Show progress as the agent locates which range it needs to edit (#31582)

Release Notes:

- Improved latency when the agent starts streaming edits.

---------

Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>

crates/assistant_tools/src/edit_agent/edit_parser.rs

@@ -11,7 +11,7 @@ const END_TAGS: [&str; 3] = [OLD_TEXT_END_TAG, NEW_TEXT_END_TAG, EDITS_END_TAG];
 
 #[derive(Debug)]
 pub enum EditParserEvent {
-    OldText(String),
+    OldTextChunk { chunk: String, done: bool },
     NewTextChunk { chunk: String, done: bool },
 }
 
@@ -33,7 +33,7 @@ pub struct EditParser {
 #[derive(Debug, PartialEq)]
 enum EditParserState {
     Pending,
-    WithinOldText,
+    WithinOldText { start: bool },
     AfterOldText,
     WithinNewText { start: bool },
 }
@@ -56,20 +56,23 @@ impl EditParser {
                 EditParserState::Pending => {
                     if let Some(start) = self.buffer.find("<old_text>") {
                         self.buffer.drain(..start + "<old_text>".len());
-                        self.state = EditParserState::WithinOldText;
+                        self.state = EditParserState::WithinOldText { start: true };
                     } else {
                         break;
                     }
                 }
-                EditParserState::WithinOldText => {
-                    if let Some(tag_range) = self.find_end_tag() {
-                        let mut start = 0;
-                        if self.buffer.starts_with('\n') {
-                            start = 1;
+                EditParserState::WithinOldText { start } => {
+                    if !self.buffer.is_empty() {
+                        if *start && self.buffer.starts_with('\n') {
+                            self.buffer.remove(0);
                         }
-                        let mut old_text = self.buffer[start..tag_range.start].to_string();
-                        if old_text.ends_with('\n') {
-                            old_text.pop();
+                        *start = false;
+                    }
+
+                    if let Some(tag_range) = self.find_end_tag() {
+                        let mut chunk = self.buffer[..tag_range.start].to_string();
+                        if chunk.ends_with('\n') {
+                            chunk.pop();
                         }
 
                         self.metrics.tags += 1;
@@ -79,8 +82,14 @@ impl EditParser {
 
                         self.buffer.drain(..tag_range.end);
                         self.state = EditParserState::AfterOldText;
-                        edit_events.push(EditParserEvent::OldText(old_text));
+                        edit_events.push(EditParserEvent::OldTextChunk { chunk, done: true });
                     } else {
+                        if !self.ends_with_tag_prefix() {
+                            edit_events.push(EditParserEvent::OldTextChunk {
+                                chunk: mem::take(&mut self.buffer),
+                                done: false,
+                            });
+                        }
                         break;
                     }
                 }
@@ -115,11 +124,7 @@ impl EditParser {
                         self.state = EditParserState::Pending;
                         edit_events.push(EditParserEvent::NewTextChunk { chunk, done: true });
                     } else {
-                        let mut end_prefixes = END_TAGS
-                            .iter()
-                            .flat_map(|tag| (1..tag.len()).map(move |i| &tag[..i]))
-                            .chain(["\n"]);
-                        if end_prefixes.all(|prefix| !self.buffer.ends_with(&prefix)) {
+                        if !self.ends_with_tag_prefix() {
                             edit_events.push(EditParserEvent::NewTextChunk {
                                 chunk: mem::take(&mut self.buffer),
                                 done: false,
@@ -141,6 +146,14 @@ impl EditParser {
         Some(start_ix..start_ix + tag.len())
     }
 
+    fn ends_with_tag_prefix(&self) -> bool {
+        let mut end_prefixes = END_TAGS
+            .iter()
+            .flat_map(|tag| (1..tag.len()).map(move |i| &tag[..i]))
+            .chain(["\n"]);
+        end_prefixes.any(|prefix| self.buffer.ends_with(&prefix))
+    }
+
     pub fn finish(self) -> EditParserMetrics {
         self.metrics
     }
@@ -412,20 +425,28 @@ mod tests {
         chunk_indices.sort();
         chunk_indices.push(input.len());
 
