fix(memory): add input_type to Voyage AI embeddings for improved retrieval (#10818)

* fix(memory): add input_type to Voyage AI embeddings for improved retrieval

Voyage AI recommends passing input_type='document' when indexing and
input_type='query' when searching. This improves retrieval quality by
optimising the embedding space for each direction.

Changes:
- embedQuery now passes input_type: 'query'
- embedBatch now passes input_type: 'document'
- Batch API request_params includes input_type: 'document'
- Tests updated to verify input_type is passed correctly

* Changelog: note Voyage embeddings input_type fix (#10818) (thanks @mcinteerj)

---------

Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/memory/embeddings-voyage.test.ts

@@ -59,6 +59,7 @@ describe("voyage embedding provider", () => {
     expect(body).toEqual({
       model: "voyage-4-large",
       input: ["test query"],
+      input_type: "query",
     });
   });
 
@@ -90,6 +91,43 @@ describe("voyage embedding provider", () => {
     expect(headers["X-Custom"]).toBe("123");
   });
 
+  it("passes input_type=document for embedBatch", async () => {
+    const fetchMock = vi.fn(async () => ({
+      ok: true,
+      status: 200,
+      json: async () => ({
+        data: [{ embedding: [0.1, 0.2] }, { embedding: [0.3, 0.4] }],
+      }),
+    })) as unknown as typeof fetch;
+    vi.stubGlobal("fetch", fetchMock);
+
+    const { createVoyageEmbeddingProvider } = await import("./embeddings-voyage.js");
+    const authModule = await import("../agents/model-auth.js");
+
+    vi.mocked(authModule.resolveApiKeyForProvider).mockResolvedValue({
+      apiKey: "voyage-key-123",
+      mode: "api-key",
+      source: "test",
+    });
+
+    const result = await createVoyageEmbeddingProvider({
+      config: {} as never,
+      provider: "voyage",
+      model: "voyage-4-large",
+      fallback: "none",
+    });
+
+    await result.provider.embedBatch(["doc1", "doc2"]);
+
+    const [, init] = fetchMock.mock.calls[0] ?? [];
+    const body = JSON.parse(init?.body as string);
+    expect(body).toEqual({
+      model: "voyage-4-large",
+      input: ["doc1", "doc2"],
+      input_type: "document",
+    });
+  });
+
   it("normalizes model names", async () => {
     const { normalizeVoyageModel } = await import("./embeddings-voyage.js");
     expect(normalizeVoyageModel("voyage/voyage-large-2")).toBe("voyage-large-2");