Address review feedback for fallback fixes

assets/oh-my-opencode.schema.json

@@ -3011,6 +3011,9 @@
         },
         "disable_omo_env": {
           "type": "boolean"
+        },
+        "model_fallback_title": {
+          "type": "boolean"
         }
       },
       "additionalProperties": false

src/config/schema/experimental.ts

@@ -17,6 +17,10 @@ export const ExperimentalConfigSchema = z.object({
   safe_hook_creation: z.boolean().optional(),
   /** Disable auto-injected <omo-env> context in prompts (experimental) */
   disable_omo_env: z.boolean().optional(),
+  /** Enable hashline_edit tool for improved file editing with hash-based line anchors */
+  hashline_edit: z.boolean().optional(),
+  /** Append fallback model info to session title when a runtime fallback occurs (default: false) */
+  model_fallback_title: z.boolean().optional(),
 })
 
 export type ExperimentalConfig = z.infer<typeof ExperimentalConfigSchema>

src/features/background-agent/manager.test.ts

@@ -2920,6 +2920,39 @@ describe("BackgroundManager.handleEvent - session.deleted cascade", () => {
 })
 
 describe("BackgroundManager.handleEvent - session.error", () => {
+  const defaultRetryFallbackChain = [
+    { providers: ["quotio"], model: "claude-opus-4-6", variant: "max" },
+    { providers: ["quotio"], model: "gpt-5.3-codex", variant: "high" },
+  ]
+
+  const stubProcessKey = (manager: BackgroundManager) => {
+    ;(manager as unknown as { processKey: (key: string) => Promise<void> }).processKey = async () => {}
+  }
+
+  const createRetryTask = (manager: BackgroundManager, input: {
+    id: string
+    sessionID: string
+    description: string
+    concurrencyKey?: string
+    fallbackChain?: typeof defaultRetryFallbackChain
+  }) => {
+    const task = createMockTask({
+      id: input.id,
+      sessionID: input.sessionID,
+      parentSessionID: "parent-session",
+      parentMessageID: "msg-retry",
+      description: input.description,
+      agent: "sisyphus",
+      status: "running",
+      concurrencyKey: input.concurrencyKey,
+      model: { providerID: "quotio", modelID: "claude-opus-4-6-thinking" },
+      fallbackChain: input.fallbackChain ?? defaultRetryFallbackChain,
+      attemptCount: 0,
+    })
+    getTaskMap(manager).set(task.id, task)
+    return task
+  }
+
   test("sets task to error, releases concurrency, and cleans up", async () => {
     //#given
     const manager = createBackgroundManager()
@@ -3054,26 +3087,19 @@ describe("BackgroundManager.handleEvent - session.error", () => {
     const concurrencyKey = "quotio/claude-opus-4-6-thinking"
     await concurrencyManager.acquire(concurrencyKey)
 
-    ;(manager as unknown as { processKey: (key: string) => Promise<void> }).processKey = async () => {}
+    stubProcessKey(manager)
 
     const sessionID = "ses_error_retry"
-    const task = createMockTask({
+    const task = createRetryTask(manager, {
       id: "task-session-error-retry",
       sessionID,
-      parentSessionID: "parent-session",
-      parentMessageID: "msg-retry",
       description: "task that should retry",
-      agent: "sisyphus",
-      status: "running",
       concurrencyKey,
-      model: { providerID: "quotio", modelID: "claude-opus-4-6-thinking" },
       fallbackChain: [
         { providers: ["quotio"], model: "claude-opus-4-6", variant: "max" },
         { providers: ["quotio"], model: "claude-opus-4-5" },
       ],
-      attemptCount: 0,
     })
-    getTaskMap(manager).set(task.id, task)
 
