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Phase 32. License + dead-code + reproducibility expansion (audit-7)

FieldValue
MEPMEP-56 §Phases
StatusLANDED
Started2026-05-29 14:54 (GMT+7)
Landed2026-05-29 14:54 (GMT+7)
Tracking issue—
Tracking PR#22510 follow-up
Commit0a753708ad

Gate​

Audit-7 lands seven surface changes driven by a fresh sweep against MEP-56 §2 to §6:

  1. mochi-runtime.gemspec license: MIT → Apache-2.0. MEP-56 §1 and §4 declare mochi-runtime as Apache-2.0. The gemspec at line 6 declared MIT, contradicting both the spec and the emitted user-gem (build.go:246 hardcodes Apache-2.0, asserted by phase22_test.go:61). Installed mochi-runtime and a Mochi-emitted gem would have ended up under different licenses. Repo root LICENSE remains MIT (governs the rest of the repo); the runtime gem is the spec-carved Apache-2.0 exception. phase31_audit_6 surfaced this as a finding; audit-7 picks the side that matches the spec.

  2. TestPhase32Reproducibility expanded from 3 to 8 cases, covering all 7 build targets. Bundle, IRubyKernel, Tebako, TruffleNative, and MRuby targets share the same RubySource()+fmt.Sprintf emission path as Source/Gem but were not previously byte-equality-gated. A future regression introducing a timestamp into press.sh, a tmpdir leak in the IRuby notebook JSON, or a map-iter non-determinism in mruby_build.sh will now fail the gate. All 5 added cases pass byte-equal across two builds locally.

  3. findRuby errors when $MOCHI_RUBY is set but points to an inaccessible binary. Before, a typo or stale value silently fell through to Homebrew/PATH, masking the user's intent. With sub-phases 29.1/29.2/29.3 (JRuby/TruffleRuby/mruby) planned to pin specific interpreters via MOCHI_RUBY, a silent fall-through would route the runtime matrix back to CRuby and the regression would only surface as "tests look fine but the wrong runtime was tested". Now MOCHI_RUBY set + os.Stat failure returns MOCHI_RUBY points to %q which is not accessible: ....

  4. CI gains a gem install + require smoke probe. Previous workflow ran gem build and stopped there; a mochi-runtime.gemspec regression that dropped a required lib/mochi/runtime/*.rb file (e.g., from a wrong Dir["lib/**/*.rb"] glob) would still pass because unit tests ran against the source tree with -Ilib. Now CI installs the packed gem (gem install --no-document), cd / to escape the source tree, and requires each runtime sub-module. A regression in the gem's file list now fails CI with a LoadError.

  5. Dead Toolchain.Bundle, Driver.CacheDir, and effectiveCacheDir() culled. Toolchain.Bundle was set at build.go:77 from exec.LookPath("bundle") and never read. Driver.CacheDir was set by ~30 tests (&Driver{CacheDir: t.TempDir()}) and read only by effectiveCacheDir(), which was itself unreferenced. The cache-dir-as-tempdir test pattern was inherited from MEP-46 / MEP-47 boilerplate and is meaningless here. All 30+ test sites converted to plain &Driver{}.

  6. Dead MethodParam.Default (rtree) culled. Field was never set anywhere in lower or emit; the RubyString branch that consumed it was unreachable. Dropped both the field and the branch.

  7. Dead _ = strings.TrimSpace + strings import in phase18_test.go removed. Leftover unused-import suppressor from a prior refactor; strings was no longer used in that file.

Audit findings not auto-fixed​

Two findings from the audit-7 sweep are deferred to a future phase:

  1. Package-level mutable agentsByName in transpiler3/ruby/lower/lower.go:16. Each Lower() call writes a global map[string]*aotir.AgentDecl then reads it from lowerExpr. Two concurrent Driver.Build invocations would race. No other transpiler3 backend ships state this way, and the Ruby driver does not document concurrency one way or the other. The proper fix is to thread a lowerCtx struct through the 29 lower* functions, which is a non-trivial refactor and out of scope for an audit-pass. No current code path exercises concurrent builds (no t.Parallel(), no go func in driver), so this is a latent-only hazard.

  2. Mochi::Runtime::Stream MPMC behavior is single-threaded-only in tests. Spec §1 calls streams a "bounded MPMC broadcast channel". test_stream.rb exercises subscribe / subscribe_limit / late-subscriber-miss / multi-subscriber-broadcast but all from one thread. A multi-producer / multi-consumer test (Thread.new producers + consumers + pop) would catch a deadlock or lost message under contention. Out of scope here because it is additive coverage, not a known regression.

Build target / audit decisions​

Four decisions are baked into this phase:

  1. Pick the side that matches the spec when the divergence is documented there. MEP-56 §1 explicitly carves out the runtime as Apache-2.0; the gemspec is the surface that was wrong, not the spec. Phase 31 left the call open; phase 32 closes it spec-side.
  2. Test every target in the same harness rather than carve sub-tests by target type. The snapshotEmittedFiles walk is generic; adding 5 table rows is cheaper than maintaining 5 parallel tests and gives a uniform failure signal.
  3. CI smoke probe runs gem install, not just gem build. A gem can pack without being installable (missing dependency, wrong required ruby version, broken Dir[] glob). The probe catches the install + load case in addition to the pack case.
  4. MOCHI_RUBY is a hard pin, not a hint. When set, a missing binary is an error, not a "try elsewhere". The runtime matrix needs this guarantee.

Files changed​

FilePurpose
mochi-runtime/mochi-runtime.gemspecLicense MIT → Apache-2.0
transpiler3/ruby/build/build.goDropped Toolchain.Bundle, Driver.CacheDir, effectiveCacheDir(); findRuby errors on bad MOCHI_RUBY
transpiler3/ruby/build/phase32_reproducibility_test.goAdded 5 cases for Bundle, IRubyKernel, Tebako, TruffleNative, MRuby targets
transpiler3/ruby/build/phase*_test.go (30+ files)Converted &Driver{CacheDir: t.TempDir()} to &Driver{}
transpiler3/ruby/build/phase18_test.goDropped dead _ = strings.TrimSpace and strings import
transpiler3/ruby/rtree/nodes.goDropped dead MethodParam.Default field + RubyString branch
.github/workflows/transpiler3-ruby-test.ymlAdded gem install + require smoke probe step
website/docs/implementation/0056/index.mdPhase 32 row appended
website/docs/implementation/0056/phase-32-audit-7.mdThis tracking page

Test set​

  • TestPhase32Reproducibility now 8 subtests, all PASS:
    • hello_source, records_and_query, hello_gem (existing), plus hello_bundle, hello_iruby, hello_tebako, hello_truffle, hello_mruby.
  • Full go test -timeout 600s ./transpiler3/ruby/...: PASS (build 12.8s, rtree 0.5s).
  • mochi-runtime minitest suite: 21 runs / 42 assertions / 0 failures.
  • Local gem install --user-install + require smoke probe: PASS on CRuby 4.0.

Closeout notes​

Audit-7 is a small gap-closure pass driven by a fresh §1 to §6 read of MEP-56. The two scope-stretch findings (concurrency in lower/lower.go, MPMC stream test) are surfaced as known gaps; both would be appropriate as audit-8 or as standalone follow-up PRs. The license fix completes the audit-6 outstanding finding. The reproducibility expansion to 7 targets is the highest-leverage change: it closes the matrix coverage gap that phase 31 explicitly carved out as "low cost follow-up".