diff --git a/docs/web-ui.md b/docs/web-ui.md
index ec734dfd..a4a39df6 100644
--- a/docs/web-ui.md
+++ b/docs/web-ui.md
@@ -440,6 +440,16 @@ frosted-mauve bar slides up from the bottom of the viewport
   - `▶ ST4RT` — stopped agents only
   - `↻ R3BU1LD` — always available
   - `DESTR0Y` / `PURG3` — sub-agents only (disabled if manager selected)
+  - `⇡ M0V3 → ROOT` (#486) — promote selected agents to top-level
+    (parent = null); disabled when all selected are already at root
+    or when the selection includes the manager.
+  - `⇢ M0V3 → [select]` (#486) — single-agent-only inline picker;
+    the dropdown lists every container that isn't the target itself
+    nor a descendant of it (client-side cycle prevention; the
+    backend's `topology::set_parent` re-checks). On submit POSTs to
+    `/api/topology/set-parent` (form-encoded `child=<name>&new_parent=<target>`),
+    which writes `topology.json` and re-emits a container snapshot so
+    the tree repaints without a page reload.
 - **`✕ clear`** button + `Esc` key clear the entire selection.
 
 Stale selections (agents destroyed while selected) are pruned on
diff --git a/frontend/packages/dashboard/src/dashboard.css b/frontend/packages/dashboard/src/dashboard.css
index 08150b4a..20260a0e 100644
--- a/frontend/packages/dashboard/src/dashboard.css
+++ b/frontend/packages/dashboard/src/dashboard.css
@@ -915,6 +915,11 @@ ul form.inline { display: inline-block; }
 .btn-restart { color: var(--cyan); border-color: var(--cyan); font-size: 0.75em; padding: 0.15em 0.5em; margin-left: 0.6em; }
 .btn-stop    { color: var(--pink); border-color: var(--pink); font-size: 0.75em; padding: 0.15em 0.5em; margin-left: 0.6em; }
 .btn-start   { color: var(--green); border-color: var(--green); font-size: 0.75em; padding: 0.15em 0.5em; margin-left: 0.6em; }
+/* #486 — M0V3 affordance (selection bar). Mauve picks up the same
+   accent the question-override / mid-status surfaces use; reads as
+   "structural change" rather than the destructive red / amber chrome
+   of destroy / rebuild. */
+.btn-move    { color: var(--mauve); border-color: var(--mauve); font-size: 0.75em; padding: 0.15em 0.5em; margin-left: 0.6em; }
 .btn-talk { color: var(--cyan); border-color: var(--cyan); }
 .btn-spawn { color: var(--amber); border-color: var(--amber); }
 .btn-fire-now { color: var(--mauve, #cba6f7); border-color: var(--mauve, #cba6f7); }
@@ -2085,3 +2090,32 @@ body.flow-shell .tabbar .tab.active.tab-link {
    visible (`body.has-selection`, toggled by tabs.js when the
    selection set is non-empty). */
 body.dashboard-shell.has-selection { padding-bottom: 4.5em; }
+
+/* #486 — M0V3 → <pick> picker. Inline `<select>` + button pair
+   sitting alongside the bulk action buttons in the selection bar.
+   The select inherits the terminal-y monospace look so it doesn't
+   read as system-chrome popping out of the swarm aesthetic. Only
+   surfaces when exactly one agent is selected. */
+.move-picker {
+  display: inline-flex;
+  align-items: center;
+  gap: 0.3em;
+  margin-left: 0.6em;
+}
+.move-picker-select {
+  font-family: inherit;
+  font-size: 0.75em;
+  background: var(--bg);
+  color: var(--fg);
+  border: 1px solid var(--mauve);
+  border-radius: 2px;
+  padding: 0.1em 0.3em;
+  max-width: 16em;
+}
+.move-picker-select:disabled {
+  opacity: 0.5;
+  cursor: default;
+}
+.move-picker .btn-move {
+  margin-left: 0;
+}
diff --git a/frontend/packages/dashboard/src/tabs.js b/frontend/packages/dashboard/src/tabs.js
index 3881123e..b06791c8 100644
--- a/frontend/packages/dashboard/src/tabs.js
+++ b/frontend/packages/dashboard/src/tabs.js
@@ -864,6 +864,134 @@ window.marked = marked;
       confirm: (names) => `PURGE ${names.length} agent${names.length === 1 ? '' : 's'} (${names.join(', ')})? containers, config history, claude creds, and notes are all WIPED. no undo.`,
       disabledTitle: why('PURG3', managerNames.map((n) => `\`${n}\` is the manager`)),
     });
+
+    // #486 — move agent(s) in the topology tree. Two affordances:
+    //
+    //   ⇡ M0V3 → ROOT   promote selected agent(s) to top-level (parent=null)
+    //   ⇢ M0V3 → [sel]  reparent the single selected agent under a picked
+    //                   parent (cycle-safe — the dropdown filters out self
+    //                   and own descendants on the client side; the
+    //                   backend rechecks via `topology::set_parent`).
+    //
+    // Backend lives at POST /api/topology/set-parent (dashboard.rs#2170),
+    // 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);
+  }
+
+  // #486 — render the M0V3 affordances inside the selection bar. Split
+  // into its own helper because the picker variant needs a select + button
+  // pair, not the single-button shape addBulkButton ships.
+  function addMoveActions(parent, selected, containers) {
+    // Manager can never be a child of anything — backend refuses with
+    // "refusing to move the manager". Disable both affordances when the
+    // selection includes hm1nd (or any agent flagged is_manager).
+    const managerNames = selected.filter((c) => c.is_manager).map((c) => c.name);
+    const movable = !managerNames.length;
+
+    // M0V3 → ROOT: parent=null for every selected agent. Only meaningful
+    // when at least one selected agent currently has a non-null parent;
+    // otherwise it's a no-op for everything.
