diff --git a/src/tools/delegate-task/executor-types.ts b/src/tools/delegate-task/executor-types.ts
index 8b430c9ce..7efc08370 100644
--- a/src/tools/delegate-task/executor-types.ts
+++ b/src/tools/delegate-task/executor-types.ts
@@ -31,6 +31,7 @@ export interface SessionMessage {
     role?: string
     time?: { created?: number }
     finish?: string
+    error?: unknown
     agent?: string
     model?: { providerID: string; modelID: string; variant?: string }
     modelID?: string
diff --git a/src/tools/delegate-task/sync-session-poller.test.ts b/src/tools/delegate-task/sync-session-poller.test.ts
index b8b2d85ff..494ce099c 100644
--- a/src/tools/delegate-task/sync-session-poller.test.ts
+++ b/src/tools/delegate-task/sync-session-poller.test.ts
@@ -28,6 +28,42 @@ describe("pollSyncSession", () => {
   })
 
   describe("native finish-based completion", () => {
+    test("returns terminal session error when assistant message contains info.error", async () => {
+      //#given
+      const { pollSyncSession } = require("./sync-session-poller")
+
+      const mockClient = {
+        session: {
+          messages: async () => ({
+            data: [
+              { info: { id: "msg_001", role: "user", time: { created: 1000 } } },
+              {
+                info: {
+                  id: "msg_002",
+                  role: "assistant",
+                  time: { created: 2000 },
+                  error: { data: { message: "Forbidden: Selected provider is forbidden" } },
+                },
+                parts: [],
+              },
+            ],
+          }),
+          status: async () => ({ data: { "ses_test": { type: "idle" } } }),
+        },
+      }
+
+      //#when
+      const result = await pollSyncSession(createMockCtx(), mockClient, {
+        sessionID: "ses_test",
+        agentToUse: "test-agent",
+        toastManager: null,
+        taskId: undefined,
+      })
+
+      //#then
+      expect(result).toBe("Forbidden: Selected provider is forbidden")
+    })
+
     test("detects completion when assistant message has terminal finish reason", async () => {
       //#given - session messages with a terminal assistant finish ("end_turn")
       //         and the assistant id > user id (native opencode condition)
diff --git a/src/tools/delegate-task/sync-session-poller.ts b/src/tools/delegate-task/sync-session-poller.ts
index d9bc40d01..810786223 100644
--- a/src/tools/delegate-task/sync-session-poller.ts
+++ b/src/tools/delegate-task/sync-session-poller.ts
@@ -3,6 +3,7 @@ import type { SessionMessage } from "./executor-types"
 import { getDefaultSyncPollTimeoutMs, getTimingConfig } from "./timing"
 import { log } from "../../shared/logger"
 import { normalizeSDKResponse } from "../../shared"
+import { extractErrorMessage } from "../../features/background-agent/error-classifier"
 
 const NON_TERMINAL_FINISH_REASONS = new Set(["tool-calls", "unknown"])
 const PENDING_TOOL_PART_TYPES = new Set(["tool", "tool_use", "tool-call"])
@@ -32,6 +33,16 @@ async function fetchSessionMessages(
   return Array.isArray(rawData) ? (rawData as SessionMessage[]) : []
 }
 
+function getTerminalSessionError(messages: SessionMessage[]): string | null {
+  const lastAssistant = [...messages].reverse().find((msg) => msg.info?.role === "assistant")
+  if (!lastAssistant?.info || !("error" in lastAssistant.info)) {
+    return null
+  }
+
+  const errorMessage = extractErrorMessage((lastAssistant.info as { error?: unknown }).error)
+  return errorMessage && errorMessage.length > 0 ? errorMessage : "Session error"
+}
+
 export function isSessionComplete(messages: SessionMessage[]): boolean {
   let lastUser: SessionMessage | undefined
   let lastAssistant: SessionMessage | undefined
@@ -137,6 +148,12 @@ export async function pollSyncSession(
       continue
     }
 
