--- id: ML-197 title: Provide Elm-style Presto Music Library application status: Done assignee: - Codex created_date: "2026-05-26 05:39" updated_date: "2026-05-26 05:56" labels: - presto dependencies: [] documentation: - presto/AGENTS.md - presto/README.md - presto/poc.py - presto/main.py - presto/tests/test_screens.py - presto/mise.toml modified_files: - presto/music_library.py - presto/tests/conftest.py - presto/tests/test_screens.py - presto/tests/test_music_library_architecture.py - presto/mise.toml - presto/README.md priority: medium ordinal: 30000 --- ## Description Add an alternative Presto Music Library application organized around the message/update/view architecture demonstrated by the local proof of concept, while retaining the user-facing behavior of the existing device application. ## Acceptance Criteria - [x] #1 A `music_library.py` application exposes the existing Home, calendar/day browsing, search, record detail, scrobble, network error, and display sleep interactions through the Elm-style runtime. - [x] #2 Scrolling, cover loading, wake handling, and API request behavior remain consistent with the current Presto app constraints. - [x] #3 Headless verification covers the new application screens and prevents accidental network access during render tests. - [x] #4 User-facing or deployment documentation is updated if introducing the alternative application changes available usage or verification instructions. ## Implementation Plan 1. Add a standalone `presto/music_library.py` entrypoint that remains deployable as device `main.py`, retaining the current screens, layout, API behavior, cached cover handling, scroll throttling, partial updates, and sleep/wake behavior. 2. Reshape application control flow around the POC contract: application model/runtime state, message constants, effect constants, pure state transitions in `update()`, hardware polling in `wire_events()`, effect execution in `run_effect()`, queued dispatch, and screen rendering in `render()`. 3. Keep network activity out of render hot paths in the new entrypoint, including routing initial detail-cover loading through an effect before detail rendering while using cached/placeholder imagery during drag redraws. 4. Extend emulator coverage for `music_library.py`, retaining the render/partial-update/image safety contracts and adding focused coverage of message/effect orchestration. 5. Add a deployment task for the architecture-based entrypoint and update `presto/README.md` with its optional deployment and verification path; no root architecture or production-infrastructure update is required because the API/default app contract is unchanged. 6. Verify with syntax compilation and `mise run test`; do not claim physical device behavior without hardware testing. ## Implementation Notes Read the project architecture, Presto guidance, README, project conventions, available task guidance, and testing skill before implementation. The change is scoped as one focused port with verification. Inspected `presto/poc.py`, `presto/main.py`, test harness, and `presto/mise.toml`. The POC boundary is `Model`/`Runtime` plus messages, `update`, commands, `dispatch`, `run_effect`, and `render`; the current app invokes navigation/network/redraw directly in its polling loop. `main.py` also downloads the medium detail cover from drawing code, which should be preloaded by an effect in the new entrypoint to preserve a render-only view path. Existing smoke tests assert display regions, cover-size contracts, drag placeholders, and every visible screen. User approved the implementation plan on 2026-05-26 and requested that this task record be committed before application work begins. Implemented the standalone architecture-based entrypoint with `Model`/`Runtime`, message-driven transitions, command dispatch/effects, centralized rendering, prepared detail-cover effects, nonblocking drag messages, display sleep/wake consumption, API loading/reconnect effects, and scrobble feedback effects. Extended the emulator screen contract suite to cover both `main.py` and `music_library.py`, and added focused tests for the status state, render-without-cover-fetch, detail preparation messages, wake consumption, WiFi reconnect before search, and throttled drag updates. Added optional deployment documentation and a `music_library` mise deploy task. A compatible concurrent change switching the emulator task target to `music_library.py` was present in `presto/mise.toml`; it is not part of the agent-authored deploy-task hunk and will be left unstaged. Verified `main.py` and `music_library.py` with `py_compile` output directed to `/tmp`; verified the headless suite with `mise run test` (36 passed). Physical Presto hardware was not tested. ## Final Summary ## Summary - Added `presto/music_library.py`, a standalone Music Library entrypoint organized around the Elm-style `Model` / `Runtime` / message / effect / render architecture while preserving the current UI and API interactions. - Routed blocking requests and detail-cover preparation through effects, retaining cached or placeholder-only redraw behavior during scroll interactions and wake/sleep handling. - Added deployment/documentation support and expanded emulator coverage to exercise both entrypoints plus the architecture-specific event/effect behavior. ## Verification - `python3 -c "import py_compile; py_compile.compile('main.py', cfile='/tmp/main.pyc', doraise=True); py_compile.compile('music_library.py', cfile='/tmp/music_library.pyc', doraise=True)"` - `mise run test` (36 passed) ## Remaining Validation - The architecture-based entrypoint has not been exercised on a physical Pimoroni Presto device.