fix(fleet): enforce exact comms authority (#787)

packages/mosaic/framework/fleet/roster.schema.json

@@ -94,11 +94,11 @@
             "type": "string"
           },
           "ssh": {
-            "description": "SSH target (user@host) for a cross-host peer, so onboarding renders the `agent-send.sh -H <user@host>` form. Optional; only needed for agents on a different host than the fleet.",
+            "description": "Explicit SSH target (normally user@host) for a cross-host inventory peer. Exact comms rendering requires this whenever the peer's resolved host differs from the current agent's host; the host value is never substituted as an SSH destination.",
             "type": "string"
           },
           "socket": {
-            "description": "tmux socket the agent's session runs on. Onboarding renders `-L <socket>` when set; absent = the default socket (no `-L`). Must match the LIVE socket, not blindly inherit the roster's tmux.socket_name.",
+            "description": "Optional compatibility declaration of the fleet-wide tmux socket. When present it must exactly equal tmux.socket_name; independent per-agent sockets are rejected because the local fleet runtime provisions every session on the fleet-wide socket.",
             "type": "string"
           },
           "working_directory": {
@@ -150,29 +150,67 @@
       "description": "Orchestrator chat connector (F4). Optional — absent means tmux (back-compat). Secrets (access/bot tokens) come from the environment, never this file.",
       "type": "object",
       "additionalProperties": false,
-      "required": ["kind"],
-      "properties": {
-        "kind": {
-          "enum": ["tmux", "discord", "matrix"]
-        },
-        "matrix": {
-          "type": "object",
-          "additionalProperties": false,
-          "required": ["homeserver_url", "user_id", "room_id"],
-          "properties": {
-            "homeserver_url": { "type": "string" },
-            "user_id": { "type": "string" },
-            "room_id": { "type": "string" }
+      "oneOf": [
+        {
+          "properties": { "kind": { "const": "tmux" } },
+          "required": ["kind"],
+          "not": {
+            "anyOf": [{ "required": ["discord"] }, { "required": ["matrix"] }]
           }
         },
-        "discord": {
-          "type": "object",
-          "additionalProperties": false,
-          "required": ["channel_id"],
+        {
           "properties": {
-            "channel_id": { "type": "string" }
-          }
+            "kind": { "const": "discord" },
+            "discord": {
+              "type": "object",
+              "additionalProperties": false,
+              "required": ["channel_id"],
+              "properties": {
+                "channel_id": {
+                  "type": "string",
+                  "minLength": 1,
+                  "pattern": "\\S"
+                }
+              }
+            }
+          },
+          "required": ["kind", "discord"],
+          "not": { "required": ["matrix"] }
+        },
+        {
+          "properties": {
+            "kind": { "const": "matrix" },
+            "matrix": {
+              "type": "object",
+              "additionalProperties": false,
+              "required": ["homeserver_url", "user_id", "room_id"],
+              "properties": {
+                "homeserver_url": {
+                  "type": "string",
+                  "minLength": 1,
+                  "pattern": "\\S"
+                },
+                "user_id": {
+                  "type": "string",
+                  "minLength": 1,
+                  "pattern": "\\S"
+                },
+                "room_id": {
+                  "type": "string",
+                  "minLength": 1,
+                  "pattern": "\\S"
+                }
+              }
+            }
+          },
+          "required": ["kind", "matrix"],
+          "not": { "required": ["discord"] }
         }
+      ],
+      "properties": {
+        "kind": { "enum": ["tmux", "discord", "matrix"] },
+        "matrix": { "type": "object" },
+        "discord": { "type": "object" }
       }
     }
   }