  Measurements of chemical abundances in high-$z$ star-forming (SF) galaxies
place important constraints on the enrichment histories of galaxies and the
physical conditions in the early universe. JWST is beginning to enable direct
chemical abundance measurements in galaxies at $z$$>$2 via the detection of the
faint T$_e$-sensitive auroral line [O III]$\lambda$4364. However, abundances of
other elements (e.g., S and Ar) in high-$z$ galaxies remain unconstrained due
to a lack of T$_e$ data and wavelength coverage. Here, we present multiple
direct abundances in Q2343-D40, a galaxy at $z=$2.9628$\pm$0.0001 observed with
JWST/NIRSpec as part of the CECILIA program. We report the first simultaneous
measurement of T$_e$[O III] and T$_e$[S III] in a high-$z$ galaxy, finding good
agreement with the temperature trends in local SF systems. We measure a
gas-phase metallicity of 12+log(O/H) $=8.07\pm0.06$, and the N/O abundance,
log(N/O) $=-1.37\pm0.21$, is indicative of primary nucleosynthesis. The S/O and
Ar/O relative abundances, log(S/O)$=-1.88\pm0.10$ and log(Ar/O)$=-2.80\pm0.12$,
are both $>$0.3 dex lower than the solar ratios. However, the relative
Ar$^{2+}$/S$^{2+}$ abundance is consistent with the solar ratio, suggesting
that the relative S-to-Ar abundance does not evolve significantly with
redshift. Recent nucleosynthesis models find that a significant amount of S and
Ar are produced in Type Ia supernovae, such that the S/O and Ar/O abundances in
Q2343-D40 could be the result of predominantly core-collapse supernovae
enrichment. Future JWST observations of high-$z$ galaxies will uncover whether
S/O and Ar/O are sensitive to the timescales of these different enrichment
mechanisms.
