--- title: "Cloudflare Durable Objects: review, setup & limitations · Undominated.ai" canonical: https://undominated.ai/skills/cloudflare-durable-objects/ description: "Designs per-entity state and coordination with explicit persistence, concurrency and runtime-test guidance." --- # Cloudflare Durable Objects: review, setup & limitations · Undominated.ai > Designs per-entity state and coordination with explicit persistence, concurrency and runtime-test guidance. [← Explore all skills](/skills/) CLOUD DEVELOPMENT / Cloudflare # Cloudflare Durable Objects Designs per-entity state and coordination with explicit persistence, concurrency and runtime-test guidance. See setup guidance ↓Original source ↗ SOURCE REVIEW Reviewed 2026-09-21 Evidence 7 linked sources Publisher Cloudflare Licence Apache-2.0 ↗ Revision b052c32bab7d Read what was—and wasn’t—checked ↓ “Build, debug, or review Cloudflare Durable Objects code for persistent state and coordination.” Cloudflare · upstream description ↗ Our analysis follows below. 01 / THE REASONING ## Why this made the selection. - Defines where Durable Objects fit and where stateless Workers or independent requests fit better. - The testing reference distinguishes repeat calls from actual persistence recovery and asks for independent object identities. ### A good fit for - Designing a chat room, booking coordinator or per-tenant state object - Reviewing persistence, alarms and concurrency in an existing Durable Object ### Weigh up before choosing - A single coordination object can become a bottleneck; object boundaries must fit the workload. - The runtime and testing integration are Cloudflare-specific and version-sensitive. - Repeated successful RPC calls do not by themselves prove recovery after eviction or restart. 02 / THE REVIEW RECORD ## What we actually inspected. Source review has boundaries. A clear record is more useful than a “safe” badge. ### Material inspected - skills/durable-objects/SKILL.md - skills/durable-objects/references/rules.md - skills/durable-objects/references/testing.md - LICENSE ### Our findings - The rules require persisting important state before relying on memory and warn against holding initialization locks over external I/O. - The guide explains that setting a new alarm replaces the previous scheduled alarm for that object. - The testing reference requires checking installed integration/isolation behavior before changing an existing suite. ### Not established by this review - Source inspection only; no skill installation or workflow execution was performed. The review applies to the material and revision named here. A newer upstream release can change its behavior. 03 / PUT IT TO WORK ## Add a skill to your workflow. Upstream setup instructions ↗ DOCUMENTED COMMAND npx skills add https://github.com/cloudflare/skills/tree/b052c32bab7dd493513260228a36c88294f343f1/skills/durable-objects Copy command ↗ Copying does not execute this command. It may retrieve a newer version than the reviewed source. - Install the complete skill directory with its references and helpers; a copied SKILL.md alone may be incomplete. - Choose the intended agent and project scope in the installer, then review its permissions before using the skill. ### Before you start - Node.js/npm for this installer - An agent that supports the Agent Skills format - Bindings, migrations and a matching configured runtime - A Cloudflare account for deployed resource testing ### Compatibility Cloudflare Workers Durable Objects · Cloudflare Vitest integration for runtime tests ### Read and edit persistent-state code and configuration - Read and edit persistent-state code and configuration - Run local/runtime tests - Deployment and storage changes need appropriate cloud authority ### Cost model The Apache-licensed skill is separate from Cloudflare compute, storage and agent-service usage. 04 / FOLLOW THE EVIDENCE ## The source trail. Our notes are separate from the original resource. Check upstream before adopting a new version. - Skill definition at reviewed revision ↗ Checked 2026-09-21 https://github.com/cloudflare/skills/blob/b052c32bab7dd493513260228a36c88294f343f1/skills/durable-objects/SKILL.md Supports: summary, upstreamDescription, whySelected, bestFor, limitations, review, compatibility, access - Reviewed reference or helper: references/rules.md ↗ Checked 2026-09-21 https://github.com/cloudflare/skills/blob/b052c32bab7dd493513260228a36c88294f343f1/skills/durable-objects/references/rules.md Supports: review, limitations, access - Reviewed reference or helper: references/testing.md ↗ Checked 2026-09-21 https://github.com/cloudflare/skills/blob/b052c32bab7dd493513260228a36c88294f343f1/skills/durable-objects/references/testing.md Supports: review, limitations, access - Upstream license or licensing declaration ↗ Checked 2026-09-21 https://github.com/cloudflare/skills/blob/b052c32bab7dd493513260228a36c88294f343f1/LICENSE Supports: license - Publisher installation and project documentation ↗ Checked 2026-09-21 https://github.com/cloudflare/skills/blob/b052c32bab7dd493513260228a36c88294f343f1/README.md Supports: install, compatibility, access - Skills installer source formats and selective installation ↗ Checked 2026-09-21 https://github.com/vercel-labs/skills/blob/7407f3893ad4dceab546ac002c3ef806e4000c73/README.md Supports: install - Installer implementation: full commit SHA fallback ↗ Checked 2026-09-21 https://github.com/vercel-labs/skills/blob/7407f3893ad4dceab546ac002c3ef806e4000c73/src/git.ts Supports: install KEEP COMPARING ## Other approaches to consider. Related by category or shared topics. These are alternatives to inspect, not a measured quality order. [### Cloudflare Workers Best Practices ↗ Reviews Workers code against its configured runtime, focusing on request lifetime, state isolation, streaming and binding contracts.](/skills/cloudflare-workers-best-practices/)[### Cloudflare Agents SDK ↗ Guides stateful Cloudflare agent applications through current SDK documentation, persistence, scheduling and approval-aware tool flows.](/skills/cloudflare-agents-sdk/)[### Cloudflare Wrangler Workflow ↗ Runs Workers configuration and deployment work against the project’s installed Wrangler version and an explicitly identified target.](/skills/cloudflare-wrangler/) [AI Tools ↗](/tools/)[Skills ↗](/skills/)[Agents ↗](/agents/)[MCP Servers ↗](/mcp-servers/)