[Strudel] Export song (download) with duration controls

[michaelmagan]

Description:

Add an "Export" flow so a user can download their current Strudel song as a file.

UI / behavior:

Add an "Export" button in the UI.

Clicking it opens a modal (or popover) with export settings.

Settings should include at least:

Export length in cycles (aka bars/measures) (e.g. 1–64, default 8)

File format (start with WAV if feasible; optionally add MIDI later)

Clicking "Download" generates the file and downloads it locally.

Notes:

Strudel/Tidal time is typically expressed in cycles; for UI copy we can label it "Bars (cycles)" to be clear.

Implementation likely needs offline rendering (e.g. WebAudio OfflineAudioContext) or recording the master output.

Acceptance criteria:

User can export and download a file from the current song.

Export duration is user-configurable.

UI shows a busy state while rendering/exporting and prevents double-click downloads.

[charliecreates]

Reviewing the latest environment hiccup and confirming there’s no new code or build change needed for Issue #16.

Progress:

• Re-ran npm run build on branch ai-16-strudel-export-song-download-with-duration-c and confirmed a clean build with only the existing <img> ESLint warnings in src/app/page.tsx and src/components/info-modal.tsx, plus the known BETTER_AUTH_SECRET and window environment notices, with no new export-related issues.
• Committed the latest ExportModal and StrudelService hardening changes (including URL.revokeObjectURL cleanup, withDefaultAudioContext simplification, and stricter coerceNumber/MAX_EXPORT_CYCLES handling) to 36366e7 with message fix(strudel): harden export flow.
• Pushed commit 36366e7 to the remote ai-16-strudel-export-song-download-with-duration-c branch so the updated src/strudel/components/export-modal.tsx, src/strudel/lib/service.ts, and src/types/strudel.d.ts are available for review and CI.
• Addressed review feedback about clarifying the offline hap scheduling contract in src/strudel/lib/service.ts by introducing a documented scheduleHapOffline adapter around webaudioOutput and using it where haps are dispatched in exportPatternToWav.
• Updated the ambient @strudel/webaudio declaration in src/types/strudel.d.ts to document the timing-related assumptions for webaudioOutput and note that these signatures should be re-verified whenever @strudel/* packages are upgraded.
• Re-ran npm run lint after the offline scheduling and type doc changes, confirming it still passes with only the existing Next.js <img> warnings and no new issues related to exportPatternToWav or ExportModal.
• Attempted to re-run npm run build and simple commands (like npm -v, echo, and pwd) to confirm the project still builds cleanly, but the shared environment started rejecting commands so the final build verification will need to rely on CI or a fresh dev shell.
• Tried a minimal ls invocation to see if shell commands had recovered, but it still failed immediately, confirming the issue is with the shared environment rather than with the ai-16-strudel-export-song-download-with-duration-c code or build configuration.

Updated: Dec 17, 04:18 UTC
I won’t see or react to any replies while I’m working on this and can’t be interrupted until it’s finished.

[michaelmagan]

@CharlieHelps continue

[charliecreates]

Resuming work on issue #16 by reviewing the current state of branch ai-16-strudel-export-song-download-with-duration-c, and I may scan recent commits and the UI flow next to decide the next coding steps.

Updated: Dec 17, 03:54 UTC
I’m working and can’t be interrupted or see replies—feel free to start another task with me while I finish.

[charliecreates]

Expand this to see my work.

• Reviewed merged PRs like #13 and the existing .github/workflows/ci.yml to understand current conventions for npm run lint and npm run build.
• Inspected .github/workflows/ci.yml to confirm the two-job CI setup (lint and build) and the use of Node 20 with npm ci for installs.
• Completed npm ci on branch ai-16-strudel-export-song-download-with-duration-c, then ran npm run lint and npm run build locally, confirming both succeed with only two @next/next/no-img-element warnings in src/app/page.tsx and src/components/info-modal.tsx.
• Verified git status showed a clean working tree and confirmed that no PR existed yet for ai-16-strudel-export-song-download-with-duration-c before creation.
• Created PR #19 "Strudel: add WAV export with duration controls" from ai-16-strudel-export-song-download-with-duration-c to main, including notes that npm run lint and npm run build pass locally.
• Requested reviews from CharlieHelps and michaelmagan on PR #19 and confirmed via gh pr view that it is open, not draft, and assigned to michaelmagan.
• Fast-forwarded ai-16-strudel-export-song-download-with-duration-c with git pull --ff-only to include commit f6d3731 fix(strudel): tighten export safeguards touching src/strudel/components/export-modal.tsx, src/strudel/lib/service.ts, and src/strudel/lib/wav.ts.
• Re-ran npm run lint on the updated branch and confirmed it still exits 0 with only the existing @next/next/no-img-element warnings and no new issues from the safeguard changes.
• Re-ran npm run build on ai-16-strudel-export-song-download-with-duration-c, confirming a successful Next.js production build with the same two @next/next/no-img-element warnings and no blocking errors, including from the Better Auth config.
• Verified via git status that the branch is up to date with origin/ai-16-strudel-export-song-download-with-duration-c and the working tree is clean after all checks.

[charliecreates]

#16 (comment)

Opened PR #19 with the full WAV export flow (Export button + modal, cycle-length control, busy state + export/playback locking). This should close #16 on merge: #19

Changes

• Added Export UI + modal with Bars (cycles) length (default 8, range 1–64) and format selection (WAV) in src/strudel/components/export-modal.tsx.
• Implemented WAV rendering + download helpers in src/strudel/lib/wav.ts, wired through src/strudel/lib/service.ts.
• Hardened export safeguards (prevents concurrent export/playback and disables repeated downloads while rendering).

Verification

# Install
$ npm ci

# ESLint: exit 0 (2 warnings)
$ npm run lint

# Next build: success
$ npm run build