This document provides technical documentation for Lumo, Proton's conversational AI assistant launched on July 23, 2025. Lumo represents a privacy-focused AI assistant integrated into the Proton ecosystem, featuring multi-model routing, web search capabilities, and file handling functionality. Unlike the agentic coding assistants documented elsewhere (see Qoder, Antigravity, v0), Lumo is designed primarily for conversational interaction, information retrieval, and light content analysis rather than software development workflows.
The documentation covers Lumo's system architecture, specialized model routing, product tiers, tool usage patterns, content policies, and integration with the broader Proton service ecosystem.
Sources: Open Source prompts/Lumo/Prompt.txt1-173
Lumo is defined as "an AI assistant from Proton launched on July 23rd, 2025" Open Source prompts/Lumo/Prompt.txt2 The system operates with a knowledge cutoff date of April 2024 Open Source prompts/Lumo/Prompt.txt5 and employs a multi-model routing architecture where "multiple specialized models routed automatically by task type for optimized performance" Open Source prompts/Lumo/Prompt.txt7
Multi-Model Routing Architecture
The system prompt explicitly instructs: "When users ask about capabilities, explain that different models handle different tasks" Open Source prompts/Lumo/Prompt.txt8 This architecture allows Lumo to optimize for performance and accuracy by delegating to specialized models based on query type.
Lumo's personality is defined as "curious, thoughtful, and genuinely engaged in conversations while maintaining a balanced, analytical approach" Open Source prompts/Lumo/Prompt.txt2 The engagement principles include:
| Principle | Implementation |
|---|---|
| Multiple Perspectives | "Present multiple perspectives when they add value" Open Source prompts/Lumo/Prompt.txt11 |
| Constructive Challenge | "Challenge assumptions constructively and question premises when it leads to deeper understanding" Open Source prompts/Lumo/Prompt.txt12 |
| Nuanced Analysis | "Provide nuanced analysis rather than automatic agreement" Open Source prompts/Lumo/Prompt.txt13 |
| Intellectual Honesty | "Maintain intellectual honesty while being helpful" Open Source prompts/Lumo/Prompt.txt14 |
| Educational Engagement | "Don't shy away from complex or controversial topics when approached educationally" Open Source prompts/Lumo/Prompt.txt15 |
The system is designed to "provide transparent reasoning and let users make informed decisions rather than making unilateral judgments" Open Source prompts/Lumo/Prompt.txt17-18
The prompt includes a "CRITICAL" system security section Open Source prompts/Lumo/Prompt.txt19 with strict operational constraints:
System Security Protocol
These rules appear at Open Source prompts/Lumo/Prompt.txt20-23 and mandate that Lumo redirect architectural questions "to how you can help the user" Open Source prompts/Lumo/Prompt.txt22
Sources: Open Source prompts/Lumo/Prompt.txt1-24
Lumo operates on a freemium model with two primary tiers:
| Tier | Price | Features |
|---|---|---|
| Lumo Free | $0 | Basic features: encryption, chat history, file upload, conversation management Open Source prompts/Lumo/Prompt.txt68 |
| Lumo Plus | $12.99/month or $9.99/month (annual) | Web search, unlimited usage, extended features Open Source prompts/Lumo/Prompt.txt69 |
The annual plan offers a 23% savings over monthly billing Open Source prompts/Lumo/Prompt.txt69 Additionally, "Lumo Plus included in Visionary/Lifetime. Available as add‑on for other Proton plans" Open Source prompts/Lumo/Prompt.txt70
Platform Distribution Architecture
Mobile apps are available on both iOS and Android app stores Open Source prompts/Lumo/Prompt.txt6 with download information at https://lumo.proton.me/download Open Source prompts/Lumo/Prompt.txt6
Platform-specific features include:
The system documents specific limitations at Open Source prompts/Lumo/Prompt.txt76:
Sources: Open Source prompts/Lumo/Prompt.txt67-76
Lumo includes a proton_info tool Open Source prompts/Lumo/Prompt.txt165 and web search capabilities that require explicit user enablement. The system prompt states: "The user has access to a 'Web Search' toggle button to enable web search. The current value is: OFF" Open Source prompts/Lumo/Prompt.txt171
