fix: update DESIGN.md snapshot restore flow to reflect post-resume MMDS ordering#413
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claude-claude[bot] wants to merge 2 commits intofix-output-pipeline-restorefrom
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fix: update DESIGN.md snapshot restore flow to reflect post-resume MMDS ordering#413claude-claude[bot] wants to merge 2 commits intofix-output-pipeline-restorefrom
claude-claude[bot] wants to merge 2 commits intofix-output-pipeline-restorefrom
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Three bugs caused container stdout to not reach the host after snapshot restore: 1. put_mmds before VM resume: Firecracker accepts PUT /mmds while the VM is paused but the guest-visible data isn't updated. fc-agent never sees the new restore-epoch so it never reconnects. Fix: move put_mmds after resume. 2. Unconditional notify_one: cmd_snapshot_run fired output_reconnect.notify_one() for all snapshot types. For pre-start snapshots (container not yet running), the listener has no dead connection to drop. The stored Notify permit poisons the first real connection by immediately triggering the reconnect branch in select!, dropping a valid connection. Fix: only notify for startup snapshots. 3. Listener stuck on stale connection: fc-agent reconnects multiple times during snapshot create/restore cycles. Each reconnect creates a new vsock connection queued in the listener's accept backlog. The listener accepted the FIRST connection and blocked on read_line, while fc-agent wrote to the LATEST connection. Fix: race read_line against listener.accept() in tokio::select!, always switching to the newest connection. Also adds output verification to test_heavy_output_after_snapshot_restore to catch this class of bug — the test previously only checked health and exec, not that container output actually reached the host.
…DS ordering
Move "Update MMDS with new config" from Identity Patching (step 3) to a
new step 6 after Resume VM (step 5), matching the code change in
restore_from_snapshot() where put_mmds was moved after patch_vm_state("Resumed").
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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Auto-Fix for PR #412
Issues Fixed
Changes
DESIGN.md: Moved "Update MMDS with new config" from the Identity Patching bullet list to a new step 6 after "Resume VM" (step 5), with an explanatory note that guest-visible MMDS data isn't updated until the VM is running.Generated by Claude | Review Run