[api-extractor] Report unresolvable inline import paths in .d.ts rollups

apps/api-extractor/src/api/ExtractorMessageId.ts

@@ -117,7 +117,12 @@ export enum ExtractorMessageId {
   MissingGetter = 'ae-missing-getter',
 
   /**
-   * "Incorrect file type; API Extractor expects to analyze compiler outputs with the .d.ts file extension.
+   * "The inline import path ___ cannot be resolved in the .d.ts rollup, because the rollup does not
+   * preserve the original file layout."
+   */
+  UnresolvedImportPath = 'ae-unresolved-import-path',
+
+ to analyze compiler outputs with the .d.ts file extension.
    * Troubleshooting tips: `https://api-extractor.com/link/dts-error`"
    */
   WrongInputFileType = 'ae-wrong-input-file-type'
@@ -141,5 +146,6 @@ export const allExtractorMessageIds: Set<string> = new Set<string>([
   'ae-unresolved-link',
   'ae-setter-with-docs',
   'ae-missing-getter',
+  'ae-unresolved-import-path',
   'ae-wrong-input-file-type'
 ]);

apps/api-extractor/src/generators/DtsEmitHelpers.ts

@@ -13,6 +13,7 @@ import type { Span } from '../analyzer/Span';
 import type { IndentedWriter } from './IndentedWriter';
 import { SourceFileLocationFormatter } from '../analyzer/SourceFileLocationFormatter';
 import { TypeScriptHelpers } from '../analyzer/TypeScriptHelpers';
+import { ExtractorMessageId } from '../api/ExtractorMessageId';
 
 /**
  * Some common code shared between DtsRollupGenerator and ApiReportGenerator.
@@ -170,6 +171,20 @@ export class DtsEmitHelpers {
         span.modification.skipAll();
         span.modification.prefix = `${referencedEntity.nameForEmit}${typeArgumentsText}${separatorAfter}`;
       }
+    } else if (ts.isLiteralTypeNode(node.argument) && ts.isStringLiteral(node.argument.literal)) {
+      // The import was not resolved to a rolled up entity, so its span gets emitted verbatim. A relative
+      // path is meaningless in the rollup, which does not preserve the original file layout, so the
+      // emitted .d.ts would not compile. Report that instead of leaving the user to discover it later.
+      const modulePath: string = node.argument.literal.text;
+      if (modulePath.startsWith('.')) {
+        collector.messageRouter.addAnalyzerIssue(
+          ExtractorMessageId.UnresolvedImportPath,
+          `The inline import path "${modulePath}" could not be resolved, so it would be emitted unchanged` +
+            ` into the .d.ts rollup, where it does not resolve to anything. Import the symbol at the top` +
+            ` of the file instead of using an inline import() type.`,
+          astDeclaration
+        );
+      }
     }
   }
 

common/changes/@microsoft/api-extractor/fix-api-extractor-relative-import-path_2026-08-17-06-54-27.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "comment": "Report a new `ae-unresolved-import-path` message when an inline `import()` type with a relative path cannot be resolved, instead of silently emitting the unusable path into the .d.ts rollup.",
+      "type": "minor",
+      "packageName": "@microsoft/api-extractor"
+    }
+  ],
+  "packageName": "@microsoft/api-extractor"
+}

common/reviews/api/api-extractor.api.md

@@ -158,6 +158,7 @@ export enum ExtractorMessageId {
     PreapprovedUnsupportedType = "ae-preapproved-unsupported-type",
     SetterWithDocs = "ae-setter-with-docs",
     Undocumented = "ae-undocumented",
+    UnresolvedImportPath = "ae-unresolved-import-path",
     UnresolvedInheritDocBase = "ae-unresolved-inheritdoc-base",
     UnresolvedInheritDocReference = "ae-unresolved-inheritdoc-reference",
     UnresolvedLink = "ae-unresolved-link",