fix(plot): reconnect orphaned jgd device on reattach

After a VS Code window reload, the JGD socket server starts on a new
socket path and the attach script updates JGD_SOCKET accordingly. But a
jgd device opened before the reload remains bound to the old, dead
socket: jgd::jgd() only reads JGD_SOCKET at device-creation time, so the
stale device never reconnects and subsequent plots silently render to
nowhere (reported by @renkun-ken for self-managed arf/tmux sessions).

In register_hooks(), when the jgd backend is active, detect an existing
jgd device, record its current plot, close it, and reopen jgd::jgd() so
it binds to the current socket — replaying the recorded plot so it
reappears after reload. No-ops when no jgd device is open.

Bump sess to 3.0.1 so the attach script reinstalls the corrected package
for sessions that already have 3.0.0.

Author: grantmcdermott

sess/DESCRIPTION

@@ -1,7 +1,7 @@
 Package: sess
 Type: Package
 Title: Modern R IPC Server
-Version: 3.0.0
+Version: 3.0.1
 Author: Gemini
 Maintainer: Gemini <gemini@example.com>
 Description: Implements a high-performance IPC client for R sessions using Unix domain sockets and Windows named pipes. Replaces legacy file-system watcher based workflows while keeping JSON-RPC communication semantics for IDE/editor integration.

sess/R/hooks.R

@@ -118,6 +118,27 @@ register_hooks <- function(use_rstudioapi = TRUE, use_httpgd = TRUE, use_jgd = F
     options(device = function(...) {
       jgd::jgd()
     })
+
+    # On reattach (e.g. after a VS Code window reload) the renderer starts a new
+    # socket, but any jgd device opened before the reload is still bound to the
+    # old, now-dead socket. jgd::jgd() only reads JGD_SOCKET at device-creation
+    # time, so the stale device never reconnects and plots silently go nowhere.
+    # Reopen it against the new socket, replaying the current plot if possible.
+    reconnect_jgd_device <- function() {
+      devs <- grDevices::dev.list()
+      if (is.null(devs) || !"jgd" %in% names(devs)) {
+        return(invisible(FALSE))
+      }
+      grDevices::dev.set(devs[names(devs) == "jgd"][[1]])
+      recorded <- tryCatch(grDevices::recordPlot(), error = function(e) NULL)
+      tryCatch(grDevices::dev.off(), error = function(e) NULL)
+      tryCatch(jgd::jgd(), error = function(e) NULL)
+      if (!is.null(recorded)) {
+        tryCatch(grDevices::replayPlot(recorded), error = function(e) NULL)
+      }
+      invisible(TRUE)
+    }
+    reconnect_jgd_device()
   } else if (use_httpgd && requireNamespace("httpgd", quietly = TRUE)) {
     options(device = function(...) {
       httpgd::hgd(silent = TRUE)