+    const sessionError = getTerminalSessionError(messages)
+    if (sessionError) {
+      log("[task] Poll detected terminal session error", { sessionID: input.sessionID, sessionError })
+      return sessionError
+    }
+
     if (isSessionComplete(messages)) {
       log("[task] Poll complete - terminal finish detected", { sessionID: input.sessionID, pollCount })
       break
diff --git a/src/tools/delegate-task/sync-task-fallback.ts b/src/tools/delegate-task/sync-task-fallback.ts
index 6ad64ef3d..fbbc24316 100644
--- a/src/tools/delegate-task/sync-task-fallback.ts
+++ b/src/tools/delegate-task/sync-task-fallback.ts
@@ -22,13 +22,14 @@ export async function retrySyncPromptWithFallbacks(input: {
   categoryModel: DelegatedModelConfig | undefined
   fallbackChain: FallbackEntry[] | undefined
   sendPrompt: (categoryModel: DelegatedModelConfig) => Promise<string | null>
-}): Promise<{ promptError: string | null; categoryModel: DelegatedModelConfig | undefined }> {
+}): Promise<{ promptError: string | null; categoryModel: DelegatedModelConfig | undefined; fallbackState?: ModelFallbackState }> {
   const { sessionID, initialError, categoryModel, fallbackChain, sendPrompt } = input
 
   if (!categoryModel || !fallbackChain || fallbackChain.length === 0) {
     return {
       promptError: initialError,
       categoryModel,
+      fallbackState: undefined,
     }
   }
 
@@ -48,6 +49,7 @@ export async function retrySyncPromptWithFallbacks(input: {
       return {
         promptError: finalError,
         categoryModel,
+        fallbackState,
       }
     }
 
@@ -57,6 +59,7 @@ export async function retrySyncPromptWithFallbacks(input: {
       return {
         promptError: null,
         categoryModel: fallbackModel,
+        fallbackState,
       }
     }
 
@@ -66,3 +69,12 @@ export async function retrySyncPromptWithFallbacks(input: {
     fallbackState.pending = true
   }
 }
+
+export function getNextSyncFallbackModel(
+  sessionID: string,
+  fallbackState: ModelFallbackState | undefined,
+): DelegatedModelConfig | null {
+  if (!fallbackState) return null
+  const nextFallback = getNextReachableFallback(sessionID, fallbackState)
+  return nextFallback ? toDelegatedModelConfig(nextFallback) : null
+}
diff --git a/src/tools/delegate-task/sync-task.test.ts b/src/tools/delegate-task/sync-task.test.ts
index a81fe4eb1..80c0572e3 100644
--- a/src/tools/delegate-task/sync-task.test.ts
+++ b/src/tools/delegate-task/sync-task.test.ts
@@ -426,6 +426,96 @@ describe("executeSyncTask - cleanup on error paths", () => {
     expect(deleteCalls[0]).toBe("ses_test_12345678")
   })
 