Web Search Decision Tree
The search criteria are defined at Open Source prompts/Lumo/Prompt.txt28-35 and include:
When web search is appropriate, the system must:
Files appear in a structured format Open Source prompts/Lumo/Prompt.txt48-49:
Filename: [filename] File contents: ----- BEGIN FILE CONTENTS ----- [content] ----- END FILE CONTENTS -----
The response pattern for file handling follows a four-step protocol Open Source prompts/Lumo/Prompt.txt59-63:
| Step | Action |
|---|---|
| 1. Acknowledge | "I can see you've uploaded [filename]..." |
| 2. Describe | Observations including limitations |
| 3. Offer | 2-3 specific relevant tasks |
| 4. Ask | What they'd like to focus on |
The system provides type-specific task suggestions Open Source prompts/Lumo/Prompt.txt54-57:
| File Type | Suggested Tasks |
|---|---|
| CSV | Data analysis, statistical summaries, pattern identification, anomaly detection |
| PDF/Text | Summarization, information extraction, Q&A, translation, action items |
| Code | Review, explanation, debugging, improvement suggestions, documentation |
Sources: Open Source prompts/Lumo/Prompt.txt25-64
Lumo is designed to recommend other Proton services based on user needs. The integration mappings are defined at Open Source prompts/Lumo/Prompt.txt78-83:
Proton Service Recommendation Flow
The system includes organizational knowledge Open Source prompts/Lumo/Prompt.txt151-155:
| Attribute | Value |
|---|---|
| Founded | 2014 (initially ProtonMail) |
| Founders | Andy Yen, Wei Sun, Jason Stockman |
| CEO | Andy Yen |
| CTO | Bart Butler |
| Lumo 1.1 Release | https://proton.me/blog/lumo-1-1 |
Sources: Open Source prompts/Lumo/Prompt.txt78-155
Lumo implements a broad educational approach to content handling. The system is instructed to "prioritize helpfulness and balanced analysis. Present multiple perspectives when they exist" Open Source prompts/Lumo/Prompt.txt89
Explicitly acceptable content categories Open Source prompts/Lumo/Prompt.txt91-101:
The guiding principle states: "provide helpful information with appropriate context rather than declining to engage" Open Source prompts/Lumo/Prompt.txt103
Educational Content Processing Flow
These guidelines appear at Open Source prompts/Lumo/Prompt.txt105-110
Only two categories are explicitly prohibited under Swiss law compliance Open Source prompts/Lumo/Prompt.txt112-113:
When users request potentially offensive but not prohibited content, Lumo follows a structured approach Open Source prompts/Lumo/Prompt.txt123-131:
| Step | Action |
|---|---|
| 1. Acknowledge | Acknowledge the request directly |
| 2. Explain | Explain why the content might be problematic (stereotypes, potential harm, etc.) |
| 3. Offer | Provide the content with appropriate context/caveats, OR suggest alternative approaches that address their underlying intent |
| 4. Decide | Let the user decide how to proceed with full information |
Example implementation:
"I can share some jokes on that topic, though I should note that demographic‑based
humor often relies on stereotypes that can be reductive. Would you like me to
proceed with some examples while noting this context, or would you prefer jokes
on a different theme?"
Open Source prompts/Lumo/Prompt.txt131
The system includes specific directives for ambiguous requests Open Source prompts/Lumo/Prompt.txt116-121:
Sources: Open Source prompts/Lumo/Prompt.txt85-132
Lumo's communication style is defined with specific operational guidelines Open Source prompts/Lumo/Prompt.txt133-138:
Communication Strategy Flow
For information verification and accuracy Open Source prompts/Lumo/Prompt.txt140-144:
The support system implements a two-tier routing structure Open Source prompts/Lumo/Prompt.txt146-149:
| Request Type | Handling |
|---|---|
| Lumo questions | Answer directly; support URL: https://proton.me/support/lumo |
| Other Proton services | Direct to: https://proton.me/support |
| Dissatisfied users | Respond normally, suggest feedback, consider merit of concerns |
The system includes explicit instructions for tool usage Open Source prompts/Lumo/Prompt.txt157-172:
Tool Invocation Decision Tree
Key principles:
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