chore: add agent skills for Svelte 5, SvelteKit, TypeScript, and Drizzle

Install project-level skills via skills.sh CLI:
- svelte5-best-practices (runes, snippets, events, migration)
- sveltekit-structure (routing, layouts, error boundaries)
- sveltekit-data-flow (load functions, form actions, serialization)
- typescript-best-practices (type-first development, discriminated unions)
- drizzle-migrations (SQLite schema, query patterns)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.agents/skills/drizzle-migrations/SKILL.md

@@ -0,0 +1,423 @@
+---
+name: drizzle-migrations
+description: Drizzle ORM schema management and SQLite migrations — adding tables, modifying columns, creating indexes, generating and running migrations, Drizzle query patterns. NOT for Prisma, TypeORM,
+  Sequelize, or raw SQL migration tools.
+allowed-tools: Read,Write,Edit,Bash(npm:*,npx:*)
+metadata:
+  category: Data & Analytics
+  tags:
+  - database
+  - drizzle
+  - migrations
+  pairs-with:
+  - skill: database-design-patterns
+    reason: Schema migration implementation follows database design pattern decisions
+  - skill: supabase-admin
+    reason: Drizzle migrations run against Supabase PostgreSQL databases with RLS considerations
+  - skill: fullstack-debugger
+    reason: Migration failures and schema mismatches are common fullstack debugging scenarios
+---
+
+# Drizzle ORM Migrations
+
+This skill helps you manage database schema changes using Drizzle ORM with SQLite.
+
+## When to Use
+
+✅ **USE this skill for:**
+- Adding new tables or modifying existing columns
+- Generating and running database migrations
+- Drizzle-specific query patterns and relations
+- SQLite schema best practices with Drizzle
+- Setting up Drizzle configuration
+
+❌ **DO NOT use for:**
+- Supabase/PostgreSQL → use `supabase-admin` skill
+- Raw SQL without Drizzle → use standard SQL resources
+- Prisma ORM → different syntax and patterns
+- General database design theory → use database architecture resources
+
+## Project Setup
+
+**Configuration**: `drizzle.config.ts`
+```typescript
+import { defineConfig } from 'drizzle-kit';
+
+export default defineConfig({
+  schema: './src/db/schema.ts',
+  out: './drizzle',
+  dialect: 'sqlite',
+  dbCredentials: {
+    url: './data/app.db',
+  },
+});
+```
+
+**Commands**:
+```bash
+npm run db:generate  # Generate migration files
+npm run db:push      # Push schema directly (dev only)
+npm run db:studio    # Open Drizzle Studio GUI
+```
+
+## Schema Definition
+
+Location: `src/db/schema.ts`
+
+### Table Definition
+
+```typescript
+import { sqliteTable, text, integer, real, blob } from 'drizzle-orm/sqlite-core';
+import { relations } from 'drizzle-orm';
+
+// Basic table
+export const users = sqliteTable('users', {
+  id: text('id').primaryKey(),
+  email: text('email').notNull().unique(),
+  username: text('username').notNull(),
+  passwordHash: text('password_hash'),
+  createdAt: text('created_at').notNull().default(sql`CURRENT_TIMESTAMP`),
+  updatedAt: text('updated_at'),
+});
+
+// Table with foreign key
+export const checkIns = sqliteTable('check_ins', {
+  id: text('id').primaryKey(),
+  userId: text('user_id').notNull().references(() => users.id, {
+    onDelete: 'cascade',
+  }),
+  mood: integer('mood').notNull(),
+  cravingLevel: integer('craving_level').notNull(),
+  sleepHours: real('sleep_hours'),
+  notes: text('notes'),
+  createdAt: text('created_at').notNull().default(sql`CURRENT_TIMESTAMP`),
+});
+
+// Table with composite index
+export const auditLog = sqliteTable('audit_log', {
+  id: text('id').primaryKey(),
+  userId: text('user_id').notNull(),
+  action: text('action').notNull(),
+  targetType: text('target_type'),
+  targetId: text('target_id'),
+  details: text('details'),  // JSON string
+  createdAt: text('created_at').notNull().default(sql`CURRENT_TIMESTAMP`),
+}, (table) => ({
+  userActionIdx: index('idx_audit_user_action').on(table.userId, table.action),
+  createdAtIdx: index('idx_audit_created').on(table.createdAt),
+}));
+```
+
+### Relations
+
+```typescript
+export const usersRelations = relations(users, ({ many }) => ({
+  checkIns: many(checkIns),
+  sessions: many(sessions),
+  journalEntries: many(journalEntries),
+}));
+
+export const checkInsRelations = relations(checkIns, ({ one }) => ({
+  user: one(users, {
+    fields: [checkIns.userId],
+    references: [users.id],
+  }),
+}));
+```
+
+## Column Types
+
+### SQLite Types in Drizzle
+
+```typescript
+import {
+  sqliteTable,
+  text,           // TEXT - strings, JSON, dates
+  integer,        // INTEGER - numbers, booleans (0/1)
+  real,           // REAL - floating point
+  blob,           // BLOB - binary data
+} from 'drizzle-orm/sqlite-core';
+
+const examples = sqliteTable('examples', {
+  // Strings
+  name: text('name').notNull(),
+  description: text('description'),
+
+  // Numbers
+  count: integer('count').notNull().default(0),
+  rating: real('rating'),
+
+  // Booleans (stored as 0/1)
+  isActive: integer('is_active', { mode: 'boolean' }).default(true),
+
+  // Dates (stored as ISO strings)
+  createdAt: text('created_at').notNull().default(sql`CURRENT_TIMESTAMP`),
+  expiresAt: text('expires_at'),
+
+  // JSON (stored as TEXT)
+  metadata: text('metadata', { mode: 'json' }),
+
+  // Enums (stored as TEXT)
+  status: text('status', { enum: ['pending', 'active', 'archived'] }),
+});
+```
+
+## Migration Strategies
+
+### Strategy 1: Push (Development Only)
+
+```bash
+npm run db:push
+```
+
+- Directly applies schema changes
+- Fast for development
+- **Never use in production**
+
+### Strategy 2: Generate & Migrate (Production)
+
+```bash
+# 1. Generate migration file
+npm run db:generate
+
+# 2. Review generated SQL in /drizzle folder
+
+# 3. Apply migration (in code or manually)
+```
+
+### Applying Migrations in Code
+
+```typescript
+import { drizzle } from 'drizzle-orm/better-sqlite3';
+import { migrate } from 'drizzle-orm/better-sqlite3/migrator';
+import Database from 'better-sqlite3';
+
+const sqlite = new Database('./data/app.db');
+const db = drizzle(sqlite);
+
+// Run migrations
+migrate(db, { migrationsFolder: './drizzle' });
+```
+
+## Common Schema Changes
+
+### Adding a New Table
+
+```typescript
+// 1. Add to schema.ts
+export const newFeature = sqliteTable('new_feature', {
+  id: text('id').primaryKey(),
+  userId: text('user_id').notNull().references(() => users.id),
+  name: text('name').notNull(),
+  createdAt: text('created_at').notNull().default(sql`CURRENT_TIMESTAMP`),
+});
+
+// 2. Add relations
+export const newFeatureRelations = relations(newFeature, ({ one }) => ({
+  user: one(users, {
+    fields: [newFeature.userId],
+    references: [users.id],
+  }),
+}));
+
+// 3. Generate migration
+// npm run db:generate
+```
+
+### Adding a Column
+
+```typescript
+// In schema.ts, add the new column
+export const users = sqliteTable('users', {
+  // existing columns...
+  newColumn: text('new_column'),  // Add this
+});
+
+// Generate migration
+// npm run db:generate
+```
+
+### Adding an Index
+
+```typescript
+export const messages = sqliteTable('messages', {
+  id: text('id').primaryKey(),
+  conversationId: text('conversation_id').notNull(),
+  createdAt: text('created_at').notNull(),
+}, (table) => ({
+  // Add index
+  convCreatedIdx: index('idx_messages_conv_created')
+    .on(table.conversationId, table.createdAt),
+}));
+```
+
+### Renaming (Requires Manual SQL)
+
+SQLite doesn't support direct column renames in older versions. For complex changes:
+
+```sql
+-- drizzle/XXXX_rename_column.sql
+-- Manual migration for column rename
+
+-- 1. Create new table with desired schema
+CREATE TABLE users_new (
+  id TEXT PRIMARY KEY,
+  email TEXT NOT NULL UNIQUE,
+  display_name TEXT NOT NULL,  -- renamed from username
+  created_at TEXT NOT NULL
+);
+
+-- 2. Copy data
+INSERT INTO users_new SELECT id, email, username, created_at FROM users;
+
+-- 3. Drop old table
+DROP TABLE users;
+
+-- 4. Rename new table
+ALTER TABLE users_new RENAME TO users;
+```
+
+## Query Patterns
+
+### Basic Queries
+
+```typescript
+import { db } from '@/db';
+import { eq, and, or, desc, asc, like, gte, lte } from 'drizzle-orm';
+import { users, checkIns } from '@/db/schema';
+
+// Select all
+const allUsers = await db.select().from(users);
+
+// Select with conditions
+const activeUsers = await db
+  .select()
+  .from(users)
+  .where(eq(users.isActive, true));
+
+// Select specific columns
+const userEmails = await db
+  .select({ id: users.id, email: users.email })
+  .from(users);
+
+// Complex where clause
+const results = await db
+  .select()
+  .from(checkIns)
+  .where(
+    and(
+      eq(checkIns.userId, userId),
+      gte(checkIns.createdAt, startDate),
+      lte(checkIns.createdAt, endDate)
+    )
+  )
+  .orderBy(desc(checkIns.createdAt))
+  .limit(30);
+```
+
+### Insert
+
+```typescript
+// Single insert
+const [newUser] = await db
+  .insert(users)
+  .values({
+    id: generateId(),
+    email: 'user@example.com',
+    username: 'newuser',
+  })
+  .returning();
+
+// Bulk insert
+await db.insert(checkIns).values([
+  { id: '1', userId, mood: 7, cravingLevel: 2 },
+  { id: '2', userId, mood: 8, cravingLevel: 1 },
+]);
+
+// Upsert (insert or update)
+await db
+  .insert(users)
+  .values({ id: 'user-1', email: 'new@example.com' })
+  .onConflictDoUpdate({
+    target: users.id,
+    set: { email: 'new@example.com' },
+  });
+```
+
+### Update
+
+```typescript
+await db
+  .update(users)
+  .set({ username: 'newname', updatedAt: new Date().toISOString() })
+  .where(eq(users.id, userId));
+```
+
+### Delete
+
+```typescript
+// Always use WHERE clause!
+await db
+  .delete(checkIns)
+  .where(eq(checkIns.id, checkInId));
+
+// Delete with multiple conditions
+await db
+  .delete(sessions)
+  .where(
+    and(
+      eq(sessions.userId, userId),
+      lte(sessions.expiresAt, new Date().toISOString())
+    )
+  );
+```
+
+### Joins
+
+```typescript
+const userWithCheckIns = await db
+  .select({
+    user: users,
+    checkIn: checkIns,
+  })
+  .from(users)
+  .leftJoin(checkIns, eq(users.id, checkIns.userId))
+  .where(eq(users.id, userId));
+```
+
+### Aggregations
+
+```typescript
+import { count, avg, sum, max, min } from 'drizzle-orm';
+
+const stats = await db
+  .select({
+    totalCheckIns: count(),
+    avgMood: avg(checkIns.mood),
+    maxStreak: max(checkIns.streak),
+  })
+  .from(checkIns)
+  .where(eq(checkIns.userId, userId));
+```
+
+## Best Practices
+
+1. **Always use transactions for related changes**
+```typescript
+await db.transaction(async (tx) => {
+  await tx.insert(users).values(userData);
+  await tx.insert(profiles).values(profileData);
+});
+```
+
+2. **Always include WHERE on DELETE/UPDATE**
+3. **Use indexes for frequently queried columns**
+4. **Store dates as ISO strings for SQLite**
+5. **Use `returning()` to get inserted/updated rows**
+6. **Generate migrations, don't push to production**
+
+## References
+
+- [Drizzle ORM Docs](https://orm.drizzle.team/docs/overview)
+- [Drizzle SQLite](https://orm.drizzle.team/docs/get-started-sqlite)
+- [Drizzle Migrations](https://orm.drizzle.team/docs/migrations)

.agents/skills/svelte5-best-practices/SKILL.md

@@ -0,0 +1,81 @@
+---
+name: svelte5-best-practices
+description: "Svelte 5 runes, snippets, SvelteKit patterns, and modern best practices for TypeScript and component development. Use when writing, reviewing, or refactoring Svelte 5 components and SvelteKit applications. Triggers on: Svelte components, runes ($state, $derived, $effect, $props, $bindable, $inspect), snippets ({#snippet}, {@render}), event handling, SvelteKit data loading, form actions, Svelte 4 to Svelte 5 migration, store to rune migration, slots to snippets migration, TypeScript props typing, generic components, SSR state isolation, performance optimization, or component testing."
+license: MIT
+metadata:
+  author: ejirocodes
+  version: '1.0.0'
+---
+
+# Svelte 5 Best Practices
+
+## Quick Reference
+
+| Topic | When to Use | Reference |
+|-------|-------------|-----------|
+| **Runes** | $state, $derived, $effect, $props, $bindable, $inspect | [runes.md](references/runes.md) |
+| **Snippets** | Replacing slots, {#snippet}, {@render} | [snippets.md](references/snippets.md) |
+| **Events** | onclick handlers, callback props, context API | [events.md](references/events.md) |
+| **TypeScript** | Props typing, generic components | [typescript.md](references/typescript.md) |
+| **Migration** | Svelte 4 to 5, stores to runes | [migration.md](references/migration.md) |
+| **SvelteKit** | Load functions, form actions, SSR, page typing | [sveltekit.md](references/sveltekit.md) |
+| **Performance** | Universal reactivity, avoiding over-reactivity, streaming | [performance.md](references/performance.md) |
+
+## Essential Patterns
+
+### Reactive State
+
+```svelte
+<script>
+  let count = $state(0);           // Reactive state
+  let doubled = $derived(count * 2); // Computed value
+</script>
+```
+
+### Component Props
+
+```svelte
+<script>
+  let { name, count = 0 } = $props();
+  let { value = $bindable() } = $props(); // Two-way binding
+</script>
+```
+
+### Snippets (replacing slots)
+
+```svelte
+<script>
+  let { children, header } = $props();
+</script>
+
+{@render header?.()}
+{@render children()}
+```
+
+### Event Handlers
+
+```svelte
+<!-- Svelte 5: use onclick, not on:click -->
+<button onclick={() => count++}>Click</button>
+```
+
+### Callback Props (replacing createEventDispatcher)
+
+```svelte
+<script>
+  let { onclick } = $props();
+</script>
+
+<button onclick={() => onclick?.({ data })}>Click</button>
+```
+
+## Common Mistakes
+
+1. **Using `let` without `$state`** - Variables are not reactive without `$state()`
+2. **Using `$effect` for derived values** - Use `$derived` instead
+3. **Using `on:click` syntax** - Use `onclick` in Svelte 5
+4. **Using `createEventDispatcher`** - Use callback props instead
+5. **Using `<slot>`** - Use snippets with `{@render}`
+6. **Forgetting `$bindable()`** - Required for `bind:` to work
+7. **Setting module-level state in SSR** - Causes cross-request leaks
+8. **Sequential awaits in load functions** - Use `Promise.all` for parallel requests

