From 895eff09b01ce524a4878a65096adfd5191b7d78 Mon Sep 17 00:00:00 2001
From: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>
Date: Mon, 24 Aug 2026 22:37:47 -0500
Subject: [PATCH] fix(ai): classify missing chat finish reasons as incomplete
 (#44864)

---
 packages/ai/src/protocols/openai-chat.ts              | 11 ++++++++++-
 .../ai/test/provider/openai-compatible-chat.test.ts   |  1 +
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/packages/ai/src/protocols/openai-chat.ts b/packages/ai/src/protocols/openai-chat.ts
index 2821db8cf87..4770a301838 100644
--- a/packages/ai/src/protocols/openai-chat.ts
+++ b/packages/ai/src/protocols/openai-chat.ts
@@ -7,6 +7,7 @@ import { HttpTransport } from "../route/transport/index.js"
 import { Protocol } from "../route/protocol.js"
 import {
   AIError,
+  InvalidProviderOutputReason,
   LLMEvent,
   ProviderInternalReason,
   UnknownProviderReason,
@@ -1046,7 +1047,15 @@ const step = (state: ParserState, event: OpenAIChatEvent) =>
 
 const finishEvents = Effect.fn("OpenAIChat.finishEvents")(function* (state: ParserState) {
   if (state.finishReason === undefined && state.requireFinishReason)
-    return yield* ProviderShared.eventError(ADAPTER, "OpenAI Chat stream ended without finish_reason")
+    return yield* new AIError({
+      module: ADAPTER,
+      method: "stream",
+      reason: new InvalidProviderOutputReason({
+        classification: "incomplete-stream",
+        message: "OpenAI Chat stream ended without finish_reason",
+        route: ADAPTER,
+      }),
+    })
   const events: LLMEvent[] = []
   const toolCallEvents =
     state.finishReason === undefined && Object.keys(state.tools).length > 0
diff --git a/packages/ai/test/provider/openai-compatible-chat.test.ts b/packages/ai/test/provider/openai-compatible-chat.test.ts
index 01144c7e26c..c4108d1b402 100644
--- a/packages/ai/test/provider/openai-compatible-chat.test.ts
+++ b/packages/ai/test/provider/openai-compatible-chat.test.ts
@@ -362,6 +362,7 @@ describe("OpenAI-compatible Chat route", () => {
 
       expect(error.reason).toMatchObject({
         _tag: "InvalidProviderOutput",
+        classification: "incomplete-stream",
         message: "OpenAI Chat stream ended without finish_reason",
       })
     }),