The terminal-command guard path loaded config 2-3x per invocation via
load_config(), which pays a defensive deepcopy of the entire config on
every call (~356us of the ~376us warm-cache cost measured on a real
config.yaml). All six swapped call sites were audited read-only — every
caller takes scalar reads or iterates the returned structures; none
mutate (the save path at save_permanent_allowlist keeps load_config) —
so they now use load_config_readonly(), the API built for exactly this
(precedent: #74211, #74322; the one unsafe-site lesson from #56085's
salvage is covered by the mutation audit and a cache-integrity test).
Measured (real config.yaml, warm cache): load_config 376.0us ->
load_config_readonly 19.9us (18.9x); full guard pass
check_all_command_guards('ls -la','local') 930.7us -> 241.8us (3.85x).
Tests: new test_approval_config_readonly.py drives the real functions
against a temp HERMES_HOME — readonly call counts per function, a
no-deepcopy pin for the full guard pass, and cache-identity/integrity
checks. Existing test mocks retargeted from load_config to
load_config_readonly (same injection intent). Note: 6
test_approval_mode_parity failures are pre-existing ordering flakes —
identical with the change stashed on clean main.
spfcraze