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[api-extractor] Keep separate d.ts files but filter public API

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
node.js, typescript

Research direction

Start by reviewing API Extractor's reporting, rollups, and docs scenarios, especially dtsRollup, alongside TypeScript's per-module .d.ts output and the package.json exports mapping. Define how modules are crawled, public exports are filtered, and matching output files are generated. Done means separate non-empty .d.ts files preserve the source hierarchy, with discrepancies reported.

Written by the indexing model from the issue text.

Description

Summary

I'd like to use the API extractor functionalities to track my public API and filter anything non-public from my d.ts files.

At the same time I want to keep separate d.ts files (one for every .mjs just like typescript prints it).

Unfortunately the dtsRollup works in a "bundle/barrel module" mindset where you only have a single library file.

Details

In the era of ESM the practice of "bundling" when publishing packages seem to vanish to support features like tree-shaking better. Same applies for "barrel modules" which contain all exports of your library.

Following this strategy it would be great if api-extractor could do it's magic without expecting a single barrel d.ts.

Imagine a tsc output of .mjs and .d.ts files matching the .ts file hierarchy. I'd expect:

  1. api-extractor to crawl the modules of my project and build the public API surface.
  2. Potentially the exports property of the package.json is consulted to filter what's really public from an NPM perspective (mapping might be tricky though).
  3. api-extractor writes the output d.ts files with the same hierarchy to a given output directory (empty d.ts files are omitted).
  4. Any warnings on discrepancies of exports are reported (e.g. a public api exposes a filtered private one).

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question Answer
@microsoft/api-extractor version? 7.53.3
Operating system? Any
API Extractor scenario? reporting (.api.md) / rollups (.d.ts) / docs (.api.json)
Would you consider contributing a PR? Maybe, depends on the efforts
TypeScript compiler version? 5.9.3
Node.js version (node -v)? v24.11.0
Dominant language
TypeScript
Stars
6.5k
Forks
708
Avg merge
4d 13h
Merged PRs (30d)
62

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

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