fix(writer): don't splice import type { as a Python simple import

src/engine/writer.ts

@@ -36,7 +36,13 @@ export async function writeFiles(
   outputDir: string,
   options?: WriteOptions,
 ): Promise<WriteResult> {
-  const result: WriteResult = { written: [], merged: [], skipped: [], identical: [], ignored: [] };
+  const result: WriteResult = {
+    written: [],
+    merged: [],
+    skipped: [],
+    identical: [],
+    ignored: [],
+  };
   const sorted = [...files].sort((a, b) => a.path.localeCompare(b.path));
   const language = options?.language;
   const header = options?.header ?? '';
@@ -275,7 +281,11 @@ export async function overwriteWithPreservedRegions(
   //     a class matching one in the generated content.
   const replacedClasses = new Set<string>();
   const handledBlockKeys = new Set<string>();
-  const replacements: { startLine: number; endLine: number; content: string[] }[] = [];
+  const replacements: {
+    startLine: number;
+    endLine: number;
+    content: string[];
+  }[] = [];
   for (const [className, classBlocks] of blocksByClass) {
     // Determine the target class for replacement.  When the block has a
     // containing class, we check if the block redefines that class.  When
@@ -544,8 +554,10 @@ function collectTsImports(lines: string[]): TsImports {
  */
 function spliceExtraImports(existingLines: string[], resultLines: string[]): void {
   // Python-style `import hashlib`. Excludes TS forms like `import X from '…'`
-  // which have a `from` clause and are handled by the TS collector below.
-  const isPythonSimpleImport = (l: string) => /^import\s+\w/.test(l) && !/\sfrom\s/.test(l);
+  // (have a `from` clause) and TS multi-line type imports whose first line is
+  // `import type {` (have a brace) — both are handled by the TS collector
+  // below.
+  const isPythonSimpleImport = (l: string) => /^import\s+\w/.test(l) && !/\sfrom\s/.test(l) && !/[{}]/.test(l);
 
   // Simple imports (import hashlib, import json, …)
   const existingSimple = new Set(existingLines.filter(isPythonSimpleImport).map((l) => l.trim()));

test/engine/writer-ignore.test.ts

@@ -14,7 +14,12 @@ describe('@oagen-ignore-file', () => {
       await fs.writeFile(filePath, '// @oagen-ignore-file\nexport class Client {}', 'utf-8');
 
       const result = await writeFiles(
-        [{ path: 'client.ts', content: 'export class Client { newMethod() {} }' }],
+        [
+          {
+            path: 'client.ts',
+            content: 'export class Client { newMethod() {} }',
+          },
+        ],
         tmpDir,
         { language: 'node', header },
       );
@@ -31,7 +36,12 @@ describe('@oagen-ignore-file', () => {
     const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'oagen-test-'));
     try {
       const result = await writeFiles(
-        [{ path: 'client.ts', content: '// @oagen-ignore-file\nexport class Client {}' }],
+        [
+          {
+            path: 'client.ts',
+            content: '// @oagen-ignore-file\nexport class Client {}',
+          },
+        ],
         tmpDir,
         { language: 'node', header },
       );
@@ -51,7 +61,10 @@ describe('@oagen-ignore-file', () => {
 
       const result = await writeFiles(
         [
-          { path: 'ignored.ts', content: 'export class Ignored { updated() {} }' },
+          {
+            path: 'ignored.ts',
+            content: 'export class Ignored { updated() {} }',
+          },
           { path: 'normal.ts', content: 'export class Normal {}' },
         ],
         tmpDir,
@@ -607,4 +620,42 @@ describe('@oagen-ignore-start/end with overwriteExisting', () => {
       await fs.rm(tmpDir, { recursive: true });
     }
   });
+
+  it('does not splice `import type {` as a Python simple import when existing has multi-line TS type imports', async () => {
+    // Regression: the Python simple-import detector matched the first line
+    // of a multi-line TS `import type { … }` block (`import type {`), so the
+    // bare opener got spliced into the result as if it were a `import json`
+    // line. Result: a stranded `import type {` orphan before the value
+    // imports, breaking TypeScript parsing.
+    const existing = [
+      "import type { WorkOS } from '../workos';",
+      'import type {',
+      '  WebhookEndpoint,',
+      '  WebhookEndpointResponse,',
+      "} from './interfaces/webhook-endpoint.interface';",
+      "import { deserializeEvent } from '../common/serializers';",
+      '',
+      'export class Webhooks {',
+      '  // @oagen-ignore-start',
+      '  hand() { deserializeEvent({} as any); }',
+      '  // @oagen-ignore-end',
+      '}',
+    ].join('\n');
+
+    const generated = [
+      "import type { WorkOS } from '../workos';",
+      "import type { WebhookEndpoint, WebhookEndpointResponse } from './interfaces/webhook-endpoint.interface';",
+      '',
+      'export class Webhooks {',
+      '  list() { return [] as WebhookEndpoint[]; }',
+      '}',
+    ].join('\n');
+
+    const result = await overwriteWithPreservedRegions(existing, generated, 'node');
+
+    // The bare `import type {` from existing must NOT appear in the result.
+    expect(result).not.toMatch(/^\s*import type \{\s*$/m);
+    // The hand-written value import survives, on its own line.
+    expect(result).toContain("import { deserializeEvent } from '../common/serializers';");
+  });
 });