The 2026-05-08 attempt-2 dogfood batch had 8/8 tasks "succeed" with
zero branches pushed. Root cause: my AR-21 diff-verification block was
running under set -euo pipefail without explicit error handling. A
single non-zero exit anywhere in the `git diff | tr | sed` pipeline
killed finalize.sh before the metadata write or push ran.
Specific risk: `git diff <REF_HEAD>..HEAD` returns non-zero when the
SHA is unreachable (e.g., shallow clone with init.sh fork-fallback
where upstream-ref wasn't fetched). pipefail then kills the pipeline,
set -e kills the script.
Fix: wrap the entire AR-21 block in `set +eo pipefail` (with explicit
`set -eo pipefail` restore at the end). Also:
- Use `${arr[@]:-}` instead of `${arr[@]}` for set -u safety on empty
arrays
- Add `|| true` to git command substitutions (belt-and-braces)
- Use `printf` instead of `echo` for the comma-wrap (more portable)
Verified locally: when `/workspace/reference/main/.git` is absent the
block correctly skips with the existing fallback; when present and
upstream-ref is reachable, the block runs and reports DIFF_VERIFIED.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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