feat(app): better subagent experience (#20708)

packages/app/src/pages/session/composer/session-composer-region.tsx

@@ -1,9 +1,11 @@
 import { Show, createEffect, createMemo, onCleanup } from "solid-js"
 import { createStore } from "solid-js/store"
+import { useNavigate } from "@solidjs/router"
 import { useSpring } from "@opencode-ai/ui/motion-spring"
 import { PromptInput } from "@/components/prompt-input"
 import { useLanguage } from "@/context/language"
 import { usePrompt } from "@/context/prompt"
+import { useSync } from "@/context/sync"
 import { getSessionHandoff, setSessionHandoff } from "@/pages/session/handoff"
 import { useSessionKey } from "@/pages/session/session-layout"
 import { SessionPermissionDock } from "@/pages/session/composer/session-permission-dock"
@@ -43,11 +45,17 @@ export function SessionComposerRegion(props: {
   }
   setPromptDockRef: (el: HTMLDivElement) => void
 }) {
+  const navigate = useNavigate()
   const prompt = usePrompt()
   const language = useLanguage()
   const route = useSessionKey()
+  const sync = useSync()
 
   const handoffPrompt = createMemo(() => getSessionHandoff(route.sessionKey())?.prompt)
+  const info = createMemo(() => (route.params.id ? sync.session.get(route.params.id) : undefined))
+  const parentID = createMemo(() => info()?.parentID)
+  const child = createMemo(() => !!parentID())
+  const showComposer = createMemo(() => !props.state.blocked() || child())
 
   const previewPrompt = () =>
     prompt
@@ -113,6 +121,12 @@ export function SessionComposerRegion(props: {
   const lift = createMemo(() => (rolled() ? 18 : 36 * value()))
   const full = createMemo(() => Math.max(78, store.height))
 
+  const openParent = () => {
+    const id = parentID()
+    if (!id) return
+    navigate(`/${route.params.dir}/session/${id}`)
+  }
+
   createEffect(() => {
     const el = store.body
     if (!el) return
@@ -156,7 +170,7 @@ export function SessionComposerRegion(props: {
           )}
         </Show>
 
-        <Show when={!props.state.blocked()}>
+        <Show when={showComposer()}>
           <Show
             when={prompt.ready()}
             fallback={
@@ -232,17 +246,40 @@ export function SessionComposerRegion(props: {
                   onEdit={props.followup!.onEdit}
                 />
               </Show>
-              <PromptInput
-                ref={props.inputRef}
-                newSessionWorktree={props.newSessionWorktree}
-                onNewSessionWorktreeReset={props.onNewSessionWorktreeReset}
-                edit={props.followup?.edit}
-                onEditLoaded={props.followup?.onEditLoaded}
-                shouldQueue={props.followup?.queue}
-                onQueue={props.followup?.onQueue}
-                onAbort={props.followup?.onAbort}
-                onSubmit={props.onSubmit}
-              />
+              <Show
+                when={child()}
+                fallback={
+                  <Show when={!props.state.blocked()}>
+                    <PromptInput
+                      ref={props.inputRef}
+                      newSessionWorktree={props.newSessionWorktree}
+                      onNewSessionWorktreeReset={props.onNewSessionWorktreeReset}
+                      edit={props.followup?.edit}
+                      onEditLoaded={props.followup?.onEditLoaded}
+                      shouldQueue={props.followup?.queue}
+                      onQueue={props.followup?.onQueue}
+                      onAbort={props.followup?.onAbort}
+                      onSubmit={props.onSubmit}
+                    />
+                  </Show>
+                }
+              >
+                <div
+                  ref={props.inputRef}
+                  class="w-full rounded-[12px] border border-border-weak-base bg-background-base p-3 text-16-regular text-text-weak"
+                >
+                  <span>{language.t("session.child.promptDisabled")} </span>
+                  <Show when={parentID()}>
+                    <button
+                      type="button"
+                      class="text-text-base transition-colors hover:text-text-strong"
+                      onClick={openParent}
+                    >
+                      {language.t("session.child.backToParent")}
+                    </button>
+                  </Show>
+                </div>
+              </Show>
             </div>
           </Show>
         </Show>