feat(lanes): record which CLI tool drives a lane

server/db.js

@@ -486,6 +486,22 @@ try {
   db.prepare("ALTER TABLE lanes ADD COLUMN slug TEXT").run();
 }
 
+// Migrate: which CLI drives this lane — `claude` (default) or `codex`. Additive
+// with a default, so every existing lane keeps today's behavior. A lane's tool
+// is immutable (never in PATCHABLE): the tmux pane, the run history and the
+// binary probe all key off it, so flipping it under a live pane would describe
+// a run that isn't what's actually attached.
+try {
+  db.prepare("SELECT tool FROM lanes LIMIT 1").get();
+} catch {
+  db.prepare("ALTER TABLE lanes ADD COLUMN tool TEXT NOT NULL DEFAULT 'claude'").run();
+}
+try {
+  db.prepare("SELECT tool FROM dashboard_runs LIMIT 1").get();
+} catch {
+  db.prepare("ALTER TABLE dashboard_runs ADD COLUMN tool TEXT NOT NULL DEFAULT 'claude'").run();
+}
+
 // Migrate: label a dashboard run with the lane it was started through, so the
 // Workspace page can show one lane's run history. Additive and nullable —
 // POST /api/run keeps writing rows with no lane. One probe for the one column.