Interactive debugging in dagster assets                              2026-04-06
-------------------------------------------------------------------------------

The dagster built in pdb functionality is limited:
 - no autocomplete (using TAB)
 - no browsing of past commands (arrow keys)

To improve experience:

 1. Replace pdb with the drop in replacement of pdb++
    https://github.com/pdbpp/pdbpp
 2. Use a custom helper function to set a breakpoint:
    https://bardos.dev/gists/2026-04-06_debug_tty_dagster.py
 3. With the custom debug function, it is now also possible to
    set the breakpoint in a nested function, without passing
    the context (AssetExecutionContext) downstream to this
    particular function I want to debug.

When custom debugger is needed, inside the dagster asset:

  from dagster_module.debug_tty_dagster import set_trace
  ...
  set_trace()

Then start materialization with:

  $ dagster asset materialize \
      -f dagster_module/definitions.py \
      --select src/my_asset