Prove clean native release artifacts (#106)

docs/release-artifacts.md

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+# Native release artifact audit
+
+MetaCrate's release gate builds and inspects every release crate and every
+shipped program. The gate proves that the deliverables are native Rust
+artifacts: they neither contain nor load LibreMetaverse assemblies, a CLR or
+Mono host, generated foreign bindings, RPC bridges, downloaded fallbacks, or
+helper subprocesses.
+
+The authoritative inventory and allowlists are
+[`ci/artifact-policy.json`](../ci/artifact-policy.json). Adding a publishable
+crate, binary target, native FFI boundary, copied package input, or offline
+smoke requires an explicit policy update. The auditor rejects an incomplete or
+duplicate inventory.
+
+## Clean Ubuntu prerequisites
+
+The automated gate runs only on `ubuntu-latest`, using Rust 1.97.1 for normal
+release work. Rust 1.96.0 remains a separate minimum-supported-version check;
+it is not used to build these release artifacts. The clean worker installs:
+
+- a C/C++ build toolchain, Clang, CMake, Ninja, `pkg-config`, Python 3, and
+  `curl` for the pinned Skia build/download path;
+- Fontconfig and FreeType development libraries for Skia;
+- OpenJPEG 2.5.4 through `tools/install_openjpeg_2_5_4.sh`; and
+- the distribution Opus development package.
+
+No reference LibreMetaverse checkout, .NET SDK/runtime, Mono installation,
+credentials, `.env` file, or live grid is present. The release runtime smoke is
+deliberately offline. Live OpenSim validation is a separate credentialed gate
+documented in [the live-grid guide](live-grid-smoke.md).
+
+## What the gate verifies
+
+The `artifact-audit` command performs all of these checks and fails closed:
+
+1. Resolve the locked Cargo graph and require all 16 release/source packages to
+   use versioned internal dependencies. Reject known managed-host dependencies.
+2. Scan production Rust and manifest sources for helper processes, runtime
+   loading, managed assemblies, and unreviewed `extern "C"` boundaries. The only
+   native FFI allowlist is the reviewed OpenJPEG and Opus adapters.
+3. Inspect every `.crate` archive with byte and entry limits. Reject path
+   traversal, links, special files, managed-code extensions, forbidden runtime
+   markers, and retained workspace dependency paths.
+4. Extract the packages into a new temporary workspace and build every library
+   and binary offline. All internal crates are resolved from the extracted
+   archives and `METACRATE_REFERENCE_ROOT` points to a path that cannot exist.
+5. Parse each executable as ELF, PE, or Mach-O and record imported symbols and
+   linked libraries. Reject forbidden CLR/Mono/LibreMetaverse markers.
+6. Remove all grid credentials, install traps for common managed/download
+   helpers, disable external networking with invalid proxy endpoints, run
+   `--help` for every binary, and execute the declared deeper fake/offline
+   smokes. A helper invocation, timeout, external-service dependency, or absent
+   required output fails the audit.
+
+The resulting JSON records the source commit, exact Rust compiler, host,
+package and executable hashes, binary formats, linked libraries, import counts,
+runtime smoke results, and zero forbidden findings. It is created with
+create-new semantics so prior evidence cannot be silently overwritten.
+
+## Reproducing the gate
+
+After installing the prerequisites above, package all release members in one
+Cargo invocation. Atomic packaging lets Cargo resolve the versioned internal
+crate set exactly as a registry publication batch would:
+
+```sh
+cargo package --locked --no-verify \
+  -p libremetaverse-types -p libremetaverse-structured-data \
+  -p libremetaverse-imaging -p libremetaverse-imaging-skia \
+  -p libremetaverse-openjpeg -p libremetaverse-opus \
+  -p libremetaverse-prim-mesher -p libremetaverse-lsl-tools \
+  -p libremetaverse -p libremetaverse-rendering-simple \
+  -p libremetaverse-rendering-mesh-foundry -p libremetaverse-rlv \
+  -p libremetaverse-utilities -p libremetaverse-voice-vivox \
+  -p libremetaverse-voice-webrtc -p libremetaverse-programs
+
+METACRATE_RUST_COMMIT=$(git rev-parse --verify HEAD) \
+  cargo build --locked --release -j 1 -p libremetaverse-programs --bins
+
+cargo run --locked -p metacrate-ci-matrix -- artifact-audit \
+  --artifact-dir target/release \
+  --package-dir target/package \
+  --evidence artifacts/release/artifact-audit.json
+```
+
+`--no-verify` prevents Cargo from building each archive redundantly. It does
+not skip release verification: the following audit extracts all archives and
+performs one stricter offline build of the complete package set. The generated
+core is large, so the workspace release profile uses bounded optimization and
+single-job CI to remain within an 8 GiB clean worker.