---
name: widen-return-type
description: widen return type
triggers:
  - widen return type
  - extensibility
  - overloads
  - opt-in tool map
  - feature flag gating
  - tool registration
generated_from_knowledge:
  - f4a42419-d0bc-4f80-8a52-eb44233aadb9
  - 15870ee2-0813-406f-afd6-f34a05343584
source_knowledge_ids:
  - f4a42419-d0bc-4f80-8a52-eb44233aadb9
  - 15870ee2-0813-406f-afd6-f34a05343584
generated_at: 2026-07-02T02:11:00.606Z
confidence: 0.60
status: active
version: 1
skill_origin: generated
---

<!-- generated by opencode-swarm skill-generator. Do not edit by hand; edits will be preserved on regeneration only with controlled update mode. -->

# widen return type

## Trigger

- widen return type
- extensibility
- overloads
- opt-in tool map
- feature flag gating
- tool registration

## Required Procedure

- use TypeScript overloads to preserve narrow return types when widening a function's return type for extensibility
- mirror existing opt-in pattern: separate tool map constant, conditional merge in agents/index.ts, gating tests verifying disabled and enabled states

## Forbidden Shortcuts

- invent new tool-gating mechanisms for opt-in feature flags

## Delegation Template

When delegating a task affected by this skill, include:

```
SKILLS: file:.opencode/skills/generated/widen-return-type/SKILL.md
```

## Reviewer Checks

- Verify each required action above appears in the diff.

## Source Knowledge IDs

- f4a42419-d0bc-4f80-8a52-eb44233aadb9 — When widening a function's return type (e.g. string instead of union) to support extensibility, use TypeScript overloads to preserve narrow types for known inputs — saves build-error round trips.
- 15870ee2-0813-406f-afd6-f34a05343584 — Pre-existing opt-in maps (memory, external_skills, skills) follow a consistent pattern — when implementing new gates, mirror the existing structure (separate SKILL_AGENT_TOOL_MAP, conditional merge in agents/index.ts) rather than inventing new mechanisms.</item>