0.3.1 — the adoption release, now on the official MCP Registry

Covers 0.3.0 (2026-07-04, adoption) and 0.3.1 (2026-07-05, the registry listing) — 0.3.0 shipped without release notes, so both are here. No engine changes in either: the 5 MCP tools / 5 CLI commands surface and all response shapes are 0.2.0's.

Run it:

uvx heddle-mcp        # boots the stdio MCP server directly
pip install heddle-mcp

0.3.1 — on the official MCP Registry

• MCP Registry listing — heddle is live as io.github.davet47/heddle: server.json, the mcp-name ownership marker in the README, and a heddle-mcp console script so uvx heddle-mcp works — the registry's launch convention. A launch shim for heddle serve, not a sixth CLI command.
• Registry publishing in CI — an mcp-registry job (GitHub OIDC, no stored secrets) publishes to registry.modelcontextprotocol.io after the PyPI publish succeeds, syncing server.json versions from the tag; the build fails fast if the tag and __version__ disagree. The listing can't go stale.
• The benchmark scorecard — docs/benchmarks.md holds every published token-reduction number, reproducible from this repo alone: the 5.4× DoD gate, full sweeps of all three example projects (3–4×, counting the leaf units the gate doesn't), and the concessions any public claim should carry. bench/sweep.py runs the same accounting over every verifiable unit of any heddle project.

0.3.0 — adoption

Everything a first-time visitor needs that the engine releases didn't ship:

• Heddle develops on heddle — the repo is itself a heddle project: contracts/ holds 12 contracts over the stable seams (the five api.py tool functions, the hashing trio, impl_hash, verification_key, HeddleError, the Store Protocol), bound to the existing test suite. Written status: inferred by the agent, reviewed and confirmed by a human at zero re-verification cost. heddle verify --radius is the inner-loop gate for changes to contracted seams.
• Getting-started walkthrough — docs/getting-started.md: how a human and an agent build a package contract-first — setup, the CLAUDE.md working rules to give the agent, the inferred→confirmed review loop, and the verify --radius gate as the definition of done.
• A TypeScript sample project — examples/ts-cart: 8 contracts over a shopping cart (interface/type-alias contracts included), exercising the TypeScript adapter end to end — canonical-AST impl hashing via the project's own typescript, node:test verification under type stripping.
• A Go sample project — examples/go-ledger: 8 contracts over a small double-entry ledger (struct/type contracts included), exercising the Go adapter end to end — AST-stable impl hashing, go test -json verification.

Full details in CHANGELOG.md.