From 780425a6e23b57505841fa818f370f38105d56b4 Mon Sep 17 00:00:00 2001
From: lmdnipo <18809296239@163.com>
Date: Fri, 18 Sep 2026 13:40:36 +0800
Subject: [PATCH] fix(uri-template): encode literal URI characters

---
 src/mcp/shared/uri_template.py    |  3 ++-
 tests/shared/test_uri_template.py | 10 ++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/mcp/shared/uri_template.py b/src/mcp/shared/uri_template.py
index 20d6fa9c2e..847b415f9e 100644
--- a/src/mcp/shared/uri_template.py
+++ b/src/mcp/shared/uri_template.py
@@ -451,7 +451,7 @@ def expand(self, variables: Mapping[str, str | Sequence[str]]) -> str:
         out: list[str] = []
         for part in self._parts:
             if isinstance(part, str):
-                out.append(part)
+                out.append(_encode(part, allow_reserved=True))
             else:
                 out.append(_expand_expression(part, variables))
         return "".join(out)
@@ -892,6 +892,7 @@ def _flatten(parts: list[_Part]) -> list[_Atom]:
     def push_lit(text: str) -> None:
         if not text:
             return
+        text = _encode(text, allow_reserved=True)
         if atoms and isinstance(atoms[-1], _Lit):
             atoms[-1] = _Lit(atoms[-1].text + text)
         else:
diff --git a/tests/shared/test_uri_template.py b/tests/shared/test_uri_template.py
index cddbb82b0b..b2036f8652 100644
--- a/tests/shared/test_uri_template.py
+++ b/tests/shared/test_uri_template.py
@@ -479,6 +479,11 @@ def test_expand_encodes_special_chars_in_simple():
     assert t.expand({"v": "a&b=c"}) == "a%26b%3Dc"
 
 
+def test_expand_encodes_non_ascii_literal():
+    t = UriTemplate.parse("file:///docs/café/{name}")
+    assert t.expand({"name": "a.txt"}) == "file:///docs/caf%C3%A9/a.txt"
+
+
 def test_expand_preserves_special_chars_in_reserved():
     t = UriTemplate.parse("{+v}")
     assert t.expand({"v": "a&b=c"}) == "a&b=c"
@@ -764,6 +769,11 @@ def test_match_decodes_percent_encoding():
     assert t.match("file://docs/hello%20world.txt") == {"name": "hello world.txt"}
 
 
+def test_match_encodes_non_ascii_literal():
+    t = UriTemplate.parse("file:///docs/café/{name}")
+    assert t.match("file:///docs/caf%C3%A9/a.txt") == {"name": "a.txt"}
+
+
 def test_match_escapes_template_literals():
     # Regression: previous impl didn't escape . in literals, making it
     # a regex wildcard. "fileXtxt" should NOT match "file.txt/{id}".