Developer playground: genType support and sourcemap scaffolding

[fhammerschmidt]

This both adds a new tab to the developer playground for gentype (and the possibility to add it in the main playground) as well as a new tab and bi-directional highlighting for sourcemaps.

[fhammerschmidt]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. What shall we delve into next?

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[pkg-pr-new]

Open in StackBlitz

rescript

npm i https://pkg.pr.new/rescript-lang/rescript@8448

@rescript/belt

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/belt@8448

@rescript/darwin-arm64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/darwin-arm64@8448

@rescript/darwin-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/darwin-x64@8448

@rescript/linux-arm64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/linux-arm64@8448

@rescript/linux-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/linux-x64@8448

@rescript/runtime

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/runtime@8448

@rescript/win32-x64

npm i https://pkg.pr.new/rescript-lang/rescript/@rescript/win32-x64@8448

commit: bf0ce1e

[github-actions]

Developer playground preview: https://rescript-lang.github.io/rescript/dev-playground/?version=pr-8448

[fhammerschmidt]

@codex review

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-30T21:00:32.648422Z	919658a	Manual request

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review" or "@codex security review".

Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings.

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: 919658a8f0

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[codecov]

Codecov Report

❌ Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.44%. Comparing base (59372ec) to head (bf0ce1e).

Files with missing lines	Patch %	Lines
compiler/core/js_source_map.ml	57.14%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8448      +/-   ##
==========================================
- Coverage   76.44%   76.44%   -0.01%     
==========================================
  Files         478      478              
  Lines       63163    63168       +5     
==========================================
+ Hits        48286    48289       +3     
- Misses      14877    14879       +2     

Files with missing lines	Coverage Δ
compiler/core/lam_compile_main.ml	89.17% <ø> (ø)
compiler/core/js_source_map.ml	79.85% <57.14%> (-0.77%)	⬇️

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.