refactor(source-control): read the remaining babysit keys from docs/conventions/source-control.yaml #12285

Parent

Refs #5906

Blocks

• chore: drop the one-release .claude config reads and this repository's old config files #9737

Outcome

Sixteen source-control team keys whose only team home is .claude/source-control.md get one in
docs/conventions/source-control.yaml, with the legacy file read for a key the YAML lacks, for one release:

• nine loop-lane keys (babysit_loop_discovery_scope, babysit_loop_fixing, babysit_loop_thread_resolution,
  babysit_loop_draft_elevation, babysit_loop_barrier_overrides, babysit_loop_escalation,
  babysit_loop_cycle_budget, babysit_loop_no_progress_threshold, babysit_loop_trusted_internal_bot_logins),
  today "H2-only in the legacy file for now" (plugins/source-control/reference/config-resolution.md:46-51);
• the seven babysit-prs repository-policy keys (babysit_merge_method, babysit_merge_block_labels,
  babysit_extra_dependency_manager_logins, babysit_approval_downgrade_logins, babysit_skip_downgrade_logins,
  babysit_review_gate_context, babysit_ci_gateway_context), read today only from the target's default-branch
  legacy file (config-resolution.md:545-554, skills/babysit-prs/scripts/babysit_repo_config.py:4,36).

Two readers of babysit_loop_merge that cannot run without the legacy file move to the YAML too.

Decisions

• ADR 0064 Decision 1 and ADR 0075 fix 3: script-read team settings are YAML in docs/conventions/<concern>.yaml,
  validated by plugins/source-control/schemas/source-control.schema.json.
• ADR 0064 Decision 9: babysit keeps its own fetch of the target's default branch through the contents API, with no ref.
• ADR 0039 and config-resolution.md:566-611: the merge modes are unchanged. Hold lists are the add-only union with
  the userConfig fallback, babysit_skip_downgrade_logins is remove-only, and the review pair and trigger phrase stay
  userConfig-only.
• Migrate per-skill .claude config files to userConfig, one conventions doc, or the cascade (ADR 0018) #5906 (comment 2026-10-04): each reader keeps reading the old file for one release when the new file lacks the key.
• chore: drop the one-release .claude config reads and this repository's old config files #9737 record: once .claude/source-control.md is absent at the base SHA, babysit_loop_merge from the YAML sets
  the merge rung by itself (babysit_merge_policy.py:946-948 left this to the cleanup work). With both files, the
  lower value still binds.

Key interfaces

• plugins/source-control/schemas/source-control.schema.json, lib/convention-key.sh,
  skills/babysit-prs/scripts/babysit_repo_config.py and its fake, babysit_merge_policy.py.
• plugins/harness-config/skills/audit/scripts/audit-engine.sh:1369-1406, the unattended-lane signal.
• plugins/source-control/reference/config-resolution.md, docs/conventions/pr-pipeline/README.md:1079-1083.
• The model-read files for the nine loop keys, which have no script reader:
  plugins/source-control/skills/babysit-loop/SKILL.md, plugins/source-control/skills/babysit-loop/reference/cycle-shape.md
  and plugins/source-control/skills/babysit-loop/reference/no-progress-detector.md.

Done when

• plugins/source-control/schemas/source-control.schema.json defines the sixteen keys above, and scripts/check-convention-yaml.sh --check exits 0.
• scripts/run-test-file.sh plugins/source-control/skills/babysit-prs/scripts/tests/test_babysit_repo_config.py exits 0 with cases for: a remote YAML value wins over the legacy H2; a repository with only the legacy file still resolves; a YAML hold list unions with the userConfig hold list; a YAML babysit_skip_downgrade_logins only narrows the fallback set; a YAML the reader rejects is a repository config error with no fallback to the legacy file; a YAML carrying only one of the nine loop-lane keys counts as tracked adoption (merge default c2-mechanical).
• scripts/run-test-file.sh plugins/source-control/skills/babysit-prs/scripts/tests/test_babysit_merge_policy.py exits 0 with cases for: no legacy file and a YAML babysit_loop_merge sets the rung from the YAML; both files bind the lower value; neither file leaves the rung off.
• scripts/run-test-file.sh plugins/harness-config/skills/audit/scripts/audit-engine.test.sh exits 0 with a case where only docs/conventions/source-control.yaml sets babysit_loop_merge and the unattended lane is reported, and a case where the YAML carries only a non-merge loop-lane key and the unattended lane is reported at the c2-mechanical baseline.
• git grep -nE "H2-only in the legacy file|YAML alone never raises" -- plugins docs/conventions ":!*CHANGELOG.md" prints nothing.
• The PR body lists each of the sixteen keys with its new home and schema.
• scripts/check-changelog-fragments.sh --check-required origin/main exits 0.

Out of scope

• Dropping the legacy reads and deleting this repository's .claude/source-control.md (chore: drop the one-release .claude config reads and this repository's old config files #9737).
• Moving other repositories' keys (the host-run slice filed beside this one).

Posted by the issue-triage session. This was generated by AI.