chore(build): make turbo's typecheck inputs self-verifying, and lock two runtime assumptions into tsc

[JSONbored]

The find

turbo.json's //#typecheck inputs is a hand-maintained approximation of tsc's real transitive surface, and its own comment admits the hazard:

"a snapshot of test/'s real cross-package reach as of the audit that added it, not a structural guarantee — a future test file importing from a NOT-yet-listed package/app would reopen the same silent-stale-cache gap." … "Re-run the same grep … before trusting this list again."

Nobody re-runs a grep on request. It had already drifted — four statically-imported paths were unhashed:

unhashed path	imported by
packages/loopover-mcp/lib/**	mcp-cli-error, mcp-gateway tests
packages/loopover-mcp/bin/**	mcp-cli-completion-spec (imports CLI_COMMAND_SPEC)
packages/loopover-miner/scripts/**	miner-benchmark, miner-env-reference tests
packages/discovery-index/scripts/**	validate-posthog-release test

Editing any of them could leave a stale cache HIT on a typecheck a real tsc --noEmit would fail — precisely the #5082 class this list exists to prevent.

The bin/** case is worse than an omission: it falsifies the comment's own stated reason for excluding it ("every test reference to it is a runtime path string … never a static import"). That was true when written; a later test made it false, and nothing noticed. Comment corrected rather than left misleading.

The fix

scripts/check-turbo-typecheck-inputs.ts — run that grep every CI instead of remembering it. This is the maintainability point directly: a computed list rather than a remembered one.

Two precision details that matter:

• dependsOn counts as coverage. @loopover/engine#build means turbo already hashes the engine's inputs, so engine/contract sources aren't false-positived. A checker that cried wolf here would be ignored within a week.
• Paths must exist on disk. The checker-testing files embed import statements inside fixture strings naming packages/engine/..., a workspace renamed away. A naive scan reported those as real reach — a false positive whose "fix" would have been hashing a directory that doesn't exist.

Also: two free tsc flags

isolatedModules and verbatimModuleSyntax, both measured at zero errors today. They turn assumptions the runtime already makes into compile-time guarantees: per-file transpilability (what --experimental-strip-types and esbuild already require) and type-only imports that can never be silently elided from — or dragged into — the self-host bundle that must have zero cloudflare:* imports.

Deliberately not enabling noImplicitReturns despite it costing only 3 errors: two are documented, intentional implicit-undefined switch arms ("Every other case implicitly returns undefined"). Churn against deliberate code for marginal value.

Verification

Guard mutation-tested via 8 unit cases (drift reported, dependsOn coverage, glob-narrower-than-reach, fixture-string exclusion, plus an invariant asserting this repo's own turbo.json stays covered so a turbo.json edit fails the suite too). turbo run typecheck --dry still resolves the graph. Full suite 25,332 passed; tsc, dead-source-files, import-specifiers green.

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	loopover-ui	b69fa14	Commit Preview URL Branch Preview URL	Jul 29 2026, 03:16 PM

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Important

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⏳ LoopOver is waiting…

LoopOver has seen this pull request and is waiting on CI checks to finish before reviewing it. This comment will update once the review runs.

_{🟩 Safe / merged · 🟦 Advisory · 🟨 Held for review · 🟥 Blocked / closed · 🟨 Waiting}

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.65%. Comparing base (a65655c) to head (b69fa14).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9853      +/-   ##
==========================================
- Coverage   91.74%   91.65%   -0.09%     
==========================================
  Files         917      917              
  Lines      112894   112840      -54     
  Branches    27153    27131      -22     
==========================================
- Hits       103576   103429     -147     
- Misses       8034     8125      +91     
- Partials     1284     1286       +2     

Flag	Coverage Δ
backend	95.68% <ø> (ø)

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see 1 file with indirect coverage changes

[codecov]

Bundle Report

Bundle size has no change ✅