Extract CSMA library to scripts/lib/ to eliminate duplication

[fullsend-ai-retro]

What happened

In PR #35, the CSMA rate-limit resilience library (~300 lines) was inlined into scripts/post-prioritize.sh (lines 15–332). The same library was also inlined into scripts/post-prioritize-test.sh (lines 269–586) for unit testing. The comment # --- Inlined from lib/github-api-csma.sh --- indicates this code originally lived in a shared lib/ directory, but no such directory exists in the repo today.

What could go better

The library is now copy-pasted in two files (script and test), totaling ~600 duplicated lines. Any bug fix, new retry pattern, or behavioral change to the CSMA logic requires updating both copies in lockstep. If additional scripts adopt CSMA (see related proposal), the duplication would compound further. The risk is moderate — the library is stable by nature (retry logic rarely changes) — but the current pattern also forces the test file to inline the library separately rather than testing the canonical copy, which weakens the test's coverage guarantee. Confidence: medium-high. The duplication is factual; the maintenance risk is a judgment call informed by the codebase's growth trajectory.

Proposed change

Create scripts/lib/github-api-csma.sh containing the canonical CSMA library. Update post-prioritize.sh to source "${SCRIPT_DIR}/lib/github-api-csma.sh" instead of inlining. The test file should also source the canonical copy for its unit tests, ensuring it tests the actual production code. The post-scripts run on the GitHub Actions runner (not in the sandbox), so source is reliable. The include-guard (GITHUB_API_CSMA_SH_LOADED) already exists in the inlined code, so multiple source calls are safe.

Validation criteria

After extraction: (1) scripts/lib/github-api-csma.sh exists as a single file. (2) post-prioritize.sh no longer contains the inlined CSMA block — it sources the lib. (3) post-prioritize-test.sh sources the same lib and all 6 existing tests (happy-path, rate-limit-retry, auth-error, exhausted-retries, exit0-rate-limit-retry, exit0-rate-limit-exhausted) continue to pass. (4) No other file in the repo contains a duplicate copy of the CSMA functions.

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Generated by retro agent from #35

[fullsend-ai-triage]

🤖 Finished Triage · ✅ Success · Started 6:00 PM UTC · Completed 6:04 PM UTC
Commit: e8381e3 · View workflow run →

[fullsend-ai-triage]

Triage Summary

Severity: low · Category: refactoring

Problem

The CSMA rate-limit resilience library (~300 lines) is duplicated in post-prioritize.sh (lines 15–332) and post-prioritize-test.sh (lines 269–586). Both copies are confirmed present in the current codebase. The scripts/lib/ directory does not yet exist.

Root Cause

PR #35 inlined the library rather than extracting it to a shared location. The inline comment references lib/github-api-csma.sh as the intended canonical path.

Recommended Fix

1. Create scripts/lib/github-api-csma.sh with the canonical CSMA library
2. Replace the inlined block in post-prioritize.sh with source "${SCRIPT_DIR}/lib/github-api-csma.sh"
3. Update post-prioritize-test.sh to source the same canonical copy
4. Verify all 6 existing CSMA tests pass against the extracted lib

The existing include guard (GITHUB_API_CSMA_SH_LOADED) already supports safe multiple sourcing.

Proposed Test

# After extraction, run existing test suite:
bash scripts/post-prioritize-test.sh

# Verify no CSMA function definitions remain in post-prioritize.sh:
grep -c 'github_csma_run()' scripts/post-prioritize.sh  # expect 0
grep -c 'github_csma_run()' scripts/lib/github-api-csma.sh  # expect 1

# Verify no duplicate copies exist:
grep -rl 'GITHUB_API_CSMA_SH_LOADED' scripts/ | wc -l  # expect 1 (lib only)

Notes

• Issue Add CSMA rate-limit protection to post-retro.sh API calls #71 (adding CSMA to post-retro.sh) depends on this extraction landing first
• PR feat(harness): report categorized post-script failures on issue/PR #38 already establishes the scripts/lib/ shared library pattern with post-failure-report.sh
• This is a straightforward refactoring with clear validation criteria provided in the issue

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Labels: This is a well-specified refactoring task ready for implementation. Applying ready-to-code and enhancement labels, removing the triage intake label.