Closes#24091
Adds
`TestDeleteChatDebugDataAfterMessageIDStepLevelFieldBoundariesAndNulls`,
which complements the existing triggered-runs test for
`DeleteChatDebugDataAfterMessageID` with boundary and NULL coverage for
step-level message IDs.
The existing
`TestDeleteChatDebugDataAfterMessageIDIncludesTriggeredRuns` already
exercises the `step.assistant_message_id > @message_id` deletion path.
This test focuses on:
- Strict greater-than behavior at the cutoff for assistant and
history-tip step message IDs.
- Step-level assistant and history-tip message ID combinations.
- SQL NULL behavior for step-level message IDs.
- A mixed-step run where one matching step deletes the whole run and
cascades every step.
| Scenario | assistant_message_id | history_tip_message_id | Expected |
|----------|----------------------|------------------------|----------|
| Assistant above cutoff, history tip NULL | cutoff + 5 | NULL | Deleted
|
| Assistant above cutoff, history tip below cutoff | cutoff + 20 |
cutoff - 3 | Deleted |
| Assistant below cutoff, history tip NULL | cutoff - 3 | NULL |
Preserved |
| Assistant at cutoff boundary, history tip NULL | cutoff | NULL |
Preserved |
| Assistant NULL, history tip above cutoff | NULL | cutoff + 2 | Deleted
|
| Assistant NULL, history tip at cutoff boundary | NULL | cutoff |
Preserved |
| Both step message IDs NULL | NULL | NULL | Preserved |
> Generated by Coder Agents
<details><summary>Review notes</summary>
- Run-level message IDs are below the cutoff to isolate step-level
selection.
- The assistant-above-cutoff scenario includes a second nonmatching step
to cover mixed-step deletion.
- The test uses unique model and chat names for isolation.
- `go test -v ./coderd/database -run
TestDeleteChatDebugDataAfterMessageID -count=1` passes.
</details>