+  test("retries sync session on retryable runtime session error using next fallback model", async () => {
+    const mockClient = {
+      session: {
+        create: async () => ({ data: { id: "ignored" } }),
+      },
+    }
+
+    const { executeSyncTask } = require("./sync-task")
+    const createdSessions: string[] = []
+    const attemptedModels: Array<{ providerID: string; modelID: string; variant?: string } | undefined> = []
+    const polledSessions: string[] = []
+
+    const deps = {
+      createSyncSession: async () => {
+        const sessionID = createdSessions.length === 0 ? "ses_first" : "ses_second"
+        createdSessions.push(sessionID)
+        return { ok: true as const, sessionID }
+      },
+      sendSyncPrompt: async (_client: unknown, input: { categoryModel?: { providerID: string; modelID: string; variant?: string } }) => {
+        attemptedModels.push(input.categoryModel)
+        return null
+      },
+      pollSyncSession: async (_ctx: unknown, _client: unknown, input: { sessionID: string }) => {
+        polledSessions.push(input.sessionID)
+        return input.sessionID === "ses_first"
+          ? "Forbidden: Selected provider is forbidden"
+          : null
+      },
+      fetchSyncResult: async (_client: unknown, sessionID: string) => ({ ok: true as const, textContent: `Result from ${sessionID}` }),
+    }
+
+    const metadataCalls: any[] = []
+    const mockCtx = {
+      sessionID: "parent-session",
+      callID: "call-123",
+      metadata: (input: any) => { metadataCalls.push(input) },
+    }
+
+    const mockExecutorCtx = {
+      client: mockClient,
+      directory: "/tmp",
+      onSyncSessionCreated: null,
+      modelFallbackControllerAccessor: {
+        setSessionFallbackChain: () => {},
+        clearSessionFallbackChain: () => {},
+      },
+    }
+
+    const args = {
+      prompt: "test prompt",
+      description: "test task",
+      category: "quick",
+      load_skills: [],
+      run_in_background: false,
+      command: null,
+    }
+
+    const initialModel = {
+      providerID: "genai-proxy-openai",
+      modelID: "gpt-5.4-mini",
+      variant: undefined,
+    }
+    const fallbackChain = [
+      { providers: ["genai-proxy-openai"], model: "gpt-5.4-mini" },
+      { providers: ["genai-proxy-aws"], model: "us.anthropic.claude-haiku-4-5-20251001-v1:0" },
+    ]
+
+    const result = await executeSyncTask(args, mockCtx, mockExecutorCtx, {
+      sessionID: "parent-session",
+    }, "sisyphus-junior", initialModel, undefined, undefined, fallbackChain, deps)
+
+    expect(createdSessions).toEqual(["ses_first", "ses_second"])
+    expect(polledSessions).toEqual(["ses_first", "ses_second"])
+    expect(attemptedModels).toEqual([
+      { providerID: "genai-proxy-openai", modelID: "gpt-5.4-mini", variant: undefined },
+      { providerID: "genai-proxy-aws", modelID: "us.anthropic.claude-haiku-4-5-20251001-v1:0", variant: undefined },
+    ])
+    expect(result).toContain("Result from ses_second")
+    expect(deleteCalls).toContain("ses_first")
+
+    const finalMetadata = metadataCalls.at(-1)
+    expect(finalMetadata.metadata.sessionId).toBe("ses_second")
+    expect(finalMetadata.metadata.taskId).toBe("ses_second")
+    expect(finalMetadata.metadata.model).toEqual({
+      providerID: "genai-proxy-aws",
+      modelID: "us.anthropic.claude-haiku-4-5-20251001-v1:0",
+      variant: undefined,
+    })
+  })
+
   test("depth regression: blocks spawn when reserveSubagentSpawn throws depth limit error", async () => {
     // This is a smoke test guarding against regressions where the depth limit
     // would be silently bypassed (e.g. via a fallback path that hardcodes
diff --git a/src/tools/delegate-task/sync-task.ts b/src/tools/delegate-task/sync-task.ts
index b1a0d6f38..758d516f2 100644
--- a/src/tools/delegate-task/sync-task.ts
+++ b/src/tools/delegate-task/sync-task.ts
@@ -9,9 +9,11 @@ import { SessionCategoryRegistry } from "../../shared/session-category-registry"
 import { formatDuration } from "./time-formatter"
 import { formatDetailedError } from "./error-formatting"
 import { syncTaskDeps, type SyncTaskDeps } from "./sync-task-deps"
-import { retrySyncPromptWithFallbacks } from "./sync-task-fallback"
+import { getNextSyncFallbackModel, retrySyncPromptWithFallbacks } from "./sync-task-fallback"
 import { buildTaskMetadataBlock } from "../../features/tool-metadata-store/task-metadata-contract"
 import { resolveMetadataModel } from "./resolve-metadata-model"
+import { shouldRetryError } from "../../shared/model-error-classifier"
+import type { ModelFallbackState } from "../../hooks/model-fallback/hook"
 
 export async function executeSyncTask(
   args: DelegateTaskArgs,
@@ -147,44 +149,97 @@ export async function executeSyncTask(
     }
 
     let effectiveCategoryModel = categoryModel
-    let promptError = await deps.sendSyncPrompt(client, {
-      ...syncPromptInput,
-      categoryModel: effectiveCategoryModel,
-    })
-    if (promptError) {
-      const promptResult = await retrySyncPromptWithFallbacks({
-        sessionID,
-        initialError: promptError,
-        categoryModel: effectiveCategoryModel,
-        fallbackChain,
-        sendPrompt: async (fallbackModel) => {
-          return deps.sendSyncPrompt(client, {
-            ...syncPromptInput,
-            categoryModel: fallbackModel,
-          })
-        },
-      })
+    let fallbackState: ModelFallbackState | undefined = effectiveCategoryModel && fallbackChain?.length
+      ? {
+          providerID: effectiveCategoryModel.providerID,
+          modelID: effectiveCategoryModel.modelID,
+          fallbackChain,
+          attemptCount: 0,
+          pending: true,
+        }
+      : undefined
+    let activeSessionID = sessionID
 
