Introduce code generation (#2901)

![CleanShot 2023-08-28 at 12 24
36@2x](https://github.com/zed-industries/zed/assets/482957/f97cb399-1ac2-4fa9-94a7-137d1eec711c)


Release Notes:

- Added a new "Inline Assist" feature that lets you transform a
selection or generate new code at the cursor location by hitting
`ctrl-enter`.

Cargo.lock

@@ -102,14 +102,20 @@ dependencies = [
  "anyhow",
  "chrono",
  "collections",
+ "ctor",
  "editor",
+ "env_logger 0.9.3",
  "fs",
  "futures 0.3.28",
  "gpui",
+ "indoc",
  "isahc",
  "language",
+ "log",
  "menu",
+ "ordered-float",
  "project",
+ "rand 0.8.5",
  "regex",
  "schemars",
  "search",
@@ -5649,6 +5655,7 @@ dependencies = [
 name = "quick_action_bar"
 version = "0.1.0"
 dependencies = [
+ "ai",
  "editor",
  "gpui",
  "search",

assets/keymaps/default.json

@@ -530,7 +530,8 @@
     "bindings": {
       "alt-enter": "editor::OpenExcerpts",
       "cmd-f8": "editor::GoToHunk",
-      "cmd-shift-f8": "editor::GoToPrevHunk"
+      "cmd-shift-f8": "editor::GoToPrevHunk",
+      "ctrl-enter": "assistant::InlineAssist"
     }
   },
   {

crates/ai/Cargo.toml

@@ -24,7 +24,9 @@ workspace = { path = "../workspace" }
 anyhow.workspace = true
 chrono = { version = "0.4", features = ["serde"] }
 futures.workspace = true
+indoc.workspace = true
 isahc.workspace = true
+ordered-float.workspace = true
 regex.workspace = true
 schemars.workspace = true
 serde.workspace = true
@@ -35,3 +37,8 @@ tiktoken-rs = "0.4"
 [dev-dependencies]
 editor = { path = "../editor", features = ["test-support"] }
 project = { path = "../project", features = ["test-support"] }
+
+ctor.workspace = true
+env_logger.workspace = true
+log.workspace = true
+rand.workspace = true

crates/ai/src/ai.rs

@@ -1,28 +1,33 @@
 pub mod assistant;
 mod assistant_settings;
+mod streaming_diff;
 
-use anyhow::Result;
+use anyhow::{anyhow, Result};
 pub use assistant::AssistantPanel;
 use assistant_settings::OpenAIModel;
 use chrono::{DateTime, Local};
 use collections::HashMap;
 use fs::Fs;
-use futures::StreamExt;
+use futures::{io::BufReader, AsyncBufReadExt, AsyncReadExt, Stream, StreamExt};
-use gpui::AppContext;
+use gpui::{executor::Background, AppContext};
+use isahc::{http::StatusCode, Request, RequestExt};
 use regex::Regex;
 use serde::{Deserialize, Serialize};
 use std::{
     cmp::Reverse,
     ffi::OsStr,
     fmt::{self, Display},
+    io,
     path::PathBuf,
     sync::Arc,
 };
 use util::paths::CONVERSATIONS_DIR;
 
+const OPENAI_API_URL: &'static str = "https://api.openai.com/v1";
+
 // Data types for chat completion requests
 #[derive(Debug, Serialize)]
-struct OpenAIRequest {
+pub struct OpenAIRequest {
     model: String,
     messages: Vec<RequestMessage>,
     stream: bool,
@@ -116,7 +121,7 @@ struct RequestMessage {
 }
 
 #[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
-struct ResponseMessage {
+pub struct ResponseMessage {
     role: Option<Role>,
     content: Option<String>,
 }
@@ -150,7 +155,7 @@ impl Display for Role {
 }
 
 #[derive(Deserialize, Debug)]
-struct OpenAIResponseStreamEvent {
+pub struct OpenAIResponseStreamEvent {
     pub id: Option<String>,
     pub object: String,
     pub created: u32,
@@ -160,14 +165,14 @@ struct OpenAIResponseStreamEvent {
 }
 
 #[derive(Deserialize, Debug)]
-struct Usage {
+pub struct Usage {
     pub prompt_tokens: u32,
     pub completion_tokens: u32,
     pub total_tokens: u32,
 }
 
