From dea6ccf58b8e68148497eb6160394a135c1a50fc Mon Sep 17 00:00:00 2001
From: Matt Silverlock <matt@eatsleeprepeat.net>
Date: Fri, 2 Jan 2026 13:36:01 -0500
Subject: [PATCH] fix: prevent subagent model changes from persisting to parent

---
 .../src/cli/cmd/tui/component/prompt/index.tsx        | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx b/packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx
index 1463c813e8a..08bfef03c84 100644
--- a/packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx
+++ b/packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx
@@ -130,6 +130,7 @@ export function Prompt(props: PromptProps) {
   })
 
   // Initialize agent/model/variant from last user message when session changes
+  // Skip syncing for subagent sessions to prevent model/agent bleed to parent
   let syncedSessionID: string | undefined
   createEffect(() => {
     const sessionID = props.sessionID
@@ -140,11 +141,11 @@ export function Prompt(props: PromptProps) {
 
       syncedSessionID = sessionID
 
-      // 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)
-      }
+      // Don't sync model/agent for subagent sessions (sessions with parentID)
+      const session = sync.data.session.find((s) => s.id === sessionID)
+      if (session?.parentID) return
+
+      if (msg.agent) local.agent.set(msg.agent)
       if (msg.model) local.model.set(msg.model)
       if (msg.variant) local.model.variant.set(msg.variant)
     }