+        let mut old_text = Some(String::new());
+        let mut new_text = None;
         let mut pending_edit = Edit::default();
         let mut edits = Vec::new();
         let mut last_ix = 0;
         for chunk_ix in chunk_indices {
             for event in parser.push(&input[last_ix..chunk_ix]) {
                 match event {
-                    EditParserEvent::OldText(old_text) => {
-                        pending_edit.old_text = old_text;
+                    EditParserEvent::OldTextChunk { chunk, done } => {
+                        old_text.as_mut().unwrap().push_str(&chunk);
+                        if done {
+                            pending_edit.old_text = old_text.take().unwrap();
+                            new_text = Some(String::new());
+                        }
                     }
                     EditParserEvent::NewTextChunk { chunk, done } => {
-                        pending_edit.new_text.push_str(&chunk);
+                        new_text.as_mut().unwrap().push_str(&chunk);
                         if done {
+                            pending_edit.new_text = new_text.take().unwrap();
                             edits.push(pending_edit);
                             pending_edit = Edit::default();
+                            old_text = Some(String::new());
                         }
                     }
                 }
@@ -433,8 +454,6 @@ mod tests {
             last_ix = chunk_ix;
         }
 
-        assert_eq!(pending_edit, Edit::default(), "unfinished edit");
-
         edits
     }
 }