 #[derive(Deserialize, Debug)]
-struct ChatChoiceDelta {
+pub struct ChatChoiceDelta {
     pub index: u32,
     pub delta: ResponseMessage,
     pub finish_reason: Option<String>,
@@ -191,3 +196,97 @@ struct OpenAIChoice {
 pub fn init(cx: &mut AppContext) {
     assistant::init(cx);
 }
+
+pub async fn stream_completion(
+    api_key: String,
+    executor: Arc<Background>,
+    mut request: OpenAIRequest,
+) -> Result<impl Stream<Item = Result<OpenAIResponseStreamEvent>>> {
+    request.stream = true;
+
+    let (tx, rx) = futures::channel::mpsc::unbounded::<Result<OpenAIResponseStreamEvent>>();
+
+    let json_data = serde_json::to_string(&request)?;
+    let mut response = Request::post(format!("{OPENAI_API_URL}/chat/completions"))
+        .header("Content-Type", "application/json")
+        .header("Authorization", format!("Bearer {}", api_key))
+        .body(json_data)?
+        .send_async()
+        .await?;
+
+    let status = response.status();
+    if status == StatusCode::OK {
+        executor
+            .spawn(async move {
+                let mut lines = BufReader::new(response.body_mut()).lines();
+
+                fn parse_line(
+                    line: Result<String, io::Error>,
+                ) -> Result<Option<OpenAIResponseStreamEvent>> {
+                    if let Some(data) = line?.strip_prefix("data: ") {
+                        let event = serde_json::from_str(&data)?;
+                        Ok(Some(event))
+                    } else {
+                        Ok(None)
+                    }
+                }
+
+                while let Some(line) = lines.next().await {
+                    if let Some(event) = parse_line(line).transpose() {
+                        let done = event.as_ref().map_or(false, |event| {
+                            event
+                                .choices
+                                .last()
+                                .map_or(false, |choice| choice.finish_reason.is_some())
+                        });
+                        if tx.unbounded_send(event).is_err() {
+                            break;
+                        }
+
+                        if done {
+                            break;
+                        }
+                    }
+                }
+
+                anyhow::Ok(())
+            })
+            .detach();
+
+        Ok(rx)
+    } else {
+        let mut body = String::new();
+        response.body_mut().read_to_string(&mut body).await?;
+
+        #[derive(Deserialize)]
+        struct OpenAIResponse {
+            error: OpenAIError,
+        }
+
+        #[derive(Deserialize)]
+        struct OpenAIError {
+            message: String,
+        }
+
+        match serde_json::from_str::<OpenAIResponse>(&body) {
+            Ok(response) if !response.error.message.is_empty() => Err(anyhow!(
+                "Failed to connect to OpenAI API: {}",
+                response.error.message,
+            )),
+
+            _ => Err(anyhow!(
+                "Failed to connect to OpenAI API: {} {}",
+                response.status(),
+                body,
+            )),
+        }
+    }
+}
+
+#[cfg(test)]
+#[ctor::ctor]
+fn init_logger() {
+    if std::env::var("RUST_LOG").is_ok() {
+        env_logger::init();
+    }
+}

