diff --git a/app/api/history/route.ts b/app/api/history/route.ts
index 4174840..46ca169 100644
--- a/app/api/history/route.ts
+++ b/app/api/history/route.ts
@@ -25,6 +25,8 @@ export async function GET(req: Request) {
       user: session.user.email,
       durationMs: Date.now() - start,
       rows: rows.length,
+      topId: rows[0]?.id ?? null,
+      topUpdatedAt: rows[0]?.updated_at ?? null,
       newestAt: rows[0]?.updated_at ?? null,
       oldestAt: rows[rows.length - 1]?.updated_at ?? null,
     }, 'history.list');
diff --git a/app/page.tsx b/app/page.tsx
index 4af9797..2fa5a2e 100644
--- a/app/page.tsx
+++ b/app/page.tsx
@@ -750,15 +750,35 @@ export default function Home() {
             const title = finalMsgs.find(m => m.role === 'user')?.content.slice(0, 60) ?? 'Untitled';
             const toSave = stripMessageHtml(finalMsgs);
             const { iv, ciphertext } = await encrypt(key, { messages: toSave, model: requestModel, systemPrompt: requestSystemPrompt, title });
+            const ciphertextBytes = Math.round((ciphertext.length ?? 0) * 0.75);
+            const body = JSON.stringify({ id: chatIdRef.current, iv, ciphertext });
+            const bodyBytes = new TextEncoder().encode(body).length;
+            if (bodyBytes > LIMITS.historyBodyBytes || ciphertextBytes > LIMITS.maxCiphertextBytes) {
+              logClientEvent('history.save_too_large', 'warn', {
+                id: chatIdRef.current,
+                msgs: toSave.length,
+                bodyBytes,
+                maxBodyBytes: LIMITS.historyBodyBytes,
+                ciphertextBytes,
+                maxCiphertextBytes: LIMITS.maxCiphertextBytes,
+              });
+              return;
+            }
             const res = await fetch('/api/history', {
               method: 'POST',
               headers: { 'Content-Type': 'application/json' },
-              body: JSON.stringify({ id: chatIdRef.current, iv, ciphertext }),
+              body,
             });
             if (!res.ok) {
+              const error = (await res.text()).slice(0, LIMITS.maxClientEventValueChars);
               logClientEvent('history.save_failed', 'warn', {
                 status: res.status,
                 requestId: res.headers.get('x-request-id'),
+                id: chatIdRef.current,
+                msgs: toSave.length,
+                bodyBytes,
+                ciphertextBytes,
+                error,
               });
               return;
             }
@@ -767,8 +787,8 @@ export default function Home() {
             rememberActiveHistoryChat(id);
             setSavedFlash(true);
             setTimeout(() => setSavedFlash(false), 2000);
-          } catch {
-            logClientEvent('history.save_failed', 'error');
+          } catch (error) {
+            logClientEvent('history.save_failed', 'error', getClientErrorDetails(error));
           }
         })();
       }
diff --git a/tests/unit.test.ts b/tests/unit.test.ts
index c349509..450b639 100644
--- a/tests/unit.test.ts
+++ b/tests/unit.test.ts
@@ -417,6 +417,59 @@ test('history-loaded chats persist across refreshes and clear correctly', () =>
   );
 });
 
+test('history drawer still loads the latest 50 saved chats', () => {
+  const pageSource = readFileSync(join(import.meta.dirname, '../app/page.tsx'), 'utf8');
+  const historyRouteSource = readFileSync(join(import.meta.dirname, '../app/api/history/route.ts'), 'utf8');
+  assert.ok(
+    pageSource.includes("const res = await fetch('/api/history');"),
+    'history drawer should load saved chats from the history list endpoint',
+  );
+  assert.ok(
+    pageSource.includes('await loadHistory();'),
+    'opening the history drawer should refresh the saved chat list',
+  );
+  assert.ok(
+    historyRouteSource.includes('ORDER BY updated_at DESC LIMIT 50'),
+    'history list endpoint should return the latest 50 saved chats first',
+  );
+  assert.ok(
+    historyRouteSource.includes('topUpdatedAt: rows[0]?.updated_at ?? null'),
+    'history list logs should include the updated_at timestamp of the top visible row',
+  );
+  assert.ok(
+    historyRouteSource.includes("}, 'history.list');"),
+    'history list endpoint should continue logging the visible latest-history window',
+  );
+});
+
+test('history save logs meaningful failure details before and after the network request', () => {
+  const pageSource = readFileSync(join(import.meta.dirname, '../app/page.tsx'), 'utf8');
+  assert.ok(
+    pageSource.includes('const bodyBytes = new TextEncoder().encode(body).length;'),
+    'history saves should measure request size before posting so oversized chats are diagnosable',
+  );
+  assert.ok(
+    pageSource.includes('bodyBytes > LIMITS.historyBodyBytes || ciphertextBytes > LIMITS.maxCiphertextBytes'),
+    'history saves should log when the encrypted payload is too large to persist',
+  );
+  assert.ok(
+    pageSource.includes("logClientEvent('history.save_too_large', 'warn', {"),
+    'history saves should emit a dedicated too-large log event with size details',
+  );
+  assert.ok(
+    pageSource.includes("const error = (await res.text()).slice(0, LIMITS.maxClientEventValueChars);"),
+    'history save failures should capture the server error text for debugging',
+  );
+  assert.ok(
+    pageSource.includes('bodyBytes,'),
+    'history save failure logs should include the request body size',
+  );
+  assert.ok(
+    pageSource.includes('ciphertextBytes,'),
+    'history save failure logs should include the ciphertext size',
+  );
+});
+
 // ── settings validation ────────────────────────────────────────────────────────
 
 test('validateSettingsRequest: validates and defaults girlMode', () => {