feat: system instructions (#81)

Author: azorng

README.md

@@ -119,7 +119,8 @@ require('goose').setup({
       "cogito:14b"
     }
     --]]
-  }
+  },
+  system_instructions = ""    -- Provide additional system instructions to customize the agent's behavior
 })
 ```
 

lua/goose/config.lua

@@ -67,6 +67,7 @@ M.defaults = {
   context = {
     cursor_data = false, -- Send cursor position and current line content as context data
   },
+  system_instructions = "", -- Provide additional system instructions to customize the agent's behavior
 }
 
 -- Active configuration

lua/goose/job.lua

@@ -3,6 +3,7 @@
 
 local context = require("goose.context")
 local state = require("goose.state")
+local config = require("goose.config")
 local Job = require('plenary.job')
 
 local M = {}
@@ -12,6 +13,12 @@ function M.build_args(prompt)
   local message = context.format_message(prompt)
   local args = { "run", "--text", message }
 
+  local system_instructions = config.get("system_instructions")
+  if system_instructions and system_instructions ~= "" then
+    table.insert(args, "--system")
+    table.insert(args, system_instructions)
+  end
+
   if state.active_session then
     table.insert(args, "--name")
     table.insert(args, state.active_session.name)