.agents/skills/svelte5-best-practices/references/events.md

@@ -0,0 +1,353 @@
+# Svelte 5 Events Reference
+
+## Table of Contents
+- [Event Handler Syntax](#event-handler-syntax)
+- [Callback Props Pattern](#callback-props-pattern)
+- [Context API](#context-api)
+
+---
+
+## Event Handler Syntax
+
+Svelte 5 replaces `on:click` directive syntax with standard HTML attribute syntax `onclick`.
+
+### Basic Event Handlers
+
+**Svelte 4:**
+```svelte
+<button on:click={handleClick}>Click</button>
+<input on:input={handleInput} />
+<form on:submit={handleSubmit}>...</form>
+```
+
+**Svelte 5:**
+```svelte
+<button onclick={handleClick}>Click</button>
+<input oninput={handleInput} />
+<form onsubmit={handleSubmit}>...</form>
+```
+
+### Event Modifiers Migration
+
+Event modifiers no longer exist. Use wrapper functions:
+
+**Svelte 4:**
+```svelte
+<form on:submit|preventDefault={handleSubmit}>...</form>
+<button on:click|stopPropagation={handleClick}>...</button>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  function handleSubmit(event) {
+    event.preventDefault();
+    // ... handle form
+  }
+
+  function handleClick(event) {
+    event.stopPropagation();
+    // ... handle click
+  }
+</script>
+
+<form onsubmit={handleSubmit}>...</form>
+<button onclick={handleClick}>...</button>
+```
+
+### Capture, Passive, and NonPassive
+
+```svelte
+<!-- Capture phase -->
+<div onclickcapture={handleCapture}>
+  <button onclick={handleClick}>Click</button>
+</div>
+
+<!-- Passive listener -->
+<div ontouchstartpassive={handleTouch}>...</div>
+
+<!-- Non-passive -->
+<div ontouchmovenonpassive={(e) => e.preventDefault()}>...</div>
+```
+
+### Inline Handlers
+
+```svelte
+<button onclick={() => count++}>Count: {count}</button>
+<input oninput={(e) => name = e.target.value} />
+```
+
+### Event Handler Shorthand
+
+```svelte
+<script>
+  function onclick(event) {
+    console.log('Clicked!', event);
+  }
+</script>
+
+<button {onclick}>Click</button>
+```
+
+### Spreading Event Handlers
+
+```svelte
+<script>
+  let handlers = {
+    onclick: () => console.log('clicked'),
+    onmouseenter: () => console.log('entered'),
+    onmouseleave: () => console.log('left')
+  };
+</script>
+
+<button {...handlers}>Hover or Click</button>
+```
+
+### Multiple Handlers for Same Event
+
+In Svelte 5, combine logic into one handler:
+
+```svelte
+<script>
+  function handleClick(event) {
+    handler1(event);
+    handler2(event);
+  }
+</script>
+
+<button onclick={handleClick}>...</button>
+```
+
+### TypeScript Event Typing
+
+```svelte
+<script lang="ts">
+  function handleClick(event: MouseEvent) {
+    console.log(event.clientX, event.clientY);
+  }
+
+  function handleInput(event: Event) {
+    const target = event.target as HTMLInputElement;
+    console.log(target.value);
+  }
+
+  function handleSubmit(event: SubmitEvent) {
+    event.preventDefault();
+    const formData = new FormData(event.currentTarget as HTMLFormElement);
+  }
+</script>
+```
+
+---
+
+## Callback Props Pattern
+
+Svelte 5 deprecates `createEventDispatcher` in favor of callback props for component-to-parent communication.
+
+### Basic Event Pattern
+
+**Svelte 4:**
+```svelte
+<!-- Button.svelte -->
+<script>
+  import { createEventDispatcher } from 'svelte';
+  const dispatch = createEventDispatcher();
+</script>
+
+<button on:click={() => dispatch('click', { timestamp: Date.now() })}>Click</button>
+
+<!-- Parent.svelte -->
+<Button on:click={(e) => console.log(e.detail)} />
+```
+
+**Svelte 5:**
+```svelte
+<!-- Button.svelte -->
+<script>
+  let { onclick } = $props();
+</script>
+
+<button onclick={() => onclick?.({ timestamp: Date.now() })}>Click</button>
+
+<!-- Parent.svelte -->
+<Button onclick={(data) => console.log(data)} />
+```
+
+### Multiple Callbacks
+
+```svelte
+<!-- Dialog.svelte -->
+<script>
+  let { onconfirm, oncancel, onclose } = $props();
+</script>
+
+<dialog>
+  <button onclick={() => onconfirm?.()}>Confirm</button>
+  <button onclick={() => oncancel?.()}>Cancel</button>
+  <button onclick={() => onclose?.()}>X</button>
+</dialog>
+
+<!-- Parent.svelte -->
+<Dialog
+  onconfirm={() => save()}
+  oncancel={() => reset()}
+  onclose={() => visible = false}
+/>
+```
+
+### Typed Callbacks with TypeScript
+
+```svelte
+<script lang="ts">
+  interface Props {
+    value?: string;
+    onsearch?: (query: string) => void;
+    onchange?: (value: string) => void;
+    onclear?: () => void;
+  }
+
+  let { value = '', onsearch, onchange, onclear }: Props = $props();
+
+  function handleInput(e: Event) {
+    const newValue = (e.target as HTMLInputElement).value;
+    value = newValue;
+    onchange?.(newValue);
+  }
+</script>
+```
+
+### Forwarding Native Events
+
+```svelte
+<script lang="ts">
+  import type { MouseEventHandler } from 'svelte/elements';
+
+  interface Props {
+    onclick?: MouseEventHandler<HTMLButtonElement>;
+    children: import('svelte').Snippet;
+  }
+
+  let { onclick, children, ...rest }: Props = $props();
+</script>
+
+<button {onclick} {...rest}>{@render children()}</button>
+```
+
+---
+
+## Context API
+
+Context functions must be called synchronously during component initialization.
+
+### Correct Context Usage
+
+```svelte
+<script>
+  import { setContext, getContext } from 'svelte';
+
+  // These run during initialization - CORRECT
+  setContext('theme', 'dark');
+  const theme = getContext('theme');
+
+  // INCORRECT - in $effect or callback
+  // $effect(() => { setContext('theme', 'dark'); }); // ERROR
+</script>
+```
+
+### Reactive Context Values
+
+Pass `$state` objects for reactive context:
+
+```svelte
+<!-- Provider.svelte -->
+<script>
+  import { setContext } from 'svelte';
+
+  let theme = $state('light');
+
+  setContext('theme', {
+    get current() { return theme; },
+    toggle() { theme = theme === 'light' ? 'dark' : 'light'; }
+  });
+
+  let { children } = $props();
+</script>
+
+{@render children()}
+
+<!-- Consumer.svelte -->
+<script>
+  import { getContext } from 'svelte';
+  const themeContext = getContext('theme');
+</script>
+
+<p>Theme: {themeContext.current}</p>
+<button onclick={themeContext.toggle}>Toggle</button>
+```
+
+### Type-Safe Context Pattern
+
+```ts
+// context.ts
+import { setContext, getContext } from 'svelte';
+
+const THEME_KEY = Symbol('theme');
+
+interface ThemeContext {
+  current: 'light' | 'dark';
+  toggle: () => void;
+}
+
+export function setThemeContext(context: ThemeContext) {
+  setContext(THEME_KEY, context);
+}
+
+export function getThemeContext(): ThemeContext {
+  const context = getContext<ThemeContext>(THEME_KEY);
+  if (!context) throw new Error('Theme context not found');
+  return context;
+}
+```
+
+### Avoid Generic Keys
+
+```svelte
+<script>
+  // Option 1: Symbol
+  const USER_KEY = Symbol('user');
+  setContext(USER_KEY, userData);
+
+  // Option 2: Unique string
+  setContext('myapp:user', userData);
+
+  // Option 3: Object key
+  const userKey = {};
+  setContext(userKey, userData);
+</script>
+```
+
+### hasContext Check
+
+```svelte
+<script>
+  import { hasContext, getContext } from 'svelte';
+
+  const hasTheme = hasContext('theme');
+  const theme = hasTheme ? getContext('theme') : { current: 'light' };
+</script>
+```
+
+### Context Boundaries
+
+Context flows down the component tree:
+
+```svelte
+<!-- Parent.svelte -->
+<script>
+  import { getContext, setContext } from 'svelte';
+  const level = getContext('level'); // 0
+  setContext('level', level + 1); // Override for children
+</script>
+
+<Child /> <!-- Will see level = 1 -->
+```

.agents/skills/svelte5-best-practices/references/migration.md

@@ -0,0 +1,339 @@
+# Svelte 4 to Svelte 5 Migration Reference
+
+## Table of Contents
+- [Migrating Reactive Statements](#migrating-reactive-statements)
+- [Migrating Stores to Runes](#migrating-stores-to-runes)
+
+---
+
+## Migrating Reactive Statements
+
+Svelte 5 replaces `$:` with `$derived` (for values) and `$effect` (for side effects).
+
+### Computed Values: $: to $derived
+
+**Svelte 4:**
+```svelte
+<script>
+  let count = 0;
+  $: doubled = count * 2;
+  $: quadrupled = doubled * 2;
+</script>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let count = $state(0);
+  let doubled = $derived(count * 2);
+  let quadrupled = $derived(doubled * 2);
+</script>
+```
+
+### Complex Computed Values: $derived.by
+
+**Svelte 4:**
+```svelte
+<script>
+  let items = [];
+  let filter = 'all';
+
+  $: filteredItems = {
+    if (filter === 'all') return items;
+    if (filter === 'active') return items.filter(i => !i.done);
+    return items.filter(i => i.done);
+  };
+</script>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let items = $state([]);
+  let filter = $state('all');
+
+  let filteredItems = $derived.by(() => {
+    if (filter === 'all') return items;
+    if (filter === 'active') return items.filter(i => !i.done);
+    return items.filter(i => i.done);
+  });
+</script>
+```
+
+### Side Effects: $: to $effect
+
+**Svelte 4:**
+```svelte
+<script>
+  let count = 0;
+  $: console.log('Count changed:', count);
+  $: document.title = `Count: ${count}`;
+</script>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let count = $state(0);
+
+  $effect(() => { console.log('Count changed:', count); });
+  $effect(() => { document.title = `Count: ${count}`; });
+</script>
+```
+
+### Conditional Side Effects
+
+**Svelte 4:**
+```svelte
+<script>
+  let value;
+  $: if (value > 100) { alert('Value too high!'); }
+</script>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let value = $state(0);
+
+  $effect(() => {
+    if (value > 100) { alert('Value too high!'); }
+  });
+</script>
+```
+
+### Props Migration
+
+**Svelte 4:**
+```svelte
+<script>
+  export let name;
+  export let count = 0;
+  $: greeting = `Hello, ${name}!`;
+</script>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let { name, count = 0 } = $props();
+  let greeting = $derived(`Hello, ${name}!`);
+</script>
+```
+
+### Effect with Cleanup
+
+**Svelte 4:**
+```svelte
+<script>
+  import { onDestroy } from 'svelte';
+
+  let count = 0;
+  let interval;
+
+  $: {
+    clearInterval(interval);
+    interval = setInterval(() => console.log(count), 1000);
+  }
+
+  onDestroy(() => clearInterval(interval));
+</script>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let count = $state(0);
+
+  $effect(() => {
+    const interval = setInterval(() => console.log(count), 1000);
+    return () => clearInterval(interval); // Cleanup built-in
+  });
+</script>
+```
+
+### Migration Cheat Sheet
+
+| Svelte 4 Pattern | Svelte 5 Replacement |
+|------------------|----------------------|
+| `let x = 0` (in component) | `let x = $state(0)` |
+| `export let prop` | `let { prop } = $props()` |
+| `$: derived = expr` | `let derived = $derived(expr)` |
+| `$: { complex }` (value) | `let x = $derived.by(() => { ... })` |
+| `$: console.log(x)` | `$effect(() => console.log(x))` |
+| `$: if (x) { ... }` | `$effect(() => { if (x) { ... } })` |
+| `$: document.title = x` | `$effect(() => { document.title = x })` |
+
+### Automated Migration
+
+```bash
+npx sv migrate svelte-5
+```
+
+---
+
+## Migrating Stores to Runes
+
+Svelte 5 runes can replace most store use cases with simpler, more direct reactive state.
+
+### Local Component State
+
+**Svelte 4:**
+```svelte
+<script>
+  import { writable } from 'svelte/store';
+
+  const count = writable(0);
+  function increment() { count.update(n => n + 1); }
+</script>
+
+<button on:click={increment}>Count: {$count}</button>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let count = $state(0);
+  function increment() { count++; }
+</script>
+
+<button onclick={increment}>Count: {count}</button>
+```
+
+### Shared State Across Components
+
+**Svelte 4 (stores.ts):**
+```ts
+import { writable } from 'svelte/store';
+export const user = writable(null);
+export const theme = writable('light');
+```
+
+**Svelte 5 (state.svelte.ts):**
+```ts
+export const user = $state<User | null>(null);
+export const theme = $state({ current: 'light' as 'light' | 'dark' });
+
+export function setTheme(newTheme: 'light' | 'dark') {
+  theme.current = newTheme;
+}
+```
+
+```svelte
+<script>
+  import { theme, setTheme } from './state.svelte';
+</script>
+
+<p>Theme: {theme.current}</p>
+<button onclick={() => setTheme('dark')}>Dark Mode</button>
+```
+
+### Derived Store to $derived
+
+**Svelte 4:**
+```ts
+import { writable, derived } from 'svelte/store';
+export const items = writable([]);
+export const completedCount = derived(items, $items =>
+  $items.filter(i => i.done).length
+);
+```
+
+**Svelte 5:**
+```ts
+// state.svelte.ts
+export const items = $state<Item[]>([]);
+
+export function getCompletedCount() {
+  return items.filter(i => i.done).length;
+}
+```
+
+```svelte
+<script>
+  import { items } from './state.svelte';
+  let completedCount = $derived(items.filter(i => i.done).length);
+</script>
+```
+
+### Custom Store to Reactive Class
+
+**Svelte 4:**
+```ts
+function createCounter() {
+  const { subscribe, set, update } = writable(0);
+  return {
+    subscribe,
+    increment: () => update(n => n + 1),
+    decrement: () => update(n => n - 1),
+    reset: () => set(0)
+  };
+}
+export const counter = createCounter();
+```
+
+**Svelte 5:**
+```ts
+// counter.svelte.ts
+class Counter {
+  value = $state(0);
+  increment() { this.value++; }
+  decrement() { this.value--; }
+  reset() { this.value = 0; }
+}
+
+export const counter = new Counter();
+```
+
+```svelte
+<script>
+  import { counter } from './counter.svelte';
+</script>
+
+<p>{counter.value}</p>
+<button onclick={() => counter.increment()}>+</button>
+```
+
+### Async State Pattern
+
+**Svelte 5:**
+```ts
+// api.svelte.ts
+export const state = $state({
+  data: null as Data | null,
+  loading: false,
+  error: null as Error | null
+});
+
+export async function fetchData() {
+  state.loading = true;
+  state.error = null;
+
+  try {
+    const res = await fetch('/api/data');
+    state.data = await res.json();
+  } catch (e) {
+    state.error = e as Error;
+  } finally {
+    state.loading = false;
+  }
+}
+```
+
+### When to Still Use Stores
+
+1. **Library interop** - Libraries that expect Svelte stores
+2. **Legacy code** - Gradual migration
+3. **Observable patterns** - When you need the subscribe API
+4. **Server-side rendering** - Stores have built-in SSR handling
+
+### Store to Rune Cheat Sheet
+
+| Store Pattern | Rune Replacement |
+|---------------|------------------|
+| `writable(value)` | `$state(value)` |
+| `$store` (auto-subscribe) | Direct access to `$state` value |
+| `store.set(x)` | `state = x` |
+| `store.update(fn)` | Direct mutation or reassignment |
+| `derived(store, fn)` | `$derived(fn())` in component |
+| `readable(value, start)` | `$state` + `$effect` for setup |

.agents/skills/svelte5-best-practices/references/performance.md

@@ -0,0 +1,443 @@
+# Svelte 5 Performance Reference
+
+## Table of Contents
+- [Universal Reactivity](#universal-reactivity)
+- [Avoiding Over-Reactivity](#avoiding-over-reactivity)
+- [Preventing Load Waterfalls](#preventing-load-waterfalls)
+- [Streaming Non-Critical Data](#streaming-non-critical-data)
+- [Component Testing](#component-testing)
+
+---
+
+## Universal Reactivity
+
+Svelte 5 allows runes in `.svelte.js` or `.svelte.ts` files for shared state outside components.
+
+### Shared Counter State
+
+```ts
+// counter.svelte.ts
+export const counter = $state({ count: 0 });
+
+export function increment() { counter.count++; }
+export function decrement() { counter.count--; }
+export function reset() { counter.count = 0; }
+```
+
+```svelte
+<script>
+  import { counter, increment } from './counter.svelte';
+</script>
+
+<p>Count: {counter.count}</p>
+<button onclick={increment}>+</button>
+```
+
+### Object State with Getters
+
+```ts
+// user.svelte.ts
+const state = $state<User>({ firstName: '', lastName: '', email: '' });
+
+export const user = {
+  get firstName() { return state.firstName; },
+  set firstName(v: string) { state.firstName = v; },
+  get fullName() { return `${state.firstName} ${state.lastName}`; },
+  get isValid() { return state.firstName && state.email.includes('@'); }
+};
+```
+
+### Reactive Class Pattern
+
+```ts
+// todo.svelte.ts
+class TodoStore {
+  items = $state<Todo[]>([]);
+  filter = $state<'all' | 'active' | 'completed'>('all');
+
+  get filtered() {
+    switch (this.filter) {
+      case 'active': return this.items.filter(t => !t.done);
+      case 'completed': return this.items.filter(t => t.done);
+      default: return this.items;
+    }
+  }
+
+  add(text: string) {
+    this.items.push({ id: Date.now(), text, done: false });
+  }
+}
+
+export const todos = new TodoStore();
+```
+
+### Important Notes
+
+1. **File extension matters**: Must use `.svelte.js` or `.svelte.ts`
+2. **No $derived in module scope**: Use getters for derived values
+3. **SSR caution**: Avoid initializing browser-only state at module level
+
+---
+
+## Avoiding Over-Reactivity
+
+Common mistakes with runes can cause unnecessary re-renders, infinite loops, or degraded performance.
+
+### Anti-Pattern 1: Using $effect to Set Derived Values
+
+**WRONG:**
+```svelte
+<script>
+  let count = $state(0);
+  let doubled = $state(0);
+  $effect(() => { doubled = count * 2; }); // Anti-pattern!
+</script>
+```
+
+**CORRECT:**
+```svelte
+<script>
+  let count = $state(0);
+  let doubled = $derived(count * 2);
+</script>
+```
+
+### Anti-Pattern 2: Circular Dependencies
+
+**WRONG:**
+```svelte
+<script>
+  let a = $state(1);
+  let b = $state(2);
+
+  $effect(() => {
+    if (a > 10) b = 0;
+    if (b > 10) a = 0; // Triggers the effect again!
+  });
+</script>
+```
+
+**CORRECT: Use separate effects or event handlers**
+
+### Anti-Pattern 3: Not Using untrack
+
+**WRONG:**
+```svelte
+<script>
+  let count = $state(0);
+  let log = $state([]);
+
+  $effect(() => {
+    log.push(`Count is ${count}`); // log change triggers re-run!
+  });
+</script>
+```
+
+**CORRECT:**
+```svelte
+<script>
+  import { untrack } from 'svelte';
+
+  let count = $state(0);
+  let log = $state([]);
+
+  $effect(() => {
+    untrack(() => { log.push(`Count is ${count}`); });
+  });
+</script>
+```
+
+### Anti-Pattern 4: Heavy Computations in $derived
+
+**WRONG:**
+```svelte
+<script>
+  let items = $state([/* thousands */]);
+  let filter = $state('');
+
+  let filtered = $derived(
+    items.filter(item => JSON.stringify(item).includes(filter))
+  );
+</script>
+```
+
+**CORRECT: Debounce expensive computations**
+```svelte
+<script>
+  let filter = $state('');
+  let debouncedFilter = $state('');
+
+  $effect(() => {
+    const timeout = setTimeout(() => { debouncedFilter = filter; }, 300);
+    return () => clearTimeout(timeout);
+  });
+
+  let filtered = $derived(
+    items.filter(item => item.name.includes(debouncedFilter))
+  );
+</script>
+```
+
+### Anti-Pattern 5: Effect for DOM Manipulation
+
+**WRONG:**
+```svelte
+<script>
+  let visible = $state(false);
+  let element;
+
+  $effect(() => {
+    if (element) element.style.display = visible ? 'block' : 'none';
+  });
+</script>
+```
+
+**CORRECT:**
+```svelte
+{#if visible}<div>Content</div>{/if}
+<!-- Or -->
+<div class:hidden={!visible}>Content</div>
+```
+
+### Performance Tips
+
+1. Use `$derived` over `$effect` for computed values
+2. Debounce expensive reactive computations
+3. Use `untrack` to prevent unnecessary dependencies
+4. Group related state into objects
+5. Let Svelte handle DOM updates
+
+---
+
+## Preventing Load Waterfalls
+
+Sequential API calls multiply latency. Use parallel requests and streaming.
+
+### Anti-Pattern: Waterfall
+
+**WRONG (3 seconds total):**
+```ts
+export const load = async ({ fetch }) => {
+  const user = await fetch('/api/user').then(r => r.json());     // 1s
+  const posts = await fetch(`/api/users/${user.id}/posts`).then(r => r.json()); // 1s
+  const comments = await fetch('/api/comments').then(r => r.json()); // 1s
+  return { user, posts, comments };
+};
+```
+
+### Pattern 1: Parallel with Promise.all
+
+**CORRECT (1 second total):**
+```ts
+export const load = async ({ fetch }) => {
+  const [user, posts, comments] = await Promise.all([
+    fetch('/api/user').then(r => r.json()),
+    fetch('/api/posts').then(r => r.json()),
+    fetch('/api/comments').then(r => r.json())
+  ]);
+  return { user, posts, comments };
+};
+```
+
+### Pattern 2: Partial Dependencies
+
+```ts
+export const load = async ({ fetch }) => {
+  const user = await fetch('/api/user').then(r => r.json());
+
+  const [posts, followers] = await Promise.all([
+    fetch(`/api/users/${user.id}/posts`).then(r => r.json()),
+    fetch(`/api/users/${user.id}/followers`).then(r => r.json())
+  ]);
+
+  return { user, posts, followers };
+};
+```
+
+### Pattern 3: Streaming Non-Critical Data
+
+```ts
+export const load = async ({ fetch }) => {
+  const user = await fetch('/api/user').then(r => r.json());
+
+  return {
+    user,
+    recommendations: fetch('/api/recommendations').then(r => r.json()),
+    analytics: fetch('/api/analytics').then(r => r.json())
+  };
+};
+```
+
+### Performance Comparison
+
+| Pattern | 3 APIs x 1s each |
+|---------|------------------|
+| Sequential | 3 seconds |
+| Parallel (Promise.all) | 1 second |
+| Streaming | 0s initial, streams rest |
+
+---
+
+## Streaming Non-Critical Data
+
+Return promises from load functions to stream non-essential data after initial page render.
+
+### Basic Streaming
+
+**WRONG (blocks on slow data):**
+```ts
+export const load = async ({ fetch }) => {
+  const user = await fetch('/api/user').then(r => r.json());     // 100ms
+  const analytics = await fetch('/api/analytics').then(r => r.json()); // 2000ms
+  return { user, analytics }; // Page blocked for 2.1 seconds
+};
+```
+
+**CORRECT (stream slow data):**
+```ts
+export const load = async ({ fetch }) => {
+  const user = await fetch('/api/user').then(r => r.json());
+  const analytics = fetch('/api/analytics').then(r => r.json()); // Don't await
+
+  return {
+    user,      // Available in 100ms
+    analytics  // Streams when ready
+  };
+};
+```
+
+### Component Handling
+
+```svelte
+<script lang="ts">
+  import type { PageProps } from './$types';
+  let { data }: PageProps = $props();
+</script>
+
+<header><h1>Welcome, {data.user.name}</h1></header>
+
+<aside>
+  {#await data.analytics}
+    <div class="skeleton">Loading analytics...</div>
+  {:then analytics}
+    <div class="analytics">
+      <p>Page views: {analytics.views}</p>
+    </div>
+  {:catch}
+    <div class="error">Failed to load analytics</div>
+  {/await}
+</aside>
+```
+
+### When to Stream
+
+| Data Type | Stream? | Reason |
+|-----------|---------|--------|
+| User info | No | Critical for layout |
+| Main content | No | Users came for this |
+| Analytics | Yes | Not user-facing |
+| Recommendations | Yes | Supplementary |
+| Comments | Maybe | Important but can load later |
+
+---
+
+## Component Testing
+
+Svelte 5 components with runes require proper Vitest configuration.
+
+### Option 1: Vitest Browser Mode (Recommended)
+
+```ts
+// vitest.config.ts
+import { defineConfig } from 'vitest/config';
+import { svelte } from '@sveltejs/vite-plugin-svelte';
+
+export default defineConfig({
+  plugins: [svelte()],
+  test: {
+    browser: {
+      enabled: true,
+      provider: 'playwright',
+      name: 'chromium'
+    }
+  }
+});
+```
+
+### Option 2: JSDOM with @testing-library/svelte
+
+```ts
+// vitest.config.ts
+import { defineConfig } from 'vitest/config';
+import { svelte } from '@sveltejs/vite-plugin-svelte';
+
+export default defineConfig({
+  plugins: [svelte({ hot: !process.env.VITEST })],
+  test: {
+    environment: 'jsdom',
+    include: ['src/**/*.{test,spec}.{js,ts}'],
+    globals: true
+  }
+});
+```
+
+### Basic Component Test
+
+```ts
+import { render, screen, fireEvent } from '@testing-library/svelte';
+import { expect, test } from 'vitest';
+import Counter from './Counter.svelte';
+
+test('increments count when clicked', async () => {
+  render(Counter);
+
+  const button = screen.getByRole('button');
+  expect(button).toHaveTextContent('Count: 0');
+
+  await fireEvent.click(button);
+  expect(button).toHaveTextContent('Count: 1');
+});
+```
+
+### Testing Props
+
+```ts
+test('renders with custom name', () => {
+  render(Greeting, { props: { name: 'Alice' } });
+  expect(screen.getByText('Hello, Alice!')).toBeInTheDocument();
+});
+```
+
+### Testing Callbacks
+
+```ts
+import { vi } from 'vitest';
+
+test('calls onclick callback when clicked', async () => {
+  const handleClick = vi.fn();
+  render(Button, { props: { onclick: handleClick } });
+
+  await fireEvent.click(screen.getByRole('button'));
+  expect(handleClick).toHaveBeenCalledTimes(1);
+});
+```
+
+### Testing Async Components
+
+```ts
+import { waitFor } from '@testing-library/svelte';
+
+test('loads and displays user data', async () => {
+  global.fetch = vi.fn().mockResolvedValue({
+    ok: true,
+    json: () => Promise.resolve({ name: 'Alice' })
+  });
+
+  render(UserProfile, { props: { userId: '123' } });
+  expect(screen.getByText('Loading...')).toBeInTheDocument();
+
+  await waitFor(() => {
+    expect(screen.getByText('Alice')).toBeInTheDocument();
+  });
+});
+```

