perf: async cache initialization and remove deepcopy

Problem: first completion request blocked the UI with a synchronous
vim.system():wait() call, and every subsequent key completion
unnecessarily deep-copied the entire cache.

Solution: use vim.system with an async callback to initialize the cache
without blocking. Queue pending completion requests during loading and
serve them once parsing finishes. Return cached keys directly instead
of deep-copying.

lua/blink-cmp-ghostty.lua

@@ -5,6 +5,9 @@ local M = {}
 local keys_cache = nil
 ---@type table<string, string[]>?
 local enums_cache = nil
+local loading = false
+---@type {ctx: blink.cmp.Context, callback: fun(response: blink.cmp.CompletionResponse)}[]
+local pending = {}
 
 function M.new()
   return setmetatable({}, { __index = M })
@@ -15,14 +18,14 @@ function M.enabled()
   return vim.bo.filetype == 'ghostty'
 end
 
+---@param stdout string
 ---@return blink.cmp.CompletionItem[]
-local function parse_keys()
+local function parse_keys(stdout)
   local Kind = require('blink.cmp.types').CompletionItemKind
-  local result = vim.system({ 'ghostty', '+show-config', '--docs' }):wait()
   local items = {}
   local doc_lines = {}
 
-  for line in ((result.stdout or '') .. '\n'):gmatch('(.-)\n') do
+  for line in (stdout .. '\n'):gmatch('(.-)\n') do
     if line:match('^#') then
       local stripped = line:gsub('^# ?', '')
       doc_lines[#doc_lines + 1] = stripped
@@ -79,13 +82,7 @@ end
 
 ---@param ctx blink.cmp.Context
 ---@param callback fun(response: blink.cmp.CompletionResponse)
----@return fun()
-function M:get_completions(ctx, callback)
-  if not keys_cache then
-    keys_cache = parse_keys()
-    enums_cache = parse_enums()
-  end
-
+local function respond(ctx, callback)
   local line = ctx.line
   local col = ctx.cursor[2]
   local eq_pos = line:find('=')
@@ -108,16 +105,42 @@ function M:get_completions(ctx, callback)
         is_incomplete_backward = false,
         items = items,
       })
-      return function() end
+      return
     end
     callback({ items = {} })
   else
     callback({
       is_incomplete_forward = false,
       is_incomplete_backward = false,
-      items = vim.deepcopy(keys_cache),
+      items = keys_cache,
     })
   end
+end
+
+---@param ctx blink.cmp.Context
+---@param callback fun(response: blink.cmp.CompletionResponse)
+---@return fun()
+function M:get_completions(ctx, callback)
+  if keys_cache then
+    respond(ctx, callback)
+    return function() end
+  end
+
+  pending[#pending + 1] = { ctx = ctx, callback = callback }
+  if not loading then
+    loading = true
+    vim.system({ 'ghostty', '+show-config', '--docs' }, {}, function(result)
+      vim.schedule(function()
+        keys_cache = parse_keys(result.stdout or '')
+        enums_cache = parse_enums()
+        loading = false
+        for _, p in ipairs(pending) do
+          respond(p.ctx, p.callback)
+        end
+        pending = {}
+      end)
+    end)
+  end
   return function() end
 end
 

spec/ghostty_spec.lua

@@ -19,24 +19,31 @@ local BASH_COMPLETION = table.concat({
 }, '\n')
 
 local function mock_system()
-  local original = vim.system
+  local original_system = vim.system
+  local original_schedule = vim.schedule
   ---@diagnostic disable-next-line: duplicate-set-field
-  vim.system = function(cmd)
+  vim.system = function(cmd, _, on_exit)
     if cmd[1] == 'ghostty' then
-      return {
-        wait = function()
-          return { stdout = CONFIG_DOCS, code = 0 }
-        end,
-      }
+      local result = { stdout = CONFIG_DOCS, code = 0 }
+      if on_exit then
+        on_exit(result)
+        return {}
+      end
+      return { wait = function() return result end }
     end
-    return {
-      wait = function()
-        return { stdout = '', code = 1 }
-      end,
-    }
+    local result = { stdout = '', code = 1 }
+    if on_exit then
+      on_exit(result)
+      return {}
+    end
+    return { wait = function() return result end }
+  end
+  vim.schedule = function(fn)
+    fn()
   end
   return function()
-    vim.system = original
+    vim.system = original_system
+    vim.schedule = original_schedule
   end
 end