crates/ai/src/streaming_diff.rs

@@ -0,0 +1,293 @@
+use collections::HashMap;
+use ordered_float::OrderedFloat;
+use std::{
+    cmp,
+    fmt::{self, Debug},
+    ops::Range,
+};
+
+struct Matrix {
+    cells: Vec<f64>,
+    rows: usize,
+    cols: usize,
+}
+
+impl Matrix {
+    fn new() -> Self {
+        Self {
+            cells: Vec::new(),
+            rows: 0,
+            cols: 0,
+        }
+    }
+
+    fn resize(&mut self, rows: usize, cols: usize) {
+        self.cells.resize(rows * cols, 0.);
+        self.rows = rows;
+        self.cols = cols;
+    }
+
+    fn get(&self, row: usize, col: usize) -> f64 {
+        if row >= self.rows {
+            panic!("row out of bounds")
+        }
+
+        if col >= self.cols {
+            panic!("col out of bounds")
+        }
+        self.cells[col * self.rows + row]
+    }
+
+    fn set(&mut self, row: usize, col: usize, value: f64) {
+        if row >= self.rows {
+            panic!("row out of bounds")
+        }
+
+        if col >= self.cols {
+            panic!("col out of bounds")
+        }
+
+        self.cells[col * self.rows + row] = value;
+    }
+}
+
+impl Debug for Matrix {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        writeln!(f)?;
+        for i in 0..self.rows {
+            for j in 0..self.cols {
+                write!(f, "{:5}", self.get(i, j))?;
+            }
+            writeln!(f)?;
+        }
+        Ok(())
+    }
+}
+
+#[derive(Debug)]
+pub enum Hunk {
+    Insert { text: String },
+    Remove { len: usize },
+    Keep { len: usize },
+}
+
+pub struct StreamingDiff {
+    old: Vec<char>,
+    new: Vec<char>,
+    scores: Matrix,
+    old_text_ix: usize,
+    new_text_ix: usize,
+    equal_runs: HashMap<(usize, usize), u32>,
+}
+
+impl StreamingDiff {
+    const INSERTION_SCORE: f64 = -1.;
+    const DELETION_SCORE: f64 = -20.;
+    const EQUALITY_BASE: f64 = 1.8;
+    const MAX_EQUALITY_EXPONENT: i32 = 16;
+
+    pub fn new(old: String) -> Self {
+        let old = old.chars().collect::<Vec<_>>();
+        let mut scores = Matrix::new();
+        scores.resize(old.len() + 1, 1);
+        for i in 0..=old.len() {
+            scores.set(i, 0, i as f64 * Self::DELETION_SCORE);
+        }
+        Self {
+            old,
+            new: Vec::new(),
+            scores,
+            old_text_ix: 0,
+            new_text_ix: 0,
+            equal_runs: Default::default(),
+        }
+    }
+
+    pub fn push_new(&mut self, text: &str) -> Vec<Hunk> {
+        self.new.extend(text.chars());
+        self.scores.resize(self.old.len() + 1, self.new.len() + 1);
+
+        for j in self.new_text_ix + 1..=self.new.len() {
+            self.scores.set(0, j, j as f64 * Self::INSERTION_SCORE);
+            for i in 1..=self.old.len() {
+                let insertion_score = self.scores.get(i, j - 1) + Self::INSERTION_SCORE;
+                let deletion_score = self.scores.get(i - 1, j) + Self::DELETION_SCORE;
+                let equality_score = if self.old[i - 1] == self.new[j - 1] {
+                    let mut equal_run = self.equal_runs.get(&(i - 1, j - 1)).copied().unwrap_or(0);
+                    equal_run += 1;
+                    self.equal_runs.insert((i, j), equal_run);
+
+                    let exponent = cmp::min(equal_run as i32 / 4, Self::MAX_EQUALITY_EXPONENT);
+                    self.scores.get(i - 1, j - 1) + Self::EQUALITY_BASE.powi(exponent)
+                } else {
+                    f64::NEG_INFINITY
+                };
+
+                let score = insertion_score.max(deletion_score).max(equality_score);
+                self.scores.set(i, j, score);
+            }
+        }
+
+        let mut max_score = f64::NEG_INFINITY;
+        let mut next_old_text_ix = self.old_text_ix;
+        let next_new_text_ix = self.new.len();
+        for i in self.old_text_ix..=self.old.len() {
+            let score = self.scores.get(i, next_new_text_ix);
+            if score > max_score {
+                max_score = score;
+                next_old_text_ix = i;
+            }
+        }
+
+        let hunks = self.backtrack(next_old_text_ix, next_new_text_ix);
+        self.old_text_ix = next_old_text_ix;
+        self.new_text_ix = next_new_text_ix;
+        hunks
+    }
+
+    fn backtrack(&self, old_text_ix: usize, new_text_ix: usize) -> Vec<Hunk> {
+        let mut pending_insert: Option<Range<usize>> = None;
+        let mut hunks = Vec::new();
+        let mut i = old_text_ix;
+        let mut j = new_text_ix;
+        while (i, j) != (self.old_text_ix, self.new_text_ix) {
+            let insertion_score = if j > self.new_text_ix {
+                Some((i, j - 1))
+            } else {
+                None
