[BUG] Opus 4.7 stale background-job reporting + false-completeness framing + checkpoint-stop reflex (multi-hour autonomous session)

Closing as duplicate of #54682

Same family of failure (Opus 4.7 false completion in long autonomous sessions). #54682 is the more comprehensive existing report and is actively engaged.

The two unique failure modes from this report — stale background-job state reporting and timeline-impossible verification claims — have been added as a comment on #54682 to keep the signal consolidated:

https://github.com/anthropics/claude-code/issues/54682#issuecomment-4359681942

Original report content preserved below for the record.

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Original report

[Original body of #55327 — see https://github.com/anthropics/claude-code/issues/55327 for the full text. Closing in favor of #54682.]