diff --git a/.ruby-version b/.ruby-version
new file mode 100644
index 0000000..4d54dad
--- /dev/null
+++ b/.ruby-version
@@ -0,0 +1 @@
+4.0.2
diff --git a/README.md b/README.md
index 332c144..0dd4178 100644
--- a/README.md
+++ b/README.md
@@ -124,6 +124,8 @@ Variables:
 
 CLI flags override environment variables.
 
+When `--env-file` is omitted, `codex-notify` first looks for `.env` in the current working directory and then falls back to the tool's own project root. This helps hook mode when the executable is launched from another repository.
+
 ## Usage
 
 Install dependencies first:
@@ -157,6 +159,7 @@ Run `codex-notify` separately:
 ```
 
 The entrypoint loads `bundler/setup`, so `bundle exec` is not required after `bundle install`.
+If `rbenv` is available, the entrypoint re-execs itself with the Ruby version from this project's `.ruby-version`, even when launched from another repository.
 
 Monitor a specific session file:
 
@@ -310,6 +313,7 @@ Notes:
 - `SessionStart`, `UserPromptSubmit`, `PreToolUse`, `PostToolUse`, and `Stop` are the event names.
 - In hook mode, a prompt containing only `---` clears the saved Slack thread for that Codex session. The next user prompt starts a new Slack thread.
 - This executable pins `BUNDLE_GEMFILE` to its own project, so it can be launched from other repositories without resolving the wrong `Gemfile`.
+- If `rbenv` is installed, the executable also re-execs with the Ruby version declared in this project's `.ruby-version`, so another repository's `.ruby-version` does not take precedence.
 - The hook implementation keeps normal successful runs quiet so Codex does not show extra debug-style output from the hook itself.
 
 Hook mode does not require `--no-alt-screen`, because it does not depend on session-log tailing.
diff --git a/bin/codex-notify b/bin/codex-notify
index 7d589da..fd9928e 100755
--- a/bin/codex-notify
+++ b/bin/codex-notify
@@ -1,11 +1,27 @@
 #!/usr/bin/env ruby
 # frozen_string_literal: true
 
-ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)
+root = File.expand_path('..', __dir__)
+ruby_version_file = File.join(root, '.ruby-version')
+
+if ENV['CODEX_NOTIFY_RBENV_REEXEC'] != '1' && File.exist?(ruby_version_file)
+  begin
+    if system('rbenv', 'version-name', out: File::NULL, err: File::NULL)
+      ENV['RBENV_DIR'] = root
+      ENV['BUNDLE_GEMFILE'] = File.join(root, 'Gemfile')
+      ENV['CODEX_NOTIFY_RBENV_REEXEC'] = '1'
+      exec('rbenv', 'exec', 'ruby', __FILE__, *ARGV)
+    end
+  rescue StandardError
+    nil
+  end
+end
+
+ENV['BUNDLE_GEMFILE'] ||= File.join(root, 'Gemfile')
 
 require 'bundler/setup'
 
-$LOAD_PATH.unshift(File.expand_path('../lib', __dir__))
+$LOAD_PATH.unshift(File.join(root, 'lib'))
 
 require 'codex_notify'
 
diff --git a/bin/codex-notify-hook b/bin/codex-notify-hook
index 465c072..b00881b 100755
--- a/bin/codex-notify-hook
+++ b/bin/codex-notify-hook
@@ -1,10 +1,26 @@
 #!/usr/bin/env ruby
 # frozen_string_literal: true
 
-ENV['BUNDLE_GEMFILE'] ||= File.expand_path('../Gemfile', __dir__)
+root = File.expand_path('..', __dir__)
+ruby_version_file = File.join(root, '.ruby-version')
+
+if ENV['CODEX_NOTIFY_RBENV_REEXEC'] != '1' && File.exist?(ruby_version_file)
+  begin
+    if system('rbenv', 'version-name', out: File::NULL, err: File::NULL)
+      ENV['RBENV_DIR'] = root
+      ENV['BUNDLE_GEMFILE'] = File.join(root, 'Gemfile')
+      ENV['CODEX_NOTIFY_RBENV_REEXEC'] = '1'
+      exec('rbenv', 'exec', 'ruby', __FILE__, *ARGV)
+    end
+  rescue StandardError
+    nil
+  end
+end
+
+ENV['BUNDLE_GEMFILE'] ||= File.join(root, 'Gemfile')
 
 require 'bundler/setup'
-$LOAD_PATH.unshift(File.expand_path('../lib', __dir__))
+$LOAD_PATH.unshift(File.join(root, 'lib'))
 
 require 'codex_notify/hook_cli'
 
diff --git a/lib/codex_notify/config.rb b/lib/codex_notify/config.rb
index 782999c..f96198e 100644
--- a/lib/codex_notify/config.rb
+++ b/lib/codex_notify/config.rb
@@ -9,6 +9,7 @@ module CodexNotify
   module Config
     DEFAULT_ENV_PATH = '.env'
     DEFAULT_SESSIONS_DIR = Pathname(File.expand_path('~/.codex/sessions'))
+    APP_ROOT = Pathname(__dir__).join('../..').expand_path
 
     Args = Struct.new(
       :env_file,
@@ -28,8 +29,20 @@ module Config
 
     module_function
 
-    def load_env_file(path = DEFAULT_ENV_PATH, override: false)
+    def app_root
+      APP_ROOT
+    end
+
