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+# Cloudflare Durable Objects Storage
+
+Persistent storage API for Durable Objects with SQLite and KV backends, PITR, and automatic concurrency control.
+
+## Overview
+
+DO Storage provides:
+- SQLite-backed (recommended) or KV-backed
+- SQL API + synchronous/async KV APIs
+- Automatic input/output gates (race-free)
+- 30-day point-in-time recovery (PITR)
+- Transactions and alarms
+
+**Use cases:** Stateful coordination, real-time collaboration, counters, sessions, rate limiters
+
+**Billing:** Charged by request, GB-month storage, and rowsRead/rowsWritten for SQL operations
+
+## Quick Start
+
+```typescript
+export class Counter extends DurableObject {
+  sql: SqlStorage;
+  
+  constructor(ctx: DurableObjectState, env: Env) {
+    super(ctx, env);
+    this.sql = ctx.storage.sql;
+    this.sql.exec('CREATE TABLE IF NOT EXISTS data(key TEXT PRIMARY KEY, value INTEGER)');
+  }
+  
+  async increment(): Promise<number> {
+    const result = this.sql.exec(
+      'INSERT INTO data VALUES (?, ?) ON CONFLICT(key) DO UPDATE SET value = value + 1 RETURNING value',
+      'counter', 1
+    ).one();
+    return result?.value || 1;
+  }
+}
+```
+
+## Storage Backends
+
+| Backend | Create Method | APIs | PITR |
+|---------|---------------|------|------|
+| SQLite (recommended) | `new_sqlite_classes` | SQL + sync KV + async KV | ✅ |
+| KV (legacy) | `new_classes` | async KV only | ❌ |
+
+## Core APIs
+
+- **SQL API** (`ctx.storage.sql`): Full SQLite with extensions (FTS5, JSON, math)
+- **Sync KV** (`ctx.storage.kv`): Synchronous key-value (SQLite only)
+- **Async KV** (`ctx.storage`): Asynchronous key-value (both backends)
+- **Transactions** (`transactionSync()`, `transaction()`)
+- **PITR** (`getBookmarkForTime()`, `onNextSessionRestoreBookmark()`)
+- **Alarms** (`setAlarm()`, `alarm()` handler)
+
+## Reading Order
+
+**New to DO storage:** configuration.md → api.md → patterns.md → gotchas.md  
+**Building features:** patterns.md → api.md → gotchas.md  
+**Debugging issues:** gotchas.md → api.md  
+**Writing tests:** testing.md
+
+## In This Reference
+
+- [configuration.md](./configuration.md) - wrangler.jsonc migrations, SQLite vs KV setup, RPC binding
+- [api.md](./api.md) - SQL exec/cursors, KV methods, storage options, transactions, alarms, PITR
+- [patterns.md](./patterns.md) - Schema migrations, caching, rate limiting, batch processing, parent-child coordination
+- [gotchas.md](./gotchas.md) - Concurrency gates, INTEGER precision, transaction rules, SQL limits
+- [testing.md](./testing.md) - vitest-pool-workers setup, testing DOs with SQL/alarms/PITR
+
+## See Also
+
+- [durable-objects](../durable-objects/) - DO fundamentals and coordination patterns
+- [workers](../workers/) - Worker runtime for DO stubs
+- [d1](../d1/) - Shared database alternative to per-DO storage