v0.1.8

Worker boundary: split into three sibling crates

lean-rs-worker is replaced by three crates that separate concerns at the link-graph boundary:

• lean-rs-worker-protocol — wire types and frame codec. Depends only on serde / serde_json. Does not link
  libleanshared. The harness Cargo feature exposes the in-memory frame exerciser and fake-worker test affordances.
  Every public enum and field-bearing struct is #[non_exhaustive] so additive variants do not require a major bump.
• lean-rs-worker-parent — parent-side supervisor, pool, planning, capability, and session. Depends on
  lean-rs-worker-protocol and lean-toolchain. Does not link libleanshared. A parent binary that only depends
  on lean-rs-worker-parent is free to dispatch to per-toolchain worker children at runtime without being rpath-pinned
  at link time. The crate re-exports the wire types that appear in its public signatures so the common path is a single
  dependency.
• lean-rs-worker-child — child runtime and the lean-rs-worker-child binary. Depends on
  lean-rs-worker-protocol, lean-rs, lean-rs-host, and lean-toolchain. The only worker crate that links
  libleanshared. The integration tests, examples, and benchmarks that drive a real Lean runtime live here.

The old lean-rs-worker crate is removed. There is no shim and no compile_error stub; consumers swap
lean-rs-worker = "0.1.7" for lean-rs-worker-parent = "0.1.8" (parent process) and lean-rs-worker-child = "0.1.8"
(worker binary). Import paths shift from lean_rs_worker:: to either lean_rs_worker_parent:: or
lean_rs_worker_protocol:: depending on whether the type is part of the parent surface or the wire surface. The wire
format and protocol version are unchanged; a 0.1.7 child speaks the same frames as a 0.1.8 parent.

The lean-rs-worker-child binary name and on-disk layout are unchanged, so existing
LeanWorkerChild::sibling("lean-rs-worker-child") lookups keep working.

Type promotion to lean-toolchain

LeanBuiltCapability, LeanLibraryDependency, LeanLoaderDiagnosticCode, the LeanCapabilityPreflightReport /
LeanCapabilityPreflightCheck data shapes, and the LEAN_HEARTBEAT_LIMIT_DEFAULT /
LEAN_DIAGNOSTIC_BYTE_LIMIT_DEFAULT constants now live in lean-toolchain. lean-rs re-exports them at their existing
paths for workspace source compatibility. This removes the worker boundary's need to mirror host types and the parity
test that gated drift.

Preflight split

LeanCapabilityPreflight::check() is split into two layers. Static manifest validation (file exists, JSON parses,
schema and fingerprint checks) now lives in lean_toolchain::static_manifest_validation and runs client-side from
lean-rs-worker-parent before any child fork. The heavyweight runtime symbol-table inspection (Mach-O / ELF allowlist
check) stays in lean-rs and runs from the child on first command. The wire-visible
LeanCapabilityPreflightReport shape is unchanged.

Workspace

• All published crates bump to 0.1.8.
• Workspace Cargo.toml registers lean-rs-worker-protocol, lean-rs-worker-parent, and lean-rs-worker-child.
• docs/api-review/ baselines are added for the three new crates; the old lean-rs-worker-public.txt is removed.
• The release workflow publishes lean-rs-worker-protocol → lean-rs-worker-parent → lean-rs-worker-child in
  dependency order in place of the old single lean-rs-worker publish.

Migration

# Cargo.toml — parent process (the common case)
- lean-rs-worker = "0.1.7"
+ lean-rs-worker-parent = "0.1.8"

# Cargo.toml — separate worker binary
+ lean-rs-worker-child = "0.1.8"

// imports — parent surface
- use lean_rs_worker::{LeanWorkerCapability, LeanWorkerCapabilityBuilder, LeanWorkerChild, LeanWorkerPool};
+ use lean_rs_worker_parent::{LeanWorkerCapability, LeanWorkerCapabilityBuilder, LeanWorkerChild, LeanWorkerPool};

// imports — wire types (only when working with the protocol directly)
- use lean_rs_worker::{Request, Response, LeanWorkerElabOptions};
+ use lean_rs_worker_protocol::{Request, Response, LeanWorkerElabOptions};

Test-only helpers move from lean_rs_worker::__test_support to lean_rs_worker_protocol::harness and require the
harness feature on lean-rs-worker-protocol.