+            };
+            let deletion_score = if i > self.old_text_ix {
+                Some((i - 1, j))
+            } else {
+                None
+            };
+            let equality_score = if i > self.old_text_ix && j > self.new_text_ix {
+                if self.old[i - 1] == self.new[j - 1] {
+                    Some((i - 1, j - 1))
+                } else {
+                    None
+                }
+            } else {
+                None
+            };
+
+            let (prev_i, prev_j) = [insertion_score, deletion_score, equality_score]
+                .iter()
+                .max_by_key(|cell| cell.map(|(i, j)| OrderedFloat(self.scores.get(i, j))))
+                .unwrap()
+                .unwrap();
+
+            if prev_i == i && prev_j == j - 1 {
+                if let Some(pending_insert) = pending_insert.as_mut() {
+                    pending_insert.start = prev_j;
+                } else {
+                    pending_insert = Some(prev_j..j);
+                }
+            } else {
+                if let Some(range) = pending_insert.take() {
+                    hunks.push(Hunk::Insert {
+                        text: self.new[range].iter().collect(),
+                    });
+                }
+
+                let char_len = self.old[i - 1].len_utf8();
+                if prev_i == i - 1 && prev_j == j {
+                    if let Some(Hunk::Remove { len }) = hunks.last_mut() {
+                        *len += char_len;
+                    } else {
+                        hunks.push(Hunk::Remove { len: char_len })
+                    }
+                } else {
+                    if let Some(Hunk::Keep { len }) = hunks.last_mut() {
+                        *len += char_len;
+                    } else {
+                        hunks.push(Hunk::Keep { len: char_len })
+                    }
+                }
+            }
+
+            i = prev_i;
+            j = prev_j;
+        }
+
+        if let Some(range) = pending_insert.take() {
+            hunks.push(Hunk::Insert {
+                text: self.new[range].iter().collect(),
+            });
+        }
+
+        hunks.reverse();
+        hunks
+    }
+
+    pub fn finish(self) -> Vec<Hunk> {
+        self.backtrack(self.old.len(), self.new.len())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::env;
+
+    use super::*;
+    use rand::prelude::*;
+
+    #[gpui::test(iterations = 100)]
+    fn test_random_diffs(mut rng: StdRng) {
+        let old_text_len = env::var("OLD_TEXT_LEN")
+            .map(|i| i.parse().expect("invalid `OLD_TEXT_LEN` variable"))
+            .unwrap_or(10);
+        let new_text_len = env::var("NEW_TEXT_LEN")
+            .map(|i| i.parse().expect("invalid `NEW_TEXT_LEN` variable"))
+            .unwrap_or(10);
+
+        let old = util::RandomCharIter::new(&mut rng)
+            .take(old_text_len)
+            .collect::<String>();
+        log::info!("old text: {:?}", old);
+
+        let mut diff = StreamingDiff::new(old.clone());
+        let mut hunks = Vec::new();
+        let mut new_len = 0;
+        let mut new = String::new();
+        while new_len < new_text_len {
+            let new_chunk_len = rng.gen_range(1..=new_text_len - new_len);
+            let new_chunk = util::RandomCharIter::new(&mut rng)
+                .take(new_len)
+                .collect::<String>();
+            log::info!("new chunk: {:?}", new_chunk);
+            new_len += new_chunk_len;
+            new.push_str(&new_chunk);
+            let new_hunks = diff.push_new(&new_chunk);
+            log::info!("hunks: {:?}", new_hunks);
+            hunks.extend(new_hunks);
+        }
+        let final_hunks = diff.finish();
+        log::info!("final hunks: {:?}", final_hunks);
+        hunks.extend(final_hunks);
+
+        log::info!("new text: {:?}", new);
+        let mut old_ix = 0;
+        let mut new_ix = 0;
+        let mut patched = String::new();
+        for hunk in hunks {
+            match hunk {
+                Hunk::Keep { len } => {
+                    assert_eq!(&old[old_ix..old_ix + len], &new[new_ix..new_ix + len]);
+                    patched.push_str(&old[old_ix..old_ix + len]);
+                    old_ix += len;
+                    new_ix += len;
+                }
+                Hunk::Remove { len } => {
+                    old_ix += len;
+                }
+                Hunk::Insert { text } => {
+                    assert_eq!(text, &new[new_ix..new_ix + text.len()]);
+                    patched.push_str(&text);
+                    new_ix += text.len();
+                }
+            }
+        }
+        assert_eq!(patched, new);
+    }
+}

