test(resolution): a builtin method call must not land on another file's closure

The two-file reachability fixture from #1709: a `function text()` nested in
one file, a `settled.value.text()` call in another. The caller must not get
a `calls` edge onto the closure; the in-container call still resolves.

__tests__/fuzzy-lexical-reach.test.ts

@@ -0,0 +1,73 @@
+/**
+ * A function nested inside another function is only callable from inside its
+ * container. matchByExactName already filters candidates that way; matchFuzzy
+ * must too, or a call to a builtin method (`res.text()`) whose only same-named
+ * project symbol is some file's closure resolves onto that closure.
+ */
+
+import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
+import { CodeGraph } from '../src';
+
+describe('fuzzy matching respects lexical reachability of nested functions', () => {
+  let tempDir: string;
+  let cg: CodeGraph | null = null;
+
+  beforeEach(() => {
+    tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'codegraph-fuzzy-reach-'));
+  });
+
+  afterEach(() => {
+    cg?.destroy();
+    cg = null;
+    try {
+      fs.rmSync(tempDir, { recursive: true, force: true });
+    } catch {
+      // Windows can still hold the SQLite handle for a moment; the OS temp dir is swept anyway.
+    }
+  });
+
+  it('does not resolve a builtin method call onto another file\'s closure of the same name', async () => {
+    fs.writeFileSync(
+      path.join(tempDir, 'seed.ts'),
+      [
+        'export function readSeedState(raw: string): string {',
+        '  function text(): string {',
+        '    return raw.trim();',
+        '  }',
+        '  return text();',
+        '}',
+        '',
+      ].join('\n')
+    );
+    fs.writeFileSync(
+      path.join(tempDir, 'fetch.ts'),
+      [
+        'export async function readOkText(settled: { value: Response }): Promise<string> {',
+        '  // A chained receiver reaches the resolver as the bare method name.',
+        '  return settled.value.text();',
+        '}',
+        '',
+      ].join('\n')
+    );
+    cg = await CodeGraph.init(tempDir, { index: true });
+    cg.resolveReferences();
+
+    const closure = cg
+      .getNodesByKind('function')
+      .find((n) => n.name === 'text' && n.filePath === 'seed.ts');
+    const caller = cg.getNodesByKind('function').find((n) => n.name === 'readOkText');
+    expect(closure).toBeDefined();
+    expect(caller).toBeDefined();
+
+    const fromCaller = cg.getOutgoingEdges(caller!.id).filter((e) => e.kind === 'calls');
+    expect(fromCaller.map((e) => e.target)).not.toContain(closure!.id);
+
+    // The in-container call still resolves.
+    const container = cg.getNodesByKind('function').find((n) => n.name === 'readSeedState');
+    const inside = cg.getOutgoingEdges(container!.id).filter((e) => e.kind === 'calls');
+    expect(inside.map((e) => e.target)).toContain(closure!.id);
+  });
+});