fix(typescript): reuse suffix index in scope resolver (#1840)

* fix(typescript): reuse suffix index in scope resolver

Build a suffix index once per TypeScript scope-resolution pass and pass it into standard import resolution so package-style imports avoid repeated linear file-list scans.\n\nFixes #1839

* test(typescript): add wiring-level test for scope-resolver suffix index

- Test typescriptScopeResolver.resolveImportTarget directly (the real
  production entry point) with package-style, unresolvable, and relative
  imports
- Use vi.spyOn on buildSuffixIndex to verify the index is built inside
  the makeTsResolveImportTarget closure — fails if index wiring is removed
- Fix existing test to pass real file lists instead of empty arrays
  alongside the prebuilt index, matching production wiring

---------

Co-authored-by: Gergő Magyar <gergomagyar@icloud.com>
Co-authored-by: Test <test@example.com>

gitnexus/src/core/ingestion/languages/typescript/import-target.ts

@@ -17,6 +17,7 @@
 import type { ParsedImport, WorkspaceIndex } from 'gitnexus-shared';
 import { SupportedLanguages } from 'gitnexus-shared';
 import { resolveImportPath } from '../../import-resolvers/standard.js';
+import type { SuffixIndex } from '../../import-resolvers/utils.js';
 import type { TsconfigPaths } from '../../language-config.js';
 
 export interface TsResolveContext {
@@ -31,6 +32,8 @@ export interface TsResolveContext {
   readonly normalizedFileList?: readonly string[];
   /** Per-call resolution cache to dedupe repeated lookups. */
   readonly resolveCache?: Map<string, string | null>;
+  /** Prebuilt suffix index for O(1)-style package/absolute import matching. */
+  readonly index?: SuffixIndex;
   /** Parsed tsconfig path-aliases. `null` = no aliases configured. */
   readonly tsconfigPaths?: TsconfigPaths | null;
   /** JavaScript vs TypeScript switch — affects the extensions the
@@ -84,6 +87,7 @@ export function resolveTsTarget(targetRaw: string, ctx: TsResolveContext): strin
     resolveCache,
     language,
     ctx.tsconfigPaths ?? null,
+    ctx.index,
   );
 }
 

gitnexus/src/core/ingestion/languages/typescript/scope-resolver.ts

@@ -19,6 +19,7 @@ import { populateClassOwnedMembers } from '../../scope-resolution/scope/walkers.
 import type { ScopeResolver } from '../../scope-resolution/contract/scope-resolver.js';
 import { typescriptProvider } from '../typescript.js';
 import { loadTsconfigPaths, type TsconfigPaths } from '../../language-config.js';
+import { buildSuffixIndex, type SuffixIndex } from '../../import-resolvers/utils.js';
 import {
   typescriptArityCompatibility,
   typescriptMergeBindings,
@@ -50,6 +51,7 @@ function makeTsResolveImportTarget(): ScopeResolver['resolveImportTarget'] {
     readonly allFilePaths: Set<string>;
     readonly allFileList: readonly string[];
     readonly normalizedFileList: readonly string[];
+    readonly index: SuffixIndex;
     readonly resolveCache: Map<string, string | null>;
   }
   let cached: PassCache | null = null;
@@ -57,11 +59,13 @@ function makeTsResolveImportTarget(): ScopeResolver['resolveImportTarget'] {
   return (targetRaw, fromFile, allFilePaths, resolutionConfig) => {
     if (cached === null || cached.key !== allFilePaths) {
       const allFileList = Array.from(allFilePaths);
+      const normalizedFileList = allFileList.map((f) => f.toLowerCase());
       cached = {
         key: allFilePaths,
         allFilePaths: new Set(allFilePaths),
         allFileList,
-        normalizedFileList: allFileList.map((f) => f.toLowerCase()),
+        normalizedFileList,
+        index: buildSuffixIndex(normalizedFileList, allFileList),
         resolveCache: new Map(),
       };
     }
@@ -72,6 +76,7 @@ function makeTsResolveImportTarget(): ScopeResolver['resolveImportTarget'] {
       allFilePaths: cached.allFilePaths,
       allFileList: cached.allFileList,
       normalizedFileList: cached.normalizedFileList,
+      index: cached.index,
       resolveCache: cached.resolveCache,
       tsconfigPaths: cfg?.tsconfigPaths ?? null,
     };

gitnexus/test/unit/scope-resolution/typescript/typescript-imports.test.ts

@@ -6,7 +6,7 @@
  * set of fake file paths (with and without tsconfig path aliases).
  */
 
