bvandeusenandClaude Opus 4.7
3579db2f06
Adds mcp._context.current_user_id() backed by a ContextVar. The ASGI auth middleware sets it before dispatching to FastMCP and resets it on the way out, so tool handlers can read the acting user without re-parsing the request scope. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
21 lines
732 B
Python
21 lines
732 B
Python
"""Per-request MCP context.
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The ASGI middleware (mcp/server.py) populates `_user_id_ctx` from
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scope['fable_user_id'] before dispatching to FastMCP tool handlers.
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Tool functions then call `current_user_id()` to retrieve it.
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Tools must never fall back to a default user — `current_user_id()` raises
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if called outside a properly-authed MCP request.
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"""
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from contextvars import ContextVar
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_user_id_ctx: ContextVar[int | None] = ContextVar("fable_mcp_user_id", default=None)
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def current_user_id() -> int:
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"""Return the user_id for the in-flight MCP request. Raises if unset."""
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uid = _user_id_ctx.get()
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if uid is None:
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raise RuntimeError("no MCP user context — request was not bearer-authed")
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return uid
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