47 lines
2.1 KiB
Markdown
47 lines
2.1 KiB
Markdown
---
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id: LSN-0011
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ticket: packer-docs-import
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title: Foundations workspace runtime and build legacy lesson
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created: 2026-03-26
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tags:
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- packer
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- legacy-import
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- foundations
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- deterministic-build
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---
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## Context
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Legacy import from `docs/packer/learn/foundations-workspace-runtime-and-build.md`.
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This lesson preserves the stable foundation for workspace control, runtime snapshots, writes, and deterministic build output.
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## Key Decisions
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### The stable foundation is filesystem-first authoring plus coherent snapshot-backed runtime and deterministic build
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**What:** The packer keeps the workspace open and filesystem-first, anchors managed identity in registry and asset declarations, serves reads through coherent runtime snapshots, coordinates writes through packer-owned lanes, and emits deterministic build outputs from validated state.
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**Why:** The original implementation wave spread this knowledge across many PR slices, which stopped being a good onboarding surface. The stable model needed one didactic consolidation.
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**Trade-offs:** This architecture demands stronger ownership of snapshots, write coordination, and deterministic ordering, but it prevents UI heuristics, traversal order, or cache state from silently becoming semantic authority.
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## Patterns and Algorithms
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- Keep `asset_id` stable and separate from `asset_name`.
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- Treat `asset.json` as authoring intent rather than registry bookkeeping.
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- Read from coherent runtime snapshots.
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- Serialize commit-bearing writes through one project-scoped semantic lane.
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- Order build outputs deterministically by managed identity.
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## Pitfalls
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- Treating `asset_name` as stable runtime identity.
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- Moving registry-owned fields into `asset.json`.
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- Depending on traversal order or UI order for build layout.
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- Treating cache state as semantic authority.
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## Takeaways
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- The packer foundation is as much about ownership and determinism as it is about file formats.
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- Filesystem durability, snapshot coherence, and deterministic emission must stay aligned.
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- Legacy source attribution: `docs/packer/learn/foundations-workspace-runtime-and-build.md`.
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