feat(config): add per-host/bucket extra args for SSH, S3, and FTP

Problem: `extra_scp_args`, `extra_s3_args`, and `extra_curl_args` are
global — there's no way to pass adapter-specific args only to a single
host or bucket (e.g. `-O` for a Synology NAS that requires legacy SCP
protocol, or `--endpoint-url` for an R2 bucket).

Solution: add `ssh_hosts`, `s3_buckets`, and `ftp_hosts` config tables
that map exact hostnames/bucket names to per-target arg lists. Per-target
args are appended after the global args at call time. The `scp()` helper
in `ssh.lua` accepts a `hosts` list so cross-host copies deduplicate
host lookups. `create_s3_command` in `s3fs.lua` extracts the bucket from
the command args with no call-site changes needed. `resolved_curl_args`
in `ftp.lua` is called by both `curl()` and `ftpcmd()`.

Based on: stevearc/oil.nvim#607

lua/oil/adapters/ftp.lua

@@ -106,6 +106,17 @@ local function curl_ftp_url(url)
   return table.concat(pieces, '')
 end
 
+---@param host string
+---@return string[]
+local function resolved_curl_args(host)
+  local extra = vim.deepcopy(config.extra_curl_args)
+  local host_cfg = config.ftp_hosts[host]
+  if host_cfg and host_cfg.extra_curl_args then
+    vim.list_extend(extra, host_cfg.extra_curl_args)
+  end
+  return extra
+end
+
 ---@param url oil.ftpUrl
 ---@param py_lines string[]
 ---@param cb fun(err: nil|string)
@@ -113,8 +124,8 @@ local function ftpcmd(url, py_lines, cb)
   local lines = {}
   local use_tls = url.scheme == 'oil-ftps://'
   if use_tls then
-    local insecure = vim.tbl_contains(config.extra_curl_args, '--insecure')
-      or vim.tbl_contains(config.extra_curl_args, '-k')
+    local curl_args = resolved_curl_args(url.host)
+    local insecure = vim.tbl_contains(curl_args, '--insecure') or vim.tbl_contains(curl_args, '-k')
     table.insert(lines, 'import ftplib, ssl')
     table.insert(lines, 'ctx = ssl.create_default_context()')
     if insecure then
@@ -170,7 +181,7 @@ local function curl(url, extra_args, opts, cb)
   end
   local cmd = { 'curl', '-sS', '--netrc-optional' }
   vim.list_extend(cmd, ssl_args(url))
-  vim.list_extend(cmd, config.extra_curl_args)
+  vim.list_extend(cmd, resolved_curl_args(url.host))
   vim.list_extend(cmd, extra_args)
   shell.run(cmd, opts, cb)
 end

lua/oil/adapters/s3/s3fs.lua

@@ -46,8 +46,22 @@ end
 ---@param cmd string[] cmd and flags
 ---@return string[] Shell command to run
 local function create_s3_command(cmd)
+  local bucket
+  for _, arg in ipairs(cmd) do
+    bucket = arg:match('^s3://([^/]+)')
+    if bucket then
+      break
+    end
+  end
+  local extra = vim.deepcopy(config.extra_s3_args)
+  if bucket then
+    local bucket_cfg = config.s3_buckets[bucket]
+    if bucket_cfg and bucket_cfg.extra_s3_args then
+      vim.list_extend(extra, bucket_cfg.extra_s3_args)
+    end
+  end
   local full_cmd = vim.list_extend({ 'aws', 's3' }, cmd)
-  return vim.list_extend(full_cmd, config.extra_s3_args)
+  return vim.list_extend(full_cmd, extra)
 end
 
 ---@param url string

lua/oil/adapters/ssh.lua

@@ -21,9 +21,21 @@ local FIELD_META = constants.FIELD_META
 ---@field port nil|integer
 ---@field path string
 
