fix(bin): detect Grok 4.5 busy workers correctly

[sparkus]

Intent

Fix firstmate's stall detection for Grok 4.5 workers so firstmate can tell a stuck Grok 4.5 worker from a healthy one (both false negatives and false positives).

Confirmed live bug: harness-adapters and busy detection recorded busy as ASCII Ctrl+c:cancel in the keybind footer, but Grok 4.5 / Build 0.2.118 renders Esc:cancel instead (e.g. Shift+Tab:mode | Esc:cancel | Ctrl+x:shortcuts mid-turn; idle has no :cancel token). That made busy/idle classification wrong for every Grok 4.5 worker. Also recorded that interrupt is only Ctrl+C and that Esc only moves focus to scrollback and does NOT interrupt - false on 4.5; Escape DOES cancel the running turn (also verified Ctrl+C still cancels mid-turn).

Requirements:

• Verify both facts against running Grok Build before changing (done: live pane captures on 0.2.118).
• Make busy detection correct for BOTH the older Ctrl+c:cancel footer and 4.5's Esc:cancel, so a mixed fleet keeps working; do not simply swap one literal for another.
• Correct the interrupt fact in harness-adapters, including removing the explicit false Escape claim rather than softening it.
• Check bin/fm-tmux-lib.sh and anything else that consumes that signature (including fm-busy-lib.sh grok-regex fallback).
• Detection driven by matched patterns (ERE alternation of verified forms) rather than a single hard-coded literal, so the next rename is a data change.
• Stay inside detection and documentation fix; do not redesign supervision, the watcher, or the adapter contract.

Acceptance (executable tests where code allows):

• Running Grok 4.5 turn classified BUSY; idle classified IDLE (both directions).
• Older footer form still classifies correctly with its own test coverage.
• Interrupt documented in harness-adapters is the one that actually cancels on 4.5; false Escape claim removed.

What Changed

• Match both older Ctrl+c:cancel and Grok 4.5 Esc:cancel footers across tmux and Grok-specific busy detection while keeping idle footers classified correctly.
• Correct the Grok adapter documentation for current busy-footer and interrupt behavior, including Escape cancellation.
• Add regression coverage for older busy, Grok 4.5 busy, and Grok 4.5 idle captures across all affected consumers.

Risk Assessment

✅ Low: Captain, the change is narrowly scoped and consistently updates both Grok detection paths, preserves the older footer, correctly documents interruption, and adds busy/idle coverage without a source-verifiable regression.

Testing

No baseline test output was supplied. After correcting an evidence-command shell mismatch by rerunning under Bash, all targeted regression tests, direct captured-footer classification checks, documentation audit, scope audit, and final cleanliness check passed. This is CLI detection and documentation behavior, so screenshot evidence was not applicable.

Evidence: Grok busy/idle classification transcript

Older footer: busy grok-regex Grok 4.5 footer: busy grok-regex Grok 4.5 idle footer: idle grok-regex Obsolete interrupt claims: 0

Grok rendered-footer classification evidence
Target SHA: 6a68056408920adb8b11d324d3e7089a0177fea6
Configured Grok ERE: (Ctrl\+c|Esc):cancel

Older mid-turn footer
  rendered: Shift+Tab:mode  │  Ctrl+c:cancel  │  Ctrl+.:shortcuts
  stall classifier: busy grok-regex
  tmux delivery guard: busy
Grok 4.5 mid-turn footer
  rendered: Shift+Tab:mode  │  Esc:cancel  │  Ctrl+x:shortcuts
  stall classifier: busy grok-regex
  tmux delivery guard: busy
Grok 4.5 idle footer
  rendered: Shift+Tab:mode  │  Ctrl+x:shortcuts
  stall classifier: idle grok-regex
  tmux delivery guard: idle

Documented Grok interrupt fact
| Interrupt | single Escape cancels the running turn on Grok 4.5 (footer shows `Esc:cancel` mid-turn; verified 2026-08-02 on Build 0.2.118). A single `Ctrl+C` also cancels a running turn on 4.5. Prefer Escape when the live footer shows `Esc:cancel`. Escape is the cancel key mid-turn, not a scrollback-only focus move. |
Obsolete Escape-does-not-interrupt claims: 0

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

✅ **Review** - passed

✅ No issues found.

✅ **Test** - passed

✅ No issues found.

• bash tests/fm-busy-state.test.sh
• bash tests/fm-busy-adapter-wiring.test.sh
• bash tests/fm-crew-state.test.sh
• bash tests/fm-tmux-submit-busy.test.sh
• Under /bin/bash, sourced bin/fm-busy-lib.sh and bin/fm-tmux-lib.sh and classified older busy, Grok 4.5 busy, and Grok 4.5 idle captures through both consumers
• rg -n 'FM_TMUX_GROK_BUSY_REGEX_DEFAULT|fm_busy_grok_tail_busy|fm_pane_is_busy' bin/fm-tmux-lib.sh bin/fm-busy-lib.sh
• Searched tracked source for Esc.*only moves focus|does NOT interrupt and found no matches
• git status --short --untracked-files=all

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.