diff --git a/src/agents/gigachat-stream.tool-calls.test.ts b/src/agents/gigachat-stream.tool-calls.test.ts
index e282d4995e8..873cc02e4e7 100644
--- a/src/agents/gigachat-stream.tool-calls.test.ts
+++ b/src/agents/gigachat-stream.tool-calls.test.ts
@@ -34,6 +34,7 @@ describe("createGigachatStreamFn tool calling", () => {
   beforeEach(() => {
     vi.clearAllMocks();
     clientConfigs.length = 0;
+    vi.unstubAllEnvs();
   });
 
   it("round-trips sanitized tool names for streamed function calls", async () => {
@@ -177,6 +178,75 @@ describe("createGigachatStreamFn tool calling", () => {
     expect(event.content).toEqual([{ type: "text", text: "final tail" }]);
   });
 
+  it("prefers the resolved GigaChat baseUrl over the env override", async () => {
+    vi.stubEnv("GIGACHAT_BASE_URL", "https://env-host.example/api/v1");
+    request.mockResolvedValueOnce({
+      status: 200,
+      data: createSseStream(['data: {"choices":[{"delta":{"content":"done"}}]}', "data: [DONE]"]),
+    });
+
+    const streamFn = createGigachatStreamFn({
+      baseUrl: "https://resolved-host.example/api/v1",
+      authMode: "oauth",
+    });
+
+    const stream = await streamFn(
+      { api: "gigachat", provider: "gigachat", id: "GigaChat-2-Max" } as never,
+      { messages: [], tools: [] } as never,
+      { apiKey: "token" } as never,
+    );
+
+    const event = await stream.result();
+
+    expect(event.content).toEqual([{ type: "text", text: "done" }]);
+    expect(clientConfigs).toHaveLength(1);
+    expect(clientConfigs[0]?.baseUrl).toBe("https://resolved-host.example/api/v1");
+  });
+
+  it("forwards resolved model headers and caller headers on the custom transport", async () => {
+    request.mockResolvedValueOnce({
+      status: 200,
+      data: createSseStream(['data: {"choices":[{"delta":{"content":"done"}}]}', "data: [DONE]"]),
+    });
+
+    const streamFn = createGigachatStreamFn({
+      baseUrl: "https://gigachat.devices.sberbank.ru/api/v1",
+      authMode: "oauth",
+    });
+
+    const stream = await streamFn(
+      {
+        api: "gigachat",
+        provider: "gigachat",
+        id: "GigaChat-2-Max",
+        headers: {
+          "X-Model-Header": "model-value",
+        },
+      } as never,
+      { messages: [], tools: [] } as never,
+      {
+        apiKey: "token",
+        headers: {
+          "X-Caller-Header": "caller-value",
+        },
+      } as never,
+    );
+
+    const event = await stream.result();
+
+    expect(event.content).toEqual([{ type: "text", text: "done" }]);
+    expect(request).toHaveBeenCalledWith(
+      expect.objectContaining({
+        headers: expect.objectContaining({
+          Authorization: "Bearer test-token",
+          Accept: "text/event-stream",
+          "X-Model-Header": "model-value",
+          "X-Caller-Header": "caller-value",
+        }),
+      }),
+    );
+  });
+
   it("sanitizes historical assistant/tool result names in the outbound request", async () => {
     request.mockResolvedValueOnce({
       status: 200,
diff --git a/src/agents/gigachat-stream.ts b/src/agents/gigachat-stream.ts
index 504fe61a0a0..6714c599a7d 100644
--- a/src/agents/gigachat-stream.ts
+++ b/src/agents/gigachat-stream.ts
@@ -43,6 +43,15 @@ function stripLeakedFunctionCallPrelude(text: string): string {
   return text.replace(/^\s*assistant\s+function\s+call(?:\s*([A-Za-z0-9_.:/-]+))?\s*\{\s*/i, "");
 }
 
+function resolveGigachatModelHeaders(model: {
+  headers?: unknown;
+}): Record<string, string> | undefined {
+  if (!model.headers || typeof model.headers !== "object" || Array.isArray(model.headers)) {
+    return undefined;
+  }
+  return model.headers as Record<string, string>;
+}
+
 // ── Function name sanitization ──────────────────────────────────────────────
 // GigaChat requires function names to be alphanumeric + underscore only.
 
@@ -434,9 +443,10 @@ async function withRetry<T>(
 // ── Stream function ─────────────────────────────────────────────────────────
 
 export function createGigachatStreamFn(opts: GigachatStreamOptions): StreamFn {
+  const configuredBaseUrl = opts.baseUrl.trim();
   const envBaseUrl = process.env.GIGACHAT_BASE_URL?.trim();
   const effectiveBaseUrl =
-    envBaseUrl || opts.baseUrl || "https://gigachat.devices.sberbank.ru/api/v1";
+    configuredBaseUrl || envBaseUrl || "https://gigachat.devices.sberbank.ru/api/v1";
 
   const envVerifySsl = process.env.GIGACHAT_VERIFY_SSL_CERTS?.trim().toLowerCase();
   const insecureTls = opts.insecureTls ?? (envVerifySsl === "false" || envVerifySsl === "0");
@@ -650,17 +660,21 @@ export function createGigachatStreamFn(opts: GigachatStreamOptions): StreamFn {
         const requestId = randomUUID();
         log.debug(`GigaChat request ${requestId}: starting`);
 
+        const headers: Record<string, string> = {
+          ...resolveGigachatModelHeaders(model),
+          ...options?.headers,
+          Authorization: `Bearer ${accessToken}`,
+          Accept: "text/event-stream",
+          "Cache-Control": "no-store",
+          "X-Request-ID": requestId,
+        };
+
         const response = await axiosClient.request({
           method: "POST",
           url: "/chat/completions",
           data: { ...chatRequest, stream: true },
           responseType: "stream",
-          headers: {
-            Authorization: `Bearer ${accessToken}`,
-            Accept: "text/event-stream",
-            "Cache-Control": "no-store",
-            "X-Request-ID": requestId,
-          },
+          headers,
           signal: options?.signal,
         });