Finish the wonderland: System told truthfully, in eight tabs instead of ten

Claude-Session: https://claude.ai/code/session_01Ms2FbjQy31TVf3CEvQhGM8

tests/quickshell/settings-backup-live-contract

@@ -173,6 +173,91 @@ status="$(qs_test ipc call settings-backup-behavior status)"
 jq -e '.calls == [] and (.lastError | contains("display change"))' <<<"$status" >/dev/null \
     || fail "display-busy restore refusal was not clean: $status"
 
+# ── The colour half of a display layout ─────────────────────────────────────
+#
+# Displays persists eleven fields per output. A restore read seven of them.
+#
+# The four it dropped -- VRR mode, colour profile, bit depth, SDR brightness
+# and saturation, plus the mirror source -- are the ones nobody notices going
+# missing, because the picture is still there and it is still the right size.
+# Worse, `layoutsEqual` compared the same seven, so a snapshot whose colour
+# settings differed from the live state compared EQUAL: the restore took the
+# early return, decided there was nothing to apply, and reported success while
+# leaving HDR off. A silent no-op that says it worked is the failure mode this
+# whole codebase keeps relearning, and this is it in the one place where the
+# evidence is a monitor looking slightly wrong.
+#
+# Both halves are asserted, because fixing either alone leaves the bug: reading
+# the fields without comparing them means the restore never runs; comparing
+# them without reading them means it runs and applies nothing.
+
+full='{
+  "DP-2":      {"mode":"4500x3000@60","scale":1.5,"transform":0,"x":-2560,"y":0,"primary":false,
+                "vrrMode":2,"colorProfile":"hdr","bitdepth":10,"sdrBrightness":1.2,
+                "sdrSaturation":0.9,"mirrorOf":""},
+  "HDMI-A-1":  {"mode":"2560x1440@60","scale":1,"transform":0,"x":0,"y":0,"primary":true,
+                "vrrMode":0,"colorProfile":"srgb","bitdepth":8,"sdrBrightness":1,
+                "sdrSaturation":1,"mirrorOf":"DP-2"}
+}'
+plain='{
+  "DP-2":      {"mode":"4500x3000@60","scale":1.5,"transform":0,"x":-2560,"y":0,"primary":false},
+  "HDMI-A-1":  {"mode":"2560x1440@60","scale":1,"transform":0,"x":0,"y":0,"primary":true}
+}'
+
+qs_test ipc call settings-backup-behavior reset >/dev/null
+
+restored="$(qs_test ipc call settings-backup-behavior layoutFor "$(jq -c . <<<"$full")")"
+jq -e '
+    (. != null) and (length == 2)
+    and (.[] | select(.name == "DP-2")
+         | .vrrMode == 2 and .colorProfile == "hdr" and .bitdepth == 10
+           and .sdrBrightness == 1.2 and .sdrSaturation == 0.9 and .mirrorOf == "")
+' <<<"$restored" >/dev/null \
+    || fail "a stored layout's colour fields did not survive the trip back into a live layout: $restored"
+jq -e '.[] | select(.name == "HDMI-A-1") | .mirrorOf == "DP-2" and .bitdepth == 8' \
+    <<<"$restored" >/dev/null \
+    || fail "the mirror source did not survive the trip back into a live layout: $restored"
+
+# Back-compat, in the same shape Displays.isPersistedLayoutEntry uses: a record
+# written before these fields existed is still a record. Refusing it would turn
+# every snapshot anybody already has into one that cannot be restored.
+legacy="$(qs_test ipc call settings-backup-behavior layoutFor "$(jq -c . <<<"$plain")")"
+jq -e '(. != null) and (length == 2) and (.[] | select(.name == "DP-2") | .scale == 1.5)' \
+    <<<"$legacy" >/dev/null \
+    || fail "a stored layout without the colour fields was refused, so older snapshots cannot be restored: $legacy"
+
+# And the comparison. Two layouts identical but for a colour profile are not
+# equal -- this is the assertion the shipped behaviour FAILS, and the reason
+# the restore silently did nothing.
+# The two layouts travel as one object: the IPC client turns a top-level JSON
+# array into one argument per element, so passing two layouts as two arguments
+# arrives as four.
+compare() {
+    qs_test ipc call settings-backup-behavior layoutsMatch \
+        "$(jq -c -n --argjson left "$1" --argjson right "$2" '{left: $left, right: $right}')"
+}
+
+drifted="$(jq -c '.[0].colorProfile = "srgb"' <<<"$restored")"
+[[ "$(compare "$restored" "$drifted")" == "false" ]] \
+    || fail 'layoutsEqual calls two layouts equal when their colour profiles differ, so a restore that should change the picture takes the early return and reports success'
+for field in vrrMode bitdepth sdrBrightness sdrSaturation mirrorOf; do
+    case "$field" in
+        mirrorOf) drifted="$(jq -c --arg f "$field" '.[0][$f] = "HDMI-A-1"' <<<"$restored")" ;;
+        *)        drifted="$(jq -c --arg f "$field" '.[0][$f] = 7' <<<"$restored")" ;;
+    esac
+    [[ "$(compare "$restored" "$drifted")" == "false" ]] \
+        || fail "layoutsEqual ignores $field, so a snapshot differing only in it restores nothing"
+done
+[[ "$(compare "$restored" "$restored")" == "true" ]] \
+    || fail 'layoutsEqual no longer calls a layout equal to itself, which would make every restore reapply the geometry it already has'
+
+# The tolerance on the two float fields is a tolerance, not an exemption: a
+# value that came back one ulp different is the same value, a value somebody
+# changed is not.
+nudged="$(jq -c '.[0].sdrBrightness = 1.2000001' <<<"$restored")"
+[[ "$(compare "$restored" "$nudged")" == "true" ]] \
+    || fail 'a float that came back with a rounding difference is treated as a change, so every restore would reapply the layout it already has'
+
 trap - EXIT
 cleanup
 printf 'settings backup live contract: PASS\n'