fix: shallow copy in store.mutate via vim.tbl_extend

[Copilot]

M.mutate was using vim.deepcopy to snapshot state before mutation, which causes problems with certain table structures (issue #331).

Change

Replace deep copy with a shallow copy using vim.tbl_extend:

-- before
local old = vim.deepcopy(current)

-- after
local old = vim.tbl_extend('force', {}, current)

Original prompt

In lua/opencode/state/store.lua, there is an issue with vim.deepcopy in the M.mutate function which causes problems (resolves issue #331).

Please replace the vim.deepcopy call in M.mutate with a shallow copy using vim.tbl_extend.

Specifically, change this line:

local old = vim.deepcopy(current)

To:

local old = vim.tbl_extend('force', {}, current)

The following is the prior conversation context from the user's chat exploration (may be truncated):

User: #331

There is an issue with deepcopy in mutate in store.lua. can you replace it with a shallow copy .

Assistant: I found the mutate function in lua/opencode/state/store.lua. Currently, it uses vim.deepcopy which can be expensive and cause issues for certain table structures:

function M.mutate(key, mutator)
  if _state[key] == nil then
    _state[key] = {} --[[@as std.RawGet<OpencodeStateData, K>]]
  end

  if type(_state[key]) ~= 'table' then
    error('State key is not a table: ' .. key)
  end

  local current = _state[key]
  local old = vim.deepcopy(current) -- Deep copy here
  mutator(current)
  queue_emit(key, current, old)
  return current
end

To replace it with a shallow copy, you can iterate over the table's key-value pairs or use vim.tbl_extend (if it's a dictionary-like table). A safe approach for both arrays and dictionaries is a simple loop:

function M.mutate(key, mutator)
  if _state[key] == nil then
    _state[key] = {} --[[@as std.RawGet<OpencodeStateData, K>]]
  end

  if type(_state[key]) ~= 'table' then
    error('State key is not a table: ' .. key)
  end

  local current = _state[key]
  
  -- Shallow copy replacement
  local old = {}
  for k, v in pairs(current) do
    old[k] = v
  end

  mutator(current)
  queue_emit(key, current, old)
  return current
end

If you would like me to create a pull request to make this change for you on the sudo-tee/opencode.nvim repository, just let me know!

User: No use vim.tbl extend

Assistant: Got it! You can use vim.tbl_extend with the 'force' behavior to create a shallow copy into a new empty table.

Here is the updated mutate function using vim.tbl_extend:

function M.mutate(key, mutator)
  if _state[key] == nil then
    _state[key] = {} --[[@as std.RawGet<OpencodeStateData, K>]]
  end

  if type(_state[key]) ~= 'table' then
    error('State key is not a table: ' .. key)
  end

  local current = _state[key]
  
  -- Shallow copy using vim.tbl_extend
  local old = vim.tbl_extend('force', {}, current)
  
  mutator(current)
  queue_emit(key, current, old)
  return current
end

If you'd like me to open a pull request to apply this fix to the sudo-tee/opencode.nvim repository and resolve issue #331, just let me know!

User: Yes open a PR please

Assistant: We're currently waiting for your response in the dialog to accept or reject the creation of this pull request.

This pull request was created from Copilot chat.

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