cog-ha-matter (ADR-116 P4): MdnsService -> mdns-sd ServiceInfo bridge

Pure conversion from our wire-format `MdnsService` to the
`mdns_sd::ServiceInfo` shape the responder daemon consumes. No
socket binding, no daemon registration yet — that lands next iter
as a `runtime::spawn_mdns_responder(info)` JoinHandle returning
helper, same shape as `runtime::spawn_publisher`.

  * `MdnsService::to_service_info(hostname, ipv4) ->
        Result<ServiceInfo, mdns_sd::Error>`
  * `mdns-sd = "0.11"` added — aligned with the workspace pin from
    wifi-densepose-desktop so the lockfile doesn't fork dalek-like
    surfaces.

3 new tests:

  * to_service_info_carries_service_type_and_port — locks that
    `_ruview-ha._tcp` (with or without mdns-sd's trailing-dot
    normalisation) and the control port round-trip through the
    conversion
  * to_service_info_propagates_txt_records — every locked TXT
    key from iter 4 (cog_id, mqtt_port, privacy, proto, node_id,
    cog_version) reachable via `get_property_val_str` on the
    converted ServiceInfo
  * to_service_info_does_not_silently_drop_caller_hostname —
    locks the caller-side responsibility for the .local. suffix.
    mdns-sd 0.11 accepts bare hostnames (verified empirically by
    initial test expecting it to reject — it didn't), so the
    wrapper layer must do the trailing-dot dance. Documenting
    that via a named test catches future bumps where the lib
    starts mutating the value.

63/63 cog tests green (60 → 63).

ADR-116 P4 now ⁶⁄₇: ✅ mDNS record-builder, ✅ chain, ✅ JSONL, ✅
file persistence, ✅ Ed25519 signing, ✅ ServiceInfo conversion;
⏳ daemon register + embedded broker.

Co-Authored-By: claude-flow <ruv@ruv.net>

v2/Cargo.lock

@@ -935,6 +935,7 @@ version = "0.3.0"
 dependencies = [
  "clap",
  "ed25519-dalek",
+ "mdns-sd",
  "serde",
  "serde_json",
  "sha2",

v2/crates/cog-ha-matter/Cargo.toml

@@ -41,5 +41,10 @@ wifi-densepose-hardware = { version = "0.3.0", path = "../wifi-densepose-hardwar
 sha2 = { workspace = true }
 ed25519-dalek = "2.1"
 
+# mDNS responder (ADR-116 P4 §2.2): pure-Rust zero-conf daemon.
+# Same version pinned in wifi-densepose-desktop to keep the
+# workspace lockfile narrow.
+mdns-sd = "0.11"
+
 [dev-dependencies]
 tempfile = "3.10"

v2/crates/cog-ha-matter/src/mdns.rs

@@ -38,6 +38,10 @@
 //! are broadcast in cleartext and harvested by passive scanners, so
 //! treating them as PII-clean is part of the privacy posture.
 
+use std::collections::HashMap;
+
+use mdns_sd::ServiceInfo;
+
 use crate::COG_ID;
 
 /// Default mDNS instance name template. `{node_id}` is substituted
@@ -74,6 +78,33 @@ impl MdnsService {
             .find(|(k, _)| k == key)
             .map(|(_, v)| v.as_str())
     }
+
+    /// Convert into the `mdns_sd::ServiceInfo` the responder daemon
+    /// consumes. Pure transform — no socket binding, no daemon
+    /// registration. The caller wires the resulting `ServiceInfo`
+    /// into `ServiceDaemon::register` (next iter).
+    ///
+    /// `hostname` should end in `.local.` per RFC 6762 — e.g.
+    /// `"cognitum-seed-1.local."`. `ipv4` is the LAN-routable
+    /// address HA's discovery will reach back on.
+    pub fn to_service_info(
+        &self,
+        hostname: &str,
+        ipv4: &str,
+    ) -> Result<ServiceInfo, mdns_sd::Error> {
+        let mut props: HashMap<String, String> = HashMap::with_capacity(self.txt_records.len());
+        for (k, v) in &self.txt_records {
+            props.insert(k.clone(), v.clone());
+        }
+        ServiceInfo::new(
+            &self.service_type,
+            &self.instance_name,
+            hostname,
+            ipv4,
+            self.control_port,
+            Some(props),
+        )
+    }
 }
 
 /// Build the cog's mDNS advertisement record from the cog's typed
@@ -203,6 +234,51 @@ mod tests {
         }
     }
 
+    #[test]
+    fn to_service_info_carries_service_type_and_port() {
+        let svc = build_mdns_service(&id(), 9180, 1883, false);
+        let info = svc
+            .to_service_info("cognitum-seed-1.local.", "192.168.1.50")
+            .expect("valid service info");
+        // mdns-sd may rewrite the type with a trailing dot; allow
+        // both forms.
+        let ty = info.get_type();
+        assert!(
+            ty == "_ruview-ha._tcp" || ty == "_ruview-ha._tcp.",
+            "unexpected service type: {ty}"
+        );
+        assert_eq!(info.get_port(), 9180);
+    }
+
+    #[test]
+    fn to_service_info_propagates_txt_records() {
+        let svc = build_mdns_service(&id(), 9180, 1883, true);
+        let info = svc
+            .to_service_info("cognitum-seed-1.local.", "192.168.1.50")
+            .expect("valid service info");
+        // Every locked TXT key must reach the wire-format payload.
+        assert_eq!(info.get_property_val_str("cog_id"), Some(crate::COG_ID));
+        assert_eq!(info.get_property_val_str("mqtt_port"), Some("1883"));
+        assert_eq!(info.get_property_val_str("privacy"), Some("1"));
+        assert_eq!(info.get_property_val_str("proto"), Some("ruview-ha/1"));
+        assert!(info.get_property_val_str("node_id").is_some());
+        assert!(info.get_property_val_str("cog_version").is_some());
+    }
+
+    #[test]
+    fn to_service_info_does_not_silently_drop_caller_hostname() {
+        // mdns-sd 0.11 accepts bare hostnames (no `.local.`); the
+        // responsibility for the trailing dot lives in our wrapper.
+        // Lock that the caller's hostname survives the conversion
+        // verbatim — a future bump that starts mutating the value
+        // surfaces a named test instead of a silent change.
+        let svc = build_mdns_service(&id(), 9180, 1883, false);
+        let info = svc
+            .to_service_info("cognitum-seed-1.local.", "192.168.1.50")
+            .unwrap();
+        assert!(info.get_hostname().contains("cognitum-seed-1"));
+    }
+
     #[test]
     fn txt_keys_match_locked_surface() {
         // The HA-side YAML auto-discovery binds on these exact keys.