The Oboe's A: A Parable of the Declared Key

A pedagogical parable illustrating the Declared Key proposal for latent-space interoperability. Forty strangers arrive with one page of music each; nothing sounds together until the head of the line declares the frame and the oboe gives the A. The parable maps onto the formal treatment: the keycard = declared reference-frame metadata shipped with a checkpoint; clef = axes; key = orientation; metre = declared grouping; the metronome mark = declared metric and value; "Trumpet in B flat" = the per-model declared transform; the oboe's A = anchor witnesses checked at use time, with the parts untouched; the fiddler who needs no page = relative representations; two bands tuning to one A = orthogonal Procrustes alignment W = UV^T from anchor correspondences; "arranged for the salon" = the declared validity domain and the measured cross-domain penalty. Companion to the formal paper "The Declared Key: Shipping Latent Reference Frames as Checkpoint Metadata" (doi:10.5281/zenodo.23843513).