Context : RX J1713.7–3946 is the brightest shell-type Supernova remnant ( SNR ) of the TeV \gamma -ray sky .
Earlier Fermi-LAT results on low-energy \gamma -ray emission suggested that , despite large uncertainties in the background determination , the spectrum is inconsistent with a hadronic origin .

Aims : We update the GeV-band spectra using improved estimates for the diffuse galactic \gamma -ray emission and more than doubled data volume .
We further investigate the viability of hadronic emission models for RX J1713.7–3946 .

Methods : We produced a high-resolution map of the diffuse Galactic \gamma -ray background corrected for the HI self-absorption and used it in the analysis of more than 5 years worth of Fermi-LAT data .
We used hydrodynamic scaling relations and a kinetic transport equation to calculate the acceleration and propagation of cosmic-rays in SNR .
We then determined spectra of hadronic \gamma -ray emission from RX J1713.7–3946 , separately for the SNR interior and the cosmic-ray precursor region of the forward shock , and computed flux variations that would allow to test the model with observations .

Results : We find that RX J1713.7–3946 is now detected by Fermi-LAT with very high statistical significance , and the source morphology is best described by that seen in the TeV band .
The measured spectrum of RX J1713.7–3946 is hard with index \gamma = 1.53 \pm 0.07 , and the integral flux above 500 MeV is F = ( 5.5 \pm 1.1 ) \times 10 ^ { -9 } photons cm ^ { -2 } s ^ { -1 } .
We demonstrate that scenarios based on hadronic emission from the cosmic-ray precursor region are acceptable for RX J1713.7–3946 , and we predict a secular flux increase at a few hundred GeV at the level of around 15 % over 10 years , which may be detectable with the upcoming CTA observatory .

Conclusions :