[H1][TS-STANDARDS]

Dictum: Consolidation-first, polymorphic TypeScript. Effect orchestrates; domain computes.

Write dense, integrated modules with minimal public APIs. Prefer capability facades, command algebras, and auto-registration over helper proliferation and manual wiring.

Tasks:

1. Read index.md.
2. Read references/snippets.md first.
3. Read domain references as needed: consolidation.md, composition.md, adts-and-matching.md, errors-and-services.md, repo-conventions.md.
4. Implement by reusing canonical snippet IDs (SNIP-*) instead of inventing new patterns.
5. Run validator: bash ./.claude/skills/ts-standards/scripts/validate-ts-standards.sh --mode check.
6. Validate against [VERIFY] checklist.

Versions: TypeScript 6.0-dev, Effect 3.19+, React 19, Vite 7.

[1][WORKFLOW]

Dictum: Snippet-first workflow prevents style drift and file bloat.

1. Select target behavior and public surface.
2. Route to snippet IDs from references/snippets.md.
3. Compose in this order: command algebra -> service surface -> layer integration -> boundary mapping.
4. Keep internal symbols internal; integrate via registry/layer composition.
5. Run policy validator and fix violations before final output.

[2][CORE_POLICY]

Dictum: Few powerful interfaces beat many narrow functions.

• Hard-minimal public APIs -- stable capability entrypoints only.
• Auto-integration by default -- new internal logic becomes active via registration, not extra exports.
• Polymorphism over proliferation -- one command/config function replaces clusters of near-duplicate methods.
• Exhaustive branching -- closed variants require Match.exhaustive.
• Schema-derived types only -- no parallel manual types.

[3][NON_NEGOTIABLES]

Dictum: Compiler-visible constraints remove ambiguity.

[IMPORTANT]:

• [ALWAYS] Prefix private/internal symbols with _.
• [ALWAYS] Gather public exports in final [EXPORT] section.
• [ALWAYS] Use Effect.Service for services and Effect.fn('Service.method') for methods.
• [ALWAYS] Reuse snippet IDs for shared patterns before authoring new variants.
• [ALWAYS] Keep each file in this skill directory at <=275 LOC.

[CRITICAL]:

• [NEVER] any, let, var, for, while, try/catch, default exports (except config files).
• [NEVER] if (...) statements in TypeScript policy scope.
• [NEVER] Effect.if(...).
• [NEVER] Helper/utility file sprawl (helpers.ts, utils.ts, thin wrappers).
• [NEVER] Export _-prefixed symbols.
• [NEVER] Widen package export surface without explicit policy update.

[4][PUBLIC_SURFACE_POLICY]

Dictum: Packages expose capabilities, not internals.

Server allowed exports:

• ./api
• ./runtime
• ./errors
• ./testing

Database allowed exports:

• ./runtime
• ./models
• ./migrator
• ./testing

Everything else is internal-by-default and consumed via internal composition.

[5][SNIPPET_ROUTING]

Dictum: Use canonical snippets as stable building blocks.

[REFERENCE] Canonical code snippets: references/snippets.md

[6][VALIDATION]

Dictum: Automated gates enforce consistency at scale.

[FILE_LAYOUT]: Types -> Schema -> Constants -> Errors -> Services -> Functions -> Layers -> Export.

[VERIFY]:

• No forbidden syntax (any, let/var, loops, try/catch, default exports, inline export style violations).
• No if (...) and no Effect.if(...).
• No exported _-prefixed symbols.
• Public export map complies with hard-minimal policy.
• Deep imports from server/database follow approved allowlist.
• All files under /.claude/skills/ts-standards/ are <=275 LOC.
• Snippet-first reuse applied before adding custom variants.

Commands:

• bash ./.claude/skills/ts-standards/scripts/validate-ts-standards.sh --mode check
• pnpm run check:ts-standards

[REFERENCE] Script: scripts/validate-ts-standards.sh