Fast-forward autoloop/* branches when ahead=0 instead of merging

[Copilot]

The unconditional git merge origin/main in Step 3 (and in the companion sync-branches workflow) produced noisy "Merge main into branch" commits whenever a long-running branch had no unique commits. Those merge commits re-exposed every historical file as a patch touch, aggregating to >100 file changes on the next iteration's PR and tripping gh-aw's hard-coded E003 limit.

Changes

• workflows/autoloop.md — Replaced the Step 3 prose (and its content-delta git diff heuristic + bare git reset --hard) with an explicit four-case decision tree keyed on git rev-list --count ahead/behind:

  ahead	behind	Action
  0	0	checkout, no-op
  0	>0	fast-forward + push --force-with-lease
  >0	0	checkout, no-op
  >0	>0	checkout + merge

• workflows/sync-branches.md (Node.js template) and .github/workflows/sync-branches.md (deployed Python copy) — Same four-case logic in the per-branch sync loop, so the companion workflow cannot re-introduce the noisy merge commits the per-iteration step now avoids.

• .github/workflows/sync-branches.lock.yml — Regenerated via gh aw compile, with the two pre-existing manual fixups re-applied (permissions: contents: write; merge step ordered after Configure Git credentials).

--force-with-lease (not --force) so a concurrent push to the branch is rejected rather than clobbered. The fast-forward is lossless because ahead=0 proves every commit on the branch is already reachable from main.

ahead=$(git rev-list --count origin/main..origin/autoloop/{program-name})
behind=$(git rev-list --count origin/autoloop/{program-name}..origin/main)

if [ "$ahead" = "0" ] && [ "$behind" != "0" ]; then
  git checkout -B autoloop/{program-name} origin/main
  git push --force-with-lease origin autoloop/{program-name}
elif [ "$ahead" != "0" ] && [ "$behind" != "0" ]; then
  git checkout -B autoloop/{program-name} origin/autoloop/{program-name}
  git merge origin/main --no-edit -m "Merge main into autoloop/{program-name}"
else
  git checkout -B autoloop/{program-name} origin/autoloop/{program-name}
fi

[mrjf]

@copilot fix tests

[Copilot]

@copilot fix tests

Fixed in a7c81f5. The CI failure was ModuleNotFoundError: No module named 'yaml' in test_lock_creds_before_merge — .github/workflows/tests.yml only installs pytest, not pyyaml. Replaced the yaml.safe_load call with stdlib regex parsing (scoped to the agent: job body) so the test has no extra dependencies. All 100 tests pass locally.