diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 74200993d..a134ff801 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -315,10 +315,12 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: install rust nightly
-        uses: dtolnay/rust-toolchain@nightly
+        uses: dtolnay/rust-toolchain@master
         with:
           components: rust-src
           targets: wasm32-unknown-emscripten
+          # might be able to unpin when pydodide uses emscripten 4, see below
+          toolchain: nightly-2025-02-17
 
       - name: cache rust
         uses: Swatinem/rust-cache@v2
diff --git a/python/pydantic_core/__init__.py b/python/pydantic_core/__init__.py
index 791de9d92..98b64b86e 100644
--- a/python/pydantic_core/__init__.py
+++ b/python/pydantic_core/__init__.py
@@ -89,11 +89,16 @@ class ErrorDetails(_TypedDict):
     Values which are required to render the error message, and could hence be useful in rendering custom error messages.
     Also useful for passing custom error data forward.
     """
+    url: _NotRequired[str]
+    """
+    The documentation URL giving information about the error. No URL is available if
+    a [`PydanticCustomError`][pydantic_core.PydanticCustomError] is used.
+    """
 
 
 class InitErrorDetails(_TypedDict):
     type: str | PydanticCustomError
-    """The type of error that occurred, this should a "slug" identifier that changes rarely or never."""
+    """The type of error that occurred, this should be a "slug" identifier that changes rarely or never."""
     loc: _NotRequired[tuple[int | str, ...]]
     """Tuple of strings and ints identifying where in the schema the error occurred."""
     input: _Any