fix(gate): stop masking backend errors + rescue thinking-model prompt selection

Two independent, live-reproduced causes of "Smart prompt-selection unavailable (LLM response did not contain valid selection JSON)" in the gate: - Cause B (openai.ts request): the response handler JSON.parsed the body with no res.statusCode check, so a LiteLLM/vLLM HTTP 500 ("Connection error") parsed as an empty completion and surfaced as generic "bad JSON", masking backend-down. Now reject on status >= 400 with "OpenAI HTTP <status>: <body>" so the selector reports the true degradedReason. - Cause A (parseResponse + selector budget): a reasoning model (qwen3-thinking) spends its whole 1024-token budget in reasoning_content and emits content=null, so the {selectedNames} JSON never appears. parseResponse now falls back to reasoning_content (incl. provider_specific_fields) when content is empty, and the selector budget is raised 1024 -> 4000 (env MCPCTL_GATE_SELECT_MAX_TOKENS) so thinking + the JSON answer both fit. Note: mcpd's chat path got a reasoning_content fallback in PR #67; this is the separate mcplocal gate-selection provider, which never did. Tests: openai-provider (500 rejects, reasoning_content capture/preference). mcplocal suite green (749). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-23 22:10:08 +01:00
parent f614e9bb98
commit 9dbd2f175d
3 changed files with 110 additions and 2 deletions
--- a/src/mcplocal/tests/openai-provider.test.ts
+++ b/src/mcplocal/tests/openai-provider.test.ts
@@ -0,0 +1,74 @@
+/**
+ * OpenAiProvider — transport-error surfacing and reasoning_content capture.
+ *
+ * Covers the two gate prompt-ranking failure modes reproduced live 2026-07-23:
+ *  - a LiteLLM/vLLM HTTP 500 must reject (not parse as an empty completion),
+ *  - a reasoning ("thinking") model that emits its answer under
+ *    reasoning_content with content=null must still yield that text.
+ */
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+
+let mockStatus = 200;
+let mockBody = '{}';
+
+vi.mock('node:http', () => {
+  const request = vi.fn((_opts: unknown, cb?: unknown) => {
+    const res = {
+      statusCode: mockStatus,
+      on: (event: string, handler: (d?: unknown) => void) => {
+        if (event === 'data') handler(Buffer.from(mockBody));
+        if (event === 'end') handler();
+        return res;
+      },
+    };
+    if (typeof cb === 'function') (cb as (r: unknown) => void)(res);
+    return { on: vi.fn().mockReturnThis(), write: vi.fn(), end: vi.fn() };
+  });
+  return { default: { request }, request };
+});
+
+const { OpenAiProvider } = await import('../src/providers/openai.js');
+
+function provider(): InstanceType<typeof OpenAiProvider> {
+  return new OpenAiProvider({ apiKey: 'k', baseUrl: 'http://localhost:9' });
+}
+
+describe('OpenAiProvider transport + reasoning handling', () => {
+  beforeEach(() => {
+    mockStatus = 200;
+    mockBody = '{}';
+  });
+
+  it('rejects on HTTP >= 400 with the status + body (not a masked empty completion)', async () => {
+    mockStatus = 500;
+    mockBody = JSON.stringify({ error: { message: 'litellm.InternalServerError: Connection error' } });
+    await expect(
+      provider().complete({ messages: [{ role: 'user', content: 'hi' }], maxTokens: 8 }),
+    ).rejects.toThrow(/OpenAI HTTP 500/);
+  });
+
+  it('falls back to reasoning_content when content is null (thinking model)', async () => {
+    mockBody = JSON.stringify({
+      choices: [{ message: { content: null, reasoning_content: '{"selectedNames":["x"]}' }, finish_reason: 'length' }],
+    });
+    const r = await provider().complete({ messages: [{ role: 'user', content: 'hi' }], maxTokens: 8 });
+    expect(r.content).toContain('selectedNames');
+    expect(r.finishReason).toBe('length');
+  });
+
+  it('reads reasoning_content from provider_specific_fields too', async () => {
+    mockBody = JSON.stringify({
+      choices: [{ message: { content: '', provider_specific_fields: { reasoning_content: 'thought-answer' } } }],
+    });
+    const r = await provider().complete({ messages: [{ role: 'user', content: 'hi' }], maxTokens: 8 });
+    expect(r.content).toBe('thought-answer');
+  });
+
+  it('prefers real content over reasoning_content when both are present', async () => {
+    mockBody = JSON.stringify({
+      choices: [{ message: { content: 'real', reasoning_content: 'thinking' }, finish_reason: 'stop' }],
+    });
+    const r = await provider().complete({ messages: [{ role: 'user', content: 'hi' }], maxTokens: 8 });
+    expect(r.content).toBe('real');
+  });
+});