Make the scope bag an object instead of an array

Now that the scope bag is a `Record<string, unknown>`, the lexical symbol
names are always carried alongside their values. This eliminates the need
for the `lexicalSymbols` slot in the wire format block (previously only
available when `debugSymbols` was enabled) and allows `meta()` to derive
`lexical` names and `scopeValues` directly from the scope object's keys
and values.

See also: upstream PR #21224, PR #21068.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

Author: NullVoxPopuli

packages/@glimmer-workspace/integration-tests/lib/compile.ts

@@ -15,8 +15,6 @@ export function preprocess(templateSource: string, options?: PrecompileOptions):
   return createTemplate(templateSource, options)({});
 }
 
-let templateId = 0;
-
 export function createTemplate(
   templateSource: Nullable<string>,
   options: PrecompileOptions | PrecompileOptionsWithLexicalScope = {},
@@ -29,12 +27,7 @@ export function createTemplate(
     reifiedScope[key] = scopeValues[key];
   }
 
-  if ('emit' in options && options.emit?.debugSymbols) {
-    block.push(usedLocals);
-  }
-
   let templateBlock: SerializedTemplateWithLazyBlock = {
-    id: String(templateId++),
     block: JSON.stringify(block),
     moduleName: options.meta?.moduleName ?? '(unknown template module)',
     scope: usedLocals.length > 0 ? () => reifiedScope : null,

packages/@glimmer/compiler/lib/compiler.ts

@@ -123,9 +123,8 @@ export function precompile(
 ): TemplateJavascript {
   const [block, usedLocals] = precompileJSON(source, options);
 
-  if ('emit' in options && options.emit?.debugSymbols && usedLocals.length > 0) {
-    block.push(usedLocals);
-  }
+  // lexical symbol names are now carried by the scope object itself (as keys),
+  // so we no longer need to push them into the wire format block for debug symbols.
 
   const moduleName = options.meta?.moduleName;
   const idFn = options.id || defaultId;

packages/@glimmer/interfaces/lib/compile/wire-format/api.d.ts

@@ -373,7 +373,6 @@ export type SerializedTemplateBlock = [
   statements: Statements.Statement[],
   locals: string[],
   upvars: string[],
-  lexicalSymbols?: string[],
 ];
 
 /**

packages/@glimmer/opcode-compiler/lib/opcode-builder/helpers/shared.ts

@@ -106,14 +106,14 @@ export function CompilePositional(
 }
 
 export function meta(layout: LayoutWithContext): BlockMetadata {
-  let [, locals, upvars, lexicalSymbols] = layout.block;
+  let [, locals, upvars] = layout.block;
   let scopeRecord = layout.scope?.() ?? null;
 
   return {
     symbols: {
       locals,
       upvars,
-      lexical: scopeRecord ? Object.keys(scopeRecord) : lexicalSymbols,
+      lexical: scopeRecord ? Object.keys(scopeRecord) : undefined,
     },
     scopeValues: scopeRecord ? Object.values(scopeRecord) : null,
     isStrictMode: layout.isStrictMode,