Addresses two concerns surfaced during PR #376 review:
1. **SSH option-injection on the host value.** The original PR uses
shlex.quote() on the remote command and added a `--` option terminator
in front of the host, but neither one stops a hostile env var like
`LAST30DAYS_YT_SSH_HOST=-oProxyCommand=...` from being read in the
first place. Tighten `_ytdlp_ssh_host()` to validate the host against
`^[a-zA-Z0-9._-]+$` (plain hostname/SSH-config-alias shape: letters,
digits, dot, underscore, hyphen). Any value that doesn't match logs a
warning to stderr and returns None, so the wrap function falls back to
local execution. The `--` terminator stays as defense-in-depth for the
case where a valid host happens to start with `-`, but the regex closes
the door on the env var reaching ssh at all.
2. **Env var naming consistency.** Existing skill-internal config knobs
spell out their domain: `LAST30DAYS_X_BACKEND`, `LAST30DAYS_X_MODEL`,
`LAST30DAYS_PLANNER_MODEL`, `LAST30DAYS_RERANK_MODEL`, etc. The module
is `youtube_yt.py`, the source key is `youtube`, the function family
is `is_youtube_*()` — `YT` was the odd abbreviation out. Rename to
`LAST30DAYS_YOUTUBE_SSH_HOST` so the variable matches the user mental
model ("route YouTube fetches via residential IP") and the codebase's
spelled-out convention.
Adds three new tests:
- test_host_alias_with_dash_prefix_is_rejected (validator rejects `-o...`)
- test_host_alias_with_shell_metacharacters_is_rejected (rejects spaces, ;, $, `, &)
- test_host_alias_validator_accepts_realistic_aliases (allows FQDNs, IPs, bare aliases)
The existing test_wrap_cmd_uses_option_terminator is rewritten to use a
valid host value (since an invalid one is now filtered upstream) and
continues to assert the `--` terminator placement as defense-in-depth.
44/44 youtube_yt tests pass (40 prior + 4 net new validator tests).
Trevin Chow
27c90504c0