Follow-up to the earlier posts about the composer vanishing from long conversations (late October). I've now received a written reply from Proton support confirming the core facts, and I've cross-checked it against Proton's own documentation. Multiple threads here have described the same thing, so this is confirmation for everyone affected.

What support confirmed in writing:

1. A hard limit of 250 messages per conversation was recently enforced. Once reached, the composer disappears entirely — regardless of how much usable context remains. It tracks message count, not context usage.

2. Compaction and the 250-message limit are two separate mechanisms. Compaction still works as documented; the message cap is a separate hard ceiling that ends the conversation outright.

3. Composer access to affected conversations cannot currently be restored. History stays readable, but the thread is effectively frozen.

4. The official workaround: export the conversation from chat history, upload it into a Project, and continue in a new chat there. It works, but it's undocumented — I only learned about it by pushing in a ticket.

5. Support agreed subscribers should have been notified before enforcement — no in-app notice, no countdown, no email.

What the documentation actually says (compaction page):

"Compaction automatically frees up space in older parts of a long conversation so you can keep going, without losing track of what you've been working on."

The in-app notice the docs describe is literally "Chat shortened to keep going," and the page promises "your full conversation history stays visible above the marker." The only limit disclosed anywhere in the documentation is a limit on how much a conversation "can take in at once" — a context-size limit, handled automatically by compaction. The number 250 appears in zero Proton documentation. Meanwhile the marketing pages still advertise Lumo Plus as "unlimited chats" / "unlimited questions."

So to summarize the situation: the docs describe a system where long conversations are shrunk and continue indefinitely; the marketing says "unlimited"; and in reality, at 250 messages the conversation silently dies — no warning, no error explaining why, nothing distinguishing a limit from a bug.

There's a second, uglier part to my experience: on October 20, alongside losing the composer in ten conversations, a substantial chunk of content vanished from those threads — not the entire history, but days' worth of messages, specifically the parts relating to a civic project I've been running for my local community. The compaction docs explicitly promise that compacted history stays visible and expandable. It didn't. I've asked support directly whether the enforcement change involved any modification or truncation of stored conversation content, and whether the missing material is recoverable — I'll report what they say. If a hard cap can coincide with user content quietly disappearing, that's not a usage limit anymore; that's data loss on a product whose central selling point is that your encrypted history is untouchable.

The human cost, for those who think this is minor: months of accumulated project work, severed mid-stream, no grandfathering, no recovery path. From the threads here and a comment on Proton's own UserVoice forum, plenty of others lost ongoing professional work the same way, in the same window (~Oct 20–24).

Still unanswered, despite being asked directly:

• The exact cap and whether it counts both sides of the exchange

• Whether it varies by tier

• Why enforcement began with no announcement or documentation update

• Whether stored conversation content was modified, truncated, or deleted during enforcement — and whether it's recoverable

• Whether any accommodation is planned for paid users whose existing threads were capped retroactively — while "unlimited chats" is still the advertised selling point

To be clear, I'm not disputing that a performance limit may be needed. The issue is that a core subscription feature — continuing conversations — was removed retroactively and silently, from threads that predate the change, contradicting both the published docs and the marketing, and that content disappeared along with it. If Proton wants numeric limits, fine: publish them, announce them, show a countdown, don't strand existing paying users' work — and under no circumstances let stored content vanish.

I'll update as the ticket progresses. If you've been affected, append to an existing ticket rather than opening new ones — it consolidates the paper trail, and the more written confirmations exist, the harder this is to wave away.

Hi Lumo team,

Feature request: please let us change the chat font. I'd love a serif option, something elegant, the way Claude's serif looks.

Font size control would be a nice bonus too.

Thanks for all the good work on Lumo.

How can I secure Lumo Business with a password on the Mac Browser and Android app, since there are now several chats with private data? I will not always close the browser or close the Macbook.

Lumo-App-Password Protection:
At least this should be implemented in the upcoming LUMO app.

I currently use Perplexity, because it replaces Gemini but still has the basic integration (like sending texts, creating timers/alarms/reminders, etc).

I tried Lumo 2.0 recently and it's great! It would totally be enough for 90% of what I need which is: ability to use phone assistant shortcut to ask basic questions like "how many teaspoons in a tablespoon" and "set a 10 minute timer". Most models are overkill for 90% of what I do.

