fix(import): detect already-imported resources early and improve CFN error messages

Check deployed-state.json before making any config changes to catch
resources already imported in the current project. Also detect the
"already exists in stack" CFN error and provide a friendlier message
explaining the resource must be removed from the other stack first.

Author: jesseturner21

src/cli/commands/import/__tests__/import-runtime-handler.test.ts

@@ -21,6 +21,7 @@ const mockCopyAgentSource = vi.fn();
 const mockToStackName = vi.fn();
 
 const mockParseAndValidateArn = vi.fn();
+const mockFindResourceInDeployedState = vi.fn();
 
 vi.mock('../import-utils', () => ({
   resolveProjectContext: (...args: unknown[]) => mockResolveProjectContext(...args),
@@ -29,6 +30,7 @@ vi.mock('../import-utils', () => ({
   copyAgentSource: (...args: unknown[]) => mockCopyAgentSource(...args),
   toStackName: (...args: unknown[]) => mockToStackName(...args),
   parseAndValidateArn: (...args: unknown[]) => mockParseAndValidateArn(...args),
+  findResourceInDeployedState: (...args: unknown[]) => mockFindResourceInDeployedState(...args),
 }));
 
 const mockGetAgentRuntimeDetail = vi.fn();
@@ -128,6 +130,8 @@ function setupDefaultMocks() {
     resourceId: 'rt-123',
   });
 
+  mockFindResourceInDeployedState.mockResolvedValue(undefined);
+
   mockConfigIO.readProjectSpec.mockResolvedValue({ ...defaultProjectSpec, runtimes: [] });
 }
 

src/cli/commands/import/import-memory.ts

@@ -6,6 +6,7 @@ import { silentIoHost } from '../../cdk/toolkit-lib';
 import { ExecLogger } from '../../logging';
 import { bootstrapEnvironment, buildCdkProject, checkBootstrapNeeded, synthesizeCdk } from '../../operations/deploy';
 import {
+  findResourceInDeployedState,
   parseAndValidateArn,
   resolveImportTarget,
   resolveProjectContext,
@@ -158,6 +159,20 @@ export async function handleImportMemory(options: ImportResourceOptions): Promis
         logPath: logger.getRelativeLogPath(),
       };
     }
+    const targetName = target.name ?? 'default';
+    const existingResource = await findResourceInDeployedState(ctx.configIO, targetName, 'memory', memoryId);
+    if (existingResource) {
+      const error = `Memory "${memoryId}" is already imported in this project as "${existingResource}". Remove it first before re-importing.`;
+      logger.endStep('error', error);
+      logger.finalize(false);
+      return {
+        success: false,
+        error,
+        resourceType: 'memory',
+        resourceName: localName,
+        logPath: logger.getRelativeLogPath(),
+      };
+    }
     logger.endStep('success');
 
     // 5. Add to project config
@@ -180,7 +195,6 @@ export async function handleImportMemory(options: ImportResourceOptions): Promis
 
     const synthInfo = await toolkitWrapper.synth();
     const assemblyDirectory = synthInfo.assemblyDirectory;
-    const targetName = target.name ?? 'default';
     const stackName = toStackName(ctx.projectName, targetName);
     const synthTemplatePath = path.join(assemblyDirectory, `${stackName}.template.json`);
 

src/cli/commands/import/import-runtime.ts

@@ -7,6 +7,7 @@ import { ExecLogger } from '../../logging';
 import { bootstrapEnvironment, buildCdkProject, checkBootstrapNeeded, synthesizeCdk } from '../../operations/deploy';
 import {
   copyAgentSource,
+  findResourceInDeployedState,
   parseAndValidateArn,
   resolveImportTarget,
   resolveProjectContext,
@@ -238,6 +239,20 @@ export async function handleImportRuntime(options: ImportResourceOptions): Promi
         logPath: logger.getRelativeLogPath(),
       };
     }
+    const targetName = target.name ?? 'default';
+    const existingResource = await findResourceInDeployedState(ctx.configIO, targetName, 'runtime', runtimeId);
+    if (existingResource) {
+      const error = `Runtime "${runtimeId}" is already imported in this project as "${existingResource}". Remove it first before re-importing.`;
+      logger.endStep('error', error);
+      logger.finalize(false);
+      return {
+        success: false,
+        error,
+        resourceType: 'runtime',
+        resourceName: localName,
+        logPath: logger.getRelativeLogPath(),
+      };
+    }
     logger.endStep('success');
 
     // 7. Copy source code
@@ -273,7 +288,6 @@ export async function handleImportRuntime(options: ImportResourceOptions): Promi
 
     const synthInfo = await toolkitWrapper.synth();
     const assemblyDirectory = synthInfo.assemblyDirectory;
-    const targetName = target.name ?? 'default';
     const stackName = toStackName(ctx.projectName, targetName);
     const synthTemplatePath = path.join(assemblyDirectory, `${stackName}.template.json`);
 

src/cli/commands/import/import-utils.ts

@@ -165,6 +165,33 @@ export function toStackName(projectName: string, targetName: string): string {
 // Deployed State Update
 // ============================================================================
 
+/**
+ * Check if a resource ID is already tracked in deployed-state.json for the given target.
+ * Returns the name it's tracked under, or undefined if not found.
+ */
+export async function findResourceInDeployedState(
+  configIO: ConfigIO,
+  targetName: string,
+  resourceType: 'runtime' | 'memory',
+  resourceId: string
+): Promise<string | undefined> {
+  /* eslint-disable @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-unsafe-argument, @typescript-eslint/no-explicit-any */
+  const state: any = await configIO.readDeployedState().catch(() => ({ targets: {} }));
+  const targetState = state.targets?.[targetName];
+  if (!targetState?.resources) return undefined;
+
+  const collection = resourceType === 'runtime' ? targetState.resources.runtimes : targetState.resources.memories;
+  if (!collection) return undefined;
+
+  for (const [name, entry] of Object.entries(collection)) {
+    const idField = resourceType === 'runtime' ? 'runtimeId' : 'memoryId';
+    if ((entry as any)[idField] === resourceId) return name;
+  }
+  /* eslint-enable @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-unsafe-argument, @typescript-eslint/no-explicit-any */
+
+  return undefined;
+}
+
 export interface ImportedResource {
   type: 'runtime' | 'memory';
   name: string;

src/cli/commands/import/phase2-import.ts

@@ -117,6 +117,18 @@ export async function executePhase2(options: Phase2Options): Promise<Phase2Resul
     return { success: true };
   } catch (err: unknown) {
     const message = err instanceof Error ? err.message : String(err);
+
+    // Detect "already exists in stack" errors and provide a friendlier message
+    const alreadyInStackMatch = /(.+) already exists in stack (.+)/.exec(message);
+    if (alreadyInStackMatch) {
+      const resourceId = alreadyInStackMatch[1];
+      const existingStack = alreadyInStackMatch[2];
+      return {
+        success: false,
+        error: `Resource "${resourceId}" is already managed by CloudFormation stack "${existingStack}". It must be removed from that stack before importing into this project.`,
+      };
+    }
+
     return { success: false, error: `Import change set failed: ${message}` };
   }
 }