@mosaicjs/core

The framework-agnostic heart of Mosaic: the IR types, the Mosaic compiler (Mosaic -> IR), validate, resolve, the expr evaluator, walk(), the block registry, and the Host Manifest.

Status: implemented. The compiler, the expr evaluator, validation, resolution, and walk() are real; every example in examples/ parses, validates, resolves, and round-trips through the canonical serialization under test.

This is the one package everything else depends on. It absorbs what were separate @mosaicjs/wire (compile), @mosaicjs/schema (registry + validate), and @mosaicjs/host (manifest + theme) packages - the IR is small enough that splitting them added surface without value.

• IR - MosaicNode, MosaicDocument, Directives, JsonLiteral (docs/proposal.md §4).
• Compile - parse / serialize (Mosaic -> IR and the IR's canonical JSON serialization); loadMosaic / saveMosaic read and write fenced .mosaic source (§5).
• expr - evalExpr, the bounded CEL-class expression language behind from:expr / if:show / for:each (§6.2). AST-interpreted, never eval.
• walk - walk(doc, visitor, manifest), the portable contract every framework implements (§7.2).
• Manifest - HostManifest, DEFAULT_MANIFEST, compactManifest (§3.3); plus Theme, DEFAULT_THEME, and resolveToken for renderers that take a token→value map.

A non-React framework imports from here and implements a NodeVisitor over the IR; @mosaicjs/react is the worked example.