printobserver-types.

Owns: the shared domain vocabulary every other crate speaks — printer and job identity, observed printer state, vision observations, supervisory decisions, and their serialized forms. It holds data and total functions over that data, never I/O.

May depend on: no crate of this workspace. It is the root of the graph, so a type it does not hold is a type the rest of the workspace cannot agree on.

One authoritative source per restated fact

The types here are declared once and imported by every consumer rather than re-declared. The JSON Schemas the clients and the agent's structured answer are validated against are generated from these types by the printobserver-types:schemas graph target, which the gate runs: a schema checked into schemas/ that no longer matches what these types generate fails that target. Nothing transcribes a schema by hand, and nothing restates a field.

[contract] is where that generation reads the declared set from: it is this crate's own claim about which types it declares and what a canonical value of each looks like.

The representations, stated once

• Identifiers. Every identifier this system mints is a UUID version 7, minted by the store, held as a distinct newtype per record, and serialized as its lowercase hyphenated string. See [ids].
• Numbers. Every temperature, factor, multiplier, percentage and fraction is a 64-bit float. Every byte count and every integer identifier an external system supplies is a 64-bit signed integer. Every duration is whole seconds as a 64-bit signed integer.
• Timestamps. Every timestamp is an instant in UTC, serialized as an RFC 3339 string with a zero offset. See [Timestamp].
• Optionality. An optional field absent means the source did not report it, and is never rendered as a zero, an empty string, or a default. Absent serializes as absent and parses back as absent.
• Declared ranges. A numeric field this crate declares a range for is typed [Reported<f64>]. See [reported] for the whole rule, including why a non-finite value is out of range and why one is refused on emission.

Why serde, schemars and serde_json are re-exported

The four port crates depend on this crate and on nothing else, and each of them declares request and answer shapes that cross a process boundary and so must derive the same traits these types derive. They reach the derive macros through [serde], [schemars] and [serde_json] here rather than by declaring a dependency of their own.