diff --git a/src/config/schema/agent-overrides.ts b/src/config/schema/agent-overrides.ts
index 7b3aa8d7a..623b35efd 100644
--- a/src/config/schema/agent-overrides.ts
+++ b/src/config/schema/agent-overrides.ts
@@ -59,7 +59,9 @@ export const AgentOverridesSchema = z.object({
   build: AgentOverrideConfigSchema.optional(),
   plan: AgentOverrideConfigSchema.optional(),
   sisyphus: AgentOverrideConfigSchema.optional(),
-  hephaestus: AgentOverrideConfigSchema.optional(),
+  hephaestus: AgentOverrideConfigSchema.extend({
+    allow_non_gpt_model: z.boolean().optional(),
+  }).optional(),
   "sisyphus-junior": AgentOverrideConfigSchema.optional(),
   "OpenCode-Builder": AgentOverrideConfigSchema.optional(),
   prometheus: AgentOverrideConfigSchema.optional(),
diff --git a/src/hooks/no-hephaestus-non-gpt/hook.ts b/src/hooks/no-hephaestus-non-gpt/hook.ts
index a1d08a2a1..e621c6d01 100644
--- a/src/hooks/no-hephaestus-non-gpt/hook.ts
+++ b/src/hooks/no-hephaestus-non-gpt/hook.ts
@@ -12,12 +12,16 @@ const TOAST_MESSAGE = [
 ].join("\n")
 const SISYPHUS_DISPLAY = getAgentDisplayName("sisyphus")
 
-function showToast(ctx: PluginInput, sessionID: string): void {
+type NoHephaestusNonGptHookOptions = {
+  allowNonGptModel?: boolean
+}
+
+function showToast(ctx: PluginInput, sessionID: string, variant: "error" | "warning"): void {
   ctx.client.tui.showToast({
     body: {
       title: TOAST_TITLE,
       message: TOAST_MESSAGE,
-      variant: "error",
+      variant,
       duration: 10000,
     },
   }).catch((error) => {
@@ -28,7 +32,10 @@ function showToast(ctx: PluginInput, sessionID: string): void {
   })
 }
 
-export function createNoHephaestusNonGptHook(ctx: PluginInput) {
+export function createNoHephaestusNonGptHook(
+  ctx: PluginInput,
+  options?: NoHephaestusNonGptHookOptions,
+) {
   return {
     "chat.message": async (input: {
       sessionID: string
@@ -40,9 +47,13 @@ export function createNoHephaestusNonGptHook(ctx: PluginInput) {
       const rawAgent = input.agent ?? getSessionAgent(input.sessionID) ?? ""
       const agentKey = getAgentConfigKey(rawAgent)
       const modelID = input.model?.modelID
+      const allowNonGptModel = options?.allowNonGptModel === true
 
       if (agentKey === "hephaestus" && modelID && !isGptModel(modelID)) {
-        showToast(ctx, input.sessionID)
+        showToast(ctx, input.sessionID, allowNonGptModel ? "warning" : "error")
+        if (allowNonGptModel) {
+          return
+        }
         input.agent = SISYPHUS_DISPLAY
         if (output?.message) {
           output.message.agent = SISYPHUS_DISPLAY
diff --git a/src/hooks/no-hephaestus-non-gpt/index.test.ts b/src/hooks/no-hephaestus-non-gpt/index.test.ts
index 51e1f3a0a..3440cccc8 100644
--- a/src/hooks/no-hephaestus-non-gpt/index.test.ts
+++ b/src/hooks/no-hephaestus-non-gpt/index.test.ts
@@ -1,3 +1,5 @@
+/// <reference types="bun-types" />
+
 import { describe, expect, spyOn, test } from "bun:test"
 import { _resetForTesting, updateSessionAgent } from "../../features/claude-code-session-state"
 import { getAgentDisplayName } from "../../shared/agent-display-names"
@@ -8,7 +10,7 @@ const SISYPHUS_DISPLAY = getAgentDisplayName("sisyphus")
 
