epicenter

Run a continuous collapse-and-simplify pass that surgically removes indirection failing to earn its boundary. Use when the user says 'collapse pass', 'simplify pass', 'reduce indirection', 'shrink the surface', 'find what to delete', when asking to audit a package for dead abstractions, when reviewing a pull request, branch, or recent merged change for simplification (isolated in a worktree), or when the goal is a sequence of small refactor commits that delete more than they add. Pairs with code-audit (smell catalog), refactoring (per-change mechanics), one-sentence-test (cohesion gate), cohesive-clean-breaks (deep redesigns), approachability-audit (first-read sanity), and post-implementation-review (second-read after each commit).

How a workspace-backed app under `apps/*` is composed: the isomorphic doc factory (`create<App>`), the environment factories (`open<App>Browser` / `open<App>Extension` / tauri), the `#platform/*` build-time platform DI for multi-platform (Tauri) apps, the `session` singleton, daemon/script placement under per-project `workspaces/<app>/`, and the file layout itself. Use when creating a new app, naming or placing the iso/browser/extension factory, wiring `#platform/*` subpath imports for a Tauri seam, choosing between auth-gated (Shape A) vs module-singleton (Shape B), placing the session singleton, or registering daemon/script bindings.

Query/RPC layer with TanStack Query, defineKeys, service composition, runtime DI. Use for createQuery, createMutation, queries/mutations, reactive data management.

TanStack AI patterns for @tanstack/ai, @tanstack/ai-svelte, chat state, streamed responses, UIMessage parts, tool calling, tool approvals, and provider model adapters. Use when working on AI chat, createChat, fetchServerSentEvents, UIMessage conversion, or TanStack AI tools.

Create a slash-command `/goal` for long-running Codex or Claude Code work when the user explicitly asks for a `/goal`, agent goal, or completion condition. Outputs one goal line with the objective, starting context, validation evidence, and stop condition.

List 3-5 comparable apps when planning a UX surface to test category fit and surface high-leverage refusals. Use for "what do other apps do", identity, sync state, local-first design.

Draft a self-contained, copy-pasteable prompt so a fresh agent can continue without this thread. Use when the user says "hand this off", "compact this", "wrap up for the next session", "write a continuation prompt", "draft a prompt", "make a prompt I can copy-paste", "create a delegation brief", or invokes /handoff.

Epicenter workspace API patterns: `defineTable`, `defineKv`, migrations, actions, `createWorkspace`, materializers, `openCollaboration`, and workspace connections. Use when editing workspace schemas, table/KV access, actions, attachments, or collaboration setup.

Epicenter auth packages: `@epicenter/auth` and the Svelte wrapper at `@epicenter/svelte/auth`, OAuth sessions, identity state, auth-owned fetch/WebSocket, and workspace lifecycle binding. Use when editing Epicenter auth clients, session state, hosted sign-in, or auth/workspace integration.

TypeScript project conventions: derived types, type placement, acronym casing, imports, generics, factories, and runtime schema patterns. Use when editing `.ts` files, defining exported types, reviewing type names, or organizing type tests.

Execute `specs/*.md` plans through working checkpoints. Use when the user says "execute this spec", "implement this plan", "run the spec", or points at a spec file.

Write technical specs that let agents implement autonomously. Use for "write a spec", "plan this feature", "create a planning doc".

Hub for the broad second-read pass after an implementation: list every touched file as an ASCII tree, mentally inline helpers, audit dead paths and stale imports, name invariant owners, sanity-check API shape and naming. Delegates to focused skills (collapse-pass, cohesive-clean-breaks, greenfield-clean-breaks, refactoring, code-audit, one-sentence-test, approachability-audit, testing, typescript, svelte, yjs). Use after finishing an implementation, before handoff, or when the user says 'review what you just did', 'second pass', 'final sweep'.

Arktype: runtime validation, discriminated unions with .merge()/.or(), spread keys. Use when mentioning arktype, type(), union types, command/event schemas.

Contract and invariants for `attach*` composition primitives in `packages/workspace` (side-effectful building blocks like attachIndexedDb, attachSqlite, attachBroadcastChannel, attachBunSqliteMaterializer, attachMarkdownMaterializer, openCollaboration), and when to use `create*` (pure construction) instead. Use when writing or reviewing an `attach*` or `create*` function, naming a new workspace primitive, composing inside a workspace builder, or deciding whether a primitive registers listeners at call time.

Error handling with wellcrafted trySync/tryAsync and toastOnError. Use for try-catch, Result types, error toasts, HTTP errors.

Draft and review durable GitHub pull request titles and bodies for Epicenter. Use when creating a PR, running gh pr create, drafting or editing a PR body, writing changelog entries, linking issues, choosing merge strategy, or reviewing PR text. For local commits and branches use the git skill; for issue replies use github-issues. Never include Testing, Test Plan, or Verification sections in PR bodies unless explicitly requested.

Factory function patterns to compose clients and services. Use when wrapping resources with domain methods or refactoring mixed client/service/method options.

Git commits and branches using Epicenter conventions. Use when staging files, writing commit messages, splitting commits, checking standalone commits, creating branches, or inspecting commit history. For pull request titles and bodies, use the pull-request skill.

Make commits reviewable and auditable as self-contained units, and order multi-file changes into atomic dependency-ordered waves. Use when planning commits, 'split this into commits', 'break this up', 'commit strategy', splitting work into waves, staging changes, reviewing branch history, or deciding whether a commit is too broad, too tiny, incomplete, or hard to revert.

Svelte 5 component and state-module patterns for Epicenter apps. Use when editing `.svelte`, `.svelte.ts`, or Svelte UI state code involving runes, `$props`, snippets, keyed lifecycles, `{#await}`, TanStack Query, SvelteMap, shadcn-svelte, or workspace observers.