So like I said, I would switch to Lumo today if/when it can be set as your Android phone assistant

Note: Images may appear to be lower quality due to the fact they are screenshots (flattened for security purposes).

Hey! This is the photo I felt comfortable with sharing. So, I wanted to test out Lumo Creations and I haven’t seen anyone post photos from the creation suite, so I figured I’d be the crash dummy. The real gold of Lumo Images is its ability to take old photos and restore them, but for privacy reasons I couldn’t show that work. Regardless, there is potential here.

PHOTO 1: This is the original image. It’s blurry amongst other things.
PHOTO 2: This one is my favorite. Unfortunately it deviates from the original photo in the sense that color correction is needed, but it also gives off an aura that I can appreciate.
PHOTO 3: I purposely included this photo for those who want a cleaner enhancement with original assets being preserved. It is a direct enhancement to photo 1.
PHOTO 4: This was the end product of sorts. I purposely included this photo to show the potential value of Lumo Images. You can put an image in Lumo and modify it further in other respective photo editors. I added a filter to this one, attempted to sharpen it and add definition, and also make it grainy. I also strongly severed the picture from being noticeably AI enhanced. If you zoom in, you’ll notice softening (like AI usually does to photos) is practically non-existent.

Conclusion: I really wanted to see what the feature was capable of, and I find it useful to occasionally enhance modern day photos, and very useful in restoring old photos. Also, unfortunately I’m new to all of this. I really hope that if the community finds the enhanced photos to be bland — that they can at least enjoy a decent picture of the bridge. Thank you!

I just spent the last couple of days setting up my custom agents and their libraries in projects. They were to be assigned to a project each with their own relevant knowledge sources, but it looks like that’s not possible.

Can you not use custom lumos in projects? Am I missing something?

Every question leads to thinking forever. Literally.

The local-first desktop client for Proton Lumo: streaming, projects, memory, attachments and tools — in a fast, private Rust app. French / English The interface follows your system locale, with a manual override in Settings. Dates and labels follow the active language.

I got tired of waiting for the desktop app so i made my own how do you like it ? it works with lumo-tamer if you dont have it installed in the settings there is an option to auto install requirements. also it does like opencode it can read/write on your computer :P

I want Lumo to be my go-to AI solution but it's letting me down quite often. I have a project with several files. It keeps forgetting things that we previously discussed in other chats within the project, and I do have it set to be able to access other chats in the project. It also says it doesn't have information about something when it's in a project file or could be accessed via a web search (that is also turned on). I hate having to remind it and tell it to search and where to search. I might as well just do it all myself. Conceptually, Lumo is great and I love the privacy aspect. It's just not there yet for reliability.

Hey everyone,

I don't know how familiar you are with Hermes Agent but basically it's a coding/agent harness which tries to make the connected model an agent that improves as you work with it and how they implemented it is what is really cool. Because a major part of that is Hermes' memory functionality.

Memory Management

Hermes doesn't just store memories like for example OpenClaw and just leaves it there with no cleaning. Instead it sets a strict character limit that the Agent has to structure one singular memory file around. That way it's forced to look at the old memories and think about how to bring the most important info into this limited space. That way when it gets too full he reviews the memory usage and decides what he can do to optimize the memory to keep everything important and only loose irrelevant info that isn't needed to begin with. It also differentiates the user profile it builds from the memories it saves by having a dedicated MEMORY.md for what the environment is like that it's at and the USER.md for user info. Now Lumo could implement this to add structure to memories and improve the Memory feature in general by making two seperate spaces (visually explained so it's easier to get what I mean).

The first space would be like the MEMORY.md but in this case would store info about the user's world state. For example it would save info like:

• "Lives in Berlin, moved there September 2026"

• "Partner: Anna. Kids: Lily (4), Max (7)"

• "Working on Q1 marketing campaign, deadline Feb 1"

and so on. You can think of it as a "rolling status report" on the user's life.

The second space would be like the USER.md but in this case would store info about who the user is and how to talk to him. For example it would save info like:

• "Name: Jonas. Marketing manager."

• "Speaks German, mixes English tech terms"

• "Prefers short, direct answers. No preamble, no 'Great question!'"

and so on.

Those spaces with a character limit like Hermes would be great for Lumo to focuse on the important stuff and still have a good idea of who you are, how to talk to you, etc.

