feat(#1007): select-as-action — picking a parent directly triggers M0V3

Selecting any option in the M0V3 dropdown now fires confirm+POST
immediately; no separate button needed. On cancel or after the
request completes, the select resets to the placeholder. Removes
the now-redundant btn-move button and its CSS rule.

frontend/packages/dashboard/src/dashboard.css

@@ -2520,6 +2520,4 @@ body.dashboard-shell.has-selection { padding-bottom: 4.5em; }
   opacity: 0.5;
   cursor: default;
 }
-.move-picker .btn-move {
+
-  margin-left: 0;
-}

frontend/packages/dashboard/src/tabs.js

@@ -933,33 +933,24 @@ window.marked = marked;
       disabledTitle: why('PURG3', managerNames.map((n) => `\`${n}\` is the manager`)),
     });
 
-    // Move agent(s) in the topology tree — see
+    // Move agent(s) in the topology tree — selecting an option in the
-    // docs/web-ui.md::Selection bar for the two affordances:
+    // M0V3 dropdown immediately confirms + executes the move. "(no parent)"
+    // promotes to root (empty new_parent on the backend). Cycle-safe:
+    // dropdown filters out self and descendants on the client side; the
+    // backend rechecks via `topology::set_parent`.
     //
-    //   ⇡ M0V3 → ROOT   promote selected agent(s) to top-level (parent=null)
+    // Backend: POST /api/topology/set-parent (dashboard.rs),
-    //   ⇢ M0V3 → [sel]  reparent the single selected agent under a picked
+    // form-encoded `child=<name>&new_parent=<target-or-empty>`. Re-emits
-    //                   parent (cycle-safe — the dropdown filters out self
+    // container snapshots on success so the tree repaints without a
-    //                   and own descendants on the client side; the
+    // separate refresh.
-    //                   backend rechecks via `topology::set_parent`).
-    //
-    // Backend lives at POST /api/topology/set-parent (dashboard.rs),
-    // form-encoded `child=<name>&new_parent=<target-or-empty>`. The
-    // backend re-emits container snapshots on success, so the tree
-    // repaints without a separate refresh.
     addMoveActions(actions, selected, containers);
   }
 
-  // Render the M0V3 affordances inside the selection bar — separate
+  // Render the M0V3 picker in the selection bar. Selecting any real option
-  // helper because the picker variant needs a select + button pair,
+  // (including "(no parent)") immediately fires a confirm + POST — no
-  // not the single-button shape addBulkButton ships. Backend
+  // separate button. Backend `topology::set_parent` refuses invalid moves
-  // `topology::set_parent` refuses moves it can't satisfy (manager
+  // and the refusal surfaces in the alert roll-up.
-  // included) and the refusal surfaces in the bulk-action error
-  // roll-up.
   function addMoveActions(parent, selected, containers) {
-    // Unified M0V3 picker: a single `<select>` with "(no parent)" as the
-    // first real choice (backend: empty new_parent → promotes to root) plus
-    // all valid candidate agents. Removes the need for a separate ROOT
-    // button — picking "(no parent)" achieves the same outcome.
     const candidates = validReparentCandidates(selected, containers);
     const wrap = el('span', { class: 'move-picker' });
     const selectTitle = selected.length === 1
@@ -967,28 +958,24 @@ window.marked = marked;
       : `change ${selected.length} agents' parent`;
     const sel = el('select', { class: 'move-picker-select', title: selectTitle });
     sel.append(el('option', { value: '' }, '⇢ M0V3 →'));
-    // "(no parent)" promotes selected agent(s) to top-level.
+    // "(no parent)" → empty new_parent on the backend (promotes to root).
     sel.append(el('option', { value: '__root__' }, '(no parent)'));
     for (const name of candidates) {
       sel.append(el('option', { value: name }, name));
     }
-    const btn = el('button', { type: 'button', class: 'btn btn-move' }, 'M0V3');
+    sel.addEventListener('change', async () => {
-    btn.disabled = true;
-    // Enable once any real choice is made (selectedIndex > 0).
-    sel.addEventListener('change', () => { btn.disabled = sel.selectedIndex === 0; });
-    btn.addEventListener('click', async () => {
       if (sel.selectedIndex === 0) return;
-      // '__root__' → empty new_parent (promotes to root / no parent).
       const newParent = sel.value === '__root__' ? '' : sel.value;
       const newParentLabel = sel.value === '__root__' ? '(no parent)' : sel.value;
       const names = selected.map((c) => c.name);
       const promptMsg = names.length === 1
         ? `move ${names[0]} → ${newParentLabel}?`
         : `move ${names.length} agents (${names.join(', ')}) → ${newParentLabel}?`;
-      if (!confirm(promptMsg)) return;
+      if (!confirm(promptMsg)) {
-      btn.disabled = true;
+        sel.selectedIndex = 0;
-      const original = btn.textContent;
+        return;
-      btn.innerHTML = '<span class="spinner">◐</span>';
+      }
+      sel.disabled = true;
       const failures = [];
       for (const name of names) {
         try {
@@ -1009,13 +996,13 @@ window.marked = marked;
           failures.push(`${name}: ${err}`);
         }
       }
-      btn.textContent = original;
+      sel.disabled = false;
-      btn.disabled = sel.selectedIndex === 0;
+      sel.selectedIndex = 0;
       if (failures.length) {
         alert(`M0V3 completed with ${failures.length} failure${failures.length === 1 ? '' : 's'}:\n\n` + failures.join('\n'));
       }
     });
-    wrap.append(sel, btn);
+    wrap.append(sel);
     parent.append(wrap);
   }