Dirge lenses

/hive <lens> [args] resolves an open lens registry; /hive lens lists it. A lens contributes {:lens/id :lens/title :lens/panel :lens/open :lens/verbs :lens/keys :lens/cursor?}. :lens/open receives [ports config ctx] and returns {:fx [show-panel-ops] :text chat-summary}. A verb receives [ports row-id payload]. Its show-panel carries :keys (lowercase dirge chords, with either a reply verb or {"invoke" "verb"}) and :cursor true. For a row-oriented doc, :panel/rows holds id-bearing lines alongside the ordinary vessel doc; the dirge-specific JSON translator preserves their ids and payloads inside lines. The panel id is the stable invoke routing key.

An IAddon exposes :dirge/lenses (a collection or zero-arg function) in its hooks map and :dirge/invoke (fn of {:panel :verb :row :payload} returning truthy if handled). The host collects these contributions, routes only verbs registered for the owning panel and calls the owning addon's hook. The hive addon also exposes :dirge/register-lenses! to overlay lenses at runtime; no other addon has to edit hive-dirge core. For a mount-time contribution, provide :dirge/lenses in the addon manifest capabilities so the host mounts after it. The discovery doc publishes capabilities v1 with replies, derived invokes and key hints; each panel's keys remain authoritative when chords collide across lenses. The five Olympus reply actions are unchanged.

An addon that presents into dirge through hive.dirge.host (rather than as a lens of hive.dirge) owns its panel from the outside: the host's hooks :vessel/register-panel-verbs! (fn of panel verbs, where VERBS maps a verb string to (fn [invoke])) and :vessel/unregister-panel-verbs! (fn of panel) register the verbs an invoke reply on that panel runs. A lens-owned panel still routes to its owner first; an unregistered verb is ignored with a warning. Registrations live as long as the host instance, so a presenter re-offers them after a host restart.

Feature handshake (Lens C3)

dirge subscribes with GET /vessel/events?token=..&vessel=dirge&features=spans,keys,cursor,open-file. hive-vessel (commit d7fda1a, branch lens-c3-features) parses the comma list per client and records the set; hive-dirge's host reads it back and answers it as :vessel/features on the :vessel/target hook. The feature set is versioned at 1 (hive-dirge.host.domain/feature-set-version, the mirror of hive-vessel.executor.handshake/feature-set-version); bump only for a breaking change to the features param semantics.

Union semantics. The target advertises the union of the connected dirge clients' sets: a feature is present when any client advertised it. Every consumer of :vessel/features gates on that union: the dirge show-panel translator ships spans, keys and cursor whenever the union contains them. The union is the capability-projection policy -- a feature a client never advertised must not degrade the clients that did (and unknown fields are ignored by clients without that feature). Plain lines always carry row ids, so invoke routing works on any client.

• :spans — structured span rows appear inside "lines", never as a top-level "spans" field; without it lines flatten to text while retaining row ids and payloads.
• :keys — the message carries "keys" (dirge chords) when the panel declares them.
• open-file — reserved for the open-file feed op.

deps.edn still pins hive-vessel 0.1.12, whose bridge does not record features: the reader resolves hive-vessel.executor.sse/client-features at call time and degrades to #{} (plain lines), so this repo loads and runs green against either side.