python3 is used unguarded by the AI session helpers and (guarded) by the
paru/yay log cleaner, but was absent from the dependency catalog and docs.
uv does not provide python3 on PATH, and Arch's base omits it, so it is
tracked separately rather than assumed via uv.
- Add python3 (recommended tier, pm: python) to _fish_deps_catalog.fish
- Guard python3 calls in save_claude_session/save_antigravity_session with
`type -q python3`, emitting valid empty JSON when absent (Convention §6)
- Document python3 in docs/fish-config.md (§5.6 tiers + catalog entry)
rootiest
681a48f3c5
