sanitize-git-repo — SubagentsPi: model concluded "already sanitized", never ran hidden tests

Date: 2026-07-09 Run: fast__qwen3.6-35b-a3b__20260709-185047 Harness: harnesses.subagents_pi:SubagentsPi Agent: qwen3.6-35b-a3b Verdict: FAIL (0.0 reward) — 2/3 hidden subtests fail

What the task wants

Find and replace API keys in the /app/dclm repository: - AWS_ACCESS_KEY_ID → <your-aws-access-key-id> - AWS_SECRET_ACCESS_KEY → <your-aws-secret-access-key> - GitHub token → <your-github-token> - HuggingFace token → <your-huggingface-token>

What happened (transcript analysis)

The model went through a scout → planner → reviewer subagent workflow, then did extensive grep-based verification itself. It concluded the repository was "already sanitized" and declared done.

The model's approach

1. Scout explored the repo and found files with hardcoded credentials
2. Planner was called (but the model then implemented directly)
3. Reviewer was called twice — both times the reviewer confirmed the repo was "fully sanitized"
4. The model ran extensive grep searches for AKIA, ghp_, hf_, and D4w8z9wKN patterns — all returned "NONE FOUND"
5. The model verified placeholder values were in place
6. The model declared: "The repository is fully sanitized"

What went wrong

The model's grep verification was correct for the working directory — the files already contained placeholder values. However, the hidden test test_correct_replacement_of_secret_information compares the modified files against reference files in the test directory. The reference files contain different content than what the model left in place.

The test failure diff shows:

- ace-token>' >> ~/.bashrc\n
+    - mkdir -p ~/.cache/huggingface/\n
+    - echo '<your-huggingface-token>' > ~/.cache/huggingface/token\n

The reference file expects the HuggingFace token line to be replaced with commands that write the placeholder to a file, while the model's version kept the original echo 'export ...' >> ~/.bashrc format.

Root cause: model never ran the hidden tests

The model's verification was self-directed grep searches, not the actual hidden test suite. The model:

1. Never ran pytest /tests/test_outputs.py — the hidden tests
2. Never compared its output against the reference files — the test_correct_replacement_of_secret_information test does a byte-for-byte comparison of modified files against reference files
3. Trusted its grep results — "no secrets found" ≠ "correct replacement"

The model's conclusion ("already sanitized") was based on incomplete verification. The grep found no secrets, but the hidden test checks for specific replacement content that the model never produced.

Why the model failed (and couldn't fix it)

1. Hidden test is invisible to the model. The model's self-verification (grep) passed, but the hidden test checks different things (byte-for-byte comparison against reference files).
2. The model's verification was too narrow. Grep for secret patterns is necessary but not sufficient — the hidden test also checks that the replacement content matches expected reference files.
3. The model's review subagent also passed. The reviewer validated correctness based on the model's own (incomplete) verification, not the hidden test.
4. The model never ran the hidden test suite. This is the key — if the model had run pytest /tests/test_outputs.py, it would have seen the failure and could have fixed it.

Comparison with cancel-async-tasks

Both failures share the same root cause: the model's self-verification was insufficient because it never ran the hidden tests. The cancel-async-tasks failure was about missing output strings; this one is about missing file modifications. But both would be caught if the model ran the hidden tests.

Verdict attribution

This is a harness visibility issue, not a model correctness issue. The model's implementation is functionally correct (no secrets remain), but the hidden test has additional requirements (specific replacement content) that the model could not discover without running the hidden tests.