An embedding model's query_prefix, put before questions and never before documents

Qwen3-Embedding and models like it are trained with an instruction on the
query side only. The prefix goes before the question a knowledge-base
search embeds, at answer time and in the admin API's search; documents
reach /v1/embeddings from llmgw-kb as they are.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/admin-api.openapi.json

@@ -8710,6 +8710,10 @@
             "$ref": "#/components/schemas/catalog.Capabilities",
             "description": "Capabilities is what this model can do beyond plain completion."
           },
+          "query_prefix": {
+            "type": "string",
+            "description": "QueryPrefix is put before a question an embedding model embeds for a knowledge-base search; documents are embedded without it. Models trained with an instruction on the query side want it, Qwen3-Embedding \"Instruct: Given a web search query, retrieve relevant passages that answer the query\\nQuery: \" for one."
+          },
           "role": {
             "type": "string",
             "description": "Role \"guard\" is a model that judges the gateway's traffic for the guardrails rather than serving clients: hidden from /v1/models and the chat page, refused to any key that names it, critical by default, and always running. Guard says how its answers are read."