fix(desktop): narrow MCP discovery permissions

- Limit text reads and existence checks to platform discovery files
- Drop unused create and open capabilities
- Document restored desktop automation reconnection

CHANGELOG.md

@@ -58,6 +58,7 @@
 
 ### Fixed
 
+- Reconnect desktop automation to an already-running MCP server by allowing access to its discovery file. (#546)
 - Keep text-editing carets, hit testing, and selection highlights aligned with vertically centered or bottom-aligned text. (#539)
 - Match AI chat code-block syntax colors and backgrounds to the active light or dark theme. (#537)
 - Let desktop users select and copy AI chat text without replacing it with the selected canvas layers. (#538)

desktop/capabilities/default.json

@@ -20,7 +20,12 @@
     },
     {
       "identifier": "fs:allow-read-text-file",
-      "allow": [{ "path": "**" }]
+      "allow": [
+        { "path": "$HOME/Library/Application Support/OpenPencil/mcp.json" },
+        { "path": "$LOCALDATA/OpenPencil/mcp.json" },
+        { "path": "$RUNTIME/openpencil/mcp.json" },
+        { "path": "$HOME/.openpencil/mcp.json" }
+      ]
     },
     {
       "identifier": "fs:allow-write-file",
@@ -28,15 +33,12 @@
     },
     {
       "identifier": "fs:allow-exists",
-      "allow": [{ "path": "**" }]
-    },
-    {
-      "identifier": "fs:allow-create",
-      "allow": [{ "path": "**" }]
-    },
-    {
-      "identifier": "fs:allow-open",
-      "allow": [{ "path": "**" }]
+      "allow": [
+        { "path": "$HOME/Library/Application Support/OpenPencil/mcp.json" },
+        { "path": "$LOCALDATA/OpenPencil/mcp.json" },
+        { "path": "$RUNTIME/openpencil/mcp.json" },
+        { "path": "$HOME/.openpencil/mcp.json" }
+      ]
     },
     {
       "identifier": "fs:allow-mkdir",