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fix(markdown): align heading slugs with GitHub anchors #197

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fix(markdown): align heading slugs with GitHub anchors #197

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1 change: 1 addition & 0 deletions Cargo.lock
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1 change: 1 addition & 0 deletions Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ log = "0.4"
pdf-inspector = "1.14.2"
quick-xml = "0.41.0"
zip = { version = "8.6.0", default-features = false, features = ["deflate"] }
unicode-properties = "0.1.4"

[profile.release]
lto = "thin"
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11 changes: 10 additions & 1 deletion src/render/markdown/anchors.rs
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Expand Up @@ -9,6 +9,7 @@

use crate::model::{Block, Document, Inline, LinkTarget, inlines_to_plain_text};
use std::collections::{HashMap, HashSet};
use unicode_properties::{GeneralCategory, UnicodeGeneralCategory};

pub(crate) struct AnchorMap {
resolved: HashMap<String, Resolved>,
Expand Down Expand Up @@ -185,7 +186,10 @@ fn gfm_slug(text: &str) -> String {
.filter_map(|c| match c {
' ' => Some('-'),
'-' => Some(c),
c if c.is_alphanumeric() || is_combining_mark(c) || is_connector_punctuation(c) => {
c if (c.is_alphanumeric() && c.general_category() != GeneralCategory::OtherNumber)

@cubic-dev-ai cubic-dev-ai Bot Oct 18, 2026 •
edited
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P3: The slug predicate now drops Other_Number characters, but the gfm_slug documentation still says that numbers are retained. Update the comment to describe the retained numeric categories so the documented contract matches the GitHub-compatible behavior.

Prompt for AI agents 
Check if this issue is valid — if so, understand the root cause and fix it. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. At src/render/markdown/anchors.rs, line 189:

<comment>The slug predicate now drops `Other_Number` characters, but the `gfm_slug` documentation still says that numbers are retained. Update the comment to describe the retained numeric categories so the documented contract matches the GitHub-compatible behavior.</comment>

<file context>
@@ -185,7 +186,10 @@ fn gfm_slug(text: &str) -> String {
             ' ' => Some('-'),
             '-' => Some(c),
-            c if c.is_alphanumeric() || is_combining_mark(c) || is_connector_punctuation(c) => {
+            c if (c.is_alphanumeric() && c.general_category() != GeneralCategory::OtherNumber)
+                || is_combining_mark(c)
+                || is_connector_punctuation(c) =>
</file context>
Fix with cubic

|| is_combining_mark(c)
|| is_connector_punctuation(c) =>
{
Some(c)
}
_ => None,
Expand All @@ -208,7 +212,9 @@ fn is_combining_mark(c: char) -> bool {
| 0x1AB0..=0x1AFF
| 0x1DC0..=0x1DFF
| 0x20D0..=0x20FF
| 0xFE00..=0xFE0F
| 0xFE20..=0xFE2F
| 0xE0100..=0xE01EF
)
}

Expand Down Expand Up @@ -253,6 +259,9 @@ mod tests {
assert_eq!(gfm_slug("combining n\u{0303} tilde"), "combining-n\u{0303}-tilde");
assert_eq!(gfm_slug("देवनागरी क्षि"), "देवनागरी-क्षि");
assert_eq!(gfm_slug("日本語の見出し"), "日本語の見出し");
assert_eq!(gfm_slug("❤️ Love"), "️-love");
assert_eq!(gfm_slug("2️⃣ Second"), "2️⃣-second");
assert_eq!(gfm_slug("x² formula ½"), "x-formula-");
}

#[test]
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