diff --git a/.needle-predispatch-sha b/.needle-predispatch-sha
index ee46070..7f402ec 100644
--- a/.needle-predispatch-sha
+++ b/.needle-predispatch-sha
@@ -1 +1 @@
-30e02437ed27b17cba89afb74f72753939f44e37
+5fbd5a682372981ecaad8b473280dbbab685df12
diff --git a/notes/pdftract-2zw.md b/notes/pdftract-2zw.md
index f4702a2..97378b0 100644
--- a/notes/pdftract-2zw.md
+++ b/notes/pdftract-2zw.md
@@ -23,7 +23,7 @@ Each fixture includes:
 
 ### 2. Integration Tests
 
-Created `crates/pdftract-core/tests/page_classification.rs` with 4 tests:
+Created `crates/pdftract-core/tests/page_classification.rs` with 5 tests:
 
 1. **test_page_classification_fixtures**: Validates all fixtures classify correctly
    - Checks class matches expected
@@ -43,6 +43,10 @@ Created `crates/pdftract-core/tests/page_classification.rs` with 4 tests:
    - Checks confidence_min in [0.0, 1.0]
    - Validates class names
 
+5. **test_reproducibility_gate_with_perturbation**: Verifies reproducibility gate fails on perturbation
+   - Intentionally perturbs a confidence value
+   - Asserts the reproducibility check fails with clear diff
+
 ### 3. CI Integration
 
 The tests are automatically run in CI via the Argo Workflows pipeline:
@@ -56,20 +60,22 @@ The tests are automatically run in CI via the Argo Workflows pipeline:
 | Criterion | Status | Notes |
 |-----------|--------|-------|
 | 4 fixtures present | ✅ PASS | vector_pure, scanned_single, brokenvector_pdfa, hybrid_header_body |
-| cargo test passes | ✅ PASS | 4/4 tests passing |
-| Reproducibility gate | ✅ PASS | test_page_classification_reproducibility verifies byte-identical JSON |
+| cargo test passes | ✅ PASS | 5/5 tests passing |
+| Reproducibility gate | ✅ PASS | test_page_classification_reproducibility + test_reproducibility_gate_with_perturbation |
 | Fixtures < 1 MB | ✅ PASS | Total: 3.6 KB |
+| Gate fails on perturbation | ✅ PASS | test_reproducibility_gate_with_perturbation verifies this |
 
 ## Test Output
 
 ```
-running 4 tests
+running 5 tests
 test test_expected_json_validity ... ok
 test test_fixture_files_exist_and_size ... ok
 test test_page_classification_fixtures ... ok
 test test_page_classification_reproducibility ... ok
+test test_reproducibility_gate_with_perturbation ... ok
 
-test result: ok. 4 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
+test result: ok. 5 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
 ```
 
 ## References