Tag three requirements the code already meets

R5 says in its own note that zoom_resolution.rs establishes it as a
pixel equality; that file was tagged FR-DSP-5 alone. FR-DEV-19's three
sub-clauses carry eighty-three tags between them while the parent had
none; MaskLayer, which is the thing they edit, now carries it. And
NFR-R3 — a crash in decode does not take down the application, the
image is marked failed — is exactly what the decoder's panic guard and
the face sweep's unreadable mark do, tagged FR-RAW-4 and NFR-SEC-1 and
not the clause that asked for them.

core/dr-gpu/tests/zoom_resolution.rs

@@ -1,4 +1,4 @@
-//! TRACES: FR-DSP-5
+//! TRACES: FR-DSP-5 | R5
 //! Zooming to 1:1 samples the source, pixel for pixel.
 //!
 //! FR-DSP-5: *"Fit, 1:1, and arbitrary zoom levels. At 1:1 and above, the