diff --git a/doc/distribution/windows.md b/doc/distribution/windows.md
index 26a727d7adb26a..304e3451547fc6 100644
--- a/doc/distribution/windows.md
+++ b/doc/distribution/windows.md
@@ -149,6 +149,11 @@ sh ../../ruby/configure -C --disable-install-doc --with-opt-dir=C:\Users\usernam
     of `cmd.exe`.  If you want to enable it explicitly, run `cmd.exe` with
     `/E:ON` option.
 
+7.  Some tests in `nmake check` create symbolic links.  Enable
+    [Developer Mode](https://learn.microsoft.com/windows/apps/get-started/developer-mode-features-and-debugging)
+    (Settings > System > For developers) so that they do not fail with
+    `Permission denied @ rb_file_s_symlink`.
+
 ### How to compile and install
 
 1.  Execute `win32\configure.bat` on your build directory.
diff --git a/file.c b/file.c
index 1231848c1035f0..5473ee910b4e4a 100644
--- a/file.c
+++ b/file.c
@@ -1837,14 +1837,24 @@ rb_file_pipe_p(VALUE obj, VALUE fname)
 }
 
 /*
+ * :markup: markdown
+ *
  * call-seq:
- *   File.symlink?(filepath) -> true or false
+ *   File.symlink?(path) -> true or false
  *
- * Returns +true+ if +filepath+ points to a symbolic link, +false+ otherwise:
+ * Returns whether the entry at `path` is a symbolic link:
  *
- *   symlink = File.symlink('t.txt', 'symlink')
- *   File.symlink?('symlink') # => true
- *   File.symlink?('t.txt')   # => false
+ * ```ruby
+ * # Create paths.
+ * file_path = 'doc/extension.rdoc'         # => "doc/extension.rdoc"
+ * target_path = File.join('..', file_path) # => "../doc/extension.rdoc"
+ * link_path = 'lib/u.tmp'                  # => "lib/u.tmp"
+ * File.symlink?(link_path)                 # => false
+ * # Create link and verify.
+ * File.symlink(target_path, link_path)
+ * File.symlink?(link_path)                 # => true
+ * File.delete(link_path)                   # Clean up.
+ * ```
  *
  */
 
@@ -3511,15 +3521,27 @@ rb_file_s_link(VALUE klass, VALUE from, VALUE to)
 
 #ifdef HAVE_SYMLINK
 /*
+ * :markup: markdown
+ *
  *  call-seq:
- *     File.symlink(old_name, new_name)   -> 0
+ *    File.symlink(path, link_path) -> 0
  *
- *  Creates a symbolic link called <i>new_name</i> for the existing file
- *  <i>old_name</i>. Raises a NotImplemented exception on
- *  platforms that do not support symbolic links.
+ *  Not supported on some platforms.
  *
- *     File.symlink("testfile", "link2test")   #=> 0
+ *  Creates a symbolic link at `link_path` to the entry at `path`:
  *
+ *  ```ruby
+ *  # Create paths.
+ *  file_path = 'doc/extension.rdoc'             # => "doc/extension.rdoc"
+ *  target_path = File.join('..', file_path)     # => "../doc/extension.rdoc"
+ *  link_path = 'lib/u.tmp'                      # => "lib/u.tmp"
+ *  # Create link and verify.
+ *  File.symlink(target_path, link_path)
+ *  File.read(file_path) == File.read(link_path) # => true
+ *  File.delete(link_path)                       # Clean up.
+ *  ```
+ *
+ *  See also: ::read, ::readlink, ::symlink?.
  */
 
 static VALUE
@@ -3541,14 +3563,23 @@ rb_file_s_symlink(VALUE klass, VALUE from, VALUE to)
 
 #ifdef HAVE_READLINK
 /*
+ *  :markup: markdown
+ *
  *  call-seq:
- *     File.readlink(link_name)  ->  file_name
+ *     File.readlink(link_path) -> path
  *
- *  Returns the name of the file referenced by the given link.
- *  Not available on all platforms.
+ *  Returns the string path to the entry referenced by the given `link_path`:
+ *
+ *  ```ruby
+ *  # Create paths.
+ *  file_path = 'doc/extension.rdoc'         # => "doc/extension.rdoc"
+ *  target_path = File.join('..', file_path) # => "../doc/extension.rdoc"
+ *  link_path = 'lib/u.tmp'                  # => "lib/u.tmp"
+ *  File.symlink(target_path, link_path)
+ *  File.readlink(link_path)                 # => "../doc/extension.rdoc"
+ *  File.delete(link_path)                   # Clean up.
+ *  ```
  *
- *     File.symlink("testfile", "link2test")   #=> 0
- *     File.readlink("link2test")              #=> "testfile"
  */
 
