fix(editor): a MIDI file is a project — MIDI-only create + real multitrack unpack

[ChrisBeWithYou]

What

A MIDI file is a project now. Reported with dkcjungle-2.mid (format 1, 20 tracks): "why can't the editor upload this file and unpack it?" The backend parsed it fine all along — the create modal was the dead end, three ways deep:

1. _stageMidi recorded only the name; the staged File was dropped on the floor.
2. _createGateOpen never opened for MIDI-only — Create stayed disabled forever.
3. Even the "+Keys later" path made you re-pick the file — where multi-select silently imported only the first track ("MIDI keys import is single-track").

The flow now

Stage a .mid → the title pre-fills from the filename → Create enables → Create runs a draft create and opens straight into the track picker with the file already parsed (no re-pick) → check any number of tracks → every one imports as its own chart track, named after its MIDI track under a keys-safe prefix (Keys — Rumble in da jungle) → the temporary placeholder the draft create needed is removed automatically once real tracks land → the MIDI's own tempo map is offered as the project grid, as before.

Load-bearing details

• Keys-safe naming is not cosmetic: kind inference is name-driven and the imported notes use the roll's keys packing — a part named bare Bass, Baby. would render that packing as fretted lanes (garbage). _midiKeysArrNamePure pins the contract.
• One batch request, not a per-track loop: import-keys-midi rmtrees its temp dir after responding, so a request loop found no file on track two. The endpoint now accepts tracks: [{index, channel_filter}] and converts everything before the one cleanup; the legacy single-track body is unchanged.
• The placeholder is removed only when provably untouched (_midiSeedRemovablePure: flagged index, seeded name, zero notes/chords, never the last part) — user work always stays. The seed is Lead because the draft-create backend accepts Lead/Rhythm/Bass rosters only today.
• A user-modified roster is real intent and is kept (their parts + the MIDI tracks); only the modal's untouched ['Lead'] boilerplate is replaced.

Testing

tests/midi_create.test.mjs (3 cases, fails on main) + the create-gate suite gains the MIDI-stage case. Full gates green: 159 JS files / 0 fail, pytest 256, lint at baseline. Live-verified with the reported file itself: staged → Create → picker auto-opened with all 15 note-bearing tracks → 3 selected → Keys — Rumble in da jungle (257 notes), Keys — Cheap Xylophone (208), Keys — Diddlydiddlydiddlydiddladeedade (17) — placeholder gone, zero page errors.

🤖 Generated with Claude Code

https://claude.ai/code/session_01EBQCHCNA81E9tHmSDHSe2Q

Summary by CodeRabbit

• New Features
  • Create new songs directly from staged MIDI files—Create now opens with MIDI-only input, seeds the flow, parses MIDI up-front, and pre-fills the title from the filename.
  • When importing, you can select multiple MIDI tracks to generate separate chart tracks per checked MIDI track (preserving selection order and names).
• Bug Fixes
  • Improved cleanup and safety for MIDI-only placeholder/seed arrangements, including conditional removal to prevent accidental deletion.
• Tests
  • Added regression coverage for MIDI staging, title/name derivation, multitrack import selection, and seed/roster cleanup/provenance behavior.

[coderabbitai]

Caution

Review failed

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ℹ️ Recent review info

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Configuration used: defaults

Review profile: CHILL

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Reviewing files that changed from the base of the PR and between a75deb1 and efa56e3.

📒 Files selected for processing (5)

• CHANGELOG.md
• routes.py
• src/create.js
• src/import.js
• src/main.js

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📝 Walkthrough

Walkthrough

MIDI uploads can now open the Create flow, derive a project title, and enter the Keys track picker. Selected MIDI tracks are imported in batches as separate arrangements, with temporary seed cleanup and supporting tests.

Changes

MIDI creation and multitrack import

Layer / File(s)	Summary
MIDI-only create entry src/create.js, src/import.js, src/main.js	MIDI staging enables creation, derives a default title, routes files through the Keys picker, tracks roster provenance, and clears staged data when removed.
Batch Keys import and seed cleanup routes.py, src/import.js	The MIDI endpoint converts selected tracks in one request and returns ordered arrangements; the editor names imported tracks and removes an untouched placeholder arrangement.
MIDI validation and workflow coverage tests/create_gate.test.mjs, tests/midi_create.test.mjs, CHANGELOG.md	Tests cover staging, naming, batch selection, provenance-based cleanup, and create gating; the changelog records the workflow.

