fix(markdown): preserve korean spacing in wrapped structured output

crates/forge_markdown_stream/Cargo.toml

@@ -16,8 +16,10 @@ streamdown-render = "0.1.4"
 syntect.workspace = true
 colored.workspace = true
 unicode-width = "0.2"
+unicode-segmentation = "1.12"
 terminal-colorsaurus = "1.0.3"
 
 [dev-dependencies]
 insta.workspace = true
 strip-ansi-escapes.workspace = true
+pretty_assertions.workspace = true

crates/forge_markdown_stream/src/heading.rs

@@ -1,9 +1,8 @@
 //! Heading rendering with theme-based styling.
 
-use streamdown_render::simple_wrap;
-
 use crate::inline::render_inline_content;
 use crate::style::{HeadingStyler, InlineStyler};
+use crate::utils::simple_wrap_preserving_spaces;
 
 /// Render a heading with appropriate styling.
 pub fn render_heading<S: InlineStyler + HeadingStyler>(
@@ -30,7 +29,7 @@ pub fn render_heading<S: InlineStyler + HeadingStyler>(
     // chars, etc.)
     let prefix_display_width = level as usize + 1;
     let content_width = width.saturating_sub(prefix_display_width);
-    let lines = simple_wrap(&rendered_content, content_width);
+    let lines = simple_wrap_preserving_spaces(&rendered_content, content_width);
     let mut result = Vec::new();
 
     for line in lines {
@@ -201,6 +200,29 @@ mod tests {
         ");
     }
 
+    #[test]
+    fn test_h3_wrapping_preserves_korean_word_spaces() {
+        let actual = render_with_width(3, "한글 공백 보존 확인", 12);
+
+        insta::assert_snapshot!(actual, @r"
+          <dim><h3>###</h3></dim> <h3>한글</h3>
+          <dim><h3>###</h3></dim> <h3>공백</h3>
+          <dim><h3>###</h3></dim> <h3>보존</h3>
+          <dim><h3>###</h3></dim> <h3>확인</h3>
+        ");
+    }
+
+    #[test]
+    fn test_h3_wrapping_splits_long_tokens() {
+        let actual = render_with_width(3, "supercalifragilistic", 12);
+
+        insta::assert_snapshot!(actual, @r"
+          <dim><h3>###</h3></dim> <h3>supercal</h3>
+          <dim><h3>###</h3></dim> <h3>ifragili</h3>
+          <dim><h3>###</h3></dim> <h3>stic</h3>
+        ");
+    }
+
     #[test]
     fn test_special_characters() {
         insta::assert_snapshot!(render(2, "Hello & Goodbye < World >"), @"<dim><h2>##</h2></dim> <h2>Hello & Goodbye < World ></h2>");

