Upload Malware Scanning
Quarantine uploaded files until they are known safe.
What it adds
A quarantine lifecycle for uploads: every new file is unreachable until scanned, with defined handling for scanner failures and infected results.
What your agent is told to do
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What your agent is told to do
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Give every upload an explicit scan state — pending, clean, infected, or error — and default it to pending the moment the bytes land.
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Make pending and infected files unreachable from every access path in the app, including admin views, previews, thumbnails, and any signed URL. A quarantine with one exception is not a quarantine.
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Scan asynchronously and update the state; do not block the upload request on the scanner.
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Decide and document what an infected file does: delete immediately, or retain for a fixed period for investigation. Both are defensible; an undefined policy is not.
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Tell the user their file was rejected in plain language. Do NOT surface the signature name, the scanner's raw output, or any internal file path — that hands an attacker a feedback loop for tuning their payload.
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Signed-URL issuance and download authorization are owned by Secure File Downloads. Extend that feature to consult scan state rather than building a parallel delivery path here.
Edge cases it handles
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Edge cases it handles
7- A scanner timeout or outage must fail closed — the file stays pending and inaccessible, and the backlog is retried and alerted on.
- Files larger than the scanner's limit need an explicit decision, not a silent pass.
- Archives can hide payloads several layers deep, and zip bombs expand catastrophically. Cap recursion depth and expansion ratio.
- A file already marked clean can become infected as signatures update. Support re-scanning existing storage.
- False positives need a human review path, or you will permanently delete a customer's legitimate file.
- A URL signed while a file was clean must stop working the moment it is marked infected.
- Uploads that never complete scanning must not accumulate as permanent pending clutter — expire them.
Definition of done
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Definition of done
8- Every uploaded file has a scan state and starts as pending.
- Pending and infected files return no bytes from any route, signed or otherwise.
- Scanner outages and timeouts leave files inaccessible rather than passing them through.
- The infected-file retention or deletion policy is written down and implemented.
- User-facing rejection messages contain no signature names or internal paths.
- A previously clean file can be re-scanned and revoked.
- 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.