Redaction

LUCI has two ways to keep something out of your memory, and they solve different problems. One removes an app from the capture. The other removes a secret from a frame you did want to capture.

Both live in Local Settings → Privacy.

Never record an app

Add an app to the privacy list and its windows stop appearing in captures.

On Windows this happens at the compositor level: the app's pixels are never drawn into the frame LUCI receives, so there is no moment where an unmasked copy exists. On macOS, LUCI paints opaque black over every window that app owns before the frame is stored.

If you are actually working in a privacy app — it is the front window — LUCI skips the whole frame rather than saving a screenshot that is mostly a black rectangle.

You add apps by picking from a list of what is running, with icons, rather than typing executable names. Changes take effect on the very next captured frame; there is nothing to restart.

Redact sensitive info

The privacy list is per-app. Redaction is per-frame, and it catches things that show up anywhere.

Redaction is off until you switch it on. Turn on Redact sensitive info and every captured frame is read before the image is written to disk. Anything matching a sensitive pattern gets an opaque black rectangle painted over it, and the matched text is stripped out of what goes to the search index — so the secret is in neither the screenshot nor the searchable text.

You choose which categories are matched. All four are on when you enable it:

Unticking a category takes effect on the next frame.

How detection works, and what it misses

Detection is pattern matching plus checksums — no model, no guessing. That is a deliberate trade: it is fast enough to run on every frame, it behaves identically whatever language your screen is in, and it almost never blacks out something innocent. A false positive here means a rectangle over content you needed.

The cost of that choice is the things it does not catch:

• Free-form personal information. Names, addresses, and anything else that only a human or a model could recognize as sensitive.
• Phone numbers. Deliberately left out — they are indistinguishable from timestamps and order numbers often enough that including them would black out the wrong things.
• Passwords in plain fields. A password has no shape to match. Use the privacy app list for anything that shows credentials, and let your password manager keep them masked.

There is also a platform difference in how tightly the rectangle fits. On Windows LUCI has word-level positions, so it blacks out just the matched words. On macOS, Apple's text recognition reports whole lines, so the entire line containing the match is blacked out. Neither leaks; the Mac one is simply coarser.

Related

• Privacy on device for where the data lives and what leaves
• What gets captured for what a frame contains
• Screen recording for turning capture on and off