diff --git a/apps/web/src/lib/code-reviews/db/code-reviews.test.ts b/apps/web/src/lib/code-reviews/db/code-reviews.test.ts
index 22f2a944b9..cbc920a827 100644
--- a/apps/web/src/lib/code-reviews/db/code-reviews.test.ts
+++ b/apps/web/src/lib/code-reviews/db/code-reviews.test.ts
@@ -36,6 +36,8 @@ import {
   findPreviousCompletedReview,
   updateCodeReviewStatus,
   resetCodeReviewForRetry,
+  failReservedQueuedReview,
+  updatePreviousReviewSummary,
 } from './code-reviews';
 
 const REPO = `test-org/session-continuation-${Date.now()}`;
@@ -1970,6 +1972,49 @@ describe('resetCodeReviewForRetry', () => {
     });
     expect(stored?.status).toBe('pending');
   });
+
+  it('persists sanitized previous summaries while preserving null and valid markdown', async () => {
+    const reviewId = await insertReview('pending');
+
+    await updatePreviousReviewSummary(reviewId, {
+      body: '## Summary\nactual\0NUL, literal \\u0000, and 😀',
+      headSha: 'previous-head-sha',
+    });
+
+    const stored = await db.query.cloud_agent_code_reviews.findFirst({
+      where: eq(cloud_agent_code_reviews.id, reviewId),
+    });
+    expect(stored?.previous_summary_body).toBe(
+      '## Summary\nactual\ufffdNUL, literal \\u0000, and 😀'
+    );
+    expect(stored?.previous_summary_head_sha).toBe('previous-head-sha');
+
+    await updatePreviousReviewSummary(reviewId, { body: null, headSha: null });
+
+    const cleared = await db.query.cloud_agent_code_reviews.findFirst({
+      where: eq(cloud_agent_code_reviews.id, reviewId),
+    });
+    expect(cleared?.previous_summary_body).toBeNull();
+    expect(cleared?.previous_summary_head_sha).toBeNull();
+  });
+
+  it('marks a reserved review failed when its dispatch error contains a NUL character', async () => {
+    const reservationId = crypto.randomUUID();
+    const reviewId = await insertReview('queued', {
+      dispatch_reservation_id: reservationId,
+    });
+
+    await expect(
+      failReservedQueuedReview(reviewId, reservationId, 'Dispatch failed: actual\0NUL')
+    ).resolves.toBe(true);
+
+    const stored = await db.query.cloud_agent_code_reviews.findFirst({
+      where: eq(cloud_agent_code_reviews.id, reviewId),
+    });
+    expect(stored?.status).toBe('failed');
+    expect(stored?.dispatch_reservation_id).toBeNull();
+    expect(stored?.error_message).toBe('Dispatch failed: actual\ufffdNUL');
+  });
 });
 
 describe('listCodeReviews narrows the list DTO', () => {
diff --git a/apps/web/src/lib/code-reviews/db/code-reviews.ts b/apps/web/src/lib/code-reviews/db/code-reviews.ts
index 00435b7e2b..5af78dcb42 100644
--- a/apps/web/src/lib/code-reviews/db/code-reviews.ts
+++ b/apps/web/src/lib/code-reviews/db/code-reviews.ts
@@ -32,6 +32,7 @@ import {
 } from 'drizzle-orm';
 import { captureException } from '@sentry/nextjs';
 import { logExceptInTest } from '@/lib/utils.server';
+import { sanitizePostgresString } from '@/lib/sanitize-jsonb';
 import { CreateReviewParamsSchema } from '../core';
 import { assertCouncilCreationAllowed } from '../core/council-entitlement';
 import { codeReviewLedgerIntent, settleCodeReviewLedgerRow } from '../code-review-ledger';
@@ -1213,7 +1214,7 @@ export async function failReservedQueuedReview(
   try {
     const updateData: Partial<typeof cloud_agent_code_reviews.$inferInsert> = {
       status: 'failed',
-      error_message: errorMessage,
+      error_message: sanitizePostgresString(errorMessage),
       dispatch_reservation_id: null,
       completed_at: new Date().toISOString(),
       updated_at: new Date().toISOString(),
@@ -1363,7 +1364,7 @@ export async function updatePreviousReviewSummary(
     await db
       .update(cloud_agent_code_reviews)
       .set({
-        previous_summary_body: summary.body,
+        previous_summary_body: summary.body === null ? null : sanitizePostgresString(summary.body),
         previous_summary_head_sha: summary.headSha,
         updated_at: new Date().toISOString(),
       })
diff --git a/apps/web/src/lib/sanitize-jsonb.test.ts b/apps/web/src/lib/sanitize-jsonb.test.ts
index d2a9afd305..6ee80a303a 100644
--- a/apps/web/src/lib/sanitize-jsonb.test.ts
+++ b/apps/web/src/lib/sanitize-jsonb.test.ts
@@ -1,5 +1,12 @@
 import { describe, expect, test } from '@jest/globals';
-import { sanitizeJsonbValue } from './sanitize-jsonb';
+import { sanitizeJsonbValue, sanitizePostgresString } from './sanitize-jsonb';
+
+describe('sanitizePostgresString', () => {
+  test('replaces NUL characters and lone surrogates without changing valid text', () => {
+    expect(sanitizePostgresString('before\0after\ud800')).toBe('before\ufffdafter\ufffd');
+    expect(sanitizePostgresString('`\\u0000` 😀')).toBe('`\\u0000` 😀');
+  });
+});
 
 describe('sanitizeJsonbValue', () => {
   test('replaces JSONB-incompatible characters in nested values and object keys', () => {
diff --git a/apps/web/src/lib/sanitize-jsonb.ts b/apps/web/src/lib/sanitize-jsonb.ts
index c3afad9cbb..dd614430a3 100644
--- a/apps/web/src/lib/sanitize-jsonb.ts
+++ b/apps/web/src/lib/sanitize-jsonb.ts
@@ -1,9 +1,9 @@
 /**
- * PostgreSQL JSONB rejects escaped NUL characters and lone UTF-16 surrogates.
+ * PostgreSQL text rejects NUL characters; JSONB also rejects lone UTF-16 surrogates.
  * JavaScript strings can contain both, so repair them before sending values to
- * a JSONB column.
+ * a PostgreSQL column.
  */
-function sanitizeJsonbString(value: string): string {
+export function sanitizePostgresString(value: string): string {
   if (value.isWellFormed() && !value.includes('\0')) {
     return value;
   }
@@ -13,7 +13,7 @@ function sanitizeJsonbString(value: string): string {
 
 export function sanitizeJsonbValue(value: unknown): unknown {
   if (typeof value === 'string') {
-    return sanitizeJsonbString(value);
+    return sanitizePostgresString(value);
   }
 
   if (Array.isArray(value)) {
@@ -23,7 +23,7 @@ export function sanitizeJsonbValue(value: unknown): unknown {
   if (value !== null && typeof value === 'object') {
     return Object.fromEntries(
       Object.entries(value).map(([key, nestedValue]) => [
-        sanitizeJsonbString(key),
+        sanitizePostgresString(key),
         sanitizeJsonbValue(nestedValue),
       ])
     );