diff --git a/gitnexus/src/core/ingestion/entry-point-scoring.ts b/gitnexus/src/core/ingestion/entry-point-scoring.ts
index 58cf9389c..30a9c78c1 100644
--- a/gitnexus/src/core/ingestion/entry-point-scoring.ts
+++ b/gitnexus/src/core/ingestion/entry-point-scoring.ts
@@ -13,6 +13,7 @@
 import { detectFrameworkFromPath } from './framework-detection.js';
 import { SupportedLanguages } from 'gitnexus-shared';
 import { providers } from './languages/index.js';
+import { isTestFilePath } from './utils/test-file-path.js';
 
 // ============================================================================
 // NAME PATTERNS
@@ -164,54 +165,15 @@ export function calculateEntryPointScore(
 // ============================================================================
 
 /**
- * Check if a file path is a test file (should be excluded from entry points)
- * Covers common test file patterns across all supported languages
+ * Check if a file path is a test file (should be excluded from entry points).
+ *
+ * Delegates to the shared predicate in `utils/test-file-path.ts`. This used to be
+ * a second, hand-maintained copy that had drifted from the one backing the MCP
+ * `includeTests` flag — see that module's header. Re-exported under this name so
+ * existing importers are unaffected.
  */
 export function isTestFile(filePath: string): boolean {
-  const p = filePath.toLowerCase().replace(/\\/g, '/');
-
-  return (
-    // JavaScript/TypeScript test patterns
-    p.includes('.test.') ||
-    p.includes('.spec.') ||
-    p.includes('__tests__/') ||
-    p.includes('__mocks__/') ||
-    // Generic test folders
-    p.includes('/test/') ||
-    p.includes('/tests/') ||
-    p.includes('/testing/') ||
-    // Python test patterns
-    p.endsWith('_test.py') ||
-    p.includes('/test_') ||
-    // Go test patterns
-    p.endsWith('_test.go') ||
-    // Java test patterns
-    p.includes('/src/test/') ||
-    // Rust test patterns (inline tests are different, but test files)
-    p.includes('/tests/') ||
-    // Swift/iOS test patterns
-    p.endsWith('tests.swift') ||
-    p.endsWith('test.swift') ||
-    p.includes('uitests/') ||
-    // C# test patterns
-    p.endsWith('tests.cs') ||
-    p.endsWith('test.cs') ||
-    p.includes('.tests/') ||
-    p.includes('.test/') ||
-    p.includes('.integrationtests/') ||
-    p.includes('.unittests/') ||
-    p.includes('/testproject/') ||
-    // PHP/Laravel test patterns
-    p.endsWith('test.php') ||
-    p.endsWith('spec.php') ||
-    p.includes('/tests/feature/') ||
-    p.includes('/tests/unit/') ||
-    // Ruby test patterns
-    p.endsWith('_spec.rb') ||
-    p.endsWith('_test.rb') ||
-    p.includes('/spec/') ||
-    p.includes('/test/fixtures/')
-  );
+  return isTestFilePath(filePath);
 }
 
