diff --git a/src/app/api/v1/chat/completions/route.ts b/src/app/api/v1/chat/completions/route.ts
index c264080f36..36ae77c107 100644
--- a/src/app/api/v1/chat/completions/route.ts
+++ b/src/app/api/v1/chat/completions/route.ts
@@ -84,6 +84,7 @@ export async function POST(request) {
   // OpenAI/Anthropic reject `text/plain` or missing Content-Type at the edge; matching
   // that behavior prevents a text/plain body from silently reaching provider lookup.
   const contentType = request.headers.get("content-type") ?? "";
+  const requestContentLengthHeader = request.headers.get("content-length");
   if (!contentType.toLowerCase().split(";")[0].trim().startsWith("application/json")) {
     return new Response(
       JSON.stringify({
@@ -114,8 +115,8 @@ export async function POST(request) {
     // Logs only when Content-Length is present so debug noise stays low for
     // typical chat payloads. Opt-in via OMNIROUTE_LOG_REQUEST_SHAPE=1.
     if (process.env.OMNIROUTE_LOG_REQUEST_SHAPE === "1") {
-      const ct = request.headers.get("content-type") ?? "";
-      const cl = request.headers.get("content-length");
+      const ct = contentType;
+      const cl = requestContentLengthHeader;
       if (cl && Number(cl) > 256 * 1024) {
         console.error(`[CHAT-ROUTE] large body content-type="${ct}" content-length=${cl}`);
       }
diff --git a/tests/unit/logging-opt-in-defaults.test.ts b/tests/unit/logging-opt-in-defaults.test.ts
new file mode 100644
index 0000000000..5fcd132901
--- /dev/null
+++ b/tests/unit/logging-opt-in-defaults.test.ts
@@ -0,0 +1,75 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { POST } from "../../src/app/api/v1/chat/completions/route.ts";
+import { getCallLogPipelineCaptureStreamChunks } from "../../src/lib/logEnv.ts";
+
+const originalConsoleError = console.error;
+const originalCaptureChunks = process.env.CALL_LOG_PIPELINE_CAPTURE_STREAM_CHUNKS;
+const originalRequestShape = process.env.OMNIROUTE_LOG_REQUEST_SHAPE;
+
+test.afterEach(() => {
+  console.error = originalConsoleError;
+
+  if (originalCaptureChunks === undefined) {
+    delete process.env.CALL_LOG_PIPELINE_CAPTURE_STREAM_CHUNKS;
+  } else {
+    process.env.CALL_LOG_PIPELINE_CAPTURE_STREAM_CHUNKS = originalCaptureChunks;
+  }
+
+  if (originalRequestShape === undefined) {
+    delete process.env.OMNIROUTE_LOG_REQUEST_SHAPE;
+  } else {
+    process.env.OMNIROUTE_LOG_REQUEST_SHAPE = originalRequestShape;
+  }
+});
+
+test("stream-chunk pipeline capture is disabled by default and supports explicit opt-in", () => {
+  delete process.env.CALL_LOG_PIPELINE_CAPTURE_STREAM_CHUNKS;
+  assert.equal(getCallLogPipelineCaptureStreamChunks(), false);
+
+  process.env.CALL_LOG_PIPELINE_CAPTURE_STREAM_CHUNKS = "true";
+  assert.equal(getCallLogPipelineCaptureStreamChunks(), true);
+
+  process.env.CALL_LOG_PIPELINE_CAPTURE_STREAM_CHUNKS = "false";
+  assert.equal(getCallLogPipelineCaptureStreamChunks(), false);
+});
+
+async function requestShapeMarkers(value: string | undefined): Promise<string[]> {
+  if (value === undefined) {
+    delete process.env.OMNIROUTE_LOG_REQUEST_SHAPE;
+  } else {
+    process.env.OMNIROUTE_LOG_REQUEST_SHAPE = value;
+  }
+
+  const markers: string[] = [];
+  console.error = (...args: unknown[]) => {
+    const message = args.map(String).join(" ");
+    if (message.includes("[CHAT-ROUTE] large body")) markers.push(message);
+  };
+
+  const body = JSON.stringify({
+    messages: [{ role: "user", content: "x".repeat(300 * 1024) }],
+  });
+  const response = await POST(
+    new Request("http://localhost/v1/chat/completions", {
+      method: "POST",
+      headers: {
+        "content-length": String(Buffer.byteLength(body)),
+        "content-type": "application/json",
+      },
+      body,
+    })
+  );
+  await response.text();
+  return markers;
+}
+
+test("large-request shape logging requires the exact opt-in value 1", async () => {
+  assert.deepEqual(await requestShapeMarkers(undefined), []);
+  assert.deepEqual(await requestShapeMarkers("true"), []);
+
+  const enabledMarkers = await requestShapeMarkers("1");
+  assert.equal(enabledMarkers.length, 1);
+  assert.match(enabledMarkers[0], /content-length=3072\d\d/);
+});