adjust sessionid param desc

packages/app/e2e/regression/subagent-child-navigation.spec.ts

@@ -8,13 +8,10 @@ const directory = "C:/OpenCode/SubagentNavigation"
 const projectID = "proj_subagent_navigation"
 const parentID = "ses_subagent_parent"
 const childID = "ses_subagent_child"
-const grandchildID = "ses_subagent_grandchild"
 const parentTitle = "Parent session"
 const childTitle = "Subagent child session"
-const grandchildTitle = "Nested subagent session"
 // Child session pages derive their heading from the task part that spawned them.
 const taskDescription = "Inspect child navigation"
-const nestedTaskDescription = "Inspect nested navigation"
 
 test.use({ viewport: { width: 1440, height: 900 } })
 
@@ -29,23 +26,6 @@ test("navigates to a subagent child session missing from the session list", asyn
   await expect(titlebarRight.getByRole("button", { name: "Toggle review" })).toHaveCount(1)
 })
 
-test("keeps the root tab active for a nested subagent", async ({ page }) => {
-  await setup(page)
-  await openChildFromParent(page)
-  await expectSessionTitle(page, taskDescription)
-
-  const card = page.locator(`a[href="${sessionHref(grandchildID)}"]`)
-  await expect(card).toBeVisible()
-  await card.click()
-
-  await expect(page).toHaveURL(new RegExp(`/server/.+/session/${grandchildID}$`), { timeout: 15_000 })
-  await expectSessionTitle(page, nestedTaskDescription)
-
-  const rootTab = page.locator(`[data-titlebar-tab-slot]:has(a[href="${sessionHref(parentID)}"])`)
-  await expect(rootTab).toHaveAttribute("data-active", "true")
-  await expect(page.locator("[data-titlebar-tab-slot]:visible")).toHaveCount(1)
-})
-
 test("keeps the parent visible while the child session resolves", async ({ page }) => {
   await setup(page)
   const requested = Promise.withResolvers<void>()
@@ -114,10 +94,8 @@ async function setup(page: Page, events?: () => OpenCodeEvent[]) {
       connected: ["opencode"],
       default: { providerID: "opencode", modelID: "claude-opus-4-6" },
     },
-    sessions: [session(parentID, parentTitle, 1700000000000), childSession(), grandchildSession()],
-    pageMessages: (sessionID) => ({
-      items: sessionID === parentID ? parentMessages() : sessionID === childID ? childMessages() : [],
-    }),
+    sessions: [session(parentID, parentTitle, 1700000000000), childSession()],
+    pageMessages: (sessionID) => ({ items: sessionID === parentID ? parentMessages() : [] }),
     events,
     eventRetry: events ? 16 : undefined,
   })
@@ -167,10 +145,6 @@ function childSession() {
   return session(childID, childTitle, 1700000001000, { parentID })
 }
 
-function grandchildSession() {
-  return session(grandchildID, grandchildTitle, 1700000002000, { parentID: childID })
-}
-
 function parentMessages(): SessionMessageInfo[] {
   const userID = "msg_user_0001"
   const assistantID = "msg_assistant_0001"
@@ -208,43 +182,6 @@ function parentMessages(): SessionMessageInfo[] {
   ]
 }
 
-function childMessages(): SessionMessageInfo[] {
-  const userID = "msg_user_0002"
-  const assistantID = "msg_assistant_0002"
-  return [
-    {
-      id: userID,
-      type: "user",
-      time: { created: 1700000002000 },
-      text: "Delegate nested work to a subagent",
-    },
-    {
-      id: assistantID,
-      type: "assistant",
-      time: { created: 1700000003000, completed: 1700000004000 },
-      model: { id: "claude-opus-4-6", providerID: "opencode" },
-      agent: "build",
-      cost: 0.01,
-      tokens: { input: 100, output: 200, reasoning: 0, cache: { read: 0, write: 0 } },
-      finish: "stop",
-      content: [
-        {
-          type: "tool",
-          id: "call_subagent_0002",
-          name: "subagent",
-          time: { created: 1700000003000, ran: 1700000003000, completed: 1700000004000 },
-          state: {
-            status: "completed",
-            input: { description: nestedTaskDescription, agent: "explore", prompt: "Inspect the nested work." },
-            content: [{ type: "text", text: "Nested subagent finished" }],
-            metadata: { sessionID: grandchildID },
-          },
-        },
-      ],
-    },
-  ]
-}
-
 async function configurePage(page: Page) {
   const server = `http://${process.env.PLAYWRIGHT_SERVER_HOST ?? "127.0.0.1"}:${process.env.PLAYWRIGHT_SERVER_PORT ?? "4096"}`
   await page.addInitScript(

packages/app/src/components/titlebar.tsx

@@ -34,7 +34,6 @@ import { tabKey, useTabs } from "@/context/tabs"
 import type { PromptSession } from "@/context/prompt"
 import "./titlebar.css"
 import { newTabTooltipKeybind } from "./command-tooltip-keybind"
-import { rootSession } from "@/utils/session-route"
 