     //#when
     manager.handleEvent({
@@ -3107,25 +3133,14 @@ describe("BackgroundManager.handleEvent - session.error", () => {
   test("retry path triggers on session.status retry events", async () => {
     //#given
     const manager = createBackgroundManager()
-    ;(manager as unknown as { processKey: (key: string) => Promise<void> }).processKey = async () => {}
+    stubProcessKey(manager)
 
     const sessionID = "ses_status_retry"
-    const task = createMockTask({
+    const task = createRetryTask(manager, {
       id: "task-status-retry",
       sessionID,
-      parentSessionID: "parent-session",
-      parentMessageID: "msg-status",
       description: "task that should retry on status",
-      agent: "sisyphus",
-      status: "running",
-      model: { providerID: "quotio", modelID: "claude-opus-4-6-thinking" },
-      fallbackChain: [
-        { providers: ["quotio"], model: "claude-opus-4-6", variant: "max" },
-        { providers: ["quotio"], model: "gpt-5.3-codex", variant: "high" },
-      ],
-      attemptCount: 0,
     })
-    getTaskMap(manager).set(task.id, task)
 
     //#when
     manager.handleEvent({
@@ -3154,25 +3169,14 @@ describe("BackgroundManager.handleEvent - session.error", () => {
   test("retry path triggers on message.updated assistant error events", async () => {
     //#given
     const manager = createBackgroundManager()
-    ;(manager as unknown as { processKey: (key: string) => Promise<void> }).processKey = async () => {}
+    stubProcessKey(manager)
 
     const sessionID = "ses_message_updated_retry"
-    const task = createMockTask({
+    const task = createRetryTask(manager, {
       id: "task-message-updated-retry",
       sessionID,
-      parentSessionID: "parent-session",
-      parentMessageID: "msg-message-updated",
       description: "task that should retry on message.updated",
-      agent: "sisyphus",
-      status: "running",
-      model: { providerID: "quotio", modelID: "claude-opus-4-6-thinking" },
-      fallbackChain: [
-        { providers: ["quotio"], model: "claude-opus-4-6", variant: "max" },
-        { providers: ["quotio"], model: "gpt-5.3-codex", variant: "high" },
-      ],
-      attemptCount: 0,
     })
-    getTaskMap(manager).set(task.id, task)
 
     //#when
     manager.handleEvent({

src/hooks/model-fallback/hook.ts

@@ -36,6 +36,20 @@ export type ModelFallbackState = {
  */
 const pendingModelFallbacks = new Map<string, ModelFallbackState>()
 const lastToastKey = new Map<string, string>()
+const sessionFallbackChains = new Map<string, FallbackEntry[]>()
+
+export function setSessionFallbackChain(sessionID: string, fallbackChain: FallbackEntry[] | undefined): void {
+  if (!sessionID) return
+  if (!fallbackChain || fallbackChain.length === 0) {
+    sessionFallbackChains.delete(sessionID)
+    return
+  }
+  sessionFallbackChains.set(sessionID, fallbackChain)
+}
+
+export function clearSessionFallbackChain(sessionID: string): void {
+  sessionFallbackChains.delete(sessionID)
+}
 
 /**
  * Sets a pending model fallback for a session.
@@ -49,12 +63,16 @@ export function setPendingModelFallback(
 ): boolean {
   const agentKey = getAgentConfigKey(agentName)
   const requirements = AGENT_MODEL_REQUIREMENTS[agentKey]
-  if (!requirements || !requirements.fallbackChain || requirements.fallbackChain.length === 0) {
+  const sessionFallback = sessionFallbackChains.get(sessionID)
+  const fallbackChain = sessionFallback && sessionFallback.length > 0
+    ? sessionFallback
+    : requirements?.fallbackChain
+
+  if (!fallbackChain || fallbackChain.length === 0) {
     log("[model-fallback] No fallback chain for agent: " + agentName + " (key: " + agentKey + ")")
     return false
   }
 