crates/forge_markdown_stream/src/lib.rs

@@ -12,11 +12,11 @@
 //!
 //! fn main() -> io::Result<()> {
 //!     let mut renderer = StreamdownRenderer::new(io::stdout(), 80);
-//!     
+//!
 //!     // Push tokens as they arrive from LLM
 //!     renderer.push("Hello ")?;
 //!     renderer.push("**world**!\n")?;
-//!     
+//!
 //!     // Finish rendering
 //!     let _ = renderer.finish()?;
 //!     Ok(())
@@ -109,3 +109,123 @@ impl<W: Write> StreamdownRenderer<W> {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use pretty_assertions::assert_eq;
+
+    use super::StreamdownRenderer;
+
+    fn fixture_rendered_output(markdown: &str, width: usize) -> String {
+        let mut output = Vec::new();
+        let mut fixture = StreamdownRenderer::new(&mut output, width);
+        fixture.push(markdown).unwrap();
+        fixture.finish().unwrap();
+
+        let actual = strip_ansi_escapes::strip(output);
+        String::from_utf8(actual).unwrap().trim_matches('\n').to_string()
+    }
+
+    fn fixture_rendered_output_from_chunks(chunks: &[&str], width: usize) -> String {
+        let mut output = Vec::new();
+        let mut fixture = StreamdownRenderer::new(&mut output, width);
+        for chunk in chunks {
+            fixture.push(chunk).unwrap();
+        }
+        fixture.finish().unwrap();
+
+        let actual = strip_ansi_escapes::strip(output);
+        String::from_utf8(actual).unwrap().trim_matches('\n').to_string()
+    }
+
+    #[test]
+    fn test_streaming_renderer_preserves_korean_spacing_in_structured_markdown() {
+        let fixture = concat!(
+            "## 구현 요약\n",
+            "- 각 서비스에서 metadata key를 개별 수정하지 않고, object storage 공통 레이어에서 일괄 정규화하도록 반영했습니다.\n",
+            "## 검토 사항\n",
+            "- 본 수정은 업로드 시 metadata header 이름 문제를 해결합니다.\n",
+            "- 추가적인 권한 정책, bucket policy, reverse proxy 제한이 있으면 별도 오류가 발생할 수 있습니다.\n",
+        );
+        let actual = fixture_rendered_output(fixture, 200);
+        let expected = concat!(
+            "## 구현 요약\n",
+            "• 각 서비스에서 metadata key를 개별 수정하지 않고, object storage 공통 레이어에서 일괄 정규화하도록 반영했습니다.\n",
+            "\n",
+            "## 검토 사항\n",
+            "• 본 수정은 업로드 시 metadata header 이름 문제를 해결합니다.\n",
+            "• 추가적인 권한 정책, bucket policy, reverse proxy 제한이 있으면 별도 오류가 발생할 수 있습니다.",
+        );
+
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_streaming_renderer_preserves_korean_spacing_when_structured_tail_arrives_in_chunks() {
+        let fixture = [
+            "## 검토 결과\n",
+            "- 본 사례는 스트리밍 마크다운 렌더링의 공백 재조합 문제와 관련이 있습니다.\n",
+            "- 핵심 구현은 공백 보존 래퍼에 위치합니다.\n",
+            "- 회귀 테스트는 스트리밍 렌더러 검증 항목에 추가되어 있습니다.\n\n",
+            "후속 작업은 다음과 같습니다.\n",
+            "1. 변경 사항을 검토 가능한 형식으로 정리합니다.\n",
+            "2. 실제 대화 출력과 유사한 통합 테스트 범위를 ",
+            "확장합니다.",
+        ];
+        let actual = fixture_rendered_output_from_chunks(&fixture, 200);
+        let expected = concat!(
+            "## 검토 결과\n",
+            "• 본 사례는 스트리밍 마크다운 렌더링의 공백 재조합 문제와 관련이 있습니다.\n",
+            "• 핵심 구현은 공백 보존 래퍼에 위치합니다.\n",
+            "• 회귀 테스트는 스트리밍 렌더러 검증 항목에 추가되어 있습니다.\n",
+            "\n",
+            "후속 작업은 다음과 같습니다.\n",
+            "1. 변경 사항을 검토 가능한 형식으로 정리합니다.\n",
+            "2. 실제 대화 출력과 유사한 통합 테스트 범위를 확장합니다.",
+        );
+
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_streaming_renderer_wraps_blockquotes_with_prefix_width_and_long_tokens() {
+        let fixture = "> supercalifragilistic\n> 한글 공백\n";
+        let actual = fixture_rendered_output(fixture, 10);
+        let expected = concat!(
+            "│ supercal\n",
+            "│ ifragili\n",
+            "│ stic\n",
+            "│ 한글\n",
+            "│ 공백"
+        );
+
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_streaming_renderer_wraps_blockquote_links_without_losing_separator() {
+        let fixture = "> [링크](https://example.com/very/long/path) 설명\n";
+        let actual = fixture_rendered_output(fixture, 20);
+        let expected = concat!(
+            "│ 링크\n",
+            "│ (https://example.c\n",
+            "│ om/very/long/path)\n",
+            "│ 설명"
+        );
+
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_streaming_renderer_wraps_nested_blockquotes_with_correct_prefix_width() {
+        let fixture = ">> supercalifragilistic\n";
+        let actual = fixture_rendered_output(fixture, 12);
+        let expected = concat!(
+            "│ │ supercal\n",
+            "│ │ ifragili\n",
+            "│ │ stic"
+        );
+
+        assert_eq!(actual, expected);
+    }
+}

crates/forge_markdown_stream/src/list.rs

@@ -2,10 +2,10 @@
 
 use streamdown_ansi::utils::visible_length;
 use streamdown_parser::ListBullet;
-use streamdown_render::text::text_wrap;
 
 use crate::inline::render_inline_content;
 use crate::style::{InlineStyler, ListStyler};
+use crate::utils::wrap_text_preserving_spaces;
 
