diff --git a/open-sse/handlers/chatCore/attemptLogging.ts b/open-sse/handlers/chatCore/attemptLogging.ts
index c8ac0303c8a..5ce51206b06 100644
--- a/open-sse/handlers/chatCore/attemptLogging.ts
+++ b/open-sse/handlers/chatCore/attemptLogging.ts
@@ -25,6 +25,7 @@ import { emit } from "@/lib/events/eventBus";
 import { maybeLogToolCallSpecViolation } from "./toolCallSpecViolationAudit.ts";
 import type { RequestCompletedPayload, RequestFailedPayload } from "@/lib/events/types";
 import { saveCallLog, saveUpstreamHttpAttempt } from "@/lib/usageDb";
+import { captureReasoningSnapshotMeta } from "@/lib/usage/callLogs";
 import type { VideoBridgeLogRedactionEntry } from "@/lib/guardrails/videoBridge";
 import { redactVideoTranscriptFieldsForLog } from "@/lib/guardrails/videoBridgeSnapshotRedaction";
 import { FORMATS } from "../../translator/formats.ts";
@@ -549,6 +550,9 @@ export function persistAttemptLogs(args: PersistAttemptLogsArgs, ctx: PersistAtt
     ? { _omniroute_omitted: "video-transcript" }
     : (responseBody ?? (status >= 400 ? providerResponse : undefined));
   const retainedError = videoContentRemoved && error ? "[omitted: video transcript]" : error;
+  // Keep reasoning observability even though no-log policy discards all
+  // request/response payloads. Only source and character-count scalars survive.
+  const noLogReasoningSnapshot = noLogEnabled ? captureReasoningSnapshotMeta(retainedResponse) : null;
 
   const providerWarnings = extractProviderWarnings(providerResponse, clientResponse, responseBody);
   if (providerWarnings.length > 0) {
@@ -672,17 +676,19 @@ export function persistAttemptLogs(args: PersistAttemptLogsArgs, ctx: PersistAtt
     // Encrypted-reasoning observation: stream-side flag plus duration, and
     // the two request bodies so the sink can read effort values
     // (requested from the client body, upstream from the post-strip body).
-    reasoningMeta: args.reasoningMeta ?? null,
+    reasoningMeta: noLogReasoningSnapshot
+      ? { ...(args.reasoningMeta ?? {}), ...noLogReasoningSnapshot }
+      : (args.reasoningMeta ?? null),
     clientRequestBody: body ?? null,
     upstreamRequestBody: providerRequest ?? null,
-    requestBody: cloneBoundedChatLogPayload(
+    requestBody: noLogEnabled ? null : cloneBoundedChatLogPayload(
       attachLogMeta(truncateForLog(retainedRequest as Record<string, unknown>), {
         ...accountRotationMeta,
         claudePromptCache: claudeCacheMeta,
         geminiPromptCache,
       })
     ),
-    responseBody: cloneBoundedChatLogPayload(
+    responseBody: noLogEnabled ? null : cloneBoundedChatLogPayload(
       attachLogMeta(truncateForLog(retainedResponse as Record<string, unknown>), {
         ...accountRotationMeta,
         claudePromptCache: claudeCacheMeta
diff --git a/src/lib/usage/callLogs.ts b/src/lib/usage/callLogs.ts
index ceb8bc2aee6..51fd6bf4ec2 100644
--- a/src/lib/usage/callLogs.ts
+++ b/src/lib/usage/callLogs.ts
@@ -341,14 +341,30 @@ function snapshotHasOpaqueReasoningItem(body: unknown): boolean {
 function resolveReasoningObservation(
   usageReasoning: number | null,
   responseBody: unknown,
-  streamMeta?: { encryptedSeen?: boolean } | null
+  streamMeta?: {
+    encryptedSeen?: boolean;
+    snapshotSource?: string | null;
+    snapshotChars?: number | null;
+  } | null
 ): { source: string | null; chars: number | null } {
-  if (streamMeta?.encryptedSeen === true || snapshotHasOpaqueReasoningItem(responseBody)) {
+  if (
+    streamMeta?.encryptedSeen === true ||
+    streamMeta?.snapshotSource === "encrypted" ||
+    snapshotHasOpaqueReasoningItem(responseBody)
+  ) {
     return { source: "encrypted", chars: null };
   }
   if (usageReasoning != null && usageReasoning > 0) {
     return { source: "usage", chars: null };
   }
+  // A no-log request keeps only scalars from its live response, not a cloned body.
+  if (
+    (streamMeta?.snapshotSource === "content" || streamMeta?.snapshotSource === "think") &&
+    typeof streamMeta.snapshotChars === "number" &&
+    streamMeta.snapshotChars > 0
+  ) {
+    return { source: streamMeta.snapshotSource, chars: streamMeta.snapshotChars };
+  }
   const observed = getObservedReasoning(extractAssistantMessage(responseBody));
   if (observed.chars > 0) {
     return { source: observed.source, chars: observed.chars };
@@ -356,6 +372,18 @@ function resolveReasoningObservation(
   return { source: null, chars: null };
 }
 
