curl --request POST \
  --url https://api.mixpeek.com/v1/retrievers/execute \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'X-Namespace: <x-namespace>' \
  --data '{
  "collection_identifiers": [
    "my_collection"
  ],
  "input_schema": {
    "query": {
      "description": "Search query",
      "required": true,
      "type": "text"
    }
  },
  "stages": [
    {
      "config": {
        "parameters": {
          "feature_uris": [
            {
              "input": {
                "text": "{{INPUT.query_text}}"
              },
              "uri": "urn:embedding:text:bge_base_en_v1_5:1"
            }
          ],
          "limit": 100
        },
        "stage_id": "feature_filter"
      },
      "description": "Feature filter stage with uppercase template namespace",
      "stage_name": "semantic_search",
      "stage_type": "filter"
    }
  ],
  "inputs": {
    "query": "machine learning"
  },
  "budget_limits": {
    "max_credits": 100,
    "max_time_ms": 60000
  }
}'

{
  "execution_id": "exec_abc123def456",
  "status": "completed",
  "documents": [
    {
      "document_id": "doc_123",
      "payload": {
        "metadata": {
          "category": "AI"
        },
        "text": "Sample content"
      },
      "score": 0.95
    },
    {
      "document_id": "doc_456",
      "payload": {
        "metadata": {
          "category": "ML"
        },
        "text": "Another document"
      },
      "score": 0.88
    }
  ],
  "pagination": {
    "has_next": true,
    "limit": 10,
    "offset": 0,
    "total": 100
  },
  "stage_statistics": {
    "stages": {},
    "total_time_ms": 0,
    "credits_used": 0
  },
  "budget": {
    "credits_remaining": 99.5,
    "credits_used": 0.5,
    "time_used_ms": 150
  },
  "error": "Retriever execution failed: Collection not found",
  "optimization_applied": true,
  "optimization_summary": {
    "optimization_time_ms": 8.2,
    "optimized_stage_count": 3,
    "original_stage_count": 5,
    "rules_applied": [
      "push_down_filters",
      "group_by_push_down"
    ],
    "stage_reduction_pct": 40
  }
}