crates/assistant_tools/src/edit_agent/streaming_fuzzy_matcher.rs

@@ -0,0 +1,694 @@
+use language::{Point, TextBufferSnapshot};
+use std::{cmp, ops::Range};
+
+const REPLACEMENT_COST: u32 = 1;
+const INSERTION_COST: u32 = 3;
+const DELETION_COST: u32 = 10;
+
+/// A streaming fuzzy matcher that can process text chunks incrementally
+/// and return the best match found so far at each step.
+pub struct StreamingFuzzyMatcher {
+    snapshot: TextBufferSnapshot,
+    query_lines: Vec<String>,
+    incomplete_line: String,
+    best_match: Option<Range<usize>>,
+    matrix: SearchMatrix,
+}
+
+impl StreamingFuzzyMatcher {
+    pub fn new(snapshot: TextBufferSnapshot) -> Self {
+        let buffer_line_count = snapshot.max_point().row as usize + 1;
+        Self {
+            snapshot,
+            query_lines: Vec::new(),
+            incomplete_line: String::new(),
+            best_match: None,
+            matrix: SearchMatrix::new(buffer_line_count + 1),
+        }
+    }
+
+    /// Returns the query lines.
+    pub fn query_lines(&self) -> &[String] {
+        &self.query_lines
+    }
+
+    /// Push a new chunk of text and get the best match found so far.
+    ///
+    /// This method accumulates text chunks and processes complete lines.
+    /// Partial lines are buffered internally until a newline is received.
+    ///
+    /// # Returns
+    ///
+    /// Returns `Some(range)` if a match has been found with the accumulated
+    /// query so far, or `None` if no suitable match exists yet.
+    pub fn push(&mut self, chunk: &str) -> Option<Range<usize>> {
+        // Add the chunk to our incomplete line buffer
+        self.incomplete_line.push_str(chunk);
+
+        if let Some((last_pos, _)) = self.incomplete_line.match_indices('\n').next_back() {
+            let complete_part = &self.incomplete_line[..=last_pos];
+
+            // Split into lines and add to query_lines
+            for line in complete_part.lines() {
+                self.query_lines.push(line.to_string());
+            }
+
+            self.incomplete_line.replace_range(..last_pos + 1, "");
+
+            self.best_match = self.resolve_location_fuzzy();
+        }
+
+        self.best_match.clone()
+    }
+
+    /// Finish processing and return the final best match.
+    ///
+    /// This processes any remaining incomplete line before returning the final
+    /// match result.
+    pub fn finish(&mut self) -> Option<Range<usize>> {
+        // Process any remaining incomplete line
+        if !self.incomplete_line.is_empty() {
+            self.query_lines.push(self.incomplete_line.clone());
+            self.best_match = self.resolve_location_fuzzy();
+        }
+
+        self.best_match.clone()
+    }
+
+    fn resolve_location_fuzzy(&mut self) -> Option<Range<usize>> {
+        let new_query_line_count = self.query_lines.len();
+        let old_query_line_count = self.matrix.rows.saturating_sub(1);
+        if new_query_line_count == old_query_line_count {
+            return None;
+        }
+
+        self.matrix.resize_rows(new_query_line_count + 1);
+
+        // Process only the new query lines
+        for row in old_query_line_count..new_query_line_count {
+            let query_line = self.query_lines[row].trim();
+            let leading_deletion_cost = (row + 1) as u32 * DELETION_COST;
+
+            self.matrix.set(
+                row + 1,
+                0,
+                SearchState::new(leading_deletion_cost, SearchDirection::Up),
+            );
+
+            let mut buffer_lines = self.snapshot.as_rope().chunks().lines();
+            let mut col = 0;
+            while let Some(buffer_line) = buffer_lines.next() {
+                let buffer_line = buffer_line.trim();
+                let up = SearchState::new(
+                    self.matrix
+                        .get(row, col + 1)
+                        .cost
+                        .saturating_add(DELETION_COST),
+                    SearchDirection::Up,
+                );
+                let left = SearchState::new(
+                    self.matrix
+                        .get(row + 1, col)
+                        .cost
+                        .saturating_add(INSERTION_COST),
+                    SearchDirection::Left,
+                );
+                let diagonal = SearchState::new(
+                    if query_line == buffer_line {
+                        self.matrix.get(row, col).cost
+                    } else if fuzzy_eq(query_line, buffer_line) {
+                        self.matrix.get(row, col).cost + REPLACEMENT_COST
+                    } else {
+                        self.matrix
+                            .get(row, col)