 static VALUE
@@ -6415,18 +6446,24 @@ rb_stat_p(VALUE obj)
 }
 
 /*
+ *  :markup: markdown
+ *
  *  call-seq:
- *     stat.symlink?    -> true or false
+ *    symlink? -> true or false
  *
- *  Returns <code>true</code> if <i>stat</i> is a symbolic link,
- *  <code>false</code> if it isn't or if the operating system doesn't
- *  support this feature. As File::stat automatically follows symbolic
- *  links, #symlink? will always be <code>false</code> for an object
- *  returned by File::stat.
+ *  Returns whether the entry in `self` is a symbolic link:
  *
- *     File.symlink("testfile", "alink")   #=> 0
- *     File.stat("alink").symlink?         #=> false
- *     File.lstat("alink").symlink?        #=> true
+ *  ```ruby
+ *  path = 'doc/t.tmp'
+ *  link_path = 'lib/u.tmp'
+ *  File.write(path, 'foo')
+ *  File.symlink(path, link_path)
+ *  File.stat(path).symlink?       # => false
+ *  File.stat(link_path).symlink?  # Raises Errno::ENOENT; entry is not a file.
+ *  File.lstat(link_path).symlink? # => true
+ *  File.delete(path)
+ *  File.delete(link_path)
+ *  ```
  *
  */
 
diff --git a/lib/rubygems/util/atomic_file_writer.rb b/lib/rubygems/util/atomic_file_writer.rb
index 32767c6a79081d..c21b8e67193e64 100644
--- a/lib/rubygems/util/atomic_file_writer.rb
+++ b/lib/rubygems/util/atomic_file_writer.rb
@@ -26,6 +26,16 @@ def self.open(file_name)
       basename = File.basename(file_name)
       tmp_path = File.join(dirname, ".#{basename.byteslice(0, 254 - tmp_suffix.bytesize)}#{tmp_suffix}")
 
+      # The temporary name is longer than the final one, so on Windows a
+      # writable destination can still map to a path beyond the 260-character
+      # MAX_PATH limit. Only in that case, trim the random suffix just enough to
+      # fit, keeping at least 8 hex characters to avoid collisions.
+      if tmp_path.length >= 260 && Gem.win_platform?
+        keep = [tmp_suffix.bytesize - (tmp_path.length - 259), ".tmp.".bytesize + 8].max
+        tmp_suffix = tmp_suffix.byteslice(0, keep)
+        tmp_path = File.join(dirname, ".#{basename.byteslice(0, 254 - tmp_suffix.bytesize)}#{tmp_suffix}")
+      end
+
       flags = File::RDWR | File::CREAT | File::EXCL | File::BINARY
       flags |= File::SHARE_DELETE if defined?(File::SHARE_DELETE)
 
diff --git a/pathname_builtin.rb b/pathname_builtin.rb
index b12432cfb286fe..9e510eddb239a9 100644
--- a/pathname_builtin.rb
+++ b/pathname_builtin.rb
@@ -1196,7 +1196,37 @@ def birthtime() File.birthtime(@path) end
   #
   def ctime() File.ctime(@path) end
 
-  # See <tt>File.mtime</tt>.  Returns last modification time.
+  # :markup: markdown
+  #
+  # call-seq:
+  #   mtime -> time
+  #
+  # Returns a Time object containing the time of the most recent
+  # modification to the entry represented by `self`;
+  # see {File System Timestamps}[rdoc-ref:file/timestamps.md]:
+  #
+  # ```ruby
+  # # A directory and its Pathname.
+  # dir_path = 'doc/foo'
+  # dir_pn = Pathname(dir_path)
+  # # Create directory; directory mtime established.
+  # dir_pn.mkdir
+  # dir_pn.mtime  # => 2026-06-28 16:38:02.675780521 -0500
+  # # A file therein and its Pathname.
+  # file_path = dir_pn.join('t.tmp')
+  # file_pn = Pathname(file_path)
+  # # Create file; file mtime established; directory mtime updated.
+  # file_pn.write('foo')
+  # dir_pn.mtime  # => 2026-06-28 16:41:23.107750483 -0500
+  # file_pn.mtime # => 2026-06-28 16:41:23.107750483 -0500
+  # # Modify file; file mtime updated; directory mtime unchanged.
+  # file_pn.write('bar')
+  # dir_pn.mtime  # => 2026-06-28 16:41:23.107750483 -0500
+  # file_pn.mtime # => 2026-06-28 16:42:48.869163049 -0500
+  # # Clean up.
+  # dir_pn.rmtree
+  # ```
+  #
   def mtime() File.mtime(@path) end
 
 
@@ -1421,7 +1451,23 @@ def open(...) # :yield: file
     File.open(@path, ...)
   end
 
-  # See <tt>File.readlink</tt>.  Read symbolic link.
+  # :markup: markdown
+  #
+  # call-seq:
+  #   readlink -> new_pathname
+  #
+  # Returns a new pathname containing the string path to the entry referenced by `self`:
+  #
+  # ```ruby
+  # # Create Pathnames.
+  # file_pn = Pathname('doc/extension.rdoc') # => #<Pathname:doc/extension.rdoc>
+  # target_pn = Pathname('..').join(file_pn) # => #<Pathname:../doc/extension.rdoc>
+  # link_pn = Pathname('lib/u.tmp')          # => #<Pathname:lib/u.tmp>
+  # link_pn.make_symlink(target_pn)
+  # link_pn.readlink                         # => #<Pathname:../doc/extension.rdoc>
+  # link_pn.delete
+  # ```
+  #
   def readlink() self.class.new(File.readlink(@path)) end
 