 const v2TitlebarHeight = 36
 const minTitlebarZoom = 0.25
@@ -171,43 +170,15 @@ export function Titlebar(props: { update?: TitlebarUpdate; debugTools?: { visibl
             const tabs = useTabs()
             const tabsStore = tabs.store
             const tabsStoreActions = tabs
-            const routeContext = createMemo(() => {
-              const route = layout.route()
-              if (route.type !== "session") return
-              const conn = global.servers.list().find((item) => ServerConnection.key(item) === route.server)
-              return conn ? { route, ctx: global.ensureServerCtx(conn) } : undefined
-            })
-            const [resolvedSession] = createResource(routeContext, ({ route, ctx }) =>
-              (async () => {
-                const session =
-                  ctx.data.session.get(route.sessionId) ??
-                  (await ctx.sdk.api.session.get({ sessionID: route.sessionId }))
-                const root = await rootSession(
-                  session,
-                  async (sessionID) =>
-                    ctx.data.session.get(sessionID) ?? (await ctx.sdk.api.session.get({ sessionID })),
-                )
-                return { session, rootID: root.id }
-              })().catch(() => undefined),
+            const [session] = createResource(
+              () => {
+                const route = layout.route()
+                if (route.type !== "session") return undefined
+                const conn = global.servers.list().find((item) => ServerConnection.key(item) === route.server)
+                return conn ? { route, sdk: global.ensureServerCtx(conn).sdk } : undefined
+              },
+              ({ route, sdk }) => sdk.api.session.get({ sessionID: route.sessionId }).catch(() => {}),
             )
-            const session = () => {
-              const input = routeContext()
-              if (!input) return
-              const loaded = input.ctx.data.session.get(input.route.sessionId)
-              if (loaded) return loaded
-              const resolved = resolvedSession()
-              return resolved?.session.id === input.route.sessionId ? resolved.session : undefined
-            }
-            const rootID = () => {
-              const input = routeContext()
-              if (!input) return
-              const current = input.ctx.data.session.get(input.route.sessionId)
-              const resolved = resolvedSession()
-              if (!current) return resolved?.session.id === input.route.sessionId ? resolved.rootID : undefined
-              const root = input.ctx.data.session.root(current.id)
-              if (!current.parentID || input.ctx.data.session.get(root)) return root
-              return resolved?.session.id === input.route.sessionId ? resolved.rootID : undefined
-            }
 
             const matchRoute = (route: LayoutRoute) => {
               if (route.type === "home") return
@@ -215,10 +186,19 @@ export function Titlebar(props: { update?: TitlebarUpdate; debugTools?: { visibl
                 return tabsStore.find((item) => item.type === "draft" && item.draftID === route.draftID)
               }
               if (route.type === "session") {
-                const sessionId = rootID() ?? route.sessionId
-                return tabsStore.find(
-                  (item) => item.type === "session" && item.server === route.server && item.sessionId === sessionId,
+                const main = tabsStore.find(
+                  (item) =>
+                    item.type === "session" && item.server === route.server && item.sessionId === route.sessionId,
                 )
+                if (main) return main
+                const s = session()
+                if (s?.parentID) {
+                  const parentID = s.parentID
+                  const parent = tabsStore.find(
+                    (item) => item.type === "session" && item.server === route.server && item.sessionId === parentID,
+                  )
+                  if (parent) return parent
+                }
               }
             }
 
@@ -234,8 +214,9 @@ export function Titlebar(props: { update?: TitlebarUpdate; debugTools?: { visibl
               }
 
               if (route.type === "session") {
-                const sessionId = rootID()
-                if (!sessionId) return
+                const s = session()
+                if (!s) return
+                const sessionId = s.parentID ?? s.id
                 const next = { server: route.server, sessionId }
                 tabsStoreActions.addSessionTab(next)
               }

packages/core/src/tool/plugin/subagent.ts

@@ -25,7 +25,7 @@ export const Input = Schema.Struct({
   prompt: Schema.String.annotate({ description: "The task for the subagent to perform" }),
   sessionID: Schema.optionalKey(SessionSchema.ID).annotate({
     description:
-      "Continue a specific previous subagent conversation by passing its sessionID. Calls without a sessionID start a new conversation.",
+      "Optional. To continue a previous child, pass the sessionID returned by its earlier subagent call. To start a new child, omit this field. Never pass the current session ID or invent an ID.",
   }),
   background: Schema.optionalKey(Schema.Boolean).annotate({
     description:
@@ -40,7 +40,8 @@ export const Output = Schema.Struct({
 })
 export const description = [
   "Spawns an agent in a child session to work on the specified task.",
-  "The output includes a sessionID you can pass back later to continue that specific conversation with the subagent.",
+  "To start a new child, omit sessionID. To continue a previous child, pass the sessionID returned by its earlier subagent call.",
+  "Never pass the current session ID or invent an ID.",
   "New child sessions start with fresh context, so include all relevant context and instructions when you don't pass a sessionID.",
   "Foreground (default) runs the subagent to completion and returns its final response.",
   "Background mode (background=true) launches it asynchronously and returns immediately; you are notified when it finishes.",