feat(babysit-lane): adopt the merge lane with drain mode at worker tier

[kyle-sexton]

Summary

Adds the team-tracked .claude/source-control.md layer with the babysit-loop lane keys (drain stop mode, worker tier, c2-mechanical merge rung, 30-minute grace window). Per the loop-lane convention's baseline-activation rule, this reviewed PR is the recorded human-ratified lane adoption for ci-workflows — the act that activates the baseline merge rung (gate-proven C2-mechanical PRs only; everything else stays human merge). Without this file, the lane runs with every merge human-only.

Phase B3 pre-requisite of the work-loop plan (claude-code-plugins docs/topics/ci-workflows-work-loop/babysit-PLAN.md).

Test plan

• markdownlint clean
• Key names match the seam's key table (plugins/source-control/reference/config-resolution.md)

Related

No linked issue.

[claude]

Claude finished @kyle-sexton's task in 3m 50s —— View job

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PR Review

• Gather context
• Read changed files
• Check key names against seam's key table
• Review PR for correctness and alignment
• Post findings

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Summary

This PR's actual diff — +2/-2 advancing Phase 5 and Phase 6 from [TODO] to [DONE] in PLAN.md — is clean and correct in isolation. However, there are four issues that need to be addressed before merge.

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Finding 1 — Blocking: Duplicate of already-merged work

The changes in this PR are byte-for-byte identical to commit ffc93ed (PR #1183), which is already on main. Both advance the same two lines in PLAN.md:

-### Phase 5: ci-workflows tracker binding [TODO]
+### Phase 5: ci-workflows tracker binding [DONE]
...
-### Phase 6: standards lease-activation PR draft [TODO]
+### Phase 6: standards lease-activation PR draft [DONE]

Merging this PR would produce no net change to PLAN.md on main. The branch appears to have been opened from the shared parent commit 3973d0a, parallel to the already-merged ffc93ed.

Action needed: Confirm whether this PR should be closed as superseded by #1183, or rebased onto current main if there is distinct content intended here.

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Finding 2 — Blocking: PR description and title don't match the diff

PR title: feat(babysit-lane): adopt the merge lane with drain mode at worker tier

PR body: "Adds the team-tracked .claude/source-control.md layer with the babysit-loop lane keys (drain stop mode, worker tier, c2-mechanical merge rung, 30-minute grace window)."

Actual diff: Only docs/topics/ci-workflows-work-loop/PLAN.md, +2/-2 (phase tag strings).

The source-control.md file (in this repo) does not contain any babysit_loop_* keys, and no changes to it appear in this PR's diff. The keys the body references — babysit_loop_stop_mode, babysit_loop_tier, babysit_loop_merge, babysit_loop_grace_window_minutes — are defined in plugins/source-control/reference/config-resolution.md but are absent from both this PR and the current .claude/source-control.md.

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Finding 3 — Architecture concern: Lane activation must happen in the target repository

config-resolution.md L113–121 states:

"Landing loop-lane keys in that tracked file — a reviewable PR in the target repository — is the recorded, human-ratified lane-enabling act."

The target repository for the ci-workflows babysit lane is melodic-software/ci-workflows. The lane adoption PR (adding babysit_loop_* keys to ci-workflows/.claude/source-control.md) must be filed and merged there, not here. A PR in claude-code-plugins cannot serve as the "recorded human-ratified lane adoption for ci-workflows" under the seam's own contract.

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Finding 4 — Minor: Conventional Commits type mismatch

The PR title uses feat(babysit-lane) but the underlying commit is docs(topics): advance work-loop plan Phase 5 and Phase 6 tags to DONE. Since this repo squash-merges (PR title becomes the commit subject per .github/workflows/pr-title.yml), merging would record this as a feat in history for what is a pure documentation update. The title should be docs(topics): ... to match the commit's actual scope.

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Finding 5 — Note: Phase B3 is still [TODO] in babysit-PLAN.md

The PR describes itself as a "Phase B3 pre-requisite." Phase B3 (ci-workflows drain instantiation) is still marked [TODO] in babysit-PLAN.md L221 and is not addressed by this PR's diff. This is consistent with the PR's stated intent (a pre-requisite for B3, not B3 itself), but worth noting since the PR title implies the lane adoption is complete.

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Recommended path forward

1. Close this PR if docs(topics): advance work-loop plan Phase 5 and Phase 6 tags #1183 already captured the PLAN.md phase tag intent.
2. File the actual lane adoption PR — the one adding babysit_loop_stop_mode, babysit_loop_tier, babysit_loop_merge, and babysit_loop_grace_window_minutes to melodic-software/ci-workflows/.claude/source-control.md — in the ci-workflows repository, per the seam's activation contract.
3. Once that PR merges, advance Phase B3 in babysit-PLAN.md here.

[kyle-sexton]

Created accidentally against the wrong repository (working-directory drift); the real change is a ci-workflows adoption file. No content lost — the single commit here was already merged via #1183.