.agents/skills/svelte5-best-practices/references/runes.md

@@ -0,0 +1,394 @@
+# Svelte 5 Runes Reference
+
+## Table of Contents
+- [$state - Reactive State](#state---reactive-state)
+- [$derived - Computed Values](#derived---computed-values)
+- [$effect - Side Effects](#effect---side-effects)
+- [$props - Component Props](#props---component-props)
+- [$bindable - Two-Way Binding](#bindable---two-way-binding)
+- [$inspect - Debugging](#inspect---debugging)
+
+---
+
+## $state - Reactive State
+
+In Svelte 5, plain `let` declarations are no longer automatically reactive. Use `$state()` for reactive state.
+
+### Basic Usage
+
+```svelte
+<script>
+  let count = $state(0);
+</script>
+
+<button onclick={() => count++}>
+  Clicks: {count}
+</button>
+```
+
+### Object and Array State
+
+Objects and arrays are deeply reactive by default:
+
+```svelte
+<script>
+  let user = $state({ name: 'Alice', age: 30 });
+  let items = $state(['apple', 'banana']);
+</script>
+
+<button onclick={() => user.age++}>Age: {user.age}</button>
+<button onclick={() => items.push('cherry')}>Items: {items.length}</button>
+```
+
+### Class State
+
+```svelte
+<script>
+  class Counter {
+    count = $state(0);
+    increment() { this.count++; }
+  }
+  const counter = new Counter();
+</script>
+
+<button onclick={() => counter.increment()}>{counter.count}</button>
+```
+
+### Raw State (Opt-out of Deep Reactivity)
+
+```svelte
+<script>
+  let items = $state.raw([1, 2, 3]);
+
+  // This WON'T trigger an update:
+  items.push(4);
+
+  // This WILL trigger an update:
+  items = [...items, 4];
+</script>
+```
+
+---
+
+## $derived - Computed Values
+
+Replaces `$:` reactive statements for computed values.
+
+### Basic Usage
+
+```svelte
+<script>
+  let count = $state(0);
+  let doubled = $derived(count * 2);
+  let quadrupled = $derived(doubled * 2);
+</script>
+```
+
+### Complex Derivations with $derived.by
+
+```svelte
+<script>
+  let items = $state([1, 2, 3, 4, 5]);
+  let filter = $state('even');
+
+  let filteredItems = $derived.by(() => {
+    if (filter === 'even') return items.filter(n => n % 2 === 0);
+    return items.filter(n => n % 2 !== 0);
+  });
+</script>
+```
+
+### Deriving from Props
+
+```svelte
+<script>
+  let { firstName, lastName } = $props();
+  let fullName = $derived(`${firstName} ${lastName}`);
+</script>
+```
+
+### $derived vs $effect
+
+Use `$derived` for computing values, `$effect` for side effects:
+
+```svelte
+<script>
+  let count = $state(0);
+
+  // CORRECT: Use $derived for computed values
+  let doubled = $derived(count * 2);
+
+  // INCORRECT: Don't use $effect to set derived values
+  // let doubled;
+  // $effect(() => { doubled = count * 2; }); // Anti-pattern!
+</script>
+```
+
+---
+
+## $effect - Side Effects
+
+Runs code when component mounts and when dependencies change. Requires cleanup for subscriptions.
+
+### Basic Effect with Cleanup
+
+```svelte
+<script>
+  let count = $state(0);
+
+  $effect(() => {
+    const interval = setInterval(() => count++, 1000);
+    return () => clearInterval(interval); // Cleanup
+  });
+</script>
+```
+
+### DOM Event Listeners
+
+```svelte
+<script>
+  let mouseX = $state(0);
+  let mouseY = $state(0);
+
+  $effect(() => {
+    function handleMouseMove(event) {
+      mouseX = event.clientX;
+      mouseY = event.clientY;
+    }
+    window.addEventListener('mousemove', handleMouseMove);
+    return () => window.removeEventListener('mousemove', handleMouseMove);
+  });
+</script>
+```
+
+### External Subscriptions
+
+```svelte
+<script>
+  let { userId } = $props();
+  let userData = $state(null);
+
+  $effect(() => {
+    const unsubscribe = database.subscribe(`users/${userId}`, (data) => {
+      userData = data;
+    });
+    return () => unsubscribe();
+  });
+</script>
+```
+
+### $effect.pre for Pre-DOM Updates
+
+```svelte
+<script>
+  let div;
+  let messages = $state([]);
+
+  $effect.pre(() => {
+    if (div) {
+      const shouldScroll = div.scrollTop + div.clientHeight >= div.scrollHeight - 20;
+      if (shouldScroll) {
+        tick().then(() => { div.scrollTop = div.scrollHeight; });
+      }
+    }
+  });
+</script>
+```
+
+### Untracked Dependencies
+
+```svelte
+<script>
+  import { untrack } from 'svelte';
+
+  let count = $state(0);
+  let logCount = $state(0);
+
+  $effect(() => {
+    // Only runs when count changes, not logCount
+    console.log(count, untrack(() => logCount));
+  });
+</script>
+```
+
+---
+
+## $props - Component Props
+
+Replaces `export let` for declaring component props.
+
+### Basic Usage
+
+```svelte
+<script>
+  let { name, count = 0, disabled = false } = $props();
+</script>
+```
+
+### Rest Props Pattern
+
+```svelte
+<script>
+  let { class: className, children, ...restProps } = $props();
+</script>
+
+<div class={className} {...restProps}>
+  {@render children?.()}
+</div>
+```
+
+### Renaming Reserved Words
+
+```svelte
+<script>
+  let {
+    class: className,  // 'class' is reserved
+    for: htmlFor,      // 'for' is reserved
+    ...rest
+  } = $props();
+</script>
+```
+
+### TypeScript Props
+
+```svelte
+<script lang="ts">
+  interface Props {
+    name: string;
+    count?: number;
+    onClick?: (event: MouseEvent) => void;
+  }
+
+  let { name, count = 0, onClick }: Props = $props();
+</script>
+```
+
+### Props with Children
+
+```svelte
+<script lang="ts">
+  import type { Snippet } from 'svelte';
+
+  interface Props {
+    title: string;
+    children: Snippet;
+    footer?: Snippet;
+  }
+
+  let { title, children, footer }: Props = $props();
+</script>
+
+<article>
+  <h1>{title}</h1>
+  <main>{@render children()}</main>
+  {#if footer}<footer>{@render footer()}</footer>{/if}
+</article>
+```
+
+---
+
+## $bindable - Two-Way Binding
+
+Props must be explicitly marked with `$bindable()` to support `bind:`.
+
+### Basic Usage
+
+```svelte
+<!-- Input.svelte -->
+<script>
+  let { value = $bindable() } = $props();
+</script>
+
+<input bind:value />
+
+<!-- Parent.svelte -->
+<script>
+  import Input from './Input.svelte';
+  let name = $state('');
+</script>
+
+<Input bind:value={name} />
+```
+
+### Bindable with Default Value
+
+```svelte
+<script>
+  let { value = $bindable('default') } = $props();
+</script>
+```
+
+### Multiple Bindable Props
+
+```svelte
+<script>
+  let {
+    value = $bindable(''),
+    checked = $bindable(false),
+    selected = $bindable(null)
+  } = $props();
+</script>
+```
+
+### TypeScript with Bindable
+
+```svelte
+<script lang="ts">
+  interface Props {
+    value: string;
+    disabled?: boolean;
+  }
+
+  let { value = $bindable(''), disabled = false }: Props = $props();
+</script>
+```
+
+---
+
+## $inspect - Debugging
+
+Development-only debugging that logs values when they change. Stripped in production.
+
+### Basic Usage
+
+```svelte
+<script>
+  let count = $state(0);
+  $inspect(count); // Logs every time count changes
+</script>
+```
+
+### Multiple Values
+
+```svelte
+<script>
+  let name = $state('Alice');
+  let age = $state(30);
+  $inspect(name, age);
+</script>
+```
+
+### Custom Logging with $inspect.with
+
+```svelte
+<script>
+  let user = $state({ name: 'Alice', age: 30 });
+
+  $inspect.with((type, ...values) => {
+    if (type === 'init') console.log('Initial value:', values);
+    else console.log('Updated to:', values);
+  }, user);
+</script>
+```
+
+### Debugging with Breakpoints
+
+```svelte
+<script>
+  let data = $state({ x: 0, y: 0 });
+
+  $inspect.with((type, value) => {
+    if (type === 'update' && value.x > 100) debugger;
+  }, data);
+</script>
+```

.agents/skills/svelte5-best-practices/references/snippets.md

@@ -0,0 +1,291 @@
+# Svelte 5 Snippets Reference
+
+## Table of Contents
+- [Replacing Slots with Snippets](#replacing-slots-with-snippets)
+- [Rendering with @render](#rendering-with-render)
+
+---
+
+## Replacing Slots with Snippets
+
+Svelte 5 replaces `<slot>` with snippets - a more powerful and type-safe composition primitive.
+
+### Default Content (children)
+
+**Svelte 4:**
+```svelte
+<div class="card"><slot /></div>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let { children } = $props();
+</script>
+
+<div class="card">{@render children?.()}</div>
+```
+
+### Named Slots to Named Snippets
+
+**Svelte 4:**
+```svelte
+<header><slot name="header" /></header>
+<main><slot /></main>
+<footer><slot name="footer" /></footer>
+
+<!-- Usage -->
+<Layout>
+  <h1 slot="header">Title</h1>
+  <p>Content</p>
+  <span slot="footer">Footer</span>
+</Layout>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let { header, children, footer } = $props();
+</script>
+
+<header>{@render header?.()}</header>
+<main>{@render children?.()}</main>
+<footer>{@render footer?.()}</footer>
+
+<!-- Usage -->
+<Layout>
+  {#snippet header()}<h1>Title</h1>{/snippet}
+  <p>Content</p>
+  {#snippet footer()}<span>Footer</span>{/snippet}
+</Layout>
+```
+
+### Slot Props to Snippet Parameters
+
+**Svelte 4:**
+```svelte
+<ul>
+  {#each items as item}
+    <li><slot {item} /></li>
+  {/each}
+</ul>
+
+<List {items} let:item>
+  <span>{item.name}</span>
+</List>
+```
+
+**Svelte 5:**
+```svelte
+<script>
+  let { items, children } = $props();
+</script>
+
+<ul>
+  {#each items as item}
+    <li>{@render children?.(item)}</li>
+  {/each}
+</ul>
+
+<List {items}>
+  {#snippet children(item)}
+    <span>{item.name}</span>
+  {/snippet}
+</List>
+```
+
+### Slot Fallback to Snippet Fallback
+
+```svelte
+<script>
+  let { children } = $props();
+</script>
+
+{#if children}
+  {@render children()}
+{:else}
+  <p>Default content</p>
+{/if}
+```
+
+### Defining Snippets Within Components
+
+```svelte
+<script>
+  let items = $state([
+    { id: 1, name: 'Item 1', type: 'normal' },
+    { id: 2, name: 'Item 2', type: 'featured' }
+  ]);
+</script>
+
+{#snippet normalItem(item)}
+  <li>{item.name}</li>
+{/snippet}
+
+{#snippet featuredItem(item)}
+  <li class="featured">*** {item.name} ***</li>
+{/snippet}
+
+<ul>
+  {#each items as item}
+    {#if item.type === 'featured'}
+      {@render featuredItem(item)}
+    {:else}
+      {@render normalItem(item)}
+    {/if}
+  {/each}
+</ul>
+```
+
+### TypeScript Typing
+
+```svelte
+<script lang="ts">
+  import type { Snippet } from 'svelte';
+
+  interface Item { id: number; name: string; }
+
+  interface Props {
+    header?: Snippet;
+    children: Snippet<[item: Item]>;
+    footer?: Snippet;
+  }
+
+  let { header, children, footer }: Props = $props();
+</script>
+```
+
+---
+
+## Rendering with @render
+
+Snippets must be rendered using `{@render}`. Optional snippets need null-safe calling.
+
+### Basic Snippet Rendering
+
+```svelte
+<script>
+  let { children } = $props();
+</script>
+
+<div>{@render children()}</div>
+```
+
+### Optional Snippets
+
+Always use optional chaining for snippets that might not be provided:
+
+```svelte
+<script>
+  let { children } = $props();
+</script>
+
+{@render children?.()}
+```
+
+### Conditional Rendering
+
+```svelte
+<script>
+  let { header, children, footer } = $props();
+</script>
+
+{#if header}
+  <header>{@render header()}</header>
+{/if}
+
+<main>{@render children?.()}</main>
+
+{#if footer}
+  <footer>{@render footer()}</footer>
+{/if}
+```
+
+### Rendering with Arguments
+
+```svelte
+<script>
+  let { items, itemTemplate } = $props();
+</script>
+
+<ul>
+  {#each items as item, index}
+    <li>{@render itemTemplate(item, index)}</li>
+  {/each}
+</ul>
+
+<!-- Usage -->
+<List {items}>
+  {#snippet itemTemplate(item, index)}
+    <span>{index + 1}. {item.name}</span>
+  {/snippet}
+</List>
+```
+
+### Rendering Multiple Times
+
+Snippets can be rendered multiple times:
+
+```svelte
+<script>
+  let { icon } = $props();
+</script>
+
+<button>
+  {@render icon?.()}
+  <span>Click me</span>
+  {@render icon?.()}
+</button>
+```
+
+### Rendering Dynamic Snippets
+
+```svelte
+<script>
+  let { normalView, editView, isEditing } = $props();
+  let currentView = $derived(isEditing ? editView : normalView);
+</script>
+
+{@render currentView?.()}
+```
+
+### TypeScript with @render
+
+```svelte
+<script lang="ts">
+  import type { Snippet } from 'svelte';
+
+  interface Props {
+    children: Snippet;
+    header?: Snippet;
+    row: Snippet<[data: { id: number; name: string }]>;
+  }
+
+  let { children, header, row }: Props = $props();
+</script>
+
+{@render header?.()}
+{@render children()}
+{@render row({ id: 1, name: 'Test' })}
+```
+
+### Passing Snippets to Child Components
+
+```svelte
+<!-- Wrapper.svelte -->
+<script>
+  import Inner from './Inner.svelte';
+  let { itemRenderer } = $props();
+</script>
+
+<Inner {itemRenderer} />
+
+<!-- Inner.svelte -->
+<script>
+  let { itemRenderer } = $props();
+</script>
+
+{#each items as item}
+  {@render itemRenderer?.(item)}
+{/each}
+```

