fix(llm): make connect timeout configurable

Use a configurable LLM_CONNECT_TIMEOUT for call and stream connect budgets instead of the previous hard-coded 3s default.

tests/test_llm_core_connect_timeout.py

@@ -0,0 +1,57 @@
+"""Regression tests for the configurable LLM connect timeout.
+
+Background: chat uses the streaming path, which (unlike llm_call) does not retry
+a connect error -- it marks the host and emits a 503 immediately. With the old
+hard-coded connect=3.0s, a brief blip on the first (cold) connect of an idle
+chat to an offshore/public endpoint surfaced as an intermittent 503 that cleared
+on resend. The connect budget is now LLMConfig.CONNECT_TIMEOUT (env
+LLM_CONNECT_TIMEOUT), applied via _call_timeout/_stream_timeout helpers.
+"""
+import importlib
+import httpx
+import pytest
+
+from src import llm_core
+from src.llm_core import LLMConfig, _call_timeout, _stream_timeout
+
+
+def test_default_connect_timeout_is_widened_not_three():
+    # Regression guard: must not regress to the old too-tight 3.0s default.
+    assert LLMConfig.CONNECT_TIMEOUT >= 8.0
+    assert LLMConfig.CONNECT_TIMEOUT != 3.0
+    assert LLMConfig.CONNECT_TIMEOUT == 10.0
+
+
+def test_call_timeout_uses_config_connect_and_passes_read():
+    t = _call_timeout(45)
+    assert isinstance(t, httpx.Timeout)
+    assert t.connect == LLMConfig.CONNECT_TIMEOUT
+    assert t.read == 45.0
+    assert t.write == 10.0
+    assert t.pool == 5.0
+
+
+def test_stream_timeout_uses_config_connect_and_passes_read():
+    t = _stream_timeout(300)
+    assert isinstance(t, httpx.Timeout)
+    assert t.connect == LLMConfig.CONNECT_TIMEOUT
+    assert t.read == 300.0
+    assert t.write == 30.0
+    assert t.pool == 5.0
+
+
+def test_helpers_are_config_driven(monkeypatch):
+    # Helpers read LLMConfig at call time, so ops can tune without code edits.
+    monkeypatch.setattr(LLMConfig, "CONNECT_TIMEOUT", 4.5)
+    assert _call_timeout(30).connect == 4.5
+    assert _stream_timeout(30).connect == 4.5
+
+
+def test_env_override_is_honoured(monkeypatch):
+    monkeypatch.setenv("LLM_CONNECT_TIMEOUT", "6.5")
+    reloaded = importlib.reload(llm_core)
+    try:
+        assert reloaded.LLMConfig.CONNECT_TIMEOUT == 6.5
+    finally:
+        monkeypatch.delenv("LLM_CONNECT_TIMEOUT", raising=False)
+        importlib.reload(llm_core)  # restore module-level default for other tests