feat: Reverse path transformation function for server config

Author: sei-dwtompkins

README.md

@@ -869,18 +869,57 @@ require('opencode').setup({
 })
 ```
 
-For WSL or complex mappings, use a function:
+### Auto-Spawning with WSL
+
+Run opencode server inside WSL while using Neovim on Windows:
 
 ```lua
 require('opencode').setup({
   server = {
     url = 'localhost',
-    port = 8080,
+    port = 'auto',  -- Random port for project isolation
+    
+    -- Spawn opencode server inside WSL
+    spawn_command = function(port, url)
+      local cmd = string.format(
+        'wsl.exe -e bash -c "opencode serve --hostname 127.0.0.1 --port %d"',
+        port
+      )
+      print(string.format('[opencode.nvim] Starting WSL server on port %d', port))
+      return vim.fn.jobstart(cmd, { detach = 1 })
+    end,
+    
+    -- Kill WSL opencode process
+    kill_command = function(port, url)
+      print(string.format('[opencode.nvim] Stopping WSL server on port %d', port))
+      vim.fn.jobstart('wsl.exe -e pkill -f "opencode serve.*--port ' .. port .. '"')
+    end,
+    
+    -- Windows → WSL path translation (for requests)
     path_map = function(host_path)
-      -- Convert Windows path to WSL path
-      local wsl_path = host_path:gsub('^C:', '/mnt/c')
-      return wsl_path
+      if vim.fn.has('win32') == 1 then
+        -- Convert C:\Users\... → /mnt/c/Users/...
+        local drive, rest = host_path:match('^([A-Za-z]):(.*)$')
+        if drive then
+          local wsl_path = '/mnt/' .. drive:lower() .. rest:gsub('\\', '/')
+          return wsl_path
+        end
+      end
+      return host_path
+    end,
+    
+    -- WSL → Windows path translation (for responses)
+    reverse_path_map = function(server_path)
+      -- Convert /mnt/c/Users/... → C:\Users\...
+      local drive, rest = server_path:match('^/mnt/([a-z])(.*)$')
+      if drive then
+        local windows_path = drive:upper() .. ':' .. rest:gsub('/', '\\')
+        return windows_path
+      end
+      return server_path
     end,
+    
+    auto_kill = true,  -- Kill server when last nvim instance exits
   },
 })
 ```
@@ -893,7 +932,8 @@ require('opencode').setup({
 - `spawn_command` (function | nil): Optional function to start server: `function(port, url) ... end`
 - `kill_command` (function | nil): Optional function to stop server when `auto_kill` triggers: `function(port, url) ... end`
 - `auto_kill` (boolean): Kill spawned servers when last nvim instance exits (default: true)
-- `path_map` (string | function | nil): Transform host paths to server paths
+- `path_map` (string | function | nil): Transform host paths to server paths (for outgoing requests)
+- `reverse_path_map` (function | nil): Transform server paths back to host paths (for incoming responses/events)
 
 ### Multi-Instance Support
 

lua/opencode/api_client.lua

@@ -3,6 +3,7 @@ local state = require('opencode.state')
 local config = require('opencode.config')
 local url_encode = require('opencode.util').url_encode
 local apply_path_map = require('opencode.util').apply_path_map
+local reverse_transform_paths_recursive = require('opencode.util').reverse_transform_paths_recursive
 
 --- Transform file paths in API payloads using configured path_map
 --- @param data any The data to transform (table, string, or other)
@@ -110,7 +111,10 @@ function OpencodeApiClient:_call(endpoint, method, body, query)
     body = transform_paths_recursive(body)
   end
 
-  return server_job.call_api(url, method, body)
+  local Promise = require('opencode.promise')
+  return server_job.call_api(url, method, body):and_then(function(result)
+    return reverse_transform_paths_recursive(result)
+  end)
 end
 
 -- Project endpoints
@@ -471,7 +475,8 @@ function OpencodeApiClient:subscribe_to_events(directory, on_event)
     chunk = chunk:gsub('^data:%s*', '')
     local ok, event = pcall(vim.json.decode, vim.trim(chunk))
     if ok and event then
-      on_event(event --[[@as table]])
+      local transformed_event = reverse_transform_paths_recursive(event)
+      on_event(transformed_event --[[@as table]])
     end
   end)
 end

lua/opencode/config.lua

@@ -25,6 +25,9 @@ M.defaults = {
     path_map = function(path)
       return path
     end,
+    reverse_path_map = function(path)
+      return path
+    end,
   },
   keymap = {
     editor = {

lua/opencode/types.lua

@@ -120,6 +120,7 @@
 ---@field kill_command fun(port: number, url: string): nil | nil -- Optional function to stop the server when auto_kill is true
 ---@field auto_kill boolean -- Kill spawned servers when nvim exits (default: true)
 ---@field path_map string | fun(host_path: string): string | nil -- Map host paths to server paths
+---@field reverse_path_map fun(server_path: string): string | nil -- Map server paths back to host paths
 
 ---@class OpencodeUIConfig
 ---@field enable_treesitter_markdown boolean

lua/opencode/util.lua

@@ -138,6 +138,52 @@ function M.apply_path_map(path)
   return path
 end
 
+function M.apply_reverse_path_map(path)
+  if not path then
+    return path
+  end
+  
+  local config = require('opencode.config')
+  local reverse_path_map = config.server.reverse_path_map
+  
+  if type(reverse_path_map) == 'function' then
+    local ok, result = pcall(reverse_path_map, path)
+    if ok and result then
+      return result
+    end
+    return path
+  end
+  
+  return path
+end
+
+function M.reverse_transform_paths_recursive(data)
+  if type(data) ~= 'table' then
+    return data
+  end
+
+  local result = {}
+  for key, value in pairs(data) do
+    if type(value) == 'string' and (
+      key == 'filePath' or 
+      key == 'path' or 
+      key == 'file' or
+      key == 'directory' or
+      key == 'cwd' or
+      key == 'root'
+    ) then
+      result[key] = M.apply_reverse_path_map(value)
+    elseif type(value) == 'table' and (key == 'files' or key == 'deleted_files') then
+      result[key] = vim.tbl_map(M.apply_reverse_path_map, value)
+    elseif type(value) == 'table' then
+      result[key] = M.reverse_transform_paths_recursive(value)
+    else
+      result[key] = value
+    end
+  end
+  return result
+end
+
 --- Format a timestamp as time (e.g., "10:23 AM",  "13 Oct 03:32 PM"  "13 Oct 2025 03:32 PM")
 --- @param timestamp number
 --- @return string: Formatted time string