music_library/backlog/tasks/ml-179.1 - Tighten-Presto-main-loop-navigation-and-event-structure.md

id, title, status, assignee, created_date, updated_date, labels, dependencies, documentation, modified_files, parent_task_id, priority, ordinal

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

Description

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.

Acceptance Criteria

• #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.

Implementation Plan

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.