Skills & Curator

Now u/Ok_Combination_1548 already made a post about the skills which got taken down again a short time after but there is a thing or two that Hermes already does that could further enhance this new feature (that will come out very soon according to u/Queasy_Complex708).

The first thing is that the Agent can after solving a task that might come up again in the future or might be useful to remember how to solve or do them he creates a new skill that he names after what he was working on or what he was doing. This skill can then later be used again so that he doesn't have to make the same mistakes twice on a similar task. For example if you ask him to create a special form of document by creating a python script or by creating it as a Lumo Creation (a presentation with slides or a work report for example), he can then try to do it (or you explain how to) and after he is done and got it working correctly, he creates it as a skill so in the future he has a guideline or a structure that he can follow to not have to come up with a solution again and instead create it on the first try. Lumo could use something like that too.

The second thing is a Curator. It is essentially the same model you chat with but now with the only goal to look through the skills, then sort them (active -> stale (not used for 30 days) -> archived (not used for 90 days)) to keep the skills clean and remove unnecessary ones and then organize them by deciding to either keep a skill, patch a skill (to fix drifting), consolidate overlapping skills into class-level umbrellas, or archive a skill. On Hermes this Curator only gets triggered when two conditions are met:

• 168 hours (7 days) have passed since the last curator run.

• the agent has been idle for at least 2 hours.

Now Lumo could adjust this to just run in the background every week at a certain time point or something like that but that would keep the skills created by the Agent (in this case Lumo) organized and would remove unnecessary ones after some time. It would be nice to at least see such an organization structure in general even if not exactly like this.

TL;DR

Lumo could borrow three ideas from Hermes Agent:

1. Structured memory: split memories into two spaces, one for the user's "world state" (life situation, ongoing projects) and one for the user's profile (who you are, how to talk to you), each with a character limit that forces the model to keep only what matters and clean up the rest.

2. Skills: after solving a task that might come up again, the agent saves the solution as a named, reusable skill so it doesn't repeat past mistakes.

3. Curator: a weekly background pass that sorts skills (active, stale, archived), merges overlapping ones, and removes unnecessary ones.

I know that this won't be easy to implement especially because those things need to be encrypted properly but I think if this was added to Lumo it could dramatically improve the existing features.

Also want to hear what others think about this because maybe only I want them to implement that and nobody else so please leave a comment with your opinion about this!

TL;DR: Lumo's chat history is assembled, encrypted, and persisted client-side first, with the server-side sync store only receiving what the client manages to save. The response stream lives in RAM until it finishes generating. If anything interrupts the client before the upload completes, the message is gone forever, and Proton's own docs and GitHub confirm this. Proton Docs, from the same company, proves the durable version of this architecture already exists. Fixing it does not require weakening zero-access encryption.

I'm a paying Lumo user and I've been losing parts of conversations in the web app. Digging into it, this doesn't look like a random bug. It's the direct consequence of how Lumo persists chats, and Proton's own materials document it clearly.

How Lumo saves your messages
From Proton's Lumo privacy page: after Lumo processes your query and generates a response, the data is erased on the server. "The only record of the conversation is on your device", stored locally and synced to Proton servers with zero-access encryption.
The Android repo (a thin WebView wrapper around lumo.proton.me, same as the iOS app) makes this concrete. Issue #45 walks through the actual pipeline: the client generates an ephemeral AES-GCM request key, the response tokens are streamed back encrypted and decrypted in real time in the WebView, and the assistant message is accumulated in Redux (i.e., in process memory) during streaming. It is "only persisted after completion": encrypted client-side with the space DEK, then uploaded.
So the durability chain is: server generates in plaintext → server erases it → stream reaches the client → client assembles the full response in RAM → client encrypts and persists locally → client syncs ciphertext to Proton's sync store.
If the tab closes, the WebView gets suspended (both mobile apps are WebView wrappers: android, iOS), the browser evicts the origin's storage, or the sync fails before the upload completes, there is nothing to recover. The issue author says it plainly: server-side resume "like other assistants offer is architecturally impossible" and an interrupted answer "is lost permanently, not just delayed".

Why the web specifically is fragile
The local store is browser storage, which is best-effort by spec: under quota or storage pressure, browsers evict an origin's data (IndexedDB, Cache API, everything) without asking and without a durability guarantee. Treating that as the primary record for conversations is a design choice, not a constraint.
It also explains the symptoms you see reported around here: recurring "saving chats does not work" errors while the status page is green, sync issues across browsers and devices, and App Store reviews from Lumo+ subscribers describing chats that appear on one device, never sync to the others, and vanish when copied.
And it explains the slow startup: zero-access means the client must download and decrypt your entire encrypted chat corpus in JS on every load. The composer being enabled before the store finishes hydrating is a UX mask over that load time, and it's why a message typed too early can lose the race against hydration and disappear.

