Persist session model switches outside event flag (#26765)

packages/opencode/src/v2/event.ts

@@ -44,9 +44,10 @@ export function define<const Type extends string, Fields extends Schema.Struct.F
 export function run<Def extends SyncEvent.Definition>(
   def: Def,
   data: SyncEvent.Event<Def>["data"],
-  options?: { publish?: boolean },
+  // Temporary escape hatch while the full v2 event system remains experimental.
+  options?: { publish?: boolean; bypassExperimentalEventSystem?: boolean },
 ) {
-  if (!Flag.OPENCODE_EXPERIMENTAL_EVENT_SYSTEM) return
+  if (!options?.bypassExperimentalEventSystem && !Flag.OPENCODE_EXPERIMENTAL_EVENT_SYSTEM) return
   SyncEvent.run(def, data, options)
 }
 

packages/opencode/src/v2/session.ts

@@ -269,18 +269,26 @@ export const layer = Layer.effect(
       shell: Effect.fn("V2Session.shell")(function* (_input) {}),
       skill: Effect.fn("V2Session.skill")(function* (_input) {}),
       switchAgent: Effect.fn("V2Session.switchAgent")(function* (input) {
-        EventV2.run(SessionEvent.AgentSwitched.Sync, {
-          sessionID: input.sessionID,
-          timestamp: DateTime.makeUnsafe(Date.now()),
-          agent: input.agent,
-        })
+        EventV2.run(
+          SessionEvent.AgentSwitched.Sync,
+          {
+            sessionID: input.sessionID,
+            timestamp: DateTime.makeUnsafe(Date.now()),
+            agent: input.agent,
+          },
+          { bypassExperimentalEventSystem: true },
+        )
       }),
       switchModel: Effect.fn("V2Session.switchModel")(function* (input) {
-        EventV2.run(SessionEvent.ModelSwitched.Sync, {
-          sessionID: input.sessionID,
-          timestamp: DateTime.makeUnsafe(Date.now()),
-          model: input.model,
-        })
+        EventV2.run(
+          SessionEvent.ModelSwitched.Sync,
+          {
+            sessionID: input.sessionID,
+            timestamp: DateTime.makeUnsafe(Date.now()),
+            model: input.model,
+          },
+          { bypassExperimentalEventSystem: true },
+        )
       }),
       subagent: Effect.fn("V2Session.subagent")(function* (input) {
         const parent = yield* result.get(input.parentID)