harn-canon

Seed invariant libraries for Harn Flow — the agent-native shipping substrate built into the Harn language.

A repo's canon is the living body of best practices it expects changes to respect. The Archivist persona authors the canon. The Ship Captain persona enforces it.

What lives here

Per-language and per-stack starter predicate packs that any project can opt into. Each pack is a directory containing:

• invariants.harn — Harn functions annotated with @invariant and either @deterministic (pure, 50 ms budget) or @semantic (one cheap LLM judge call, 2 s budget, evidence pre-baked at authoring time).
• README.md — purpose, stack assumptions, evidence sources, coverage examples, known false positives.
• fixtures/ — small atom/slice fixtures the predicates are expected to allow or block, used by CI.

Predicate files use Harn attributes to carry evidence:

@invariant
@deterministic
@archivist(
  evidence = ["https://typescript-eslint.io/rules/no-floating-promises/"],
  confidence = 0.9,
  source_date = "2026-04-24",
)
fn no_floating_promises(slice: Slice, ctx: Context, repo_at_base: Repo) -> InvariantResult {
  // …
}

See the Harn Flow design docs for the full predicate language spec.

Packs

• Harn — v0 draft predicates for .harn scripts, Flow workflows, and agent-facing Harn modules.

Status

🚧 Early — design-first. The predicate language, InvariantResult type, and runtime harness are still being specified in burin-labs/harn. This repo exists now to:

1. Reserve the namespace and let contributors start drafting seed predicates.
2. Collect evidence and discussion per-language independently of the core substrate schedule.
3. Surface a clear contribution path: pick a language, draft 5–10 deterministic + 2–3 semantic predicates, open a PR.

Contributing

See CONTRIBUTING.md. In short: one language per PR, cite evidence ≤18 months old with at least two independent sources (prefer official language/framework docs), and include fixtures.

License

Dual-licensed under Apache-2.0 and MIT, matching the harn repo.