chore: initialize monorepo with project scaffolding, configs, and CI setup

apps/blockchain-node/src/aitbc_chain/main.py

@@ -0,0 +1,72 @@
+from __future__ import annotations
+
+import asyncio
+from contextlib import asynccontextmanager
+from typing import Optional
+
+from .config import settings
+from .consensus import PoAProposer, ProposerConfig
+from .database import init_db, session_scope
+from .logging import get_logger
+
+logger = get_logger(__name__)
+
+
+class BlockchainNode:
+    def __init__(self) -> None:
+        self._stop_event = asyncio.Event()
+        self._proposer: Optional[PoAProposer] = None
+
+    async def start(self) -> None:
+        logger.info("Starting blockchain node", extra={"chain_id": settings.chain_id})
+        init_db()
+        self._start_proposer()
+        try:
+            await self._stop_event.wait()
+        finally:
+            await self._shutdown()
+
+    async def stop(self) -> None:
+        logger.info("Stopping blockchain node")
+        self._stop_event.set()
+        await self._shutdown()
+
+    def _start_proposer(self) -> None:
+        if self._proposer is not None:
+            return
+
+        proposer_config = ProposerConfig(
+            chain_id=settings.chain_id,
+            proposer_id=settings.proposer_id,
+            interval_seconds=settings.block_time_seconds,
+        )
+        self._proposer = PoAProposer(config=proposer_config, session_factory=session_scope)
+        asyncio.create_task(self._proposer.start())
+
+    async def _shutdown(self) -> None:
+        if self._proposer is None:
+            return
+        await self._proposer.stop()
+        self._proposer = None
+
+
+@asynccontextmanager
+async def node_app() -> asyncio.AbstractAsyncContextManager[BlockchainNode]:  # type: ignore[override]
+    node = BlockchainNode()
+    try:
+        yield node
+    finally:
+        await node.stop()
+
+
+def run() -> None:
+    asyncio.run(_run())
+
+
+async def _run() -> None:
+    async with node_app() as node:
+        await node.start()
+
+
+if __name__ == "__main__":  # pragma: no cover
+    run()