durable-objects

durable-objects is a skill for Claude Code, Codex from kevyder/banrepco_mcp. It costs 76 tokens per session (1,361 once invoked), scanned A, a copy of durable-objects, MPL-2.0.

A guide for building Cloudflare Durable Objects, which are server-side components that keep state and coordinate activity for a particular object or group. They can support features such as shared storage, timers, and live WebSocket connections.

In plain words
What is it for?
Use it to build chat rooms, multiplayer games, booking systems, RPC methods, alarms, WebSocket handlers, storage, configuration, and Vitest tests.
Why use it?
It provides the project-specific guidance needed when several users or processes must work with the same changing state at Cloudflare's edge locations.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/kevyder/banrepco_mcp/durable-objects
Any agent
npx skills add kevyder/banrepco_mcp --skill durable-objects
Clone the repo
git clone --depth 1 https://github.com/kevyder/banrepco_mcp

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for durable-objects

README.md
[![agentmods](https://agentmods.dev/badge/skills/kevyder/banrepco_mcp/durable-objects.svg)](https://agentmods.dev/skills/kevyder/banrepco_mcp/durable-objects)
Your own site
<a href="https://agentmods.dev/skills/kevyder/banrepco_mcp/durable-objects"><img src="https://agentmods.dev/badge/skills/kevyder/banrepco_mcp/durable-objects.svg" alt="Measured on agentmods" height="20"></a>
Per session 76 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,361 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin 100% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00076 $0.01361
Opus 5 $0.00038 $0.00681
Sonnet 5 $0.00015 $0.00272
Haiku 4.5 $0.00008 $0.00136

Measured 4d ago against content hash cd6797cb18f3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

durable-objects scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

async fetch(request: Request, env: Env): Promise<Response> {
Origin

This is a copy

100% identical to durable-objects — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/durable-objects/SKILL.md · 187 lines

How it starts

The opening of the file, as written. The whole thing — 187 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Durable Objects

Build stateful, coordinated applications on Cloudflare's edge using Durable Objects.

Retrieval Sources

Your knowledge of Durable Objects APIs and configuration may be outdated. Prefer retrieval over pre-training for any Durable Objects task.

Resource URL
Docs https://developers.cloudflare.com/durable-objects/
API Reference https://developers.cloudflare.com/durable-objects/api/
Best Practices https://developers.cloudflare.com/durable-objects/best-practices/
Examples https://developers.cloudflare.com/durable-objects/examples/

Fetch the relevant doc page when implementing features.

When to Use

  • Creating new Durable Object classes for stateful coordination
  • Implementing RPC methods, alarms, or WebSocket handlers
  • Reviewing existing DO code for best practices
  • Configuring wrangler.jsonc/toml for DO bindings and migrations
  • Writing tests with @cloudflare/vitest-pool-workers
  • Designing sharding strategies and parent-child relationships

Reference Documentation

  • ./references/rules.md - Core rules, storage, concurrency, RPC, alarms
  • ./references/testing.md - Vitest setup, unit/integration tests, alarm testing
  • ./references/workers.md - Workers handlers, types, wrangler config, observability

Search: blockConcurrencyWhile, idFromName, getByName, setAlarm, sql.exec

Core Principles

Use Durable Objects For

Need Example
Coordination Chat rooms, multiplayer games, collaborative docs
Strong consistency Inventory, booking systems, turn-based games
Per-entity storage Multi-tenant SaaS, per-user data
Persistent connections WebSockets, real-time notifications
Scheduled work per entity Subscription renewals, game timeouts

Do NOT Use For

  • Stateless request handling (use plain Workers)
  • Maximum global distribution needs
  • High fan-out independent requests

Quick Reference

Wrangler Configuration

Read the full file on GitHub · 187 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 187 lines · 76 tokens per session scan A cd6797cb18f3

Subscribe to this mod's changes

durable-objects is a skill published in the GitHub repository kevyder/banrepco_mcp (9 stars, last pushed 23d ago), licensed MPL-2.0. It adds 76 tokens to every session and 1,361 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 100% identical to durable-objects, differing in 0 lines, and is treated as a copy.

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