-import { describe, it, expect } from 'vitest';
+import { describe, it, expect, vi, afterEach } from 'vitest';
 import { emitTsScopeCaptures } from '../../../../src/core/ingestion/languages/typescript/captures.js';
 import { splitImportStatement } from '../../../../src/core/ingestion/languages/typescript/import-decomposer.js';
 import { interpretTsImport } from '../../../../src/core/ingestion/languages/typescript/interpret.js';
@@ -14,6 +14,9 @@ import {
   resolveTsImportTarget,
   type TsResolveContext,
 } from '../../../../src/core/ingestion/languages/typescript/import-target.js';
+import { buildSuffixIndex } from '../../../../src/core/ingestion/import-resolvers/utils.js';
+import * as importResolverUtils from '../../../../src/core/ingestion/import-resolvers/utils.js';
+import { typescriptScopeResolver } from '../../../../src/core/ingestion/languages/typescript/scope-resolver.js';
 import type { SyntaxNode } from '../../../../src/core/ingestion/utils/ast-helpers.js';
 import type { ParsedImport, WorkspaceIndex } from 'gitnexus-shared';
 import { SupportedLanguages } from 'gitnexus-shared';
@@ -399,4 +402,68 @@ describe('resolveTsImportTarget — standard suffix + alias resolution', () => {
     );
     expect(result).toBe('src/a.js');
   });
+
+  it('uses a prebuilt suffix index for package-style imports', () => {
+    const parsed: ParsedImport = {
+      kind: 'named',
+      localName: 'Button',
+      importedName: 'Button',
+      targetRaw: 'components/Button',
+    };
+    const files = ['src/main.ts', 'src/components/Button.ts'];
+    const index = buildSuffixIndex(
+      files.map((f) => f.toLowerCase()),
+      files,
+    );
+    const result = resolveTsImportTarget(
+      parsed,
+      ctx('src/main.ts', files, {
+        allFileList: files,
+        normalizedFileList: files.map((f) => f.toLowerCase()),
+        index,
+      }),
+    );
+
+    expect(result).toBe('src/components/Button.ts');
+  });
+});
+
+describe('typescriptScopeResolver.resolveImportTarget — real wiring', () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it('builds suffix index and resolves package-style imports through the production path', () => {
+    const spy = vi.spyOn(importResolverUtils, 'buildSuffixIndex');
+    const files = new Set(['src/main.ts', 'src/components/Button.ts']);
+
+    const result = typescriptScopeResolver.resolveImportTarget!(
+      'components/Button',
+      'src/main.ts',
+      files,
+    );
+
+    expect(result).toBe('src/components/Button.ts');
+    expect(spy).toHaveBeenCalled();
+  });
+
+  it('returns null for unresolvable package-style imports', () => {
+    const files = new Set(['src/main.ts', 'src/utils/helper.ts']);
+
+    const result = typescriptScopeResolver.resolveImportTarget!(
+      'nonexistent/Module',
+      'src/main.ts',
+      files,
+    );
+
+    expect(result).toBeNull();
+  });
+
+  it('resolves relative imports through the scope-resolver entry point', () => {
+    const files = new Set(['src/main.ts', 'src/utils.ts']);
+
+    const result = typescriptScopeResolver.resolveImportTarget!('./utils', 'src/main.ts', files);
+
+    expect(result).toBe('src/utils.ts');
+  });
 });