crates/editor/src/editor.rs

@@ -1635,6 +1635,15 @@ impl Editor {
         self.read_only = read_only;
     }
 
+    pub fn set_field_editor_style(
+        &mut self,
+        style: Option<Arc<GetFieldEditorTheme>>,
+        cx: &mut ViewContext<Self>,
+    ) {
+        self.get_field_editor_theme = style;
+        cx.notify();
+    }
+
     pub fn replica_id_map(&self) -> Option<&HashMap<ReplicaId, ReplicaId>> {
         self.replica_id_mapping.as_ref()
     }
@@ -4989,6 +4998,9 @@ impl Editor {
             self.unmark_text(cx);
             self.refresh_copilot_suggestions(true, cx);
             cx.emit(Event::Edited);
+            cx.emit(Event::TransactionUndone {
+                transaction_id: tx_id,
+            });
         }
     }
 
@@ -8428,6 +8440,9 @@ pub enum Event {
         local: bool,
         autoscroll: bool,
     },
+    TransactionUndone {
+        transaction_id: TransactionId,
+    },
     Closed,
 }
 
@@ -8468,7 +8483,7 @@ impl View for Editor {
         "Editor"
     }
 
-    fn focus_in(&mut self, _: AnyViewHandle, cx: &mut ViewContext<Self>) {
+    fn focus_in(&mut self, focused: AnyViewHandle, cx: &mut ViewContext<Self>) {
         if cx.is_self_focused() {
             let focused_event = EditorFocused(cx.handle());
             cx.emit(Event::Focused);
@@ -8476,7 +8491,7 @@ impl View for Editor {
         }
         if let Some(rename) = self.pending_rename.as_ref() {
             cx.focus(&rename.editor);
-        } else {
+        } else if cx.is_self_focused() || !focused.is::<Editor>() {
             if !self.focused {
                 self.blink_manager.update(cx, BlinkManager::enable);
             }

crates/editor/src/multi_buffer.rs

@@ -617,6 +617,42 @@ impl MultiBuffer {
         }
     }
 
+    pub fn merge_transactions(
+        &mut self,
+        transaction: TransactionId,
+        destination: TransactionId,
+        cx: &mut ModelContext<Self>,
+    ) {
+        if let Some(buffer) = self.as_singleton() {
+            buffer.update(cx, |buffer, _| {
+                buffer.merge_transactions(transaction, destination)
+            });
+        } else {
+            if let Some(transaction) = self.history.forget(transaction) {
+                if let Some(destination) = self.history.transaction_mut(destination) {
+                    for (buffer_id, buffer_transaction_id) in transaction.buffer_transactions {
+                        if let Some(destination_buffer_transaction_id) =
+                            destination.buffer_transactions.get(&buffer_id)
+                        {
+                            if let Some(state) = self.buffers.borrow().get(&buffer_id) {
+                                state.buffer.update(cx, |buffer, _| {
+                                    buffer.merge_transactions(
+                                        buffer_transaction_id,
+                                        *destination_buffer_transaction_id,
+                                    )
+                                });
+                            }
+                        } else {
+                            destination
+                                .buffer_transactions
+                                .insert(buffer_id, buffer_transaction_id);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
     pub fn finalize_last_transaction(&mut self, cx: &mut ModelContext<Self>) {
         self.history.finalize_last_transaction();
         for BufferState { buffer, .. } in self.buffers.borrow().values() {
@@ -788,6 +824,20 @@ impl MultiBuffer {
         None
     }
 
+    pub fn undo_transaction(&mut self, transaction_id: TransactionId, cx: &mut ModelContext<Self>) {
+        if let Some(buffer) = self.as_singleton() {
+            buffer.update(cx, |buffer, cx| buffer.undo_transaction(transaction_id, cx));
+        } else if let Some(transaction) = self.history.remove_from_undo(transaction_id) {
+            for (buffer_id, transaction_id) in &transaction.buffer_transactions {
+                if let Some(BufferState { buffer, .. }) = self.buffers.borrow().get(buffer_id) {
+                    buffer.update(cx, |buffer, cx| {
+                        buffer.undo_transaction(*transaction_id, cx)
+                    });
+                }
+            }
+        }
+    }
+
     pub fn stream_excerpts_with_context_lines(
         &mut self,
         buffer: ModelHandle<Buffer>,
@@ -2316,6 +2366,16 @@ impl MultiBufferSnapshot {
         }
     }
 
+    pub fn prev_non_blank_row(&self, mut row: u32) -> Option<u32> {
+        while row > 0 {
+            row -= 1;
+            if !self.is_line_blank(row) {
+                return Some(row);
+            }
+        }
+        None
+    }
+
     pub fn line_len(&self, row: u32) -> u32 {
         if let Some((_, range)) = self.buffer_line_for_row(row) {
             range.end.column - range.start.column
@@ -3347,6 +3407,35 @@ impl History {
         }
     }
 
+    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
+        if let Some(ix) = self
+            .undo_stack
+            .iter()
+            .rposition(|transaction| transaction.id == transaction_id)
+        {
+            Some(self.undo_stack.remove(ix))
+        } else if let Some(ix) = self
+            .redo_stack
+            .iter()
+            .rposition(|transaction| transaction.id == transaction_id)
+        {
+            Some(self.redo_stack.remove(ix))
+        } else {
+            None
+        }
+    }
+
+    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
+        self.undo_stack
+            .iter_mut()
+            .find(|transaction| transaction.id == transaction_id)
+            .or_else(|| {
+                self.redo_stack
+                    .iter_mut()
+                    .find(|transaction| transaction.id == transaction_id)
+            })
+    }
+
     fn pop_undo(&mut self) -> Option<&mut Transaction> {
         assert_eq!(self.transaction_depth, 0);
         if let Some(transaction) = self.undo_stack.pop() {
@@ -3367,6 +3456,16 @@ impl History {
         }
     }
 
