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feat(cross): Move embedder build to --prepare step - #195

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MEverett90 wants to merge 4 commits into
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me/prepare-embedder
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feat(cross): Move embedder build to --prepare step#195
MEverett90 wants to merge 4 commits into
mainfrom
me/prepare-embedder

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@MEverett90

@MEverett90 MEverett90 commented Sep 3, 2026

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Description

  • --prepare now builds the embedder, not just augments. Previously --prepare only built augment overlay libraries; --build would then rebuild them redundantly. Now --prepare calls a new _buildEmbedder method that runs both augments and the CMake/meson embedder build, returning an _EmbedderResult. When --prepare and --build are combined in one invocation, the result is passed directly to _build, skipping the second embedder build entirely.
  • Skip-if-built fast path for --build. When --build runs standalone (after a prior --prepare), it checks whether the source tree has changed and all backend binaries are present before re-running cmake/meson. The check uses a content-based SHA-256 fingerprint of the source tree written to .emb-source-stamp on a successful build, so edits, adds, deletes, and renames are all detected reliably — including across git checkout and on filesystems with coarse mtime granularity (HFS+, FAT32).

Type of Change

  • ✨ New feature (non-breaking change which adds functionality)
  • 🛠️ Bug fix (non-breaking change which fixes an issue)
  • ❌ Breaking change (fix or feature that would cause existing functionality to change)
  • 🧹 Code refactor
  • ✅ Build configuration change
  • 📝 Documentation
  • 🗑️ Chore

@MEverett90
feat(cross): _build() now accepts an optional preparedEmbedder parame…
9cf3950 
…ter. When --prepare --build are combined, the result from --prepare is passed through directly, skipping the second _buildEmbedder call entirely — no redundant augment rebuild.
@MEverett90
feat(cross): add source fingerprinting to skip-if-built check
ab4a8ca 
When --build falls back to _buildEmbedder(skipIfBuilt: true), check a
.emb-source-stamp file in the build root against a SHA256 fingerprint of
the embedder source tree (file paths + sizes + mtimes). If the stamp
matches and all backend binaries are present, the cmake/meson step is
skipped entirely; otherwise the build runs and a new stamp is written.

Without this, skipIfBuilt only checks for the presence of built
binaries — source edits between --prepare and --build would be silently
ignored because cmake is never invoked to notice them.
@MEverett90
fix(cross): use content-based fingerprint, fix doc comment and cleanup
1e36499 
Replace the mtime-based source fingerprint with SHA-256 content hashing
so that git checkout, cp -a, and coarse-granularity filesystems (HFS+,
FAT32) no longer produce false skip-if-built cache hits.

Also fixes the _EmbedderResult doc comment that was accidentally
concatenated with _StagedLibs's, removes a redundant .where(success)
filter after an exhaustive check, and normalizes path construction to
use p.join consistently.

Adds unit tests for sourceFingerprint covering determinism, content
change detection, file add/remove, hidden-dir exclusion, and
mtime-independence.
@MEverett90
MEverett90 requested a review from jwinarske September 3, 2026 20:52
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@jwinarske jwinarske Awaiting requested review from jwinarske

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