AGENTS.md — rune

the doctrine of the home is ~/cyber/AGENTS.md; it applies here first. Claude Code receives both files at session start through ~/.config/cyber/agents-md.nu; other agents read them in order.

Git Workflow

• Commit by default. After completing a change, commit it.
• Atomic commits. One logical change per commit.
• Conventional commits. Use prefixes: feat:, fix:, refactor:, docs:, test:, chore:.

Architecture

rune is the open-computation language for cyber's soft3 stack. See ~/cyber/cyber/root/rune.md for the full specification.

Stack position:

cybermark  →  rune inline  →  rune  →  trident  →  Rs

Sibling repos (all at ~/cyber/):

• nox/rs — Nox VM (18-pattern tree-reduction: 16 compute + call + look); added as dep in M6
• trident — compile path substrate; added as dep in M6
• strata — algebra molds (@nebu, @kuro…); added in M3
• hemera/rs — hash primitive; added in M2
• zheng — prover; added in M9

Layout

The workspace root is the project root (rune/Cargo.toml) — run cargo from there. Library crates live under rs/; the CLI is a top-level member at cli/ (hemera-style). No src/ subdir — lib.rs/main.rs sit at each crate root. Folders are bare; package names keep the rune- prefix (folder rs/ast → package rune-ast). Docs live at the project root: specs/, docs/, .claude/.

rs/ast          rune-ast         shared AST (Expr) and Noun types
rs/lex          rune-lex         tokenizer — shared for both registers
rs/parse        rune-parse       parser — classic (rust) register
rs/parse-pure   rune-parse-pure  parser — pure register (all 25 digraphs)
rs/lower        rune-lower       Expr → Nox noun
rs/interp       rune-interp      tree-walking Nox interpreter (instant start) + Host/acts
rs/subject      rune-subject     subject model (~self ~now ~here ~world …)
rs/mold         rune-mold        mold system (types as normalizing functions)
rs/prysm        rune-prysm       rune↔prysm bridge (chunk-noun → tape::Chunk)
rs/compile      rune-compile     compile tier — TierRouter, ArtifactCache (M6)
cli             rune-cli         CLI binary `rune` (repl / run / eval / fmt / check)

Invariant: Instant Start

Every architectural decision must preserve instant start: parse → lower → interpret begins immediately with no compilation phase. This is the contract. Break it only for the compile back-end (M6), and only as a background path — the interpreter path stays the default.

Shell: Nushell

Use nu -c '...' or nu script.nu for scripting. Reserve bash for git.

Testing

• Unit tests live in the crate they test (#[cfg(test)] in lib.rs)
• Integration tests for the CLI go in rs/cli/tests/
• Snapshot tests (insta) for parser and lowering output
• Every Nox pattern (0–11) must have a unit test in rune-interp