fix(app): keep terminal mounted when switching session tabs in a workspace

packages/app/test-browser/session-route-boundary.test.ts

@@ -0,0 +1,85 @@
+import { expect, test } from "bun:test"
+import { createComponent, createSignal, onCleanup } from "solid-js"
+import { render } from "solid-js/web"
+import { SessionRouteBoundary } from "@/pages/session/route-boundary"
+
+// Terminals (and other workspace-scoped state) live inside the route subtree,
+// so switching session tabs within the same server must not remount it.
+test("switching sessions on the same server does not remount the route subtree", () => {
+  const [server, setServer] = createSignal("srv_1")
+  const [session, setSession] = createSignal("ses_a")
+  let mounts = 0
+  let disposals = 0
+  const Probe = () => {
+    mounts += 1
+    onCleanup(() => {
+      disposals += 1
+    })
+    return null
+  }
+
+  const dispose = render(
+    () =>
+      createComponent(SessionRouteBoundary, {
+        get serverKey() {
+          return server()
+        },
+        get sessionID() {
+          return session()
+        },
+        fallback: () => null,
+        get children() {
+          return createComponent(Probe, {})
+        },
+      }),
+    document.createElement("div"),
+  )
+
+  const initialMounts = mounts
+  expect(initialMounts).toBeGreaterThan(0)
+
+  setSession("ses_b")
+  expect(mounts).toBe(initialMounts)
+  expect(disposals).toBe(0)
+
+  setServer("srv_2")
+  expect(mounts).toBeGreaterThan(initialMounts)
+  expect(disposals).toBeGreaterThan(0)
+
+  dispose()
+})
+
+// Without a per-session remount, the error boundary must clear a stale error
+// (e.g. session not found) when navigating to a different session.
+test("route error clears when navigating to a different session", () => {
+  const [session, setSession] = createSignal("ses_a")
+  const [broken, setBroken] = createSignal(true)
+  const Thrower = () => {
+    if (broken()) throw new Error(`Session not found: ${session()}`)
+    return "content"
+  }
+
+  const container = document.createElement("div")
+  const dispose = render(
+    () =>
+      createComponent(SessionRouteBoundary, {
+        serverKey: "srv_1",
+        get sessionID() {
+          return session()
+        },
+        fallback: () => "error-fallback",
+        get children() {
+          return createComponent(Thrower, {})
+        },
+      }),
+    container,
+  )
+
+  expect(container.textContent).toBe("error-fallback")
+
+  setBroken(false)
+  setSession("ses_b")
+  expect(container.textContent).toBe("content")
+
+  dispose()
+})