fix(tui): Don't overwrite the agent that was specified on the command line (#20554)

Author: CarloWood

packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx

@@ -37,6 +37,7 @@ import { useToast } from "../../ui/toast"
 import { useKV } from "../../context/kv"
 import { useTextareaKeybindings } from "../textarea-keybindings"
 import { DialogSkill } from "../dialog-skill"
+import { useArgs } from "@tui/context/args"
 
 export type PromptProps = {
   sessionID?: string
@@ -81,6 +82,7 @@ export function Prompt(props: PromptProps) {
 
   const keybind = useKeybind()
   const local = useLocal()
+  const args = useArgs()
   const sdk = useSDK()
   const route = useRoute()
   const sync = useSync()
@@ -202,7 +204,8 @@ export function Prompt(props: PromptProps) {
       // Only set agent if it's a primary agent (not a subagent)
       const isPrimaryAgent = local.agent.list().some((x) => x.name === msg.agent)
       if (msg.agent && isPrimaryAgent) {
-        local.agent.set(msg.agent)
+        // Keep command line --agent if specified.
+        if (!args.agent) local.agent.set(msg.agent)
         if (msg.model) {
           local.model.set(msg.model)
           local.model.variant.set(msg.model.variant)