picker-registry

Direction: guest calls into the host through it · Capability: none (pure data / dispatch) · Worlds: picker-source-plugin (imports), project-plugin (imports)

OR.5b — the host import a picker plugin registers its sources through. Each registered source is then served by the plugin's picker-source export.

Why this is an import and not an export. Before OR.5b the seam was shaped "the component IS one picker source": it exported spec(), and the host registered exactly one source per component. That made picker-source the only contribution seam in the system shaped that way — language, grammar, config, modes, theme, help and keymap are all "the guest calls a host import to register N things" — and the exception was not free. Org needs three pickers (refile, roam find-node, roam insert-node) and could register one.

So this matches the rest: the host calls register-picker-sources once, the guest calls register-picker-source for each, and init / accept take the source id so one actor serves them all.

Uses

• picker-source-spec from types

Functions (1)

register-picker-source

register-picker-source: func(spec: picker-source-spec)

Declare one picker source. Called from the guest's register-picker-sources export; the host registers each into the same PickerRegistry a first-party source lives in.

A second registration under an id this plugin already used replaces it — a plugin reload, not a collision. Two DIFFERENT plugins claiming one id is resolved the way the registry has always resolved it: last write wins, and the teardown token unregisters by id.

Example — Register two picker sources from one component, each with a full spec · crates/lattice-plugin-host/tests/fixtures/picker-guest/src/lib.rs

fn register_picker_sources() {
    register_picker_source(&PickerSourceSpec {
        id: FIXTURE.to_string(),
        doc: "PH7.4c.1b fixture picker source".to_string(),
        args_schema: Vec::new(),
        args_hint: "[fail]".to_string(),
        live: false,
        // OR.5: the source declares that it can create what the query
        // names. `%s` is replaced by the query when the row renders.
        create_label: Some("Create fixture: %s".to_string()),
        // PP.2: `true` on purpose. The field's failure mode is a boundary
        // arm that writes the default, which a fixture declaring `false`
        // cannot tell apart from one that carries the value — the hole
        // PC.11's `fill-action` shipped through.
        rooted: true,
        // PD.1, same reasoning as `rooted` above and the same hole it
        // guards: a boundary arm writing `None` is indistinguishable from
        // one that carried a `None`, so this source names a command and
        // its sibling names none.
        delete_command: Some("fixture-forget".to_string()),
    });
    register_picker_source(&PickerSourceSpec {
        id: SECOND.to_string(),
        doc: "OR.5b: a SECOND source from the same component".to_string(),
        args_schema: Vec::new(),
        args_hint: String::new(),
        live: false,
        create_label: None,
        // …and `false` here, so the pair proves the value TRAVELS rather
        // than that the host defaults everything to the same answer.
        rooted: false,
        delete_command: None,
    });
}