[salma2vec]

What and why

Closes #305

In reward mode, RunContainerUnitTestsVerifierTaskStep docker cp'd reward_path out of the task container after the verifier command ran, and scored whatever it found. Nothing removed the file first. An agent working in that container could write 1 to the reward path during its turn. If test.sh then exited without writing a reward, the planted file was recorded as score=1.0, result=True for a failed run. That covers a set -e script, or pytest && echo 1 > reward.txt, which relies on "missing file = 0".

This PR removes every entry in result_paths (which includes reward_path) inside the container right before the main command. Anything extracted afterwards was written by this verifier run.

• The removal runs as docker exec -u root -w / … rm -f -- <paths> via exec_script, so it fails loudly. Root ensures an agent-owned file can be removed. -w / resolves a relative path the same way the later docker cp does.
• It runs after setup_commands, so a setup step can't leave a stale result behind either. A retried step also no longer reads a previous attempt's file.
• Exit-code semantics are unchanged. A test.sh that writes a partial reward and exits non-zero is still graded by that reward. I corrected the step-9 comment, which said a non-zero exit is "already recorded as score 0": that only happens when no reward file exists.

How it was tested

• New test_reward_comes_from_this_verifier_run, parametrized: correct answer, wrong answer, and wrong answer with a planted /logs/verifier/reward.txt. It drives execute() against a fake sandbox that models the container's files: rm -f and docker cp act on them, and the verifier command writes the reward only when the answer is right. On main the planted case scores 1.0 and fails the test. With this change it scores 0.0. The other two cases pass on both.
• pytest tst/unit packages/agentenv-protocol/tests -n 4: 9455 passed, 49 skipped. 16 failed and 119 errored, all in tst/unit/store/aws/*, store/google_transport_test.py and gcp_secret_manager_secret_store_test.py (SocketBlockedError, no local emulators here). The identical set fails on main.
• ruff check is clean on both files.

Found and fixed with Claude Code. The runs above were executed locally.

🤖 Generated with Claude Code

Confidence Score: 5/5

The PR appears safe to merge; no blocking issues were found.

Summary

Clears reward_path before the verifier command runs, without deleting other requested result files.

• Reward-mode verifiers start each run with a clear reward file.

_{Reviews (2) · Last reviewed commit: "fix(verifier): clear only the reward fil..." · Reviewed by Greptile}

[jimmy-holdout]

Thanks for adding the cleanup; the pre-written reward case from #305 now scores 0. Two concerns:

1. The cleanup removes every result_paths entry, not just reward_path. A task that declares an agent-produced file (e.g. /app/answer.txt) as a result path now loses it before the verifier reads it, so a correct answer scores 0 and the step raises. Limiting the removal to reward_path avoids that.
2. The removal happens once, before the verifier runs, while the task container is still live, so anything still running there can write the file again. Reading the reward from a location only the verifier can write, or stopping the task's processes before verification, would be more robust.

Happy to share the test cases.

[earakely-scale]

I pushed a3b7365 on top of 58a6c2f with three changes from review:

• Only reward_path is cleared. Clearing every result_paths entry breaks steps that extract a file an earlier step's job wrote:
  • Prod already relies on this. 33 tasks (about 4,200 verifier steps) have a supervisor step that starts or adopts a long-running engine and hands off every 390 s. The engine, not the step's command, writes /work/events.tail.json, so deleting it before each step made a hand-off step extract nothing.
  • The reward file is enough. The score is read only from reward_path, so clearing that file still closes Reward-mode container verifier scores a reward.txt the agent planted, even when test.sh exits non-zero #305. Every reward-mode step in prod writes its reward from its own command, so clearing it breaks none of them.
• The comment claims only what the clearing gives: a process the agent left running can still write the reward while the command runs.
• docker exec -u 0 instead of -u root, which fails with "unable to find user root" in an image with no passwd entry for root.

Verified on an agent-environments-admin VM (m5.2xlarge, linux/amd64), with real Docker, on three trees:

Check	main	58a6c2f	a3b7365
Real Claude Code (claude-haiku-5-5) in the task container writes 1 to the reward file, then tests that fail without writing one	scored 1.0 (#305)	the step that reads the planted file has it deleted first, and fails	scored 0, local and modal_vm
Engine hand-off: segment 1 starts an engine that writes its tail once, segment 2 adopts it	tail extracted	tail deleted, so a later step finds none	tail extracted
No passwd entry for root, verifier as uid 0, planted reward	scored 1.0	step errors (-u root)	scored 0
test_verify_sandbox_local.py, 3 new tests (one per row above)	2 fail	2 fail	10/10 pass
Unit tests: tst/unit/task_step/verifiers (405), full unit tier (9,097)			pass

[jimmy-holdout]

Thanks for the quick turnaround. I re-ran the cases from #305 against main after the merge (Ubuntu, network off): a pre-written reward now scores 0 with both the fail-fast and the pass-only verifier scripts, correct answers still score 1, and an answer declared as an extra result path is extracted and scores 1 again. The note about a process still running in the container matches what I see.