Discord notify pipe buffer: what to review

Field	Value
Branch	feat/admin-and-merchant-portals, draft PR #976: feat(admin): portal navigation, financials and monitoring, plus the agent-process work behind them, not merged
Project	README.md
Issues	#956: bug(ci): Discord notification dies on any squash merge whose commit message exceeds the pipe buffer and #966: bug(ci): the #956 pipe-buffer SIGPIPE shape also lives in ai-changelog.yml and a discord-notify.yml fallback branch
Servers you need	None. There is nothing to click. This is two GitHub Actions workflows
Local origins	Not applicable

Is there anything to look at?

Two files, and one real-world proof you will get for free when this branch merges.

• The files are .github/workflows/discord-notify.yml and .github/workflows/ai-changelog.yml.
• The proof: this branch's squash-merge commit message will be enormous, 200-plus commits concatenated. That is exactly the payload that killed the notification last time. If Discord posts on merge, the fix held.
• The bug that produced this project was a 94,631-byte, 1,978-line squash-merge commit message.

What changed here?

head does not wait for a large writer once it has what it wants.

• Its early exit sends the writer SIGPIPE, the step runs under set -Eeuo pipefail, and that SIGPIPE takes the whole step down with no output at all.
• Symptom in CI: died in 0.2s, no error output.

The fix removes the pipe rather than raising the limit.

• printf ... | head -n 1 became bash parameter expansion, which takes everything before the first newline with no subshell and no second process.
• jq ... | head -n 50 became jq's own limit(50; ...), which caps the generator inside the process instead of asking head to discard the rest on the far side of a pipe.
• Three lines in discord-notify.yml had the identical shape. All three were fixed, not just the one the crash report pointed at.

The two follow-up instances turned out to fail in DIFFERENT ways, and only one matched the prediction.

• discord-notify.yml's fallback branch is a plain assignment, so a SIGPIPEd printf fails the whole step. Matches exactly.
• ai-changelog.yml's instance sits inside an if condition, and bash's errexit does not fire on a command whose status is being tested. So the step survived, every time.
• That difference uncovered a worse, silent bug the "does it crash" framing would have missed. pipefail reports the rightmost non-zero exit, so when printf dies (141) and grep -q legitimately matches (0), the pipeline still reports 141 and the if reads false even though the skip tag really was on line 1. A false negative with no error and no visible symptom.
• The same fix eliminates it, because there is no longer a second process to race against.

What is deliberately NOT done?

Two more genuinely exposed instances were found and filed rather than fixed here.

• #968: bug(ci): the #956/#966 pipe-buffer SIGPIPE shape also lives in ai-changelog.yml's PR-body head -c 500 lines, the "Generate changelog with AI" step, which pipes a PR body through head -c 500 inside a plain assignment. GitHub allows PR bodies up to 65,536 characters. Open.

A third candidate was deliberately left out of that issue.

• Its grep -oE stage narrows output to a handful of short matching lines before head -1 ever sees it, regardless of how large the upstream data is, so it is not meaningfully exposed.
• Same reasoning for structurally identical pairs in issue-triage.yml and assign-milestone.yml.

What open findings touch this project?

• Nothing from ../merchant-and-venue-dashboards/branch-review-0828.md. The reviewer checked the three workflow quoting fixes and listed them under what was found clean.
• One thing worth knowing for the merge itself: the em dash count on discord-notify.yml is 2 before and 2 after, both pre-existing and outside the touched lines. Neither was added by this fix.

What issue does each piece close?

Piece	Issue	State
The original three-line fix	#956: bug(ci): Discord notification dies on any squash merge whose commit message exceeds the pipe buffer	Fixed on branch, proven against the real 94,631-byte message
The two follow-up instances	#966: bug(ci): the #956 pipe-buffer SIGPIPE shape also lives in ai-changelog.yml and a discord-notify.yml fallback branch	Fixed on branch
The two remaining instances	#968: bug(ci): the #956/#966 pipe-buffer SIGPIPE shape also lives in ai-changelog.yml's PR-body head -c 500 lines	Open, filed not fixed
The subject-only skip rule this fix preserves	#348: ai-changelog + discord-notify: skip-logic refinements (subject-only matching, empty-AI guard)	Closed, behaviour verified unchanged