+---@param hosts string[]
 ---@param args string[]
-local function scp(args, ...)
-  local cmd = vim.list_extend({ 'scp', '-C' }, config.extra_scp_args)
+local function scp(hosts, args, ...)
+  local extra = vim.deepcopy(config.extra_scp_args)
+  local seen = {}
+  for _, host in ipairs(hosts) do
+    if not seen[host] then
+      seen[host] = true
+      local host_cfg = config.ssh_hosts[host]
+      if host_cfg and host_cfg.extra_scp_args then
+        vim.list_extend(extra, host_cfg.extra_scp_args)
+      end
+    end
+  end
+  local cmd = vim.list_extend({ 'scp', '-C' }, extra)
   vim.list_extend(cmd, args)
   shell.run(cmd, ...)
 end
@@ -320,12 +332,16 @@ M.perform_action = function(action, cb)
       local src_conn = get_connection(action.src_url)
       local dest_conn = get_connection(action.dest_url)
       if src_conn ~= dest_conn then
-        scp({ '-r', url_to_scp(src_res), url_to_scp(dest_res) }, function(err)
-          if err then
-            return cb(err)
+        scp(
+          { src_res.host, dest_res.host },
+          { '-r', url_to_scp(src_res), url_to_scp(dest_res) },
+          function(err)
+            if err then
+              return cb(err)
+            end
+            src_conn:rm(src_res.path, cb)
           end
-          src_conn:rm(src_res.path, cb)
-        end)
+        )
       else
         src_conn:mv(src_res.path, dest_res.path, cb)
       end
@@ -339,26 +355,31 @@ M.perform_action = function(action, cb)
       local src_res = M.parse_url(action.src_url)
       local dest_res = M.parse_url(action.dest_url)
       if not url_hosts_equal(src_res, dest_res) then
-        scp({ '-r', url_to_scp(src_res), url_to_scp(dest_res) }, cb)
+        scp(
+          { src_res.host, dest_res.host },
+          { '-r', url_to_scp(src_res), url_to_scp(dest_res) },
+          cb
+        )
       else
         local src_conn = get_connection(action.src_url)
         src_conn:cp(src_res.path, dest_res.path, cb)
       end
     else
-      local src_arg
-      local dest_arg
       if src_adapter == M then
-        src_arg = url_to_scp(M.parse_url(action.src_url))
+        local src_res = M.parse_url(action.src_url)
+        local src_arg = url_to_scp(src_res)
         local _, path = util.parse_url(action.dest_url)
         assert(path)
-        dest_arg = fs.posix_to_os_path(path)
+        local dest_arg = fs.posix_to_os_path(path)
+        scp({ src_res.host }, { '-r', src_arg, dest_arg }, cb)
       else
         local _, path = util.parse_url(action.src_url)
         assert(path)
-        src_arg = fs.posix_to_os_path(path)
-        dest_arg = url_to_scp(M.parse_url(action.dest_url))
+        local src_arg = fs.posix_to_os_path(path)
+        local dest_res = M.parse_url(action.dest_url)
+        local dest_arg = url_to_scp(dest_res)
+        scp({ dest_res.host }, { '-r', src_arg, dest_arg }, cb)
       end
-      scp({ '-r', src_arg, dest_arg }, cb)
     end
   else
     cb(string.format('Bad action type: %s', action.type))
@@ -384,7 +405,7 @@ M.read_file = function(bufnr)
   end
   local tmp_bufnr = vim.fn.bufadd(tmpfile)
 
-  scp({ scp_url, tmpfile }, function(err)
+  scp({ url.host }, { scp_url, tmpfile }, function(err)
     loading.set_loading(bufnr, false)
     vim.bo[bufnr].modifiable = true
     vim.cmd.doautocmd({ args = { 'BufReadPre', bufname }, mods = { silent = true } })
@@ -426,7 +447,7 @@ M.write_file = function(bufnr)
   vim.cmd.write({ args = { tmpfile }, bang = true, mods = { silent = true, noautocmd = true } })
   local tmp_bufnr = vim.fn.bufadd(tmpfile)
 
-  scp({ tmpfile, scp_url }, function(err)
+  scp({ url.host }, { tmpfile, scp_url }, function(err)
     vim.bo[bufnr].modifiable = true
     if err then
       vim.notify(string.format('Error writing file: %s', err), vim.log.levels.ERROR)