expose exp hmr and sourcemap (#5906)

* enable exp hmr and expose sourcemap

* disable by default

---------

Co-authored-by: Masen Furer <[email protected]>

Author: adhami3310

reflex/compiler/templates.py

@@ -4,7 +4,7 @@
 
 import json
 from collections.abc import Iterable, Mapping
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, Literal
 
 from reflex import constants
 from reflex.constants import Hooks
@@ -492,13 +492,21 @@ def package_json_template(
     })
 
 
-def vite_config_template(base: str, hmr: bool, force_full_reload: bool):
+def vite_config_template(
+    base: str,
+    hmr: bool,
+    force_full_reload: bool,
+    experimental_hmr: bool,
+    sourcemap: bool | Literal["inline", "hidden"],
+):
     """Template for vite.config.js.
 
     Args:
         base: The base path for the Vite config.
         hmr: Whether to enable hot module replacement.
         force_full_reload: Whether to force a full reload on changes.
+        experimental_hmr: Whether to enable experimental HMR features.
+        sourcemap: The sourcemap configuration.
 
     Returns:
         Rendered vite.config.js content as string.
@@ -550,6 +558,7 @@ def vite_config_template(base: str, hmr: bool, force_full_reload: bool):
   ].concat({"[fullReload()]" if force_full_reload else "[]"}),
   build: {{
     assetsDir: "{base}assets".slice(1),
+    sourcemap: {"true" if sourcemap is True else "false" if sourcemap is False else repr(sourcemap)},
     rollupOptions: {{
       onwarn(warning, warn) {{
         if (warning.code === "EVAL" && warning.id && warning.id.endsWith("state.js")) return;
@@ -570,6 +579,7 @@ def vite_config_template(base: str, hmr: bool, force_full_reload: bool):
   }},
   experimental: {{
     enableNativePlugin: false,
+    hmr: {"true" if experimental_hmr else "false"},
   }},
   server: {{
     port: process.env.PORT,

reflex/environment.py

@@ -17,6 +17,7 @@
     Annotated,
     Any,
     Generic,
+    Literal,
     TypeVar,
     get_args,
     get_origin,
@@ -256,6 +257,27 @@ def interpret_env_var_value(
         return interpret_existing_path_env(value, field_name)
     if field_type is Plugin:
         return interpret_plugin_env(value, field_name)
+    if get_origin(field_type) is Literal:
+        literal_values = get_args(field_type)
+        for literal_value in literal_values:
+            if isinstance(literal_value, str) and literal_value == value:
+                return literal_value
+            if isinstance(literal_value, bool):
+                try:
+                    interpreted_bool = interpret_boolean_env(value, field_name)
+                    if interpreted_bool == literal_value:
+                        return interpreted_bool
+                except EnvironmentVarValueError:
+                    continue
+            if isinstance(literal_value, int):
+                try:
+                    interpreted_int = interpret_int_env(value, field_name)
+                    if interpreted_int == literal_value:
+                        return interpreted_int
+                except EnvironmentVarValueError:
+                    continue
+        msg = f"Invalid literal value: {value!r} for {field_name}, expected one of {literal_values}"
+        raise EnvironmentVarValueError(msg)
     if get_origin(field_type) in (list, Sequence):
         return [
             interpret_env_var_value(
@@ -687,6 +709,12 @@ class EnvironmentVariables:
     # Whether to force a full reload on changes.
     VITE_FORCE_FULL_RELOAD: EnvVar[bool] = env_var(False)
 
+    # Whether to enable Rolldown's experimental HMR.
+    VITE_EXPERIMENTAL_HMR: EnvVar[bool] = env_var(False)
+
+    # Whether to generate sourcemaps for the frontend.
+    VITE_SOURCEMAP: EnvVar[Literal[False, True, "inline", "hidden"]] = env_var(False)  # noqa: RUF038
+
     # Whether to enable SSR for the frontend.
     REFLEX_SSR: EnvVar[bool] = env_var(True)
 

reflex/utils/frontend_skeleton.py

@@ -195,6 +195,8 @@ def _compile_vite_config(config: Config):
         base=base,
         hmr=environment.VITE_HMR.get(),
         force_full_reload=environment.VITE_FORCE_FULL_RELOAD.get(),
+        experimental_hmr=environment.VITE_EXPERIMENTAL_HMR.get(),
+        sourcemap=environment.VITE_SOURCEMAP.get(),
     )