= Solution
Choose Hermitian Lie-algebra generators satisfying $[T^a,T^b]=if^{abc}T^c$, with real totally antisymmetric <Lie algebra structure constants> in an orthonormal compact-group basis. The <Adjoint representation> generators are $(T^b_{\mathrm{ad}})_{ac}=-if^{bac}$. For a canonically normalized <Yang-Mills action>, the coupling is in the <gauge covariant derivative>, rather than an overall $1/g^2$ kinetic prefactor. The conventions $D_\mu=\partial_\mu-igA_\mu^bT^b_{\mathrm{ad}}$ give
$$
\boxed{(\not D\psi)^a=\gamma^\mu\left(\partial_\mu\psi^a+gf^{abc}A_\mu^b\psi^c\right).}
$$
Equivalently, for the Lie-algebra-valued spinor, $D_\mu\psi=\partial_\mu\psi-ig[A_\mu,\psi]$. This is the <adjoint covariant derivative> with the Hermitian-generator and explicit-coupling convention specified. Changing the sign convention for $D$ changes the accompanying gauge-transformation convention consistently.
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