# 3. Unified `skills/shared/` for Claude Code + Copilot CLI

**Status:** Accepted · 2026-04 (v3.5.0) · Amended 2026-04 (v5.3.3 - internal `core/external/` split, install destination unchanged)

## Context

Up through v3.4, skills were split into `pipeline/skills/claude/` (84 iOS-only)
and `pipeline/skills/copilot/` (60 Android/web + pipeline). Zero overlap.
Consequences:

- Claude users could not invoke `multi-agent-*` pipeline skills (they were
  Copilot-only).
- Copilot users couldn't access iOS/SwiftUI guidance.
- Two directories meant two places to add or update a skill - drift was
  inevitable, and unnoticed.
- README claim "145 skills" was not accurate for either CLI.

## Decision

Collapse both directories into `pipeline/skills/shared/`. Installer copies
the same set to both `~/.claude/skills/` and `~/.copilot/skills/`. Both CLIs
now ship with identical skill coverage (145 skills as of 3.5.0).

Fifteen loose `*.md` files that were in the old copilot tree were normalized
to the canonical `folder/SKILL.md` shape.

## Consequences

Positive:

- Downloaders get the same capability regardless of which CLI flag they
  installed with.
- Adding a skill is now a single write.
- Skill index (`pipeline/skills/shared/README.md`) auto-generates from a
  single source.
- Unblocks the 4.0 single-source-for-commands-and-skills plan - same
  directory structure, just needs content unification.

Negative:

- Disk footprint per install is ~1.5× larger than before for users who
  only wanted iOS or only wanted web.
- Some iOS skills are noise for backend-only users and vice versa.
  Mitigated by the categorized index - easy to browse and ignore.

## Alternatives Considered

**Keep two directories, add symlinks / install-time copy:** would have fixed
the drift-risk but not the "which CLI gets what" asymmetry in the source.
Hidden complexity.

**Per-stack skill packs (`skills/ios/`, `skills/android/`, ...) with
install-time filter:** tempting. Rejected for 3.5.0 because the install-time
filter would need a stack detector exact enough to not exclude relevant
cross-cutting skills. Revisit for 4.0.