.agents/skills/svelte5-best-practices/references/sveltekit.md

@@ -0,0 +1,401 @@
+# SvelteKit Patterns Reference
+
+## Table of Contents
+- [Load Function Types](#load-function-types)
+- [Page Props Typing](#page-props-typing)
+- [Form Actions Error Handling](#form-actions-error-handling)
+- [SSR State Isolation](#ssr-state-isolation)
+
+---
+
+## Load Function Types
+
+SvelteKit has two load function types: universal (`+page.js`) and server-only (`+page.server.ts`).
+
+### When to Use Each
+
+| Use +page.server.ts | Use +page.js |
+|---------------------|--------------|
+| Accessing secrets/credentials | Public APIs only |
+| Database connections | Non-serializable data (functions, classes) |
+| Server-only APIs | Client-side caching benefits |
+| Sensitive business logic | |
+
+### Security: Secrets in Server Load
+
+**WRONG (secrets exposed):**
+```ts
+// +page.js - DANGEROUS: runs in browser!
+export const load = async ({ fetch }) => {
+  const response = await fetch('https://api.stripe.com/charges', {
+    headers: { 'Authorization': `Bearer ${STRIPE_SECRET_KEY}` } // EXPOSED!
+  });
+  return { charges: await response.json() };
+};
+```
+
+**CORRECT:**
+```ts
+// +page.server.ts - only runs on server
+import { STRIPE_SECRET_KEY } from '$env/static/private';
+
+export const load = async ({ fetch }) => {
+  const response = await fetch('https://api.stripe.com/charges', {
+    headers: { 'Authorization': `Bearer ${STRIPE_SECRET_KEY}` }
+  });
+  return { charges: await response.json() };
+};
+```
+
+### Serialization: Non-serializable in Universal Load
+
+**WRONG (server load can't serialize functions):**
+```ts
+// +page.server.ts
+export const load = async () => {
+  return {
+    formatDate: (date: Date) => date.toLocaleDateString(), // ERROR
+    parser: new DOMParser() // ERROR
+  };
+};
+```
+
+**CORRECT:**
+```ts
+// +page.js
+export const load = async () => {
+  return {
+    formatDate: (date: Date) => date.toLocaleDateString(), // OK
+    parser: typeof window !== 'undefined' ? new DOMParser() : null
+  };
+};
+```
+
+### Database Access
+
+```ts
+// +page.server.ts - CORRECT
+import { db } from '$lib/server/database';
+
+export const load = async () => {
+  const users = await db.query('SELECT * FROM users');
+  return { users };
+};
+```
+
+### Environment Variables
+
+```ts
+// +page.server.ts - Private env vars
+import { DATABASE_URL, API_SECRET } from '$env/static/private';
+
+// +page.js - Only public env vars
+import { PUBLIC_API_URL } from '$env/static/public';
+```
+
+---
+
+## Page Props Typing
+
+SvelteKit generates types in `./$types` for full type safety with `$props()`.
+
+### Basic Page Data Typing
+
+```svelte
+<!-- +page.svelte -->
+<script lang="ts">
+  import type { PageProps } from './$types';
+
+  let { data }: PageProps = $props();
+</script>
+
+<h1>{data.title}</h1>
+```
+
+### Page Data with Form Actions
+
+```svelte
+<script lang="ts">
+  import type { PageProps } from './$types';
+
+  let { data, form }: PageProps = $props();
+</script>
+
+{#if form?.success}
+  <p class="success">{form.message}</p>
+{/if}
+
+{#if form?.error}
+  <p class="error">{form.error}</p>
+{/if}
+```
+
+### Layout Data Typing
+
+```svelte
+<!-- +layout.svelte -->
+<script lang="ts">
+  import type { LayoutProps } from './$types';
+
+  let { data, children }: LayoutProps = $props();
+</script>
+
+<nav>
+  {#if data.user}<span>Welcome, {data.user.name}</span>{/if}
+</nav>
+
+{@render children()}
+```
+
+### Corresponding Load Function
+
+```ts
+// +page.server.ts
+import type { PageServerLoad, Actions } from './$types';
+
+export const load: PageServerLoad = async () => {
+  return {
+    title: 'My Page',
+    items: await fetchItems()
+  };
+};
+
+export const actions: Actions = {
+  default: async ({ request }) => {
+    return { success: true, message: 'Saved successfully' };
+  }
+};
+```
+
+### Error Page
+
+```svelte
+<!-- +error.svelte -->
+<script lang="ts">
+  import { page } from '$app/state';
+</script>
+
+<h1>{page.status}: {page.error?.message}</h1>
+```
+
+---
+
+## Form Actions Error Handling
+
+SvelteKit distinguishes between validation errors (`fail()`) and unexpected errors (`throw error()`).
+
+### Use fail() for Validation Errors
+
+**WRONG:**
+```ts
+import { error } from '@sveltejs/kit';
+
+export const actions = {
+  default: async ({ request }) => {
+    if (!email?.toString().includes('@')) {
+      throw error(400, 'Invalid email'); // Shows error page!
+    }
+  }
+};
+```
+
+**CORRECT:**
+```ts
+import { fail } from '@sveltejs/kit';
+
+export const actions = {
+  default: async ({ request }) => {
+    const data = await request.formData();
+    const email = data.get('email')?.toString() ?? '';
+
+    if (!email.includes('@')) {
+      return fail(400, {
+        error: 'Invalid email address',
+        email // Return for repopulation
+      });
+    }
+
+    return { success: true };
+  }
+};
+```
+
+### Use throw error() for Unexpected Errors
+
+```ts
+import { fail, error } from '@sveltejs/kit';
+
+export const actions = {
+  default: async ({ request }) => {
+    const data = await request.formData();
+
+    // Validation - use fail()
+    if (!data.get('title')) {
+      return fail(400, { error: 'Title is required' });
+    }
+
+    try {
+      await database.save(data);
+      return { success: true };
+    } catch (e) {
+      // Unexpected error - use throw
+      throw error(500, 'Unable to save. Please try again later.');
+    }
+  }
+};
+```
+
+### Structured Validation Responses
+
+```ts
+interface FormErrors {
+  email?: string;
+  password?: string;
+}
+
+export const actions = {
+  register: async ({ request }) => {
+    const data = await request.formData();
+    const errors: FormErrors = {};
+
+    if (!email) errors.email = 'Email is required';
+    if (password.length < 8) errors.password = 'Password must be at least 8 characters';
+
+    if (Object.keys(errors).length > 0) {
+      return fail(400, { errors, values: { email } });
+    }
+
+    return { success: true };
+  }
+};
+```
+
+### Handle in Component
+
+```svelte
+<script lang="ts">
+  import type { PageProps } from './$types';
+  import { enhance } from '$app/forms';
+
+  let { form }: PageProps = $props();
+</script>
+
+<form method="POST" action="?/register" use:enhance>
+  <label>
+    Email
+    <input name="email" value={form?.values?.email ?? ''} />
+    {#if form?.errors?.email}
+      <span class="error">{form.errors.email}</span>
+    {/if}
+  </label>
+  <button type="submit">Register</button>
+</form>
+```
+
+### Error Response Summary
+
+| Situation | Function | Result |
+|-----------|----------|--------|
+| Missing field | `fail(400, {...})` | Form state preserved |
+| Invalid format | `fail(400, {...})` | Form state preserved |
+| Not found | `throw error(404, ...)` | Error page |
+| Server crash | `throw error(500, ...)` | Error page |
+| Auth required | `throw redirect(303, ...)` | Redirect |
+
+---
+
+## SSR State Isolation
+
+Shared server state persists across requests, potentially leaking data between users.
+
+### Dangerous: Module-Level State
+
+**WRONG:**
+```ts
+// +page.server.ts
+let currentUser = null; // SHARED ACROSS ALL REQUESTS!
+
+export const load = async ({ locals }) => {
+  currentUser = locals.user; // User B overwrites User A
+  return { user: currentUser };
+};
+```
+
+**CORRECT:**
+```ts
+export const load = async ({ locals }) => {
+  return { user: locals.user }; // Each request gets its own locals
+};
+```
+
+### Dangerous: Global Stores
+
+**WRONG:**
+```ts
+// stores.svelte.ts
+export const user = $state<User | null>(null); // Server-side singleton!
+```
+
+**CORRECT: Use locals and return data from load**
+```ts
+// +layout.server.ts
+export const load = async ({ locals }) => {
+  return { user: locals.user };
+};
+```
+
+### Safe Patterns
+
+**Pattern 1: Use locals**
+```ts
+// hooks.server.ts
+export const handle = async ({ event, resolve }) => {
+  event.locals.user = await authenticate(event);
+  event.locals.requestId = crypto.randomUUID();
+  return resolve(event);
+};
+
+// +page.server.ts
+export const load = async ({ locals }) => {
+  return { user: locals.user };
+};
+```
+
+**Pattern 2: Context for Component Trees**
+```svelte
+<!-- +layout.svelte -->
+<script lang="ts">
+  import { setContext } from 'svelte';
+  import type { LayoutProps } from './$types';
+
+  let { data, children }: LayoutProps = $props();
+
+  setContext('user', {
+    get current() { return data.user; }
+  });
+</script>
+
+{@render children()}
+```
+
+**Pattern 3: Client-Only State**
+```ts
+// stores.svelte.ts
+import { browser } from '$app/environment';
+
+function createClientStore() {
+  if (!browser) return { value: null };
+  const state = $state({ value: null });
+  return state;
+}
+
+export const clientState = createClientStore();
+```
+
+### SSR Safety Checklist
+
+- [ ] No module-level `let` variables that store user data
+- [ ] No global `$state` that gets set during SSR
+- [ ] No singleton service classes with mutable state
+- [ ] All user-specific data flows through `locals`
+- [ ] All page data comes from load function returns

.agents/skills/svelte5-best-practices/references/typescript.md

@@ -0,0 +1,305 @@
+# Svelte 5 TypeScript Reference
+
+## Table of Contents
+- [Props Typing](#props-typing)
+- [Generic Components](#generic-components)
+
+---
+
+## Props Typing
+
+`$props()` requires specific patterns for TypeScript typing.
+
+### Basic Props Typing
+
+**Inline typing:**
+```svelte
+<script lang="ts">
+  let { name, count = 0 }: { name: string; count?: number } = $props();
+</script>
+```
+
+**Interface typing (recommended):**
+```svelte
+<script lang="ts">
+  interface Props {
+    name: string;
+    count?: number;
+    disabled?: boolean;
+  }
+
+  let { name, count = 0, disabled = false }: Props = $props();
+</script>
+```
+
+### Children and Snippets Typing
+
+```svelte
+<script lang="ts">
+  import type { Snippet } from 'svelte';
+
+  interface Props {
+    children: Snippet;                    // Required children
+    header?: Snippet;                     // Optional snippet
+    row: Snippet<[data: RowData]>;       // Snippet with parameter
+    cell?: Snippet<[value: string, index: number]>;  // Multiple params
+  }
+
+  interface RowData { id: number; name: string; }
+
+  let { children, header, row, cell }: Props = $props();
+</script>
+```
+
+### Callback Props Typing
+
+```svelte
+<script lang="ts">
+  interface Props {
+    value: string;
+    onchange?: (value: string) => void;
+    onsubmit?: (data: FormData) => Promise<void>;
+    onclick?: (event: MouseEvent) => void;
+  }
+
+  let { value, onchange, onsubmit, onclick }: Props = $props();
+</script>
+```
+
+### Rest Props with HTML Attributes
+
+```svelte
+<script lang="ts">
+  import type { HTMLButtonAttributes } from 'svelte/elements';
+
+  interface Props extends HTMLButtonAttributes {
+    variant?: 'primary' | 'secondary';
+    loading?: boolean;
+  }
+
+  let { variant = 'primary', loading = false, ...rest }: Props = $props();
+</script>
+
+<button class={variant} disabled={loading} {...rest}>
+  {#if loading}Loading...{:else}{@render children?.()}{/if}
+</button>
+```
+
+### Input Element Props
+
+```svelte
+<script lang="ts">
+  import type { HTMLInputAttributes } from 'svelte/elements';
+
+  interface Props extends Omit<HTMLInputAttributes, 'value'> {
+    value?: string;
+    label: string;
+    error?: string;
+  }
+
+  let { value = $bindable(''), label, error, ...rest }: Props = $props();
+</script>
+```
+
+### Union Type Props
+
+```svelte
+<script lang="ts">
+  type ButtonVariant = 'primary' | 'secondary' | 'danger';
+  type ButtonSize = 'sm' | 'md' | 'lg';
+
+  interface Props {
+    variant?: ButtonVariant;
+    size?: ButtonSize;
+    children: Snippet;
+  }
+
+  let { variant = 'primary', size = 'md', children }: Props = $props();
+</script>
+
+<button class="{variant} {size}">{@render children()}</button>
+```
+
+### Discriminated Union Props
+
+```svelte
+<script lang="ts">
+  type Props =
+    | { type: 'link'; href: string; children: Snippet }
+    | { type: 'button'; onclick: () => void; children: Snippet };
+
+  let props: Props = $props();
+</script>
+
+{#if props.type === 'link'}
+  <a href={props.href}>{@render props.children()}</a>
+{:else}
+  <button onclick={props.onclick}>{@render props.children()}</button>
+{/if}
+```
+
+---
+
+## Generic Components
+
+Svelte 5 uses the `generics` attribute for type-safe reusable components.
+
+### Basic Generic Component
+
+```svelte
+<!-- List.svelte -->
+<script lang="ts" generics="T">
+  interface Props {
+    items: T[];
+    children: import('svelte').Snippet<[item: T, index: number]>;
+  }
+
+  let { items, children }: Props = $props();
+</script>
+
+<ul>
+  {#each items as item, index}
+    <li>{@render children(item, index)}</li>
+  {/each}
+</ul>
+
+<!-- Usage -->
+<script lang="ts">
+  import List from './List.svelte';
+
+  interface User { id: number; name: string; }
+  let users: User[] = $state([{ id: 1, name: 'Alice' }]);
+</script>
+
+<List items={users}>
+  {#snippet children(user, index)}
+    <span>{index + 1}. {user.name}</span> <!-- Fully typed! -->
+  {/snippet}
+</List>
+```
+
+### Multiple Type Parameters
+
+```svelte
+<script lang="ts" generics="K, V">
+  interface Props {
+    entries: [K, V][];
+    renderKey: import('svelte').Snippet<[key: K]>;
+    renderValue: import('svelte').Snippet<[value: V]>;
+  }
+
+  let { entries, renderKey, renderValue }: Props = $props();
+</script>
+
+<dl>
+  {#each entries as [key, value]}
+    <dt>{@render renderKey(key)}</dt>
+    <dd>{@render renderValue(value)}</dd>
+  {/each}
+</dl>
+```
+
+### Constrained Generics
+
+```svelte
+<script lang="ts" generics="T extends { id: string | number }">
+  interface Props {
+    items: T[];
+    selected?: T;
+    onselect?: (item: T) => void;
+    children: import('svelte').Snippet<[item: T, isSelected: boolean]>;
+  }
+
+  let { items, selected, onselect, children }: Props = $props();
+</script>
+
+{#each items as item}
+  <div
+    class:selected={selected?.id === item.id}
+    onclick={() => onselect?.(item)}
+  >
+    {@render children(item, selected?.id === item.id)}
+  </div>
+{/each}
+```
+
+### Generic with Default Type
+
+```svelte
+<script lang="ts" generics="T = Record<string, unknown>">
+  interface Props {
+    data: T[];
+    columns: (keyof T)[];
+  }
+
+  let { data, columns }: Props = $props();
+</script>
+```
+
+### Generic Select Component
+
+```svelte
+<script lang="ts" generics="T">
+  interface Props {
+    options: T[];
+    value?: T;
+    getLabel: (option: T) => string;
+    getValue: (option: T) => string;
+    onchange?: (selected: T | undefined) => void;
+    placeholder?: string;
+  }
+
+  let {
+    options,
+    value = $bindable(),
+    getLabel,
+    getValue,
+    onchange,
+    placeholder = 'Select...'
+  }: Props = $props();
+
+  function handleChange(e: Event) {
+    const selectedValue = (e.target as HTMLSelectElement).value;
+    const selected = options.find(o => getValue(o) === selectedValue);
+    value = selected;
+    onchange?.(selected);
+  }
+</script>
+
+<select onchange={handleChange}>
+  <option value="">{placeholder}</option>
+  {#each options as option}
+    <option
+      value={getValue(option)}
+      selected={value && getValue(value) === getValue(option)}
+    >
+      {getLabel(option)}
+    </option>
+  {/each}
+</select>
+```
+
+### Generic Async Component
+
+```svelte
+<script lang="ts" generics="T">
+  import type { Snippet } from 'svelte';
+
+  interface Props {
+    promise: Promise<T>;
+    loading?: Snippet;
+    error?: Snippet<[error: Error]>;
+    children: Snippet<[data: T]>;
+  }
+
+  let { promise, loading, error, children }: Props = $props();
+</script>
+
+{#await promise}
+  {#if loading}{@render loading()}{:else}<p>Loading...</p>{/if}
+{:then data}
+  {@render children(data)}
+{:catch err}
+  {#if error}{@render error(err)}{:else}<p>Error: {err.message}</p>{/if}
+{/await}
+```

.agents/skills/sveltekit-data-flow/README.md

@@ -0,0 +1,17 @@
+# Sveltekit Data Flow
+
+SvelteKit data flow guidance. Use for load functions, form actions,
+and server/client data. Covers +page.server.ts vs +page.ts,
+serialization, fail(), redirect(), error().
+
+## Structure
+
+- `SKILL.md` - Main skill instructions
+- `references/` - Detailed documentation loaded as needed
+- `scripts/` - Executable code for deterministic operations
+- `assets/` - Templates, images, or other resources
+
+## Usage
+
+This skill is automatically discovered by Claude when relevant to the
+task.

