Customizing a RegionPlot

I would like to customize the RegionPlot with the following:

1. Add text ticks to the RegionPlot
2. Change 1 to show as a or another text
3. Add a vertical Red line at such a tick location

Code:

RegionPlot[{x^2 + y^2 < 2}, {x, 0, 1.5}, {y, -1.5, 1.5},
FrameTicks -> {{None, None}, {{1}, None}}]


Expected Outcome:

• RegionPlot[{x^2 + y^2 < 2} , {x, 0, 1.5}, {y, -1.5, 1.5} , FrameTicks -> {{None, None}, {{{1, Style["a", 16, Red]}}, None}} , Frame -> True , Epilog -> { Red, AbsoluteThickness[2] , InfiniteLine[{{1, 0}, {1, 1}}] } ]
– Syed
Nov 18, 2022 at 7:56

• The parametric of the Ticks is {{x, label, {plen, mlen}, style}}.

• we extend the tick to full size by using  {plen, mlen}={1., 0.}, that is, the positive directions is 1. and the negative directions is 0.

RegionPlot[{x^2 + y^2 < 2}, {x, 0, 1.5}, {y, -1.5, 1.5},
FrameTicks -> {{None,
None}, {{{1, Style["a", Blue, 14], {1., 0.},
Directive[Red, Thick]}}, None}}]


Something like:

RegionPlot[{x^2 + y^2 < 2}, {x, 0, 1.5}, {y, -1.5, 1.5},
FrameTicks -> {{{{-1, "mone"}, {-0.5, "mhalf"}, {0, "zero"}, {0.5,
"half"}, {1, "one"}},
None}, {{{0, "zero"}, {0.5, "half"}, {1, "one", {1, 0},
Directive[Red, Thick]}, {1.5, "onehalf"}}, None}}]