aontu

Your agents write the code. aontu holds the definition.

aontu defines the entities in a software system, their types, and the relations between them. Use it to check changes proposed by a coding agent: a change is admitted or refused, with the source line named when a constraint fails.

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Write down what the system is

Define which fields a service needs and what values they allow. Types, defaults, and data use the same notation, so you can write them in one document and check them together.

type() marks spec as schema and keeps it out of the output. &: $.spec.service applies that schema to every service, including entries you add later. tier:*1 supplies a default: api gets 1, auth specifies 3, and a tier of the wrong kind is refused.

system.aon
spec: type({ service:{ owner:string tier:*1 } })

services: { &: $.spec.service }
services: api: owner: "platform"
services: auth: { owner:"identity" tier:3 }
aontu system.aon
{
  "services": {
    "api":  { "owner": "platform", "tier": 1 },
    "auth": { "owner": "identity", "tier": 3 }
  }
}

Check relations between services

Add calls, a relation that must stay acyclic, then make the two services call each other. The document fails to evaluate because the calls form a cycle. The refusal names the edge, $.services.api.calls.0, and points to the constraint:

the edge an agent added
spec: type({ service:{ owner:string tier:*1 calls?:rel() & acyclic() } })

services: { &: $.spec.service }
services: api: { owner:"platform" calls:[path($.services.auth)] }
services: auth: { owner:"identity" calls:[path($.services.api)] }
aontu system.aon → exit 1
[aontu/relation_cycle]: Cannot relate value at path $.services.api.calls.0

 Cannot relate value: path($.services.auth)
  --> system.aon:1:52
  1 | spec: type({ service:{ owner:string tier:*1 calls?:rel() & acyclic() } })
                                                         ^ value was: path($.services.auth)

The refusal includes the relation_cycle error code, a class, and an exit status. A repair loop can use these to decide what to fix. The error-code reference lists each class and the action it calls for.

23 verbs for checking and changing a model

Validate data, query a path, explain a value, and check whether a schema change breaks compatibility. The TypeScript and Go command lines are checked against one shared test suite. See the reference for each command's output formats and exit codes.

vet
does this data satisfy the schema?
get
what does it say at a path?
why
why does that value hold, and who set it?
set
change one value in an overlay, or in place
subsume
is this schema a widening of that one?
breaking
which changes break an earlier version?
trim
which entries are redundant?
relations
run the declared identity checks
hash
pin what a document means, not how it is spelled
mod
maintain a dependency closure
agentsmd
write the AGENTS.md stanza for a definition
reaches
is there a path from one entity to another?
view
draw the model: tree, graph, matrix, layers, poset
jsonschema
export the model, and name what the export cannot carry
render
write the files the model says to write
template
read a generator written in the target's own syntax
allow
may this role read that path?
fmt
one agreed form for the source, so layout is never argued about
init
scaffold a model, some data, and the checks that hold them
explain
what does this error code mean?
help
the verbs, and the topics behind them
lsp
the language server, for an editor
mcp
the same reports, over stdio, for an agent

Every flag and exit code is in the API and CLI reference. With no file, aontu starts a REPL.

Made to be driven by a program

An agent can retrieve a path, ask which source lines contributed to a value, and propose an edit. The CLI provides these operations, and every page on this site is also available as markdown.

Evaluation limits

aontu has no user-defined functions, clock, or randomness. Evaluation runs within configured budgets. The trust contract states the conditions for termination, deterministic output, and access to files or host values.

Statements combine by unification. Compatible statements narrow the result; contradictory statements produce an error. Adding a statement later does not give it priority over an earlier one.

Install

npm
npm install aontu@0.62.0
Go
go install github.com/aontu-lang/aontu/go/cmd/aontu@latest

MIT licensed. Source, issues and the design record are on GitHub.