.agents/skills/sveltekit-data-flow/SKILL.md

@@ -0,0 +1,79 @@
+---
+name: sveltekit-data-flow
+# IMPORTANT: Keep description on ONE line for Claude Code compatibility
+# prettier-ignore
+description: SvelteKit data flow guidance. Use for load functions, form actions, server/client data, and invalidation. Covers +page.server.ts vs +page.ts, serialization, fail(), redirect(), error(), invalidateAll().
+---
+
+# SvelteKit Data Flow
+
+## Quick Start
+
+**Which file?** Server-only (DB/secrets): `+page.server.ts` |
+Universal (runs both): `+page.ts` | API: `+server.ts`
+
+**Load decision:** Need server resources? → server load | Need client
+APIs? → universal load
+
+**Form actions:** Always `+page.server.ts`. Return `fail()` for
+errors, throw `redirect()` to navigate, throw `error()` for failures.
+
+## Example
+
+```typescript
+// +page.server.ts
+import { fail, redirect } from '@sveltejs/kit';
+
+export const load = async ({ locals }) => {
+	const user = await db.users.get(locals.userId);
+	return { user }; // Must be JSON-serializable
+};
+
+export const actions = {
+	default: async ({ request }) => {
+		const data = await request.formData();
+		const email = data.get('email');
+
+		if (!email) return fail(400, { email, missing: true });
+
+		await updateEmail(email);
+		throw redirect(303, '/success');
+	},
+};
+```
+
+## Reference Files
+
+- [load-functions.md](references/load-functions.md) - Server vs
+  universal
+- [form-actions.md](references/form-actions.md) - Form handling
+  patterns
+- [serialization.md](references/serialization.md) - What can/can't
+  serialize
+- [error-redirect-handling.md](references/error-redirect-handling.md) -
+  fail/redirect/error
+- [client-auth-invalidation.md](references/client-auth-invalidation.md) -
+  invalidateAll() after client-side auth
+
+## Notes
+
+- Server load → universal load via `data` param | ALWAYS
+  `throw redirect()/error()`
+- No class instances/functions from server load (not serializable)
+- **Last verified:** 2025-01-11
+
+<!--
+PROGRESSIVE DISCLOSURE GUIDELINES:
+- Keep this file ~50 lines total (max ~150 lines)
+- Use 1-2 code blocks only (recommend 1)
+- Keep description <200 chars for Level 1 efficiency
+- Move detailed docs to references/ for Level 3 loading
+- This is Level 2 - quick reference ONLY, not a manual
+
+LLM WORKFLOW (when editing this file):
+1. Write/edit SKILL.md
+2. Format (if formatter available)
+3. Run: claude-skills-cli validate <path>
+4. If multi-line description warning: run claude-skills-cli doctor <path>
+5. Validate again to confirm
+-->

.agents/skills/sveltekit-data-flow/references/client-auth-invalidation.md

@@ -0,0 +1,125 @@
+# Client-Side Auth Invalidation
+
+When using client-side auth libraries (Better Auth, Firebase, Supabase client),
+layout server data doesn't auto-refresh after login/logout.
+
+## The Problem
+
+```typescript
+// signin/+page.svelte - BROKEN
+async function handle_signin() {
+  await auth_client.signIn.email({ email, password });
+  goto('/');  // Layout still shows "logged out"
+}
+```
+
+**Why?** Client-side navigation (`goto()`) doesn't re-run server load functions.
+The session cookie is set, but `+layout.server.ts` data is stale.
+
+## Solution A: Inline Invalidation (Simple)
+
+Call `invalidateAll()` after auth state change:
+
+```typescript
+// signin/+page.svelte
+import { goto, invalidateAll } from '$app/navigation';
+
+async function handle_signin() {
+  const result = await auth_client.signIn.email({ email, password });
+  if (result.error) return;
+
+  await invalidateAll();  // Re-runs ALL load functions
+  goto('/');
+}
+
+// signout handler
+async function handle_signout() {
+  await auth_client.signOut();
+  await invalidateAll();
+}
+```
+
+**Use when:** Single auth entry point, simple apps.
+
+## Solution B: Auth State Listener (Robust)
+
+Set up a listener in root layout that auto-invalidates on auth changes:
+
+```svelte
+<!-- +layout.svelte -->
+<script>
+  import { invalidateAll } from '$app/navigation';
+  import { onMount } from 'svelte';
+  import { auth_client } from '$lib/auth-client';
+
+  onMount(() => {
+    // Listen for auth state changes
+    const unsubscribe = auth_client.onAuthStateChange(() => {
+      invalidateAll();
+    });
+
+    return unsubscribe;
+  });
+</script>
+```
+
+**Use when:** Multiple auth flows (OAuth, magic links, etc.), complex apps.
+
+## Common Mistakes
+
+### Not awaiting invalidateAll()
+
+```typescript
+// WRONG - race condition
+invalidateAll();
+goto('/');
+
+// RIGHT - wait for data refresh
+await invalidateAll();
+goto('/');
+```
+
+### Destructuring layout data
+
+```svelte
+<!-- WRONG - static snapshot -->
+<script>
+  let { data } = $props();
+  const { user } = data;  // Never updates after invalidateAll()
+</script>
+
+<!-- RIGHT - reactive access -->
+<script>
+  let { data } = $props();
+</script>
+
+{data.user?.email}
+```
+
+## When invalidateAll() Runs
+
+Per [Svelte docs](https://svelte.dev/tutorial/kit/invalidate-all):
+
+> `invalidateAll()` is the nuclear option - it re-runs ALL load functions
+> for the current page, regardless of dependencies.
+
+This includes:
+- `+layout.server.ts` (all levels)
+- `+layout.ts` (all levels)
+- `+page.server.ts`
+- `+page.ts`
+
+## Comparison with Server-Side Auth
+
+| Approach | Auth Location | Invalidation |
+|----------|--------------|--------------|
+| Form actions | Server (`+page.server.ts`) | Automatic (page reload) |
+| Client auth | Browser (auth_client) | Manual (`invalidateAll()`) |
+
+Form actions with `throw redirect()` cause a full navigation, which
+naturally re-runs load functions. Client-side auth with `goto()` does not.
+
+## See Also
+
+- [error-redirect-handling.md](error-redirect-handling.md) - Server-side redirects
+- [load-functions.md](load-functions.md) - Server vs universal loads

.agents/skills/sveltekit-data-flow/references/error-redirect-handling.md

@@ -0,0 +1,407 @@
+# Error & Redirect Handling: fail(), redirect(), error()
+
+## The Three Ways to Handle Failures
+
+| Function     | When             | Must Throw? | Use Case                              |
+| ------------ | ---------------- | ----------- | ------------------------------------- |
+| `fail()`     | Validation error | No (return) | Form validation errors                |
+| `redirect()` | Navigate user    | **YES**     | After successful action               |
+| `error()`    | Fatal error      | **YES**     | Unauthorized, not found, server error |
+
+## fail() - Validation Errors
+
+**Return** (don't throw) from form actions to show validation errors:
+
+```typescript
+import { fail } from '@sveltejs/kit';
+
+export const actions = {
+	default: async ({ request }) => {
+		const data = await request.formData();
+		const email = data.get('email');
+
+		// Validation failed - return fail()
+		if (!email || !email.includes('@')) {
+			return fail(400, {
+				email,
+				error: 'Invalid email',
+				missing: !email,
+			});
+		}
+
+		// Success - process and maybe redirect
+		await processEmail(email);
+		throw redirect(303, '/success');
+	},
+};
+```
+
+```svelte
+<!-- +page.svelte -->
+<script>
+	export let form; // Contains fail() return value
+</script>
+
+{#if form?.error}
+	<p class="error">{form.error}</p>
+{/if}
+
+<form method="POST">
+	<input name="email" value={form?.email ?? ''} />
+
+	{#if form?.missing}
+		<span>Email is required</span>
+	{/if}
+
+	<button>Submit</button>
+</form>
+```
+
+**Key points:**
+
+- **Return** fail() (don't throw)
+- Status code (400 = bad request)
+- Return validation errors + form data to repopulate fields
+- Accessible via `form` prop in page component
+- Page stays on same URL
+
+## redirect() - Navigation
+
+**Throw** redirect() to navigate user to another page:
+
+```typescript
+import { redirect } from '@sveltejs/kit';
+
+export const actions = {
+	login: async ({ request, cookies }) => {
+		const data = await request.formData();
+
+		const user = await authenticate(data);
+
+		if (!user) {
+			return fail(401, { error: 'Invalid credentials' });
+		}
+
+		cookies.set('session', user.sessionToken, { path: '/' });
+
+		// Success - redirect to dashboard
+		throw redirect(303, '/dashboard'); // MUST throw
+	},
+};
+```
+
+**Status codes:**
+
+- `303` - See Other (recommended for POST → GET redirect)
+- `301` - Moved Permanently
+- `302` - Found (temporary redirect)
+- `307` - Temporary Redirect (preserves method)
+- `308` - Permanent Redirect (preserves method)
+
+**Use 303** for most cases (especially after form submission).
+
+**Key points:**
+
+- **MUST throw** (not return)
+- Use status 303 for form actions
+- Can redirect to external URLs
+- Can use relative paths: `throw redirect(303, '..')`
+
+## error() - Fatal Errors
+
+**Throw** error() for unrecoverable errors (auth, not found, server
+error):
+
+```typescript
+import { error } from '@sveltejs/kit';
+
+export const load = async ({ params, locals }) => {
+	const post = await db.query.posts.findFirst({
+		where: eq(posts.id, params.id),
+	});
+
+	if (!post) {
+		throw error(404, 'Post not found'); // MUST throw
+	}
+
+	if (post.authorId !== locals.userId) {
+		throw error(403, 'Forbidden'); // MUST throw
+	}
+
+	return { post };
+};
+```
+
+**Common status codes:**
+
+- `400` - Bad Request
+- `401` - Unauthorized (not logged in)
+- `403` - Forbidden (logged in but no permission)
+- `404` - Not Found
+- `500` - Internal Server Error
+
+**With custom error page:**
+
+```typescript
+// src/routes/posts/[id]/+page.server.ts
+import { error } from '@sveltejs/kit';
+
+export const load = async ({ params }) => {
+	const post = await getPost(params.id);
+
+	if (!post) {
+		throw error(404, {
+			message: 'Post not found',
+			postId: params.id,
+		});
+	}
+
+	return { post };
+};
+```
+
+```svelte
+<!-- src/routes/posts/[id]/+error.svelte -->
+<script>
+	import { page } from '$app/stores';
+</script>
+
+<h1>{$page.status}: {$page.error.message}</h1>
+
+{#if $page.error.postId}
+	<p>Could not find post with ID: {$page.error.postId}</p>
+{/if}
+```
+
+**Key points:**
+
+- **MUST throw** (not return)
+- Renders closest `+error.svelte` file
+- Accessible via `$page.status` and `$page.error`
+- Stops load function execution
+- Use for authorization, not found, server errors
+
+## Common Mistakes
+
+### ❌ Not Throwing redirect()
+
+```typescript
+// WRONG
+export const actions = {
+	default: async () => {
+		redirect(303, '/home'); // DOESN'T WORK
+	},
+};
+
+// RIGHT
+export const actions = {
+	default: async () => {
+		throw redirect(303, '/home'); // MUST throw
+	},
+};
+```
+
+### ❌ Not Throwing error()
+
+```typescript
+// WRONG
+export const load = async () => {
+	error(404, 'Not found'); // DOESN'T WORK
+};
+
+// RIGHT
+export const load = async () => {
+	throw error(404, 'Not found'); // MUST throw
+};
+```
+
+### ❌ Throwing fail()
+
+```typescript
+// WRONG
+export const actions = {
+	default: async () => {
+		throw fail(400, { error: 'Bad' }); // Don't throw
+	},
+};
+
+// RIGHT
+export const actions = {
+	default: async () => {
+		return fail(400, { error: 'Bad' }); // Return
+	},
+};
+```
+
+### ❌ Catching redirect Without Rethrowing
+
+```typescript
+// WRONG
+export const actions = {
+	default: async () => {
+		try {
+			await doSomething();
+			throw redirect(303, '/success');
+		} catch (e) {
+			console.error(e); // Catches redirect - it won't work!
+			return fail(500, { error: 'Failed' });
+		}
+	},
+};
+
+// RIGHT
+import { isRedirect } from '@sveltejs/kit';
+
+export const actions = {
+	default: async () => {
+		try {
+			await doSomething();
+			throw redirect(303, '/success');
+		} catch (e) {
+			if (isRedirect(e)) throw e; // Rethrow redirect
+			console.error(e);
+			return fail(500, { error: 'Failed' });
+		}
+	},
+};
+```
+
+## Decision Tree
+
+```
+Problem in form action?
+├─ Validation error (show to user) → return fail(400, { errors })
+├─ Success (navigate) → throw redirect(303, '/success')
+└─ Fatal error (auth, not found) → throw error(403, 'Forbidden')
+
+Problem in load function?
+├─ Data not found → throw error(404, 'Not found')
+├─ Unauthorized → throw error(401, 'Unauthorized')
+├─ Forbidden → throw error(403, 'Forbidden')
+└─ Server error → throw error(500, 'Server error')
+```
+
+## Patterns
+
+### Pattern 1: Validate, Process, Redirect
+
+```typescript
+export const actions = {
+	create: async ({ request }) => {
+		const data = await request.formData();
+
+		// 1. Validate
+		if (!isValid(data)) {
+			return fail(400, { errors: getErrors(data) });
+		}
+
+		// 2. Process
+		const post = await createPost(data);
+
+		// 3. Redirect
+		throw redirect(303, `/posts/${post.id}`);
+	},
+};
+```
+
+### Pattern 2: Check Auth, Load Data
+
+```typescript
+export const load = async ({ locals, params }) => {
+	// 1. Check auth
+	if (!locals.user) {
+		throw error(401, 'Please log in');
+	}
+
+	// 2. Load data
+	const post = await getPost(params.id);
+
+	if (!post) {
+		throw error(404, 'Post not found');
+	}
+
+	// 3. Check permission
+	if (post.authorId !== locals.user.id) {
+		throw error(403, 'Not your post');
+	}
+
+	return { post };
+};
+```
+
+### Pattern 3: Conditional Redirect
+
+```typescript
+export const load = async ({ locals }) => {
+	// Redirect if already logged in
+	if (locals.user) {
+		throw redirect(303, '/dashboard');
+	}
+
+	return {}; // Show login page
+};
+```
+
+## Summary Table
+
+|                      | fail()            | redirect()      | error()         |
+| -------------------- | ----------------- | --------------- | --------------- |
+| **Throw or return?** | Return            | **Throw**       | **Throw**       |
+| **Use in**           | Form actions      | Actions & load  | Actions & load  |
+| **Purpose**          | Validation errors | Navigate        | Fatal errors    |
+| **Status codes**     | 400-499           | 301-308         | 400-599         |
+| **Accessible via**   | `form` prop       | N/A (navigates) | `+error.svelte` |
+| **Stays on page?**   | Yes               | No (navigates)  | No (error page) |
+| **Example**          | Invalid email     | After save      | Not found       |
+
+## Client-Side Navigation After Auth
+
+When using client-side auth (e.g., Better Auth client), **always use `goto()` with `invalidateAll: true`** to ensure layout data refreshes:
+
+```svelte
+<script>
+	import { goto } from '$app/navigation';
+	import { auth_client } from '$lib/auth-client';
+
+	async function handle_signin() {
+		const result = await auth_client.signIn.email({ email, password });
+
+		if (!result.error) {
+			// ✅ CORRECT: invalidateAll ensures layout load functions re-run
+			await goto('/dashboard', { invalidateAll: true });
+		}
+	}
+</script>
+```
+
+### ❌ Common Mistake: Separate invalidateAll + goto
+
+```typescript
+// WRONG: Data might not refresh before navigation
+await invalidateAll();
+goto('/dashboard');
+
+// ALSO WRONG: goto doesn't wait for invalidation
+await invalidateAll();
+await goto('/dashboard');
+```
+
+### ✅ Correct Pattern
+
+```typescript
+// RIGHT: Single call with invalidateAll option
+await goto('/dashboard', { invalidateAll: true });
+```
+
+**Why this matters:** After client-side auth, cookies are set but the root layout's `load` function (which typically checks `auth.api.getSession()`) has cached data. Using `invalidateAll: true` forces all load functions to re-run with the new session cookie.
+
+**Note:** Server-side redirects with `throw redirect()` don't have this problem because they trigger a full page load.
+
+## Quick Checklist
+
+- ✅ Using `return fail()` for validation errors?
+- ✅ Using `throw redirect()` (not return) after success?
+- ✅ Using `throw error()` (not return) for fatal errors?
+- ✅ Not catching redirects/errors without rethrowing?
+- ✅ Using status code 303 for POST redirects?
+- ✅ Using `goto(url, { invalidateAll: true })` after client-side auth?

.agents/skills/sveltekit-data-flow/references/form-actions.md

@@ -0,0 +1,316 @@
+# Form Actions
+
+## Basic Pattern
+
+Form actions live in `+page.server.ts` and handle form submissions:
+
+```typescript
+// +page.server.ts
+import { fail, redirect } from '@sveltejs/kit';
+import type { Actions } from './$types';
+
+export const actions: Actions = {
+	default: async ({ request }) => {
+		const data = await request.formData();
+		const email = data.get('email');
+		const password = data.get('password');
+
+		if (!email) {
+			return fail(400, { email, missing: true });
+		}
+
+		await login(email, password);
+		throw redirect(303, '/dashboard');
+	},
+};
+```
+
+```svelte
+<!-- +page.svelte -->
+<script>
+	export let form; // Contains return value from action
+</script>
+
+<form method="POST">
+	<input name="email" value={form?.email ?? ''} />
+	{#if form?.missing}
+		<p class="error">Email is required</p>
+	{/if}
+
+	<button>Login</button>
+</form>
+```
+
+## Named Actions
+
+```typescript
+export const actions: Actions = {
+	login: async ({ request }) => {
+		// Handle login
+	},
+
+	register: async ({ request }) => {
+		// Handle registration
+	},
+};
+```
+
+```svelte
+<form method="POST" action="?/login">...</form>
+<form method="POST" action="?/register">...</form>
+```
+
+## Return Values
+
+### Option 1: fail() - Show Error to User
+
+```typescript
+import { fail } from '@sveltejs/kit';
+
+export const actions = {
+	default: async ({ request }) => {
+		const data = await request.formData();
+
+		if (!isValid(data)) {
+			return fail(400, {
+				error: 'Invalid data',
+				fields: Object.fromEntries(data), // Preserve input
+			});
+		}
+
+		// Success - no return needed
+	},
+};
+```
+
+### Option 2: redirect() - Navigate After Success
+
+```typescript
+import { redirect } from '@sveltejs/kit';
+
+export const actions = {
+	default: async ({ request }) => {
+		await processForm(request);
+		throw redirect(303, '/success'); // MUST throw
+	},
+};
+```
+
+### Option 3: error() - Fatal Error
+
+```typescript
+import { error } from '@sveltejs/kit';
+
+export const actions = {
+	default: async ({ request }) => {
+		const user = await getCurrentUser();
+
+		if (!user) {
+			throw error(401, 'Unauthorized'); // MUST throw
+		}
+
+		// Process...
+	},
+};
+```
+
+## Progressive Enhancement
+
+Form works without JavaScript:
+
+```svelte
+<script>
+	import { enhance } from '$app/forms';
+</script>
+
+<form method="POST" use:enhance>
+	<!-- Works with or without JS -->
+</form>
+```
+
+With custom handling:
+
+```svelte
+<form
+	method="POST"
+	use:enhance={({ formData, cancel }) => {
+		// Before submit
+		formData.append('timestamp', Date.now().toString());
+
+		return async ({ result, update }) => {
+			// After response
+			if (result.type === 'success') {
+				await update(); // Update form prop
+			}
+		};
+	}}
+>
+	...
+</form>
+```
+
+## Validation Pattern
+
+```typescript
+import { fail } from '@sveltejs/kit';
+import { z } from 'zod';
+
+const schema = z.object({
+	email: z.string().email(),
+	password: z.string().min(8),
+});
+
+export const actions = {
+	default: async ({ request }) => {
+		const data = await request.formData();
+		const rawData = {
+			email: data.get('email'),
+			password: data.get('password'),
+		};
+
+		const result = schema.safeParse(rawData);
+
+		if (!result.success) {
+			return fail(400, {
+				errors: result.error.flatten().fieldErrors,
+				data: rawData,
+			});
+		}
+
+		// result.data is validated
+		await createUser(result.data);
+		throw redirect(303, '/welcome');
+	},
+};
+```
+
+## Common Mistakes
+
+### ❌ Not Throwing redirect/error
+
+```typescript
+// WRONG
+export const actions = {
+	default: async () => {
+		redirect(303, '/home'); // DOESN'T WORK - must throw
+	},
+};
+
+// RIGHT
+export const actions = {
+	default: async () => {
+		throw redirect(303, '/home');
+	},
+};
+```
+
+### ❌ Catching redirect Without Rethrowing
+
+```typescript
+// WRONG
+export const actions = {
+	default: async () => {
+		try {
+			await doSomething();
+			throw redirect(303, '/success');
+		} catch (e) {
+			console.error(e); // Catches redirect!
+		}
+	},
+};
+
+// RIGHT
+export const actions = {
+	default: async () => {
+		try {
+			await doSomething();
+			throw redirect(303, '/success');
+		} catch (e) {
+			if (e instanceof Redirect) throw e; // Rethrow
+			console.error(e);
+		}
+	},
+};
+```
+
+### ❌ Returning non-serializable data
+
+```typescript
+// WRONG
+export const actions = {
+	default: async () => {
+		return { date: new Date() }; // Date is not serializable
+	},
+};
+
+// RIGHT
+export const actions = {
+	default: async () => {
+		return { date: new Date().toISOString() };
+	},
+};
+```
+
+## File Upload
+
+```typescript
+export const actions = {
+	default: async ({ request }) => {
+		const data = await request.formData();
+		const file = data.get('file') as File;
+
+		if (!file || file.size === 0) {
+			return fail(400, { error: 'No file uploaded' });
+		}
+
+		const bytes = await file.arrayBuffer();
+		const buffer = Buffer.from(bytes);
+
+		await saveFile(buffer, file.name);
+		throw redirect(303, '/uploads');
+	},
+};
+```
+
+```svelte
+<form method="POST" enctype="multipart/form-data">
+	<input type="file" name="file" required />
+	<button>Upload</button>
+</form>
+```
+
+## Form Prop in Page
+
+```svelte
+<script>
+	export let data; // From load function
+	export let form; // From action return value
+</script>
+
+{#if form?.error}
+	<div class="error">{form.error}</div>
+{/if}
+
+{#if form?.success}
+	<div class="success">Success!</div>
+{/if}
+
+<form method="POST">
+	<input name="email" value={form?.email ?? data.email ?? ''} />
+	{#if form?.errors?.email}
+		<p>{form.errors.email}</p>
+	{/if}
+
+	<button>Submit</button>
+</form>
+```
+
+## Key Rules
+
+1. ✅ Actions must be in `+page.server.ts` (not `+page.ts`)
+2. ✅ ALWAYS throw `redirect()` and `error()` (not return)
+3. ✅ Return `fail()` for validation errors
+4. ✅ Return only serializable data
+5. ✅ Don't catch redirects/errors without rethrowing
+6. ✅ Use `enhance` for progressive enhancement
+7. ✅ Access FormData with `data.get('fieldName')`

