cosmix-lib-props-core — property read surface

cosmix-lib-props-core is the pure-type half of the SPEC 07 property surface. It defines how a daemon exposes a typed, dotted property tree without pulling in storage, hooks, audit, or the SPEC 12 mutation router.

The default feature set has no Bus dependency. Enable bus only when a consumer needs wire dispatch or publication-message builders.

What it is

The three central types are:

PropPath — a validated dotted path. Segments contain lowercase ASCII letters, digits, or _; empty segments and * are rejected.
PropValue — the serialisable value set: null, bool, signed i64, unsigned u64, f64, string, list, or deterministically ordered object.
PropTree — the trait a property producer implements with snapshot, list, and describe.

PropTree supplies default get and redacted_snapshot implementations. get walks the object snapshot by path. Redaction consults each PropDescribe.sensitive flag and replaces sensitive leaves with the type-appropriate redacted value.

PropDescribe and PropType describe the schema for a leaf or subtree. The crate also exports diff, redact, tree::build_snapshot, and the lightweight in-memory revisioned-write types under revwrite.

The SPEC 07 read surface

With the bus feature enabled, bus::dispatch_props maps the suffixes get, list, and describe onto a &dyn PropTree:

get returns the full snapshot or the value at args.path;
list returns every leaf path; and
describe returns the schema entry for the required args.path.

It returns a PropsResponse containing rc, body, and optional error text. bus::build_response turns that result into a BusMessage, setting type=response, service and requester addresses, command, and return code. Routing and transport remain the daemon's responsibility.

Publication helpers

The bus feature also exposes publish:

world_topic(svc) produces the retained world.<svc> snapshot topic.
props_changed_topic(svc) produces <svc>.props.changed.
build_world_message serialises a property snapshot into a BusMessage.
build_props_changed_message builds the per-leaf {path, old, new, ts, cause} event and matching filter headers.

The builders return inner BusMessage values. The caller chooses the transport, topic wrapper, retention policy, and trigger.

SPEC 07 and SPEC 12

This crate owns the common read contract. The cos repo's cosmix-lib-props-store pairs it with the substrate side:

namespace specifications and lifecycle;
persistent and in-memory storage backends;
mutation hooks, capability checks, and the SPEC 12 mutation router; and
audit and per-record integrity machinery.

Keeping that split means a consumer can parse paths, values, descriptions, and read replies without acquiring storage or daemon dependencies.

Features

Feature	What it adds
default	Pure property types, schema helpers, redaction, diff, and revisioned in-memory write helpers.
`bus`	`bus::{dispatch_props, build_response, PropsResponse}` plus `publish::*`; pulls `cosmix-lib-bus` and `chrono`.