+                            .cost
+                            .saturating_add(DELETION_COST + INSERTION_COST)
+                    },
+                    SearchDirection::Diagonal,
+                );
+                self.matrix
+                    .set(row + 1, col + 1, up.min(left).min(diagonal));
+                col += 1;
+            }
+        }
+
+        // Traceback to find the best match
+        let buffer_line_count = self.snapshot.max_point().row as usize + 1;
+        let mut buffer_row_end = buffer_line_count as u32;
+        let mut best_cost = u32::MAX;
+        for col in 1..=buffer_line_count {
+            let cost = self.matrix.get(new_query_line_count, col).cost;
+            if cost < best_cost {
+                best_cost = cost;
+                buffer_row_end = col as u32;
+            }
+        }
+
+        let mut matched_lines = 0;
+        let mut query_row = new_query_line_count;
+        let mut buffer_row_start = buffer_row_end;
+        while query_row > 0 && buffer_row_start > 0 {
+            let current = self.matrix.get(query_row, buffer_row_start as usize);
+            match current.direction {
+                SearchDirection::Diagonal => {
+                    query_row -= 1;
+                    buffer_row_start -= 1;
+                    matched_lines += 1;
+                }
+                SearchDirection::Up => {
+                    query_row -= 1;
+                }
+                SearchDirection::Left => {
+                    buffer_row_start -= 1;
+                }
+            }
+        }
+
+        let matched_buffer_row_count = buffer_row_end - buffer_row_start;
+        let matched_ratio = matched_lines as f32
+            / (matched_buffer_row_count as f32).max(new_query_line_count as f32);
+        if matched_ratio >= 0.8 {
+            let buffer_start_ix = self
+                .snapshot
+                .point_to_offset(Point::new(buffer_row_start, 0));
+            let buffer_end_ix = self.snapshot.point_to_offset(Point::new(
+                buffer_row_end - 1,
+                self.snapshot.line_len(buffer_row_end - 1),
+            ));
+            Some(buffer_start_ix..buffer_end_ix)
+        } else {
+            None
+        }
+    }
+}
+
+fn fuzzy_eq(left: &str, right: &str) -> bool {
+    const THRESHOLD: f64 = 0.8;
+
+    let min_levenshtein = left.len().abs_diff(right.len());
+    let min_normalized_levenshtein =
+        1. - (min_levenshtein as f64 / cmp::max(left.len(), right.len()) as f64);
+    if min_normalized_levenshtein < THRESHOLD {
+        return false;
+    }
+
+    strsim::normalized_levenshtein(left, right) >= THRESHOLD
+}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+enum SearchDirection {
+    Up,
+    Left,
+    Diagonal,
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
+struct SearchState {
+    cost: u32,
+    direction: SearchDirection,
+}
+
+impl SearchState {
+    fn new(cost: u32, direction: SearchDirection) -> Self {
+        Self { cost, direction }
+    }
+}
+
+struct SearchMatrix {
+    cols: usize,
+    rows: usize,
+    data: Vec<SearchState>,
+}
+
+impl SearchMatrix {
+    fn new(cols: usize) -> Self {
+        SearchMatrix {
+            cols,
+            rows: 0,
+            data: Vec::new(),
+        }
+    }
+
+    fn resize_rows(&mut self, needed_rows: usize) {
+        debug_assert!(needed_rows > self.rows);
+        self.rows = needed_rows;
+        self.data.resize(
+            self.rows * self.cols,
+            SearchState::new(0, SearchDirection::Diagonal),
+        );
+    }
+
+    fn get(&self, row: usize, col: usize) -> SearchState {
+        debug_assert!(row < self.rows && col < self.cols);
+        self.data[row * self.cols + col]
+    }
+
+    fn set(&mut self, row: usize, col: usize, state: SearchState) {
+        debug_assert!(row < self.rows && col < self.cols);
+        self.data[row * self.cols + col] = state;
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use indoc::indoc;
+    use language::{BufferId, TextBuffer};
+    use rand::prelude::*;
+    use util::test::{generate_marked_text, marked_text_ranges};
+
+    #[test]
+    fn test_empty_query() {
+        let buffer = TextBuffer::new(
+            0,
+            BufferId::new(1).unwrap(),
+            "Hello world\nThis is a test\nFoo bar baz",
+        );
+        let snapshot = buffer.snapshot();
+
+        let mut finder = StreamingFuzzyMatcher::new(snapshot.clone());
+        assert_eq!(push(&mut finder, ""), None);
+        assert_eq!(finish(finder), None);
+    }
+
+    #[test]
+    fn test_streaming_exact_match() {
+        let buffer = TextBuffer::new(
+            0,
+            BufferId::new(1).unwrap(),
