refactor(model-fallback): fully encapsulate session state in factory closure

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/create-hooks.ts

@@ -2,6 +2,7 @@ import type { AvailableSkill } from "./agents/dynamic-agent-prompt-builder"
 import type { HookName, OhMyOpenCodeConfig } from "./config"
 import type { LoadedSkill } from "./features/opencode-skill-loader/types"
 import type { BackgroundManager } from "./features/background-agent"
+import type { ModelFallbackControllerAccessor } from "./hooks/model-fallback"
 import type { PluginContext } from "./plugin/types"
 import type { ModelCacheState } from "./plugin-state"
 
@@ -36,6 +37,7 @@ export function createHooks(args: {
   pluginConfig: OhMyOpenCodeConfig
   modelCacheState: ModelCacheState
   backgroundManager: BackgroundManager
+  modelFallbackControllerAccessor?: ModelFallbackControllerAccessor
   isHookEnabled: (hookName: HookName) => boolean
   safeHookEnabled: boolean
   mergedSkills: LoadedSkill[]
@@ -46,6 +48,7 @@ export function createHooks(args: {
     pluginConfig,
     modelCacheState,
     backgroundManager,
+    modelFallbackControllerAccessor,
     isHookEnabled,
     safeHookEnabled,
     mergedSkills,
@@ -56,6 +59,7 @@ export function createHooks(args: {
     ctx,
     pluginConfig,
     modelCacheState,
+    modelFallbackControllerAccessor,
     isHookEnabled,
     safeHookEnabled,
   })