fix(files): handle stale treesitter nodes gracefully

lua/orgmode/files/file.lua

@@ -34,10 +34,18 @@ local clean_empty_line = vim.fn.has('nvim-0.13') == 1 or vim.fn.has('nvim-0.12.3
 ---@field root TSNode
 local OrgFile = {}
 
+-- The root node id only changes on a re-parse, so a buffer edited since the
+-- last parse would still hit results built for the old tree. The changedtick
+-- in the key turns that into a miss, and the method re-parses when it runs.
 local memoize = Memoize:new(OrgFile, function(self)
+  local tick = 0
+  local bufnr = self:bufnr()
+  if bufnr > -1 then
+    tick = vim.api.nvim_buf_get_changedtick(bufnr)
+  end
   return {
     file = self,
-    id = table.concat({ 'file', self.root and self.root:id() or '' }, '_'),
+    id = table.concat({ 'file', self.root and self.root:id() or '', tick }, '_'),
   }
 end)
 

tests/plenary/files/file_spec.lua

@@ -459,6 +459,36 @@ describe('OrgFile', function()
     end)
   end)
 
+  describe('memoized methods', function()
+    it('should reparse a buffer edited since the last parse', function()
+      local filename = vim.fn.tempname() .. '.org'
+      local file = load_file_sync({
+        '* First',
+        '* Second',
+        ':PROPERTIES:',
+        ':ID: second-id',
+        ':END:',
+        'body',
+        'body',
+        'body',
+      }, filename)
+      vim.cmd('edit ' .. filename)
+      file:reload_sync()
+
+      local headlines = file:get_headlines_including_archived()
+      assert.are.same(2, #headlines)
+      assert.are.same('second-id', headlines[2]:get_property('ID'))
+
+      -- Unsaved edit shrinks the buffer, no reload in between
+      vim.api.nvim_buf_set_lines(0, 1, -1, false, {})
+
+      headlines = file:get_headlines_including_archived()
+      assert.are.same(1, #headlines)
+      assert.are.same('First', headlines[1]:get_title())
+      vim.cmd('bwipeout!')
+    end)
+  end)
+
   describe('get_node_text_list', function()
     local file = load_file_sync({
       '* Headline 1 :TAG:',