What is Acore?

Acore is an independent declarative language for describing software contracts. Its implementation includes a lexer, parser, evaluator, standard library, diagnostics, and language-server support. A .acore file is source code; it is not the distributable artifact that a consumer locks and runs.

What Acore can describe

backend service routes, models, caching, retry, authentication, validation, streaming, and mock behavior;
durable domain entities, relationships, invariants, projections, and security declarations;
Acore UI trees, typed text and layout, interactions, effects, assets, and target-specific application builds;
typed theme and component-library package consumption;
versioned package boundaries for services, themes, component libraries, database schemas, extensions, and application policies.

Not every kind exposes the same authoring or runtime surface yet. The support matrix gives the current boundary.

Source, package, and application are different artifacts

Form	Purpose	May be changed by a consumer?
`.acore`	Human- and agent-authored declarative source	Yes, inside the source owner's build
`.axiom`	Canonical versioned contract/package	No; select a version and lock it
`.axiomapp`	Built UI application for one or more targets	No; rebuild from source and dependencies

Composition keywords

import "./shared.acore"
amends "axiom-fastapi:./app.py:app"
use contract Billing from "billing" audience "mobile"
use theme AppTheme from "design-system" export "default"

import reuses trusted source within a build.
amends composes an Acore or supported extractor input before building.
use contract consumes a compiled service contract selected by a committed dependency lock.
use theme and use component bind verified exports from typed packages.
extend inherits or promotes a declared value; it does not load a file.

See Imports, contracts, and composition for ownership and trust boundaries.

Acore is optional at integration edges

You do not have to rewrite an entire application. Existing Python and Go services can participate through supported extractors. Existing web, React, Flutter, and Swift applications can use their current integration paths. Acore becomes the common contract layer where declarative behavior and auditable composition are valuable.