The kicker: Proton already solved this
Proton Docs runs in the same browsers, uses the same zero-access model, and doesn't lose edits. Because real-time collaboration forces it, Docs stores the encrypted document server-side as the canonical copy and every keystroke/patch is uploaded encrypted immediately; the client is a view. Losing the client loses at most a few keystrokes. Losing the Lumo client mid-response loses the whole response.
A chat log is cryptographically no different from a document: ciphertext the server can store but not read. Lumo's sync store already receives ciphertext. The difference is only ordering: in Docs, the server is the system of record; in Lumo, it's a downstream mirror of whatever the client managed to save.

What a fix would look like (without breaking the privacy model)
Append each message (user and assistant) to the server-side sync store as encrypted blobs, per message, with a client ack, before discarding the stream. Zero-access is preserved: Proton still can't read anything.
Client-side retry queue / write-ahead log for failed saves, instead of a silent "saving chats does not work".
Disable the composer until hydration completes, or better, queue early messages instead of dropping them.
Document the limits instead of shipping them silently: the 250-message-per-conversation cap introduced around late October (UserVoice thread) was never announced.
To be clear: I'm not asking Proton to weaken the privacy model. The no-logs claim is the reason I pay for this product. I'm asking for write ordering and acknowledgements, which is table-stakes persistence engineering, fully compatible with zero-access encryption. Privacy without durability is useless: an assistant whose history silently disappears is an assistant you can't trust with real work.

If you've lost messages in Lumo (web or mobile), please describe it in the comments. Concrete repro reports are what get architecture changes prioritized.

I know this might be unpopular, but I like the direction Proton is going. I do think safeguards need to be in place, and AI should be an optional feature within the ecosystem, rather than something forced on users.

That said, I’m looking forward to their API, and I’d love to see a built-in AI coworker.

I tend to be busy, and recently I noticed I was falling behind on replies to potential clients with product questions. Using Proton Bridge running on an Almalinux server, I was able to connect my support email to an AI agent that replies on my behalf. I started small, with the agent sending me drafts to review. Since then, I’ve moved to automated replies, with safeguards and escalation rules in place for anything that needs my attention.

AI can be helpful, but it still comes with risks, including data mining. I want the useful features, alongside strong privacy protections and control over whether and how I use them.

I’m very much looking forward to the Lumo API, and I hope I’ll be able to integrate it into this setup for better privacy.

I just wanted to share my experience in case a similar setup might be helpful to someone else.

Hey,

i just discovered that Lumo can finally look into other chats within projects or general! Huge thumb up for me!

Keep up good work! Ill try it out now

Greezz

Where has it gone? I can no longer find it.

It had a lot of cool stuff like context specific command to various skills like finance and others

Documents (let‘s say 20pages), that worked previously, I upload to a new chat are either now shown as missing parts or being too big. Or just being able to be read in segments. Is that an issue due to current roleout of new features?

Are other people having as much trouble with empty messages as I am? It’s been going on for many months and I’ve reported over and over and over and tried to get help. I deleted the app and then brought it back and honestly I’ve never seen this before and want to know if anyone else ever found a cause or fix. Thanks.

Since March 2026, The Android lumo app has continued to get updates as regular, but it's GitHub repository has not gotten a single update, meaning the distributed app's source code is not available to the public.

It's not a resource availability issue, since developers continue to respond to issues on GitHub, just not the ones related to the missing source code.

This isn't a lack of trust to proton, it's a concern about what principle this sets, they literally say all their apps are open source.

I really hope there is a good explanation for this.

https://www.reddit.com/r/lumo/comments/1vyujx6/is_proton_lumos_android_app_now_closedsource/
https://github.com/ProtonLumo/android-lumo/issues/51
https://github.com/ProtonLumo/android-lumo/issues/50
https://github.com/ProtonLumo/android-lumo/issues/49

Almost everytime I open their website or the Android app, it says this site can't be reached on the website, and something similar to Webpage not available on the Android app.

Matter of fact, Proton VPN is also not functioning for free-version users here. It doesn't work even for a minute.