-  const fallbackChain = requirements.fallbackChain
   const existing = pendingModelFallbacks.get(sessionID)
 
   if (existing) {

src/plugin/event.model-fallback.test.ts

@@ -6,15 +6,9 @@ import { _resetForTesting, setMainSession } from "../features/claude-code-sessio
 import { createModelFallbackHook, clearPendingModelFallback } from "../hooks/model-fallback/hook"
 
 describe("createEventHandler - model fallback", () => {
-  afterEach(() => {
+  const createHandler = (args?: { hooks?: any }) => {
-    _resetForTesting()
-  })
-
-  test("triggers retry prompt for assistant message.updated APIError payloads (headless resume)", async () => {
-    //#given
     const abortCalls: string[] = []
     const promptCalls: string[] = []
-    const sessionID = "ses_message_updated_fallback"
 
     const handler = createEventHandler({
       ctx: {
@@ -46,9 +40,21 @@ describe("createEventHandler - model fallback", () => {
           disconnectSession: async () => {},
         },
       } as any,
-      hooks: {} as any,
+      hooks: args?.hooks ?? ({} as any),
     })
 
+    return { handler, abortCalls, promptCalls }
+  }
+
+  afterEach(() => {
+    _resetForTesting()
+  })
+
+  test("triggers retry prompt for assistant message.updated APIError payloads (headless resume)", async () => {
+    //#given
+    const sessionID = "ses_message_updated_fallback"
+    const { handler, abortCalls, promptCalls } = createHandler()
+
     //#when
     await handler({
       event: {
@@ -87,43 +93,9 @@ describe("createEventHandler - model fallback", () => {
 
   test("triggers retry prompt for nested model error payloads", async () => {
     //#given
-    const abortCalls: string[] = []
-    const promptCalls: string[] = []
     const sessionID = "ses_main_fallback_nested"
     setMainSession(sessionID)
-
+    const { handler, abortCalls, promptCalls } = createHandler()
-    const handler = createEventHandler({
-      ctx: {
-        directory: "/tmp",
-        client: {
-          session: {
-            abort: async ({ path }: { path: { id: string } }) => {
-              abortCalls.push(path.id)
-              return {}
-            },
-            prompt: async ({ path }: { path: { id: string } }) => {
-              promptCalls.push(path.id)
-              return {}
-            },
-          },
-        },
-      } as any,
-      pluginConfig: {} as any,
-      firstMessageVariantGate: {
-        markSessionCreated: () => {},
-        clear: () => {},
-      },
-      managers: {
-        tmuxSessionManager: {
-          onSessionCreated: async () => {},
-          onSessionDeleted: async () => {},
-        },
-        skillMcpManager: {
-          disconnectSession: async () => {},
-        },
-      } as any,
-      hooks: {} as any,
-    })
 
     //#when
     await handler({
@@ -151,48 +123,13 @@ describe("createEventHandler - model fallback", () => {
 
   test("triggers retry prompt on session.status retry events and applies fallback", async () => {
     //#given
-    const abortCalls: string[] = []
-    const promptCalls: string[] = []
     const sessionID = "ses_status_retry_fallback"
     setMainSession(sessionID)
     clearPendingModelFallback(sessionID)
 
     const modelFallback = createModelFallbackHook()
 
-    const handler = createEventHandler({
+    const { handler, abortCalls, promptCalls } = createHandler({ hooks: { modelFallback } })
-      ctx: {
-        directory: "/tmp",
-        client: {
-          session: {
-            abort: async ({ path }: { path: { id: string } }) => {
-              abortCalls.push(path.id)
-              return {}
-            },
-            prompt: async ({ path }: { path: { id: string } }) => {
-              promptCalls.push(path.id)
-              return {}
-            },
-          },
-        },
-      } as any,
-      pluginConfig: {} as any,
-      firstMessageVariantGate: {
-        markSessionCreated: () => {},
-        clear: () => {},
-      },
-      managers: {
-        tmuxSessionManager: {
-          onSessionCreated: async () => {},
-          onSessionDeleted: async () => {},
-        },
-        skillMcpManager: {
-          disconnectSession: async () => {},
-        },
-      } as any,
-      hooks: {
-        modelFallback,
-      } as any,
-    })
 
