feat: restore buffers after loading a session

doc/nvim-tree-lua.txt

@@ -1911,6 +1911,13 @@ Config: experimental                           *nvim-tree-config-experimental*
     In the event of a problem please disable the experiment and raise an
     issue.
 
+    Fields: ~
+      • {session_restore_nvim}?  (`boolean`, default: `false`) Restore
+                                 nvim-tree buffers when restoring vim sessions
+                                 (requires 0.13+). To restore the working
+                                 directory, ensure that |'sessionoptions'|
+                                 includes "globals"
+
 ==============================================================================
 Config: log                                             *nvim-tree-config-log*
 
@@ -2216,6 +2223,7 @@ Following is the default configuration, see |nvim_tree.config| for details. >lua
         persist = false,
       },
       experimental = {
+        session_restore_nvim = false
       },
       log = {
         enable = false,

lua/nvim-tree/_meta/config/experimental.lua

@@ -9,6 +9,10 @@ error("Cannot require a meta file")
 ---
 ---@class nvim_tree.config.experimental
 ---
+---Restore nvim-tree buffers when restoring vim sessions (requires 0.13+).
+---To restore the working directory, ensure that |'sessionoptions'| includes "globals"
+---(default: `false`)
+---@field session_restore_nvim? boolean
 --Example below for future reference:
 --
 --Buffers opened by nvim-tree will use with relative paths instead of absolute.

lua/nvim-tree/autocmd.lua

@@ -17,6 +17,58 @@ function M.global()
     end,
   })
 
+  if vim.fn.has("nvim-0.13") == 1 and config.g.experimental.session_restore_nvim then
+    vim.api.nvim_create_autocmd("SessionWritePre", { ---@diagnostic disable-line: param-type-mismatch
+      group = augroup_id,
+      callback = function()
+        local cwd = require("nvim-tree.core").get_cwd()
+        vim.g.NvimTreeState = vim.json.encode({ cwd = cwd })
+      end,
+    })
+
+    vim.api.nvim_create_autocmd("SessionLoadPost", {
+      group = augroup_id,
+      callback = function()
+        local api = require("nvim-tree.api").tree
+
+        ---@type table<integer,boolean>
+        local tabs = {}
+
+        local session_state = vim.json.decode(vim.g.NvimTreeState or "{}") or {}
+        local path = session_state and session_state.cwd or nil
+
+        -- Save tabs with leftover nvim-tree buffers
+        for _, tab in ipairs(vim.api.nvim_list_tabpages()) do
+          for _, win in ipairs(vim.api.nvim_tabpage_list_wins(tab)) do
+            local buf = vim.api.nvim_win_get_buf(win)
+            if api.is_tree_buf(buf) then
+              tabs[tab] = true
+            end
+          end
+        end
+
+        -- The new window may inherit options from the current one if we don't schedule
+        vim.schedule(function()
+          api.close_in_all_tabs()
+
+          for tab, _ in pairs(tabs) do
+            if vim.api.nvim_tabpage_is_valid(tab) then
+              local win = vim.api.nvim_tabpage_get_win(tab)
+
+              -- Invoke `open` from each tab's current window to prevent having to switch tabs
+              if vim.api.nvim_win_is_valid(win) then
+                vim.api.nvim_win_call(win, function()
+                  api.open({ path = path })
+                end)
+              end
+            end
+          end
+        end)
+      end,
+    })
+  end
+
+
   if config.g.tab.sync.open then
     vim.api.nvim_create_autocmd("TabEnter", {
       group = augroup_id,

lua/nvim-tree/config.lua

@@ -297,6 +297,7 @@ M.d = { -- config-default-start
     persist = false,
   },
   experimental = {
+    session_restore_nvim = false
   },
   log = {
     enable = false,