Sweated or compression angle stop?

[Venkman]

Is this angle stop on my toilet supply line a sweated or a compression fitting?
Edit: I included a 3rd photo that might answer the question. It appears the valve is permanently affixed to a silvered nipple that is soldered to the copper stub, behind the escutcheon. Best of all worlds, LOL. That nipple must be larger in diameter than the 1/2" copper stub since it appears to fit over it. Valve is 30 years old and is letting water seep through, even when completely closed. Is it possible to rebuild or should it just be replaced?

[TinyTool]

From what I've found, this setup seems closer to a sweat-on valve rather than a compression one. The inlet side doesn't have the separate compression nut and ferrule that normally show up on compression stops. Instead, it looks like a smooth sleeve that was soldered onto the copper stub, which matches the older sweat-on style valves.

Given that it's around 30 years old and no longer shutting off fully, it's usually better to replace rather than rebuild. The internal parts tend to wear out, and even new washers may not seal well against a worn seat.

For replacement, a plumber can remove the old sweated connection, or, if the copper stub is long enough, a compression or push-to-connect valve can be used instead.

Hope this points you in the right direction!

[Venkman]

Yes, that is helpful. Thank you.

[TinyTool]

You're welcome!

[qinghailu]

It has been in use for too long; replacement is recommended.
ZXLSEAL toilet seal

[AshRae]

Based on your edit, you've already figured it out — that's a solder/sweat connection on the stub-out, with the valve body permanently attached. What you're seeing at the top is a compression nut where the supply line connects, but the valve itself isn't going anywhere without a torch.

On the rebuild vs. replace question: at 30 years old, just replace it. Rebuild kits exist for some angle stops, but the seats and stems on valves that age are usually worn or corroded enough that a new washer buys you maybe another year or two before you're back under there. A new quarter-turn ball valve angle stop runs $8–15 at any home center and will outlast the house.

The process isn't bad at all — shut off the main, drain the line, cut the copper stub just below the old valve, and sweat on a new one. If you're not comfortable with a torch, a push-fit (SharkBite style) angle stop is a legitimate option for a supply line stub — not everyone's favorite, but perfectly acceptable in a low-movement, accessible location like behind a toilet.

Given that it's already seeping with the valve fully closed, I wouldn't wait on this one. A valve that won't fully close is one forgotten moment away from a real mess.