+    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&Transaction> {
+        let ix = self
+            .undo_stack
+            .iter()
+            .rposition(|transaction| transaction.id == transaction_id)?;
+        let transaction = self.undo_stack.remove(ix);
+        self.redo_stack.push(transaction);
+        self.redo_stack.last()
+    }
+
     fn group(&mut self) -> Option<TransactionId> {
         let mut count = 0;
         let mut transactions = self.undo_stack.iter();

crates/language/src/buffer.rs

@@ -1298,6 +1298,10 @@ impl Buffer {
         self.text.forget_transaction(transaction_id);
     }
 
+    pub fn merge_transactions(&mut self, transaction: TransactionId, destination: TransactionId) {
+        self.text.merge_transactions(transaction, destination);
+    }
+
     pub fn wait_for_edits(
         &mut self,
         edit_ids: impl IntoIterator<Item = clock::Local>,
@@ -1664,6 +1668,22 @@ impl Buffer {
         }
     }
 
+    pub fn undo_transaction(
+        &mut self,
+        transaction_id: TransactionId,
+        cx: &mut ModelContext<Self>,
+    ) -> bool {
+        let was_dirty = self.is_dirty();
+        let old_version = self.version.clone();
+        if let Some(operation) = self.text.undo_transaction(transaction_id) {
+            self.send_operation(Operation::Buffer(operation), cx);
+            self.did_edit(&old_version, was_dirty, cx);
+            true
+        } else {
+            false
+        }
+    }
+
     pub fn undo_to_transaction(
         &mut self,
         transaction_id: TransactionId,

crates/quick_action_bar/Cargo.toml

@@ -9,6 +9,7 @@ path = "src/quick_action_bar.rs"
 doctest = false
 
 [dependencies]
+ai = { path = "../ai" }
 editor = { path = "../editor" }
 gpui = { path = "../gpui" }
 search = { path = "../search" }

crates/quick_action_bar/src/quick_action_bar.rs

@@ -1,25 +1,29 @@
+use ai::{assistant::InlineAssist, AssistantPanel};
 use editor::Editor;
 use gpui::{
     elements::{Empty, Flex, MouseEventHandler, ParentElement, Svg},
     platform::{CursorStyle, MouseButton},
     Action, AnyElement, Element, Entity, EventContext, Subscription, View, ViewContext, ViewHandle,
+    WeakViewHandle,
 };
 
 use search::{buffer_search, BufferSearchBar};
-use workspace::{item::ItemHandle, ToolbarItemLocation, ToolbarItemView};
+use workspace::{item::ItemHandle, ToolbarItemLocation, ToolbarItemView, Workspace};
 
 pub struct QuickActionBar {
     buffer_search_bar: ViewHandle<BufferSearchBar>,
     active_item: Option<Box<dyn ItemHandle>>,
     _inlay_hints_enabled_subscription: Option<Subscription>,
+    workspace: WeakViewHandle<Workspace>,
 }
 
 impl QuickActionBar {
-    pub fn new(buffer_search_bar: ViewHandle<BufferSearchBar>) -> Self {
+    pub fn new(buffer_search_bar: ViewHandle<BufferSearchBar>, workspace: &Workspace) -> Self {
         Self {
             buffer_search_bar,
             active_item: None,
             _inlay_hints_enabled_subscription: None,
+            workspace: workspace.weak_handle(),
         }
     }
 
@@ -88,6 +92,21 @@ impl View for QuickActionBar {
             ));
         }
 
+        bar.add_child(render_quick_action_bar_button(
+            2,
+            "icons/radix/magic-wand.svg",
+            false,
+            ("Inline Assist".into(), Some(Box::new(InlineAssist))),
+            cx,
+            move |this, cx| {
+                if let Some(workspace) = this.workspace.upgrade(cx) {
+                    workspace.update(cx, |workspace, cx| {
+                        AssistantPanel::inline_assist(workspace, &Default::default(), cx);
+                    });
+                }
+            },
+        ));
+
         bar.into_any()
     }
 }

