| name | wow-debugging |
| description | Use when Wow commands, events, sourcing, sagas, projections, wait plans, Query DSL, retry policies, starter configuration, or tests fail, hang, skip handlers, produce unexpected state, or behave inconsistently |
Wow Debugging
Find the broken link in the Wow pipeline before fixing code. Guessing at event-sourced systems creates new symptoms because command, event, state, projection, and wait layers are coupled by metadata.
Iron Law
No fix before root cause. Reproduce, locate the failing stage, compare with a working example, then make one minimal change.
Phase 1: Reproduce
- Capture the exact command, test, endpoint, event, or configuration that fails.
- Run the narrowest command that reproduces it.
- Read the full error, stack trace, emitted logs, and failing assertion.
- Check recent diffs before proposing a fix.
Phase 2: Locate the Stage
| Symptom | First Checks |
|---|
| Command not handled | Command route, aggregate metadata, @AggregateRoot, @OnCommand, KSP output, command bus. |
| Aggregate state wrong | Event payload, @OnSourcing, missing sourcing handler, snapshot/replay path. |
| Saga not triggered | Event type, @StatelessSaga, @OnEvent, filter condition, bus subscription, @Retry policy. |
| Projection not updated | Processor annotation, event/state-event type, repository call, retry policy. |
| Wait plan hangs | Wait command id, stage, context name, processor/function names, propagated headers. |
| Query returns wrong data | Query DSL condition, deletion guard, tenant/owner filters, projection fields, backend converter. |
| Configuration ignored | @ConfigurationProperties prefix, feature capability, conditional annotations, active profile. |
| Test fails unexpectedly | Test fixture state, owner/tenant id, fork/ref checkpoint, expected event order. |
Phase 3: Gather Evidence
Use source-first searches before edits:
rg -n "@AggregateRoot|@OnCommand|@OnSourcing|@StatelessSaga|@ProjectionProcessor" . -g "*.kt"
rg -n "CommandWait|CommandWait.chain|Command-Wait" . -g "*.kt"
rg -n "@ConfigurationProperties|ConditionalOn.*Enabled|class .*Properties" . -g "*.kt"
rg -n "AggregateSpec<|SagaSpec<|expectEventType|expectCommand|expectNoCommand" . -g "*.kt"
Find a similar working path in the same repository and list meaningful differences. Do not assume a difference is irrelevant until checked.
Phase 4: Test the Hypothesis
State one hypothesis: "stage X fails because Y." Test it with the smallest change or diagnostic. If it fails, discard the hypothesis and return to evidence gathering.
For code fixes, prefer adding or tightening:
AggregateSpec for aggregate behavior and sourcing.SagaSpec for trigger/no-command/multi-command behavior.- Unit tests for projection or configuration behavior.
- Focused integration tests only when the failure crosses infrastructure boundaries.
Red Flags
- Changing annotations without checking generated/discovered metadata.
- Fixing a projection when the event was never emitted.
- Fixing wait plan names before checking command ids.
- Adding retries before understanding the original failure.
- Updating tests to match broken state.
- Trying multiple fixes in one patch.
Completion Evidence
Finish with the exact reproducer and verification command. If the issue is not fully fixed, report the current failing stage and the remaining unknowns.
