117 lines
3.5 KiB
Python
117 lines
3.5 KiB
Python
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"""FastAPI dependencies and app lifespan.
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Owns the ToolBox singleton, the compiled LangGraph workflow, and the
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recursion limit. Construction happens once at app startup; teardown is a
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no-op because OntoCast tools don't currently expose a close hook.
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Why a module-level holder instead of `app.state`:
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The /process route is async and may be entered concurrently. A simple
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dict on `app.state` works, but pulling the ToolBox through a typed
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dependency function makes the contract explicit and gives every route
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the same view of "what tools and what workflow are available right now".
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"""
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from __future__ import annotations
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import asyncio
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import logging
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import sys
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from dataclasses import dataclass
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from pathlib import Path
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# Make vendored OntoCast importable. (Same trick as platform/config.py.)
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_REPO_ROOT = Path(__file__).resolve().parents[2]
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_VENDORED_ONTOCAST = _REPO_ROOT / "vendored" / "ontocast"
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if str(_VENDORED_ONTOCAST) not in sys.path:
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sys.path.insert(0, str(_VENDORED_ONTOCAST))
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from langchain_core.runnables import RunnableConfig # noqa: E402
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from langgraph.graph.state import CompiledStateGraph # noqa: E402
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from ontocast.cli.serve import calculate_recursion_limit # noqa: E402
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from ontocast.config import ServerConfig # noqa: E402
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from ontocast.stategraph import create_agent_graph # noqa: E402
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from ontocast.toolbox import ToolBox # noqa: E402
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import importlib
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platform_config = importlib.import_module("platform.config")
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logger = logging.getLogger(__name__)
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@dataclass
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class AppContext:
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"""Immutable holder for objects that live as long as the FastAPI app."""
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settings: "platform_config.PlatformSettings"
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tools: ToolBox
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workflow: CompiledStateGraph
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server_config: ServerConfig
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recursion_limit: int
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_context: AppContext | None = None
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async def initialize_app_context(
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settings: "platform_config.PlatformSettings | None" = None,
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*,
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head_chunks: int | None = None,
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) -> AppContext:
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"""Build ToolBox + workflow once. Idempotent on repeat calls."""
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global _context
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if _context is not None:
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return _context
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settings = settings or platform_config.load_settings()
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ontocast_config = platform_config.build_ontocast_config(settings)
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tools = ToolBox(ontocast_config)
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# OntoCast's ToolBox.initialize is async; do it here so a request doesn't
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# have to pay the cost.
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await tools.initialize()
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workflow = create_agent_graph(tools)
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server_config = ontocast_config.server
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recursion_limit = calculate_recursion_limit(head_chunks, server_config)
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_context = AppContext(
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settings=settings,
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tools=tools,
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workflow=workflow,
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server_config=server_config,
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recursion_limit=recursion_limit,
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)
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logger.info(
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"App context initialized "
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f"(phase={int(settings.phase)}, backend={settings.storage_backend}, "
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f"working_dir={settings.working_directory})"
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)
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return _context
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def get_app_context() -> AppContext:
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"""FastAPI dependency. Raises clearly if the lifespan never ran."""
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if _context is None:
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raise RuntimeError(
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"AppContext not initialized — the app lifespan must run "
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"`initialize_app_context()` before serving requests."
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)
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return _context
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def reset_app_context_for_testing() -> None:
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"""Test-only: drop the cached context so each test can rebuild it."""
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global _context
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_context = None
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__all__ = [
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"AppContext",
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"RunnableConfig",
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"get_app_context",
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"initialize_app_context",
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"reset_app_context_for_testing",
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]
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