+            "Hello world\nThis is a test\nFoo bar baz",
+        );
+        let snapshot = buffer.snapshot();
+
+        let mut finder = StreamingFuzzyMatcher::new(snapshot.clone());
+
+        // Push partial query
+        assert_eq!(push(&mut finder, "This"), None);
+
+        // Complete the line
+        assert_eq!(
+            push(&mut finder, " is a test\n"),
+            Some("This is a test".to_string())
+        );
+
+        // Finish should return the same result
+        assert_eq!(finish(finder), Some("This is a test".to_string()));
+    }
+
+    #[test]
+    fn test_streaming_fuzzy_match() {
+        let buffer = TextBuffer::new(
+            0,
+            BufferId::new(1).unwrap(),
+            indoc! {"
+                function foo(a, b) {
+                    return a + b;
+                }
+
+                function bar(x, y) {
+                    return x * y;
+                }
+            "},
+        );
+        let snapshot = buffer.snapshot();
+
+        let mut finder = StreamingFuzzyMatcher::new(snapshot.clone());
+
+        // Push a fuzzy query that should match the first function
+        assert_eq!(
+            push(&mut finder, "function foo(a, c) {\n").as_deref(),
+            Some("function foo(a, b) {")
+        );
+        assert_eq!(
+            push(&mut finder, "    return a + c;\n}\n").as_deref(),
+            Some(concat!(
+                "function foo(a, b) {\n",
+                "    return a + b;\n",
+                "}"
+            ))
+        );
+    }
+
+    #[test]
+    fn test_incremental_improvement() {
+        let buffer = TextBuffer::new(
+            0,
+            BufferId::new(1).unwrap(),
+            "Line 1\nLine 2\nLine 3\nLine 4\nLine 5",
+        );
+        let snapshot = buffer.snapshot();
+
+        let mut finder = StreamingFuzzyMatcher::new(snapshot.clone());
+
+        // No match initially
+        assert_eq!(push(&mut finder, "Lin"), None);
+
+        // Get a match when we complete a line
+        assert_eq!(push(&mut finder, "e 3\n"), Some("Line 3".to_string()));
+
+        // The match might change if we add more specific content
+        assert_eq!(
+            push(&mut finder, "Line 4\n"),
+            Some("Line 3\nLine 4".to_string())
+        );
+        assert_eq!(finish(finder), Some("Line 3\nLine 4".to_string()));
+    }
+
+    #[test]
+    fn test_incomplete_lines_buffering() {
+        let buffer = TextBuffer::new(
+            0,
+            BufferId::new(1).unwrap(),
+            indoc! {"
+                The quick brown fox
+                jumps over the lazy dog
+                Pack my box with five dozen liquor jugs
+            "},
+        );
+        let snapshot = buffer.snapshot();
+
+        let mut finder = StreamingFuzzyMatcher::new(snapshot.clone());
+
+        // Push text in small chunks across line boundaries
+        assert_eq!(push(&mut finder, "jumps "), None); // No newline yet
+        assert_eq!(push(&mut finder, "over the"), None); // Still no newline
+        assert_eq!(push(&mut finder, " lazy"), None); // Still incomplete
+
+        // Complete the line
+        assert_eq!(
+            push(&mut finder, " dog\n"),
+            Some("jumps over the lazy dog".to_string())
+        );
+    }
+
+    #[test]
+    fn test_multiline_fuzzy_match() {
+        let buffer = TextBuffer::new(
+            0,
+            BufferId::new(1).unwrap(),
+            indoc! {r#"
+                impl Display for User {
+                    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+                        write!(f, "User: {} ({})", self.name, self.email)
+                    }
+                }
+
+                impl Debug for User {
+                    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+                        f.debug_struct("User")
+                            .field("name", &self.name)
+                            .field("email", &self.email)
+                            .finish()
+                    }
+                }
+            "#},
+        );
+        let snapshot = buffer.snapshot();
+
+        let mut finder = StreamingFuzzyMatcher::new(snapshot.clone());
+
+        assert_eq!(
+            push(&mut finder, "impl Debug for User {\n"),
+            Some("impl Debug for User {".to_string())
+        );
+        assert_eq!(
+            push(
+                &mut finder,
+                "    fn fmt(&self, f: &mut Formatter) -> Result {\n"
+            )
+            .as_deref(),
+            Some(concat!(
+                "impl Debug for User {\n",
+                "    fn fmt(&self, f: &mut Formatter) -> fmt::Result {"
+            ))
+        );
+        assert_eq!(