+    def resolve_env_path(path = DEFAULT_ENV_PATH)
       env_path = Pathname(path)
+      return env_path if env_path.absolute?
+
+      [Pathname(Dir.pwd).join(env_path), app_root.join(env_path)].find(&:exist?)
+    end
+
+    def load_env_file(path = DEFAULT_ENV_PATH, override: false)
+      env_path = resolve_env_path(path)
+      return unless env_path
       return unless env_path.exist?
 
       loader = override ? Dotenv.method(:overload) : Dotenv.method(:load)
diff --git a/lib/codex_notify/hook_config.rb b/lib/codex_notify/hook_config.rb
index 01e8ef3..65b5628 100644
--- a/lib/codex_notify/hook_config.rb
+++ b/lib/codex_notify/hook_config.rb
@@ -9,6 +9,7 @@ module CodexNotify
   module HookConfig
     DEFAULT_ENV_PATH = '.env'
     DEFAULT_STATE_PATH = Pathname(File.expand_path('~/.codex-notify-hook/state.json'))
+    APP_ROOT = Pathname(__dir__).join('../..').expand_path
 
     Args = Struct.new(
       :env_file,
@@ -23,8 +24,20 @@ module HookConfig
 
     module_function
 
-    def load_env_file(path = DEFAULT_ENV_PATH, override: false)
+    def app_root
+      APP_ROOT
+    end
+
+    def resolve_env_path(path = DEFAULT_ENV_PATH)
       env_path = Pathname(path)
+      return env_path if env_path.absolute?
+
+      [Pathname(Dir.pwd).join(env_path), app_root.join(env_path)].find(&:exist?)
+    end
+
+    def load_env_file(path = DEFAULT_ENV_PATH, override: false)
+      env_path = resolve_env_path(path)
+      return unless env_path
       return unless env_path.exist?
 
       loader = override ? Dotenv.method(:overload) : Dotenv.method(:load)
diff --git a/test/test_config.rb b/test/test_config.rb
index c07932b..1ea7d02 100644
--- a/test/test_config.rb
+++ b/test/test_config.rb
@@ -62,6 +62,33 @@ def test_parse_args_uses_env_file_defaults
     end
   end
 
+  def test_load_env_file_falls_back_to_app_root_for_relative_path
+    with_tmpdir do |dir|
+      env_file = dir.join('.env')
+      env_file.write("SLACK_BOT_TOKEN=xoxb-app-root\nSLACK_CHANNEL=CROOT\n")
+      ENV.delete('SLACK_BOT_TOKEN')
+      ENV.delete('SLACK_CHANNEL')
+
+      original = Config.method(:app_root)
+      Dir.mktmpdir do |cwd|
+        Dir.chdir(cwd) do
+          with_silenced_warnings do
+            Config.singleton_class.send(:define_method, :app_root) { dir }
+          end
+
+          Config.load_env_file('.env')
+        end
+      end
+    ensure
+      with_silenced_warnings do
+        Config.singleton_class.send(:define_method, :app_root, original)
+      end
+    end
+
+    assert_equal 'xoxb-app-root', ENV['SLACK_BOT_TOKEN']
+    assert_equal 'CROOT', ENV['SLACK_CHANNEL']
+  end
+
   def test_parse_args_prefers_cli_user_name_over_env
     ENV['CODEX_NOTIFY_USER_NAME'] = 'env-user'
 
diff --git a/test/test_hook_config.rb b/test/test_hook_config.rb
new file mode 100644
index 0000000..ddcc5ec
--- /dev/null
+++ b/test/test_hook_config.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require 'tmpdir'
+require_relative 'test_helper'
+
+class CodexNotifyHookConfigTest < Minitest::Test
+  HookConfig = CodexNotify::HookConfig
+
+  def setup
+    @env_backup = ENV.to_h
+  end
+
+  def teardown
+    ENV.replace(@env_backup)
+  end
+
+  def test_parse_args_falls_back_to_app_root_env_for_relative_path
+    with_tmpdir do |dir|
+      env_file = dir.join('.env')
+      env_file.write("SLACK_BOT_TOKEN=xoxb-hook\nSLACK_CHANNEL=CHOOK\nCODEX_NOTIFY_USER_NAME=hook-user\n")
+      ENV.delete('SLACK_BOT_TOKEN')
+      ENV.delete('SLACK_CHANNEL')
+      ENV.delete('CODEX_NOTIFY_USER_NAME')
+
+      original = HookConfig.method(:app_root)
+      Dir.mktmpdir do |cwd|
+        Dir.chdir(cwd) do
+          with_silenced_warnings do
+            HookConfig.singleton_class.send(:define_method, :app_root) { dir }
+          end
+
+          args = HookConfig.parse_args([])
+          assert_equal 'xoxb-hook', args.token
+          assert_equal 'CHOOK', args.channel
+          assert_equal 'hook-user', args.user_name
+        end
+      end
+    ensure
+      with_silenced_warnings do
+        HookConfig.singleton_class.send(:define_method, :app_root, original)
+      end
+    end
+  end
+
+  private
+
+  def with_tmpdir
+    Dir.mktmpdir do |dir|
+      yield Pathname(dir)
+    end
+  end
+
+  def with_silenced_warnings
+    original_verbose = $VERBOSE
+    $VERBOSE = nil
+    yield
+  ensure
+    $VERBOSE = original_verbose
+  end
+end