fix: properly render anthropic tool results while restoring chats

[ravitemer]

Description

This is related to the ravitemer/codecompanion-history.nvim#43 issue at the history extension.

For the anthropic adapter, the content field of a tool result message is a table rather than a plain string e.g:

{
    content = {
      content = "**`neovim__list_directory` Tool**: Returned the following:\n\n````\n Directory Listing: ````",
      is_error = false,
      tool_use_id = "toolu_012TCg3Xi16Ef8fPdhafFynS",
      type = "tool_result"
    },
    cycle = 2,
    id = 2082665656,
    opts = {
      visible = true
    },
    role = "tool"
  }, 

This leads to issues while restoring the chat with messages of this kind while rendering that chat buffer as we assume msg.content will always be a string as follows previously:

codecompanion.nvim/lua/codecompanion/strategies/chat/ui/init.lua

Lines 282 to 285 in 53b6f50

	local trimempty = not (msg.role == "user" and msg.content == "")
	for _, text in ipairs(vim.split(msg.content or "", "\n", { plain = true, trimempty = trimempty })) do
	table.insert(lines, text)
	end

This PR handles checks for msg.content.content field to handle the special anthropic case.

Related Issue(s)

ravitemer/codecompanion-history.nvim#43

Screenshots

Checklist

• I've read the contributing guidelines and have adhered to them in this PR
• I've updated CodeCompanion.has in the init.lua file for my new feature
• I've added test coverage for this fix/feature
• I've updated the README and/or relevant docs pages
• I've run make all to ensure docs are generated, tests pass and my formatting is applied

[amadeus]

Any movement on this? It essentially means we can't use the history plugin with any anthropic models that utilize a file tool of some kind, which is kind of a bummer.

This is what happens when it tries to resume a saved chat: