[waleedlatif1]

Summary

• Task-mode setTimeout/setInterval bridges in the isolated-vm worker kept a Node Timeout, a Map entry, and an ivm.Reference per call on the shared worker heap with no count limit — outside the isolate's 128 MB memoryLimit. One document-generation or workflow-test script could grow worker RSS without bound or starve the worker's event loop for every co-tenant execution on it
• Cap each task execution at 1000 pending timers and 50 active intervals; the bridge throws a RangeError back into the isolate (no host frames in the stack) and releases the callback reference
• On host timeout, send the existing cancel IPC to the worker. A never-settling promise escapes isolated-vm's script timeout, so the worker kept the isolate (and its live intervals) running until the worker retired — on both the task and Function-block paths
• Skipped the suggested interval period floor and firing-count cap: zero-delay setTimeout chains already reach the same rate, so the floor only changes behavior for legitimate setInterval(fn, 1) callers

Type of Change

• Bug fix (security)

Testing

Verified against the real worker process before and after (scratch harness that forks isolated-vm-worker.cjs over IPC):

• Before: for (...) setTimeout(f, 60000) grew worker RSS ~80 MB/s, past 2.5 GB at 30s, well beyond the script timeout. 20k setInterval(f, 1) starved the worker — 20 trivial co-tenant executions did not finish within 60s
• After: the flood stops at the cap in <100ms; co-tenant latency median 4ms / max 6ms under the interval flood, 3ms / 3ms under the worst load the caps allow (1000 zero-delay chains + 50 intervals), same as idle
• Hung task with a busy interval, local pool: worker CPU in the 3s after timeout went from 2060ms to 0ms; the worker keeps serving
• Reverted each guard separately (timeout cap, interval cap, interval decrement on clear) and watched its case go red
• Real docx-generate (2000 paragraphs), pptx-generate (200 slides, JSZip setImmediate chains), pdf-generate (200 pages) through runSandboxTask: valid output, timings unchanged vs staging
• New isolated-vm.test.ts case (host sends cancel on timeout) red before / green after; isolated-vm.test.ts + isolated-vm-worker-hardening.test.ts 28/28
• test-isolated-vm-remote-e2e.ts: new check "caps the timers a task may hold on the shared worker"; all 21 checks pass, new check fails on the staging worker
• biome, check:test-patterns, check:comment-hygiene, check:utils, check:boundaries; full gate left to CI

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing (new tests pass the test-audit authoring gate)
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated
docs	Skipped		Nov 7, 2026 8:24pm UTC

[cubic-dev-ai]

No issues found across 4 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Turn on auto-fix | Re-trigger cubic}

[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge; no new actionable issues were found.

Summary

The PR caps task timers and asks the worker to stop an execution when the host timeout fires.

• Each task stops at 1,000 pending timers or 50 active intervals.
• Host timeouts now ask the worker to dispose the timed-out isolate.

_{Reviews (2) · Last reviewed commit: "improvement(sandbox): cover interval reu..." · Reviewed by Greptile}

[waleedlatif1]

@greptile

[waleedlatif1]

@cubic-dev-ai review this PR

[cubic-dev-ai]

@cubic-dev-ai review this PR

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[cubic-dev-ai]

No issues found across 4 files

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

_{Turn on auto-fix | Re-trigger cubic}