fix(api): dispatch optional data-first calls

[lloydrichards]

Goal and scope

Restore the advertised data-first behavior for dual APIs with optional trailing arguments. Data-last calls must remain unchanged.

Description

Uses runtime input predicates for Box padding, borders, and Renderer helpers instead of treating optional arguments as required arity.

How to test

• Run bun run --cwd packages/effect-boxes test tests/optional-data-first.test.ts.
• Check omitted and supplied options in both data-first and piped forms.

Review

• Gatekeeping: Check correctness, tests, quality, and design before merge.
• Knowledge sharing: Quick intent and implementation review; light feedback is enough.
• Pair session: Review the remaining decisions together.

Closes #94

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
effect-boxes-docs	Ready	Preview	Sep 6, 2026 8:10am UTC

[changeset-bot]

🦋 Changeset detected

Latest commit: 38dfcbb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
effect-boxes	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[Copilot]

🟢 Approval recommended

The predicate-based dual dispatch fixes the reported runtime misbehavior and is backed by focused regression tests covering both data-first and data-last usage.

Pull request overview

Restores correct runtime behavior for Effect dual APIs when called data-first with omitted optional trailing arguments, aligning runtime return values with the published overloads for Box and Renderer.

Changes:

• Switch dual implementations for Box.border, Box.pad, Renderer.render, and Renderer.renderLinesToString from fixed arity to runtime input predicates to properly detect data-first calls.
• Add regression tests covering omitted/supplied options for both data-first and piped (data-last) forms.
• Add a patch changeset documenting the fix.

File summaries

File	Description
packages/effect-boxes/tests/optional-data-first.test.ts	Adds regression coverage for optional data-first calls and ensures data-last piping remains intact.
packages/effect-boxes/src/internal/renderer.ts	Updates dual dispatch for render and renderLinesToString to use runtime predicates.
packages/effect-boxes/src/internal/box.ts	Updates dual dispatch for border and pad to use runtime predicates.
.changeset/floppy-birds-battle.md	Documents the patch-level behavior fix for optional data-first calls.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 1
• Review effort level: Lite

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.