   # See <tt>File.rename</tt>.  Rename the file.
@@ -1457,7 +1503,25 @@ def stat() File.stat(@path) end
   #
   def lstat() File.lstat(@path) end
 
-  # See <tt>File.symlink</tt>.  Creates a symbolic link.
+  # :markup: markdown
+  #
+  # call-seq:
+  #   make_symlink(path) -> 0
+  #
+  # Creates a symbolic link at the path in `self` to the entry at `path`:
+  #
+  # ```ruby
+  # # Create Pathnames.
+  # file_pn = Pathname('doc/extension.rdoc') # => #<Pathname:doc/extension.rdoc>
+  # target_pn = Pathname('..').join(file_pn) # => #<Pathname:../doc/extension.rdoc>
+  # link_pn = Pathname('lib/u.tmp')          # => #<Pathname:lib/u.tmp>
+  # # Create link and verify.
+  # link_pn.make_symlink(target_pn)
+  # file_pn.read == link_pn.read             # => true
+  # link_pn.delete                           # Clean up.
+  # ```
+  #
+  # See also: #read, #readlink, #symlink?.
   def make_symlink(old) File.symlink(old, @path) end
 
   # See <tt>File.truncate</tt>.  Truncate the file to +length+ bytes.
@@ -1844,11 +1908,28 @@ def size() FileTest.size(@path) end
 
   # See <tt>FileTest.size?</tt>.
   def size?() FileTest.size?(@path) end
-
   # See <tt>FileTest.sticky?</tt>.
   def sticky?() FileTest.sticky?(@path) end
 
-  # See <tt>FileTest.symlink?</tt>.
+  # :markup: markdown
+  #
+  # call-seq:
+  #   symlink? -> true or false
+  #
+  # Returns whether the entry at the path in `self` is a symbolic link:
+  #
+  # ```ruby
+  # # Create Pathnames.
+  # file_pn = Pathname('doc/extension.rdoc') # => #<Pathname:doc/extension.rdoc>
+  # target_pn = Pathname('..').join(file_pn) # => #<Pathname:../doc/extension.rdoc>
+  # link_pn = Pathname('lib/u.tmp')          # => #<Pathname:lib/u.tmp>
+  # link_pn.symlink?                         # => false
+  # # Create link.
+  # link_pn.make_symlink(target_pn)
+  # link_pn.symlink?                         # => true
+  # link_pn.delete                           # Clean up.
+  # ```
+  #
   def symlink?() FileTest.symlink?(@path) end
 
   # See <tt>FileTest.writable?</tt>.
diff --git a/ruby.c b/ruby.c
index b9648bf155a1ad..f33b86419d589c 100644
--- a/ruby.c
+++ b/ruby.c
@@ -2227,7 +2227,7 @@ prism_script(ruby_cmdline_options_t *opt, pm_parse_result_t *result)
     const bool read_stdin = (strcmp(opt->script, "-") == 0);
 
     if (read_stdin) {
-        pm_options_encoding_set(options, rb_enc_name(rb_locale_encoding()));
+        pm_options_encoding_set(options, rb_enc_name(IF_UTF8_PATH(rb_utf8_encoding(), rb_locale_encoding())));
     }
     if (opt->src.enc.name != 0) {
         pm_options_encoding_set(options, StringValueCStr(opt->src.enc.name));
@@ -2844,7 +2844,7 @@ load_file_internal(VALUE argp_v)
         enc = rb_enc_from_index(opt->src.enc.index);
     }
     else if (f == rb_stdin) {
-        enc = rb_locale_encoding();
+        enc = IF_UTF8_PATH(rb_utf8_encoding(), rb_locale_encoding());
     }
     else {
         enc = rb_utf8_encoding();
diff --git a/spec/ruby/core/kernel/require_spec.rb b/spec/ruby/core/kernel/require_spec.rb
index 62d954c2bf7eee..28d94b0515121a 100644
--- a/spec/ruby/core/kernel/require_spec.rb
+++ b/spec/ruby/core/kernel/require_spec.rb
@@ -34,7 +34,7 @@
       features -= %w[java.rb jruby/util.rb]
     when "ruby"
       so = RbConfig::CONFIG['DLEXT']
-      features -= ["windows_1252.#{so}", "windows_31.#{so}"]
+      features.reject! { |feature| feature.end_with?("windows_1252.#{so}", "windows_31j.#{so}") }
       features.reject! { |feature| feature.end_with? "encdb.#{so}" }
       features.reject! { |feature| feature.end_with? "transdb.#{so}" }
       features.reject! { |feature| feature.include?('-fake') }