refactor(config): keep concurrency out of DEFAULT_CONFIG (align with other optional knobs)

Every other optional tuning knob (timeout, extra_headers, litellm,
entity_types, parallel_tool_calls) is resolved via its resolver's .get()
and lives only in config.yaml.example, not DEFAULT_CONFIG — which holds just
the core keys openkb init writes (model, language, pageindex_threshold).
concurrency was the lone exception; resolve_concurrency already reads it via
.get(), so the DEFAULT_CONFIG entry was redundant. Remove it for consistency.

Author: KylinMountain

openkb/config.py

@@ -17,13 +17,6 @@
     "model": "gpt-5.4",
     "language": "en",
     "pageindex_threshold": 20,
-    # Cap on concurrent LLM calls OpenKB makes during ingest — both PageIndex's
-    # indexing of a long document and OpenKB's own concept/entity compilation.
-    # These never run concurrently with each other for the same document, so
-    # one knob covers both. None = each stage applies its own built-in default.
-    # Lower it if you hit provider rate limits or "too many open files"; raise
-    # it to go faster.
-    "concurrency": None,
 }
 
 # Default entity-type vocabulary. Overridable per-KB via the optional

tests/test_config.py

@@ -136,8 +136,12 @@ def test_default_config_values():
     assert DEFAULT_CONFIG["pageindex_threshold"] == 20
 
 
-def test_concurrency_defaults_to_none():
-    assert DEFAULT_CONFIG["concurrency"] is None
+def test_concurrency_not_in_default_config():
+    # Like the other optional tuning knobs (timeout, extra_headers,
+    # parallel_tool_calls), concurrency stays out of DEFAULT_CONFIG —
+    # resolve_concurrency reads it via .get(), so an absent key resolves to
+    # None without relying on load_config's merge.
+    assert "concurrency" not in DEFAULT_CONFIG
 
 
 def test_load_concurrency_override(tmp_path):