Estimated code review effort: 4 (Complex) | ~45 minutes

Sequence Diagram(s)

sequenceDiagram
  participant CreateModal
  participant KeysPicker
  participant ImportEndpoint
  participant EditorState
  CreateModal->>KeysPicker: open with staged MIDI file
  KeysPicker->>ImportEndpoint: submit selected track indexes and filters
  ImportEndpoint-->>KeysPicker: return arrangements and tempo_map
  KeysPicker->>EditorState: append named arrangements and remove seed placeholder

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Possibly related PRs

• got-feedBack/feedBack-plugin-editor#127: Related MIDI import tempo-map handling.
• got-feedBack/feedBack-plugin-editor#181: Related Add Keys MIDI import pipeline changes.
• got-feedBack/feedBack-plugin-editor#210: Related create-flow lifecycle changes used by MIDI-only creation.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly captures the main change: MIDI-only project creation plus true multitrack MIDI unpacking.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

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• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/editor-midi-create

---

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[coderabbitai]

Actionable comments posted: 3

🧹 Nitpick comments (1)

routes.py (1)

5792-5847: 🩺 Stability & Availability | 🔵 Trivial | 🏗️ Heavy lift

Batch conversion is all-or-nothing — one bad track fails the whole selection.

_convert() runs every selected track in a single worker call; if any one _convert_one() raises (bad track index, corrupt data, etc.), the exception aborts the entire batch and none of the already-converted tracks are returned — the user sees one generic 500 and has to retry the whole selection. Given this endpoint now accepts up to 64 tracks in one request, a per-track failure isolation (catch inside the loop, return partial results + a failed list) would give a much better multitrack-import experience, at the cost of a response-shape change on both ends.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@routes.py` around lines 5792 - 5847, Update _convert and its response
handling so _convert_one failures are isolated per selected track: catch each
track’s exception inside the batch loop, retain successful conversions, and
collect failed track identifiers and error details in a failed list. Return
partial results with the new failed field while preserving tempo_map generation
and successful track output; update the consuming frontend response handling to
accept and surface the changed response shape instead of returning a single 500
for one failed track.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/create.js`:
- Around line 1864-1889: Update the MIDI import flow around _editorDoBlankCreate
to track whether the roster is untouched boilerplate separately from the actual
roster value, so an intentional Lead-only selection is preserved and only the
default placeholder is marked for cleanup. Process all staged files in
createState.midiFiles rather than only index 0, passing each through the
existing editorShowAddKeysModal/_editorKeysHandleFile flow while preserving the
seeded arrangement handling.
- Around line 1878-1888: The _editorDoMidiCreate flow only forwards
createState.midiFiles[0], dropping additional staged MIDI files while the UI
claims they will be imported. Update _editorDoMidiCreate and the existing
keys-picker handoff to process every staged MIDI file, or constrain
editorContentImportSelected to stage only one file and keep the label consistent
with that limit.

In `@src/import.js`:
- Around line 300-308: Update the arrangement-renaming logic after the
arrangements normalization to run unconditionally, removing the
pickedList.length > 1 guard. Ensure every valid arrangement is paired with its
corresponding pickedList entry and renamed via _midiKeysArrNamePure, including
single-track imports.

---

Nitpick comments:
In `@routes.py`:
- Around line 5792-5847: Update _convert and its response handling so
_convert_one failures are isolated per selected track: catch each track’s
exception inside the batch loop, retain successful conversions, and collect
failed track identifiers and error details in a failed list. Return partial
results with the new failed field while preserving tempo_map generation and
successful track output; update the consuming frontend response handling to
accept and surface the changed response shape instead of returning a single 500
for one failed track.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 0e087663-c0f3-4310-b6c3-04beec267c47

📥 Commits

Reviewing files that changed from the base of the PR and between d7c5e3c and 24f983f.

📒 Files selected for processing (7)

• CHANGELOG.md
• routes.py
• src/create.js
• src/import.js
• src/main.js
• tests/create_gate.test.mjs
• tests/midi_create.test.mjs