+            push(&mut finder, "        f.debug_struct(\"User\")\n").as_deref(),
+            Some(concat!(
+                "impl Debug for User {\n",
+                "    fn fmt(&self, f: &mut Formatter) -> fmt::Result {\n",
+                "        f.debug_struct(\"User\")"
+            ))
+        );
+        assert_eq!(
+            push(
+                &mut finder,
+                "            .field(\"name\", &self.username)\n"
+            )
+            .as_deref(),
+            Some(concat!(
+                "impl Debug for User {\n",
+                "    fn fmt(&self, f: &mut Formatter) -> fmt::Result {\n",
+                "        f.debug_struct(\"User\")\n",
+                "            .field(\"name\", &self.name)"
+            ))
+        );
+        assert_eq!(
+            finish(finder).as_deref(),
+            Some(concat!(
+                "impl Debug for User {\n",
+                "    fn fmt(&self, f: &mut Formatter) -> fmt::Result {\n",
+                "        f.debug_struct(\"User\")\n",
+                "            .field(\"name\", &self.name)"
+            ))
+        );
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_resolve_location_single_line(mut rng: StdRng) {
+        assert_location_resolution(
+            concat!(
+                "    Lorem\n",
+                "«    ipsum»\n",
+                "    dolor sit amet\n",
+                "    consecteur",
+            ),
+            "ipsum",
+            &mut rng,
+        );
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_resolve_location_multiline(mut rng: StdRng) {
+        assert_location_resolution(
+            concat!(
+                "    Lorem\n",
+                "«    ipsum\n",
+                "    dolor sit amet»\n",
+                "    consecteur",
+            ),
+            "ipsum\ndolor sit amet",
+            &mut rng,
+        );
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_resolve_location_function_with_typo(mut rng: StdRng) {
+        assert_location_resolution(
+            indoc! {"
+                «fn foo1(a: usize) -> usize {
+                    40
+                }»
+
+                fn foo2(b: usize) -> usize {
+                    42
+                }
+            "},
+            "fn foo1(a: usize) -> u32 {\n40\n}",
+            &mut rng,
+        );
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_resolve_location_class_methods(mut rng: StdRng) {
+        assert_location_resolution(
+            indoc! {"
+                class Something {
+                    one() { return 1; }
+                «    two() { return 2222; }
+                    three() { return 333; }
+                    four() { return 4444; }
+                    five() { return 5555; }
+                    six() { return 6666; }»
+                    seven() { return 7; }
+                    eight() { return 8; }
+                }
+            "},
+            indoc! {"
+                two() { return 2222; }
+                four() { return 4444; }
+                five() { return 5555; }
+                six() { return 6666; }
+            "},
+            &mut rng,
+        );
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_resolve_location_imports_no_match(mut rng: StdRng) {
+        assert_location_resolution(
+            indoc! {"
+                use std::ops::Range;
+                use std::sync::Mutex;
+                use std::{
+                    collections::HashMap,
+                    env,
+                    ffi::{OsStr, OsString},
+                    fs,
+                    io::{BufRead, BufReader},
+                    mem,
+                    path::{Path, PathBuf},
+                    process::Command,
+                    sync::LazyLock,
+                    time::SystemTime,
+                };
+            "},
+            indoc! {"
+                use std::collections::{HashMap, HashSet};
+                use std::ffi::{OsStr, OsString};
+                use std::fmt::Write as _;
+                use std::fs;
+                use std::io::{BufReader, Read, Write};
+                use std::mem;
+                use std::path::{Path, PathBuf};
+                use std::process::Command;
+                use std::sync::Arc;
+            "},
+            &mut rng,
+        );
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_resolve_location_nested_closure(mut rng: StdRng) {
+        assert_location_resolution(
+            indoc! {"
+                impl Foo {
+                    fn new() -> Self {
+                        Self {
+                            subscriptions: vec![
+                                cx.observe_window_activation(window, |editor, window, cx| {
