diff --git a/apps/web/src/lib/rewriteModelResponse.ts b/apps/web/src/lib/rewriteModelResponse.ts
index 159fe1bf75..32bfe004e0 100644
--- a/apps/web/src/lib/rewriteModelResponse.ts
+++ b/apps/web/src/lib/rewriteModelResponse.ts
@@ -11,6 +11,7 @@ import { db } from '@/lib/drizzle';
 import { KILO_ORGANIZATION_ID } from '@/lib/organizations/constants';
 import { errorExceptInTest, logExceptInTest } from '@/lib/utils.server';
 import { withRequestId } from '@/lib/ai-gateway/request-id';
+import { sanitizeJsonbValue } from '@/lib/sanitize-jsonb';
 import type { EventSourceMessage } from 'eventsource-parser';
 import { createParser } from 'eventsource-parser';
 import { after, NextResponse } from 'next/server';
@@ -109,9 +110,9 @@ async function createRequestLogCapture(
           status_code: status,
           model,
           provider,
-          request: request.body,
+          request: sanitizeJsonbValue(request.body),
           response: responseText,
-          error,
+          error: sanitizeJsonbValue(error),
         })
         .returning({ id: api_request_log.id });
       logExceptInTest(
diff --git a/apps/web/src/lib/sanitize-jsonb.test.ts b/apps/web/src/lib/sanitize-jsonb.test.ts
new file mode 100644
index 0000000000..d2a9afd305
--- /dev/null
+++ b/apps/web/src/lib/sanitize-jsonb.test.ts
@@ -0,0 +1,25 @@
+import { describe, expect, test } from '@jest/globals';
+import { sanitizeJsonbValue } from './sanitize-jsonb';
+
+describe('sanitizeJsonbValue', () => {
+  test('replaces JSONB-incompatible characters in nested values and object keys', () => {
+    const value = {
+      [`bad\ud800key`]: ['before\udc00after', { text: 'still\ud800broken' }],
+      [`nul\0key`]: 'nul\0value',
+    };
+
+    expect(sanitizeJsonbValue(value)).toEqual({
+      ['bad\ufffdkey']: ['before\ufffdafter', { text: 'still\ufffdbroken' }],
+      ['nul\ufffdkey']: 'nul\ufffdvalue',
+    });
+  });
+
+  test('preserves valid surrogate pairs and does not mutate the input', () => {
+    const value = { text: 'hello 😀' };
+
+    const sanitized = sanitizeJsonbValue(value);
+
+    expect(sanitized).toEqual(value);
+    expect(sanitized).not.toBe(value);
+  });
+});
diff --git a/apps/web/src/lib/sanitize-jsonb.ts b/apps/web/src/lib/sanitize-jsonb.ts
new file mode 100644
index 0000000000..c3afad9cbb
--- /dev/null
+++ b/apps/web/src/lib/sanitize-jsonb.ts
@@ -0,0 +1,33 @@
+/**
+ * PostgreSQL JSONB rejects escaped NUL characters and lone UTF-16 surrogates.
+ * JavaScript strings can contain both, so repair them before sending values to
+ * a JSONB column.
+ */
+function sanitizeJsonbString(value: string): string {
+  if (value.isWellFormed() && !value.includes('\0')) {
+    return value;
+  }
+
+  return value.toWellFormed().replaceAll('\0', '\ufffd');
+}
+
+export function sanitizeJsonbValue(value: unknown): unknown {
+  if (typeof value === 'string') {
+    return sanitizeJsonbString(value);
+  }
+
+  if (Array.isArray(value)) {
+    return value.map(sanitizeJsonbValue);
+  }
+
+  if (value !== null && typeof value === 'object') {
+    return Object.fromEntries(
+      Object.entries(value).map(([key, nestedValue]) => [
+        sanitizeJsonbString(key),
+        sanitizeJsonbValue(nestedValue),
+      ])
+    );
+  }
+
+  return value;
+}