     const chatMessageHandler = createChatMessageHandler({
       ctx: {

src/plugin/event.ts

@@ -13,7 +13,7 @@ import {
 import { resetMessageCursor } from "../shared"
 import { lspManager } from "../tools"
 import { shouldRetryError } from "../shared/model-error-classifier"
-import { clearPendingModelFallback, setPendingModelFallback } from "../hooks/model-fallback/hook"
+import { clearPendingModelFallback, clearSessionFallbackChain, setPendingModelFallback } from "../hooks/model-fallback/hook"
 import { clearSessionModel, setSessionModel } from "../shared/session-model-state"
 
 import type { CreatedHooks } from "../create-hooks"
@@ -135,11 +135,11 @@ export function createEventHandler(args: {
   const DEDUP_WINDOW_MS = 500
 
   const shouldAutoRetrySession = (sessionID: string): boolean => {
+    if (syncSubagentSessions.has(sessionID)) return true
     const mainSessionID = getMainSessionID()
     if (mainSessionID) return sessionID === mainSessionID
     // Headless runs (or resumed sessions) may not emit session.created, so mainSessionID can be unset.
     // In that case, treat any non-subagent session as the "main" interactive session.
-    if (syncSubagentSessions.has(sessionID)) return true
     return !subagentSessions.has(sessionID)
   }
 
@@ -213,6 +213,7 @@ export function createEventHandler(args: {
         lastHandledRetryStatusKey.delete(sessionInfo.id)
         lastKnownModelBySession.delete(sessionInfo.id)
         clearPendingModelFallback(sessionInfo.id)
+        clearSessionFallbackChain(sessionInfo.id)
         resetMessageCursor(sessionInfo.id)
         firstMessageVariantGate.clear(sessionInfo.id)
         clearSessionModel(sessionInfo.id)

src/plugin/hooks/create-session-hooks.ts

@@ -105,6 +105,8 @@ export function createSessionHooks(args: {
     ? safeHook("think-mode", () => createThinkModeHook())
     : null
 
+  const enableFallbackTitle = pluginConfig.experimental?.model_fallback_title ?? false
+  const fallbackTitleMaxEntries = 200
   const fallbackTitleState = new Map<string, { baseTitle?: string; lastKey?: string }>()
   const updateFallbackTitle = async (input: {
     sessionID: string
@@ -112,6 +114,7 @@ export function createSessionHooks(args: {
     modelID: string
     variant?: string
   }) => {
+    if (!enableFallbackTitle) return
     const key = `${input.providerID}/${input.modelID}${input.variant ? `:${input.variant}` : ""}`
     const existing = fallbackTitleState.get(input.sessionID) ?? {}
     if (existing.lastKey === key) return
@@ -142,26 +145,32 @@ export function createSessionHooks(args: {
 
     existing.lastKey = key
     fallbackTitleState.set(input.sessionID, existing)
+    if (fallbackTitleState.size > fallbackTitleMaxEntries) {
+      const oldestKey = fallbackTitleState.keys().next().value
+      if (oldestKey) fallbackTitleState.delete(oldestKey)
+    }
   }
 
-  // Model fallback hook - always enabled (no feature flag)
+  // Model fallback hook (configurable via disabled_hooks)
   // This handles automatic model switching when model errors occur
-  const modelFallback = safeHook("model-fallback", () =>
+  const modelFallback = isHookEnabled("model-fallback")
-    createModelFallbackHook({
+    ? safeHook("model-fallback", () =>
-      toast: async ({ title, message, variant, duration }) => {
+      createModelFallbackHook({
-        await ctx.client.tui
+        toast: async ({ title, message, variant, duration }) => {
-          .showToast({
+          await ctx.client.tui
-            body: {
+            .showToast({
-              title,
+              body: {
-              message,
+                title,
-              variant: variant ?? "warning",
+                message,
-              duration: duration ?? 5000,
+                variant: variant ?? "warning",
-            },
+                duration: duration ?? 5000,
-          })
+              },
-          .catch(() => {})
+            })
-      },
+            .catch(() => {})
-      onApplied: updateFallbackTitle,
+        },
-    }))
+        onApplied: enableFallbackTitle ? updateFallbackTitle : undefined,
+      }))
+    : null
 
   const anthropicContextWindowLimitRecovery = isHookEnabled("anthropic-context-window-limit-recovery")
     ? safeHook("anthropic-context-window-limit-recovery", () =>

src/shared/model-requirements.ts

@@ -20,6 +20,18 @@ function fb(providers: string[] | string, model: string, variant?: string): Fall
   }
 }
 
