[Bug]: DRIFT `drift_k_followups` Configuration Parameter Not Fully Utilized

[arvin8]

Do you need to file an issue?

• I have searched the existing issues and this bug is not already filed.
• My model is hosted on OpenAI or Azure. If not, please look at the "model providers" issue and don't file a new one here.
• I believe this is a legitimate bug, not just a question. If this is a question, please use the Discussions area.

Describe the bug

The drift_k_followups configuration parameter is documented but doesn't actually control how many follow-up queries are generated. The default prompt template has a hardcoded "Generate at least five good follow-up queries" instruction, so changing the config from 5 to 10, 15, or 20 has no effect.

Steps to reproduce

1. Configure DRIFT search in settings.yaml:

drift_search:
  drift_k_followups: 15  # Set to anything > 5
  n_depth: 2
  primer_folds: 3

2. Run a DRIFT query
3. Check the logs/output for generated follow-ups

Expected Behavior

Expected Behavior:

Setting drift_k_followups: 15 should generate 15 follow-up queries per iteration.

Actual Behavior:

Only 5 follow-up queries are generated, regardless of the config value.

GraphRAG Config Used

# Paste your config here

Logs and screenshots

No response

Additional Information

Root Cause:

Looking at the source code:

• graphrag/query/drift/search.py (line 240) correctly limits selection: actions = actions[:self.context_builder.config.drift_k_followups]
• But the default prompt template contains: "Generate at least five good follow-up queries" (hardcoded)

So the code is ready to accept 15 queries, but the prompt only generates 5.

Impact:

• Users expect documented config parameters to work
• Changing the config has no visible effect, which is confusing
• Limits DRIFT's exploration depth for users who need it
• All other DRIFT parameters (n_depth, primer_folds, local_search_max_data_tokens) work correctly - only this one doesn't

Workaround:

Yes, I can create a custom prompt template with the desired number and set drift_search.prompt: "custom_prompt.txt" in config.

However: A documented configuration parameter should work out-of-the-box without requiring custom prompt templates. This creates unnecessary friction and makes the config parameter misleading.

Suggested Fix:

Parameterize the prompt template to use the config value:

Generate at least {drift_k_followups} good follow-up queries.

This would maintain backward compatibility (default could stay 5) while making the parameter functional.

Environment:

• GraphRAG: latest (pip install)
• Python: 3.12
• OS: macOS

Documentation Reference:

https://microsoft.github.io/graphrag/config/yaml/ states:

drift_k_followups: int - The number of top global results to retrieve

Thanks for the great project! This is just a config consistency issue that affects user experience.