fix(deploy): skip CDK diff for new stacks in TUI deploy

src/cli/tui/screens/deploy/useDeployFlow.ts

@@ -12,6 +12,7 @@ import {
   parsePolicyEngineOutputs,
   parsePolicyOutputs,
 } from '../../../cloudformation';
+import { checkStackStatus } from '../../../cloudformation/stack-status';
 import { DEFAULT_DEPLOY_ATTRS, computeDeployAttrs } from '../../../commands/deploy/utils.js';
 import { getErrorMessage, isChangesetInProgressError, isExpiredTokenError } from '../../../errors';
 import { ExecLogger } from '../../../logging';
@@ -612,27 +613,47 @@ export function useDeployFlow(options: DeployFlowOptions = {}): DeployFlowState
         setIsDiffLoading(true);
         setPreDeployDiffStep(prev => ({ ...prev, status: 'running' }));
         logger.startStep('Computing diff changes...');
-        switchableIoHost?.setOnRawMessage((code, _level, message, data) => {
-          logger.logDiff(code, message);
-          if (code === 'CDK_TOOLKIT_I4002') {
-            setDiffSummaries(prev => [...prev, parseStackDiff(data, message)]);
-          } else if (code === 'CDK_TOOLKIT_I4001') {
-            setNumStacksWithChanges(parseDiffResult(data).numStacksWithChanges);
-          }
-        });
-        switchableIoHost?.setVerbose(true);
+
+        // Skip diff for new stacks — there's nothing to compare against, and CDK's diff
+        // creates a temporary changeset that leaves a ghost stack which races with deploy.
+        let skipDiff = false;
         try {
-          await cdkToolkitWrapper.diff();
+          const target = context?.awsTargets[0];
+          const currentStackName = stackNames?.[0];
+          if (target && currentStackName) {
+            const status = await checkStackStatus(target.region, currentStackName);
+            skipDiff = !status.exists;
+          }
         } catch {
-          // Diff failure is non-fatal — deploy will proceed
-        } finally {
-          switchableIoHost?.setVerbose(false);
-          switchableIoHost?.setOnRawMessage(null);
-          isDiffRunningRef.current = false;
-          setIsDiffLoading(false);
-          logger.endStep('success');
-          setPreDeployDiffStep(prev => ({ ...prev, status: 'success' }));
+          // Status check failed — fall through to diff (tolerate old race)
         }
+
+        if (skipDiff) {
+          logger.log('New stack — skipping diff (nothing to compare against)');
+        } else {
+          switchableIoHost?.setOnRawMessage((code, _level, message, data) => {
+            logger.logDiff(code, message);
+            if (code === 'CDK_TOOLKIT_I4002') {
+              setDiffSummaries(prev => [...prev, parseStackDiff(data, message)]);
+            } else if (code === 'CDK_TOOLKIT_I4001') {
+              setNumStacksWithChanges(parseDiffResult(data).numStacksWithChanges);
+            }
+          });
+          switchableIoHost?.setVerbose(true);
+          try {
+            await cdkToolkitWrapper.diff();
+          } catch {
+            // Diff failure is non-fatal — deploy will proceed
+          } finally {
+            switchableIoHost?.setVerbose(false);
+            switchableIoHost?.setOnRawMessage(null);
+          }
+        }
+
+        isDiffRunningRef.current = false;
+        setIsDiffLoading(false);
+        logger.endStep('success');
+        setPreDeployDiffStep(prev => ({ ...prev, status: 'success' }));
       }
 
       setPublishAssetsStep(prev => ({ ...prev, status: 'running' }));