Extract a shared pnpm install contract factory (core and contrib hand-write the same object)

Problem

pnpm-install-contract.json.genie.ts is hand-written independently in two repos, with structurally identical bodies:

• livestorejs/livestore → pnpm-install-contract.json.genie.ts (~89 lines)
• livestorejs/livestore-contrib → pnpm-install-contract.json.genie.ts (~64 lines)

Both build the same shape in the same field order: contract, packageManager, storeContract, dependencyGraphContract, installPolicy (the same 11 keys), workspaceManifestContract, and dependencyMaterializationProfile.identityInputs (the same 5 entries). The only genuine difference is the contract name string.

effect-utils today exports only the storage portion — pnpmInstallStorageContractV2 (genie/external.ts) — so each consumer hand-writes the surrounding object.

Why it matters

The drift has already started: contrib's copy omits core's metadata block and its supportedTraits / nativeBuildPolicyInputs / buck2Boundary extensions, with no comment recording whether that is deliberate. A reader cannot tell intent from divergence.

Because identityInputs drives install-drift classification, a field silently present in one repo and absent in the other means the two repos classify install drift differently — which is exactly the kind of divergence the shared pnpm task module exists to prevent.

Proposed

Export a factory alongside the existing storage helper:

buildPnpmInstallContract({
  contract,          // 'livestore/pnpm-install-contract' | 'livestore-contrib/…'
  workspaceData,     // the generated pnpm-workspace.yaml data
  packageManager,    // parsed from the root manifest
  extra?,            // repo-specific additions (core's metadata, buck2Boundary, …)
})

Both repos then call it, and repo-specific fields become an explicit, visible extra rather than an unexplained omission.

Notes

Found during a redundancy review of livestorejs/livestore-contrib#40. Not fixable from contrib alone: contrib composes effect-utils at a pinned revision, so this needs to land here first, then reach consumers via a pin bump.

Start in genie/external.ts, then compare the pnpm-install-contract.json.genie.ts files in livestore and livestore-contrib to identify the shared object shape and repo-specific additions. Add and export the proposed factory, then update both consumers to use it. Done means the shared fields are produced consistently and differences are explicit through extra.