Data And Activity
Use Data Explorer and Activity together. Data Explorer shows current read state. Activity explains how the app got there.
Data Explorer
Use Data Explorer to inspect published projection state:
- verify command results after smoke tests
- inspect list and detail projections used by custom pages
- check filters, sorting, and pagination behavior
- compare preview or test environments with production
If projection data looks wrong, inspect the event history and projection definition before changing frontend code.
Activity
Use Activity to follow runtime behavior:
- command requests
- emitted events
- policy executions
- webhook handling
- subscription delivery
- adapter calls
- runtime agent actions
- errors and retries
Activity is the first place to look when a command succeeds but downstream behavior does not happen.
Builder verification loop
After publish:
- execute one representative command
- confirm the expected event was emitted
- confirm the projection changed
- confirm policy, webhook, adapter, or subscription effects
- check errors before handing off
Agent-assisted debugging
A Design MCP agent can inspect the model and explain likely causes. A Runtime MCP agent can operate the published app. Keep those roles separate during debugging so the investigation does not accidentally mutate design state.