From 38c925697bbbfcb17efa365273b8413bf324a654 Mon Sep 17 00:00:00 2001
From: Ravi Tharuma <RaviTharuma@users.noreply.github.com>
Date: Wed, 4 Mar 2026 20:25:25 +0100
Subject: [PATCH] Respect per-agent fallback chains in runtime fallback

---
 .../runtime-fallback/fallback-models.test.ts  | 66 +++++++++++++++++++
 src/hooks/runtime-fallback/fallback-models.ts | 16 +----
 2 files changed, 68 insertions(+), 14 deletions(-)
 create mode 100644 src/hooks/runtime-fallback/fallback-models.test.ts

diff --git a/src/hooks/runtime-fallback/fallback-models.test.ts b/src/hooks/runtime-fallback/fallback-models.test.ts
new file mode 100644
index 000000000..7cf3f8e32
--- /dev/null
+++ b/src/hooks/runtime-fallback/fallback-models.test.ts
@@ -0,0 +1,66 @@
+import { afterEach, describe, expect, test } from "bun:test"
+
+import { getFallbackModelsForSession } from "./fallback-models"
+import { SessionCategoryRegistry } from "../../shared/session-category-registry"
+
+describe("runtime-fallback fallback-models", () => {
+  afterEach(() => {
+    SessionCategoryRegistry.clear()
+  })
+
+  test("uses category fallback_models when session category is registered", () => {
+    //#given
+    const sessionID = "ses_runtime_fallback_category"
+    SessionCategoryRegistry.register(sessionID, "quick")
+    const pluginConfig = {
+      categories: {
+        quick: {
+          fallback_models: ["openai/gpt-5.2", "anthropic/claude-opus-4-6"],
+        },
+      },
+    } as any
+
+    //#when
+    const result = getFallbackModelsForSession(sessionID, undefined, pluginConfig)
+
+    //#then
+    expect(result).toEqual(["openai/gpt-5.2", "anthropic/claude-opus-4-6"])
+  })
+
+  test("uses agent-specific fallback_models when agent is resolved", () => {
+    //#given
+    const pluginConfig = {
+      agents: {
+        oracle: {
+          fallback_models: ["openai/gpt-5.2", "anthropic/claude-opus-4-6"],
+        },
+      },
+    } as any
+
+    //#when
+    const result = getFallbackModelsForSession("ses_runtime_fallback_agent", "oracle", pluginConfig)
+
+    //#then
+    expect(result).toEqual(["openai/gpt-5.2", "anthropic/claude-opus-4-6"])
+  })
+
+  test("does not fall back to another agent chain when agent cannot be resolved", () => {
+    //#given
+    const pluginConfig = {
+      agents: {
+        sisyphus: {
+          fallback_models: ["quotio/gpt-5.2", "quotio/glm-5", "quotio/kimi-k2.5"],
+        },
+        oracle: {
+          fallback_models: ["openai/gpt-5.2", "anthropic/claude-opus-4-6"],
+        },
+      },
+    } as any
+
+    //#when
+    const result = getFallbackModelsForSession("ses_runtime_fallback_unknown", undefined, pluginConfig)
+
+    //#then
+    expect(result).toEqual([])
+  })
+})
diff --git a/src/hooks/runtime-fallback/fallback-models.ts b/src/hooks/runtime-fallback/fallback-models.ts
index e7af3b40e..fb984bbec 100644
--- a/src/hooks/runtime-fallback/fallback-models.ts
+++ b/src/hooks/runtime-fallback/fallback-models.ts
@@ -1,5 +1,5 @@
 import type { OhMyOpenCodeConfig } from "../../config"
-import { AGENT_NAMES, agentPattern } from "./agent-resolver"
+import { agentPattern } from "./agent-resolver"
 import { HOOK_NAME } from "./constants"
 import { log } from "../../shared/logger"
 import { SessionCategoryRegistry } from "../../shared/session-category-registry"
@@ -51,19 +51,7 @@ export function getFallbackModelsForSession(
     if (result) return result
   }
 
-  const sisyphusFallback = tryGetFallbackFromAgent("sisyphus")
-  if (sisyphusFallback) {
-    log(`[${HOOK_NAME}] Using sisyphus fallback models (no agent detected)`, { sessionID })
-    return sisyphusFallback
-  }
-
-  for (const agentName of AGENT_NAMES) {
-    const result = tryGetFallbackFromAgent(agentName)
-    if (result) {
-      log(`[${HOOK_NAME}] Using ${agentName} fallback models (no agent detected)`, { sessionID })
-      return result
-    }
-  }
+  log(`[${HOOK_NAME}] No category/agent fallback models resolved for session`, { sessionID, agent })
 
   return []
 }