---
source: marlvel.ai
type: app_intelligence_report
app_name: "Sumi: Deep Work Focus"
slug: "sumi-deep-work-focus"
category: "Productivity"
category_slug: "productivity"
developer: "David Park"
bundle_id: "com.kindauseful.thephoneislava"
rating: 3.00
rating_count: 2
generated_at: 2026-08-07T12:47:57.587Z
last_verified: 2026-08-07T12:47:57.587Z
canonical_url: "https://marlvel.ai/apps/sumi-deep-work-focus"
license: CC-BY-NC-4.0
citation: "Marlvel.ai - Sumi: Deep Work Focus Intelligence Report"
---

# Sumi: Deep Work Focus

Sumi targets the minimalist productivity segment by enforcing deep work through a binary session-tracking mechanism, but its technical instability (timer termination during active use) creates a high churn risk that outweighs its aesthetic appeal. The app serves writers and developers who romanticize focus, yet the current inability to maintain session state while the phone is in use undermines the core value proposition of a "quiet ledger" [1].

### Feature Analysis

*   **Focus Session Tracking**: Records lifetime hours focused; acts as a retention loop by providing a visual progress record [1].
*   **Session Interruption Penalty**: Ends sessions if the user leaves the app or lifts the phone; reinforces the deep-work brand identity [1].
*   **Custom Session Lengths**: Gated behind a one-time Lifetime unlock or subscription; serves as the primary paid-conversion lever [1].
*   **Advanced Trends and Themes**: Historical data visualization gated behind premium tiers; incentivizes conversion for power users [1].

### User Sentiment Intelligence

*   **Overall Sentiment**: Mixed (3.0 stars from 1 review) [1].
*   **Top Praises**: Users appreciate the initial app concept and the session timer hook [1].
*   **Top Complaints**: Active session timers terminate prematurely when the screen is open or the app is active, which prevents the timer from maintaining state [1].

### Company Profile

*   **Developer**: David Park
*   **Website**: [https://dayonefoundry.com/sumi](https://dayonefoundry.com/sumi)

### Key Takeaways

*   The timer defect is a critical churn risk that must be resolved before scaling acquisition.
*   The premium-tier gating strategy is sound, but conversion requires a stable core experience.