Port from openai/codex#31188: a parse failure in a policy-bearing config
file must not silently replace the effective policy with an empty/default
one. Codex's load_exec_policy_with_warning replaced the whole exec policy
with Policy::empty() when a .rules file failed to parse, silently dropping
managed prompt/forbidden rules; the fix preserves the managed policy while
still warning.
Hermes had the same bug shape in load_config(): a YAML parse error made
_load_config_impl() fall through to DEFAULT_CONFIG, dropping every user
override — including approvals.deny rules, which are documented to block
commands even under --yolo. In a long-running gateway, a user mid-editing
config.yaml into broken YAML silently disarmed their own deny rules on the
next load.
Now, when the process has a last successfully loaded config for that path
(_LAST_EXPANDED_CONFIG_BY_PATH), a parse failure keeps serving it (cached
under the corrupt file's signature so the broken file isn't re-parsed) and
the warning says edits are being ignored until the YAML is fixed. Fresh
processes with no last-known-good keep the existing DEFAULT_CONFIG
fallback and warning.
E2E-verified: deny rule 'curl*evil.com*' still blocks after mid-process
corruption; fixed file reloads normally; fresh-process fallback unchanged.
Teknium
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