diff --git a/graphify/detect.py b/graphify/detect.py
index d5521b3..d5811ad 100644
--- a/graphify/detect.py
+++ b/graphify/detect.py
@@ -370,6 +370,12 @@ _SKIP_DIRS = {
     ".pytest_cache", ".mypy_cache", ".ruff_cache",
     ".tox", ".eggs", "*.egg-info",
     "graphify-out",  # never treat own output as source input (#524)
+    # Coverage/test-artefact dirs — generated, never architecturally meaningful
+    "coverage", "lcov-report",              # Vitest/Istanbul/nyc HTML reports (#870)
+    "visual-tests", "visual-test",          # Playwright/visual-regression bundles (#869)
+    "__snapshots__", "snapshots",           # Jest/Vitest snapshot dirs
+    "storybook-static",                     # Storybook production build output
+    "dist-protected",                       # Protected dist variants (same noise as dist)
 }
 
 # Large generated files that are never useful to extract
diff --git a/tests/test_detect.py b/tests/test_detect.py
index c1754a7..740d1e4 100644
--- a/tests/test_detect.py
+++ b/tests/test_detect.py
@@ -316,3 +316,54 @@ def test_detect_video_not_in_words(tmp_path):
     result = detect(tmp_path)
     # Only video file present — total_words should be 0
     assert result["total_words"] == 0
+
+
+def test_detect_skips_coverage_dir(tmp_path):
+    """coverage/ and lcov-report/ are noise dirs — HTML reports inside must be excluded (#870)."""
+    cov = tmp_path / "coverage" / "lcov-report"
+    cov.mkdir(parents=True)
+    (cov / "index.html").write_text("<html>coverage report</html>")
+    (cov / "src.ts.html").write_text("<html>file coverage</html>")
+    (tmp_path / "main.py").write_text("def hello(): pass")
+    result = detect(tmp_path)
+    all_files = [f for files in result["files"].values() for f in files]
+    cov_prefix = str(tmp_path / "coverage")
+    assert not any(f.startswith(cov_prefix) for f in all_files)
+    assert any("main.py" in f for f in all_files)
+
+
+def test_detect_skips_visual_tests_dir(tmp_path):
+    """visual-tests/ bundles and snapshots are noise — must be excluded (#869)."""
+    vt = tmp_path / "visual-tests"
+    vt.mkdir()
+    (vt / "bundle.js").write_text("var u3=function(){};var d2=function(){}")
+    (vt / "screens.tsx").write_text("export const Screen = () => <div/>")
+    (tmp_path / "app.py").write_text("def main(): pass")
+    result = detect(tmp_path)
+    all_files = [f for files in result["files"].values() for f in files]
+    assert not any("visual-tests" in f for f in all_files)
+    assert any("app.py" in f for f in all_files)
+
+
+def test_detect_skips_snapshots_dir(tmp_path):
+    """__snapshots__/ and snapshots/ are jest/vitest artefacts — must be excluded."""
+    (tmp_path / "__snapshots__").mkdir()
+    (tmp_path / "__snapshots__" / "app.test.ts.snap").write_text("// Jest Snapshot\nexports[`test 1`] = `<div/>`")
+    (tmp_path / "app.ts").write_text("export function greet() { return 'hi'; }")
+    result = detect(tmp_path)
+    all_files = [f for files in result["files"].values() for f in files]
+    assert not any("__snapshots__" in f for f in all_files)
+    assert any("app.ts" in f for f in all_files)
+
+
+def test_detect_skips_storybook_static_dir(tmp_path):
+    """storybook-static/ is a build artefact — must be excluded."""
+    sb = tmp_path / "storybook-static"
+    sb.mkdir()
+    (sb / "index.html").write_text("<html>storybook</html>")
+    (sb / "main.js").write_text("(function(){var s=1;})()")
+    (tmp_path / "Button.tsx").write_text("export const Button = () => <button/>")
+    result = detect(tmp_path)
+    all_files = [f for files in result["files"].values() for f in files]
+    assert not any("storybook-static" in f for f in all_files)
+    assert any("Button.tsx" in f for f in all_files)