fix(debug): unify LETTA_DEBUG and DEBUG gating (#1408)

Co-authored-by: Letta Code <noreply@letta.com>

src/cli/App.tsx

@@ -121,7 +121,12 @@ import {
 } from "../tools/manager";
 import type { ToolsetName, ToolsetPreference } from "../tools/toolset";
 import { formatToolsetName } from "../tools/toolset-labels";
-import { debugLog, debugLogFile, debugWarn } from "../utils/debug";
+import {
+  debugLog,
+  debugLogFile,
+  debugWarn,
+  isDebugEnabled,
+} from "../utils/debug";
 import { getVersion } from "../version";
 import {
   handleMcpAdd,
@@ -3050,7 +3055,7 @@ export default function App({
       const agentName = agentState?.name || "Unnamed Agent";
       const isResumingConversation =
         resumedExistingConversation || messageHistory.length > 0;
-      if (process.env.DEBUG) {
+      if (isDebugEnabled()) {
         console.log(
           `[DEBUG] Header: resumedExistingConversation=${resumedExistingConversation}, messageHistory.length=${messageHistory.length}`,
         );
@@ -4721,7 +4726,7 @@ export default function App({
                 })
                 .catch((err) => {
                   // Silently ignore - not critical
-                  if (process.env.DEBUG) {
+                  if (isDebugEnabled()) {
                     console.error(
                       "[DEBUG] Failed to set conversation summary:",
                       err,