From 6558245e12d19e84f645d5950f8edf17c9a19319 Mon Sep 17 00:00:00 2001
From: 4gray <serega05@gmail.com>
Date: Mon, 21 Sep 2026 02:32:59 +0200
Subject: [PATCH] fix(agents): normalize internal HTML URL whitespace

---
 docs/development/agent-workflow.md            |  3 ++-
 tools/skills/agent-guidance-markdown.mjs      |  7 +++----
 tools/skills/validate-agent-guidance.test.mjs | 11 +++++++++++
 3 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/docs/development/agent-workflow.md b/docs/development/agent-workflow.md
index 9ad64eb05..4cd10caad 100644
--- a/docs/development/agent-workflow.md
+++ b/docs/development/agent-workflow.md
@@ -57,7 +57,8 @@ Only headings present outside inert HTML containers contribute slugs or duplicat
 Explicit HTML anchors use `parse5`, excluding comments, scripts, styles and template contents.
 Rendered HTML anchor and image-map area hrefs and image sources use the same local-reference checks
 as Markdown links, including decoded attributes and fragment validation.
-URL attributes discard surrounding ASCII control/space characters before resolution.
+URL attributes remove ASCII tabs/newlines throughout and discard surrounding
+ASCII control/space characters before resolution.
 Iframe/embed sources and object data attributes are document references and retain Markdown-target anchor checks.
 Image and media references must resolve to files, not directories.
 Image references check file existence without interpreting image fragments as
diff --git a/tools/skills/agent-guidance-markdown.mjs b/tools/skills/agent-guidance-markdown.mjs
index 166c608f5..9d7460273 100644
--- a/tools/skills/agent-guidance-markdown.mjs
+++ b/tools/skills/agent-guidance-markdown.mjs
@@ -85,10 +85,9 @@ function htmlNavigation(html, inspect = () => {}) {
                 (node.tagName === 'object' && attribute.name === 'data')
             )
                 references.push({
-                    target: attribute.value.replace(
-                        /^[\u0000-\u0020]+|[\u0000-\u0020]+$/gu,
-                        ''
-                    ),
+                    target: attribute.value
+                        .replace(/[\t\n\r]/gu, '')
+                        .replace(/^[\u0000-\u0020]+|[\u0000-\u0020]+$/gu, ''),
                     image: !['a', 'area', 'iframe', 'object', 'embed'].includes(
                         node.tagName
                     ),
diff --git a/tools/skills/validate-agent-guidance.test.mjs b/tools/skills/validate-agent-guidance.test.mjs
index 909594c2a..6aac2c98a 100644
--- a/tools/skills/validate-agent-guidance.test.mjs
+++ b/tools/skills/validate-agent-guidance.test.mjs
@@ -1370,3 +1370,14 @@ for (const tag of ['object', 'embed']) {
         );
     });
 }
+
+for (const entity of ['&#9;', '&#10;', '&#13;']) {
+    test(`HTML URLs remove internal tab/newline: ${entity}`, async (t) => {
+        assert.deepEqual(
+            await diagnostics(t, {
+                'AGENTS.md': `<a href="docs/exa${entity}mple.md#repeat">Guide</a>`,
+            }),
+            []
+        );
+    });
+}