fix: deduplicate CodeMirror completion state

web/workspace/test/config-source/editor-state.test.ts

@@ -1,3 +1,5 @@
+import { CODEMIRROR_VITE_DEDUPE } from "../../src/lib/workspace/config-source/vite-dedupe.ts";
+
 declare const Deno: {
   test(name: string, fn: () => Promise<void> | void): void;
   readTextFile(path: URL): Promise<string>;
@@ -7,6 +9,23 @@ function assert(condition: unknown, message: string): asserts condition {
   if (!condition) throw new Error(message);
 }
 
+Deno.test("Vite deduplicates CodeMirror stateful packages", () => {
+  for (
+    const packageName of [
+      "@codemirror/autocomplete",
+      "@codemirror/language",
+      "@codemirror/state",
+      "@codemirror/view",
+      "@lezer/common",
+    ]
+  ) {
+    assert(
+      CODEMIRROR_VITE_DEDUPE.includes(packageName),
+      `Vite must deduplicate ${packageName}`,
+    );
+  }
+});
+
 Deno.test("config editor snapshots Svelte proxies before cloning baselines", async () => {
   const source = await Deno.readTextFile(
     new URL(
@@ -72,6 +91,13 @@ Deno.test("Decodal editor follows readonly prop changes after mount", async () =
       !source.includes("--border-subtle"),
     "CodeMirror theme must use workspace tokens that actually exist",
   );
+  assert(
+    source.includes("keymap.of(completionKeymap)") &&
+      source.includes("startCompletion(editor)") &&
+      source.includes("update.selectionSet && !update.docChanged") &&
+      source.includes("completionStatus(editor.state) === null"),
+    "completion should be explicitly available and start when an editable cursor moves into an empty schema position",
+  );
   assert(
     source.includes("fixedSchemaWrapperCompartment.reconfigure") &&
       source.includes("fixedSchemaWrapperExtension()") &&

web/workspace/test/config-source/toolchain.test.ts

@@ -67,10 +67,9 @@ Deno.test("toolchain converts reactive-like proxies to plain Worker messages", a
   );
 });
 
-Deno.test("toolchain adapts WASM completion items and byte offsets for CodeMirror", () => {
-  const source = "let 名 = tru";
-  const result = toCodeMirrorCompletion(source, {
-    from: new TextEncoder().encode("let 名 = ").length,
+Deno.test("toolchain preserves WASM UTF-16 completion ranges for CodeMirror", () => {
+  const result = toCodeMirrorCompletion({
+    from: "let 名 = ".length,
     items: [
       {
         label: "true",
@@ -84,7 +83,7 @@ Deno.test("toolchain adapts WASM completion items and byte offsets for CodeMirro
   assert(result !== null, "WASM completion should produce a CodeMirror result");
   assert(
     result.from === "let 名 = ".length,
-    "byte offsets should become UTF-16 offsets",
+    "WASM UTF-16 offsets should be preserved for CodeMirror",
   );
   assert(
     result.options.length === 1,