feat: add worker job-claim logic

worker/lyra_worker/claim.py

@@ -0,0 +1,34 @@
+import psycopg
+
+
+def claim_next(conn: psycopg.Connection) -> str | None:
+    """Atomically claim the oldest queued job. Returns its id or None."""
+    with conn.cursor() as cur:
+        cur.execute(
+            """
+            SELECT id FROM "Job"
+            WHERE state = 'requested'
+            ORDER BY "createdAt" ASC
+            FOR UPDATE SKIP LOCKED
+            LIMIT 1
+            """
+        )
+        row = cur.fetchone()
+        if row is None:
+            conn.rollback()
+            return None
+        job_id = row[0]
+        cur.execute(
+            """
+            UPDATE "Job"
+            SET state = 'matching',
+                "currentStage" = 'match',
+                "claimedAt" = now(),
+                attempts = attempts + 1,
+                "updatedAt" = now()
+            WHERE id = %s
+            """,
+            (job_id,),
+        )
+    conn.commit()
+    return job_id

worker/lyra_worker/db.py

@@ -0,0 +1,8 @@
+import os
+
+import psycopg
+
+
+def connect() -> psycopg.Connection:
+    dsn = os.environ["DATABASE_URL"]
+    return psycopg.connect(dsn)