Refactor SourceInfo to use filename indices instead of strings

Changed SourceInfo to store `Option<usize>` filename indices instead of
`Option<String>` filenames, with the actual filenames stored once in
ASTContext. This eliminates redundant string cloning throughout the AST.

## Changes

- **SourceInfo**: Changed `filename` field to `filename_index: Option<usize>`
- **ASTContext**: Added `filenames: Vec<String>` to store deduplicated filenames
- **SourceLocation trait**: Added lifetime-annotated `filename()` method to resolve indices

## JSON Format

Location objects now use:
- `"filenameIndex": 0` instead of `"filename": "path/to/file"`
- Top-level `"astContext": {"filenames": [...]}` field added to store filename array

## Updated Components

- JSON reader/writer to handle new format
- QMD reader to return (Pandoc, ASTContext) tuple
- All test files and snapshot comparisons
- Test infrastructure to accumulate failures for better error reporting

All tests passing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: cscheid

crates/quarto-markdown-pandoc/src/main.rs

@@ -102,7 +102,7 @@ fn main() {
         return;
     }
 
-    let pandoc = match args.from.as_str() {
+    let (pandoc, context) = match args.from.as_str() {
         "markdown" | "qmd" => {
             let error_formatter = if args.json_errors {
                 Some(
@@ -157,7 +157,7 @@ fn main() {
 
     let mut buf = Vec::new();
     match args.to.as_str() {
-        "json" => writers::json::write(&pandoc, &mut buf),
+        "json" => writers::json::write(&pandoc, &context, &mut buf),
         "native" => writers::native::write(&pandoc, &mut buf),
         "markdown" | "qmd" => writers::qmd::write(&pandoc, &mut buf),
         _ => {

crates/quarto-markdown-pandoc/src/pandoc/location.rs

@@ -22,27 +22,31 @@ pub struct Range {
 }
 
 /// Encapsulates source location information for AST nodes
+/// The filename field now holds an index into the ASTContext.filenames vector
 #[derive(Debug, Clone, PartialEq)]
 pub struct SourceInfo {
-    pub filename: Option<String>,
+    pub filename_index: Option<usize>,
     pub range: Range,
 }
 
 impl SourceInfo {
-    pub fn new(filename: Option<String>, range: Range) -> Self {
-        SourceInfo { filename, range }
+    pub fn new(filename_index: Option<usize>, range: Range) -> Self {
+        SourceInfo {
+            filename_index,
+            range,
+        }
     }
 
     pub fn with_range(range: Range) -> Self {
         SourceInfo {
-            filename: None,
+            filename_index: None,
             range,
         }
     }
 
     pub fn combine(&self, other: &SourceInfo) -> SourceInfo {
         SourceInfo {
-            filename: self.filename.clone().or(other.filename.clone()),
+            filename_index: self.filename_index.or(other.filename_index),
             range: Range {
                 start: if self.range.start < other.range.start {
                     self.range.start.clone()
@@ -60,8 +64,14 @@ impl SourceInfo {
 }
 
 pub trait SourceLocation {
-    fn filename(&self) -> Option<String>;
+    fn filename_index(&self) -> Option<usize>;
     fn range(&self) -> Range;
+
+    /// Resolve the filename from the ASTContext using the stored index
+    fn filename<'a>(&self, context: &'a ASTContext) -> Option<&'a String> {
+        self.filename_index()
+            .and_then(|idx| context.filenames.get(idx))
+    }
 }
 
 pub fn node_location(node: &tree_sitter::Node) -> Range {
@@ -86,7 +96,13 @@ pub fn node_source_info(node: &tree_sitter::Node) -> SourceInfo {
 }
 
 pub fn node_source_info_with_context(node: &tree_sitter::Node, context: &ASTContext) -> SourceInfo {
-    SourceInfo::new(context.primary_filename().cloned(), node_location(node))
+    // If the context has at least one filename, use index 0
+    let filename_index = if context.filenames.is_empty() {
+        None
+    } else {
+        Some(0)
+    };
+    SourceInfo::new(filename_index, node_location(node))
 }
 
 pub fn empty_range() -> Range {
@@ -113,8 +129,8 @@ macro_rules! impl_source_location {
     ($($type:ty),*) => {
         $(
             impl SourceLocation for $type {
-                fn filename(&self) -> Option<String> {
-                    self.source_info.filename.clone()
+                fn filename_index(&self) -> Option<usize> {
+                    self.source_info.filename_index
                 }
 
                 fn range(&self) -> Range {

crates/quarto-markdown-pandoc/src/pandoc/meta.rs

@@ -170,7 +170,7 @@ pub fn parse_metadata_strings(meta: MetaValue, outer_metadata: &mut Meta) -> Met
                 >,
             );
             match result {
-                Ok(mut pandoc) => {
+                Ok((mut pandoc, _context)) => {
                     for (k, v) in pandoc.meta.into_iter() {
                         outer_metadata.insert(k, v);
                     }

crates/quarto-markdown-pandoc/src/pandoc/treesitter.rs

@@ -301,12 +301,12 @@ fn process_native_inline<T: Write>(
         PandocNativeIntermediate::IntermediateBaseText(text, range) => {
             if let Some(_) = whitespace_re.find(&text) {
                 Inline::Space(Space {
-                    source_info: SourceInfo::new(context.primary_filename().cloned(), range),
+                    source_info: SourceInfo::new(if context.filenames.is_empty() { None } else { Some(0) }, range),
                 })
             } else {
                 Inline::Str(Str {
                     text: apply_smart_quotes(text),
-                    source_info: SourceInfo::new(context.primary_filename().cloned(), range),
+                    source_info: SourceInfo::new(if context.filenames.is_empty() { None } else { Some(0) }, range),
                 })
             }
         }
@@ -365,12 +365,12 @@ fn process_native_inlines<T: Write>(
             PandocNativeIntermediate::IntermediateBaseText(text, range) => {
                 if let Some(_) = whitespace_re.find(&text) {
                     inlines.push(Inline::Space(Space {
-                        source_info: SourceInfo::new(context.primary_filename().cloned(), range),
+                        source_info: SourceInfo::new(if context.filenames.is_empty() { None } else { Some(0) }, range),
                     }))
                 } else {
                     inlines.push(Inline::Str(Str {
                         text,
-                        source_info: SourceInfo::new(context.primary_filename().cloned(), range),
+                        source_info: SourceInfo::new(if context.filenames.is_empty() { None } else { Some(0) }, range),
                     }))
                 }
             }