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

tests/runtime/integration/test_concurrency_claims.py

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+"""High-contention concurrency test verifying atomic claims with 8+ parallel workers."""
+
+from __future__ import annotations
+
+import concurrent.futures
+import threading
+from pathlib import Path
+from typing import List
+
+from src.runtime.storage.sqlite_store import SQLiteStore
+
+
+def test_concurrent_claims_with_8_workers(tmp_path: Path):
+    """Executes 8 parallel threads attempting to claim the same article fingerprint simultaneously.
+
+    Asserts:
+    1. Exactly 1 worker successfully obtains the claim and transitions to completed_text.
+    2. 7 workers receive active_claim or reuse existing result without duplicate writes.
+    3. Zero SQLite deadlock / database locked errors occur.
+    """
+    db_path = tmp_path / "test_concurrency.db"
+    store = SQLiteStore(db_path)
+    fingerprint = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
+
+    barrier = threading.Barrier(8)
+    results: List[str] = []
+    lock = threading.Lock()
+
+    def worker_action(worker_id: int):
+        # Synchronize all 8 workers at the starting line
+        barrier.wait()
+        worker_store = SQLiteStore(db_path)
+        try:
+            is_new, record = worker_store.claim_or_get_execution(
+                fingerprint=fingerprint,
+                source_url="https://example.com/test",
+                selected_extractor="trafilatura",
+                config_version="1.0.0",
+            )
+            with lock:
+                results.append(f"worker_{worker_id}:{'claimed' if is_new else 'reused'}")
+            if is_new:
+                # Worker simulates processing and records completion
+                worker_store.record_transition(
+                    fingerprint,
+                    "completed_text",
+                    reason="Completed by winner worker",
+                    extra_fields={"final_status": "completed_text"},
+                )
+        except Exception as e:
+            with lock:
+                results.append(f"worker_{worker_id}:error:{e}")
+
+    with concurrent.futures.ThreadPoolExecutor(max_workers=8) as executor:
+        futures = [executor.submit(worker_action, i) for i in range(8)]
+        concurrent.futures.wait(futures)
+
+    # Exactly 1 claimed
+    claimed_count = sum(1 for r in results if ":claimed" in r)
+    assert claimed_count == 1, f"Expected exactly 1 claim, got: {results}"
+
+    # Final state in DB must be completed_text
+    final_record = store.get_execution(fingerprint)
+    assert final_record is not None
+    assert final_record["current_status"] == "completed_text"