 /**
diff --git a/gitnexus/src/core/ingestion/utils/test-file-path.ts b/gitnexus/src/core/ingestion/utils/test-file-path.ts
new file mode 100644
index 000000000..ceee59c56
--- /dev/null
+++ b/gitnexus/src/core/ingestion/utils/test-file-path.ts
@@ -0,0 +1,87 @@
+/**
+ * Test-file path classification — the single source of truth.
+ *
+ * WHY THIS MODULE EXISTS
+ *
+ * Two independent copies of this predicate existed and had drifted apart:
+ *
+ *   - `core/ingestion/entry-point-scoring.ts` `isTestFile`  — excludes test
+ *     files from process entry-point detection.
+ *   - `mcp/local/local-backend.ts` `isTestFilePath`         — backs the
+ *     `includeTests` flag on `impact` / `trace` / `context`.
+ *
+ * They answered "is this a test file?" differently, so the same path could be a
+ * test in one code path and not the other. The MCP copy recognized no C#, Java,
+ * or Swift test convention at all, meaning `includeTests: false` silently failed
+ * to filter them; the scoring copy missed `/conftest.` (it already matched
+ * `/test/`, so `/test/fixtures/` was never a scoring gap).
+ *
+ * The duplication was not gratuitous: `entry-point-scoring.ts` imports the
+ * language-provider registry, and #2802 deliberately cut that closure out of MCP
+ * server startup. Importing it back into `local-backend.ts` would reintroduce
+ * that cost. So the shared predicate lives here instead, with NO imports — pure
+ * string matching — and both callers delegate to it.
+ *
+ * Keep it dependency-free. Anything imported here lands in MCP startup.
+ */
+
+/**
+ * Lowercase forward-slash path substrings. Directory needles include a leading
+ * slash so they match path components after the caller slash-prefixes relative
+ * paths. `/test/` already covers Maven `src/test` and `/test/fixtures/`;
+ * `/tests/` covers Laravel `tests/Feature` and `/tests/fixtures/`.
+ */
+const TEST_PATH_SUBSTRINGS: readonly string[] = [
+  '.test.',
+  '.spec.',
+  '__tests__/',
+  '__mocks__/',
+  '/test/',
+  '/tests/',
+  '/testing/',
+  '/spec/',
+  '/test_',
+  '/conftest.',
+  '/uitests/',
+  '.tests/',
+  '.test/',
+  '.integrationtests/',
+  '.unittests/',
+  '/testproject/',
+];
+
+/** Case-insensitive suffixes that already include a delimiter (`_test.py`, not `test.py`). */
+const TEST_PATH_DELIMITED_SUFFIXES: readonly string[] = [
+  '_test.py',
+  '_test.go',
+  '_spec.rb',
+  '_test.rb',
+];
+
+/**
+ * Case-sensitive `Test`/`Tests`/`Spec` suffixes. Lowercasing first would also
+ * match production names such as `Contest.swift` and `Latest.php`.
+ */
+const TEST_PATH_CASED_SUFFIXES: readonly string[] = [
+  'Tests.swift',
+  'Test.swift',
+  'Tests.cs',
+  'Test.cs',
+  'Test.php',
+  'Spec.php',
+];
+
+/** Absent / empty paths are not test paths. */
+export function isTestFilePath(filePath: string | null | undefined): boolean {
+  if (!filePath) return false;
+  const slashed = filePath.replace(/\\/g, '/');
+  const prefixed = slashed.startsWith('/') ? slashed : `/${slashed}`;
+  const lower = prefixed.toLowerCase();
+  if (TEST_PATH_SUBSTRINGS.some((needle) => lower.includes(needle))) return true;
+  if (TEST_PATH_DELIMITED_SUFFIXES.some((suffix) => lower.endsWith(suffix))) return true;
+  // Xcode `{Product}UITests` targets. Slash-anchored `/uitests/` does not match
+  // `MyAppUITests`; an unanchored `uitests/` substring also matches `fruitests`.
+  if (prefixed.split('/').some((seg) => seg.endsWith('UITests'))) return true;
+  const basename = prefixed.slice(prefixed.lastIndexOf('/') + 1);
+  return TEST_PATH_CASED_SUFFIXES.some((suffix) => basename.endsWith(suffix));
+}
diff --git a/gitnexus/src/mcp/local/local-backend.ts b/gitnexus/src/mcp/local/local-backend.ts
index fa5170ae2..1480b0843 100644
--- a/gitnexus/src/mcp/local/local-backend.ts
+++ b/gitnexus/src/mcp/local/local-backend.ts
@@ -29,6 +29,7 @@ import { LBUG_ID_PROBE_BATCH_SIZE, LBUG_QUERY_BATCH_SIZE } from '../../core/lbug
 import { chunk, mapConcurrent } from '../../lib/utils.js';
 import { pathSuffixOf } from './path-predicate.js';
 import { toOneBasedLine } from '../../core/ingestion/utils/line-base.js';
+import { isTestFilePath } from '../../core/ingestion/utils/test-file-path.js';
 import { isWalCorruptionError, WAL_RECOVERY_SUGGESTION } from '../../core/lbug/lbug-config.js';
 // Embedding imports are lazy (dynamic import) to avoid loading onnxruntime-node
 // at MCP server startup — crashes on unsupported Node ABI versions (#89)
@@ -313,31 +314,8 @@ function normalizeToolParams(
 // AI context generation is CLI-only (gitnexus analyze)
 // import { generateAIContextFiles } from '../../cli/ai-context.js';
 
-/**
- * Quick test-file detection for filtering impact results.
- * Matches common test file patterns across all supported languages.
- */
-export function isTestFilePath(filePath: string | null | undefined): boolean {
-  if (!filePath) return false;
-  const p = filePath.toLowerCase().replace(/\\/g, '/');
-  return (
-    p.includes('.test.') ||
-    p.includes('.spec.') ||
-    p.includes('__tests__/') ||
-    p.includes('__mocks__/') ||
-    p.includes('/test/') ||
-    p.includes('/tests/') ||
-    p.includes('/testing/') ||
-    p.includes('/fixtures/') ||
-    p.endsWith('_test.go') ||
-    p.endsWith('_test.py') ||
-    p.endsWith('_spec.rb') ||
-    p.endsWith('_test.rb') ||
-    p.includes('/spec/') ||
-    p.includes('/test_') ||
-    p.includes('/conftest.')
-  );
-}
+/** Shared predicate; re-exported so MCP importers keep the old public name. */
+export { isTestFilePath };
 
