fix(kanban): name failed git operation and returncode in survivor hold

[Kyzcreig]

Summary

• Re-port fix(kanban): name the git subcommand and returncode in survivor holds #859 onto current fork/main by content. _git() now persists the Git subcommand and returncode in a survivor hold, not the opaque git inspection failed message.
• Reuse main's _git(input=) signature and existing redacted warning from fix(kanban): log git's returncode and stderr when survivor capture fails #856 rather than duplicating stderr handling. _record() and its post-kanban: reclamation consults the RECORDED survivor instead of re-deriving from stale bases #842/fix(kanban): bind an explicit survivor claim to the card that names it #848/fix(kanban): close the 4 P1 FleetReview recorded on #848's head 0757be86 #886 paths are untouched.
• Adapt the existing real missing-workspace and hermetic redacted-stderr tests in test_kanban_survivor_authority.py to assert the new reason and ensure credential-bearing stderr stays out of the reason and log. The separate test introduced in fix(kanban): name the git subcommand and returncode in survivor holds #859 is redundant with these tests on main.

Verification

• RED on main with adapted tests: 2 failed (both reasons were survivor_unavailable: git inspection failed).
• GREEN on branch: PYTHONPATH="$PWD" HERMES_HOME=/tmp/t_1e7a5864-test ~/.hermes/hermes-agent/.venv/bin/python -P -m pytest -q tests/hermes_cli/test_kanban_survivor_authority.py -k 'git_failure_' -o addopts='' → 2 passed, 7 deselected.
• PYTHONPATH="$PWD" HERMES_HOME=/tmp/t_1e7a5864-test ~/.hermes/hermes-agent/.venv/bin/python -P -m pytest -q tests/hermes_cli/test_kanban_survivor.py tests/hermes_cli/test_kanban_survivor_authority.py tests/hermes_cli/test_kanban_survivor_broken_object_store.py -o addopts='' → 56 passed in 65.54s.
• git diff --check clean.

Supersedes #859. This branch is independent of the in-flight #924 survivor port: coordinate merge order with Apollo after Argus records #924's review.

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[Kyzcreig]

🤖 merged-by: apollo · lane: t_1e7a5864 · gate: BYPASS: FleetReview disabled fleet-wide (Ace 2026-09-22); gate = kanban Argus-APPROVED review + CI green + 0 conflicts · why: Argus APPROVED (PASS-WITH-CAVEATS) @ a214408: kanban survivor names the failed git op + rc; diagnostic RED on fork/main GREEN on PR; CI green

[Kyzcreig]

🤖 merged-by: apollo · lane: t_1e7a5864 · gate: BYPASS: FleetReview disabled fleet-wide (Ace 2026-09-22); gate = kanban Argus-APPROVED review + CI green + 0 conflicts · why: Argus APPROVED (PASS-WITH-CAVEATS) @ a214408: kanban survivor names the failed git op + rc; diagnostic RED on fork/main GREEN on PR; CI green; undrafted by Apollo