Project target cache v1

Status: implemented scalar Web, pathless C11 and pathless npm cache lanes; HOSTED GREEN under the v0.4.0 release baseline. Target execution and measured performance are not implied.

Audience: compiler contributors and embedding hosts that already hold an admitted immutable Project revision.

ProjectTargetCache is a caller-owned cache with one exact entry for the existing scalar Web inline carrier and one for the existing pathless native-C11 carrier plus one for the existing pathless npm carrier. It accepts only a private-constructor ProjectRevision; source verification, HIR validation, workspace linking and Project-profile admission therefore precede the cache boundary. Every request also invokes the revision's held-input check. The cache grants no source, filesystem, process, execution, or publication authority.

Exact key and replay

Each key binds compiler package/version and either semaprax.project-scalar-web-target-work.v1 or semaprax.project-native-c11-target-work.v1 or semaprax.project-pathless-npm-target-work.v1, canonical manifest bytes, Project revision, workspace revision, Project graph digest, entry module, ordered Web exports, and the requested target byte limit. A mismatch is a miss rather than an approximate hit.

On a miss, the ordinary Web, C or npm path emits the selected target. On an exact hit, the cache skips only deterministic target emission and carrier assembly. The Web lane reruns its independent integrity verification. The C lane replays canonical payload digest, exact revision/manifest/source/export bindings, artifact hex/count/SHA inventory and every embedded C-header envelope, then compares separately retained digest and byte facts. The npm lane invokes ProjectNpmBuild::verify to replay its closed schema, semantic recipe and exact ordered file bytes/digests, then matches the manifest/package and source-bound cache key plus separately retained digest and byte facts. A failed miss or replay does not replace the prior successful entry, and a miss in one lane does not evict another.

The cache does not deserialize untrusted target bytes or persist an entry. Compiler executable identity is not claimed; same-process ownership and the closed compatibility keys bound these lanes. C compilation, linking and execution are absent. Package-manager installation and npm runtime execution are absent. Wasm-package, non-scalar, cross-revision, cross-process, and partial target-work reuse remain open.

Work report

Each result carries canonical semaprax.project-target-cache-work.v1 JSON. It records the exact target key, whether target emission was reused, zero or one emitter call, one carrier replay call, retained payload digest and artifact bytes. Validation fields distinguish the admission completed before revision construction from the exact target subject replay performed on this request. The report is bounded to 32 KiB and makes no allocator, RSS, elapsed-time, execution, or authority claim.

Module-local authored regressions cover Web cold/exact/incompatible behavior; C cold/exact replay, lane isolation and max-byte key drift; and fail-closed C carrier tampering with recovery after restoring the exact entry. npm adds exact hit, C/npm lane isolation, limit drift and altered-cache-fact rejection/recovery. The implemented cases have hosted-green release evidence. Before any performance claim, these lanes need executed cold/warm evidence with observed time and memory, broader target profiles, exact compatibility matrices, and integration into the measured agent lifecycle.