feat: auto-derive technique tags from notation in curation

[PhysShell]

Why

Guitar Pro import already records techniques explicitly (ADR-0018), yet curation
left ChunkMeta.techniques empty and asked a human to re-tag by hand what the
tab already states. This is the first step of corpus-curation automation: read
the techniques for free.

What

New griff_core::technique:

• derive_techniques(score, track) — scans the track's primary voice
  (voice 0) — the same convention structure/gesture/boundaries follow —
  and returns the techniques the notation states are present:
  • tags: the SwancoreTags with a dedicated per-occurrence variant —
    hammer-on, pull-off, slide, bend, vibrato, palm-mute, natural/artificial
    harmonic;
  • names: the superset of lower_snake_case technique names, also
    recording legato, accent, ghost, staccato, dead-note and tap (which have no
    dedicated tag).
• merge_tags(chosen, derived) — keeps the curator's order, then appends
  any derived tag not already present. Stable and idempotent, so auto-derivation
  adds technique tags without overriding the curator's choices.

Wired into both chunk-assembly seams — CLI griff curate
(build_chunk_meta) and the web capture tool (build_chunk_meta_record):
techniques is now populated and the tags are the union of the curator's picks
and the derived set. The emitted chunk.json stays byte-compatible with what
griff manifest reads.

Deliberately out of scope

Presence-only — no thresholds or heuristics — so it stays a pure function of the
score (SPEC §6). The passage-level tags TappingPassage / LegatoPassage are
about dominance, not presence, so they are intentionally not derived here
(a single legato slur is not a legato passage). Candidate for a follow-up.

Tests (strict TDD)

• 298aea9 red → 719557e green for derive_techniques; the green step also
  pins the voice-0 convention (a technique in a secondary voice is not derived),
  caught from the CLI's primary_voice_note_count tests.
• core/tests/technique_tags.rs: mapping, dedupe/determinism, primary-voice,
  merge_tags order + idempotency.
• CLI + web wiring each get a test that a techniques-bearing track auto-fills
  techniques and merges tags while keeping the curator's hand-picked tag.

Validation

• core 90 unit + 5 technique_tags; cli unit (incl. new wiring test) +
  curate_cmd 10 unchanged; web 17/17 host tests.
• cargo clippy --workspace --all-targets -- -D warnings (incl. nursery)
  clean; web crate clippy clean; wasm32-unknown-unknown release build green.

🤖 Generated with Claude Code

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Generated by Claude Code

Summary by CodeRabbit

• New Features
  • Auto-detect techniques from Guitar Pro notation during chunk curation
  • Automatically populate chunk techniques based on notation spans and note marks
  • Preserve curator-selected tags while merging with auto-detected technique tags
• Tests
  • Added unit tests covering technique derivation, deterministic ordering, deduplication, out-of-range behavior, and tag merge idempotency

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 14311d3f-dee4-4daa-ab00-21069ec35bb6

📥 Commits

Reviewing files that changed from the base of the PR and between eec7e70 and d52a7cb.

📒 Files selected for processing (2)

• core/src/technique.rs
• core/tests/technique_tags.rs

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

• core/src/technique.rs

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📝 Walkthrough

Walkthrough

Adds a new core/src/technique.rs module exposing DerivedTechniques, derive_techniques, and merge_tags. Both the CLI (build_chunk_meta) and web (build_chunk_meta_record) chunk curation paths now call this module to auto-populate ChunkMeta.techniques and merge derived technique tags with curator-chosen tags.

Changes

Technique auto-derivation into ChunkMeta

Layer / File(s)	Summary
Core technique module: struct, mappings, and functions core/src/lib.rs, core/src/technique.rs	Registers pub mod technique, defines DerivedTechniques { tags, names }, adds canonical SpanTechnique/NoteMark-to-SwancoreTag mapping helpers, implements derive_techniques (multi-voice scan with ordered deduplication), and implements merge_tags (stable union appending only missing derived tags).
Core technique tests core/tests/technique_tags.rs	Adds score_with minimal score builder and five test cases: span-to-tag mapping with names superset, determinism/deduplication, empty/out-of-range track default, merge_tags order preservation and idempotence, secondary-voice-only technique detection.
CLI and web integration cli/src/main.rs, web/src/lib.rs	Both entry points import technique, call derive_techniques for the selected track, merge derived tags with curator-chosen tags via merge_tags, and set ChunkMeta.techniques from derived names instead of an empty list; integration tests are added for both.

Sequence Diagram(s)

sequenceDiagram
  participant Curator
  participant build_chunk_meta
  participant derive_techniques
  participant merge_tags
  participant ChunkMeta

  Curator->>build_chunk_meta: inputs (track_index, chosen_tag_indices, score)
  build_chunk_meta->>derive_techniques: (score, track_index)
  derive_techniques-->>build_chunk_meta: DerivedTechniques {tags, names}
  build_chunk_meta->>merge_tags: (chosen_tags, derived.tags)
  merge_tags-->>build_chunk_meta: merged Vec<SwancoreTag>
  build_chunk_meta->>ChunkMeta: techniques = derived.names, tags = merged
  ChunkMeta-->>Curator: populated ChunkMeta record

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• PhysShell/griff#51: Updates the GP importer to emit additional TechniqueSpans (e.g., Bend) and NoteMark variants (e.g., DeadNote), which directly extends the set of techniques that derive_techniques can detect and auto-populate into ChunkMeta.techniques.
• PhysShell/griff#67: The retrieved PR introduces build_chunk_json for the chunk.json flow in web/src/lib.rs, while this PR updates the metadata-building checkpoint (build_chunk_meta_record) that both paths share to auto-derive techniques and merge technique tags.

Poem

🐰 Hop, hop, through the staff I go,
Hammer-ons and harmonics in a row,
Each span I sniff, each mark I find,
No technique left for me behind!
The ChunkMeta blooms with names galore—
One happy rabbit, tagging more! 🎸

🚥 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 PR title 'feat: auto-derive technique tags from notation in curation' directly and clearly summarizes the main change: automatic derivation of technique tags from Guitar Pro notation during curation.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

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✨ Finishing Touches

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• Commit unit tests in branch claude/auto-technique-tags

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[PhysShell]

@codex review

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Generated by Claude Code

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: eec7e70109

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[PhysShell]

@codex review

Addressed the P2 — derive_techniques now scans all voices (d52a7cb), matching track_notes/technique_share (structure + complexity.technical), so the techniques/tags metadata can no longer disagree with the technical metric. Same voice-handling call reached in #38. Good catch. 🙏

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Generated by Claude Code

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Bravo.

Reviewed commit: d52a7cb2cc

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• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

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Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".