[Kayvan-Zahiri]

Sync and async Job.stream() keep polling after the API returns CANCELLED because FINAL_STATES omits that status. is_completed() already considers it terminal, so status/output polling and stream polling disagree. A cancelled run_sync response also falls through to unnecessary status fetching.

Add CANCELLED to the shared terminal states and have is_completed() use that same list. Streams still yield a final buffered chunk before stopping on the subsequent empty terminal response.

Usage:

job = endpoint.run({"input": {"prompt": "hello"}})
for chunk in job.stream():
    print(chunk)
# The iterator now finishes when the job has been cancelled and its output is drained.

The same behavior applies to async for chunk in job.stream().

Validation:

• Added 17 regression/control cases: both stream APIs across all four terminal states, with/without buffered output, plus run_sync returning a cancelled response without further polling.
• Before the fix: the 4 cancellation stream cases fail; all 12 other stream controls pass. The added run_sync check also exposes the fall-through.
• All 66 endpoint tests pass; all 17 new cases pass after final formatting.
• Black formatting and git diff --check pass.
• Focused test invocation uses -o addopts='' because the repository-wide 90% coverage threshold is not meaningful for an endpoint-only run. The initial invocation passed its tests but failed that global coverage gate. Full repository coverage is not claimed.
• No Runpod API calls, GPU provisioning, or live polling. Tests use fake clients and mocked sleeps.

AI assistance: Codex independently investigated, reproduced, implemented, and tested this fix with the account owner's authorization. Draft for maintainer review; no human implementation review yet.