+                                    let active = window.is_window_active();
+                                    editor.blink_manager.update(cx, |blink_manager, cx| {
+                                        if active {
+                                            blink_manager.enable(cx);
+                                        } else {
+                                            blink_manager.disable(cx);
+                                        }
+                                    });
+                                }),
+                            ];
+                        }
+                    }
+                }
+            "},
+            concat!(
+                "                    editor.blink_manager.update(cx, |blink_manager, cx| {\n",
+                "                        blink_manager.enable(cx);\n",
+                "                    });",
+            ),
+            &mut rng,
+        );
+    }
+
+    #[gpui::test(iterations = 100)]
+    fn test_resolve_location_tool_invocation(mut rng: StdRng) {
+        assert_location_resolution(
+            indoc! {r#"
+                let tool = cx
+                    .update(|cx| working_set.tool(&tool_name, cx))
+                    .map_err(|err| {
+                        anyhow!("Failed to look up tool '{}': {}", tool_name, err)
+                    })?;
+
+                let Some(tool) = tool else {
+                    return Err(anyhow!("Tool '{}' not found", tool_name));
+                };
+
+                let project = project.clone();
+                let action_log = action_log.clone();
+                let messages = messages.clone();
+                let tool_result = cx
+                    .update(|cx| tool.run(invocation.input, &messages, project, action_log, cx))
+                    .map_err(|err| anyhow!("Failed to start tool '{}': {}", tool_name, err))?;
+
+                tasks.push(tool_result.output);
+            "#},
+            concat!(
+                "let tool_result = cx\n",
+                "    .update(|cx| tool.run(invocation.input, &messages, project, action_log, cx))\n",
+                "    .output;",
+            ),
+            &mut rng,
+        );
+    }
+
+    #[track_caller]
+    fn assert_location_resolution(text_with_expected_range: &str, query: &str, rng: &mut StdRng) {
+        let (text, expected_ranges) = marked_text_ranges(text_with_expected_range, false);
+        let buffer = TextBuffer::new(0, BufferId::new(1).unwrap(), text.clone());
+        let snapshot = buffer.snapshot();
+
+        let mut matcher = StreamingFuzzyMatcher::new(snapshot.clone());
+
+        // Split query into random chunks
+        let chunks = to_random_chunks(rng, query);
+
+        // Push chunks incrementally
+        for chunk in &chunks {
+            matcher.push(chunk);
+        }
+
+        let result = matcher.finish();
+
+        // If no expected ranges, we expect no match
+        if expected_ranges.is_empty() {
+            assert_eq!(
+                result, None,
+                "Expected no match for query: {:?}, but found: {:?}",
+                query, result
+            );
+        } else {
+            let mut actual_ranges = Vec::new();
+            if let Some(range) = result {
+                actual_ranges.push(range);
+            }
+
+            let text_with_actual_range = generate_marked_text(&text, &actual_ranges, false);
+            pretty_assertions::assert_eq!(
+                text_with_actual_range,
+                text_with_expected_range,
+                "Query: {:?}, Chunks: {:?}",
+                query,
+                chunks
+            );
+        }
+    }
+
+    fn to_random_chunks(rng: &mut StdRng, input: &str) -> Vec<String> {
+        let chunk_count = rng.gen_range(1..=cmp::min(input.len(), 50));
+        let mut chunk_indices = (0..input.len()).choose_multiple(rng, chunk_count);
+        chunk_indices.sort();
+        chunk_indices.push(input.len());
+
+        let mut chunks = Vec::new();
+        let mut last_ix = 0;
+        for chunk_ix in chunk_indices {
+            chunks.push(input[last_ix..chunk_ix].to_string());
+            last_ix = chunk_ix;
+        }
+        chunks
+    }
+
+    fn push(finder: &mut StreamingFuzzyMatcher, chunk: &str) -> Option<String> {
+        finder
+            .push(chunk)
+            .map(|range| finder.snapshot.text_for_range(range).collect::<String>())
+    }
+
+    fn finish(mut finder: StreamingFuzzyMatcher) -> Option<String> {
+        let snapshot = finder.snapshot.clone();
+        finder
+            .finish()
+            .map(|range| snapshot.text_for_range(range).collect::<String>())
+    }
+}