feat: support the user_connections manifest feature

[WilliamBergamin]

Changelog

The features.user_connections app manifest property (is_enabled, auth_hosts) is now supported, so it is kept by run, deploy, and manifest sync.

Summary

The CLI decodes manifest.json (or the get-manifest hook output) into typed manifest structs, so any property it does not model is silently dropped before the manifest is sent to Slack. This adds features.user_connections to AppFeatures so apps that opt into the standardized user connection flow keep that setting.

Both fields are required by the manifest schema, so neither uses omitempty: a disabled feature ("is_enabled": false) keeps its auth_hosts, which is how the feature is meant to be turned off.

Preview

slack manifest info --source local with features.user_connections in manifest.json:

Before (main): the property is stripped

"features": {
  "app_home": {},
  "bot_user": { "display_name": "connector" }
}

After (this branch): the property round-trips

"features": {
  "app_home": {},
  "bot_user": { "display_name": "connector" },
  "user_connections": {
    "is_enabled": true,
    "auth_hosts": ["example.com", "auth.example.com"]
  }
}

Testing

• New cases in Test_AppManifest_AppFeatures for enabled and explicitly disabled user_connections.
• New Test_AppManifest_AppFeatures_UserConnections decodes manifest JSON, asserts the typed value, and checks it re-marshals unchanged (undefined, enabled, disabled with hosts).
• make test passes (lint: 0 issues).
• Manual: built main and this branch, ran slack manifest info --source local on a sample project with the property (output above).

Notes

• Follow-up: add user_connections to slackapi/manifest-schema so editors stop flagging it.
• Host format and item limits are validated by Slack's manifest API, like other manifest properties.

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.23%. Comparing base (eae9aad) to head (5cae797).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #688   +/-   ##
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  Coverage   78.23%   78.23%           
=======================================
  Files         239      239           
  Lines       18149    18149           
=======================================
  Hits        14199    14199           
  Misses       3950     3950           

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