From 581fefe8dae5e94d3cbf5b5c44e20921a9ba9af0 Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Sun, 19 Jul 2026 18:29:29 +0000
Subject: [PATCH] =?UTF-8?q?=F0=9F=90=9B=20FIX:=20myst=5Frole=20backslash-g?=
 =?UTF-8?q?uard=20misparse=20at=20inline=20start?=
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The guard checking the char before the role read state.src[state.pos - 1],
which at pos 0 wraps to the last char of the inline source (negative
indexing; the IndexError branch never fires), wrongly rejecting a role at
the start of inline content whenever the content ends with a backslash.

The guard is removed entirely: \{ is already consumed by the core escape
rule before this rule runs (so the guard was dead for its intended case),
and for an escaped backslash (\\{name}`x`) it wrongly suppressed a live
role.

Closes #62
---
 CHANGELOG.md                       |  2 ++
 mdit_py_plugins/myst_role/index.py | 11 +++--------
 tests/fixtures/myst_role.md        | 21 +++++++++++++++++++++
 3 files changed, 26 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1c8165b..797ba9b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,8 @@
 
   **Requires markdown-it-py >= 4.1.0.**
 
+- 🐛 FIX: `myst_role` no longer mis-rejects a role at the start of inline content when the content ends with a backslash, and `\\{name}`x`` (an escaped backslash before a role) now parses the role (#62)
+
 ## 0.6.1 - 2026-05-13
 
 - 🐛 FIX: Nested field lists incorrectly nesting inside parent containers (#139)
diff --git a/mdit_py_plugins/myst_role/index.py b/mdit_py_plugins/myst_role/index.py
index 97a5eb9..411c360 100644
--- a/mdit_py_plugins/myst_role/index.py
+++ b/mdit_py_plugins/myst_role/index.py
@@ -21,20 +21,15 @@ def myst_role_plugin(md: MarkdownIt) -> None:
 
 
 def myst_role(state: StateInline, silent: bool) -> bool:
+    # note ``\{`` escaping is handled by the core ``escape`` rule,
+    # which runs before this rule
+
     # check name
     match = VALID_NAME_PATTERN.match(state.src[state.pos :])
     if not match:
         return False
     name = match.group(1)
 
-    # check for starting backslash escape
-    try:
-        if state.src[state.pos - 1] == "\\":
-            # escaped (this could be improved in the case of edge case '\\{')
-            return False
-    except IndexError:
-        pass
-
     # scan opening tick length
     start = pos = state.pos + match.end()
     try:
diff --git a/tests/fixtures/myst_role.md b/tests/fixtures/myst_role.md
index 4b2c248..1072d45 100644
--- a/tests/fixtures/myst_role.md
+++ b/tests/fixtures/myst_role.md
@@ -102,3 +102,24 @@ Escaped:
 .
 <p>{abc}<code>xyz</code></p>
 .
+
+Role at start with trailing backslash (#62):
+.
+{foo}`ar`\
+.
+<p><code class="myst role">{foo}[ar]</code>\</p>
+.
+
+Escaped role backslash:
+.
+\{foo}`x`
+.
+<p>{foo}<code>x</code></p>
+.
+
+Escaped double backslash before role (#62):
+.
+\\{foo}`x`
+.
+<p>\<code class="myst role">{foo}[x]</code></p>
+.