts | 43 ++++++++ plugins/fusion-plugin-cursor-runtime/src/types.ts | 18 ++-- pnpm-lock.yaml | 3 + 19 files changed, 458 insertions(+), 83 deletions(-) Fusion-Task-Id: FN-9097 Fusion-Task-Lineage: a4eed861-6059-4528-9f80-3426f5ccad58 Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>
fusion-plugin-cursor-runtime
Cursor CLI-backed provider/runtime plugin for Fusion.
Contract summary
- Provider ID:
cursor-cli - Binary probes:
cursor-agent, thencursor - Expected failure states: missing binary, missing Cursor IDE install, locked macOS keychain, unauthenticated runtime
- Model discovery:
cursor-agent models(plain textid - Labeloutput; no--jsonsupport) with header/tip/empty-state filtering, dedupe, and fallback metadata - Auth status:
cursor-agent status --format json(isAuthenticated), probed against the same candidate binary that succeeded--version
Notes
Status/auth and model discovery behavior follows docs/cursor-cli-contract.md.
External Integration Evidence
- Canonical upstream repository: Cursor CLI is closed-source and has no canonical upstream source repository. Its public issue tracker is https://github.com/cursor/cursor.
- Docs / homepage: https://cursor.com/docs/cli/overview
- Release / download:
curl https://cursor.com/install -fsS | bash(macOS/Linux/WSL), orirm 'https://cursor.com/install?win32=true' | iex(Windows PowerShell). - Binary:
cursor-agent - Checksum:
upstream-pending-verification; Cursor publishes no versioned checksum manifest. Verified local provenance:2026.08.11-e8db854on 2026-08-15.
Execution transport contract
Fusion runs one supervised cursor-agent --print --output-format stream-json turn per prompt. The prompt is supplied on stdin, the process cwd is the Fusion task worktree, and the init event confirmed that cwd is the Cursor workspace without a --workspace argument. Stream JSON emits init, thinking, assistant, tool_call, and terminal result events; session IDs are retained with --resume on the next turn.
| Fusion tool mode | Cursor flags |
|---|---|
coding |
--force --trust |
readonly or unset |
--mode plan --trust |
--print already grants built-in write and shell tools. --force controls approval, so it is limited to coding sessions whose cwd is Fusion's isolated task worktree. Fusion does not use --auto-review, worktree, add-dir, MCP approval, plugin-dir, or sandbox override flags. Fusion fn_* tools are not bridged into Cursor; Cursor uses only its own built-in tools.
All turns use superviseSpawn with a finite lifetime. The Windows prompt transport prefers a direct executable; .cmd/.bat shims validate and reject cmd metacharacters before a quoted cmd launch, .ps1 uses PowerShell -File, and unknown extensions fail loudly. PI_CURSOR_CLI_FIRST_LINE_TIMEOUT_MS and PI_CURSOR_CLI_TIMEOUT_MS optionally tune cold-start and inactivity guards.