更新

server/tests/DiagnosisAiAssistantStreamContractTest.php

@@ -100,11 +100,14 @@ assistantStreamExpect(
 );
 assistantStreamExpect(
     str_contains($controller, "'text' => \$delta")
-        && str_contains($controller, "'code' => 'AI_ASSISTANT_FAILED'")
+        && str_contains($controller, 'DiagnosisAiLogic::getAssistantErrorCode()')
+        && str_contains($controller, 'DiagnosisAiLogic::getError()')
         && str_contains($controller, 'ignore_user_abort(true)')
         && str_contains($controller, 'connection_aborted() === 1')
-        && !str_contains($controller, "DiagnosisAiLogic::getError()\n                ]"),
-    'delta carries text, disconnects abort upstream, and errors use a generic prompt-free payload'
+        && str_contains($logic, '!$deliveredDelta')
+        && str_contains($logic, "['UPSTREAM_REJECTED', 'INCOMPLETE_RESPONSE', 'EMPTY_RESPONSE']")
+        && str_contains($logic, 'DifyChatService::chat('),
+    'delta carries text, disconnects abort upstream, and pre-delta stream failures safely fall back once'
 );
 assistantStreamExpect(
     str_contains($logic, 'DifyChatService::chat(')

server/tests/DifyChatStreamContractTest.php

@@ -95,6 +95,37 @@ $explicitOpenAi = callDifyStreamPrivate('buildRequestSpecs', [
 difyStreamExpect(count($explicitDify) === 1 && $explicitDify[0]['protocol'] === 'dify', 'explicit Dify endpoint never changes protocol');
 difyStreamExpect(count($explicitOpenAi) === 1 && $explicitOpenAi[0]['protocol'] === 'openai', 'explicit OpenAI endpoint never changes protocol');
 
+$retryableStream = [
+    'errno' => 0,
+    'http_code' => 200,
+    'emitted' => false,
+    'upstream_error' => true,
+    'finished' => false,
+];
+difyStreamExpect(
+    callDifyStreamPrivate('shouldTryNextProtocol', [$retryableStream, true]) === true,
+    'a terminal-free stream error before any delta tries the alternate protocol'
+);
+$retryableStream['emitted'] = true;
+difyStreamExpect(
+    callDifyStreamPrivate('shouldTryNextProtocol', [$retryableStream, true]) === false,
+    'an emitted delta forbids protocol retry'
+);
+difyStreamExpect(
+    callDifyStreamPrivate('shouldTryNextProtocol', [[
+        'errno' => 0,
+        'http_code' => 400,
+    ], false]) === true,
+    'an ambiguous endpoint rejected before generation tries the alternate protocol'
+);
+difyStreamExpect(
+    callDifyStreamPrivate('shouldTryNextProtocol', [[
+        'errno' => 0,
+        'http_code' => 401,
+    ], true]) === false,
+    'credential failures are not hidden by protocol retry'
+);
+
 $difyWire = ": ping\r\n\r\n"
     . "data: {\"event\":\"message\",\"answer\":\"你\",\"message_id\":\"msg-safe\"}\r\n\r\n"
     . "data: {\"event\":\"agent_message\",\"answer\":\"好\"}\r\n\r\n"

server/tests/PrescriptionAiUpstreamContractTest.php

@@ -192,6 +192,40 @@ expectSame(false, callPrivate('shouldRetryWithoutFiles', [400, []]), 'a text-onl
 expectSame(false, callPrivate('shouldRetryWithoutFiles', [401, $capped['kept']]), 'a credential failure is not retried');
 expectSame(false, callPrivate('shouldRetryWithoutFiles', [500, $capped['kept']]), 'an upstream outage is not retried here');
 
+// 协议回退会把最初的“附件被拒”换成另一协议的状态码（Dify 400 -> OpenAI 404），
+// 降级判断必须按每次响应累计，否则去掉附件的重试永远不会发生。
+expectSame(
+    true,
+    callPrivate('isFileRejection', [['errno' => 0, 'http_code' => 400], $capped['kept']]),
+    'an attachment rejection is recognised on the response that carried it'
+);
+expectSame(
+    false,
+    callPrivate('isFileRejection', [['errno' => 0, 'http_code' => 404], $capped['kept']]),
+    'the fallback protocol 404 is not itself an attachment rejection'
+);
+expectSame(
+    true,
+    callPrivate('isFileRejection', [
+        ['errno' => 0, 'http_code' => 200, 'upstream_error' => true],
+        $capped['kept'],
+    ]),
+    'a 200 stream carrying event:error counts as an attachment rejection'
+);
+expectSame(
+    false,
+    callPrivate('isFileRejection', [
+        ['errno' => 0, 'http_code' => 200, 'upstream_error' => true],
+        [],
+    ]),
+    'a text-only request never degrades further'
+);
+expectSame(
+    false,
+    callPrivate('isFileRejection', [['errno' => 28, 'http_code' => 0], $capped['kept']]),
+    'a transport failure is not mistaken for an attachment rejection'
+);
+
 // Dify 的 inputs 必须是 JSON 对象。PHP 空数组会被编码成 []，上游以
 // invalid_param 拒绝整单——空 inputs 的调用方会 100% 失败。
 $emptyInputs = callPrivate('buildRequestSpecs', [