One Code to Fit Them All: Forward-Folding AGN Spectra Over 11 Energy Decades with Gammapy

Most modern studies of Active Galactic Nuclei (AGN) rely on broadband spectral analyses to constrain the plethora of particle acceleration and emission processes. Traditional analysis methods are often hindered by the use of proprietary tools tailored for each participating instrument, making it challenging to integrate multi-wavelength data in a consistent, reproducible, and statistically correct way. In this work, we present a unified framework using the open-source tool gammapy to perform a forward-folding spectral analysis of AGN data from the optical to gamma-rays (over 11 decades in energy), enabling the full incorporation of instrument response functions and astrophysical backgrounds, while reducing biases associated with the traditional flux point analysis. It also offers a flexible and compact data format to store and distribute the data and telescope information. We demonstrate its capabilities with data from the quasars OP 313 and 4C +27.50, which underwent flaring activity during 2024. Our analysis includes optical data from the Liverpool Telescope, UV data from {\it Swift}-UVOT, X-ray data from {\it Swift}-XRT and NuSTAR, and gamma-ray data from {\it Fermi}-LAT. We validate the analysis against native tools for each instrument, and discuss the prospects for future multi-wavelength and time-domain astrophysical studies of AGN.