[loopx-agent]

Problem

The return worker captured one timestamp at the start of each drain. A provider verification that finished later could produce a delivery receipt with delivered_at set to the start of the drain.

Change

Keep one cutoff for scanning eligible returns and read the clock again for each delivery transaction. Callers supplying now still get a fixed clock. The restart recovery test verifies the completion time and keeps the assertion that the provider is not sent a second reply.

Validation

• The new assertion fails on the base commit when provider verification advances the clock by seven seconds.
• python -m pytest -q tests/test_manager_context_roundtrip.py passed all 118 tests on the fix.
• git diff --check passed.