crates/rope/src/rope.rs

@@ -384,6 +384,16 @@ impl<'a> From<&'a str> for Rope {
     }
 }
 
+impl<'a> FromIterator<&'a str> for Rope {
+    fn from_iter<T: IntoIterator<Item = &'a str>>(iter: T) -> Self {
+        let mut rope = Rope::new();
+        for chunk in iter {
+            rope.push(chunk);
+        }
+        rope
+    }
+}
+
 impl From<String> for Rope {
     fn from(text: String) -> Self {
         Rope::from(text.as_str())

crates/text/src/text.rs

@@ -22,6 +22,7 @@ use postage::{oneshot, prelude::*};
 
 pub use rope::*;
 pub use selection::*;
+use util::ResultExt;
 
 use std::{
     cmp::{self, Ordering, Reverse},
@@ -263,7 +264,19 @@ impl History {
         }
     }
 
-    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> &[HistoryEntry] {
+    fn remove_from_undo(&mut self, transaction_id: TransactionId) -> Option<&HistoryEntry> {
+        assert_eq!(self.transaction_depth, 0);
+
+        let entry_ix = self
+            .undo_stack
+            .iter()
+            .rposition(|entry| entry.transaction.id == transaction_id)?;
+        let entry = self.undo_stack.remove(entry_ix);
+        self.redo_stack.push(entry);
+        self.redo_stack.last()
+    }
+
+    fn remove_from_undo_until(&mut self, transaction_id: TransactionId) -> &[HistoryEntry] {
         assert_eq!(self.transaction_depth, 0);
 
         let redo_stack_start_len = self.redo_stack.len();
@@ -278,20 +291,43 @@ impl History {
         &self.redo_stack[redo_stack_start_len..]
     }
 
-    fn forget(&mut self, transaction_id: TransactionId) {
+    fn forget(&mut self, transaction_id: TransactionId) -> Option<Transaction> {
         assert_eq!(self.transaction_depth, 0);
         if let Some(entry_ix) = self
             .undo_stack
             .iter()
             .rposition(|entry| entry.transaction.id == transaction_id)
         {
-            self.undo_stack.remove(entry_ix);
+            Some(self.undo_stack.remove(entry_ix).transaction)
         } else if let Some(entry_ix) = self
             .redo_stack
             .iter()
             .rposition(|entry| entry.transaction.id == transaction_id)
         {
-            self.undo_stack.remove(entry_ix);
+            Some(self.redo_stack.remove(entry_ix).transaction)
+        } else {
+            None
+        }
+    }
+
+    fn transaction_mut(&mut self, transaction_id: TransactionId) -> Option<&mut Transaction> {
+        let entry = self
+            .undo_stack
+            .iter_mut()
+            .rfind(|entry| entry.transaction.id == transaction_id)
+            .or_else(|| {
+                self.redo_stack
+                    .iter_mut()
+                    .rfind(|entry| entry.transaction.id == transaction_id)
+            })?;
+        Some(&mut entry.transaction)
+    }
+
+    fn merge_transactions(&mut self, transaction: TransactionId, destination: TransactionId) {
+        if let Some(transaction) = self.forget(transaction) {
+            if let Some(destination) = self.transaction_mut(destination) {
+                destination.edit_ids.extend(transaction.edit_ids);
+            }
         }
     }
 
@@ -1183,11 +1219,20 @@ impl Buffer {
         }
     }
 
+    pub fn undo_transaction(&mut self, transaction_id: TransactionId) -> Option<Operation> {
+        let transaction = self
+            .history
+            .remove_from_undo(transaction_id)?
+            .transaction
+            .clone();
+        self.undo_or_redo(transaction).log_err()
+    }
+
     #[allow(clippy::needless_collect)]
     pub fn undo_to_transaction(&mut self, transaction_id: TransactionId) -> Vec<Operation> {
         let transactions = self
             .history
-            .remove_from_undo(transaction_id)
+            .remove_from_undo_until(transaction_id)
             .iter()
             .map(|entry| entry.transaction.clone())
             .collect::<Vec<_>>();
@@ -1202,6 +1247,10 @@ impl Buffer {
         self.history.forget(transaction_id);
     }
 
