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Phase 8. Build orchestration

FieldValue
MEPMEP-72 §Phases
StatusNOT STARTED
Tracking issue(pending)
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Commit(pending)

Gate​

TestPhase8Build in package3/typescript/build/phase08_test.go: subtests synth_workspace, materialise_node_modules, materialise_jsr_cache, invoke_node, invoke_deno, invoke_bun, invoke_browser_bundle, cache_reuse, golden_corpus. The first synthesises a workspace from a representative lockfile and asserts the rendered package.json + import-map.json + tsconfig.json match goldens. The next two materialise the dependency trees from the local cache (no network) and assert the file layout. The next four invoke the four runtime targets against a "hello world that calls zod" fixture and assert stdout matches the golden. The eighth asserts that a second build with no lockfile change reuses the cached workspace + dependency tree (no re-extraction). The ninth runs against all 24 fixture-corpus packages.

Lowering decisions​

The build orchestration combines four steps:

  1. Synthesise the workspace (re-uses phase 0's renderer): from the lockfile's [[npm-package]] and [[jsr-package]] tables, build the package.json dependencies map and the import-map.json imports map. The workspace root is target/ts/<runtime>/.

  2. Materialise the dependency tree: for each [[npm-package]], copy the unpacked tarball from $XDG_CACHE_HOME/mochi/ts-deps/npm/<pkg>@<version>/ into target/ts/<runtime>/node_modules/<pkg>/. For each [[jsr-package]], copy from $XDG_CACHE_HOME/mochi/ts-deps/jsr/@<scope>/<pkg>@<version>/ into target/ts/<runtime>/jsr_cache/@<scope>/<pkg>@<version>/. The copy is a content-addressed link (hard-link on POSIX, copy-on-write on macOS APFS, full copy on Windows) so multiple workspaces share the underlying tree.

  3. Invoke the host runtime / bundler: depending on runtime:

    • node22: node --enable-source-maps dist/index.mjs for run; tsc --noEmit for type-check.
    • deno2: deno run --allow-net --allow-read dist/index.ts for run; deno check dist/index.ts for type-check.
    • bun1.1: bun run dist/index.ts for run; bun build --target=node dist/index.ts for build.
    • browser: bun build --target=browser dist/browser/index.ts --outfile=dist/bundle/index.js (primary); esbuild --bundle --format=esm --target=es2024 --platform=browser (fallback).
    • edge: same as browser but with --define=process.env.NODE_ENV=production and the edge-runtime capability gate (phase 17).

  4. Link the emit output: the MEP-52 phase 12 emitter writes the Mochi-emitted TS source under target/ts/<runtime>/src/; the build orchestration links the shim files from target/ts_shims/ so the emitted TS can import them. The link layout matches what the user's source expressed via import ts "..." as <alias>.

The orchestration uses Go's os/exec with stdout / stderr capture; failures produce a clear diagnostic naming the failing step + the failed command's stderr.

The build cache is keyed on (workspace-manifest-hash, dep-tree-hash, runtime, target). A cache hit skips synthesis and materialisation; a cache miss re-runs the full pipeline. The cache directory is $XDG_CACHE_HOME/mochi/ts-build/<hash>/.

Files changed​

FilePurpose
package3/typescript/build/orchestrate.goOrchestrator, BuildOptions, Build
package3/typescript/build/materialise.gocontent-addressed link / copy from the cache to the workspace
package3/typescript/build/invoke.goper-runtime exec wrapper
package3/typescript/build/cache.goworkspace + dep-tree hash cache
package3/typescript/build/phase08_test.goTestPhase8Build sentinel
package3/typescript/build/testdata/hello_zod/*end-to-end fixture

Test set​

9 subtests as listed in the Gate section.

Cross-references​