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| id | ticket | title | created | tags | |||||
|---|---|---|---|---|---|---|---|---|---|
| LSN-0014 | packer-docs-import | Pack wizard summary validation and pack execution legacy lesson | 2026-03-26 |
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Context
Legacy import from docs/packer/learn/pack-wizard-summary-validation-and-pack-execution.md.
This lesson preserves the packer-owned semantics behind the Studio-side pack wizard.
Key Decisions
Summary, validation, and pack execution are distinct packer-owned phases
What: summary is a fast snapshot-backed preflight view, validation is a blocking-diagnostics gate over the same active pack set, and packWorkspace(...) is the only artifact-emitting operation, rerunning the gate on a fresh frozen snapshot and promoting staged outputs only after coherent success.
Why: Studio-side shelling only works if packer provides one coherent operational story instead of a mix of stale UI assumptions and live filesystem rereads.
Trade-offs: This model is stricter and less forgiving than trusting previous UI state, but it prevents stale or torn assumptions from leaking into final build output.
Patterns and Algorithms
- Define the active pack set as
registered + included in build. - Keep summary fast and snapshot-backed.
- Let only blocking diagnostics fail first-wave validation.
- Re-run the gate on a fresh execution snapshot before emission.
- Stage outputs before promoting them to final
build/.
Pitfalls
- Treating summary as emitted-artifact preview.
- Validating a broader set than the active pack set.
- Letting warnings fail the first-wave gate.
- Reading live filesystem bytes after frozen execution starts.
Takeaways
- Green validation from a few seconds earlier is not enough; pack execution must revalidate on a fresh frozen snapshot.
- Packer-owned result semantics should be enough for Studio to render packing and result phases.
- Legacy source attribution:
docs/packer/learn/pack-wizard-summary-validation-and-pack-execution.md.