feat: add support for per-agent configuration

README.md

@@ -222,6 +222,18 @@ Default "noop" agent is `copilot`.
 For more information about extension agents, see [here](https://docs.github.com/en/copilot/using-github-copilot/using-extensions-to-integrate-external-tools-with-copilot-chat)  
 You can install more agents from [here](https://github.com/marketplace?type=apps&copilot_app=true)
 
+You can optionally define extra per-agent configuration like this:
+
+```lua
+{
+  agents = {
+    perplexityai = {
+      model = 'llama-3.1-sonar-huge-128k-online'
+    },
+  }
+}
+```
+
 ### Contexts
 
 Contexts are used to determine the context of the chat.  
@@ -411,6 +423,7 @@ Also see [here](/lua/CopilotChat/config.lua):
 
   history_path = vim.fn.stdpath('data') .. '/copilotchat_history', -- Default path to stored history
   callback = nil, -- Callback to use when ask response is received
+  agents = nil, -- default per agent configuration
 
   -- default selection
   selection = function(source)

lua/CopilotChat/config.lua

@@ -90,6 +90,7 @@ local select = require('CopilotChat.select')
 ---@field highlight_headers boolean?
 ---@field history_path string?
 ---@field callback fun(response: string, source: CopilotChat.config.source)?
+---@field agents table<string, table>?
 ---@field selection nil|fun(source: CopilotChat.config.source):CopilotChat.config.selection?
 ---@field contexts table<string, CopilotChat.config.context>?
 ---@field prompts table<string, CopilotChat.config.prompt|string>?
@@ -124,6 +125,7 @@ return {
 
   history_path = vim.fn.stdpath('data') .. '/copilotchat_history', -- Default path to stored history
   callback = nil, -- Callback to use when ask response is received
+  agents = nil, -- default per agent configuration
 
   -- default selection
   selection = function(source)

lua/CopilotChat/copilot.lua

@@ -10,6 +10,7 @@
 ---@field model string?
 ---@field agent string?
 ---@field temperature number?
+---@field extra_body table?
 ---@field on_progress nil|fun(response: string):nil
 
 ---@class CopilotChat.copilot.embed.opts
@@ -707,19 +708,23 @@ function Copilot:ask(prompt, opts)
     full_response = full_response .. content
   end
 
-  local body = vim.json.encode(
-    generate_ask_request(
-      self.history,
-      prompt,
-      system_prompt,
-      generated_messages,
-      model,
-      temperature,
-      max_output_tokens,
-      not vim.startswith(model, 'o1')
-    )
+  local request = generate_ask_request(
+    self.history,
+    prompt,
+    system_prompt,
+    generated_messages,
+    model,
+    temperature,
+    max_output_tokens,
+    not vim.startswith(model, 'o1')
   )
 
+  if opts.extra_body then
+    request = vim.tbl_extend('force', request, opts.extra_body)
+  end
+
+  local body = vim.json.encode(request)
+
   if vim.startswith(model, 'claude') then
     self:enable_claude()
   end

lua/CopilotChat/init.lua

@@ -637,6 +637,7 @@ function M.ask(prompt, config)
         model = selected_model,
         agent = selected_agent,
         temperature = config.temperature,
+        extra_body = config.agents and selected_agent and config.agents[selected_agent],
         on_progress = function(token)
           vim.schedule(function()
             state.chat:append(token)