diff --git a/src/config/index.ts b/src/config/index.ts
index 213c78d59..a561a2e66 100644
--- a/src/config/index.ts
+++ b/src/config/index.ts
@@ -32,4 +32,5 @@ export type {
   SisyphusConfig,
   SisyphusTasksConfig,
   RuntimeFallbackConfig,
+  FallbackModels,
 } from "./schema"
diff --git a/src/hooks/runtime-fallback/index.test.ts b/src/hooks/runtime-fallback/index.test.ts
index d73fa144d..bd4a0122e 100644
--- a/src/hooks/runtime-fallback/index.test.ts
+++ b/src/hooks/runtime-fallback/index.test.ts
@@ -522,9 +522,22 @@ describe("runtime-fallback", () => {
   })
 
   describe("fallback models configuration", () => {
+    function createMockPluginConfigWithAgentFallback(agentName: string, fallbackModels: string[]): OhMyOpenCodeConfig {
+      return {
+        agents: {
+          [agentName]: {
+            fallback_models: fallbackModels,
+          },
+        },
+      }
+    }
+
     test("should use agent-level fallback_models", async () => {
       const input = createMockPluginInput()
-      const hook = createRuntimeFallbackHook(input, { config: createMockConfig() })
+      const hook = createRuntimeFallbackHook(input, {
+        config: createMockConfig({ notify_on_fallback: false }),
+        pluginConfig: createMockPluginConfigWithAgentFallback("oracle", ["openai/gpt-5.2", "google/gemini-3-pro"]),
+      })
       const sessionID = "test-agent-fallback"
 
       //#given - agent with custom fallback models
@@ -543,13 +556,17 @@ describe("runtime-fallback", () => {
         },
       })
 
-      //#then - should use oracle's fallback models
-      const fallbackLog = logCalls.find((c) => c.msg.includes("No fallback models configured") || c.msg.includes("Fallback triggered"))
+      //#then - should prepare fallback to openai/gpt-5.2
+      const fallbackLog = logCalls.find((c) => c.msg.includes("Preparing fallback"))
       expect(fallbackLog).toBeDefined()
+      expect(fallbackLog?.data).toMatchObject({ from: "anthropic/claude-opus-4-5", to: "openai/gpt-5.2" })
     })
 
     test("should detect agent from sessionID pattern", async () => {
-      const hook = createRuntimeFallbackHook(createMockPluginInput(), { config: createMockConfig() })
+      const hook = createRuntimeFallbackHook(createMockPluginInput(), {
+        config: createMockConfig({ notify_on_fallback: false }),
+        pluginConfig: createMockPluginConfigWithAgentFallback("sisyphus", ["openai/gpt-5.2"]),
+      })
       const sessionID = "sisyphus-session-123"
 
       await hook.event({
@@ -566,8 +583,10 @@ describe("runtime-fallback", () => {
         },
       })
 
-      const errorLog = logCalls.find((c) => c.msg.includes("session.error received"))
-      expect(errorLog?.data).toMatchObject({ sessionID })
+      //#then - should detect sisyphus from sessionID and use its fallback
+      const fallbackLog = logCalls.find((c) => c.msg.includes("Preparing fallback"))
+      expect(fallbackLog).toBeDefined()
+      expect(fallbackLog?.data).toMatchObject({ to: "openai/gpt-5.2" })
     })
   })
 
diff --git a/src/hooks/runtime-fallback/index.ts b/src/hooks/runtime-fallback/index.ts
index 134aaeb13..8c07e67d1 100644
--- a/src/hooks/runtime-fallback/index.ts
+++ b/src/hooks/runtime-fallback/index.ts
@@ -115,7 +115,26 @@ function getFallbackModelsForSession(
     if (result) return result
   }
 
-  const sessionAgentMatch = sessionID.match(/\b(sisyphus|oracle|librarian|explore|prometheus|atlas|metis|momus|hephaestus|sisyphus-junior|build|plan|multimodal-looker)\b/i)
+  const AGENT_NAMES = [
+    "sisyphus",
+    "oracle",
+    "librarian",
+    "explore",
+    "prometheus",
+    "atlas",
+    "metis",
+    "momus",
+    "hephaestus",
+    "sisyphus-junior",
+    "build",
+    "plan",
+    "multimodal-looker",
+  ]
+  const agentPattern = new RegExp(
+    `(?:^|[^a-zA-Z0-9_-])(${AGENT_NAMES.map((a) => a.replace(/-/g, "\\-")).join("|")})(?:$|[^a-zA-Z0-9_-])`,
+    "i",
+  )
+  const sessionAgentMatch = sessionID.match(agentPattern)
   if (sessionAgentMatch) {
     const detectedAgent = sessionAgentMatch[1].toLowerCase()
     const result = tryGetFallbackFromAgent(detectedAgent)
diff --git a/src/shared/model-resolver.ts b/src/shared/model-resolver.ts
index a9e450fb2..9618b15ed 100644
--- a/src/shared/model-resolver.ts
+++ b/src/shared/model-resolver.ts
@@ -73,3 +73,13 @@ export function resolveModelWithFallback(
 		variant: resolved.variant,
 	}
 }
+
+/**
+ * Normalizes fallback_models config (which can be string or string[]) to string[]
+ * Centralized helper to avoid duplicated normalization logic
+ */
+export function normalizeFallbackModels(models: string | string[] | undefined): string[] | undefined {
+	if (!models) return undefined
+	if (typeof models === "string") return [models]
+	return models
+}
diff --git a/src/tools/delegate-task/sync-task.ts b/src/tools/delegate-task/sync-task.ts
index 13b701c24..75b3f9e40 100644
--- a/src/tools/delegate-task/sync-task.ts
+++ b/src/tools/delegate-task/sync-task.ts
@@ -150,6 +150,7 @@ session_id: ${sessionID}
   } finally {
     if (syncSessionID) {
       subagentSessions.delete(syncSessionID)
+      SessionCategoryRegistry.remove(syncSessionID)
     }
   }
 }