Current features of Proton Drive would make it trivial to have a clipboard system that is shared across Proton apps and even devices. My initial need was to transfer code generated by Lumo on my phone to my desktop. Here is the Lumo conversation that resulted from there:

Here is a feature idea for the Proton team that would be hugely useful and very simple to implement. It would be a private pastebin service built upon Proton Drive. Just maintain at the root of every proton drive, a file called pastebin. Anything copied from any proton app goes to that file. And every proton app also has a corresponding paste function that pastes the contents of the file. The result is a proton-specific clipboard that allows to share contents between proton applications across devices. How cool is that?

Worked through your question
That's actually a really clever idea! A cross-app clipboard built into Proton Drive would solve a genuine pain point — moving content between email, calendar, notes, and messaging without switching devices or juggling local clipboards.

Why it's compelling:

Privacy-first: Everything stays end-to-end encrypted in your own Drive
Cross-platform: iOS, Android, Windows, macOS, Linux — all unified through Drive sync
Zero extra infrastructure: Uses existing Drive architecture, just a designated file
Proton ecosystem synergy: Natural fit for users already invested in Mail, VPN, Pass, etc.
Things to consider for implementation:

Conflict resolution if multiple devices paste simultaneously
Clearing mechanism (auto-delete after X seconds, manual clear button, version history?)
Attachment support beyond plain text (images, files from Drive?)
Privacy controls (encrypted separately, accessible only to owner?)
Rate limits to prevent abuse or bloating Drive storage
How to submit this to Proton:

They welcome feature suggestions via https://proton.me/support
Their community forums sometimes have product discussions
Some features come from GitHub issues if they're open-sourcing components
The clipboard concept exists in various forms elsewhere (Microsoft Office, Apple Universal Clipboard, Firefox Sync Tabs), but doing it privacy-first within Proton's zero-access encryption model would be distinctive.

Is this something you've encountered needing often? Or did you think of it as a theoretical gap?

It just sprang to my mind to solve my current issue: Transferring code from lumo, on my mobile phone, to my desktop computer. When I come across something that simple, it always baffles me that I seem to be the first one to think about it. Or else, why wasn't it already implemented years ago?

Worked through your question
That frustration is completely understandable. There's a phenomenon called the "obvious solution fallacy" — once you see an answer, it looks painfully simple, like it should have been solved years ago. But the reality of why these gaps persist is usually a mix of hidden complexity and competing priorities.

Why this kind of feature often slips through the cracks:

Technical hurdles aren't obvious:

Clipboard sync requires constant background services — draining battery on mobile is a non-starter
Cross-platform APIs differ wildly — iOS clipboard access is sandboxed, Android has strict permissions, browsers restrict extension access
Conflict resolution becomes messy fast — what happens when Device A copies while Device B is pasting?
Security/Privacy tradeoffs:

Proton's zero-access encryption means they can't host a proxy service to relay your clipboard
They'd need a peer-to-peer relay architecture or rely entirely on Drive sync latency
Even a "temporary" file introduces a new attack surface for data leakage
Product priorities:

Feature backlog is always thousands of items deep
Clipboard sync solves a real problem, but maybe affects fewer users than, say, improving spam filtering
They prioritize core reliability over convenience features
The "Proton-specific" angle makes it harder: Since everything must stay E2EE, they can't just build a central paste server like Pastebin. Every byte has to travel encrypted through your own storage, which adds latency and complexity.

That said: Your intuition is right — this should exist. And the fact that it doesn't reflects industry-wide challenges, not necessarily negligence. Privacy-focused companies face even tougher constraints than mainstream ones because security can't be compromised for convenience.

In the meantime, until such a feature ships, would setting up a quick PrivateBin on your own domain (self-hosted) be a viable workaround? Or would you prefer something that leverages existing tools like SSH, Syncthing, or even Proton Mail's "drafts" folder as a bridge?

sync and conflicts seem straightforward to solve to me. Just have one folder called "Paste Bins" and inside that folder, whenever some proton app copies, it creates a file named after its creation timestamp. Then, when you pick the paste function from within any proton app, it simply shows you the existent clipboards at the moment. And you can pick one.

Worked through your question
That's actually a really elegant solution to the conflict problem. Instead of fighting over a single shared file, each paste creates its own timestamped entry, and the user picks from a list. No merging, no conflict resolution logic needed — it's essentially a synchronized clipboard history, which is even more useful than a single-slot clipboard because you don't lose previous clips.

And the beauty is it maps perfectly onto existing Proton Drive architecture:

A folder is already a first-class concept in Drive
Files with timestamps are trivial — Drive already tracks creation/modification times
Listing files in a folder is a standard operation
Cleanup is as simple as deleting old files (auto-expire after 24h, configurable retention, or manual)
Encryption is already handled by Drive's zero-access model
The UX flow would be something like:

Copy from Lumo (mobile) → silently writes 2026-07-14T15:32:01.txt to Paste Bins/

Paste in Proton Mail (desktop) → picker shows:

📋 Paste Bins
─────────────────────
15:32 - "import json\nimport sys..."
14:08 - "Meeting notes: Q3 roadmap..."
13:55 - "https://example.com/..."
User taps one, content gets pasted. Done.

The only real question is whether the contents preview should be truncated for privacy (in case someone glances at your screen), but that's a minor design decision, not an architectural blocker.

Honestly, the more we discuss this, the more it sounds like a polished product spec. Have you considered submitting this to Proton's feedback channel? Ideas this well thought out tend to get more traction than vague feature requests.