v0.74.0

Added

• localharness acp — the agent is now an Agent Client Protocol server.
  ACP (JSON-RPC 2.0 over newline-delimited stdio; governed by Zed + JetBrains)
  is the editor↔agent standard whose registry is the de-facto "compatible
  harness list" — it is what Buzz's buzz-acp bridge consumes. localharness acp [--as <name>] [--model <id>] serves this identity's agent behind that
  seam: initialize / session/new / session/prompt with streamed
  session/update notifications / session/cancel. Sessions ride the same
  headless metered path as call — on-chain persona + lessons + skills, every
  prompt a metered $LH turn — via the new start_headless_agent(…, multi_turn) front-half, which forces the METER path (an x402 one-shot nonce
  cannot survive a second prompt). Stdout is the wire (one flushed frame per
  line); stdin EOF mid-turn means "no more requests", not cancel, so scripted
  printf | acp sessions drain cleanly. Proven live on mainnet: a two-prompt
  session streamed metered turns and held conversation state across them.
• Execution receipts v1 (localharness::receipt, feature wallet): a
  hash-committed record that a specific deterministic computation happened —
  versioned canonical preimage (length-prefixed, no JSON in the hash), keccak
  receipt hash, and a CallRecord shape ready for browser-side
  compose::call emission. localharness receipt <src.rl> [--check <0xhash>]
  emits/verifies the BUILD receipt (source → wasm binding; the compiler is
  deterministic, so the same version reproduces the same receipt) — a
  regression pin for published cartridges. Browser-side call-receipt emission
  and any anchoring/dispute machinery are deferred, explicitly.
• Proxy accepts the x402 v2 standard header. The 2025-12-11 x402 v2 spec
  renamed the wire headers; both proxy read sites now accept
  payment-signature alongside the legacy x-payment /
  x-x402-authorization, so a v2-conformant external agent can pay our
  endpoints. The CLI keeps sending the legacy name (renaming the emit side
  would break deployed callers). Proxy deployed separately, live-verified.
• design/harness-landscape-2026.md — the field brief this release ships
  against: every major harness surveyed live (2026-07-29), four corrections to
  our own working map, the standards gap (ACP / Agent Skills), and the
  skill-supply-chain evidence behind the receipts primitive.