feat(tabs): drag-reorder + double-click rename + per-tab chat draft

- TabBar: HTML5 drag-and-drop to reorder user tabs (subagent tabs untouched);
  double-click a tab title to rename (Enter/blur confirm, Escape cancel).
- Store: add reorderTabs/renameTab/setDraft; per-tab in-memory `draft` and
  `manualTitle` fields. Manual rename suppresses first-message auto-title.
- ChatInput: bind to the active tab's draft so switching tabs saves/restores
  unsent text instead of clobbering it.
- Backend: updateTabPositions() + PATCH /tabs/reorder persist tab order to the
  existing `position` column; tabs without a stored position fall to the end
  then get explicit positions on first reorder.
- Tests: store reorder/rename/auto-title-guard/draft coverage; core
  updateTabPositions coverage (FakeDatabase extended with transaction support).

1 files changed, 13 insertions, 0 deletions

diff --git a/packages/api/src/routes/tabs.ts b/packages/api/src/routes/tabs.ts
index f52ee99..28a89f1 100644
--- a/packages/api/src/routes/tabs.ts
+++ b/packages/api/src/routes/tabs.ts
@@ -11,6 +11,7 @@ import {
 	listOpenTabs,
 	setSetting,
 	updateTabModel,
+	updateTabPositions,
 	updateTabStatus,
 	updateTabTitle,
 } from "@dispatch/core";
@@ -63,6 +64,18 @@ tabsRoutes.put("/settings/title-model", async (c) => {
 	return c.json({ success: true });
 });
 
+// Reorder open tabs. Body `{ ids }` is the new left-to-right order of tab ids;
+// each tab's `position` is rewritten to its index. Must be declared before the
+// `/:id` routes so "reorder" isn't captured as an id param.
+tabsRoutes.patch("/reorder", async (c) => {
+	const body = await c.req.json<{ ids?: string[] }>();
+	if (!Array.isArray(body.ids) || body.ids.some((id) => typeof id !== "string")) {
+		return c.json({ error: "ids must be an array of strings" }, 400);
+	}
+	updateTabPositions(body.ids);
+	return c.json({ success: true });
+});
+
 tabsRoutes.get("/:id", (c) => {
 	const id = c.req.param("id");
 	const tab = getTab(id);