magus v0.4.3 is out. See what's new
¶ View markdown source · ✎ Suggest an edit
2 min read

interpreter-rewrite

A deny rule by default: it refuses an inline interpreter rewriting a file this tree already carries, and names what to run instead.

What it catches

An inline interpreter rewriting a file this tree already carries.

Why

A python -c or node -e that reads a tracked file, substitutes, and writes it back is an edit nobody reviewed: it lands before a diff exists, and the script that produced it is gone the moment the line ends. The editor tool reads the file first and reports what it changed, which is the same edit with a record of itself. It fires on the WRITE, not the interpreter: a one-liner that computes something, prints it, or creates a file the tree does not carry is untouched, and so is anything under a scratch path. Only a write's destination counts: the path an open(..., 'w'), a pathlib or writeFile writer, an in-place flag or an awk redirect names, a variable read through its assignment. A tracked path the program carries as data, in a list it prints to stdout or a report it writes to scratch, is not one. A destination spelled from no literal at all, such as argv, is read as the interpreter's operands.

Default and override

By default this rule takes the decision deny. A workspace sets it by name, in its root magusfile, to deny, advise or off:

magus\guard.builtins({"interpreter-rewrite": "advise"})

A loosening takes effect once it is committed; a tightening applies at once.

Seeing it

A verdict names its rule in brackets, which is how you got here:

deny [interpreter-rewrite]: ...

A workspace that sets this rule to advise sees advise [interpreter-rewrite]: ... instead.

magus describe rule interpreter-rewrite prints the same entry at a terminal, and magus describe rules lists every rule this workspace enforces.

See also

guardrulesinterpreter-rewritedeny
Last updated (c6a327d5)
Earlier changes on this page (4)

Full history ↗ · Blame source ↗

Glossary

Workspace

The magus root directory that owns a set of projects and shared config; the unit magus operates over. Workspace in full.

Magusfile

The magusfile.buzz that declares a project's targets (as export funs) and binds its spells. Magusfile in full.

Op

A single tool-native command a target composes (long form: operation); the middle of the work hierarchy (Spell to Op to Target). Op in full.

Spell

A language/runtime adapter (e.g. go, md) that maps generic targets onto a toolchain's real commands. Spell in full.

Buzz

The language magusfiles are written in (the .buzz engine). Buzz in full.

CI

An ordinary target you compose yourself with ctx.needs; magus does not hardcode its stages. It is the anchor magus affected ci keys off, and ci strips the rw charm. CI in full.

Agent

A model working through an agent host such as Claude Code, Codex, Cursor or OpenCode. magus treats an agent as one more caller of its CLI, MCP tools and console, held to the same checks as a person. Agent in full.

Tool

An action a model can call through its host: a name, a description, a typed input and a result. magus serves its tools over MCP, each a read of the workspace model or a run of the CLI it already has. Tool in full.

Run

One target executing under one magus invocation, such as magus run test web or magus affected ci. A run keeps its captured output behind an output reference. Every magus run is a run whether or not any job asked for it; see Job for how the two relate. Run in full.

Conventions

This page uses none of the site's convention markers. The full set is on the conventions page.