The Astro PoVs addon
A small addon that goes with the app. It does two things: it turns combat logging on when it matters, and it tells the app what the log does not say.
What it does
Astro PoVs has an addon of its own. It turns combat logging on, with Advanced Combat Logging, every time you enter a raid or a key, and turns it on again if you disconnect in the middle of a key. With it you never have to remember /combatlog again.
The app decides what to log. Your recording settings (which raids and difficulties, which keys and from what level, other dungeons) are written into the addon folder, and the addon follows them. One place to set it up.
How to install it
The easy way is from the app itself: when it cannot find the addon it offers to install it in one click, and from then on it keeps it up to date. The Addon line on its status card says whether it is there.
If you would rather use your addon manager, it is published on these sites. You get the same files.
In WowUp, search for Astro PoVs.
Its options
Its switches are in the game, under Options > AddOns > Astro PoVs or with /astropovs: automatic logging, sharing your character, sharing your chat position. Which content gets logged is decided by the app from your recording settings; change them with the game open and it asks you for a /reload. The addon never prints to your chat, never turns logging off, and sends nothing anywhere.
What it saves, and what it never does
It saves a few things the combat log never says: your character, class and spec (so a manual recording knows who it belongs to), your client language (the app starts in it), and where your chat frame is on screen (so the app can put its chat cover in the right spot). The app reads that file on your own PC. The addon sends nothing anywhere.
It never prints to your chat and it never turns logging off. If you turned it on yourself somewhere else, it stays on. The app works without the addon; the addon only takes /combatlog off your hands.