docs(AGENTS): fix reproducibility guidance (sandbox sets SOURCE_DATE_EPOCH) by bryan-minimal · Pull Request #266 · gominimal/pkgs

bryan-minimal · 2026-06-17T22:42:12Z

What

Corrects the Reproducibility (required) guidance added in #259, which had two factual errors and one framing issue that caused real fallout.

Why

The build sandbox already exports SOURCE_DATE_EPOCH=0 and PYTHONHASHSEED=0, and minimal-check's build script disallowed-patterns checker actively rejects re-setting them in a build.sh. But the merged guidance said the opposite:

It claimed "the sandbox does not pin the clock" — false.
It told authors to export SOURCE_DATE_EPOCH=0 (and PYTHONHASHSEED=0) — which fails CI.

This already bit us: the nspr reproducibility PR followed the guidance, added export SOURCE_DATE_EPOCH=0, and failed minimal-check. CodeRabbit also cited the guidance to (incorrectly) request the same export on an unrelated PR.

A secondary issue: the bullets read as a universal checklist, so the C/autotools items (e.g. libtool .la cleanup) got applied to non-C packages.

Changes

State that the sandbox provides SOURCE_DATE_EPOCH=0 / PYTHONHASHSEED=0 and must not be set in build.sh.
Replace the "export SOURCE_DATE_EPOCH=0" bullet with the correct pattern for builds that ignore SOURCE_DATE_EPOCH: pin the specific stamp (with nspr's SH_DATE/SH_NOW as the worked example).
Fold the libtool .la cleanup into the C/C++ bullet (where it belongs) and make explicit that authors apply only the bullet for their build system, not all of them.

🤖 Generated with Claude Code

Summary by CodeRabbit

Documentation

Updated build determinism and reproducibility guidance with clarified environment variable configuration in the build sandbox
Refined C/C++ build recipes with improved cleanup procedures for better reproducibility
Expanded recommendations for projects with embedded timestamps, including practical implementation examples

…_EPOCH The sandbox already exports SOURCE_DATE_EPOCH=0 and PYTHONHASHSEED=0, and minimal-check's disallowed-patterns checker rejects re-setting them. The guidance from #259 wrongly told authors to export them (and claimed the sandbox does not pin the clock), which made the nspr repro PR fail CI. - State the sandbox provides both; do not set them in build.sh. - Replace the bad export bullet with the correct pattern (pin the specific stamp; nspr SH_DATE/SH_NOW as the example). - Fold libtool .la cleanup into the C/C++ bullet; make explicit that authors apply only the bullet for their build system. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

coderabbitai · 2026-06-17T22:42:45Z

No actionable comments were generated in the recent review. 🎉

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Reviewing files that changed from the base of the PR and between 8144780 and 7c18e0b.

📒 Files selected for processing (1)

AGENTS.md

📝 Walkthrough

Walkthrough

Updates the "Reproducibility (required)" section of AGENTS.md to note that the build sandbox already exports SOURCE_DATE_EPOCH=0 and PYTHONHASHSEED=0 and that minimal-check rejects user-set duplicates. Folds *.la libtool archive removal into the C/C++ recipe and replaces the old embedded-timestamps bullet with wall-clock bake-in guidance including an nspr pinning example.

Changes

Determinism documentation update

Layer / File(s)	Summary
Sandbox env vars, build recipes, and embedded timestamp guidance `AGENTS.md`	Preface updated to document sandbox-exported `SOURCE_DATE_EPOCH=0`/`PYTHONHASHSEED=0` and `minimal-check` rejection of user re-setting. `*.la` removal added to the C/C++ autotools recipe. Old "Embedded timestamps" bullet removed; replaced with guidance for builds that bake wall-clock time despite `SOURCE_DATE_EPOCH`, with an `nspr` stamp-variable pinning example.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Possibly related PRs

gominimal/pkgs#259: Directly overlaps — also a documentation-only edit to AGENTS.md's determinism guidance covering the same SOURCE_DATE_EPOCH/PYTHONHASHSEED embedded-timestamps and C/C++ libtool .la cleanup recipe details.

Suggested reviewers

msample
norrietaylor

Poem

🐇 A sandbox already knows the time is zero,
No need to set what's set — the build's the hero!
Libtool archives? Delete them with glee,
And nspr stamps pinned for reproducibility.
The rabbit hops on, deterministic and free! 🏗️

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: correcting reproducibility guidance documentation by clarifying that the sandbox already sets SOURCE_DATE_EPOCH.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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 bryan/agents-repro-wording

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edge-delta

Good fix — the old guidance was actively causing CI failures and confusing both humans and bots. The factual corrections and the "only apply your bullet" framing are solid improvements.\n\nLeft two minor nits on the nspr example bullet (clarity, not correctness). Neither is a blocker.

edge-delta · 2026-06-17T22:50:23Z

+- **A build that bakes in its own wall-clock time** despite `SOURCE_DATE_EPOCH` (version
+  strings, generated headers): pin that specific stamp rather than re-exporting
+  `SOURCE_DATE_EPOCH`. For example `nspr` overrides the make variables its version header
+  is generated from (`SH_DATE` from `$SOURCE_DATE_EPOCH`, `SH_NOW=` to omit the build time).


Nit: The other bullets show the exact flags/exports to paste into build.sh, but this one describes the strategy without a concrete snippet. A one-liner example (even pseudo-code) would make it as copy-pasteable as the rest:

# nspr example: derive SH_DATE from the sandbox-provided epoch; suppress SH_NOW make SH_DATE="$(date -u -d @$SOURCE_DATE_EPOCH '+%Y-%m-%d %T')" SH_NOW= ...

Optional — the prose is accurate as-is, but the worked example would lower the bar for new contributors.

edge-delta · 2026-06-17T22:50:24Z

+- **A build that bakes in its own wall-clock time** despite `SOURCE_DATE_EPOCH` (version
+  strings, generated headers): pin that specific stamp rather than re-exporting
+  `SOURCE_DATE_EPOCH`. For example `nspr` overrides the make variables its version header
+  is generated from (`SH_DATE` from `$SOURCE_DATE_EPOCH`, `SH_NOW=` to omit the build time).


Ultra-nit: `SH_NOW=` reads as if the value was accidentally omitted. Consider `SH_NOW=""` (or `SH_NOW=` (empty)) to make it visually explicit that the empty string is intentional, not a typo. Readers unfamiliar with nspr's Makefile may stumble here.

bryan-minimal mentioned this pull request Jun 17, 2026

agent-browser: make Rust CLI + pnpm tree reproducible #264

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edge-delta Bot reviewed Jun 17, 2026

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edge-delta Bot mentioned this pull request Jun 17, 2026

haskell-language-server: add reproducibility flags to build.sh #267

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twitchyliquid64 approved these changes Jun 18, 2026

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bryan-minimal added this pull request to the merge queue Jun 18, 2026

Merged via the queue into main with commit b265510 Jun 18, 2026
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bryan-minimal deleted the bryan/agents-repro-wording branch June 18, 2026 17:33

coderabbitai Bot mentioned this pull request Jun 29, 2026

perl: complete reproducibility — pin all host/time-derived Config fields #291

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docs(AGENTS): fix reproducibility guidance (sandbox sets SOURCE_DATE_EPOCH) - #266

docs(AGENTS): fix reproducibility guidance (sandbox sets SOURCE_DATE_EPOCH)#266
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bryan-minimal commented Jun 17, 2026 •

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