.agents/skills/sveltekit-data-flow/references/load-functions.md

@@ -0,0 +1,292 @@
+# Load Functions: Server vs Universal
+
+## Decision Matrix
+
+| Need                                | Use            | File              |
+| ----------------------------------- | -------------- | ----------------- |
+| Database access                     | Server load    | `+page.server.ts` |
+| Secrets/env vars                    | Server load    | `+page.server.ts` |
+| Server-only packages                | Server load    | `+page.server.ts` |
+| Browser APIs (window, localStorage) | Universal load | `+page.ts`        |
+| Client-side fetch                   | Universal load | `+page.ts`        |
+| Runs on both                        | Universal load | `+page.ts`        |
+
+## Server Load (+page.server.ts)
+
+**When:** Need server-only resources (DB, secrets, server APIs)
+
+**Runs:** Only on server (never in browser)
+
+```typescript
+// src/routes/profile/+page.server.ts
+import type { PageServerLoad } from './$types';
+import { db } from '$lib/server/database';
+
+export const load: PageServerLoad = async ({ locals, params }) => {
+	// Access server-only resources
+	const user = await db.query.users.findFirst({
+		where: eq(users.id, locals.userId),
+	});
+
+	const posts = await db.query.posts.findMany({
+		where: eq(posts.authorId, user.id),
+	});
+
+	// Must return serializable data
+	return {
+		user: {
+			id: user.id,
+			name: user.name,
+			email: user.email,
+		},
+		posts,
+	};
+};
+```
+
+**Key points:**
+
+- Runs only on server
+- Can access `$lib/server/*` imports
+- Can use secrets from `env` safely
+- Return values must be JSON-serializable
+- Output is automatically passed to universal load
+
+## Universal Load (+page.ts)
+
+**When:** Need to run on both server and client, or need browser APIs
+
+**Runs:** Server (during SSR) AND client (during navigation)
+
+```typescript
+// src/routes/dashboard/+page.ts
+import type { PageLoad } from './$types';
+
+export const load: PageLoad = async ({ data, fetch }) => {
+	// `data` comes from +page.server.ts if it exists
+	const { user } = data;
+
+	// Fetch additional data (works on both server and client)
+	const response = await fetch('/api/stats');
+	const stats = await response.json();
+
+	// Can access browser APIs (but check if in browser first)
+	const theme =
+		typeof window !== 'undefined'
+			? localStorage.getItem('theme')
+			: null;
+
+	return {
+		user,
+		stats,
+		theme,
+	};
+};
+```
+
+**Key points:**
+
+- Runs on both server AND client
+- Receives server load output as `data` parameter
+- Use SvelteKit's `fetch` (automatically handles SSR)
+- Check `typeof window !== 'undefined'` for browser APIs
+- Cannot import from `$lib/server/*`
+
+## Data Flow
+
+```
+Request → Server Load (+page.server.ts)
+            ↓ (returns { user })
+        Universal Load (+page.ts)
+            ↓ (receives data: { user }, returns { user, stats })
+        Page Component (+page.svelte)
+            ↓ (receives data: { user, stats })
+```
+
+**Example:**
+
+```typescript
+// +page.server.ts
+export const load = async () => {
+  return { serverData: 'from server' };
+};
+
+// +page.ts
+export const load = async ({ data }) => {
+  console.log(data.serverData);  // 'from server'
+  return { ...data, clientData: 'from universal' };
+};
+
+// +page.svelte
+<script>
+  export let data;  // { serverData, clientData }
+</script>
+```
+
+## Common Patterns
+
+### Pattern 1: Server + Universal
+
+```typescript
+// +page.server.ts - Fetch sensitive data
+export const load = async ({ locals }) => {
+	const user = await getUser(locals.session);
+	return { user };
+};
+
+// +page.ts - Fetch public data
+export const load = async ({ data, fetch }) => {
+	const publicPosts = await fetch('/api/posts').then((r) => r.json());
+	return { ...data, publicPosts };
+};
+```
+
+### Pattern 2: Conditional Universal Load
+
+```typescript
+// +page.ts
+import { browser } from '$app/environment';
+
+export const load = async ({ fetch }) => {
+	const serverData = await fetch('/api/data').then((r) => r.json());
+
+	// Only run in browser
+	let clientOnlyData = null;
+	if (browser) {
+		clientOnlyData = localStorage.getItem('cache');
+	}
+
+	return { serverData, clientOnlyData };
+};
+```
+
+### Pattern 3: Depends for Revalidation
+
+```typescript
+// +page.ts
+export const load = async ({ fetch, depends }) => {
+	depends('app:posts'); // Invalidate with invalidate('app:posts')
+
+	const posts = await fetch('/api/posts').then((r) => r.json());
+	return { posts };
+};
+
+// Somewhere else:
+import { invalidate } from '$app/navigation';
+invalidate('app:posts'); // Re-runs load function
+```
+
+## Common Mistakes
+
+### ❌ Importing Server Code in Universal Load
+
+```typescript
+// +page.ts - WRONG
+import { db } from '$lib/server/database'; // ERROR - can't import server code
+
+export const load = async () => {
+	const users = await db.query.users.findMany(); // Won't work
+	return { users };
+};
+```
+
+**Fix:** Move to `+page.server.ts`
+
+### ❌ Returning Non-Serializable Data
+
+```typescript
+// +page.server.ts - WRONG
+export const load = async () => {
+	const user = await User.findOne(); // Returns class instance
+	return { user }; // ERROR - class instances aren't serializable
+};
+```
+
+**Fix:** Return plain objects
+
+```typescript
+export const load = async () => {
+	const user = await User.findOne();
+	return {
+		user: {
+			id: user.id,
+			name: user.name,
+			email: user.email,
+		},
+	};
+};
+```
+
+### ❌ Using window/localStorage Without Check
+
+```typescript
+// +page.ts - WRONG
+export const load = async () => {
+	const theme = localStorage.getItem('theme'); // ERROR on server
+	return { theme };
+};
+```
+
+**Fix:** Check for browser
+
+```typescript
+import { browser } from '$app/environment';
+
+export const load = async () => {
+	const theme = browser ? localStorage.getItem('theme') : 'light';
+	return { theme };
+};
+```
+
+## TypeScript
+
+```typescript
+import type { PageServerLoad } from './$types';
+
+export const load: PageServerLoad = async ({
+	locals,
+	params,
+	url,
+}) => {
+	// TypeScript knows return type must be serializable
+	return {
+		user: {
+			id: 1,
+			name: 'Alice',
+		},
+	};
+};
+```
+
+```typescript
+import type { PageLoad } from './$types';
+
+export const load: PageLoad = async ({ data, fetch, params }) => {
+	// `data` is typed from +page.server.ts return type
+	return {
+		...data,
+		extra: 'data',
+	};
+};
+```
+
+## When to Use Which
+
+**Use Server Load when:**
+
+- Need database access
+- Need secrets/environment variables
+- Need server-only npm packages
+- Need to hide implementation details
+
+**Use Universal Load when:**
+
+- Need browser APIs (localStorage, window)
+- Need to fetch public APIs (works on both)
+- Want client-side navigation without server round-trip
+- Data is public and doesn't need server resources
+
+**Use Both when:**
+
+- Server load fetches sensitive data
+- Universal load fetches public data or adds client-side enhancements

.agents/skills/sveltekit-data-flow/references/serialization.md

@@ -0,0 +1,317 @@
+# Serialization: What Can/Can't Be Returned
+
+## The Rule
+
+**Server load functions and form actions must return JSON-serializable
+data.**
+
+Data travels from server → client as JSON. Non-JSON types break.
+
+## ✅ Serializable (Safe)
+
+| Type         | Example                   | Notes                             |
+| ------------ | ------------------------- | --------------------------------- |
+| String       | `"hello"`                 | ✅                                |
+| Number       | `42`, `3.14`              | ✅                                |
+| Boolean      | `true`, `false`           | ✅                                |
+| null         | `null`                    | ✅                                |
+| Array        | `[1, 2, 3]`               | ✅                                |
+| Plain Object | `{ name: 'Alice' }`       | ✅                                |
+| Nested       | `{ user: { posts: [] } }` | ✅ If all values are serializable |
+
+## ❌ NOT Serializable (Breaks)
+
+| Type           | Example        | Why                        | Fix                                          |
+| -------------- | -------------- | -------------------------- | -------------------------------------------- |
+| Date           | `new Date()`   | Becomes string             | Use `.toISOString()`                         |
+| undefined      | `undefined`    | Removed from JSON          | Use `null`                                   |
+| Function       | `() => {}`     | Can't serialize            | Remove or convert to data                    |
+| Class instance | `new User()`   | Only serializes properties | Convert to plain object                      |
+| Map            | `new Map()`    | Becomes `{}`               | Convert to object: `Object.fromEntries(map)` |
+| Set            | `new Set()`    | Becomes `{}`               | Convert to array: `Array.from(set)`          |
+| BigInt         | `123n`         | Error                      | Convert to string                            |
+| Symbol         | `Symbol('id')` | Removed                    | Don't use                                    |
+| RegExp         | `/test/`       | Becomes `{}`               | Convert to string                            |
+| Error          | `new Error()`  | Loses stack                | Extract message/code                         |
+
+## Examples
+
+### ❌ Wrong: Returning Date
+
+```typescript
+// +page.server.ts - WRONG
+export const load = async () => {
+	return {
+		createdAt: new Date(), // Serializes as string, not Date object
+	};
+};
+```
+
+```svelte
+<!-- +page.svelte -->
+<script>
+	export let data;
+	console.log(data.createdAt); // String, not Date
+	console.log(data.createdAt.getTime()); // ERROR - not a Date
+</script>
+```
+
+### ✅ Right: Convert Date to ISO String
+
+```typescript
+// +page.server.ts - RIGHT
+export const load = async () => {
+	const user = await db.users.findFirst();
+
+	return {
+		user: {
+			id: user.id,
+			name: user.name,
+			createdAt: user.createdAt.toISOString(), // Convert to string
+		},
+	};
+};
+```
+
+```svelte
+<!-- +page.svelte -->
+<script>
+	export let data;
+	const createdAt = new Date(data.user.createdAt); // Parse back to Date
+</script>
+```
+
+### ❌ Wrong: Returning Class Instance
+
+```typescript
+// +page.server.ts - WRONG
+class User {
+	constructor(
+		public id: number,
+		public name: string,
+	) {}
+
+	getDisplayName() {
+		return `User: ${this.name}`;
+	}
+}
+
+export const load = async () => {
+	const user = new User(1, 'Alice');
+	return { user }; // Methods are lost during serialization
+};
+```
+
+```svelte
+<script>
+	export let data;
+	console.log(data.user.getDisplayName()); // ERROR - method doesn't exist
+</script>
+```
+
+### ✅ Right: Return Plain Object
+
+```typescript
+// +page.server.ts - RIGHT
+export const load = async () => {
+	const user = await db.users.findFirst();
+
+	return {
+		user: {
+			id: user.id,
+			name: user.name,
+			email: user.email,
+			// Only plain data, no methods
+		},
+	};
+};
+```
+
+### ❌ Wrong: undefined Values
+
+```typescript
+// +page.server.ts - WRONG
+export const load = async () => {
+	return {
+		name: 'Alice',
+		email: undefined, // Removed during JSON.stringify
+	};
+};
+```
+
+```svelte
+<script>
+	export let data;
+	console.log('email' in data); // false - key is missing!
+</script>
+```
+
+### ✅ Right: Use null
+
+```typescript
+// +page.server.ts - RIGHT
+export const load = async () => {
+	return {
+		name: 'Alice',
+		email: null, // Preserved
+	};
+};
+```
+
+### ❌ Wrong: Map/Set
+
+```typescript
+// +page.server.ts - WRONG
+export const load = async () => {
+	const tags = new Set(['svelte', 'typescript']);
+	const metadata = new Map([['version', '1.0']]);
+
+	return {
+		tags, // Becomes {}
+		metadata, // Becomes {}
+	};
+};
+```
+
+### ✅ Right: Convert to Array/Object
+
+```typescript
+// +page.server.ts - RIGHT
+export const load = async () => {
+	const tags = new Set(['svelte', 'typescript']);
+	const metadata = new Map([['version', '1.0']]);
+
+	return {
+		tags: Array.from(tags), // ['svelte', 'typescript']
+		metadata: Object.fromEntries(metadata), // { version: '1.0' }
+	};
+};
+```
+
+## ORM Returns (Drizzle, Prisma)
+
+Most ORMs return plain objects with Date fields:
+
+```typescript
+// +page.server.ts
+export const load = async () => {
+	const user = await db.query.users.findFirst();
+	// user = { id: 1, name: 'Alice', createdAt: Date }
+
+	return {
+		user: {
+			...user,
+			createdAt: user.createdAt.toISOString(), // Convert Date
+		},
+	};
+};
+```
+
+Or use a helper:
+
+```typescript
+function serialize<T extends Record<string, any>>(obj: T): T {
+	return JSON.parse(JSON.stringify(obj)); // Forces serialization
+}
+
+export const load = async () => {
+	const user = await db.query.users.findFirst();
+	return { user: serialize(user) };
+};
+```
+
+## BigInt
+
+```typescript
+// +page.server.ts - WRONG
+export const load = async () => {
+	return {
+		userId: 123456789012345678901234567890n, // ERROR - can't serialize
+	};
+};
+
+// +page.server.ts - RIGHT
+export const load = async () => {
+	return {
+		userId: '123456789012345678901234567890', // String
+	};
+};
+```
+
+## Detecting Serialization Issues
+
+SvelteKit will throw an error if you try to return non-serializable
+data:
+
+```
+Error: Data returned from `load` while rendering / is not serializable:
+  - Cannot stringify arbitrary non-POJOs
+```
+
+## Testing Serialization
+
+```typescript
+const data = { user: new User() };
+
+try {
+	JSON.parse(JSON.stringify(data));
+	console.log('✅ Serializable');
+} catch (e) {
+	console.log('❌ Not serializable');
+}
+```
+
+## TypeScript Help
+
+Use `satisfies` to catch issues at compile time:
+
+```typescript
+import type { PageServerLoad } from './$types';
+
+export const load = (async () => {
+	return {
+		user: {
+			id: 1,
+			name: 'Alice',
+			createdAt: new Date(), // TypeScript allows this, but it's problematic
+		},
+	};
+}) satisfies PageServerLoad;
+```
+
+Better: Create a type that only allows primitives:
+
+```typescript
+type Serializable =
+	| string
+	| number
+	| boolean
+	| null
+	| { [key: string]: Serializable }
+	| Serializable[];
+
+export const load: PageServerLoad = async () => {
+	const data: Serializable = {
+		user: {
+			id: 1,
+			name: 'Alice',
+			createdAt: new Date().toISOString(), // Must be string
+		},
+	};
+
+	return data;
+};
+```
+
+## Quick Checklist
+
+Before returning from server load or form action:
+
+1. ✅ All values are string, number, boolean, null, array, or plain
+   object?
+2. ✅ No Date objects? (convert to `.toISOString()`)
+3. ✅ No undefined? (use null)
+4. ✅ No class instances? (convert to plain objects)
+5. ✅ No Map/Set? (convert to object/array)
+6. ✅ No functions?
+7. ✅ No BigInt? (convert to string)

.agents/skills/sveltekit-structure/README.md

@@ -0,0 +1,17 @@
+# Sveltekit Structure
+
+SvelteKit structure guidance. Use for routing, layouts, error
+handling, and SSR. Covers file naming (+page vs +layout vs +server),
+nested layouts, error boundaries, and hydration.
+
+## Structure
+
+- `SKILL.md` - Main skill instructions
+- `references/` - Detailed documentation loaded as needed
+- `scripts/` - Executable code for deterministic operations
+- `assets/` - Templates, images, or other resources
+
+## Usage
+
+This skill is automatically discovered by Claude when relevant to the
+task.

