feat(cursor): migrate remote sessions to ACP with model/variant pickers (#799)

* feat(cli,web,hub): migrate Cursor remote sessions to ACP with model/effort pickers

Move stream-json remote launcher to legacy path and add ACP launcher with
set_config_option model/mode sync, optimistic keepalive on config changes, and
shared catalog caching. Web gets dual base/effort Cursor pickers for session and
new-session flows; hide composer status bar when Cursor sends no usage_update.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(cli,web,shared): Cursor model picker — ACP wires + CLI sku variants

Enrich the web/mobile picker with agent --list-models SKUs grouped under
ACP wire bases, fix session-open base highlight, and keep catalog discovery
safe while the ACP transport holds the CLI lock.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(cursor-acp): apply ACP default model when web resets to Default

Web sends model: null for Default; push session/set_config_option with the
ACP default[] wire so Cursor backend matches hub state. Regression tests
for setModel(null) and applyModelConfig(null).

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(acp): clear stale agent-acp lock when owning process is gone

Check lock pid with signal 0; remove orphaned lock dirs after SIGKILL or
crash so listCursorModels can run cold probes again. Regression tests for
guard and catalog discovery.

Co-authored-by: Cursor <cursoragent@cursor.com>

* test(cursor): use live pid for ACP lock handler tests

Stale-lock cleanup clears dead pids; handler tests must simulate an
active lock with the current process pid to avoid cold probes/timeouts.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(acp): scope agent CLI lock guard to Cursor agent command only

Gemini/OpenCode/Kimi ACP sessions must not register agent-acp-active;
that blocked listCursorModels while unrelated backends were running.

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(hub,web): reject Cursor model changes for local sessions

Hub returns 409 when controlledByUser is set, matching Codex. Web hides
model and variant pickers for local Cursor sessions so users do not hit
a dead RPC path. Document pre-push-review in AGENTS.md.

Verified: bun typecheck; bun run test (919 cli + 243 hub + 768 web + 46 shared).
Co-authored-by: Cursor <cursoragent@cursor.com>

* fix(web): send stable ids for Cursor ask_question replies

Parse and submit question.id and option.id so ACP receives keys like
{ approach: ['a'] } instead of index/label. Verified: bun typecheck && bun run test.

Co-authored-by: Cursor <cursoragent@cursor.com>

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

docs/guide/cursor.md

@@ -41,12 +41,12 @@ Set mode via `--mode` flag or change from the web UI during a session.
 ## Modes
 
 - **Local mode** - Run `hapi cursor` from terminal. Full interactive experience.
-- **Remote mode** - Spawn from web/phone when no terminal. Uses `agent -p` with `--output-format stream-json` and `--trust`. Each user message spawns one agent process; session continues via `--resume`.
+- **Remote mode** - Spawn from web/phone when no terminal. New Cursor sessions use `agent acp` with HAPI permission approval, plan/question UI, and richer tool updates. Legacy sessions created before the ACP migration may still resume via the old `agent -p` stream-json path temporarily.
 
 ## Limitations
 
-- **Tool approval** - In remote mode, `--trust` is used; tools run without per-request approval. Use `--yolo` for full bypass.
-- **Session resume** - Pass `--resume <chatId>` or `--continue` to resume. Use `agent ls` to list previous chats and get chat IDs.
+- **Legacy sessions** - Cursor sessions created before the ACP migration can still resume temporarily via stream-json. Start a new Cursor session to get ACP permissions, plans, todos, and question support.
+- **Session resume** - ACP sessions resume through `session/load`. Old stream-json `session_id` values are not loadable via ACP; those sessions keep using the legacy path until you start fresh.
 
 ### Headless safety: AskQuestion behavior