_set_nested unconditionally replaced any non-dict value with an empty
dict when walking the dotted path, which silently destroyed list-typed
config nodes the moment someone set a value with a numeric index
(e.g. 'hermes config set custom_providers.0.api_key NEW'). Any sibling
entries and any fields inside the targeted entry that the user didn't
write were lost.
Fix:
- _set_nested now detects list nodes and navigates by numeric index,
and preserves both dicts AND lists at intermediate positions (scalars
are still replaced so bare-scalar -> nested overrides keep working).
- set_config_value drops its duplicated navigation logic and calls
_set_nested instead -- single source of truth for the rules.
Regression tests (tests/hermes_cli/test_set_config_value.py):
- test_indexed_set_preserves_sibling_list_entries -- exact #17876 repro
- test_indexed_set_preserves_non_targeted_fields -- inner-dict fields survive
- test_deeper_nesting_through_list -- dict -> list -> dict -> scalar path
35/35 existing + new tests pass.
E2E-verified with the issue's repro against a real on-disk config.yaml --
list stays a list, entry 0 updated, entry 1 intact.
Closes#17876
b50bc13ef9