Harden monitor-meta workflow baseline normalization and diffing

[Copilot]

The monitor-meta workflow was failing with exit code 5 after the deterministic-hash rewrite because it compared newly normalized output against a stale pre-normalization baseline and let brittle jq/shell behavior fail the job. This change keeps the workflow structure intact while making baseline handling, hashing, and diff generation deterministic and failure-tolerant.

• Workflow hardening

  • Adds shell: bash to every run: step
  • Starts each script with set -euo pipefail so failures surface at the actual command boundary instead of as an opaque step exit

• Deterministic baseline comparison

  • Writes trimmed-meta.json with stable key ordering via jq -S
  • Normalizes .meta.last.json with the same sort/shape transform before any section diffing
  • Falls back to {} when the stored baseline is missing or invalid, so comparisons stay well-defined

• Diff generation without fragile sub-jq failures

  • Replaces per-section added_count / removed_count jq length calls with single-pass value emission
  • Counts non-empty diff lines with grep -c ., avoiding the non-zero jq behavior that was bubbling into step failure under strict shell settings
  • Keeps existing issue body structure and changed-section reporting

• Baseline persistence behavior

  • Guards the first-baseline commit path with || echo "Nothing to commit" to avoid failing when no commit is needed
  • Preserves the existing first-run initialization and change-driven baseline update flow

• Expected next-run behavior

  • The committed .meta.last.hash was produced by the older pipeline, so the next scheduled or manual run should detect one change and rewrite .meta.last.json / .meta.last.hash into the normalized deterministic format
  • That self-heal is expected once and should not recur

- name: Compare for changes
  shell: bash
  run: |
    set -euo pipefail

    jq -S 'with_entries(.value |= (if type == "array" then sort else . end))' \
      .meta.last.json > normalized-old.json 2>/dev/null || echo '{}' > normalized-old.json

    CHANGED_SECTIONS=$(jq -r --slurpfile old normalized-old.json '
      to_entries
      | map(select(.value != ($old[0][.key] // [])) | .key)
      | join(",")
    ' trimmed-meta.json)