fix(app): model selection persist by session (#17348)

packages/app/src/pages/session/session-model-helpers.test.ts

@@ -14,145 +14,38 @@ const message = (input?: Partial<Pick<UserMessage, "agent" | "model" | "variant"
   }) as UserMessage
 
 describe("syncSessionModel", () => {
-  test("restores the last message model and variant", () => {
+  test("restores the last message through session state", () => {
     const calls: unknown[] = []
 
     syncSessionModel(
       {
-        agent: {
-          current() {
-            return undefined
-          },
-          set(value) {
-            calls.push(["agent", value])
-          },
-        },
-        model: {
-          set(value) {
-            calls.push(["model", value])
-          },
-          current() {
-            return { id: "claude-sonnet-4", provider: { id: "anthropic" } }
-          },
-          variant: {
-            set(value) {
-              calls.push(["variant", value])
-            },
+        session: {
+          restore(value) {
+            calls.push(value)
           },
+          reset() {},
         },
       },
       message({ variant: "high" }),
     )
 
-    expect(calls).toEqual([
-      ["agent", "build"],
-      ["model", { providerID: "anthropic", modelID: "claude-sonnet-4" }],
-      ["variant", "high"],
-    ])
-  })
-
-  test("skips variant when the model falls back", () => {
-    const calls: unknown[] = []
-
-    syncSessionModel(
-      {
-        agent: {
-          current() {
-            return undefined
-          },
-          set(value) {
-            calls.push(["agent", value])
-          },
-        },
-        model: {
-          set(value) {
-            calls.push(["model", value])
-          },
-          current() {
-            return { id: "gpt-5", provider: { id: "openai" } }
-          },
-          variant: {
-            set(value) {
-              calls.push(["variant", value])
-            },
-          },
-        },
-      },
-      message({ variant: "high" }),
-    )
-
-    expect(calls).toEqual([
-      ["agent", "build"],
-      ["model", { providerID: "anthropic", modelID: "claude-sonnet-4" }],
-    ])
+    expect(calls).toEqual([message({ variant: "high" })])
   })
 })
 
 describe("resetSessionModel", () => {
-  test("restores the current agent defaults", () => {
-    const calls: unknown[] = []
+  test("clears draft session state", () => {
+    const calls: string[] = []
 
     resetSessionModel({
-      agent: {
-        current() {
-          return {
-            model: { providerID: "anthropic", modelID: "claude-sonnet-4" },
-            variant: "high",
-          }
-        },
-        set() {},
-      },
-      model: {
-        set(value) {
-          calls.push(["model", value])
-        },
-        current() {
-          return undefined
-        },
-        variant: {
-          set(value) {
-            calls.push(["variant", value])
-          },
+      session: {
+        reset() {
+          calls.push("reset")
         },
+        restore() {},
       },
     })
 
-    expect(calls).toEqual([
-      ["model", { providerID: "anthropic", modelID: "claude-sonnet-4" }],
-      ["variant", "high"],
-    ])
-  })
-
-  test("clears the variant when the agent has none", () => {
-    const calls: unknown[] = []
-
-    resetSessionModel({
-      agent: {
-        current() {
-          return {
-            model: { providerID: "anthropic", modelID: "claude-sonnet-4" },
-          }
-        },
-        set() {},
-      },
-      model: {
-        set(value) {
-          calls.push(["model", value])
-        },
-        current() {
-          return undefined
-        },
-        variant: {
-          set(value) {
-            calls.push(["variant", value])
-          },
-        },
-      },
-    })
-
-    expect(calls).toEqual([
-      ["model", { providerID: "anthropic", modelID: "claude-sonnet-4" }],
-      ["variant", undefined],
-    ])
+    expect(calls).toEqual(["reset"])
   })
 })

packages/app/src/pages/session/session-model-helpers.ts

@@ -1,48 +1,16 @@
 import type { UserMessage } from "@opencode-ai/sdk/v2"
-import { batch } from "solid-js"
 
 type Local = {
-  agent: {
-    current():
-      | {
-          model?: UserMessage["model"]
-          variant?: string
-        }
-      | undefined
-    set(name: string | undefined): void
-  }
-  model: {
-    set(model: UserMessage["model"] | undefined): void
-    current():
-      | {
-          id: string
-          provider: { id: string }
-        }
-      | undefined
-    variant: {
-      set(value: string | undefined): void
-    }
+  session: {
+    reset(): void
+    restore(msg: UserMessage): void
   }
 }
 
 export const resetSessionModel = (local: Local) => {
-  const agent = local.agent.current()
-  if (!agent) return
-  batch(() => {
-    local.model.set(agent.model)
-    local.model.variant.set(agent.variant)
-  })
+  local.session.reset()
 }
 
 export const syncSessionModel = (local: Local, msg: UserMessage) => {
-  batch(() => {
-    local.agent.set(msg.agent)
-    local.model.set(msg.model)
-  })
-
-  const model = local.model.current()
-  if (!model) return
-  if (model.provider.id !== msg.model.providerID) return
-  if (model.id !== msg.model.modelID) return
-  local.model.variant.set(msg.variant)
+  local.session.restore(msg)
 }

packages/app/src/pages/session/use-session-commands.tsx

@@ -351,7 +351,7 @@ export const useSessionCommands = (actions: SessionCommandContext) => {
         description: language.t("command.model.choose.description"),
         keybind: "mod+'",
         slash: "model",
-        onSelect: () => dialog.show(() => <DialogSelectModel />),
+        onSelect: () => dialog.show(() => <DialogSelectModel model={local.model} />),
       }),
       mcpCommand({
         id: "mcp.toggle",