fix(sandboxes): bound background output retrieval - #862
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August 24, 2026 17:49
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…tput-burst # Conflicts: # packages/prime-sandboxes/tests/test_batch_status.py
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Caps background-job output reads at 20 concurrent requests, retrieves stdout/stderr
sequentially, preserves completed exit codes when output retrieval fails, adds jittered retries and
errno diagnostics, and includes a 100-job concurrency test.
Verification:
Note
Medium Risk
Large change to background-job polling, concurrency, and client shutdown/delete ordering; behavior is well-tested but affects hot paths for VM batch job monitoring.
Overview
VM background jobs now separate completion checks from stdout/stderr downloads. New
get_background_job_status/get_background_job_statusesreturnBackgroundJobStatusSnapshotwithout touching log files;get_background_jobandget_background_jobsstill hydrate tails but route output through a shared coordinator.Output hydration is deduplicated per job, cached in a byte-bounded LRU, and limited client-wide (defaults: 20 active, 200 queued, 64 MiB cache) via
background_job_output_concurrency,background_job_output_queue_size, andbackground_job_output_cache_byteson sync/async clients. Fetches are fair across sandboxes, sequential per job (stdout then stderr), and respect a bounded retrieval deadline after the exit file is seen.Reliability:
BackgroundJobStatusgainsstdout_error/stderr_errorso a known exit code stays authoritative when a stream is missing; read retries use jittered backoff and richer errno diagnostics. Sandbox delete/drain cancels queued output work and coordinates with the expanded operation lease registry before API teardown.Reviewed by Cursor Bugbot for commit 63425e7. Bugbot is set up for automated code reviews on this repo. Configure here.