# Demonstrated capabilities and limits

| Behavior | Active implementation | Evidence |
|---|---|---|
| New tune without a compulsory head rhythm | Source-independent action construction | Empty-head and held-head synthetic tests |
| Arpeggiated expansion / scalar route / neighbor motion | Complete contextual pitch route | Operation reachability and route tests |
| Development, answer, return, optional head reference | Heard-theme/source feature used only by the selected action | Each action requested and realized in eligible authored contexts |
| Open continuation / local settling / completion / handoff | Different timing and destination contracts | Candidate diversity and terminal-hold tests |
| Rest, pickup, syncopation, cross-bar group, tuplet | Exact rhythm groups and complete authored cells | Group, notation and playback tests |
| Early destination, approach, enclosure, connection | Joint proposals and existing typed validation | Positive/negative contract tests and final expression reports |
| Stable/resolving colors, prepared suspension, blues | General chord/function policy; complete realized evidence | Retained validator tests and construction coverage |
| All six strings; no open strings; frets 1–12 | Shared pitch domain and complete-melody placement | Physical tests and published TAB validation |
| No target dependency / no other generated-role dependency | Input audit and independent role cache | Dependency checks and full-song document hashes |

Not every enabled treatment must be selected in every song. Rejections and selected uses are separate from capability. A failed bounded search is not a proof that a musical solution is impossible.

The source melody is optional material, not a compulsory blueprint. A return currently preserves the rhythm and direction of a short heard signature with harmonic adaptation; this is weaker than requiring its exact intervals. This can still be perceptually insufficient. Phrase-level context and the user's listening assessment remain important.

The route solver selects a complete path but internally uses a bounded pitch frontier. It does not perform a global whole-chorus optimum or arbitrary two-sided rewriting of committed phrases. One-phrase lookahead chooses a different complete alternative instead. Faster passages use a coarse tempo policy; legal TAB is not proof of human comfort.

Unsupported written chords still produce explicit mapper errors. No missing initial harmony is invented. Source-defined vocal protection remains authoritative even when a comparison reference continues beyond it. No new dynamics, swing, accents, velocities or timbral effects were introduced.