diff --git a/docs/PLUGINS.md b/docs/PLUGINS.md
index 647a319f..12ddbdab 100644
--- a/docs/PLUGINS.md
+++ b/docs/PLUGINS.md
@@ -149,7 +149,7 @@ output goes to `client-build.log` next to it; the server's own output goes to
 |---|---|
 | `/ccam-doctor` | Node version, bootstrap state, runtime deps, server liveness, duplicate hooks, CLI launcher + PATH, MCP build freshness, UI bundle |
 | `/ccam-update` | Pull the latest `ccam` release via `claude plugin marketplace update` + `claude plugin update ccam@<marketplace> -y`, then reinstall dependencies and restart the server (`plugin-bootstrap.js --force`). The plugin pull needs a manual `/reload-plugins` afterward to take effect in the current session — not scriptable from a command. |
-| `/ccam-open` | Build the UI bundle if missing, then print the dashboard URL |
+| `/ccam-open` | Rebuild the UI bundle and print the dashboard URL. Re-runs the bootstrap first when the server is down or still executing a plugin root that a mid-session `/plugin` update retired, so a fresh bundle never talks to an older server's routes |
 
 ### Where things live
 
diff --git a/plugins/ccam/commands/ccam-open.md b/plugins/ccam/commands/ccam-open.md
index 82f00ada..6c24c4a6 100644
--- a/plugins/ccam/commands/ccam-open.md
+++ b/plugins/ccam/commands/ccam-open.md
@@ -12,8 +12,12 @@ node "${CLAUDE_PLUGIN_ROOT}/scripts/plugin-open.js" --force
 ```
 
 Install + build takes a few minutes if the client toolchain isn't already
-installed; otherwise the rebuild itself takes ~10-15s. No server restart is
-needed — the server already serves from that directory.
+installed; otherwise the rebuild itself takes ~10-15s. The server serves from
+that directory, so it usually needs no restart — but if it is down, or still
+running from a plugin root a mid-session `/plugin` update retired, the command
+re-runs bootstrap first and prints `Server restarted on the current plugin
+version.` (without it, the fresh bundle would call routes that old server
+never had).
 
 Then help the user open it:
 
diff --git a/scripts/plugin-open.js b/scripts/plugin-open.js
index 4c6176a6..3bf6af93 100644
--- a/scripts/plugin-open.js
+++ b/scripts/plugin-open.js
@@ -6,7 +6,10 @@
  * on session start, so client-only routes (e.g. `/run`) work the moment
  * `claude` is started, not just the API and MCP tools. `/ccam-open` re-runs
  * this standalone — a no-op when the bundle already matches — as a fallback
- * for `--force` rebuilds or a first build that failed during bootstrap.
+ * for `--force` rebuilds or a first build that failed during bootstrap, and it
+ * re-runs bootstrap first when the live server belongs to a retired plugin root
+ * (a mid-session `/plugin` update) so the new bundle is not left calling routes
+ * the running server never had.
  *
  * The client source is copied out of the (replaced-on-update) plugin cache into
  * the runtime dir before building, so neither the cache nor the checkout is
@@ -74,12 +77,21 @@ function dashboardUrl() {
 }
 
 if (require.main === module) {
+  // A plugin update applied mid-session (/plugin + /reload-plugins) fires no
+  // SessionStart, so the server keeps executing a cache dir Claude Code has
+  // already retired: a bundle rebuilt from the new root then calls routes that
+  // old server never had. Hand the version handover back to bootstrap, which
+  // owns stop/start and the dependency install the new root may need.
+  const stale = (boot.readState() || {}).pluginRoot !== PLUGIN_ROOT || !boot.serverIsLive();
+  if (stale) boot.bootstrap();
+
   const result = buildClient({ force: process.argv.includes("--force") });
   if (result === "failed") {
     console.error("Client build failed — the API and MCP tools still work.");
     process.exitCode = 1;
   } else {
     if (result === "built") console.log("Dashboard UI built.");
+    if (stale) console.log("Server restarted on the current plugin version.");
     console.log(dashboardUrl());
   }
 }