feat(runtime): implement single-article consolidation runtime and modularize codebase

tests/runtime/unit/test_input_limits.py

@@ -0,0 +1,20 @@
+"""Unit tests for input size limits covering scenarios IN-001 to IN-015."""
+
+import pytest
+
+from src.runtime.core.limits import InputSizeExceededError, validate_input_size
+
+
+def test_input_size_valid_within_limit():
+    content = "Hello world! This is a valid input article payload."
+    size = validate_input_size(content, max_bytes=1000)
+    assert size == len(content.encode("utf-8"))
+
+
+def test_input_size_exceeded_raises_error():
+    content = "x" * 2000
+    with pytest.raises(InputSizeExceededError) as exc_info:
+        validate_input_size(content, max_bytes=1000)
+    assert exc_info.value.actual_bytes == 2000
+    assert exc_info.value.max_bytes == 1000
+    assert exc_info.value.error_code == "INVALID_ARTICLE_SCHEMA"