Don't physically copy static files for mkdocs serve

Just read them from their original location in the live server instead

mkdocs/commands/build.py

@@ -246,7 +246,7 @@ def _build_page(
         config._current_page = None
 
 
-def build(config: MkDocsConfig, *, serve_url: str | None = None, dirty: bool = False) -> None:
+def build(config: MkDocsConfig, *, serve_url: str | None = None, dirty: bool = False) -> Files:
     """Perform a full site build."""
     logger = logging.getLogger('mkdocs')
 
@@ -322,7 +322,12 @@ def build(config: MkDocsConfig, *, serve_url: str | None = None, dirty: bool = F
         # with lower precedence get written first so that files with higher precedence can overwrite them.
 
         log.debug("Copying static assets.")
-        files.copy_static_files(dirty=dirty, inclusion=inclusion)
+        for file in files:
+            if not file.is_documentation_page() and inclusion(file.inclusion):
+                if serve_url and file.is_copyless_static_file:
+                    log.debug(f"Skip copying static file: '{file.src_uri}'")
+                    continue
+                file.copy_file(dirty)
 
         for template in config.theme.static_templates:
             _build_theme_template(template, env, files, config, nav)
@@ -351,6 +356,7 @@ def build(config: MkDocsConfig, *, serve_url: str | None = None, dirty: bool = F
             raise Abort(f'Aborted with {msg} in strict mode!')
 
         log.info(f'Documentation built in {time.monotonic() - start:.2f} seconds')
+        return files
 
     except Exception as e:
         # Run `build_error` plugin events.

mkdocs/commands/serve.py

@@ -1,15 +1,16 @@
 from __future__ import annotations
 
 import logging
+import os.path
 import shutil
 import tempfile
-from os.path import isdir, isfile, join
 from typing import TYPE_CHECKING
 from urllib.parse import urlsplit
 
 from mkdocs.commands.build import build
 from mkdocs.config import load_config
 from mkdocs.livereload import LiveReloadServer, _serve_url
+from mkdocs.structure.files import Files
 
 if TYPE_CHECKING:
     from mkdocs.config.defaults import MkDocsConfig
@@ -35,8 +36,6 @@ def serve(
     whenever a file is edited.
     """
     # Create a temporary build directory, and set some options to serve it
-    # PY2 returns a byte string by default. The Unicode prefix ensures a Unicode
-    # string is returned. And it makes MkDocs temp dirs easier to identify.
     site_dir = tempfile.mkdtemp(prefix='mkdocs_')
 
     def get_config():
@@ -58,22 +57,42 @@ def serve(
     mount_path = urlsplit(config.site_url or '/').path
     config.site_url = serve_url = _serve_url(host, port, mount_path)
 
+    files: Files = Files(())
+
     def builder(config: MkDocsConfig | None = None):
         log.info("Building documentation...")
         if config is None:
             config = get_config()
             config.site_url = serve_url
 
-        build(config, serve_url=None if is_clean else serve_url, dirty=is_dirty)
+        nonlocal files
+        files = build(config, serve_url=None if is_clean else serve_url, dirty=is_dirty)
+
+    def file_hook(path: str) -> str | None:
+        f = files.get_file_from_path(path)
+        if f is not None and f.is_copyless_static_file:
+            return f.abs_src_path
+        return None
+
+    def get_file(path: str) -> str | None:
+        if new_path := file_hook(path):
+            return os.path.join(site_dir, new_path)
+        if os.path.isfile(try_path := os.path.join(site_dir, path)):
+            return try_path
+        return None
 
     server = LiveReloadServer(
-        builder=builder, host=host, port=port, root=site_dir, mount_path=mount_path
+        builder=builder,
+        host=host,
+        port=port,
+        root=site_dir,
+        file_hook=file_hook,
+        mount_path=mount_path,
     )
 
     def error_handler(code) -> bytes | None:
         if code in (404, 500):
-            error_page = join(site_dir, f'{code}.html')
+            if error_page := get_file(f'{code}.html'):
-            if isfile(error_page):
                 with open(error_page, 'rb') as f:
                     return f.read()
         return None
@@ -108,5 +127,5 @@ def serve(
             server.shutdown()
     finally:
         config.plugins.on_shutdown()
-        if isdir(site_dir):
+        if os.path.isdir(site_dir):
             shutil.rmtree(site_dir)

mkdocs/livereload/__init__.py

@@ -101,6 +101,8 @@ class LiveReloadServer(socketserver.ThreadingMixIn, wsgiref.simple_server.WSGISe
         host: str,
         port: int,
         root: str,
+        *,
+        file_hook: Callable[[str], str | None] = lambda path: None,
         mount_path: str = "/",
         polling_interval: float = 0.5,
         shutdown_delay: float = 0.25,
@@ -112,6 +114,7 @@ class LiveReloadServer(socketserver.ThreadingMixIn, wsgiref.simple_server.WSGISe
         except Exception:
             pass
         self.root = os.path.abspath(root)
+        self.file_hook = file_hook
         self.mount_path = _normalize_mount_path(mount_path)
         self.url = _serve_url(host, port, mount_path)
         self.build_delay = 0.1
@@ -289,7 +292,6 @@ class LiveReloadServer(socketserver.ThreadingMixIn, wsgiref.simple_server.WSGISe
                 rel_file_path += "index.html"
             # Prevent directory traversal - normalize the path.
             rel_file_path = posixpath.normpath("/" + rel_file_path).lstrip("/")
-            file_path = os.path.join(self.root, rel_file_path)
         elif path == "/":
             start_response("302 Found", [("Location", urllib.parse.quote(self.mount_path))])
             return []
@@ -298,13 +300,20 @@ class LiveReloadServer(socketserver.ThreadingMixIn, wsgiref.simple_server.WSGISe
 
         # Wait until the ongoing rebuild (if any) finishes, so we're not serving a half-built site.
         with self._epoch_cond:
-            self._epoch_cond.wait_for(lambda: self._visible_epoch == self._wanted_epoch)
+            file_path = self.file_hook(rel_file_path)
+            if file_path is None:
+                file_path = os.path.join(self.root, rel_file_path)
+
+                self._epoch_cond.wait_for(lambda: self._visible_epoch == self._wanted_epoch)
             epoch = self._visible_epoch
 
         try:
             file: BinaryIO = open(file_path, "rb")
         except OSError:
-            if not path.endswith("/") and os.path.isfile(os.path.join(file_path, "index.html")):
+            if not path.endswith("/") and (
+                self.file_hook(rel_file_path) is not None
+                or os.path.isfile(os.path.join(file_path, "index.html"))
+            ):
                 start_response("302 Found", [("Location", urllib.parse.quote(path) + "/")])
                 return []
             return None  # Not found

mkdocs/structure/files.py

@@ -116,7 +116,7 @@ class Files:
         *,
         inclusion: Callable[[InclusionLevel], bool] = InclusionLevel.is_included,
     ) -> None:
-        """Copy static files from source to destination."""
+        """Soft-deprecated, do not use."""
         for file in self:
             if not file.is_documentation_page() and inclusion(file.inclusion):
                 file.copy_file(dirty)
@@ -464,6 +464,10 @@ class File:
         self._content = value
         self.abs_src_path = None
 
+    @utils.weak_property
+    def is_copyless_static_file(self) -> bool:
+        return self.abs_src_path is not None and self.dest_uri == self.src_uri
+
     def copy_file(self, dirty: bool = False) -> None:
         """Copy source file to destination, ensuring parent directories exist."""
         if dirty and not self.is_modified():