 /** Valid LadybugDB node labels for safe Cypher query construction */
 export const VALID_NODE_LABELS = new Set([
diff --git a/gitnexus/test/unit/test-file-path.test.ts b/gitnexus/test/unit/test-file-path.test.ts
new file mode 100644
index 000000000..a4ffc71bd
--- /dev/null
+++ b/gitnexus/test/unit/test-file-path.test.ts
@@ -0,0 +1,106 @@
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'node:fs';
+import { isTestFilePath } from '../../src/core/ingestion/utils/test-file-path.js';
+import { isTestFile } from '../../src/core/ingestion/entry-point-scoring.js';
+import { isTestFilePath as backendIsTestFilePath } from '../../src/mcp/local/local-backend.js';
+
+describe('isTestFilePath — shared predicate', () => {
+  it('returns false for nullish input rather than throwing', () => {
+    expect(isTestFilePath(undefined)).toBe(false);
+    expect(isTestFilePath(null)).toBe(false);
+    expect(isTestFilePath('')).toBe(false);
+  });
+
+  it('normalizes Windows separators and casing', () => {
+    expect(isTestFilePath('SRC\\Test\\FooTests.cs')).toBe(true);
+    expect(isTestFilePath('pkg\\thing_test.go')).toBe(true);
+    expect(isTestFilePath('src\\Widgets.Tests\\WidgetTests.cs')).toBe(true);
+  });
+
+  // These were recognized by entry-point scoring but NOT by the MCP copy, so
+  // `includeTests: false` silently failed to filter them.
+  for (const p of [
+    'app/src/test/java/com/x/FooTest.java',
+    'ios/MyAppTests/LoginTests.swift',
+    'ios/MyAppUITests/FlowTest.swift',
+    'ios/MyAppUITests/Flow.swift',
+    'ios/MyAppUITests/README.swift',
+    'src/Widgets.Tests/WidgetTests.cs',
+    'src/Widgets.UnitTests/Thing.cs',
+    'src/Widgets.IntegrationTests/Thing.cs',
+    'tests/Feature/LoginTest.php',
+    'tests/Unit/ThingSpec.php',
+    'tests/Feature/Support/FakeGateway.php',
+  ]) {
+    it(`detects a test path the MCP copy used to miss: ${p}`, () => {
+      expect(isTestFilePath(p)).toBe(true);
+    });
+  }
+
+  // These were recognized by the MCP copy but NOT by entry-point scoring, so
+  // they could be selected as process entry points.
+  for (const p of ['tests/fixtures/sample.py', 'tests/conftest.py']) {
+    it(`detects a test path entry-point scoring used to miss: ${p}`, () => {
+      expect(isTestFilePath(p)).toBe(true);
+    });
+  }
+
+  for (const p of [
+    'src/app/widgets.ts',
+    'src/core/ingestion/utils/test-file-path.ts',
+    'pkg/service/handler.go',
+    'app/models/user.rb',
+    'Contest.swift',
+    'Contest.cs',
+    'Protest.cs',
+    'Latest.php',
+    'src/fixtures/schema.ts',
+    'src/fruitests/helpers.swift',
+  ]) {
+    it(`does not classify production code as test: ${p}`, () => {
+      expect(isTestFilePath(p)).toBe(false);
+    });
+  }
+});
+
+describe('test-file classification has exactly one implementation', () => {
+  // Regression guard: two hand-maintained copies drifted apart once already.
+  // Both public names must delegate to the same predicate.
+  const paths = [
+    'src/app/widgets.ts',
+    'app/src/test/java/com/x/FooTest.java',
+    'ios/MyAppTests/LoginTests.swift',
+    'src/Widgets.Tests/WidgetTests.cs',
+    'tests/conftest.py',
+    'tests/fixtures/sample.py',
+    'src/fixtures/schema.ts',
+    'Contest.swift',
+    'spec/models/user_spec.rb',
+    'pkg/thing_test.go',
+    'tests/Feature/LoginTest.php',
+  ];
+
+  it('entry-point-scoring isTestFile agrees with the shared predicate', () => {
+    for (const p of paths) expect(isTestFile(p)).toBe(isTestFilePath(p));
+  });
+
+  it('local-backend isTestFilePath agrees with the shared predicate', () => {
+    for (const p of paths) expect(backendIsTestFilePath(p)).toBe(isTestFilePath(p));
+  });
+});
+
+describe('shared predicate stays dependency-free', () => {
+  // Poka-yoke for #2802: `local-backend.ts` imports this module, so anything
+  // imported here lands in MCP server startup. The duplication this module
+  // replaced existed precisely because `entry-point-scoring.ts` pulls in the
+  // language-provider registry. An import added here would silently reintroduce
+  // that startup cost.
+  it('declares no imports', () => {
+    const src = readFileSync(
+      new URL('../../src/core/ingestion/utils/test-file-path.ts', import.meta.url),
+      'utf8',
+    );
+    const imports = src.split('\n').filter((l) => /^\s*(import\b|export\s.*\sfrom\s)/.test(l));
+    expect(imports).toEqual([]);
+  });
+});