-      promptError = promptResult.promptError
-      effectiveCategoryModel = promptResult.categoryModel
-
-      if (promptError) {
-        return promptError
-      }
+    const cleanupRetrySession = (currentSessionID: string): void => {
+      subagentSessions.delete(currentSessionID)
+      syncSubagentSessions.delete(currentSessionID)
+      executorCtx.modelFallbackControllerAccessor?.clearSessionFallbackChain(currentSessionID)
+      SessionCategoryRegistry.remove(currentSessionID)
     }
 
     try {
-      const pollError = await deps.pollSyncSession(ctx, client, {
-        sessionID,
-        agentToUse,
-        toastManager,
-        taskId,
-      }, syncPollTimeoutMs)
-      if (pollError) {
-        return pollError
-      }
+      while (true) {
+        let promptError = await deps.sendSyncPrompt(client, {
+          ...syncPromptInput,
+          sessionID: activeSessionID,
+          categoryModel: effectiveCategoryModel,
+        })
+        if (promptError) {
+          const promptResult = await retrySyncPromptWithFallbacks({
+            sessionID: activeSessionID,
+            initialError: promptError,
+            categoryModel: effectiveCategoryModel,
+            fallbackChain,
+            sendPrompt: async (fallbackModel) => {
+              return deps.sendSyncPrompt(client, {
+                ...syncPromptInput,
+                sessionID: activeSessionID,
+                categoryModel: fallbackModel,
+              })
+            },
+          })
 
-      const result = await deps.fetchSyncResult(client, sessionID)
+          promptError = promptResult.promptError
+          effectiveCategoryModel = promptResult.categoryModel
+          fallbackState = promptResult.fallbackState ?? fallbackState
+
+          if (promptError) {
+            return promptError
+          }
+        }
+
+        const pollError = await deps.pollSyncSession(ctx, client, {
+          sessionID: activeSessionID,
+          agentToUse,
+          toastManager,
+          taskId,
+        }, syncPollTimeoutMs)
+        if (pollError) {
+          const nextFallbackModel = shouldRetryError({ message: pollError })
+            ? getNextSyncFallbackModel(activeSessionID, fallbackState)
+            : null
+          if (!nextFallbackModel) {
+            return pollError
+          }
+
+          cleanupRetrySession(activeSessionID)
+
+          const retrySessionResult = await deps.createSyncSession(client, {
+            parentSessionID: parentContext.sessionID,
+            agentToUse,
+            description: args.description,
+            defaultDirectory: directory,
+          })
+          if (!retrySessionResult.ok) {
+            return retrySessionResult.error
+          }
+
+          activeSessionID = retrySessionResult.sessionID
+          syncSessionID = retrySessionResult.sessionID
+          subagentSessions.add(activeSessionID)
+          syncSubagentSessions.add(activeSessionID)
+          setSessionAgent(activeSessionID, agentToUse)
+          executorCtx.modelFallbackControllerAccessor?.setSessionFallbackChain(activeSessionID, fallbackChain)
+
+          if (args.category) {
+            SessionCategoryRegistry.register(activeSessionID, args.category)
+          }
+
+          effectiveCategoryModel = nextFallbackModel
+          continue
+        }
+
+        const result = await deps.fetchSyncResult(client, activeSessionID)
       if (!result.ok) {
         return result.error
       }
@@ -205,6 +260,25 @@ export async function executeSyncTask(
         modelRoutingNote = `\nModel: ${actualModelStr}${args.category ? ` (category: ${args.category})` : ""}`
       }
 
+      await publishToolMetadata(ctx, {
+        title: args.description,
+        metadata: {
+          prompt: args.prompt,
+          agent: agentToUse,
+          category: args.category,
+          ...(args.requested_subagent_type !== undefined ? { requested_subagent_type: args.requested_subagent_type } : {}),
+          load_skills: args.load_skills,
+          description: args.description,
+          run_in_background: args.run_in_background,
+          taskId: activeSessionID,
+          sessionId: activeSessionID,
+          sync: true,
+          spawnDepth: spawnContext.childDepth,
+          command: args.command,
+          model: resolveMetadataModel(effectiveCategoryModel, parentContext.model),
+        },
+      })
+
       return `Task completed in ${duration}.
 
 Agent: ${agentToUse}${args.category ? ` (category: ${args.category})` : ""}${modelRoutingNote}
@@ -214,11 +288,12 @@ Agent: ${agentToUse}${args.category ? ` (category: ${args.category})` : ""}${mod
 ${result.textContent || "(No text output)"}
 
 ${buildTaskMetadataBlock({
-        sessionId: sessionID,
-        taskId: sessionID,
+        sessionId: activeSessionID,
+        taskId: activeSessionID,
         agent: agentToUse,
         category: args.category,
       })}`
+      }
     } finally {
       if (toastManager && taskId !== undefined) {
         toastManager.removeTask(taskId)