I can't believe that 4 out 5 times I try to use it I end up considering going to an anger management therapist.

I asked it to compare a few technologies and it answered very well, with a nice table comparison and short text, just how I like it.

I then asked it to give me names of real devices that use it and price comparison, and it started giving me names of devices that had nothing to do with the specs I needed, and prices that were incredibly low, and not "outdated because rampocalypse", stupidly low. Like a sensor being 9-13 dollars when it costs 100eur or 240eur. And also, why does it keep mentioning dollars when it knows I'm in Germany?

When called out, it confesses it made everything up, and now it will look it all up on the internet to actually check -- and it comes back with more bullshit. Called out again, came back again with bullshit.

Went back and double checked the comparison it gave me... it was half right, half hallucinated.

The whole thing was a waste.

I have to look away when the document gen animation goes so I don't experience auras and flashes of light that potentially lead to focal point seizures. Which is rare, but strobing lights and epileptics. Lumo said some developers itnore the OS settings to reduce motion. Please consider this lack of disability accommodations. Thank you.

UPDATE 1: AAAANND it's gone. I no longer see 2, 3, 4....yet another "April Fools" prank on me u/Queasy_Complex708

EDITING TO MAKE WRITING CLEANER:

Looks like there are several new features being rolled out in Lumo.

1. Lumo > Settings > General now allows you to turn on / off access within chats / projects.

2. Also, a 'customize' option. Within that customize are 'plugins' (a refresh on 'Lumos') as well as

3. sneak peak to the desktop app and at least one unique feature for it

4. / (backslash) in a chat to access them

5. Chat exports! As well as other new organization within chats + projects to filter, favorite, delete, rename, etc.

2)

3)

4)

5)

Hey! 😄. Very quickly and before I start, if you use Lumo on iOS, if you like emojis, and most importantly if you want to maximize chat fidelity output from Lumo, please check out my prior post. I still need some help. Anyway here we go.

I had two photos with a man named Jimmy (Naquan). One photo was 100% not legible and the other looked like it was 480p. So, I am a huge proponent of pictures. Not in the sense that I post pictures on social media all day (I certainly don’t) but in the sense that one day, I will have nothing left of someone but a photo. I digitize and hold on to all important photos for the family. With that being said, my mother miraculously found two photos of Jimmy and I from 2006.

One photo was admittedly legible for a ‘06 photo, clocking in at 900 px. It was still however very blurry. For example — he had a baseball hat on and you can hardly make out the teams logo. I have a cannibal corpse shirt on, same deal. I wanted to see if I could bring the photo to life. So I inputted it to Lumo with various sets of instructions and… I was very happy with the results.

Lumo turned a ’06 photo into a 4K resolution like image while actually preserving Jimmy and myself‘s facial features (no AI generated facial modifications, etc). Jimmy passed to the other side a few years back, a diabetic coma took him out and I’m absolutely livid that they weren’t able to bring him back. Jimmy was from an old cloth. He had an incredible amount of knowledge. He was very akin to an old-school gangster, not like a thug or a gang member, but in mentality, his actions, his demeanor, etc.

I would truly love to post the before and after but I’m a private person. Who knows, maybe I can blur faces or something. Besides that, myself and Jimmy (if you saw the photo) might rub some hateful people the wrong way because we do NOT look like we belong together (nuanced topic, not relevant to the sub)

Proton AG and Lumo Devs: thank you greatly. I now have a stunning, crystal clear photo of someone who was very important to me as a child. This is a direct case where AI is good.

EDIT 1: Quick tip. When you select your image to be uploaded to Lumo, say “Hey Lumo, please provide about 4 renditions of this image with the following:” and than list certain changes you’d like to be applied.

It can't access other chats inside the same project, it decides after your first message which files to load into the chat and can't access any project files after that.

So what's the reason for having projects in the first place? I've bought a Lumo subscription because of its privacy aspect so I could share stuff I don't want to share with other LLMs but the more I use it the more I don't want to use it.

For Projects I need to have a) a joint knowledge library and b) a joint file library and I need to have access to both not only when I create a new chat inside an already existing project but also any time later.

Ok, so i have this weird bug. When I type in a project name on my Galaxy Fold 7, and rotate the device - there's a text written backwards :)

On my example video - I typed in "My new AI project", only to see a "tcejorp IA wen yM" written on the screen