Voice, tone, and punctuation rules for prose, UI text, tooltips, error messages, comments, JSDoc, markdown, commit messages, and docs. Use when: "fix the tone", "rewrite this", "sounds like AI", "sounds corporate", or deciding whether punctuation earns its emphasis.

First-read approachability lens. Read code as a newly onboarded TypeScript developer to surface indirection, misleading names, type-system-only tricks, and wrong-owner boundaries. Cited by post-implementation-review and collapse-pass as their readability pass; also use directly when code feels clever or hard to follow on first read.

Find the small product refusal that collapses a large implementation graph: refuse 10-20 percent of functionality to delete 80-90 percent of complexity. Use when the user says "asymmetric wins", "asymmetric win", "what can we refuse", "what collapses the most code", or when a design adds a fast path, fallback parser, provider-specific SDK, second transport, or compatibility alias beside a canonical path. Pairs with one-sentence-test (detects the opportunity) and cohesive-clean-breaks (executes the break).

Breaking-change and clean-break mechanics for decisions that change public shape, package boundaries, runtime contracts, naming, config structure, lifecycle ownership, or migration strategy: wave ordering, hybrid-API rejection, boundary movement, ownership tests, and deleting old paths instead of aliasing them. Use when proposing a breaking change, replacing an API, redesigning ownership, planning a multi-wave replacement, or deciding whether to keep both old and new paths alive. For the refuse-a-feature-to-collapse-complexity move on its own, use asymmetric-wins.

Fresh-context adversarial review for staged diffs, state machines, type shapes, lifecycle boundaries, and confusing abstractions. Use when the user says "fresh eyes", "grill this", "why not simpler", "state-machine audit", "does this type shape earn it", or asks for a new-developer review through a subagent. Compose with greenfield-clean-breaks only when compatibility pressure has been explicitly released.

Greenfield clean-break review for refusing compatibility, finding inconsistent ownership, and deleting unearned branches, fallback states, duplicate paths, and premature abstractions. Use when the user explicitly releases compatibility pressure with phrases like greenfield, no users, clean break, refuse compatibility, remove slop, or asks whether a system should be redesigned from the ideal shape.

Force one concrete sentence to find orphaned surfaces, duplicate verbs, inert abstractions. Use for "what does X do", "in one sentence", "too many options".

Use when a task seems trapped inside the current abstraction, an abstraction feels poorly designed, a fix keeps spreading across layers, or the user asks to think bigger, redesign from scratch, mentally inline, go up a level, or consider radical options. Forces a higher-level pass before coding: state the current path, invent the cleanest from-scratch option, inline suspicious layers, find asymmetric deletions, and choose the option that makes the system easiest to explain.

Create, revise, evaluate, and validate Vercel-backed Agent Skills for this repository. Use when writing a new skill, improving an existing skill, tuning skill descriptions, deciding what belongs in SKILL.md, references, scripts, or assets, validating discovery, or reviewing whether a skill should exist.

Technical articles and blog posts with honest trade-offs. Use when: "write a blog post", "draft an article", "write about this", creating articles in docs/articles/.

Review AGENTS.md, CLAUDE.md, and `.agents/skills` for instruction sprawl, duplicated guidance, routing overlap, and misplaced process detail. Use when adding or revising agent instructions, deciding whether a rule belongs globally or in a skill, grilling whether a new skill should exist, or cutting down skill complexity.

Epicenter UI component selection and composition patterns for Svelte apps using @epicenter/ui. Use when choosing or reviewing local UI components, loading or empty states, skeletons, spinners, command empty states, action pending UI, table/list no-row states, button or link tooltips, modal/dialog/sheet/drawer surfaces, package import boundaries, wrapper minimization, or replacing ad hoc UI such as Loading... text, custom loading dots, raw animate-pulse placeholders, raw tooltip wrappers, or one-off centered status markup.

Reap merged git worktrees and branches safely across the warp, codex, opencode, and conductor harnesses. Use when worktrees pile up, after a branch merges, when cleaning up `git worktree list`, removing an orphaned or detached worktree, or deciding whether a worktree is safe to delete. Not for creating branches or authoring commits (use the git skill).

Test file conventions: setup functions, factories, organization, type testing, naming, and pruning low-value tests. Use when: "write tests", "add a test", "fix this test", "delete tests", "prune tests", "audit tests", or modifying *.test.ts files.

Disciplined diagnosis loop for hard bugs and performance regressions. Reproduce → minimise → hypothesise → instrument → fix → regression-test. Use when user says "diagnose this" / "debug this", reports a bug, says something is broken/throwing/failing, or describes a performance regression.

Build a throwaway prototype to flesh out a design before committing to it. Routes between two branches: a runnable terminal app for state/business-logic questions, or several radically different UI variations toggleable from one route. Use when the user wants to prototype, sanity-check a data model or state machine, mock up a UI, explore design options, or says "prototype this", "let me play with it", "try a few designs".

Explain technical systems in a notebook style: short working notes, small code blocks, ASCII diagrams, concrete examples, and compressed rules. Use when the user asks to understand architecture, APIs, auth flows, specs, boundaries, code ownership, design tradeoffs, or says "zoom out", "give me the bigger picture", "what does this fit into", or "I'm lost in this file".

Scaffold Better Auth in TypeScript apps: framework handlers, DB adapters, OAuth, email/password, and auth UI. Use when adding login, sign-up, session handling, or Better Auth plugins.

Conversational PR-style summaries with visual diagrams. Use when: "can you summarize", "what happened", "where are we at", "give me an overview", "walk me through".