 /// Bullet characters for dash lists at different nesting levels.
 const BULLETS_DASH: [&str; 4] = ["•", "◦", "▪", "‣"];
@@ -183,27 +183,25 @@ pub fn render_list_item<S: InlineStyler + ListStyler>(
     let next_prefix = format!("{}{}", margin, " ".repeat(content_indent));
 
     // Wrap the content
-    let wrapped = text_wrap(
+    let wrapped = wrap_text_preserving_spaces(
         &rendered_content,
-        width,
-        0,
+        width.saturating_sub(visible_length(&first_prefix)),
+        width.saturating_sub(visible_length(&next_prefix)),
         &first_prefix,
         &next_prefix,
-        false,
-        true,
     );
 
     if wrapped.is_empty() {
         vec![first_prefix]
     } else {
-        wrapped.lines
+        wrapped
     }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::theme::TagStyler;
+    use crate::theme::{TagStyler, Theme};
 
     fn render(indent: usize, bullet: ListBullet, content: &str) -> String {
         let mut state = ListState::default();
@@ -227,6 +225,28 @@ mod tests {
         .join("\n")
     }
 
+    fn render_visible_with_width(
+        indent: usize,
+        bullet: ListBullet,
+        content: &str,
+        width: usize,
+    ) -> String {
+        let mut state = ListState::default();
+        let actual = render_list_item(
+            indent,
+            &bullet,
+            content,
+            width,
+            "  ",
+            &Theme::default(),
+            &mut state,
+        )
+        .join("\n");
+        let stripped = strip_ansi_escapes::strip(actual.as_bytes());
+
+        String::from_utf8(stripped).unwrap()
+    }
+
     #[test]
     fn test_unordered_dash() {
         insta::assert_snapshot!(render(0, ListBullet::Dash, "Item one"), @"  <dash>•</dash> Item one");
@@ -333,11 +353,93 @@ mod tests {
             40,
         );
         insta::assert_snapshot!(result, @r"
-        <dash>•</dash> This is a very long list item that
-          should wrap to multiple lines
+        <dash>•</dash> This is a very long
+          list item that should wrap to
+          multiple lines
         ");
     }
 
+    #[test]
+    fn test_wrapping_preserves_korean_word_spaces() {
+        let actual = render_with_width(0, ListBullet::Dash, "한글 공백 보존 확인", 8);
+        let expected = "  <dash>•</dash> 한글\n    공백\n    보존\n    확인";
+
+        pretty_assertions::assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_wrapping_respects_bullet_prefix_width() {
+        let actual = render_with_width(0, ListBullet::Dash, "한글 공백", 6);
+        let expected = "  <dash>•</dash> 한\n    글\n    공\n    백";
+
+        pretty_assertions::assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_wrapping_respects_checkbox_prefix_width() {
+        let actual = render_with_width(0, ListBullet::Dash, "[ ] 한글 공백", 8);
+        let expected = "  <dash>•</dash> <unchecked></unchecked> 한\n      글\n      공\n      백";
+
+        pretty_assertions::assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_wrapping_respects_multidigit_ordered_prefix_width() {
+        let mut fixture = ListState::default();
+        for index in 1..10 {
+            let _ = render_list_item(
+                0,
+                &ListBullet::Ordered(1),
+                &format!("예시 {index}"),
+                8,
+                "  ",
+                &TagStyler,
+                &mut fixture,
+            );
+        }
+        let actual = render_list_item(
+            0,
+            &ListBullet::Ordered(1),
+            "한글 공백",
+            8,
+            "  ",
+            &TagStyler,
+            &mut fixture,
+        )
+        .join("\n");
+        let expected = "  <num>10.</num> 한\n      글\n      공\n      백";
+
+        pretty_assertions::assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_wrapping_splits_long_tokens() {
+        let actual = render_with_width(0, ListBullet::Dash, "supercalifragilistic", 10);
+        let expected = "  <dash>•</dash> superc\n    alifra\n    gilist\n    ic";
+
+        pretty_assertions::assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn test_wrapping_preserves_link_breaks() {
+        let actual = render_visible_with_width(
+            0,
+            ListBullet::Dash,
+            "[링크](https://example.com/very/long/path) 설명",
+            14,
+        );
+        let expected = concat!(
+            "  • 링크\n",
+            "    (https://e\n",
+            "    xample.com\n",
+            "    /very/long\n",
+            "    /path)\n",
+            "    설명"
+        );
+
+        pretty_assertions::assert_eq!(actual, expected);
+    }
+
     #[test]
     fn test_list_state_reset() {
         let mut state = ListState::default();