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Dify version

1.13.3

Cloud or Self Hosted

Cloud

Steps to reproduce

Environment

• Platform: Dify Cloud
• Retrieval mode: Hybrid search
• Embedding model: text-embedding-3-large (OpenAI)
• Rerank model: jina-reranker-v1-base-en (Jina)

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Describe the bug

When using hybrid search with a rerank model configured, setting a score threshold of 0.60 returns empty results. However, lowering the threshold to 0.45 returns chunks that display scores of 0.84 – 0.96.

If the returned chunks are displaying scores of 0.84 – 0.96, they should have easily passed a threshold of 0.60. This is contradictory and confusing behavior.

This indicates that the threshold is being applied against a different score than what is displayed in the result. The user sets a threshold expecting it to filter against the displayed score — but it does not.

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Steps to reproduce

1. Create a knowledge base with hybrid search enabled
2. Configure Jina reranker
3. Set score threshold to 0.60 on retrieval node
4. Send a query
5. Retrieval node returns empty result

6. Lower threshold to 0.45 on a second retrieval node with the same query
7. Returns 10 chunks with displayed scores of 0.84 – 0.96

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Proof

Node	Threshold	Chunks returned	Displayed score range
Node 1	0.60	0	—
Node 2	0.45	10	0.84 – 0.96

The same chunks that were blocked at threshold 0.60 display scores of 0.84 – 0.96 when retrieved at threshold 0.45. This means the threshold and the displayed score are not measuring the same thing.

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✔️ Expected Behavior

Expected behavior

The score threshold should filter against the reranked score — which is the score displayed to the user in the result.

If a chunk displays a score of 0.84, it must pass a threshold of 0.60. The threshold value and the displayed score must be consistent so that users can set a meaningful threshold based on what they see.

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❌ Actual Behavior

Actual behavior

The threshold filters against the raw hybrid score before reranking. The displayed score is the reranked score. These are two completely different scoring systems with different value distributions — but the same threshold value is silently applied to both without any indication to the user.

This means:

• A user sets threshold 0.60 expecting to filter out chunks scoring below 0.60
• But chunks scoring 0.84 – 0.96 (displayed) are blocked
• The user has no visibility into the raw hybrid score that is actually used for filtering
• The displayed score gives a false impression of what passed the threshold

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Impact

• Valid queries return empty results at reasonable threshold values
• The score threshold setting is misleading — it does not behave as the UI implies
• Users are forced to use unnecessary workarounds such as multiple retrieval nodes with different thresholds to compensate for this behavior

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Current workaround

Two retrieval nodes are required:

Node	Threshold	Purpose
Node 1	0.60	Primary retrieval
Node 2	0.45	Fallback when Node 1 returns empty
Code node	0.65	Manual filter on displayed reranked score

This workaround should not be necessary.

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Suggested fix

When a rerank model is configured, the score threshold should be applied against the reranked score — the same score that is displayed to the user. The threshold and the displayed score must always refer to the same value.

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Related issue

#3146