Offline Action Queue
Let people keep working through a dropped connection and sync it safely later.
What it adds
A durable queue that captures writes made while the app is offline and replays them against the server on reconnect.
What your agent is told to do
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What your agent is told to do
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Choose a small, explicit set of actions that are safe to queue. Build on the app's existing service worker and storage if it already has one rather than standing up a second offline layer.
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Persist queued actions durably so a reload or crash does not lose them, and record enough context to replay each one exactly.
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Give every queued action a client-generated idempotency key and have the server reject a repeat of the same key, so a retried request cannot write twice.
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Replay in the order the user performed the actions, and halt the dependent chain when one action fails rather than applying later actions against a state that never existed.
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Show the user what is queued, what synced, and what failed, with a way to retry or discard individual items.
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Do NOT queue anything the server might reject for authorization or business reasons without a plan for the rejection. A silently dropped write is worse than a write that never happened, because the user believes it landed.
Edge cases it handles
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Edge cases it handles
7- Do not store credentials, tokens, or sensitive field values in offline storage — it is readable on a shared or stolen device.
- A session that expires while offline must prompt for re-authentication before replay, not fail every queued item.
- Permissions can change while offline; a queued edit to a record the user no longer owns must surface as a conflict, not a crash.
- If the record changed server-side since the action was queued, present the conflict with both versions instead of blindly overwriting.
- A queue that fails permanently must be drainable: cap retries, mark items dead, and let the user export or discard them.
- Cap the queue size and the age of entries. Replaying a two-week-old action is usually wrong.
- Creating an item offline and then editing it requires the temporary local id to be remapped to the server id during replay.
Definition of done
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Definition of done
9- Queued actions survive reload and browser restart.
- Every replayed request carries an idempotency key and duplicates are rejected server-side.
- Replay preserves user ordering and stops a chain when a dependency fails.
- Expired sessions, permission changes, and validation failures each produce a specific, visible outcome.
- The user can see the queue and retry or discard individual failed items.
- No credentials or sensitive values are written to offline storage.
- The queue always reaches a terminal state — it cannot retry forever.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Password Generator
Password Generator
Offer a strong password in one click wherever someone sets or changes credentials.
What it does
A generate control on password fields that produces a strong value, shows it, and hands it to the user safely.
How it works
- 1 Add the control to every place a password is set: sign-up, password change, password reset completion, and any admin screen that provisions credentials for someone else.
- 2 Generate the value in the browser using the platform's cryptographic random source. The value must never be produced on the server or sent anywhere.
- 3 Reveal the generated password by default so the user can record it, and offer a regenerate control beside it. A hidden generated password that the user cannot see is a password they will immediately reset.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/password-generator
Idempotent Form Submission
Idempotent Form Submission
Make one submit mean one result, even when the network retries.
What it does
Idempotency keys on high-impact writes so a double-click, a retry, or a refresh cannot create the same record twice.
How it works
- 1 Find the writes where a duplicate is expensive — payments, orders, invitations, provisioning, anything that sends money or email.
- 2 Generate an idempotency key when the form is rendered, send it with the submission, and persist it server-side alongside the result of the first successful attempt.
- 3 When the same key arrives again, return the stored result instead of doing the work a second time. When the same key arrives with a different payload, reject it — that is a client bug, not a retry.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/idempotent-form-submission
Client Version Compatibility
Client Version Compatibility
Handle the tab that has been open since two deploys ago.
What it does
The server tells the client which build it expects, and the client responds — quietly for an optional update, insistently when the old code can no longer talk to the API.
How it works
- 1 Stamp every build with a version identifier and return it on API responses, either in a header or a small metadata endpoint. The client compares it against the version it was built as.
- 2 Separate two cases and treat them differently. A newer build being available is an optional update — offer it and let the user finish what they are doing. An API contract the running client cannot satisfy is a hard incompatibility and must block further writes.
- 3 For an optional update, show an unobtrusive, dismissible prompt and apply the new version at the next natural navigation. Do not interrupt.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/client-version-compatibility
How it works
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Copy the link
Grab the Markdown instruction URL for this feature.
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Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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It inspects, then implements
Your agent reads your existing app first, then adds the feature to fit it.
Works with your stack
These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.
Need it tighter than that? Customize the feature and tell it exactly what you're running.