+    pub fn merge_transactions(&mut self, transaction: TransactionId, destination: TransactionId) {
+        self.history.merge_transactions(transaction, destination);
+    }
+
     pub fn redo(&mut self) -> Option<(TransactionId, Operation)> {
         if let Some(entry) = self.history.pop_redo() {
             let transaction = entry.transaction.clone();

crates/theme/src/theme.rs

@@ -1150,6 +1150,17 @@ pub struct AssistantStyle {
     pub api_key_editor: FieldEditor,
     pub api_key_prompt: ContainedText,
     pub saved_conversation: SavedConversation,
+    pub inline: InlineAssistantStyle,
+}
+
+#[derive(Clone, Deserialize, Default, JsonSchema)]
+pub struct InlineAssistantStyle {
+    #[serde(flatten)]
+    pub container: ContainerStyle,
+    pub editor: FieldEditor,
+    pub disabled_editor: FieldEditor,
+    pub pending_edit_background: Color,
+    pub include_conversation: ToggleIconButtonStyle,
 }
 
 #[derive(Clone, Deserialize, Default, JsonSchema)]

crates/zed/src/zed.rs

@@ -264,8 +264,9 @@ pub fn initialize_workspace(
                                 toolbar.add_item(breadcrumbs, cx);
                                 let buffer_search_bar = cx.add_view(BufferSearchBar::new);
                                 toolbar.add_item(buffer_search_bar.clone(), cx);
-                                let quick_action_bar =
+                                let quick_action_bar = cx.add_view(|_| {
-                                    cx.add_view(|_| QuickActionBar::new(buffer_search_bar));
+                                    QuickActionBar::new(buffer_search_bar, workspace)
+                                });
                                 toolbar.add_item(quick_action_bar, cx);
                                 let project_search_bar = cx.add_view(|_| ProjectSearchBar::new());
                                 toolbar.add_item(project_search_bar, cx);

styles/src/style_tree/assistant.ts

@@ -1,5 +1,5 @@
 import { text, border, background, foreground, TextStyle } from "./components"
-import { Interactive, interactive } from "../element"
+import { Interactive, interactive, toggleable } from "../element"
 import { tab_bar_button } from "../component/tab_bar_button"
 import { StyleSets, useTheme } from "../theme"
 
@@ -59,6 +59,85 @@ export default function assistant(): any {
             background: background(theme.highest),
             padding: { left: 12 },
         },
+        inline: {
+            background: background(theme.highest),
+            margin: { top: 3, bottom: 3 },
+            border: border(theme.lowest, "on", {
+                top: true,
+                bottom: true,
+                overlay: true,
+            }),
+            editor: {
+                text: text(theme.highest, "mono", "default", { size: "sm" }),
+                placeholder_text: text(theme.highest, "sans", "on", "disabled"),
+                selection: theme.players[0],
+            },
+            disabled_editor: {
+                text: text(theme.highest, "mono", "disabled", { size: "sm" }),
+                placeholder_text: text(theme.highest, "sans", "on", "disabled"),
+                selection: {
+                    cursor: text(theme.highest, "mono", "disabled").color,
+                    selection: theme.players[0].selection,
+                },
+            },
+            pending_edit_background: background(theme.highest, "positive"),
+            include_conversation: toggleable({
+                base: interactive({
+                    base: {
+                        icon_size: 12,
+                        color: foreground(theme.highest, "variant"),
+
+                        button_width: 12,
+                        background: background(theme.highest, "on"),
+                        corner_radius: 2,
+                        border: {
+                            width: 1., color: background(theme.highest, "on")
+                        },
+                        padding: {
+                            left: 4,
+                            right: 4,
+                            top: 4,
+                            bottom: 4,
+                        },
+                    },
+                    state: {
+                        hovered: {
+                            ...text(theme.highest, "mono", "variant", "hovered"),
+                            background: background(theme.highest, "on", "hovered"),
+                            border: {
+                                width: 1., color: background(theme.highest, "on", "hovered")
+                            },
+                        },
+                        clicked: {
+                            ...text(theme.highest, "mono", "variant", "pressed"),
+                            background: background(theme.highest, "on", "pressed"),
+                            border: {
+                                width: 1., color: background(theme.highest, "on", "pressed")
+                            },
+                        },
+                    },
+                }),
+                state: {
+                    active: {
+                        default: {
+                            icon_size: 12,
+                            button_width: 12,
+                            color: foreground(theme.highest, "variant"),
+                            background: background(theme.highest, "accent"),
+                            border: border(theme.highest, "accent"),
+                        },
+                        hovered: {
+                            background: background(theme.highest, "accent", "hovered"),
+                            border: border(theme.highest, "accent", "hovered"),
+                        },
+                        clicked: {
+                            background: background(theme.highest, "accent", "pressed"),
+                            border: border(theme.highest, "accent", "pressed"),
+                        },
+                    },
+                },
+            }),
+        },
         message_header: {
             margin: { bottom: 4, top: 4 },
             background: background(theme.highest),