Add integration test runs a real rerank #2600

Current behavior

• In tests, the reranker points at the real dev endpoint ([test-reranking-providers-config.yaml#L15](

  data-api/src/main/resources/test-reranking-providers-config.yaml

  Line 15 in 02d0423

  url: https://us-west-2.api-dev.ai.datastax.com/nvidia/v1/ranking

  ), loaded in [DseTestResource.java#L131](

  data-api/src/test/java/io/stargate/sgv2/jsonapi/testresource/DseTestResource.java

  Line 131 in 02d0423

  propsBuilder.put("RERANKING_CONFIG_RESOURCE", "test-reranking-providers-config.yaml");

  )). CI can't call that endpoint.
• So no existing test ever completes a rerank:
  • every findAndRerank IT only checks errors ([FindAndRerankCollectionIntegrationTest.java](https://github.com/stargate/data-api/blob/02d0423347cb2c382c9b7535903a54d2c5e143f6/src/test/java/io/stargate/sgv2/jsonapi/api/v1/FindAndRerankCollectionIntegrationTest.java));
  • the MCP IT avoids the reranker on purpose. It uses a rerankOn field that doesn't exist, so all documents are dropped before reranking ([CollectionCommandToolsMcpIntegrationTest.java#L193-L212](

    data-api/src/test/java/io/stargate/sgv2/jsonapi/api/v1/mcp/CollectionCommandToolsMcpIntegrationTest.java

    Lines 193 to 212 in 02d0423

    	void testFindAndRerankToolCall() {
    	callToolAndAssert(
    	CommandName.Names.FIND_AND_RERANK,
    	Map.of(
    	"keyspace",
    	keyspaceName,
    	"collection",
    	collectionName,
    	"sort",
    	Map.of("$hybrid", Map.of("$vector", List.of(0.25, 0.25, 0.25, 0.25, 0.25))),
    	"options",
    	Map.of("rerankQuery", "I like cheese", "rerankOn", "content")),
    	assertDataOnly(
    	data -> {
    	// Use an inexistent field "content" in rerankOn, so it will not do the actual rerank
    	// operation(cannot call reranker) and return an empty result
    	JsonArray docs = data.getJsonArray("documents");
    	assertNotNull(docs);
    	assertEquals(0, docs.size());
    	}));

    )).
• DataApiResponseValidator.wasSuccessful() doesn't support findAndRerank yet ([DataApiResponseValidator.java#L74-L76](

  data-api/src/test/java/io/stargate/sgv2/jsonapi/api/v1/util/DataApiResponseValidator.java

  Lines 74 to 76 in 02d0423

  	default ->
  	throw new IllegalArgumentException(
  	"DataApiResponseValidator: Unexpected command name: " + commandName);

  )).

Why fix it

• We can't test the core of the feature: result order, how many candidates each leg reads, and the default rerank query and passage.

Implementation and acceptance criteria

Add a separate successful-reranking test PR before the two #2599 implementation PRs. Use class-scoped, dynamic-port WireMock URLs with the production Nvidia HTTP client. Scores must depend on passage content rather than concurrent batch arrival, and provider responses must include rankings[].logit.

Exercise existing $hybrid requests and the local embedding test provider. Cover default and explicit queries/passages, final ordering, projection, result limits, optional scores, hybrid deduplication, batching, and zero provider calls when no usable candidates remain. Extend DataApiResponseValidator.wasSuccessful() and replace the MCP missing-field workaround with successful reranking of existing documents.

Seed 60 unique passages, assert every passage reaches the HTTP reranker exactly once, and give a candidate beyond position 50 the highest score. Add database-free HTTP client coverage for serialization, headers, batch indices, response decoding, and usage. Packaged integration tests run in the existing DSE/HCD CI matrix, with lexical cases gated to HCD.

Public single-leg request syntax is outside this PR.

Draft PRs

PR #2605 adds the successful HTTP/MCP coverage. It is the first draft in the stack followed by #2606 and #2607.