+function dedupeChain(chain: FallbackEntry[]): FallbackEntry[] {
+  const seen = new Set<string>()
+  const result: FallbackEntry[] = []
+  for (const entry of chain) {
+    const key = `${entry.model}:${entry.variant ?? ""}`
+    if (seen.has(key)) continue
+    seen.add(key)
+    result.push(entry)
+  }
+  return result
+}
+
 // Provider preference rules:
 // - Never use the paid `opencode` provider as an automatic fallback.
 // - Prefer `quotio` when the same model exists across multiple providers.
@@ -82,12 +94,12 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
     requiresAnyModel: true,
   },
   oracle: {
-    fallbackChain: [
+    fallbackChain: dedupeChain([
       fb("quotio", "gpt-5.3-codex", "high"),
       fb("quotio", "claude-opus-4-6-thinking"),
       fb("quotio", "claude-sonnet-4-5-thinking"),
       ...QUALITY_CODING_CHAIN,
-    ],
+    ]),
   },
   librarian: {
     fallbackChain: [
@@ -111,35 +123,35 @@ export const AGENT_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
     ],
   },
   prometheus: {
-    fallbackChain: [
+    fallbackChain: dedupeChain([
       fb("quotio", "claude-opus-4-6-thinking"),
       fb("quotio", "gpt-5.3-codex", "high"),
       fb("quotio", "claude-sonnet-4-5-thinking"),
       ...QUALITY_CODING_CHAIN,
-    ],
+    ]),
   },
   metis: {
-    fallbackChain: [
+    fallbackChain: dedupeChain([
       fb("quotio", "claude-opus-4-6-thinking"),
       fb("quotio", "gpt-5.3-codex", "high"),
       fb("quotio", "claude-sonnet-4-5-thinking"),
       ...QUALITY_CODING_CHAIN,
-    ],
+    ]),
   },
   momus: {
-    fallbackChain: [
+    fallbackChain: dedupeChain([
       fb("quotio", "gpt-5.3-codex", "high"),
       fb("quotio", "claude-opus-4-6-thinking"),
       ...QUALITY_CODING_CHAIN,
-    ],
+    ]),
   },
   atlas: {
-    fallbackChain: [
+    fallbackChain: dedupeChain([
       fb("quotio", "claude-sonnet-4-5-thinking"),
       fb("quotio", "claude-opus-4-6-thinking"),
       fb("quotio", "gpt-5.3-codex", "medium"),
       ...QUALITY_CODING_CHAIN,
-    ],
+    ]),
   },
 }
 
@@ -155,13 +167,10 @@ export const CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
     ],
   },
   ultrabrain: {
-    fallbackChain: [
+    fallbackChain: dedupeChain([
       fb("quotio", "gpt-5.3-codex", "high"),
-      fb("quotio", "claude-opus-4-6-thinking"),
-      fb("nvidia", "stepfun-ai/step-3.5-flash"),
-      fb("nvidia", "qwen/qwen3.5-397b-a17b"),
       ...QUALITY_CODING_CHAIN,
-    ],
+    ]),
   },
   deep: {
     fallbackChain: [
@@ -187,11 +196,11 @@ export const CATEGORY_MODEL_REQUIREMENTS: Record<string, ModelRequirement> = {
     fallbackChain: SPEED_CHAIN,
   },
   "unspecified-high": {
-    fallbackChain: [
+    fallbackChain: dedupeChain([
       fb("quotio", "claude-opus-4-6-thinking"),
       fb("quotio", "gpt-5.3-codex", "high"),
       ...QUALITY_CODING_CHAIN,
-    ],
+    ]),
   },
   writing: {
     fallbackChain: [