.agents/skills/sveltekit-structure/SKILL.md

@@ -0,0 +1,79 @@
+---
+name: sveltekit-structure
+# IMPORTANT: Keep description on ONE line for Claude Code compatibility
+# prettier-ignore
+description: SvelteKit structure guidance. Use for routing, layouts, error handling, SSR, or svelte:boundary. Covers file naming, nested layouts, error boundaries, pending UI, and hydration.
+---
+
+# SvelteKit Structure
+
+## Quick Start
+
+**File types:** `+page.svelte` (page) | `+layout.svelte` (wrapper) |
+`+error.svelte` (error boundary) | `+server.ts` (API endpoint)
+
+**Routes:** `src/routes/about/+page.svelte` → `/about` |
+`src/routes/posts/[id]/+page.svelte` → `/posts/123`
+
+**Layouts:** Apply to all child routes. `+layout.svelte` at any level
+wraps descendants.
+
+## Example
+
+```
+src/routes/
+├── +layout.svelte              # Root layout (all pages)
+├── +page.svelte                # Homepage /
+├── about/+page.svelte          # /about
+└── dashboard/
+    ├── +layout.svelte          # Dashboard layout (dashboard pages only)
+    ├── +page.svelte            # /dashboard
+    └── settings/+page.svelte   # /dashboard/settings
+```
+
+```svelte
+<!-- +layout.svelte -->
+<script>
+	let { children } = $props();
+</script>
+
+<nav><!-- Navigation --></nav>
+<main>{@render children()}</main>
+<footer><!-- Footer --></footer>
+```
+
+## Reference Files
+
+- [file-naming.md](references/file-naming.md) - File naming
+  conventions
+- [layout-patterns.md](references/layout-patterns.md) - Nested layouts
+- [error-handling.md](references/error-handling.md) - +error.svelte
+  placement
+- [svelte-boundary.md](references/svelte-boundary.md) -
+  Component-level error/pending
+- [ssr-hydration.md](references/ssr-hydration.md) - SSR and
+  browser-only code
+
+## Notes
+
+- Layouts: `{@render children()}` | Errors: +error.svelte _above_
+  failing route
+- Groups: `(name)` folders don't affect URL | Client-only: check
+  `browser`
+- **Last verified:** 2025-01-11
+
+<!--
+PROGRESSIVE DISCLOSURE GUIDELINES:
+- Keep this file ~50 lines total (max ~150 lines)
+- Use 1-2 code blocks only (recommend 1)
+- Keep description <200 chars for Level 1 efficiency
+- Move detailed docs to references/ for Level 3 loading
+- This is Level 2 - quick reference ONLY, not a manual
+
+LLM WORKFLOW (when editing this file):
+1. Write/edit SKILL.md
+2. Format (if formatter available)
+3. Run: claude-skills-cli validate <path>
+4. If multi-line description warning: run claude-skills-cli doctor <path>
+5. Validate again to confirm
+-->

.agents/skills/sveltekit-structure/references/error-handling.md

@@ -0,0 +1,274 @@
+# Error Handling
+
+## Error Boundary Placement
+
+**Key rule:** `+error.svelte` must be _above_ the failing route in the
+hierarchy.
+
+```
+src/routes/
+├── +error.svelte           # Catches errors in all routes below
+├── +page.svelte            # If this errors → uses +error.svelte above
+└── admin/
+    ├── +error.svelte       # Catches errors in admin routes
+    └── +page.svelte        # If this errors → uses admin/+error.svelte
+```
+
+**Wrong:**
+
+```
+src/routes/dashboard/
+├── +layout.svelte          # If this errors...
+└── +error.svelte           # This won't catch it (too low)
+```
+
+**Right:**
+
+```
+src/routes/
+├── +error.svelte           # Catches dashboard layout errors
+└── dashboard/
+    ├── +layout.svelte
+    └── +error.svelte       # Catches dashboard page errors
+```
+
+## Error Propagation
+
+Errors bubble up to the nearest `+error.svelte`:
+
+```
+src/routes/
+├── +error.svelte                    # Level 1 (root fallback)
+└── blog/
+    ├── +error.svelte                # Level 2 (blog fallback)
+    └── [slug]/
+        ├── +layout.server.ts        # Error here → blog/+error.svelte
+        ├── +page.server.ts          # Error here → blog/+error.svelte
+        └── +page.svelte             # Error here → blog/+error.svelte
+```
+
+**If no error boundary exists at that level, it goes to the parent.**
+
+## Basic Error Page
+
+```svelte
+<!-- +error.svelte -->
+<script>
+	import { page } from '$app/stores';
+</script>
+
+<h1>{$page.status}</h1><p>{$page.error.message}</p>
+```
+
+## Custom Error Data
+
+```typescript
+// +page.server.ts
+import { error } from '@sveltejs/kit';
+
+export const load = async ({ params }) => {
+	const post = await getPost(params.id);
+
+	if (!post) {
+		throw error(404, {
+			message: 'Post not found',
+			postId: params.id,
+		});
+	}
+
+	return { post };
+};
+```
+
+```svelte
+<!-- +error.svelte -->
+<script>
+	import { page } from '$app/stores';
+</script>
+
+<h1>{$page.status}</h1>
+<p>{$page.error.message}</p>
+
+{#if $page.error.postId}
+	<p>Could not find post with ID: {$page.error.postId}</p>
+{/if}
+```
+
+## Status Code Specific Errors
+
+```svelte
+<!-- +error.svelte -->
+<script>
+	import { page } from '$app/stores';
+</script>
+
+{#if $page.status === 404}
+	<h1>Page Not Found</h1>
+	<p>The page you're looking for doesn't exist.</p>
+	<a href="/">Go home</a>
+{:else if $page.status === 403}
+	<h1>Access Denied</h1>
+	<p>You don't have permission to view this page.</p>
+{:else if $page.status === 401}
+	<h1>Unauthorized</h1>
+	<p>Please log in to continue.</p>
+	<a href="/login">Login</a>
+{:else if $page.status >= 500}
+	<h1>Server Error</h1>
+	<p>Something went wrong on our end. Please try again later.</p>
+{:else}
+	<h1>Error {$page.status}</h1>
+	<p>{$page.error.message}</p>
+{/if}
+```
+
+## Common Status Codes
+
+- **400** - Bad Request (malformed request)
+- **401** - Unauthorized (not logged in)
+- **403** - Forbidden (logged in but no permission)
+- **404** - Not Found (resource doesn't exist)
+- **500** - Internal Server Error (unhandled exception)
+- **503** - Service Unavailable (server overloaded/down)
+
+## Error in Layout vs Page
+
+**Layout error:**
+
+```typescript
+// src/routes/dashboard/+layout.server.ts
+export const load = async ({ locals }) => {
+	if (!locals.user) {
+		throw error(401, 'Not logged in'); // Caught by +error.svelte ABOVE dashboard
+	}
+	return { user: locals.user };
+};
+```
+
+**Page error:**
+
+```typescript
+// src/routes/dashboard/settings/+page.server.ts
+export const load = async () => {
+	throw error(404, 'Settings not found'); // Caught by nearest +error.svelte
+};
+```
+
+## Expected Errors vs Unexpected Errors
+
+**Expected (use error()):**
+
+```typescript
+// User requests invalid resource
+if (!post) throw error(404, 'Post not found');
+
+// User lacks permission
+if (post.authorId !== user.id) throw error(403, 'Not your post');
+```
+
+**Unexpected (let it bubble):**
+
+```typescript
+// Unhandled exceptions (DB connection fails, etc.)
+// Will show generic 500 error
+const posts = await db.query.posts.findMany(); // Might throw
+```
+
+## Handling Errors in handleError Hook
+
+```typescript
+// src/hooks.server.ts
+import type { HandleServerError } from '@sveltejs/kit';
+
+export const handleError: HandleServerError = ({ error, event }) => {
+	// Log to error tracking service
+	console.error('Error:', error, 'Path:', event.url.pathname);
+
+	// Return user-friendly message (don't expose internals)
+	return {
+		message: 'An unexpected error occurred',
+		code: error?.code ?? 'UNKNOWN',
+	};
+};
+```
+
+## Error in Load vs Error in Component
+
+**Load function error (recommended):**
+
+```typescript
+// +page.server.ts
+export const load = async ({ params }) => {
+	const user = await getUser(params.id);
+	if (!user) throw error(404, 'User not found'); // Shows +error.svelte
+	return { user };
+};
+```
+
+**Component error (not ideal):**
+
+```svelte
+<!-- +page.svelte - Don't do this -->
+<script>
+	export let data;
+
+	// If data.user is undefined, component just shows nothing
+	// No error boundary triggered
+</script>
+
+<h1>{data.user.name}</h1> <!-- Might crash if user undefined -->
+```
+
+**Best practice:** Validate and throw errors in `load` functions, not
+components.
+
+## Fallback Error Handling
+
+Always have a root `+error.svelte`:
+
+```svelte
+<!-- src/routes/+error.svelte -->
+<script>
+	import { page } from '$app/stores';
+	import { dev } from '$app/environment';
+</script>
+
+<h1>Oops! Something went wrong</h1>
+
+{#if dev}
+	<!-- Show details in dev mode -->
+	<pre>{JSON.stringify($page.error, null, 2)}</pre>
+{:else}
+	<!-- Generic message in production -->
+	<p>We're sorry, but something unexpected happened.</p>
+{/if}
+
+<a href="/">Go home</a>
+```
+
+## Testing Error Boundaries
+
+```typescript
+// +page.server.ts
+export const load = async ({ url }) => {
+	// Test error page in dev
+	if (url.searchParams.has('test-error')) {
+		throw error(500, 'Test error');
+	}
+
+	return {};
+};
+```
+
+Visit `http://localhost:5173/page?test-error` to see error boundary.
+
+## Key Takeaways
+
+1. ✅ Place `+error.svelte` ABOVE failing routes
+2. ✅ Errors bubble up to nearest error boundary
+3. ✅ Always have a root `src/routes/+error.svelte`
+4. ✅ Throw errors in `load` functions, not components
+5. ✅ Use specific status codes (401, 403, 404, 500)
+6. ✅ Customize error pages per section (blog, admin, etc.)
+7. ✅ Use `handleError` hook for logging/monitoring
+8. ✅ Show detailed errors in dev, generic in production

.agents/skills/sveltekit-structure/references/file-naming.md

@@ -0,0 +1,69 @@
+# File Naming Conventions
+
+## Core Files
+
+| File                | Purpose               | Runs                  | Example                                       |
+| ------------------- | --------------------- | --------------------- | --------------------------------------------- |
+| `+page.svelte`      | Page component        | Client & Server (SSR) | `/routes/about/+page.svelte` → `/about`       |
+| `+page.ts`          | Universal load        | Client & Server       | Data for +page.svelte                         |
+| `+page.server.ts`   | Server load & actions | Server only           | DB queries, form actions                      |
+| `+layout.svelte`    | Layout wrapper        | Client & Server       | Wraps child routes                            |
+| `+layout.ts`        | Layout universal load | Client & Server       | Data for +layout.svelte                       |
+| `+layout.server.ts` | Layout server load    | Server only           | Auth, user data                               |
+| `+error.svelte`     | Error boundary        | Client & Server       | Shown when error thrown                       |
+| `+server.ts`        | API endpoint          | Server only           | `/routes/api/users/+server.ts` → `/api/users` |
+
+## Route Parameters
+
+| Pattern        | Matches        | Example                                                          |
+| -------------- | -------------- | ---------------------------------------------------------------- |
+| `[id]`         | Single param   | `/posts/[id]/+page.svelte` → `/posts/123`                        |
+| `[slug]`       | Single param   | `/blog/[slug]/+page.svelte` → `/blog/hello-world`                |
+| `[[optional]]` | Optional param | `/search/[[query]]/+page.svelte` → `/search` or `/search/svelte` |
+| `[...rest]`    | Rest params    | `/docs/[...path]/+page.svelte` → `/docs/a/b/c`                   |
+
+## Route Groups
+
+| Pattern       | Purpose                      | URL                                            |
+| ------------- | ---------------------------- | ---------------------------------------------- |
+| `(group)`     | Group routes (no URL impact) | `/(app)/dashboard/+page.svelte` → `/dashboard` |
+| `(marketing)` | Separate layouts             | Different layout for marketing pages           |
+
+## Special Files
+
+- `hooks.server.ts` - Server hooks (handle function, runs on every
+  request)
+- `hooks.client.ts` - Client hooks (runs in browser)
+- `app.html` - HTML template
+- `service-worker.ts` - Service worker
+- `params/*.ts` - Param validators
+
+## Common Patterns
+
+```
+src/routes/
+├── +layout.svelte              # Root layout
+├── +layout.ts                  # Root data
+├── +page.svelte                # Homepage
+├── +error.svelte               # Root error boundary
+│
+├── (app)/                      # App routes (grouped)
+│   ├── +layout.svelte          # App layout (auth required)
+│   ├── dashboard/+page.svelte  # /dashboard
+│   └── settings/+page.svelte   # /settings
+│
+├── (marketing)/                # Marketing routes (grouped)
+│   ├── +layout.svelte          # Marketing layout
+│   ├── about/+page.svelte      # /about
+│   └── pricing/+page.svelte    # /pricing
+│
+├── blog/
+│   ├── +page.svelte            # /blog (list)
+│   └── [slug]/
+│       ├── +page.svelte        # /blog/post-title
+│       └── +page.server.ts     # Load post data
+│
+└── api/
+    └── posts/
+        └── +server.ts          # API: GET/POST /api/posts
+```

.agents/skills/sveltekit-structure/references/layout-patterns.md

@@ -0,0 +1,387 @@
+# Layout Patterns
+
+## Basic Layout
+
+```svelte
+<!-- src/routes/+layout.svelte -->
+<script>
+	let { children } = $props();
+</script>
+
+<header>Header</header>
+<main>{@render children()}</main>
+<footer>Footer</footer>
+```
+
+**Key points:**
+
+- Must declare `children` in `$props()`
+- Use `{@render children()}` to render nested content
+- Root layout wraps ALL pages
+
+## Nested Layouts
+
+Layouts inherit from parent layouts:
+
+```
+src/routes/
+├── +layout.svelte          # Root layout (all pages)
+└── dashboard/
+    ├── +layout.svelte      # Dashboard layout (dashboard pages only)
+    └── +page.svelte        # Uses both layouts
+```
+
+**Result:** Root layout wraps dashboard layout wraps page.
+
+**Rendering order:**
+
+```
+Root +layout.svelte
+  └─ Dashboard +layout.svelte
+      └─ +page.svelte
+```
+
+### Example: Nested Layout Pattern
+
+```svelte
+<!-- src/routes/+layout.svelte -->
+<script>
+	let { children } = $props();
+</script>
+
+<div class="app">
+	<nav>Global Nav</nav>
+	{@render children()}
+</div>
+```
+
+```svelte
+<!-- src/routes/dashboard/+layout.svelte -->
+<script>
+	let { children } = $props();
+</script>
+
+<div class="dashboard">
+	<aside>Dashboard Sidebar</aside>
+	<main>{@render children()}</main>
+</div>
+```
+
+```svelte
+<!-- src/routes/dashboard/+page.svelte --><h1>Dashboard Home</h1>
+```
+
+**Rendered HTML structure:**
+
+```html
+<div class="app">
+	<nav>Global Nav</nav>
+	<div class="dashboard">
+		<aside>Dashboard Sidebar</aside>
+		<main>
+			<h1>Dashboard Home</h1>
+		</main>
+	</div>
+</div>
+```
+
+## Layout Groups
+
+Use `(groups)` to organize without affecting URLs:
+
+```
+src/routes/
+├── (marketing)/
+│   ├── +layout.svelte      # Marketing layout
+│   ├── about/+page.svelte  # /about (uses marketing layout)
+│   └── pricing/+page.svelte # /pricing (uses marketing layout)
+│
+└── (app)/
+    ├── +layout.svelte      # App layout
+    ├── dashboard/+page.svelte  # /dashboard (uses app layout)
+    └── settings/+page.svelte   # /settings (uses app layout)
+```
+
+**Key points:**
+
+- Parentheses make groups invisible in URLs
+- `/about` route, NOT `/(marketing)/about`
+- Different layouts for different sections
+- Useful for authentication boundaries
+
+### Example: Marketing vs App Layouts
+
+```svelte
+<!-- src/routes/(marketing)/+layout.svelte -->
+<script>
+	let { children } = $props();
+</script>
+
+<header class="marketing-header">
+	<nav>
+		<a href="/">Home</a>
+		<a href="/about">About</a>
+		<a href="/login">Login</a>
+	</nav>
+</header>
+
+{@render children()}
+
+<footer>© 2024 Company</footer>
+```
+
+```svelte
+<!-- src/routes/(app)/+layout.svelte -->
+<script>
+	let { children, data } = $props();
+</script>
+
+<header class="app-header">
+	<nav>
+		<a href="/dashboard">Dashboard</a>
+		<a href="/settings">Settings</a>
+		<span>Welcome, {data.user.name}</span>
+	</nav>
+</header>
+
+{@render children()}
+```
+
+## Reset Layout
+
+Use `@` in filename to break layout inheritance:
+
+**NOT RECOMMENDED** - This feature is deprecated in SvelteKit 2+.
+
+Instead, use layout groups to create separate hierarchies:
+
+```
+src/routes/
+├── +layout.svelte          # Root layout (for most pages)
+├── (app)/
+│   └── +layout.svelte      # App layout
+└── (public)/
+    └── +layout.svelte      # Public layout (completely separate)
+```
+
+## Layout with Data Loading
+
+```svelte
+<!-- src/routes/+layout.server.ts -->
+export const load = async ({ locals }) => {
+	// Available to all child routes
+	return {
+		user: locals.user,
+	};
+};
+```
+
+```svelte
+<!-- src/routes/+layout.svelte -->
+<script>
+	let { children, data } = $props();
+</script>
+
+<header>
+	{#if data.user}
+		<span>Welcome, {data.user.name}</span>
+	{:else}
+		<a href="/login">Login</a>
+	{/if}
+</header>
+
+{@render children()}
+```
+
+## Conditional Layout Content
+
+```svelte
+<!-- +layout.svelte -->
+<script>
+	import { page } from '$app/stores';
+	let { children } = $props();
+</script>
+
+{#if !$page.url.pathname.startsWith('/admin')}
+	<header>Public Header</header>
+{/if}
+
+{@render children()}
+
+{#if !$page.url.pathname.includes('/checkout')}
+	<footer>Footer</footer>
+{/if}
+```
+
+**Better approach:** Use layout groups instead of conditionals.
+
+## Protected Layouts
+
+```typescript
+// src/routes/(app)/+layout.server.ts
+import { redirect } from '@sveltejs/kit';
+
+export const load = async ({ locals }) => {
+	if (!locals.user) {
+		throw redirect(303, '/login');
+	}
+
+	return {
+		user: locals.user,
+	};
+};
+```
+
+All routes under `(app)` group now require authentication.
+
+## Sharing Layout State
+
+```svelte
+<!-- src/routes/+layout.svelte -->
+<script>
+	import { setContext } from 'svelte';
+	let { children, data } = $props();
+
+	// Share state with all descendant components
+	setContext('user', data.user);
+</script>
+
+{@render children()}
+```
+
+```svelte
+<!-- Any child component -->
+<script>
+	import { getContext } from 'svelte';
+	const user = getContext('user');
+</script>
+
+<p>Hello, {user.name}</p>
+```
+
+## Layout Slot Props (Snippets)
+
+```svelte
+<!-- src/routes/dashboard/+layout.svelte -->
+<script>
+	let { children, header } = $props();
+</script>
+
+<div class="dashboard">
+	<aside>Sidebar</aside>
+	<div class="content">
+		{#if header}
+			<header>{@render header()}</header>
+		{/if}
+		<main>{@render children()}</main>
+	</div>
+</div>
+```
+
+```svelte
+<!-- src/routes/dashboard/+page.svelte -->
+{#snippet header()}
+	<h1>Custom Dashboard Header</h1>
+{/snippet}
+
+<p>Dashboard content</p>
+```
+
+## Common Patterns
+
+### Pattern 1: Auth Boundary
+
+```
+src/routes/
+├── +layout.svelte           # Root (no auth)
+├── (public)/
+│   ├── +layout.svelte       # Public layout (landing pages)
+│   ├── +page.svelte         # /
+│   └── about/+page.svelte   # /about
+└── (protected)/
+    ├── +layout.server.ts    # Check auth, redirect if not logged in
+    ├── +layout.svelte       # Protected layout (app UI)
+    ├── dashboard/+page.svelte  # /dashboard
+    └── settings/+page.svelte   # /settings
+```
+
+### Pattern 2: Multi-tenant with Shared Root
+
+```
+src/routes/
+├── +layout.svelte           # Root layout (shared)
+├── admin/
+│   ├── +layout.svelte       # Admin layout
+│   └── users/+page.svelte   # /admin/users
+└── client/
+    ├── +layout.svelte       # Client layout
+    └── projects/+page.svelte # /client/projects
+```
+
+### Pattern 3: Progressive Enhancement
+
+```svelte
+<!-- src/routes/+layout.svelte -->
+<script>
+	import { page } from '$app/stores';
+	import { navigating } from '$app/stores';
+	let { children } = $props();
+</script>
+
+<div class="app">
+	{#if $navigating}
+		<div class="loading-bar"></div>
+	{/if}
+
+	{@render children()}
+</div>
+
+<style>
+	.loading-bar {
+		position: fixed;
+		top: 0;
+		left: 0;
+		width: 100%;
+		height: 3px;
+		background: blue;
+		animation: loading 1s ease-in-out;
+	}
+</style>
+```
+
+## Layout Best Practices
+
+1. ✅ Keep root layout minimal (shared across ALL pages)
+2. ✅ Use layout groups for separate sections
+3. ✅ Load shared data in layout's load function
+4. ✅ Use context for sharing state with descendants
+5. ✅ Avoid too many nested layouts (max 2-3 levels)
+6. ✅ Don't put auth logic in root layout (use groups)
+7. ✅ Remember: layouts share data DOWN, not UP
+8. ❌ Avoid conditionals in layouts (use groups instead)
+
+## Debugging Layouts
+
+```svelte
+<!-- src/routes/+layout.svelte -->
+<script>
+	import { page } from '$app/stores';
+	let { children } = $props();
+
+	$effect(() => {
+		console.log('Current route:', $page.url.pathname);
+		console.log('Layout data:', $page.data);
+	});
+</script>
+
+{@render children()}
+```
+
+## Key Takeaways
+
+- Layouts wrap all child routes
+- Nested layouts create hierarchy (root → section → page)
+- Groups `(name)` organize without affecting URLs
+- Load data in `+layout.server.ts` to share with children
+- Use context to share reactive state
+- Keep layouts simple and focused

