ReadonlyidReadonlysourcesStored the way a session stores a channel's sources: a stagebox leg names the BOX and the input on it, anything else names its port (import('./patch-identity.js')). The two documents share the shape deliberately — a standalone patch and a session must not disagree about what an endpoint means.
Optional ReadonlystereoThe channel's semantic source width at capture: true when the patch made the
channel stereo (a stereo pair was patched in — isStereoEndpoint). Stored
explicitly rather than re-derived from the endpoints on load because provenance
matters: a construction-seeded engine feed is 2-channel plumbing (mono by the
surface's convention), while the same-shaped pair patched by the operator is a
stereo source. Absent on files predating the field — the loader falls back to
deriving from the endpoint shapes (isStereoPatch).
One channel's input patch: the ordered set of source endpoints feeding its head,
[primary, ...extras]. More than one entry means several inputs sum at the head (the crosspoint patchbay's multi-in). Always at least one entry (else the channel is omitted).