From 7b1923b09941131d145ffc46c2a91a644180e3ae Mon Sep 17 00:00:00 2001
From: roboomp <omp@can.ac>
Date: Mon, 3 Aug 2026 15:23:35 +0000
Subject: [PATCH] fix(ai): stop forwarding auto service tier to codex
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shouldSendServiceTier/applyOpenAIServiceTier began forwarding every tier —
including `auto` — for openai/openai-codex after PR #7376. Legacy/default
sessions resolve to {openai:"auto"}, so Codex (ChatGPT OAuth) requests now
carry service_tier:"auto", which that endpoint rejects with a 400, breaking
every turn at default settings.

Never send `auto`: it is OpenAI's implicit default, so omitting service_tier
is identical where accepted and required where the tier is rejected. Explicit
default/flex/scale/priority are unchanged.

Fixes #7517
---
 packages/ai/CHANGELOG.md                            |  4 ++++
 packages/ai/src/types.ts                            | 13 ++++++++-----
 .../ai/test/service-tier-premium-requests.test.ts   |  7 +++++--
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/packages/ai/CHANGELOG.md b/packages/ai/CHANGELOG.md
index abfe680ff..73ad730be 100644
--- a/packages/ai/CHANGELOG.md
+++ b/packages/ai/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed OpenAI-Codex (ChatGPT OAuth) requests failing with `Unsupported service_tier: auto` on default/legacy sessions. `shouldSendServiceTier` no longer forwards `auto` on the wire — it is OpenAI's implicit default, so omitting `service_tier` is equivalent, and the Codex endpoint rejects an explicit `auto`. Explicit `default`/`flex`/`scale`/`priority` are unaffected ([#7517](https://github.com/can1357/oh-my-pi/issues/7517)).
+
 ## [17.2.6] - 2026-08-03
 
 ### Added
diff --git a/packages/ai/src/types.ts b/packages/ai/src/types.ts
index 8a7cb8b18..e850eb004 100644
--- a/packages/ai/src/types.ts
+++ b/packages/ai/src/types.ts
@@ -214,16 +214,19 @@ export function resolveModelServiceTier(
 
 /**
  * True when the tier should be sent on the wire as the provider's service-tier
- * request field. OpenAI / OpenAI-Codex accept every {@link ServiceTier};
- * Google (Gemini API + Vertex) and OpenRouter accept `flex`/`priority`;
- * Fireworks Serverless realizes only its Priority serving path. Anthropic is
- * absent because it realizes `priority` via `speed: "fast"`.
+ * request field. `auto` is never forwarded — it is OpenAI's implicit default, so
+ * omitting `service_tier` is identical to requesting `auto`, and the Codex
+ * (ChatGPT OAuth) endpoint rejects an explicit `auto` outright. OpenAI /
+ * OpenAI-Codex accept every other {@link ServiceTier}; Google (Gemini API +
+ * Vertex) and OpenRouter accept `flex`/`priority`; Fireworks Serverless
+ * realizes only its Priority serving path. Anthropic is absent because it
+ * realizes `priority` via `speed: "fast"`.
  */
 export function shouldSendServiceTier(
 	serviceTier: ServiceTier | null | undefined,
 	target: Provider | ServiceTierModel | undefined,
 ): boolean {
-	if (!serviceTier) return false;
+	if (!serviceTier || serviceTier === "auto") return false;
 	const provider = typeof target === "string" ? target : target?.provider;
 	if (provider === "openai" || provider === "openai-codex") return true;
 	if (provider === "openrouter") {
diff --git a/packages/ai/test/service-tier-premium-requests.test.ts b/packages/ai/test/service-tier-premium-requests.test.ts
index c0d0119cf..96fe0a3f8 100644
--- a/packages/ai/test/service-tier-premium-requests.test.ts
+++ b/packages/ai/test/service-tier-premium-requests.test.ts
@@ -78,14 +78,17 @@ describe("resolveModelServiceTier", () => {
 });
 
 describe("shouldSendServiceTier", () => {
-	it("sends every tier on the OpenAI family and supported tiers elsewhere", () => {
+	it("sends every explicit tier on the OpenAI family, omits auto, supported tiers elsewhere", () => {
 		for (const p of ["openai", "openai-codex"] as const) {
 			expect(shouldSendServiceTier("flex", p)).toBe(true);
 			expect(shouldSendServiceTier("scale", p)).toBe(true);
 			expect(shouldSendServiceTier("priority", p)).toBe(true);
 			expect(shouldSendServiceTier("default", p)).toBe(true);
-			expect(shouldSendServiceTier("auto", p)).toBe(true);
+			// `auto` is OpenAI's implicit default and the Codex endpoint rejects it — never sent.
+			expect(shouldSendServiceTier("auto", p)).toBe(false);
 		}
+		expect(shouldSendServiceTier("auto", codex)).toBe(false);
+		expect(shouldSendServiceTier("auto", customOpenAI)).toBe(false);
 		expect(shouldSendServiceTier("flex", "openrouter")).toBe(true);
 		expect(shouldSendServiceTier("default", "openrouter")).toBe(false);
 		expect(shouldSendServiceTier("priority", customCodex)).toBe(true);