Two things the security doc left implicit, both measured on 2026-07-31.
The `_drm` authorization is described as per-connection, which undersells it.
DRM/KMS capture is not session-scoped - it grabs the physical scanout of a CRTC
no matter which session owns the display - so the check is re-run on every
frame, and when a user logs in at a greeter the greeter's stream is closed
rather than continued. That is the property that stops an outgoing greeter
process from capturing the screen of the user who just logged in, and it is
worth stating where a reader is looking for exactly that confinement.
And the wake section never said what happens after the wake. It resets the
compositor's idle timer; it does not hold the display on. Left alone, the
connector idles off again one full idle period later: 30.3 s at a GDM greeter,
70.3 s in a user session with idle-delay=60. Saying so makes the existing
"useless as a way to keep a screen lit" clause concrete, and points at the
component whose job that actually is.
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