We compute the full cosmic microwave background temperature bispectrum generated by nonlinearities after single-field inflation. By integrating the photon temperature at second order along a perturbed geodesic in Newtonian gauge, we derive an expression for the observed temperature fluctuations that, for the first time, clarifies the separation of the gravitational lensing and time-delay effects from the purely second-order contributions. We then use the second-order Boltzmann code CosmoLib2nd to calculate these contributions and their bispectrum. Including the perturbations in the photon path, the numerically computed bispectrum exactly matches the expected squeezed limit. Moreover, the analytic squeezed-limit formula reproduces well the signal-to-noise ratio and shape of the full bispectrum, potentially facilitating the subtraction of the bias induced by second-order effects. For a cosmic-variance limited experiment with $l_{\max }=2000$, the bias on a local signal is $f_{\mathrm{NL}}^{\text{loc}}=0.73$ negligible for equilateral and orthogonal signals. The signal-to-noise ratio is unity at $l_{\max }\sim 3000$, suggesting that second-order effects may hopefully be measured in the future.

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