fix: Improve ESM compatibility for named exports

[grantjoy]

Summary

This PR fixes ESM interoperability issues where named exports (particularly ExpressReceiver, SocketModeReceiver, HTTPReceiver, and AwsLambdaReceiver) weren't accessible when importing from ESM, as identified by @arethetypeswrong/cli.

Problem

The current export pattern:

export { default as ExpressReceiver, ExpressReceiverOptions } from './receivers/ExpressReceiver';

Generates CommonJS code like:

Object.defineProperty(exports, "ExpressReceiver", { 
  enumerable: true, 
  get: function () { return __importDefault(ExpressReceiver_1).default; } 
});

This dynamic property access pattern isn't statically analyzable by Node.js's ESM-CJS interop layer, so these exports don't get exposed when importing from ESM:

// ❌ Before: undefined when imported from ESM
import { ExpressReceiver } from '@slack/bolt';

Solution

Refactored to use an import-then-export pattern:

import ExpressReceiver from './receivers/ExpressReceiver';
export { ExpressReceiver };
export type { ExpressReceiverOptions } from './receivers/ExpressReceiver';

This generates simpler, statically analyzable CommonJS code that Node.js can properly expose as named exports in ESM.

Additionally:

• Separated type-only exports using export type for better tree-shaking
• Fixed Logger and OAuth type re-exports to be type-only (they're interfaces, not runtime values)

Verification

Before:

$ bunx @arethetypeswrong/cli --from-npm @slack/bolt -f json

{
  "problems": {
    "NamedExports": [
      {
        "missing": [
          "Logger",
          "ExpressReceiver",
          "SocketModeReceiver",
          "HTTPReceiver",
          "AwsLambdaReceiver",
          "Installation",
          "InstallURLOptions",
          "InstallationQuery",
          "InstallationStore",
          "StateStore",
          "InstallProviderOptions"
        ]
      }
    ]
  }
}

After:

$ bunx @arethetypeswrong/cli --pack . -f json

{
  "problems": {}
}

✅ All NamedExports issues resolved!

ESM Import Test:

import { ExpressReceiver, App } from '@slack/bolt';
console.log(typeof ExpressReceiver); // ✅ "function" (was "undefined")
console.log(typeof App); // ✅ "function"

CommonJS Compatibility:

const { ExpressReceiver, App } = require('@slack/bolt');
console.log(typeof ExpressReceiver); // ✅ "function"
console.log(typeof App); // ✅ "function"

Tests

All existing tests pass:

94.52% code coverage

Related Issues

• Closes Why Common JS and not ESM? #2565
• Related to fix: better ES module support for App class #2632
• Related to Removing support for Node 18 and other upcoming breaking changes #2644

Migration Guide

This change is fully backward compatible. No code changes required for consumers.

Both import styles continue to work:

// ✅ Works before and after
import { App } from '@slack/bolt';

// ✅ Now works with ESM (was broken before)
import { ExpressReceiver } from '@slack/bolt';

[salesforce-cla]

Thanks for the contribution! Before we can merge this, we need @grantjoy to sign the Salesforce Inc. Contributor License Agreement.

[mwbrooks]

Hi @grantjoy 👋🏻 Thanks for taking the time to craft an in-depth and quality pull request! 👌🏻

The PR looks safe to run our GitHub Workflows, so I've approved it. It looks like there are some minor failures due to biomjs formatting:

> @slack/[email protected] lint
> npx @biomejs/biome check docs src test examples

src/index.ts format ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Formatter would have printed the following content:
  
    94 94 │   export * as webApi from '@slack/web-api';
Checked 121 files in 202ms. No fixes applied.
Found 1 error.
    95 95 │   
    96    │ - 

❓ When you have a moment, would you mind pushing a commit to fix the formatting error? It looks like the newline on L95 should be removed.

🔍 I'll ping a few teammates to look over your pull request, but on first review it's look good to move forward! 👍🏻

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.44%. Comparing base (716a207) to head (6158b4c).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2724   +/-   ##
=======================================
  Coverage   93.44%   93.44%           
=======================================
  Files          37       37           
  Lines        7675     7675           
  Branches      669      669           
=======================================
  Hits         7172     7172           
  Misses        498      498           
  Partials        5        5           

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[zimeg]

@grantjoy LGTM! Thanks for bringing this enhancement to exports - I agree this is a nice pattern to use 🙏 ✨