fix(cursor): repair crashing attribution suppression and register cursor for crew-dispatch

[Quidge]

Intent

Fix two defects in the freshly-merged cursor-agent crew harness adapter (Quidge/firstmate PR #9), which is non-functional because cursor crashes at launch. Scope is strictly these two defects plus their tests/docs; explicitly NOT adding context7/MCP wiring (that is a separate task). No behavior change for any existing harness - changes are cursor-scoped and additive/corrective.

Defect 1 (fatal): fm-spawn wrote a per-worktree project .cursor/cli.json of {"version":1,"attribution":{...}} to suppress cursor's default commit/PR agent-attribution trailer (Co-authored-by: Cursor cursoragent@cursor.com). cursor-agent validates that PROJECT config against a strict schema that accepts ONLY permissions, so it rejects version/attribution with "Unrecognized key(s)" and drops the pane to bash; the worker never starts. The attribution block is valid only in the GLOBAL ~/.cursor/cli-config.json, which cursor rewrites at runtime and shares across concurrent workers, so a global edit is unsafe; and there is no CLI flag or env var to disable attribution (verified empirically against cursor-agent 2026.07.23-e383d2b's bundled zod schema). Chosen fix: a per-task git commit-msg hook under state/.cursor-git-hooks/ that strips the Cursor co-author trailer, reached ONLY by the cursor worker via env-injected core.hooksPath (GIT_CONFIG_* exported before launch on the same channel as GOTMPDIR). This choice is deliberate because git resolves a linked worktree's hooks from the shared common .git/hooks dir (empirically proven), so a per-worktree hooks dir would not fire, whereas an env-injected core.hooksPath does. Deliberate constraints, all met: does not crash the launch; touches NO cursor config; makes no destructive or racy global-config edit; installed by fm-spawn and removed at teardown; strips only Co-authored-by trailers in cursor's agent namespace (@cursor.com/@cursor.sh) so it never interferes with legitimate commit messages or human co-authors. Mandatory live proof was performed against a real cursor-agent worker in a throwaway git repo (interactive launch in a separate tmux window, since a crewmate cannot launch the cursor TUI in its own pane): the old .cursor/cli.json reproducibly crashes the launch ("Unrecognized key(s)", pane drops to bash), and the new mechanism launches clean (pane_current_command=cursor-agent) while the worker's OWN autonomous git commit --trailer "Co-authored-by: Cursor <cursoragent@cursor.com>" lands a commit whose body has NO trailer - proving the hook is the sole reason it is absent. Evidence recorded in docs/verification/runtime-backends.md. A unit test alone is intentionally treated as necessary-but-not-sufficient here because the trailer is server-driven and only a real worker emits the --trailer commit.

Defect 2 (minor): cursor was missing from the crew-dispatch verified-harness set in fm-bootstrap.sh, so a valid config/crew-dispatch.json routing work to cursor was wrongly rejected as "unverified harness: cursor". Added cursor to that verified set, and (for validator correctness) to the no-effort branch of the dispatch effort check, since cursor has no effort flag - exactly like opencode/kimi - so a cursor profile carrying an effort is correctly rejected. Deliberate scoping decision: cursor is intentionally NOT added to the remote-secondmate lists (fm-remote-secondmate-control.sh, fm-remote-doctor.sh) or the secondmate-liveness gate in fm-bootstrap.sh, because cursor was verified only as a LOCAL crewmate, not for remote-secondmate use; those omissions are correct and preserved.

Tests/docs: reworked the cursor-harness attribution tests to cover the commit-msg hook behavior (strips the Cursor trailer, preserves human co-authors and clean messages byte-for-byte) and the core.hooksPath env wiring, and to assert the crash-inducing .cursor/cli.json is no longer written; added crew-dispatch cursor validation cases; corrected the attribution mechanism description in harness-adapters SKILL.md; recorded the live crash/fix proof in docs/verification/runtime-backends.md. All colocated tests, shellcheck 0.11.0, and the doc-audience check pass.

What Changed

• Replace the per-worktree .cursor/cli.json attribution config — which cursor-agent rejects against its project-config schema and crashes the launch on — with a per-task commit-msg hook under state/<id>.cursor-git-hooks/ that strips only cursor-agent's Co-authored-by: <…@cursor.com/.sh> trailer; fm-spawn.sh writes and activates it via env-injected GIT_CONFIG_*/core.hooksPath (gated to non-secondmate cursor workers), and fm-teardown.sh removes the hook dir and drops all .cursor/cli.json cleanup.
• Add cursor to the crew-dispatch verified-harness set in fm-bootstrap.sh, and to the no-effort branch of the dispatch effort check (alongside opencode/kimi) so a cursor profile carrying an effort flag is correctly rejected.
• Rework the cursor-harness tests to cover the trailer-stripping hook, human/clean-message preservation, and core.hooksPath wiring, assert .cursor/cli.json is no longer written, add crew-dispatch cursor validation cases, and update the attribution-mechanism description in the harness-adapters SKILL plus the live crash/fix proof in the runtime-backends doc.

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ **Rebase** - passed

✅ **Review** - completed

✅ **Test** - passed

✅ **Document** - passed

✅ **Lint** - passed

✅ **Push** - passed