feat(tui): use DA1 response to determine OSC 52 support

Many terminals now include support for OSC 52 in their Primary Device
Attributes (DA1) response. This is preferable to using XTGETTCAP because
DA1 is _much_ more broadly supported.

runtime/plugin/osc52.lua

@@ -19,33 +19,77 @@ vim.api.nvim_create_autocmd('UIEnter', {
       end
     end
 
-    -- Do not query when any of the following is true:
-    --   * No TUI is attached
-    --   * Using a badly behaved terminal
-    if not tty or vim.env.TERM_PROGRAM == 'Apple_Terminal' then
-      local termfeatures = vim.g.termfeatures or {} ---@type TermFeatures
-      termfeatures.osc52 = nil
-      vim.g.termfeatures = termfeatures
+    -- Do not query when no TUI is attached
+    if not tty then
       return
     end
 
-    require('vim.termcap').query('Ms', function(cap, found, seq)
-      if not found then
-        return
-      end
-
-      assert(cap == 'Ms')
-
-      -- If the terminal reports a sequence other than OSC 52 for the Ms capability
-      -- then ignore it. We only support OSC 52 (for now)
-      if not seq or not seq:match('^\027%]52') then
-        return
-      end
-
+    -- Clear existing OSC 52 value, since this is a new UI we might be attached to a different
+    -- terminal
+    do
       local termfeatures = vim.g.termfeatures or {} ---@type TermFeatures
-      termfeatures.osc52 = true
+      termfeatures.osc52 = nil
       vim.g.termfeatures = termfeatures
-    end)
+    end
+
+    -- Check DA1 first
+    vim.api.nvim_create_autocmd('TermResponse', {
+      group = id,
+      nested = true,
+      callback = function(args)
+        local resp = args.data.sequence ---@type string
+        local params = resp:match('^\027%[%?([%d;]+)c$')
+        if params then
+          -- Check termfeatures again, it may have changed between the query and response.
+          if vim.g.termfeatures ~= nil and vim.g.termfeatures.osc52 ~= nil then
+            return true
+          end
+
+          for param in string.gmatch(params, '%d+') do
+            if param == '52' then
+              local termfeatures = vim.g.termfeatures or {} ---@type TermFeatures
+              termfeatures.osc52 = true
+              vim.g.termfeatures = termfeatures
+              return true
+            end
+          end
+
+          -- Do not use XTGETTCAP on terminals that echo unknown sequences
+          if vim.env.TERM_PROGRAM == 'Apple_Terminal' then
+            return true
+          end
+
+          -- Fallback to XTGETTCAP
+          require('vim.termcap').query('Ms', function(cap, found, seq)
+            if not found then
+              return
+            end
+
+            -- Check termfeatures again, it may have changed between the query and response.
+            if vim.g.termfeatures ~= nil and vim.g.termfeatures.osc52 ~= nil then
+              return
+            end
+
+            assert(cap == 'Ms')
+
+            -- If the terminal reports a sequence other than OSC 52 for the Ms capability
+            -- then ignore it. We only support OSC 52 (for now)
+            if not seq or not seq:match('^\027%]52') then
+              return
+            end
+
+            local termfeatures = vim.g.termfeatures or {} ---@type TermFeatures
+            termfeatures.osc52 = true
+            vim.g.termfeatures = termfeatures
+          end)
+
+          return true
+        end
+      end,
+    })
+
+    -- Write DA1 request
+    io.stdout:write('\027[c')
   end,
 })