fix(sdlc): harden authority-case-check.yml against grep|head SIGPIPE on long PR bodies

[ryanklee]

AuthorityCase: CASE-SDLC-REFORM-001
cc-task: reform-fix-authority-case-check-sigpipe-20260601

What

The authority-case-check.yml "Parse AuthorityCase reference from PR body" step extracted ids with grep -oiE 'PATTERN' | head -1 under set -euo pipefail. When grep's -o output exceeds its ~4 KiB stdio buffer it flushes in pieces; head -1 closes the pipe after the first line, so grep's next write takes SIGPIPE -> exit 141 -> pipefail + set -e -> the step exits 1. This deterministically red-blocked any methodology PR whose body carried enough CASE-/cc-task matches (this is what blocked hapax-dev #3834).

Fix

The three extraction pipes now use grep -m1 -oiE ... <<<"$PR_BODY" || true plus a first-match parameter-expansion trim:

• grep -m1 stops after the first matching line, so grep never keeps writing into a pipe a downstream stage closed early -- no SIGPIPE.
• || true keeps a no-match from tripping set -e, retiring the redundant echo | grep -q guards (themselves a latent echo-pipe SIGPIPE on >64 KiB bodies).
• the trim keeps only the first match when -o emits several on one line, preserving the old head -1 semantics and keeping a multi-line value out of $GITHUB_OUTPUT.

set -euo pipefail is retained.

Test

tests/test_authority_case_check_sigpipe.py lifts the real run block from the workflow YAML and executes it against crafted bodies. The many-match body exits 141 pre-fix and 0 post-fix; the >2 KiB single-ref body parses cleanly; same-line multi-match yields a single newline-free id. uv run pytest tests/test_authority_case_check_sigpipe.py -> 6 passed.

This PR's own AuthorityCase Check runs the patched workflow from the PR head, proving the fix end-to-end.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Improved stability of metadata extraction from pull requests, preventing failures when processing long or complex pull request bodies.

• Tests

  • Added regression tests covering multiple parsing scenarios and edge cases to ensure consistent, reliable metadata parsing.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: d4d3e0b4-827a-4e68-9267-02332f3bbcd9

📥 Commits

Reviewing files that changed from the base of the PR and between 08170f5 and 1b62404.

📒 Files selected for processing (1)

• .github/workflows/authority-case-check.yml

🚧 Files skipped from review as they are similar to previous changes (1)

• .github/workflows/authority-case-check.yml

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📝 Walkthrough

Walkthrough

The workflow step parsing AuthorityCase metadata from PR bodies is rewritten to avoid SIGPIPE failures using here-strings and parameter expansion instead of piped grep/head operations. A regression test module is added that executes the actual parse step against crafted PR bodies to validate extraction across edge cases.

Changes

AuthorityCase metadata parsing robustness

Layer / File(s)	Summary
Workflow SIGPIPE-safe parsing .github/workflows/authority-case-check.yml	Replaced grep pipe chains with grep here-strings (<<<"$PR_BODY"), sed, and parameter expansion (${var%%$'\n'*}) to extract case_id, slice_id, cc_task, and pre_methodology. Added `
Regression test module: infrastructure and scenarios tests/test_authority_case_check_sigpipe.py	New pytest module that locates the workflow file, extracts the id: parse step run script, and executes it in subprocesses with crafted PR_BODY and GITHUB_OUTPUT. Includes tests for long bodies, many matches, same-line multi-matches, no references, slice/pre-methodology detection, and legacy cc-task-only parsing; asserts exit code 0, key=value output format, and expected identifiers.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 I nibbled bytes of long PR prose,
I pushed them through grep where the wild wind blows,
No SIGPIPE snapped, no head did fall,
Outputs tidy, one key=value for all,
Hop, test, repeat — the pipeline's whole.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description includes a structured explanation of the problem, fix, and test plan, but is missing required AuthorityCase template fields (Case and Slice) and CLAUDE.md hygiene checklist.	Add required template sections: populate 'Case:' with 'CASE-SDLC-REFORM-001' and 'Slice:' with the appropriate value, and complete the CLAUDE.md hygiene checklist by checking applicable boxes.
Docstring Coverage	⚠️ Warning	Docstring coverage is 66.67% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and specifically describes the main change: hardening the authority-case-check.yml workflow against a SIGPIPE failure caused by grep piped to head on long PR bodies.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch epsilon/reform-fix-authority-case-check-sigpipe-20260601

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