feat: add LETTA_BACKFILL env var to disable message history backfilling (#504)

src/cli/App.tsx

@@ -6718,11 +6718,13 @@ Plan file path: ${planFilePath}`;
       });
       buffersRef.current.order.push(statusId);
       refreshDerived();
+      commitEligibleLines(buffersRef.current);
     }
   }, [
     loadingState,
     continueSession,
     messageHistory.length,
+    commitEligibleLines,
     columns,
     agentProvenance,
     agentState,
@@ -7145,6 +7147,27 @@ Plan file path: ${planFilePath}`;
                 </Box>
               )}
 
+              {/* Fallback approval UI when backfill is disabled (no liveItems) */}
+              {liveItems.length === 0 && currentApproval && (
+                <Box flexDirection="column">
+                  <InlineGenericApproval
+                    toolName={currentApproval.toolName}
+                    toolArgs={currentApproval.toolArgs}
+                    onApprove={() => handleApproveCurrent()}
+                    onApproveAlways={(scope) => handleApproveAlways(scope)}
+                    onDeny={(reason) => handleDenyCurrent(reason)}
+                    onCancel={handleCancelApprovals}
+                    isFocused={true}
+                    approveAlwaysText={
+                      currentApprovalContext?.approveAlwaysText
+                    }
+                    allowPersistence={
+                      currentApprovalContext?.allowPersistence ?? true
+                    }
+                  />
+                </Box>
+              )}
+
               {/* Subagent group display - shows running/completed subagents */}
               <SubagentGroupDisplay />
             </AnimationProvider>