Phase-2 review follow-ups on the unreadable-config chokepoint work:
- hermes_cli/xai_retirement.py apply_migration() is a full-file config.yaml
rewriter (ruamel round-trip + plain open("w")) that lives outside the
atomic_yaml_write path, so the chokepoint didn't cover it. It reads the
file first (which already fails closed on an unreadable file), but add
require_readable_config_before_write() right before the write as a
backstop for the read-then-write window, and a regression test asserting
the original bytes survive an unreadable config.
- Drop the unnecessary "Path" string quotes on atomic_config_write's
annotation — Path is imported eagerly at module top, no forward ref needed.
auth.py _update_config_for_provider / _reset_config_provider intentionally
keep their standalone require_readable_config_before_write guard + bare
atomic_yaml_write: the guard must fire BEFORE the read (fail-fast) at those
read-then-write sites, and a test pins the atomic_yaml_write call. Both are
already fully guarded against the bug; routing them through the wrapper
would move the check to write time for no benefit.
Extends hermes_cli.xai_retirement with apply_migration(config_path,
issues, backup=True), used by the upcoming `hermes migrate xai`
sub-command.
Uses ruamel.yaml round-trip mode so that comments, key order,
indentation, quoting style, and scalar types are preserved on
rewrite — config.yaml is treated as a user-edited file, not a
data dump.
Behavior:
- Each issue rewrites parent[leaf] to issue.replacement
- When issue.reasoning_effort is set (non-reasoning variants
that map to grok-4.3), a sibling reasoning_effort key is
added/updated alongside the model
- Empty issues list or missing slots are no-ops (no backup,
no rewrite)
- When changes occur, a timestamped backup
(.bak-pre-migrate-xai-YYYYMMDD-HHMMSS) is written first
unless backup=False
17 unit tests cover dry-run/no-op, surgical replacement (each
slot), comment + key-order preservation, backup creation, and
idempotence (apply twice → no-op the second time).
