From ca1bde5e18481de48a4220d288dc57506379f83b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=9B=BE=E6=96=87=E9=94=8B0668000834?=
 <zeng.wenfeng@xydigit.com>
Date: Fri, 13 Mar 2026 09:15:55 +0800
Subject: [PATCH] fix(providers): classify transport errors as retriable for
 fallback chain

Add transport-level connection error patterns to error classifier:
- connection reset by peer
- connection refused
- no route to host
- unexpected eof
- broken pipe
- network is unreachable
- connection closed
- tls handshake errors
- read/write tcp errors

These errors are now classified as FailoverTimeout (retriable), allowing
the fallback chain to continue instead of aborting on unclassified errors.

Fixes #1419 (part 1)
---
 pkg/providers/error_classifier.go | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/pkg/providers/error_classifier.go b/pkg/providers/error_classifier.go
index fd9bf1e81..35af3b103 100644
--- a/pkg/providers/error_classifier.go
+++ b/pkg/providers/error_classifier.go
@@ -50,6 +50,20 @@ var (
 		substr("context deadline exceeded"),
 	}
 
+	// Transport-level connection errors that should trigger fallback
+	transportErrorPatterns = []errorPattern{
+		substr("connection reset by peer"),
+		substr("connection refused"),
+		substr("no route to host"),
+		substr("unexpected eof"),
+		substr("broken pipe"),
+		substr("network is unreachable"),
+		substr("connection closed"),
+		substr("tls handshake"),
+		substr("read tcp"),
+		substr("write tcp"),
+	}
+
 	billingPatterns = []errorPattern{
 		rxp(`\b402\b`),
 		substr("payment required"),
@@ -195,6 +209,9 @@ func classifyByMessage(msg string) FailoverReason {
 	if matchesAny(msg, timeoutPatterns) {
 		return FailoverTimeout
 	}
+	if matchesAny(msg, transportErrorPatterns) {
+		return FailoverTimeout // Transport errors treated as timeout (retriable)
+	}
 	if matchesAny(msg, authPatterns) {
 		return FailoverAuth
 	}