Purpose
Canthus exists to help chronically ill people manage the tasks in their life in a sustainable way. Providing a system that works with the user to acheive the best they can. We help people understand their capacity, protect it, and move at a pace their body can sustain. Every decision about features, copy, and metrics must be tested against this. We treat users as competent adults. We never patronise or paternalise. That is a common thread among services focused towards chronically ill people and others with mental or physical capacity issues.Anti-goals
These are things Canthus must never optimise for or inadvertently encourage.Banned UI patterns
- Streaks of any kind
- Overdue badges, red indicators, or guilt-inducing visual states
- Shaming or comparative copy (“You only completed 2 tasks this week”)
- Notifications designed to create urgency or anxiety
- Any mechanic that rewards doing more over doing sustainably
Metric pitfalls to avoid
- Measuring success by tasks completed or mana spent
- Surfacing completion rates in ways that create pressure
- Framing low activity days as failures
- Social comparison: leaderboards, rankings, etc.
Glossary
Key terms with their intended user-facing meaning and usage guidance.Mana
Mana
The user’s available capacity for a given day or period. Mana is finite and replenishes - it is not a score. Never frame mana as something to maximise. Frame it as something to spend wisely and protect.
Baseline
Baseline
This term is used by chronically ill people to describe their average state - their expected capacity on a standard day.Baseline in our usage refers to the capacity for activity/tasks on a day where the user feels they are at their baseline. This is a subjective measure, and should be treated accordingly.We should use this term in user-facing copy. This term is a well-known term that treats our users as the competent adults they are.
Check-in (relative)
Check-in (relative)
A check-in that captures how the user feels relative to their baseline (see above), not an absolute scale.“How are you compared to usual?” rather than “Rate yourself out of 10.”
Pool vs cost adjustment
Pool vs cost adjustment
Pool refers to the total mana available. Cost refers to what an individual task draws from the pool. These are adjusted separately: a bad night might reduce the pool; a flare might increase task costs. Never conflate the two.
Actionable vs non-actionable
Actionable vs non-actionable
Actionable tasks are ones the user can choose to do or defer today. Non-actionable items (e.g. waiting on someone else, future-dated commitments) should not sit in the active view - they create visual noise and false pressure.
Success metrics
These metrics must not reward overexertion. They measure whether the app is helping users pace sustainably.| Metric | Direction | Notes |
|---|---|---|
| Reduced distress interactions | Down | Fewer moments where the user expresses overwhelm or distress in check-ins |
| Stable adherence | Flat / consistent | Consistency over time matters more than high completion on any single day |
| Fewer crash cycles | Down | Reduction in boom-bust patterns (high activity followed by forced rest) |
| Check-in completion rate | Up | Indicates the app is part of a sustainable routine, not being avoided |
| Task deferral without guilt | Up | Users who defer tasks without distress signals are pacing well |