[SaladDay]

Adds example/rl-eval/, a single Python script that uses the public /v1 Agents API as a rollout engine for RL and evaluation.

Each rollout is one hosted Session with network disabled: the task files go in as inline initial files, the instruction as input, and the answer comes back as the Artifact /workspace/outputs/answer.json. The script grades it outside the sandbox (expected.json never enters it), records the Items and Turn usage, deletes the Session, and appends one JSONL row per rollout. It runs a Harness × model × K-sample matrix in parallel, handles timeouts by cancelling the Turn, and prints mean reward and pass@k. --model-base-url with {rollout_id} points rollouts at a training-side inference server, which is where token ids and logprobs are recorded.

Five bundled tasks (CSV aggregation, log counting, a small bug fix, nested JSON, SQLite) need only the managed sandbox image. Tasks graded inside their own container (SWE-bench, Terminal-Bench) need self_hosted and are out of scope.

Also:

• docs/examples.md (+ zh) gets an "RL and evaluation rollouts" section; CONTRIBUTING.md names the example's owner and boundary.
• make check-example runs the example's unit tests; scripts/ci_plan.py routes .py/.sh under example/ to the example job.

Verification

• python3 example/rl-eval/rl_eval_test.py: 9 tests pass (grading, pass@k, summary, task loading).
• scripts/ci_plan_test.py and core-distribution-manifest.test.py BundledDocsTests pass.
• Every expected answer was recomputed independently from the task files.
• Live runs on a test deployment (microsandbox nodes, MiniMax-M2.7):
  • --harness codex --harness claude_sdk --samples 2: 20/20 rollouts completed with reward 1.0 (table in the README).
  • --harness claude_sdk --model MiniMax-M2.7 --model-base-url … --model-protocol anthropic: 5/5 with reward 1.0 through the per-rollout provider path.
  • --timeout 8: the rollout is recorded as timeout with its usage and Items; the Turn is cancelled and the Session deleted.
  • mcode on that deployment is rejected at create (NFS workspace storage needs retained native history); each rollout is recorded as error and the batch continues.
  • No Session was left in the Project after the runs.

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