Python 3.10: Deep Scan deadline and coordinator leases fail on Z-suffixed timestamps

[mldangelo-oai]

Summary

Codex Security documents Python 3.10 support, but Deep Scan passes timestamps ending in Z directly to datetime.fromisoformat. Python 3.10 rejects that format, so deadline checks and coordinator-lease recovery can raise ValueError.

Affected code

• The workbench timestamp producer emits UTC timestamps ending in Z.
• Deep Scan deadline checks parse those timestamps without normalization.
• Both coordinator-lease paths do the same for stored timestamps and heartbeats.

Reproduction

The current functions were invoked against synthetic in-memory SQLite state with a parser shim that rejects trailing Z, matching Python 3.10 behavior:

deep_scan_deadline_reached: ValueError: Invalid isoformat string
coordinator_lease_is_live, generation 1: ValueError: Invalid isoformat string
coordinator_lease_is_live, generation 2: ValueError: Invalid isoformat string

This reproduces the Python 3.10 parsing behavior against the current modules. A native Python 3.10 interpreter was not available for this check.

Expected behavior

Normalize trailing Z or z to +00:00 in a shared timestamp parser, and cover deadline checks plus both coordinator-lease paths with Python 3.10 regression tests.

Related: #35 and #205 cover a separate remediation-claim parser and do not address these Deep Scan call sites.