Midnight Compact Smart Contract Skill

An Agent Skill for writing, testing, and deploying Compact smart contracts on the Midnight blockchain. Built from Discord community knowledge, compiler validation, and real-world gotchas. This project extends the Midnight Network with additional developer tooling.

Supports Claude Code, Cursor, Gemini CLI, VS Code Copilot, and 30+ other AI coding assistants.

Important: These examples are educational references. Any smart contract generated using this skill should be professionally audited before deployment to mainnet. AI-assisted code generation does not replace security review.

Compiler-Validated

All examples compiled and tested against Compact 0.31.1 (compact-runtime 0.16.0, ledger v8). Also compatible with Compact 0.29.0 (ledger v7). See gotcha #74 for migration guide.

✅ Re-validated 2026-08-17 — all 29 examples compile on Compact 0.31.1

Every published example was recompiled from source against the current compiler.

set	result
10 standalone validation contracts	10/10 PASS
19 remaining + new contracts	19/19 PASS
vendored OpenZeppelin compact-contracts	9/10 — see below

Toolchain: compact CLI 0.5.2, compiler 0.31.1, compact-runtime 0.16.0, Midnight.js 4.1.1, Node 1.0.2 (mainnet + preprod; preview 1.0.1), Ledger 8.1.0. (support matrix)

⚠ compact --version reports the CLI wrapper (0.5.1), not the compiler (0.31.1). Easy to confuse when checking which you are on.

🔴 Compact 0.31.0 has a soundness bug that can silently drop a range constraint. Use 0.31.1+. If you deployed anything built with 0.31.0, diff the verifier key — source review is explicitly not reliable for finding it. Details in SKILL.md.

Breaking changes found, and what they mean for older code:

• CoinInfo is now an unbound identifier — hit by OZ’s archive/ShieldedToken.compact, which upstream has already retired. Expected, not a regression, but relevant to anyone carrying older Zswap coin code.
• Zswap operators were renamed: receive → receiveShielded, sendImmediate → sendImmediateShielded. The compiler names the replacement in the error, so this migrates cleanly. All current examples already use the new names.

The per-example test counts in the table below were measured in March against Compact 0.29.0/0.30.0; compilation only was re-verified on 2026-08-17. The suites themselves were re-run on 2026-08-30 — see below.

✅ Re-validated 2026-08-30 — all 11 suites re-run, 676 tests passing

Not a recompile this time: every test suite was executed.

set	result
10 standalone validation contracts	10/10 suites, 69 tests PASS