.agents/skills/sveltekit-structure/references/ssr-hydration.md

@@ -0,0 +1,92 @@
+# SSR & Hydration
+
+## The Problem
+
+SvelteKit runs on server (SSR) then hydrates in browser. Code using
+browser APIs (`window`, `document`, `localStorage`) fails on server.
+
+## Solution: Check for Browser
+
+```typescript
+import { browser } from '$app/environment';
+
+// In load function
+export const load = async () => {
+	const theme = browser ? localStorage.getItem('theme') : 'light';
+	return { theme };
+};
+```
+
+```svelte
+<!-- In component -->
+<script>
+	import { browser } from '$app/environment';
+	import { onMount } from 'svelte';
+
+	let data = $state(null);
+
+	// Option 1: Use browser check
+	if (browser) {
+		data = localStorage.getItem('data');
+	}
+
+	// Option 2: Use onMount (only runs in browser)
+	onMount(() => {
+		data = localStorage.getItem('data');
+	});
+
+	// Option 3: Use $effect with browser check
+	$effect(() => {
+		if (browser) {
+			data = localStorage.getItem('data');
+		}
+	});
+</script>
+```
+
+## Common Mistakes
+
+### ❌ Using window Without Check
+
+```typescript
+// WRONG - fails on server
+export const load = async () => {
+	const width = window.innerWidth; // ERROR on server
+	return { width };
+};
+
+// RIGHT
+import { browser } from '$app/environment';
+
+export const load = async () => {
+	const width = browser ? window.innerWidth : 1024;
+	return { width };
+};
+```
+
+### ❌ Accessing DOM in Load
+
+```typescript
+// WRONG
+export const load = async () => {
+	const el = document.getElementById('root'); // ERROR on server
+};
+
+// RIGHT - Do DOM stuff in onMount
+export const load = async () => {
+	return {};
+};
+// Then in component:
+onMount(() => {
+	const el = document.getElementById('root');
+});
+```
+
+## Disable SSR (Not Recommended)
+
+```typescript
+// +page.ts
+export const ssr = false; // Disables SSR for this page
+```
+
+Only use when absolutely necessary (e.g., heavy Canvas/WebGL).

.agents/skills/sveltekit-structure/references/svelte-boundary.md

@@ -0,0 +1,150 @@
+# svelte:boundary Component
+
+> Available in Svelte 5.3+
+
+## Two Purposes
+
+1. **Error boundaries** - catch rendering errors
+2. **Pending UI** - show loading state while `await` resolves
+
+## Basic Error Boundary
+
+```svelte
+<svelte:boundary onerror={(e, reset) => console.error(e)}>
+	<RiskyComponent />
+
+	{#snippet failed(error, reset)}
+		<p>Error: {error.message}</p>
+		<button onclick={reset}>Try again</button>
+	{/snippet}
+</svelte:boundary>
+```
+
+## Pending UI (Loading States)
+
+> **⚠️ Known Bug:** `<svelte:boundary>` + `{@const await}` causes
+> infinite navigation loops during client-side page transitions when
+> pages share async queries. See
+> [sveltejs/svelte#17717](https://github.com/sveltejs/svelte/issues/17717).
+> Use `{#await}` blocks until this is fixed.
+
+With `experimental.async: true` (Svelte 5.36+), `{@const await}` is
+possible but **not safe for pages with shared queries or navigation**:
+
+```svelte
+<!-- ⚠️ Causes navigation loops - use {#await} instead -->
+<svelte:boundary>
+	{#snippet pending()}
+		<LoadingSpinner />
+	{/snippet}
+
+	{@const data = await loadData()}
+	<DataView {data} />
+</svelte:boundary>
+```
+
+**Safe alternative:**
+
+```svelte
+{#await loadData()}
+	<LoadingSpinner />
+{:then data}
+	<DataView {data} />
+{:catch error}
+	<p>Error: {error.message}</p>
+{/await}
+```
+
+## Combined Error + Pending
+
+Use `svelte:boundary` for **error catching only**, with `{#await}` for
+async data:
+
+```svelte
+<svelte:boundary onerror={logError}>
+	{#snippet failed(error, reset)}
+		<p>Failed to load user</p>
+		<button onclick={reset}>Retry</button>
+	{/snippet}
+
+	{#await fetchUser()}
+		<p>Loading user...</p>
+	{:then user}
+		<UserProfile {user} />
+	{:catch error}
+		<p>Error: {error.message}</p>
+	{/await}
+</svelte:boundary>
+```
+
+## What Gets Caught
+
+**Caught:**
+
+- Errors during rendering
+- Errors in `$effect`
+
+**NOT Caught:**
+
+- Event handler errors (`onclick`, etc.)
+- Errors after `setTimeout`
+- Async errors outside boundary's await
+
+## vs +error.svelte
+
+| Feature  | svelte:boundary         | +error.svelte |
+| -------- | ----------------------- | ------------- |
+| Scope    | Component subtree       | Route segment |
+| Reset    | Built-in reset function | Navigate away |
+| Pending  | Yes (pending snippet)   | No            |
+| Use case | Component-level         | Page-level    |
+
+## Error Tracking Integration
+
+```svelte
+<svelte:boundary
+	onerror={(error, reset) => {
+		// Send to Sentry, LogRocket, etc.
+		errorTracker.captureException(error);
+	}}
+>
+	<App />
+
+	{#snippet failed(error, reset)}
+		<ErrorFallback {error} {reset} />
+	{/snippet}
+</svelte:boundary>
+```
+
+## Nested Boundaries
+
+Inner boundary catches first:
+
+```svelte
+<svelte:boundary>
+	<!-- Outer fallback -->
+	{#snippet failed(e)}
+		<p>Outer caught: {e.message}</p>
+	{/snippet}
+
+	<svelte:boundary>
+		<!-- Inner fallback -->
+		{#snippet failed(e)}
+			<p>Inner caught: {e.message}</p>
+		{/snippet}
+
+		<ComponentThatMightFail />
+	</svelte:boundary>
+</svelte:boundary>
+```
+
+## Key Points
+
+- Use `svelte:boundary` for component-level error isolation
+- Use `+error.svelte` for route-level error pages
+- `pending` snippet shows only on **initial** load (not on refresh - no flicker)
+- `failed` snippet replaces content on error
+- `reset` function lets users retry
+- Errors in event handlers are NOT caught
+- Requires `experimental.async: true` in svelte.config.js for `{@const await}`
+- **⚠️ Bug:** `{@const await}` + navigation causes infinite loops ([#17717](https://github.com/sveltejs/svelte/issues/17717)) — use `{#await}` instead

.agents/skills/typescript-best-practices/SKILL.md

@@ -0,0 +1,270 @@
+---
+name: typescript-best-practices
+description: Provides TypeScript patterns for type-first development, making illegal states unrepresentable, exhaustive handling, and runtime validation. Must use when reading or writing TypeScript/JavaScript files.
+---
+
+# TypeScript Best Practices
+
+## Pair with React Best Practices
+
+When working with React components (`.tsx`, `.jsx` files or `@react` imports), always load `react-best-practices` alongside this skill. This skill covers TypeScript fundamentals; React-specific patterns (effects, hooks, refs, component design) are in the dedicated React skill.
+
+## Type-First Development
+
+Types define the contract before implementation. Follow this workflow:
+
+1. **Define the data model** - types, interfaces, and schemas first
+2. **Define function signatures** - input/output types before logic
+3. **Implement to satisfy types** - let the compiler guide completeness
+4. **Validate at boundaries** - runtime checks where data enters the system
+
+### Make Illegal States Unrepresentable
+
+Use the type system to prevent invalid states at compile time.
+
+**Discriminated unions for mutually exclusive states:**
+```ts
+// Good: only valid combinations possible
+type RequestState<T> =
+  | { status: 'idle' }
+  | { status: 'loading' }
+  | { status: 'success'; data: T }
+  | { status: 'error'; error: Error };
+
+// Bad: allows invalid combinations like { loading: true, error: Error }
+type RequestState<T> = {
+  loading: boolean;
+  data?: T;
+  error?: Error;
+};
+```
+
+**Branded types for domain primitives:**
+```ts
+type UserId = string & { readonly __brand: 'UserId' };
+type OrderId = string & { readonly __brand: 'OrderId' };
+
+// Compiler prevents passing OrderId where UserId expected
+function getUser(id: UserId): Promise<User> { /* ... */ }
+
+function createUserId(id: string): UserId {
+  return id as UserId;
+}
+```
+
+**Const assertions for literal unions:**
+```ts
+const ROLES = ['admin', 'user', 'guest'] as const;
+type Role = typeof ROLES[number]; // 'admin' | 'user' | 'guest'
+
+// Array and type stay in sync automatically
+function isValidRole(role: string): role is Role {
+  return ROLES.includes(role as Role);
+}
+```
+
+**Required vs optional fields - be explicit:**
+```ts
+// Creation: some fields required
+type CreateUser = {
+  email: string;
+  name: string;
+};
+
+// Update: all fields optional
+type UpdateUser = Partial<CreateUser>;
+
+// Database row: all fields present
+type User = CreateUser & {
+  id: UserId;
+  createdAt: Date;
+};
+```
+
+## Module Structure
+
+Prefer smaller, focused files: one component, hook, or utility per file. Split when a file handles multiple concerns or exceeds ~200 lines. Colocate tests with implementation (`foo.test.ts` alongside `foo.ts`). Group related files by feature rather than by type.
+
+## Functional Patterns
+
+- Prefer `const` over `let`; use `readonly` and `Readonly<T>` for immutable data.
+- Use `array.map/filter/reduce` over `for` loops; chain transformations in pipelines.
+- Write pure functions for business logic; isolate side effects in dedicated modules.
+- Avoid mutating function parameters; return new objects/arrays instead.
+
+## Instructions
+
+- Enable `strict` mode; model data with interfaces and types. Strong typing catches bugs at compile time.
+- Every code path returns a value or throws; use exhaustive `switch` with `never` checks in default. Unhandled cases become compile errors.
+- Propagate errors with context; catching requires re-throwing or returning a meaningful result. Hidden failures delay debugging.
+- Handle edge cases explicitly: empty arrays, null/undefined inputs, boundary values. Defensive checks prevent runtime surprises.
+- Use `await` for async calls; wrap external calls with contextual error messages. Unhandled rejections crash Node processes.
+- Add or update focused tests when changing logic; test behavior, not implementation details.
+
+## Examples
+
+Explicit failure for unimplemented logic:
+```ts
+export function buildWidget(widgetType: string): never {
+  throw new Error(`buildWidget not implemented for type: ${widgetType}`);
+}
+```
+
+Exhaustive switch with never check:
+```ts
+type Status = "active" | "inactive";
+
+export function processStatus(status: Status): string {
+  switch (status) {
+    case "active":
+      return "processing";
+    case "inactive":
+      return "skipped";
+    default: {
+      const _exhaustive: never = status;
+      throw new Error(`unhandled status: ${_exhaustive}`);
+    }
+  }
+}
+```
+
+Wrap external calls with context:
+```ts
+export async function fetchWidget(id: string): Promise<Widget> {
+  const response = await fetch(`/api/widgets/${id}`);
+  if (!response.ok) {
+    throw new Error(`fetch widget ${id} failed: ${response.status}`);
+  }
+  return response.json();
+}
+```
+
+Debug logging with namespaced logger:
+```ts
+import debug from "debug";
+
+const log = debug("myapp:widgets");
+
+export function createWidget(name: string): Widget {
+  log("creating widget: %s", name);
+  const widget = { id: crypto.randomUUID(), name };
+  log("created widget: %s", widget.id);
+  return widget;
+}
+```
+
+## Runtime Validation with Zod
+
+- Define schemas as single source of truth; infer TypeScript types with `z.infer<>`. Avoid duplicating types and schemas.
+- Use `safeParse` for user input where failure is expected; use `parse` at trust boundaries where invalid data is a bug.
+- Compose schemas with `.extend()`, `.pick()`, `.omit()`, `.merge()` for DRY definitions.
+- Add `.transform()` for data normalization at parse time (trim strings, parse dates).
+- Include descriptive error messages; use `.refine()` for custom validation logic.
+
+### Examples
+
+Schema as source of truth with type inference:
+```ts
+import { z } from "zod";
+
+const UserSchema = z.object({
+  id: z.string().uuid(),
+  email: z.string().email(),
+  name: z.string().min(1),
+  createdAt: z.string().transform((s) => new Date(s)),
+});
+
+type User = z.infer<typeof UserSchema>;
+```
+
+Return parse results to callers (never swallow errors):
+```ts
+import { z, SafeParseReturnType } from "zod";
+
+export function parseUserInput(raw: unknown): SafeParseReturnType<unknown, User> {
+  return UserSchema.safeParse(raw);
+}
+
+// Caller handles both success and error:
+const result = parseUserInput(formData);
+if (!result.success) {
+  setErrors(result.error.flatten().fieldErrors);
+  return;
+}
+await submitUser(result.data);
+```
+
+Strict parsing at trust boundaries:
+```ts
+export async function fetchUser(id: string): Promise<User> {
+  const response = await fetch(`/api/users/${id}`);
+  if (!response.ok) {
+    throw new Error(`fetch user ${id} failed: ${response.status}`);
+  }
+  const data = await response.json();
+  return UserSchema.parse(data); // throws if API contract violated
+}
+```
+
+Schema composition:
+```ts
+const CreateUserSchema = UserSchema.omit({ id: true, createdAt: true });
+const UpdateUserSchema = CreateUserSchema.partial();
+const UserWithPostsSchema = UserSchema.extend({
+  posts: z.array(PostSchema),
+});
+```
+
+## Configuration
+
+- Load config from environment variables at startup; validate with Zod before use. Invalid config should crash immediately.
+- Define a typed config object as single source of truth; avoid accessing `process.env` throughout the codebase.
+- Use sensible defaults for development; require explicit values for production secrets.
+
+### Examples
+
+Typed config with Zod validation:
+```ts
+import { z } from "zod";
+
+const ConfigSchema = z.object({
+  PORT: z.coerce.number().default(3000),
+  DATABASE_URL: z.string().url(),
+  API_KEY: z.string().min(1),
+  NODE_ENV: z.enum(["development", "production", "test"]).default("development"),
+});
+
+export const config = ConfigSchema.parse(process.env);
+```
+
+Access config values (not process.env directly):
+```ts
+import { config } from "./config";
+
+const server = app.listen(config.PORT);
+const db = connect(config.DATABASE_URL);
+```
+
+## Optional: type-fest
+
+For advanced type utilities beyond TypeScript builtins, consider [type-fest](https://github.com/sindresorhus/type-fest):
+
+- `Opaque<T, Token>` - cleaner branded types than manual `& { __brand }` pattern
+- `PartialDeep<T>` - recursive partial for nested objects
+- `ReadonlyDeep<T>` - recursive readonly for immutable data
+- `LiteralUnion<Literals, Fallback>` - literals with autocomplete + string fallback
+- `SetRequired<T, K>` / `SetOptional<T, K>` - targeted field modifications
+- `Simplify<T>` - flatten complex intersection types in IDE tooltips
+
+```ts
+import type { Opaque, PartialDeep, SetRequired } from 'type-fest';
+
+// Branded type (cleaner than manual approach)
+type UserId = Opaque<string, 'UserId'>;
+
+// Deep partial for patch operations
+type UserPatch = PartialDeep<User>;
+
+// Make specific fields required
+type UserWithEmail = SetRequired<Partial<User>, 'email'>;
+```