feat(app): draggable tabs (#31364)

Co-authored-by: LukeParkerDev <10430890+Hona@users.noreply.github.com>

packages/app/src/utils/session-route.test.ts

@@ -1,8 +1,38 @@
 import { describe, expect, test } from "bun:test"
 import { ServerConnection } from "@/context/server"
-import { legacySessionHref, requireServerKey, rootSession, selectSessionLineage, sessionHref } from "./session-route"
+import {
+  legacySessionHref,
+  legacySessionServer,
+  requireServerKey,
+  rootSession,
+  selectSessionLineage,
+  sessionHref,
+} from "./session-route"
 
 describe("session routes", () => {
+  test("uses the unique persisted server for a legacy session route", () => {
+    expect(
+      legacySessionServer(
+        [{ type: "session", server: ServerConnection.Key.make("server-b"), sessionId: "session-1" }],
+        "session-1",
+        ServerConnection.Key.make("server-a"),
+      ),
+    ).toBe(ServerConnection.Key.make("server-b"))
+  })
+
+  test("prefers the active server when a legacy session ID is ambiguous", () => {
+    expect(
+      legacySessionServer(
+        [
+          { type: "session", server: ServerConnection.Key.make("server-a"), sessionId: "session-1" },
+          { type: "session", server: ServerConnection.Key.make("server-b"), sessionId: "session-1" },
+        ],
+        "session-1",
+        ServerConnection.Key.make("server-b"),
+      ),
+    ).toBe(ServerConnection.Key.make("server-b"))
+  })
+
   test("builds and decodes a server-keyed session route", () => {
     const server = ServerConnection.Key.make("https://example.com:4096")
     const href = sessionHref(server, "session-1")

packages/app/src/utils/session-route.ts

@@ -16,6 +16,15 @@ export function requireServerKey(segment: string | undefined) {
   return ServerConnection.Key.make(key)
 }
 
+export function legacySessionServer(
+  tabs: readonly { type: "session"; server: ServerConnection.Key; sessionId: string }[],
+  sessionID: string,
+  active: ServerConnection.Key,
+) {
+  const matches = tabs.filter((tab) => tab.sessionId === sessionID)
+  return matches.find((tab) => tab.server === active)?.server ?? (matches.length === 1 ? matches[0]?.server : active)
+}
+
 type SessionParent = { id: string; parentID?: string }
 
 export function selectSessionLineage<T extends { session: { id: string } }>(