diff --git a/lua/forester.lua b/lua/forester.lua
index 63c3aff..b45310f 100644
--- a/lua/forester.lua
+++ b/lua/forester.lua
@@ -1,4 +1,5 @@
 local api = vim.api
+local CompletionSource = require("forester.completion")
 local Commands = require("forester.commands")
 local Forester = require("forester.bindings")
 local util = require("forester.util")
@@ -32,6 +33,10 @@ local function setup(config)
   if not config then
     config = { opts = { tree_dirs = "trees" } }
   end
+
+  ---Register your source to nvim-cmp.
+  require("cmp").register_source("month", CompletionSource)
+
   local opts = config.opts
   ensure_treesitter()
   vim.opt.path:append("trees")
diff --git a/lua/forester/completion.lua b/lua/forester/completion.lua
new file mode 100644
index 0000000..fb86f10
--- /dev/null
+++ b/lua/forester/completion.lua
@@ -0,0 +1,70 @@
+local source = {}
+
+---Return whether this source is available in the current context or not (optional).
+---@return boolean
+function source:is_available()
+  return true
+end
+
+---Return the debug name of this source (optional).
+---@return string
+function source:get_debug_name()
+  return "forester cmp"
+end
+
+---Return LSP's PositionEncodingKind.
+---@NOTE: If this method is omitted, the default value will be `utf-16`.
+---@return lsp.PositionEncodingKind
+function source:get_position_encoding_kind()
+  return "utf-16"
+end
+
+---Return the keyword pattern for triggering completion (optional).
+---If this is omitted, nvim-cmp will use a default keyword pattern. See |cmp-config.completion.keyword_pattern|.
+---@return string
+function source:get_keyword_pattern()
+  return [[\k\+]]
+end
+
+---Return trigger characters for triggering completion (optional).
+function source:get_trigger_characters()
+  return { "\\" }
+end
+
+---Invoke completion (required).
+---@param params cmp.SourceCompletionApiParams
+---@param callback fun(response: lsp.CompletionResponse|nil)
+function source:complete(params, callback)
+  callback({
+    { label = "title" },
+    { label = "author" },
+    { label = "date" },
+    { label = "taxon" },
+    { label = "def" },
+    { label = "import" },
+    { label = "export" },
+    { label = "p" },
+    { label = "strong" },
+    { label = "transclude" },
+    { label = "let" },
+    { label = "code" },
+    { label = "tex" },
+  })
+end
+
+---Resolve completion item (optional). This is called right before the completion is about to be displayed.
+---Useful for setting the text shown in the documentation window (`completion_item.documentation`).
+---@param completion_item lsp.CompletionItem
+---@param callback fun(completion_item: lsp.CompletionItem|nil)
+function source:resolve(completion_item, callback)
+  callback(completion_item)
+end
+
+---Executed after the item was selected.
+---@param completion_item lsp.CompletionItem
+---@param callback fun(completion_item: lsp.CompletionItem|nil)
+function source:execute(completion_item, callback)
+  callback(completion_item)
+end
+
+return source
diff --git a/lua/forester/lsp.lua b/lua/forester/lsp.lua
new file mode 100644
index 0000000..e69de29
diff --git a/lua/forester/ui.lua b/lua/forester/ui.lua
index 129bfaf..583e6e2 100644
--- a/lua/forester/ui.lua
+++ b/lua/forester/ui.lua
@@ -5,7 +5,7 @@ local M = {}
 local draw_title_inlay = function(bufnr, pos, title)
   local r = pos[1]
   local c = pos[2]
-  --api.nvim_buf_set_extmark(bufnr, forester_ns, r, c, { virt_text = { { title, "@comment" } }, virt_text_pos = "eol" })
+  api.nvim_buf_set_extmark(bufnr, forester_ns, r, c, { virt_text = { { title, "@comment" } }, virt_text_pos = "eol" })
 end
 
 local draw_inline_hints = function(bufnr)
@@ -40,6 +40,8 @@ local draw_inline_hints = function(bufnr)
   end
 end
 
+draw_inline_hints(0)
+
 M.draw_title_inlay = draw_title_inlay
 M.draw_inline_hints = draw_inline_hints