spec: drums as arrangements — type:"drums" + per-arrangement drum_tab pointer (1.17.0)

[ChrisBeWithYou]

Drum charts become first-class arrangements, so a pack can carry more than one — two drummers recorded separately, a programmed layer beside an acoustic kit, or an aux-percussion part. Until now drums were a single song-level drum_tab sidecar, the one part that wasn't an arrangements[] entry.

The change

A drum part is now an arrangement entry with type: drums and a drum_tab pointer (no file, no notation) — mirroring how a keys part is an entry with a notation pointer. Additive MINOR (§4.2), fully back-compatible:

• Older Reader (no per-arrangement drum_tab): reads the one song-level drum_tab, treats each type: drums entry as a file-less arrangement it can't render → silently ignores the extras. Graceful degradation to one drummer, never an error.
• Newer Reader: takes its drum parts from the type: drums arrangements and MUST NOT also load the song-level key (it's the compat alias of the primary). No type: drums arrangements ⇒ the song-level drum_tab is the single drum part, unchanged.
• Single-drum packs are unchanged — Writers keep emitting only the song-level key.
• Normative: a type: drums arrangement MUST NOT be selected/scored as a pitched/fretted arrangement (it carries piece hits, not string·fret or notated pitch).

Lands together (§4.2)

• spec/feedpak-v1.md — §5.1 (drum_tab key now the primary/alias), §5.2 (the drums type value + a drum_tab arrangement field), §7.5 (new Multiple drum parts section with the reader/writer rules + the grading invariant), §4.1 version prose.
• schemas/manifest.schema.json — drum_tab on arrangementEntry + added to its file/notation anyOf (so a drums-only entry validates).
• examples/extended.feedpak — a primary Drums arrangement (aliasing the song-level drum_tab) + a second Drums (Live) with its own drum_tab_live.json.
• CHANGELOG.md, README + spec version → 1.17.0.
• Editorial drive-by: a pre-existing broken changelog anchor (#1-conventions → #1-conformance).

Checks (all pass locally)

check_versions.py · validate.py (both packs, dir and zip) · pytest (57) · mkdocs build --strict · ruff.

Coordination

• Version: concurrent with spec: MIDI-voiced sound sources — soundfont engine, source role, GM floor, tones binding (1.18.0) — FEP #61 #62 (also 1.17.0). Whichever lands second is a mechanical rebase to 1.18.0 (version strings + CHANGELOG heading + the §4.1 history sentence).
• Editor side: this is the "spec leads" step for the drums-as-arrangement work already open in feedback-plugin-editor (the editor already models drums as a type:"drums" session arrangement and keeps the song-level drum_tab as primary — this blesses that shape). Next: the core loader reads type: drums arrangements, then the editor's N-drums build path.
• Distinct from the still-in-discussion parts[] overlay — this is the focused, settled drums piece.

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features
  • Drum charts are now supported as first-class arrangements, enabling multiple drum parts within a feedpak.
  • Arrangements may reference per-arrangement drum chart data, with backward compatibility to the existing song-level drum chart.
  • Added a “Drums (Live)” example with timestamped hits.
• Documentation
  • Updated the spec and feedpak versioning to 1.17.0, including selection/compatibility rules.
  • Corrected a documentation cross-reference.
• Schema & Validation
  • Extended the manifest schema and validation to support optional per-arrangement drum_tab references.
• Tests
  • Added a regression test ensuring per-arrangement drum chart references are properly resolved and schema-validated.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: bef0c128-4de0-4cf7-84e5-5a3da4191a0f

📥 Commits

Reviewing files that changed from the base of the PR and between 0c32c75 and e68bc55.

📒 Files selected for processing (3)

• spec/feedpak-v1.md
• tests/test_validate.py
• tools/validate.py

🚧 Files skipped from review as they are similar to previous changes (1)

• spec/feedpak-v1.md

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📝 Walkthrough

Walkthrough

Feedpak 1.17.0 defines drum charts as first-class arrangements with per-arrangement drum_tab references, schema and validator support, compatibility behavior, selection constraints, examples, tests, and updated release metadata.

Changes

First-class drum arrangements

Layer / File(s)	Summary
Drum arrangement specification spec/feedpak-v1.md	Defines type: drums, per-arrangement drum_tab, song-level compatibility aliasing, chart references, and exclusion from pitched/fretted selection.
Schema and validation support schemas/manifest.schema.json, tools/validate.py, tests/test_validate.py	Allows drum_tab as an arrangement requirement, validates referenced chart files safely against the drum-tab schema, and tests invalid per-arrangement charts.
Example drum arrangements examples/extended.feedpak/manifest.yaml, examples/extended.feedpak/drum_tab_live.json	Adds primary and additional drum-chart arrangements with separate chart files and updates the example package version.
Version and changelog updates README.md, CHANGELOG.md	Updates displayed version references to 1.17.0, documents the drum arrangement change, and corrects an earlier cross-reference.

Estimated code review effort: 2 (Simple) | ~10 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Reader
  participant Manifest
  participant Validator
  participant DrumChart
  participant ArrangementSelector
  Reader->>Manifest: Read type: drums arrangements
  Manifest->>Validator: Resolve drum_tab references
  Validator->>DrumChart: Validate referenced JSON
  DrumChart-->>Validator: Return validation result
  Reader->>ArrangementSelector: Exclude drum arrangements from pitched/fretted selection

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Suggested reviewers: topkoa

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately highlights the main change: first-class drum arrangements with per-arrangement drum_tab support in spec 1.17.0.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fep/drums-as-arrangements

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