community: a proposal on your board arrives as a toast, carried sealed through the inbox

src-tauri/src/inbox.rs

@@ -52,6 +52,17 @@ pub enum Cargo {
     Share(ShareCargo),
     SpaceInvite(SpaceInvite),
     SpaceKey(SpaceKeyCargo),
+    ProposalPing(ProposalPing),
+}
+
+/// "Someone put a proposal on your playlist's board." Carries only enough to
+/// name it in a toast — the board itself stays the truth, and this is a
+/// best-effort nudge: the proposal stands whether or not the ping lands.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ProposalPing {
+    pub playlist_uuid: [u8; 16],
+    pub name: String,
+    pub proposal_id: [u8; 16],
 }
 
 /// "You are on the roster now, here is where the Space is" — and, for a
@@ -483,6 +494,7 @@ async fn dispatch(app: &tauri::AppHandle, sender: [u8; 32], cargo: Cargo) {
         Cargo::Share(s) => crate::shared_playlists::on_inbox_share(app, sender, s).await,
         Cargo::SpaceInvite(i) => crate::spaces::on_inbox_invite(app, sender, i).await,
         Cargo::SpaceKey(k) => crate::spaces::on_inbox_space_key(app, sender, k).await,
+        Cargo::ProposalPing(p) => crate::proposals::on_inbox_proposal(app, sender, p),
     }
 }
 
@@ -513,4 +525,44 @@ mod tests {
         assert_eq!(inbox.code_hash, "UjK4sLZqGSE2qEXwQYMvNFsTiuLSYjMJuwzVbhAtXKR");
         assert_eq!(desc.code_hash, "B4A2nMJgSKzgo72gaDJyTpFNTmjBynLFga3EiNoSVstv");
     }
+
+    /// The wire is the variant ORDER: bincode writes the index, so inserting a
+    /// variant renumbers every one after it and silently breaks every sealed
+    /// message already in flight. New cargo goes on the END, and this pins it.
+    #[test]
+    fn cargo_variant_indices_are_the_wire() {
+        let index = |c: &Cargo| {
+            let b = bincode::serialize(c).unwrap();
+            u32::from_le_bytes(b[..4].try_into().unwrap())
+        };
+        let share = Cargo::Share(ShareCargo {
+            owner: [1u8; 32],
+            playlist_uuid: [2u8; 16],
+            name: "n".into(),
+            entry_count: 1,
+        });
+        let key = Cargo::SpaceKey(SpaceKeyCargo {
+            space_id: [3u8; 16],
+            owner: [4u8; 32],
+            epoch: 9,
+            key: [5u8; 32],
+        });
+        let ping = Cargo::ProposalPing(ProposalPing {
+            playlist_uuid: [6u8; 16],
+            name: "Late Night Ambient".into(),
+            proposal_id: [7u8; 16],
+        });
+        assert_eq!(index(&share), 3, "Share moved — sealed shares in flight are now unreadable");
+        assert_eq!(index(&key), 5, "SpaceKey moved — sealed keys in flight are now unreadable");
+        assert_eq!(index(&ping), 6, "a new variant must be appended, never inserted");
+
+        let back: Cargo = bincode::deserialize(&bincode::serialize(&ping).unwrap()).unwrap();
+        match back {
+            Cargo::ProposalPing(p) => {
+                assert_eq!(p.name, "Late Night Ambient");
+                assert_eq!(p.proposal_id, [7u8; 16]);
+            }
+            other => panic!("round-tripped into {other:?}"),
+        }
+    }
 }