 function createOutput() {
   return {
-    message: {},
+    message: {} as { agent?: string; [key: string]: unknown },
     parts: [],
   }
 }
@@ -16,7 +18,7 @@ function createOutput() {
 describe("no-hephaestus-non-gpt hook", () => {
   test("shows toast on every chat.message when hephaestus uses non-gpt model", async () => {
     // given - hephaestus with claude model
-    const showToast = spyOn({ fn: async () => ({}) }, "fn")
+    const showToast = spyOn({ fn: async (_input: unknown) => ({}) }, "fn")
     const hook = createNoHephaestusNonGptHook({
       client: { tui: { showToast } },
     } as any)
@@ -49,9 +51,38 @@ describe("no-hephaestus-non-gpt hook", () => {
     })
   })
 
+  test("shows warning and does not switch agent when allow_non_gpt_model is enabled", async () => {
+    // given - hephaestus with claude model and opt-out enabled
+    const showToast = spyOn({ fn: async (_input: unknown) => ({}) }, "fn")
+    const hook = createNoHephaestusNonGptHook({
+      client: { tui: { showToast } },
+    } as any, {
+      allowNonGptModel: true,
+    })
+
+    const output = createOutput()
+
+    // when - chat.message runs
+    await hook["chat.message"]?.({
+      sessionID: "ses_opt_out",
+      agent: HEPHAESTUS_DISPLAY,
+      model: { providerID: "anthropic", modelID: "claude-opus-4-6" },
+    }, output)
+
+    // then - warning toast is shown but agent is not switched
+    expect(showToast).toHaveBeenCalledTimes(1)
+    expect(output.message.agent).toBeUndefined()
+    expect(showToast.mock.calls[0]?.[0]).toMatchObject({
+      body: {
+        title: "NEVER Use Hephaestus with Non-GPT",
+        variant: "warning",
+      },
+    })
+  })
+
   test("does not show toast when hephaestus uses gpt model", async () => {
     // given - hephaestus with gpt model
-    const showToast = spyOn({ fn: async () => ({}) }, "fn")
+    const showToast = spyOn({ fn: async (_input: unknown) => ({}) }, "fn")
     const hook = createNoHephaestusNonGptHook({
       client: { tui: { showToast } },
     } as any)
@@ -72,7 +103,7 @@ describe("no-hephaestus-non-gpt hook", () => {
 
   test("does not show toast for non-hephaestus agent", async () => {
     // given - sisyphus with claude model (non-gpt)
-    const showToast = spyOn({ fn: async () => ({}) }, "fn")
+    const showToast = spyOn({ fn: async (_input: unknown) => ({}) }, "fn")
     const hook = createNoHephaestusNonGptHook({
       client: { tui: { showToast } },
     } as any)
@@ -95,7 +126,7 @@ describe("no-hephaestus-non-gpt hook", () => {
     // given - session agent saved as hephaestus
     _resetForTesting()
     updateSessionAgent("ses_4", HEPHAESTUS_DISPLAY)
-    const showToast = spyOn({ fn: async () => ({}) }, "fn")
+    const showToast = spyOn({ fn: async (_input: unknown) => ({}) }, "fn")
     const hook = createNoHephaestusNonGptHook({
       client: { tui: { showToast } },
     } as any)
diff --git a/src/plugin/hooks/create-session-hooks.ts b/src/plugin/hooks/create-session-hooks.ts
index daa4e12e0..daa5e4ff5 100644
--- a/src/plugin/hooks/create-session-hooks.ts
+++ b/src/plugin/hooks/create-session-hooks.ts
@@ -232,7 +232,10 @@ export function createSessionHooks(args: {
     : null
 
   const noHephaestusNonGpt = isHookEnabled("no-hephaestus-non-gpt")
-    ? safeHook("no-hephaestus-non-gpt", () => createNoHephaestusNonGptHook(ctx))
+    ? safeHook("no-hephaestus-non-gpt", () =>
+      createNoHephaestusNonGptHook(ctx, {
+        allowNonGptModel: pluginConfig.agents?.hephaestus?.allow_non_gpt_model,
+      }))
     : null
 
   const questionLabelTruncator = isHookEnabled("question-label-truncator")