Accept a pending invite by its one-time code (no team scope: the caller is not a member yet). The row flips invited to active and binds the signed-in account; already active for the same account answers already_accepted true; a code redeemed by another account is 409 invitation_already_redeemed, an expired one 409 invitation_expired, an unknown one 404. Then call /auth/refresh: the token held was minted before the membership existed.

Contract:

• MCP tool accept_team_member_invitation, registry package mcp.id/team_members, mount id.identity.
• Operation action, response envelope action.
• Flags: none.