diff --git a/lua/u/buffer.lua b/lua/u/buffer.lua
index 410d1d3..0305349 100644
--- a/lua/u/buffer.lua
+++ b/lua/u/buffer.lua
@@ -75,6 +75,9 @@ function Buffer:autocmd(event, opts)
   vim.api.nvim_create_autocmd(event, vim.tbl_extend('force', opts, { buffer = self.bufnr }))
 end
 
+--- @param fn function
+function Buffer:call(fn) return vim.api.nvim_buf_call(self.bufnr, fn) end
+
 --- @param tree u.renderer.Tree
 function Buffer:render(tree) return self.renderer:render(tree) end
 
diff --git a/lua/u/renderer.lua b/lua/u/renderer.lua
index 0a98d61..2a1d353 100644
--- a/lua/u/renderer.lua
+++ b/lua/u/renderer.lua
@@ -157,7 +157,7 @@ function Renderer.markup_to_string(opts) return table.concat(Renderer.markup_to_
 --- @param bufnr number
 --- @param old_lines string[] | nil
 --- @param new_lines string[]
-function Renderer.patch_lines(bufnr, old_lines, new_lines)
+function Renderer.patch_lines(bufnr, old_lines, new_lines) -- {{{
   --
   -- Helpers:
   --
@@ -210,7 +210,7 @@ function Renderer.patch_lines(bufnr, old_lines, new_lines)
       -- No change
     end
   end
-end
+end -- }}}
 
 --- @param tree u.renderer.Tree
 function Renderer:render(tree) -- {{{
@@ -274,25 +274,6 @@ function Renderer:render(tree) -- {{{
   self:_reconcile()
 end -- }}}
 
---- @private
---- @param start integer
---- @param end_ integer
---- @param strict_indexing boolean
---- @param replacement string[]
-function Renderer:_set_lines(start, end_, strict_indexing, replacement)
-  vim.api.nvim_buf_set_lines(self.bufnr, start, end_, strict_indexing, replacement)
-end
-
---- @private
---- @param start_row integer
---- @param start_col integer
---- @param end_row integer
---- @param end_col integer
---- @param replacement string[]
-function Renderer:_set_text(start_row, start_col, end_row, end_col, replacement)
-  vim.api.nvim_buf_set_text(self.bufnr, start_row, start_col, end_row, end_col, replacement)
-end
-
 --- @private
 function Renderer:_reconcile() -- {{{
   --
@@ -372,7 +353,7 @@ function Renderer:_expr_map_callback(mode, lhs) -- {{{
   return cancel and '' or lhs
 end -- }}}
 
-function Renderer:_on_text_changed()
+function Renderer:_on_text_changed() -- {{{
   -- Reset changedtick, so that the reconciler knows to refresh its cached
   -- buffer-content before computing the diff:
   self.changedtick = 0
@@ -428,9 +409,10 @@ function Renderer:_on_text_changed()
       end
     end
   end
-end
+end -- }}}
 
-function Renderer:_debug()
+--- @private
+function Renderer:_debug() -- {{{
   local prev_w = vim.api.nvim_get_current_win()
   vim.cmd.vnew()
   local info_bufnr = vim.api.nvim_get_current_buf()
@@ -450,6 +432,8 @@ function Renderer:_debug()
     ids,
     vim.api.nvim_create_autocmd({ 'CursorMoved', 'CursorMovedI' }, {
       callback = function()
+        if vim.api.nvim_get_current_win() ~= prev_w then return end
+
         local l, c = unpack(vim.api.nvim_win_get_cursor(0))
         l = l - 1 -- make it actually 0-based
 
@@ -489,7 +473,7 @@ function Renderer:_debug()
   )
 
   vim.api.nvim_set_current_win(prev_w)
-end
+end -- }}}
 
 --- Returns pairs of extmarks and tags associate with said extmarks. The
 --- returned tags/extmarks are sorted smallest (innermost) to largest
@@ -610,6 +594,19 @@ function Renderer:get_tags_at(pos0, mode) -- {{{
 
   return matching_tags
 end -- }}}
+
+--- @private
+--- @param tag_or_id string | u.renderer.Tag
+--- @return { start: [number, number]; stop: [number, number] } | nil
+function Renderer:get_tag_bounds(tag_or_id) -- {{{
+  for _, x in ipairs(self.curr.extmarks) do
+    local pos = { start = x.start, stop = x.stop }
+    local does_tag_match = type(tag_or_id) == 'string' and x.tag.attributes.id == tag_or_id
+      or x.tag == tag_or_id
+    if does_tag_match then return pos end
+  end
+end -- }}}
+
 -- }}}
 
 -- TreeBuilder {{{
diff --git a/spec/renderer_spec.lua b/spec/renderer_spec.lua
index 60036db..a4d5833 100644
--- a/spec/renderer_spec.lua
+++ b/spec/renderer_spec.lua
@@ -203,4 +203,60 @@ describe('Renderer', function()
       assert.are.same(captured_changed_text, 'bleh')
     end)
   end)
+
+  it('should find tags by position', function()
+    withbuf({}, function()
+      local r = R.Renderer.new(0)
+      r:render {
+        'pre',
+        R.h('text', {
+          id = 'outer',
+        }, {
+          'inner-pre',
+          R.h('text', {
+            id = 'inner',
+          }, {
+            'inner-text',
+          }),
+          'inner-post',
+        }),
+        'post',
+      }
+
+      local tags = r:get_tags_at { 0, 11 }
+      assert.are.same(#tags, 1)
+      assert.are.same(tags[1].tag.attributes.id, 'outer')
+
+      tags = r:get_tags_at { 0, 12 }
+      assert.are.same(#tags, 2)
+      assert.are.same(tags[1].tag.attributes.id, 'inner')
+      assert.are.same(tags[2].tag.attributes.id, 'outer')
+    end)
+  end)
+
+  it('should find tags by id', function()
+    withbuf({}, function()
+      local r = R.Renderer.new(0)
+      r:render {
+        R.h('text', {
+          id = 'outer',
+        }, {
+          'inner-pre',
+          R.h('text', {
+            id = 'inner',
+          }, {
+            'inner-text',
+          }),
+          'inner-post',
+        }),
+        'post',
+      }
+
+      local bounds = r:get_tag_bounds 'outer'
+      assert.are.same(bounds, { start = { 0, 0 }, stop = { 0, 29 } })
+
+      bounds = r:get_tag_bounds 'inner'
+      assert.are.same(bounds, { start = { 0, 9 }, stop = { 0, 19 } })
+    end)
+  end)
 end)