System Info

N/A (I suspect the issue occurs regardless of the environment)

Information

• The official example scripts
• My own modified scripts

🐛 Describe the bug

When using pgvector with vector_io as an example, the value of results.score seems to be calculated incorrectly in the following code (https://github.com/llamastack/llama-stack/blob/main/llama_stack/providers/remote/vector_io/pgvector/pgvector.py#L136
) if dist represents a cosine distance rather than a Euclidean distance:

score = 1.0 / float(dist) if dist != 0 else float("inf")

As a result, the score can be greater than 1, which may cause thresholds to behave inaccurately.

For example, here’s a reproducer:

results = client.vector_io.query(
                vector_db_id=vector_db_id,
                query=query_text,
                params=query_params
            )
... snipped 
            for i, chunk in enumerate(results.chunks):
                score = results.scores[i]
                logging.info(f"Score: {score}")

This produces the following log:

INFO:root:Score: 1.3162429427090052

This issue may also affect other vector_io providers that use cosine distance.

Error logs

INFO:root:Score: 1.3162429427090052

Expected behavior

The score should be calculated as 1 - cosine_distance instead in case of cosine_distnace, and ranged between 0 to 1 properly if necessary with normalization.