fix: make package archives deterministic

[sabraman]

Summary

Makes SDK-built package archives deterministic by writing stable zip timestamps and file attributes. This keeps package SHA-256 values stable when the same package contents are rebuilt.

Validation

• Built Dark Mode twice into separate temporary directories
• Confirmed both archive SHA-256 values match
• Validated all example manifests with the publish profile

Summary by CodeRabbit

• Chores
  • Updated package build process to generate archives with deterministic and consistent metadata timestamps and file attributes.

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

tools/build_package.py now uses the stat module and a ZIP_EPOCH constant to ensure deterministic zip archive metadata. File writing switches from archive.write() to manually constructing ZipInfo objects with fixed timestamps, ZIP_DEFLATED compression, and permissions extracted from source file modes.

Changes

Deterministic Zip Package Metadata

Layer / File(s)	Summary
Archive configuration with deterministic timestamp tools/build_package.py	stat module imported and ZIP_EPOCH constant defined to standardize archive entry timestamps.
Deterministic archive entry writing tools/build_package.py	Archive entry creation replaces archive.write(path, rel) with ZipInfo construction that explicitly sets ZIP_EPOCH timestamp, ZIP_DEFLATED compression, and external_attr from source file permissions before writing via writestr().

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 A timestamp trapped in time so true,
No more chaos when zip files renew.
Fixed epochs and deflated care—
Build. Rebuild. Results compare!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix: make package archives deterministic' directly and concisely describes the main change: ensuring that package archives have stable, reproducible properties across rebuilds.
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 docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/deterministic-archives

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