+/**
+ * Read numerical reasoning observations from the live response before a no-log
+ * attempt drops its payload. Never retain content or encrypted reasoning blobs.
+ */
+export function captureReasoningSnapshotMeta(responseBody: unknown): {
+  snapshotSource: string | null;
+  snapshotChars: number | null;
+} {
+  const { source, chars } = resolveReasoningObservation(null, responseBody);
+  return { snapshotSource: source, snapshotChars: chars };
+}
+
 function hasCallLogsColumn(columnName: string): boolean {
   // One PRAGMA per INSERT is wasteful; the cached answer is invalidated only
   // when a write fails with "no such column" (concurrent migration race).
diff --git a/tests/unit/chatcore-attempt-logging.test.ts b/tests/unit/chatcore-attempt-logging.test.ts
index 6cecbcc9ff9..9ba8755676d 100644
--- a/tests/unit/chatcore-attempt-logging.test.ts
+++ b/tests/unit/chatcore-attempt-logging.test.ts
@@ -15,7 +15,7 @@ const testDataDir = fs.mkdtempSync(path.join(os.tmpdir(), "omni-attempt-logging-
 process.env.DATA_DIR = testDataDir;
 
 const coreDb = await import("../../src/lib/db/core.ts");
-const { getCallLogById, getCallLogs } = await import("../../src/lib/usage/callLogs.ts");
+const { getCallLogById, getCallLogs, waitForCallLogSaves } = await import("../../src/lib/usage/callLogs.ts");
 const { persistAttemptLogs } = await import("../../open-sse/handlers/chatCore/attemptLogging.ts");
 const { getAuditLog } = await import("../../src/lib/compliance/index.ts");
 
@@ -315,3 +315,44 @@ test("combo attempts that share pendingRequestId both land, keyed independently
   assert.equal(row2.correlationId, traceId2);
   assert.equal(row2.comboStepId, "my-combo-model-3");
 });
+
+test("no-log attempt skips traversing request and response bodies while retaining usage counters", async () => {
+  const traceId = "no-log-heap-protection";
+  const body: Record<string, unknown> = {};
+  Object.defineProperty(body, "expensive", {
+    enumerable: true,
+    get() {
+      throw new Error("no-log body must not be cloned");
+    },
+  });
+  persistAttemptLogs(
+    { status: 200, tokens: { input: 125_000, output: 2 }, responseBody: { choices: [] } },
+    baseCtx({ pendingRequestId: traceId, body, noLogEnabled: true })
+  );
+  assert.equal(await waitForCallLogSaves(CALL_LOG_SETTLE_TIMEOUT_MS), true);
+  const rows = await getCallLogs({ correlationId: traceId, limit: 5 });
+  assert.equal(rows.length, 1);
+  assert.equal(rows[0]?.status, 200);
+  assert.equal(rows[0]?.detailState, "none");
+  assert.equal(rows[0]?.tokens.in, 125_000);
+});
+
+test("no-log responses preserve scalar reasoning observations without storing response bodies", async () => {
+  for (const [suffix, responseBody, expectedSource, expectedChars] of [
+    ["content", { choices: [{ message: { reasoning_content: "private thoughts" } }] }, "content", 16],
+    ["encrypted", { output: [{ type: "reasoning", encrypted_content: "private opaque blob" }] }, "encrypted", null],
+  ] as const) {
+    const id = `no-log-reasoning-${suffix}`;
+    persistAttemptLogs(
+      { status: 200, tokens: { input: 4, output: 2 }, responseBody },
+      baseCtx({ pendingRequestId: id, noLogEnabled: true })
+    );
+    assert.equal(await waitForCallLogSaves(CALL_LOG_SETTLE_TIMEOUT_MS), true);
+    const rows = await getCallLogs({ correlationId: id, limit: 5 });
+    assert.equal(rows.length, 1);
+    assert.equal(rows[0]?.detailState, "none");
+    assert.equal(rows[0]?.hasResponseBody, false);
+    assert.equal(rows[0]?.reasoningSource, expectedSource);
+    assert.equal(rows[0]?.reasoningChars, expectedChars);
+  }
+});