fix(snacks): track job PID to ensure process cleanup on exit

The snacks.terminal.list() is empty during VimLeavePre because snacks
cleans up its terminal tracking before that event fires. However, the
underlying process is not killed.

This fix:
- Captures the job ID and PID when the terminal starts
- Uses the stored PID to kill the process directly during stop()
- Falls back to snacks.terminal.list() for normal operation
- Uses both SIGTERM and SIGKILL to ensure the process is terminated

Author: pedropombeiro

lua/opencode/provider/snacks.lua

@@ -4,6 +4,8 @@
 ---@class opencode.provider.Snacks : opencode.Provider
 ---
 ---@field opts snacks.terminal.Opts
+---@field private _job_id number|nil
+---@field private _pid number|nil
 local Snacks = {}
 Snacks.__index = Snacks
 Snacks.name = "snacks"
@@ -15,6 +17,8 @@ Snacks.name = "snacks"
 function Snacks.new(opts)
   local self = setmetatable({}, Snacks)
   self.opts = opts or {}
+  self._job_id = nil
+  self._pid = nil
   return self
 end
 
@@ -49,23 +53,46 @@ end
 function Snacks:start()
   if not self:get() then
     require("snacks.terminal").open(self.cmd, self.opts)
+    -- Capture the job ID and PID after terminal opens
+    vim.defer_fn(function()
+      local win = self:get()
+      if win and win.buf and vim.api.nvim_buf_is_valid(win.buf) then
+        self._job_id = vim.b[win.buf].terminal_job_id
+        if self._job_id then
+          self._pid = vim.fn.jobpid(self._job_id)
+        end
+      end
+    end, 100)
   end
 end
 
 function Snacks:stop()
-  -- Iterate all snacks terminals to find ours, since `self:get()` uses cwd
-  -- in the terminal ID and may not find it if cwd changed.
+  -- Try to stop via the tracked job ID (more reliable than snacks.terminal.list()
+  -- which may be empty during VimLeavePre)
+  if self._job_id then
+    local ok, _ = pcall(vim.fn.jobstop, self._job_id)
+    -- If jobstop failed, fall back to kill
+    if not ok and self._pid then
+      os.execute("kill " .. tostring(self._pid) .. " 2>/dev/null")
+      os.execute("kill -9 " .. tostring(self._pid) .. " 2>/dev/null")
+    end
+  end
+
+  -- Also try via snacks list to close the window
   for _, win in pairs(require("snacks.terminal").list()) do
     if win.cmd == self.cmd then
       if win.buf and vim.api.nvim_buf_is_valid(win.buf) then
         local job_id = vim.b[win.buf].terminal_job_id
         if job_id then
-          vim.fn.jobstop(job_id)
+          pcall(vim.fn.jobstop, job_id)
         end
       end
       win:close()
     end
   end
+
+  self._job_id = nil
+  self._pid = nil
 end
 
 return Snacks