# Decision Record ## Decisions - Readiness is `L2 V5 build-packet candidate`; no build-ready language is used. - The design starts from real hurdy-gurdy mechanics: rosined wheel bow, crank, tangent keyboard, melody strings, drones, and trompette buzzing bridge. - The wheel is treated as the primary risk because trueness, rosin, string wrapping, and crank stability affect every voice. - The trompette bridge is treated as an adjustable experiment instead of a fixed part. - The keyboard is described as a serviceable tangent system; final key count, tangent spacing, and pitch layout are not claimed. - Every artifact in the visual register is marked `concept_only` or `pending_measurement`. - A cut-list scaffold was added as estimated blank families only, not released fabrication sizes. - Engineering review is organized around wheel/string friction, keybox repeatability, drone control, and trompette buzz controllability. ## Alternatives Considered - **Body-first design:** rejected for this uplift because body outline cannot validate wheel speech, tangent action, or trompette response by itself. - **Fixed trompette bridge:** rejected for L2; the bridge must stay adjustable until buzz onset and false chatter are tested. - **Hidden key action:** deferred because visible, serviceable tangents are easier to inspect during early setup. - **Full keyboard prototype first:** deferred in favor of a smaller wheel/string/tangent coupon that can isolate friction and return-action problems. - **Publishing estimated sizes:** rejected; all blank sizes remain `TBD` until measured or reviewed. ## Open Questions - What body outline, soundboard structure, and material stack should the first prototype use? - What wheel material and edge treatment can be trued repeatably in Tony's shop? - What bearing or bushing arrangement gives stable rotation while remaining serviceable around rosin dust? - How should tangents be adjusted and locked without making the keybox fragile? - How many melody, drone, and trompette strings should a first prototype carry? - What muting scheme makes drone testing tolerable during setup? - What trompette bridge adjustment range is needed for controllable buzz? - Which tests should happen on a wheel-and-string coupon before a full body is built? - What wheel runout, bearing backlash, key side play, and tangent repeatability should become measurable acceptance gates? - Which service operations must be possible without removing strings or the keybox? - How should rosin and string wrapping changes be logged so acoustic changes are not attributed to the wrong subsystem? ## Rejected For L2 - No final dimensions. - No tuning table. - No string gauges. - No CAD or DXF geometry. - No image or render authority. - No fabrication release claims. - No fabrication authority in the visual-output register.