feat(tui): allow backgrounding synchronous subagents (#30488)

packages/opencode/src/cli/cmd/run/runtime.ts

@@ -52,6 +52,7 @@ type RunRuntimeInput = {
   files: RunInput["files"]
   initialInput?: string
   thinking: boolean
+  backgroundSubagents: boolean
   replay?: boolean
   replayLimit?: number
   demo?: RunInput["demo"]
@@ -70,6 +71,7 @@ type RunLocalInput = {
   files: RunInput["files"]
   initialInput?: string
   thinking: boolean
+  backgroundSubagents: boolean
   replay?: boolean
   replayLimit?: number
   demo?: RunInput["demo"]
@@ -253,6 +255,7 @@ async function runInteractiveRuntime(input: RunRuntimeInput): Promise<void> {
         model: state.model,
         variant: state.activeVariant,
         tuiConfig,
+        backgroundSubagents: input.backgroundSubagents,
         onPermissionReply: async (next) => {
           if (state.demo?.permission(next)) {
             return
@@ -372,6 +375,10 @@ async function runInteractiveRuntime(input: RunRuntimeInput): Promise<void> {
               state.aborting = false
             })
         },
+        onBackground: () => {
+          if (!hasSession(input, state)) return
+          void ctx.sdk.experimental.session.background({ sessionID: state.sessionID }).catch(() => {})
+        },
         onSubagentSelect: (sessionID) => {
           state.selectSubagent?.(sessionID)
           log?.write("subagent.select", {
@@ -794,6 +801,7 @@ export async function runInteractiveLocalMode(input: RunLocalInput): Promise<voi
         files: input.files,
         initialInput: input.initialInput,
         thinking: input.thinking,
+        backgroundSubagents: input.backgroundSubagents,
         replay: input.replay,
         replayLimit: input.replayLimit,
         demo: input.demo,
@@ -848,6 +856,7 @@ export async function runInteractiveMode(input: RunInput & { createSession?: Cre
         files: input.files,
         initialInput: input.initialInput,
         thinking: input.thinking,
+        backgroundSubagents: input.backgroundSubagents,
         replay: input.replay,
         replayLimit: input.replayLimit,
         demo: input.demo,