2 files changed, 82 insertions, 0 deletions
diff --git a/lua/clever_f/direct_preview_planner.lua b/lua/clever_f/direct_preview_planner.lua
new file mode 100644
index 0000000..7ead43f
--- /dev/null
+++ b/lua/clever_f/direct_preview_planner.lua
@@ -0,0 +1,64 @@
+local domain = require("clever_f.domain")
+local text_topology = require("clever_f.text_topology")
+
+local M = {}
+local DirectPreviewPlanner = {}
+DirectPreviewPlanner.__index = DirectPreviewPlanner
+M.DirectPreviewPlanner = DirectPreviewPlanner
+
+local planner_records = setmetatable({}, { __mode = "k" })
+
+local function fail(message, level)
+  error(message, (level or 1) + 1)
+end
+
+local function require_view(view)
+  if not text_topology.TextView.is(view) then
+    fail("direct preview text must be a TextView", 3)
+  end
+  return view
+end
+
+function DirectPreviewPlanner.new()
+  local planner = setmetatable({}, DirectPreviewPlanner)
+  planner_records[planner] = true
+  return planner
+end
+
+function DirectPreviewPlanner.is(value)
+  return type(value) == "table" and planner_records[value] == true
+end
+
+function DirectPreviewPlanner:scan_current_line(view, origin, direction)
+  require_view(view)
+  origin = domain.Position.coerce(origin)
+  direction = domain.Direction.from_string(direction)
+  local records = {}
+  for position, character, span in view:iterate(
+    direction,
+    view:line_match_start_bounds(origin.line)
+  ) do
+    records[#records + 1] = {
+      position = position,
+      character = character,
+      span = span,
+    }
+  end
+  return records
+end
+
+function M.new()
+  return DirectPreviewPlanner.new()
+end
+
+function M.scan_current_line(view, origin, direction)
+  return DirectPreviewPlanner.new():scan_current_line(view, origin, direction)
+end
+
+setmetatable(M, {
+  __call = function()
+    return DirectPreviewPlanner.new()
+  end,
+})
+
+return M
diff --git a/tests/run.lua b/tests/run.lua
index 7ca4e3c..e16f082 100644
--- a/tests/run.lua
+++ b/tests/run.lua
@@ -9,6 +9,7 @@ package.path = table.concat({
 local domain = require("clever_f.domain")
 local capabilities = require("clever_f.capabilities")
 local destination_engine = require("clever_f.destination_engine")
+local direct_preview_planner = require("clever_f.direct_preview_planner")
 local feedback_service = require("clever_f.feedback_service")
 local case_policy = require("clever_f.case_policy")
 local policy = require("clever_f.policy")
@@ -4540,6 +4541,23 @@ test("Cursor suppression requires policy and runtime support", function()
   same(1, operation_count(enabled, "suppress_cursor_presentation"))
 end)
 
+test("Direct preview scanning stays on the cursor line", function()
+  local view = text_topology.new({ "abc", "de", "fgh" }, "utf-8")
+  local planner = direct_preview_planner.new()
+  truthy(direct_preview_planner.DirectPreviewPlanner.is(planner))
+
+  local records = planner:scan_current_line(
+    view,
+    domain.Position.new(2, 2),
+    domain.Direction.FORWARD
+  )
+  same(2, #records)
+  same(domain.Position.new(2, 1), records[1].position)
+  same("d", records[1].character)
+  same(domain.Position.new(2, 2), records[2].position)
+  same("e", records[2].character)
+end)
+
 for _, item in ipairs(tests) do
   local ok, failure = xpcall(item.body, debug.traceback)
   if not ok then