From b298bab1bf4dc5fdd07de867ad922f0157abbaee Mon Sep 17 00:00:00 2001
From: Jackson Moore <jacksonmoore@tuta.io>
Date: Fri, 4 Sep 2026 11:41:31 +0200
Subject: Scan uppercase previews backward

---
 lua/clever_f/direct_preview_planner.lua | 14 +++++++++++---
 tests/run.lua                           | 19 +++++++++++++++++++
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/lua/clever_f/direct_preview_planner.lua b/lua/clever_f/direct_preview_planner.lua
index 85dfcbc..8ccfa75 100644
--- a/lua/clever_f/direct_preview_planner.lua
+++ b/lua/clever_f/direct_preview_planner.lua
@@ -48,12 +48,20 @@ function DirectPreviewPlanner:scan_current_line(view, origin, direction)
   return records
 end
 
-function DirectPreviewPlanner:scan_for_descriptor(view, origin, descriptor)
+function M.direction_for_descriptor(descriptor)
   descriptor = domain.Descriptor.from_string(descriptor)
   if domain.Descriptor.is_uppercase(descriptor) then
-    fail("backward direct preview scanning is not available", 2)
+    return domain.Direction.BACKWARD
   end
-  return self:scan_current_line(view, origin, domain.Direction.FORWARD)
+  return domain.Direction.FORWARD
+end
+
+function DirectPreviewPlanner:scan_for_descriptor(view, origin, descriptor)
+  return self:scan_current_line(
+    view,
+    origin,
+    M.direction_for_descriptor(descriptor)
+  )
 end
 
 function M.new()
diff --git a/tests/run.lua b/tests/run.lua
index 7e47330..cbca8d9 100644
--- a/tests/run.lua
+++ b/tests/run.lua
@@ -4595,6 +4595,25 @@ test("Lower-case descriptors scan direct previews forward", function()
   end
 end)
 
+test("Upper-case descriptors scan direct previews backward", function()
+  local view = text_topology.new({ "abcde" }, "utf-8")
+  local planner = direct_preview_planner.new()
+  local origin = domain.Position.new(1, 5)
+
+  for _, descriptor in ipairs({ "F", "T" }) do
+    local records = planner:scan_for_descriptor(view, origin, descriptor)
+    same(4, #records)
+    same("d", records[1].character)
+    same(domain.Position.new(1, 4), records[1].position)
+    same("a", records[4].character)
+    same(domain.Position.new(1, 1), records[4].position)
+  end
+  same(
+    domain.Direction.BACKWARD,
+    direct_preview_planner.direction_for_descriptor("F")
+  )
+end)
+
 for _, item in ipairs(tests) do
   local ok, failure = xpcall(item.body, debug.traceback)
   if not ok then
-- 
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