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

2 files changed, 86 insertions, 0 deletions

diff --git a/packages/app/src/testing/model-selection.ts b/packages/app/src/testing/model-selection.ts
new file mode 100644
index 000000000..a5ea199ac
--- /dev/null
+++ b/packages/app/src/testing/model-selection.ts
@@ -0,0 +1,80 @@
+type ModelKey = {
+  providerID: string
+  modelID: string
+}
+
+type State = {
+  agent?: string
+  model?: ModelKey | null
+  variant?: string | null
+}
+
+export type ModelProbeState = {
+  dir?: string
+  sessionID?: string
+  last?: {
+    type: "agent" | "model" | "variant"
+    agent?: string
+    model?: ModelKey | null
+    variant?: string | null
+  }
+  agent?: string
+  model?: (ModelKey & { name?: string }) | undefined
+  variant?: string | null
+  selected?: string | null
+  configured?: string
+  pick?: State
+  base?: State
+  current?: string
+}
+
+export type ModelWindow = Window & {
+  __opencode_e2e?: {
+    model?: {
+      enabled?: boolean
+      current?: ModelProbeState
+    }
+  }
+}
+
+const clone = (state?: State) => {
+  if (!state) return undefined
+  return {
+    ...state,
+    model: state.model ? { ...state.model } : state.model,
+  }
+}
+
+export const modelEnabled = () => {
+  if (typeof window === "undefined") return false
+  return (window as ModelWindow).__opencode_e2e?.model?.enabled === true
+}
+
+const root = () => {
+  if (!modelEnabled()) return
+  return (window as ModelWindow).__opencode_e2e?.model
+}
+
+export const modelProbe = {
+  set(input: ModelProbeState) {
+    const state = root()
+    if (!state) return
+    state.current = {
+      ...input,
+      model: input.model ? { ...input.model } : undefined,
+      last: input.last
+        ? {
+            ...input.last,
+            model: input.last.model ? { ...input.last.model } : input.last.model,
+          }
+        : undefined,
+      pick: clone(input.pick),
+      base: clone(input.base),
+    }
+  },
+  clear() {
+    const state = root()
+    if (!state) return
+    state.current = undefined
+  },
+}
diff --git a/packages/app/src/testing/terminal.ts b/packages/app/src/testing/terminal.ts
index 4c179dee3..af1c33309 100644
--- a/packages/app/src/testing/terminal.ts
+++ b/packages/app/src/testing/terminal.ts
@@ -1,3 +1,5 @@
+import type { ModelProbeState } from "./model-selection"
+
 export const terminalAttr = "data-pty-id"
 
 export type TerminalProbeState = {
@@ -13,6 +15,10 @@ type TerminalProbeControl = {
 
 export type E2EWindow = Window & {
   __opencode_e2e?: {
+    model?: {
+      enabled?: boolean
+      current?: ModelProbeState
+    }
     terminal?: {
       enabled?: boolean
       terminals?: Record<string, TerminalProbeState>