fix(api): clamp range lines in nvim__redraw() (#31710)

Problem:
`nvim__redraw()` doesn't clamp the lines in the `range` parameter before truncating to int. The resulting range may be empty when the original range contained buffer lines and vice versa.

E.g. for a buffer with 4 lines, these are the redrawn lines:

```lua
{ 2, 2 ^ 31 } -> none (should be { 2, 3 })
{ 2, 2 ^ 32 } -> none (should be { 2, 3 })
{ 2 ^ 32 - 1, 2 } -> { 0, 1 } (should be none)
```

Solution:
Clamp `range` values before truncating to int.

src/nvim/api/vim.c

@@ -2374,13 +2374,23 @@ void nvim__redraw(Dict(redraw) *opts, Error *err)
              "%s", "Invalid 'range': Expected 2-tuple of Integers", {
       return;
     });
-    linenr_T first = (linenr_T)kv_A(opts->range, 0).data.integer + 1;
+    int64_t begin_raw = kv_A(opts->range, 0).data.integer;
-    linenr_T last = (linenr_T)kv_A(opts->range, 1).data.integer;
+    int64_t end_raw = kv_A(opts->range, 1).data.integer;
+
     buf_T *rbuf = win ? win->w_buffer : (buf ? buf : curbuf);
-    if (last == -1) {
+    linenr_T line_count = rbuf->b_ml.ml_line_count;
-      last = rbuf->b_ml.ml_line_count;
+
+    int begin = (int)MIN(begin_raw, line_count);
+    int end;
+    if (end_raw == -1) {
+      end = line_count;
+    } else {
+      end = (int)MIN(MAX(begin, end_raw), line_count);
+    }
+
+    if (begin < end) {
+      redraw_buf_range_later(rbuf, 1 + begin, end);
     }
-    redraw_buf_range_later(rbuf, first, last);
   }
 
   // Redraw later types require update_screen() so call implicitly unless set to false.

test/functional/api/vim_spec.lua

@@ -5385,8 +5385,53 @@ describe('API', function()
         13                                                          |
       ]],
     })
-    -- takes buffer line count from correct buffer with "win" and {0, -1} "range"
+  end)
-    api.nvim__redraw({ win = 0, range = { 0, -1 } })
+
+  it('nvim__redraw range parameter', function()
+    Screen.new(10, 5)
+    fn.setline(1, fn.range(4))
+
+    exec_lua([[
+      _G.lines_list = {}
+      ns = vim.api.nvim_create_namespace('')
+      vim.api.nvim_set_decoration_provider(ns, {
+        on_win = function()
+        end,
+        on_line = function(_, _, _, line)
+          table.insert(_G.lines_list, line)
+        end,
+      })
+      function _G.get_lines()
+        local lines = _G.lines_list
+        _G.lines_list = {}
+        return lines
+      end
+    ]])
+
+    api.nvim__redraw({ flush = true, valid = false })
+    exec_lua('_G.get_lines()')
+
+    local actual_lines = {}
+    local function test(range)
+      api.nvim__redraw({ win = 0, range = range })
+      table.insert(actual_lines, exec_lua('return _G.get_lines()'))
+    end
+
+    test({ 0, -1 })
+    test({ 2, 2 ^ 31 })
+    test({ 2, 2 ^ 32 })
+    test({ 2 ^ 31 - 1, 2 })
+    test({ 2 ^ 32 - 1, 2 })
+
+    local expected_lines = {
+      { 0, 1, 2, 3 },
+      { 2, 3 },
+      { 2, 3 },
+      {},
+      {},
+    }
+    eq(expected_lines, actual_lines)
+
     n.assert_alive()
   end)
 end)