`--emit-attest` (binary attestation sidecar)

perry compile --emit-attest main.ts -o myapp writes myapp.attest.json next to the executable. The sidecar holds the SHA-256 of the post-strip / post-codesign binary plus provenance metadata (perry version, git commit, build timestamp) so downstream consumers can verify that the artifact they downloaded matches the one the publisher built. (#504)

Why

Publishing a Perry binary to a CDN, a release page, or an internal artifact registry creates a window between “publisher built it” and “user runs it.” --emit-attest produces a JSON sidecar that anyone can recompute on the downloaded artifact and compare. A tampered or swapped binary fails verification with a verbose diagnostic that reproduces both hashes.

Emit

perry compile --emit-attest main.ts -o myapp
# → myapp
# → myapp.attest.json

Equivalent settings, last wins:

perry.emitAttest: true in host package.json.
PERRY_EMIT_ATTEST=1 in the environment.
--emit-attest on the CLI.

=0 / false explicitly disables (so a CI matrix can override a host-level opt-in).

Verify

perry verify --attest ./myapp

Streams SHA-256 of the binary on disk and compares against myapp.attest.json. Output:

match — prints ✓ attestation matches plus the captured provenance (perry version, commit SHA, build timestamp). Exit 0.
mismatch — prints both hashes, the sidecar’s provenance, and exit 1.
missing sidecar — prints actionable guidance pointing at --emit-attest. Exit 1.

The verifier runs offline (no tokio runtime, no network, no beta consent prompt) — distinct from the existing perry verify which goes through verify.perryts.com for runtime verification.

Manifest shape

{
  "version": 1,
  "sha256": "abcd1234...",
  "size": 1048576,
  "perry_version": "0.5.999",
  "commit_sha": "0a1b2c3...",
  "built_at_unix": 1715990400,
  "binary_filename": "myapp"
}

version: 1 reserves room for future top-level keys (CI signature blob, sigstore bundle, reproducible-builds flags log) without breaking existing parsers.

When the hash is captured

The hash is computed after every post-link rewrite the platform applies — strip, codesign, install_name_tool retag, ad-hoc extended-attribute scrubs. That’s the same byte sequence users download, so the recomputed hash matches when the artifact is intact.

Cross-platform

The hook lives in the platform-agnostic compile_command driver, so every backend (LLVM, WASM, ArkTS, HarmonyOS, Glance, SwiftUI, JS) emits the sidecar consistently.

Follow-ups (MVP scope)

The MVP captures hash + provenance. Full reproducible-builds and sigstore-style remote signature publication are tracked separately under the same issue.

Perry Documentation