fix(opencode): keep user message variants scoped to model (#21332)

5 files changed, 12 insertions, 14 deletions

diff --git a/packages/app/src/components/prompt-input/submit.test.ts b/packages/app/src/components/prompt-input/submit.test.ts
index b0166c43a..03bece2e3 100644
--- a/packages/app/src/components/prompt-input/submit.test.ts
+++ b/packages/app/src/components/prompt-input/submit.test.ts
@@ -146,7 +146,7 @@ beforeAll(async () => {
           add: (value: {
             directory?: string
             sessionID?: string
-            message: { agent: string; model: { providerID: string; modelID: string }; variant?: string }
+            message: { agent: string; model: { providerID: string; modelID: string; variant?: string } }
           }) => {
             optimistic.push(value)
             optimisticSeeded.push(
@@ -310,8 +310,7 @@ describe("prompt submit worktree selection", () => {
     expect(optimistic[0]).toMatchObject({
       message: {
         agent: "agent",
-        model: { providerID: "provider", modelID: "model" },
-        variant: "high",
+        model: { providerID: "provider", modelID: "model", variant: "high" },
       },
     })
   })
diff --git a/packages/app/src/components/prompt-input/submit.ts b/packages/app/src/components/prompt-input/submit.ts
index 06b6c1e35..2a3a3d0e9 100644
--- a/packages/app/src/components/prompt-input/submit.ts
+++ b/packages/app/src/components/prompt-input/submit.ts
@@ -121,8 +121,7 @@ export async function sendFollowupDraft(input: FollowupSendInput) {
     role: "user",
     time: { created: Date.now() },
     agent: input.draft.agent,
-    model: input.draft.model,
-    variant: input.draft.variant,
+    model: { ...input.draft.model, variant: input.draft.variant },
   }
 
   const add = () =>
diff --git a/packages/app/src/context/local.tsx b/packages/app/src/context/local.tsx
index 84a613c0d..1633607de 100644
--- a/packages/app/src/context/local.tsx
+++ b/packages/app/src/context/local.tsx
@@ -11,7 +11,7 @@ import { cycleModelVariant, getConfiguredAgentVariant, resolveModelVariant } fro
 import { useSDK } from "./sdk"
 import { useSync } from "./sync"
 
-export type ModelKey = { providerID: string; modelID: string }
+export type ModelKey = { providerID: string; modelID: string; variant?: string }
 
 type State = {
   agent?: string
@@ -373,7 +373,7 @@ export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
           handoff.set(handoffKey(dir, session), next)
           setStore("draft", undefined)
         },
-        restore(msg: { sessionID: string; agent: string; model: ModelKey; variant?: string }) {
+        restore(msg: { sessionID: string; agent: string; model: ModelKey }) {
           const session = id()
           if (!session) return
           if (msg.sessionID !== session) return
@@ -383,7 +383,7 @@ export const { use: useLocal, provider: LocalProvider } = createSimpleContext({
           setSaved("session", session, {
             agent: msg.agent,
             model: msg.model,
-            variant: msg.variant ?? null,
+            variant: msg.model.variant ?? null,
           })
         },
       },
diff --git a/packages/app/src/context/sync.tsx b/packages/app/src/context/sync.tsx
index bbf4fc5ec..b023e8ddc 100644
--- a/packages/app/src/context/sync.tsx
+++ b/packages/app/src/context/sync.tsx
@@ -416,8 +416,7 @@ export const { use: useSync, provider: SyncProvider } = createSimpleContext({
             role: "user",
             time: { created: Date.now() },
             agent: input.agent,
-            model: input.model,
-            variant: input.variant,
+            model: { ...input.model, variant: input.variant },
           }
           const [, setStore] = target()
           setOptimistic(sdk.directory, input.sessionID, { message, parts: input.parts })
diff --git a/packages/app/src/pages/session/session-model-helpers.test.ts b/packages/app/src/pages/session/session-model-helpers.test.ts
index 319db805d..2ab293b8f 100644
--- a/packages/app/src/pages/session/session-model-helpers.test.ts
+++ b/packages/app/src/pages/session/session-model-helpers.test.ts
@@ -2,7 +2,7 @@ import { describe, expect, test } from "bun:test"
 import type { UserMessage } from "@opencode-ai/sdk/v2"
 import { resetSessionModel, syncSessionModel } from "./session-model-helpers"
 
-const message = (input?: Partial<Pick<UserMessage, "agent" | "model" | "variant">>) =>
+const message = (input?: { agent?: string; model?: UserMessage["model"] }) =>
   ({
     id: "msg",
     sessionID: "session",
@@ -10,7 +10,6 @@ const message = (input?: Partial<Pick<UserMessage, "agent" | "model" | "variant"
     time: { created: 1 },
     agent: input?.agent ?? "build",
     model: input?.model ?? { providerID: "anthropic", modelID: "claude-sonnet-4" },
-    variant: input?.variant,
   }) as UserMessage
 
 describe("syncSessionModel", () => {
@@ -26,10 +25,12 @@ describe("syncSessionModel", () => {
           reset() {},
         },
       },
-      message({ variant: "high" }),
+      message({ model: { providerID: "anthropic", modelID: "claude-sonnet-4", variant: "high" } }),
     )
 
-    expect(calls).toEqual([message({ variant: "high" })])
+    expect(calls).toEqual([
+      message({ model: { providerID: "anthropic", modelID: "claude-sonnet-4", variant: "high" } }),
+    ])
   })
 })