---
id: ML-179.1
title: Tighten Presto main loop navigation and event structure
status: To Do
assignee: []
created_date: "2026-05-10 20:30"
updated_date: "2026-05-11 06:44"
labels:
  - presto
dependencies: []
documentation:
  - presto/AGENTS.md
  - presto/README.md
  - docs/project-conventions.md
modified_files:
  - presto/main.py
parent_task_id: ML-179
priority: medium
ordinal: 7000
---

## Description

<!-- SECTION:DESCRIPTION:BEGIN -->

Follow-up to ML-179. Continue the single-file, behavior-preserving Presto refactor by completing transition cleanup, moving per-screen event branches out of main(), replacing per-gesture lambda scroll call sites with named wrappers, centralizing common hit tests, and adding explicit reset helpers for grouped state. Keep deployment as one presto/main.py file and avoid user-facing behavior changes.

<!-- SECTION:DESCRIPTION:END -->

## Acceptance Criteria

<!-- AC:BEGIN -->

- [ ] #1 All screen transitions in presto/main.py go through navigation helpers or narrowly named transition helpers; direct app.screen assignments outside initialization/navigation are removed.
- [ ] #2 main() remains responsible for boot, sleep/wake, debounce, and top-level dispatch, while search-results, day, and record event handling live in dedicated helper functions.
- [ ] #3 Day, search-results, and record-detail scroll handling use named wrapper functions instead of inline lambda closures at the main dispatch call sites.
- [ ] #4 Shared touch geometry checks such as back, home, and month navigation buttons are centralized in small hit-test helpers and used consistently by handlers.
- [ ] #5 Grouped state reset behavior is expressed through reset helpers or methods for day, search results, and detail state, preserving the existing reset semantics.
- [ ] #6 The change is behavior-preserving for home, month, day, search, record detail, display sleep/wake, image placeholder, and scrobble flows.
- [ ] #7 Presto syntax verification passes with python3 py_compile from the presto directory, and final notes state whether physical-device behavior was verified.
<!-- AC:END -->

## Implementation Plan

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1. Inspect the current post-ML-179 `presto/main.py` event dispatch and identify remaining direct screen assignments, duplicated button geometry checks, and inline scroll lambdas.
2. Add small reset helpers or state methods for day-list, search-results, and detail state; update existing navigation helpers to call them without changing reset behavior.
3. Add shared hit-test helpers for common button geometry, including back, home, previous-month, and next-month controls; replace duplicated coordinate checks in main-loop branches and handlers.
4. Add named scroll wrapper functions for search results, day records, and record detail that call the existing shared vertical-drag helper with the correct state accessors and redraw callbacks.
5. Extract search-results, day, and record event branches from `main()` into dedicated event helper functions while keeping boot, sleep/wake, debounce, and top-level screen dispatch in `main()`.
6. Run the Presto syntax check from `presto/` using `python3 -c "import py_compile; py_compile.compile('main.py', cfile='/tmp/main.pyc', doraise=True)"` and record whether physical-device behavior was verified.
<!-- SECTION:PLAN:END -->