diff --git a/CHANGELOG.md b/CHANGELOG.md
index c9f15c8331..40beb591d3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -233,6 +233,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 #### Symbols, tests and the viewer
 
+- Java packages named `build` under standard main and test source roots are now indexed without pulling Gradle or Maven build output into the graph. (#1642)
 - Kotlin functions and methods now carry their signature — `(params): ReturnType` — in `codegraph_explore`, `node` and the viewer, instead of no signature at all. Re-index Kotlin projects after upgrading. (#1495)
 - `codegraph affected` now finds Go, Python and JVM test files that previously went unreported, while preserving custom `--filter` behavior (thanks @danusha2345; #1507, #1688).
 
diff --git a/__tests__/extraction.test.ts b/__tests__/extraction.test.ts
index 16e0fc2449..8fd91d7dd7 100644
--- a/__tests__/extraction.test.ts
+++ b/__tests__/extraction.test.ts
@@ -8188,6 +8188,39 @@ describe('Nested non-submodule git repos', () => {
     expect(ig.ignores('src/app.ts')).toBe(false);
   });
 
+  it('keeps Java packages named build while excluding build output (#1642)', () => {
+    const sourceFile = 'module/src/main/java/com/acme/build/RealtimePlusService.java';
+    const testFile = 'module/src/test/java/com/acme/build/RealtimePlusServiceTest.java';
+    const outputFile = 'module/build/generated/Generated.java';
+
+    for (const rel of [sourceFile, testFile, outputFile]) {
+      const abs = path.join(tempDir, rel);
+      fs.mkdirSync(path.dirname(abs), { recursive: true });
+      fs.writeFileSync(abs, 'class Example {}\n');
+    }
+
+    const scope = buildScopeIgnore(tempDir);
+    expect(scope.ignores(sourceFile)).toBe(false);
+    expect(scope.ignores(testFile)).toBe(false);
+    expect(scope.ignores(outputFile)).toBe(true);
+
+    const files = scanDirectory(tempDir);
+    expect(files).toContain(sourceFile);
+    expect(files).toContain(testFile);
+    expect(files).not.toContain(outputFile);
+  });
+
+  it('lets an explicit .gitignore exclude a Java package named build (#1642)', () => {
+    const sourceFile = 'src/main/java/com/acme/build/Hidden.java';
+    const abs = path.join(tempDir, sourceFile);
+    fs.mkdirSync(path.dirname(abs), { recursive: true });
+    fs.writeFileSync(abs, 'class Hidden {}\n');
+    fs.writeFileSync(path.join(tempDir, '.gitignore'), 'src/main/java/**/build/\n');
+
+    expect(buildScopeIgnore(tempDir).ignores(sourceFile)).toBe(true);
+    expect(scanDirectory(tempDir)).not.toContain(sourceFile);
+  });
+
   it('buildDefaultIgnore honors .git/info/exclude (#1728)', async () => {
     const { execFileSync } = await import('child_process');
     const git = (cwd: string, ...args: string[]) =>
diff --git a/src/extraction/index.ts b/src/extraction/index.ts
index 8095ee5b58..94d22308d0 100644
--- a/src/extraction/index.ts
+++ b/src/extraction/index.ts
@@ -237,6 +237,12 @@ const DEFAULT_IGNORE_PATTERNS: string[] = [
   'bazel-*/',        // Bazel output symlink trees
   // Android resource dirs at any depth, with their qualifier variants (#1047).
   ...ANDROID_RES_TYPES.map((t) => `**/res/${t}*/`),
+  // `build` is also a legal Java package segment. Keep it under conventional
+  // Java source roots while continuing to exclude module/build output (#1642).
+  '!**/src/main/java/**/build/',
+  '!**/src/main/java/**/build/**',
+  '!**/src/test/java/**/build/',
+  '!**/src/test/java/**/build/**',
 ];
 
 /** True if `buf` decodes as strict UTF-8 (no invalid byte sequences). */