+    const someNotAtRoot = selected.some((c) => c.parent);
+    addBulkButton(parent, 'btn-move', '⇡ M0V3 → ROOT', movable && someNotAtRoot, selected, {
+      action: '/api/topology/set-parent',
+      perAgentBodyFor: (name) => ({ child: name, new_parent: '' }),
+      confirm: (names) => `promote ${names.length} agent${names.length === 1 ? '' : 's'} (${names.join(', ')}) to top-level (parent → root)?`,
+      disabledTitle: !movable
+        ? why('⇡ M0V3 → ROOT', managerNames.map((n) => `\`${n}\` is the manager`))
+        : (!someNotAtRoot ? '⇡ M0V3 → ROOT not available — all selected agents are already at root' : null),
+    });
+
+    // M0V3 → <pick>: only when exactly one agent is selected. Picker
+    // omits self + own descendants (cycle-safe) + the manager (the
+    // backend allows manager-as-parent, that's fine — manager IS the
+    // default parent already, so we include it as an option). Empty
+    // candidate list ⇒ disable the picker.
+    if (selected.length !== 1 || !movable) {
+      // Multi-select or manager-included → skip the picker. The
+      // ROOT button above still applies; the picker is single-agent
+      // ergonomics only.
+      return;
+    }
+    const target = selected[0];
+    const candidates = validReparentCandidates(target, containers);
+
+    const wrap = el('span', { class: 'move-picker' });
+    const select = el('select', {
+      class: 'move-picker-select',
+      title: `change ${target.name}'s parent`,
+    });
+    select.append(el('option', { value: '' }, '— pick parent —'));
+    for (const name of candidates) {
+      select.append(el('option', { value: name }, name));
+    }
+    if (!candidates.length) {
+      select.disabled = true;
+      select.title = `no valid parents for ${target.name} (all other agents are its descendants)`;
+    }
+    const btn = el('button', { type: 'button', class: 'btn btn-move' }, '⇢ M0V3');
+    btn.disabled = true;
+    select.addEventListener('change', () => { btn.disabled = !select.value; });
+    btn.addEventListener('click', async () => {
+      const newParent = select.value;
+      if (!newParent) return;
+      if (!confirm(`move ${target.name} under ${newParent}?`)) return;
+      btn.disabled = true;
+      const original = btn.innerHTML;
+      btn.innerHTML = '<span class="spinner">◐</span> ⇢ M0V3';
+      try {
+        const body = new URLSearchParams({ child: target.name, new_parent: newParent });
+        const resp = await fetch('/api/topology/set-parent', {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
+          body,
+          redirect: 'manual',
+        });
+        const ok = resp.ok || resp.type === 'opaqueredirect'
+          || (resp.status >= 200 && resp.status < 400);
+        if (!ok) {
+          const text = await resp.text().catch(() => '');
+          alert(`move failed: http ${resp.status}${text ? ' — ' + text.slice(0, 200) : ''}`);
+        }
+      } catch (err) {
+        alert(`move failed: ${err}`);
+      }
+      btn.innerHTML = original;
+      btn.disabled = !select.value;
+    });
+    wrap.append(select, btn);
+    parent.append(wrap);
+  }
+
+  // Filter the dashboard's container list to those that are valid
+  // re-parent targets for `target`: anyone who isn't `target` itself,
+  // isn't a descendant of `target` (cycle prevention), and isn't a
+  // tombstoned/non-running entry that the topology layer would refuse.
+  // The backend re-checks the same constraints; this client-side filter
+  // is purely UX so the operator can't pick an obviously-invalid option.
+  function validReparentCandidates(target, containers) {
+    // Build descendant set for target via BFS through the parent map.
+    const childrenOf = new Map();
+    for (const c of containers) {
+      const p = c.parent || null;
+      if (!childrenOf.has(p)) childrenOf.set(p, []);
+      childrenOf.get(p).push(c.name);
+    }
+    const descendants = new Set([target.name]);
+    const queue = [target.name];
+    while (queue.length) {
+      const n = queue.shift();
+      for (const child of (childrenOf.get(n) || [])) {
+        if (descendants.has(child)) continue;
+        descendants.add(child);
+        queue.push(child);
+      }
+    }
+    return containers
+      .filter((c) => !descendants.has(c.name))
+      .map((c) => c.name)
+      .sort();
   }
 
   function addBulkButton(parent, btnClass, label, enabled, selected, opts) {
@@ -887,10 +1015,25 @@ window.marked = marked;
       // Sequential POSTs to keep server-side serialisation predictable
       // (rebuild_queue dedups but other endpoints don't); the loop is
       // short — bulk selections are typically a handful of agents.
+      //
+      // Two URL shapes:
+      //  - `opts.action` is a path prefix and the agent name gets
+      //    appended (lifecycle endpoints: /start/<name>, /rebuild/<name>).
+      //    `opts.body` is a static object applied to every POST.
+      //  - `opts.perAgentBodyFor(name)` is set: `opts.action` is the
+      //    full URL (no name appended) and the per-agent body comes
+      //    from the callback. Used by /api/topology/set-parent (#486),
+      //    where the agent name is a body field rather than a URL
+      //    component.
       for (const name of names) {
-        const body = new URLSearchParams(opts.body || {});
+        const body = opts.perAgentBodyFor
+          ? new URLSearchParams(opts.perAgentBodyFor(name))
+          : new URLSearchParams(opts.body || {});
+        const url = opts.perAgentBodyFor
+          ? opts.action
+          : opts.action + encodeURIComponent(name);
         try {
-          const resp = await fetch(opts.action + encodeURIComponent(name), {
+          const resp = await fetch(url, {
             method: 'POST',
             headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
             body,