Share host-aware completion across runtimes

packages/decodal-wasm/README.md

@@ -2,7 +2,7 @@
 
 WebAssembly runtime package for Decodal.
 
-This package exposes the Decodal evaluator to browsers and other JavaScript runtimes that can load WebAssembly modules.
+This package exposes the Decodal evaluator and shared language service to browsers and other JavaScript runtimes that can load WebAssembly modules.
 It is generated from the Rust crate in `crates/decodal-wasm` with `wasm-pack` and is used by the official playground.
 
 Use `decodal-codemirror` separately when you need CodeMirror 6 language support.
@@ -22,15 +22,48 @@ deno add jsr:@hare/decodal-wasm
 ## Usage
 
 ```js
-import init, { evaluateProject } from 'decodal-wasm';
+import init, { DecodalLanguageService } from 'decodal-wasm';
 
 await init();
 
-const result = evaluateProject('main.dcdl', JSON.stringify({
-  'main.dcdl': 'Server = { port = Int default 8080; };',
-}));
+const files = {
+  'main.dcdl': 'let schema = import "./schema.dcdl"; in schema.Server',
+  'schema.dcdl': 'Server = App.Server & { port = 8080; };',
+};
+
+const service = new DecodalLanguageService({
+  globals: {
+    App: {
+      Server: {
+        port: { $decodal: 'Int' },
+      },
+    },
+  },
+  loadImport(_currentKey, specifier) {
+    const key = specifier.startsWith('./') ? specifier.slice(2) : specifier;
+    return { kind: 'source', key, name: key, source: files[key] };
+  },
+  completeImport() {
+    return ['./schema.dcdl'];
+  },
+});
+
+const result = service.evaluate('main.dcdl', 'main.dcdl', files['main.dcdl']);
 
 console.log(JSON.parse(result));
+
+const completion = service.complete(
+  'main.dcdl',
+  'App.Server.po',
+  'App.Server.po'.length,
+  false,
+);
+
+console.log(JSON.parse(completion));
 ```
 
-The exported functions return JSON strings so callers can handle diagnostics and successful results without depending on Rust data structures.
+`globals`, `loadImport`, and `completeImport` are host-owned. The package does not assume a filesystem or virtual project model. Import callbacks are synchronous; preload or cache remote content before evaluation.
+
+Plain strings, numbers, booleans, arrays, and objects are concrete host values. Use `{ $decodal: 'String' | 'Int' | 'Float' | 'Bool' }` for primitive schemas and `{ $decodal: 'Array', item: value }` for array schemas. Descriptors also accept `constraints` and `default`.
+
+Methods return JSON strings so callers can handle diagnostics and successful results without depending on Rust data structures.