src/tools/delegate-task/sync-task.test.ts

@@ -100,7 +100,7 @@ describe("executeSyncTask - cleanup on error paths", () => {
     //#when - executeSyncTask with fetchSyncResult failing
     const result = await executeSyncTask(args, mockCtx, mockExecutorCtx, {
       sessionID: "parent-session",
-    }, "test-agent", undefined, undefined, undefined, deps)
+    }, "test-agent", undefined, undefined, undefined, undefined, deps)
 
     //#then - should return error and cleanup resources
     expect(result).toBe("Fetch failed")
@@ -150,7 +150,7 @@ describe("executeSyncTask - cleanup on error paths", () => {
     //#when - executeSyncTask with pollSyncSession failing
     const result = await executeSyncTask(args, mockCtx, mockExecutorCtx, {
       sessionID: "parent-session",
-    }, "test-agent", undefined, undefined, undefined, deps)
+    }, "test-agent", undefined, undefined, undefined, undefined, deps)
 
     //#then - should return error and cleanup resources
     expect(result).toBe("Poll error")
@@ -200,7 +200,7 @@ describe("executeSyncTask - cleanup on error paths", () => {
     //#when - executeSyncTask completes successfully
     const result = await executeSyncTask(args, mockCtx, mockExecutorCtx, {
       sessionID: "parent-session",
-    }, "test-agent", undefined, undefined, undefined, deps)
+    }, "test-agent", undefined, undefined, undefined, undefined, deps)
 
     //#then - should complete and cleanup resources
     expect(result).toContain("Task completed")

src/tools/delegate-task/sync-task.ts

@@ -8,6 +8,7 @@ import { log } from "../../shared/logger"
 import { formatDuration } from "./time-formatter"
 import { formatDetailedError } from "./error-formatting"
 import { syncTaskDeps, type SyncTaskDeps } from "./sync-task-deps"
+import { setSessionFallbackChain, clearSessionFallbackChain } from "../../hooks/model-fallback/hook"
 
 export async function executeSyncTask(
   args: DelegateTaskArgs,
@@ -18,6 +19,7 @@ export async function executeSyncTask(
   categoryModel: { providerID: string; modelID: string; variant?: string } | undefined,
   systemContent: string | undefined,
   modelInfo?: ModelFallbackInfo,
+  fallbackChain?: import("../../shared/model-requirements").FallbackEntry[],
   deps: SyncTaskDeps = syncTaskDeps
 ): Promise<string> {
   const { client, directory, onSyncSessionCreated } = executorCtx
@@ -42,6 +44,7 @@ export async function executeSyncTask(
     subagentSessions.add(sessionID)
     syncSubagentSessions.add(sessionID)
     setSessionAgent(sessionID, agentToUse)
+    setSessionFallbackChain(sessionID, fallbackChain)
 
     if (onSyncSessionCreated) {
       log("[task] Invoking onSyncSessionCreated callback", { sessionID, parentID: parentContext.sessionID })
@@ -149,6 +152,7 @@ session_id: ${sessionID}
     if (syncSessionID) {
       subagentSessions.delete(syncSessionID)
       syncSubagentSessions.delete(syncSessionID)
+      clearSessionFallbackChain(syncSessionID)
     }
   }
 }

src/tools/delegate-task/tools.ts

@@ -223,7 +223,7 @@ Prompts MUST be in English.`
         return executeBackgroundTask(args, ctx, options, parentContext, agentToUse, categoryModel, systemContent, fallbackChain)
       }
 
-      return executeSyncTask(args, ctx, options, parentContext, agentToUse, categoryModel, systemContent, modelInfo)
+      return executeSyncTask(args, ctx, options, parentContext, agentToUse, categoryModel, systemContent, modelInfo, fallbackChain)
     },
   })
 }