Add streaming_diff crate (#23264)

This PR extracts the streaming diff implementation to its own
`streaming_diff` crate.

It was duplicated between `assistant` and `assistant2`, but their
implementations were exactly the same (and I don't see a reason why they
would need to diverge).

Release Notes:

- N/A

Cargo.toml

@@ -116,6 +116,7 @@ members = [
     "crates/sqlez_macros",
     "crates/story",
     "crates/storybook",
+    "crates/streaming_diff",
     "crates/sum_tree",
     "crates/supermaven",
     "crates/supermaven_api",
@@ -307,6 +308,7 @@ sqlez = { path = "crates/sqlez" }
 sqlez_macros = { path = "crates/sqlez_macros" }
 story = { path = "crates/story" }
 storybook = { path = "crates/storybook" }
+streaming_diff = { path = "crates/streaming_diff" }
 sum_tree = { path = "crates/sum_tree" }
 supermaven = { path = "crates/supermaven" }
 supermaven_api = { path = "crates/supermaven_api" }

crates/assistant/Cargo.toml

@@ -51,7 +51,6 @@ lsp.workspace = true
 menu.workspace = true
 multi_buffer.workspace = true
 open_ai = { workspace = true, features = ["schemars"] }
-ordered-float.workspace = true
 parking_lot.workspace = true
 paths.workspace = true
 picker.workspace = true
@@ -71,6 +70,7 @@ settings.workspace = true
 similar.workspace = true
 smallvec.workspace = true
 smol.workspace = true
+streaming_diff.workspace = true
 strum.workspace = true
 telemetry.workspace = true
 telemetry_events.workspace = true

crates/assistant/src/assistant.rs

@@ -9,7 +9,6 @@ mod prompt_library;
 mod slash_command;
 pub(crate) mod slash_command_picker;
 pub mod slash_command_settings;
-mod streaming_diff;
 mod terminal_inline_assistant;
 
 use std::path::PathBuf;
@@ -39,7 +38,6 @@ pub use crate::context_store::*;
 pub(crate) use crate::inline_assistant::*;
 pub use crate::patch::*;
 use crate::slash_command_settings::SlashCommandSettings;
-pub(crate) use crate::streaming_diff::*;
 
 actions!(
     assistant,

crates/assistant/src/inline_assistant.rs

@@ -1,7 +1,6 @@
 use crate::{
-    humanize_token_count, AssistantPanel, AssistantPanelEvent, CharOperation,
-    CycleNextInlineAssist, CyclePreviousInlineAssist, LineDiff, LineOperation, RequestType,
-    StreamingDiff,
+    humanize_token_count, AssistantPanel, AssistantPanelEvent, CycleNextInlineAssist,
+    CyclePreviousInlineAssist, RequestType,
 };
 use anyhow::{anyhow, Context as _, Result};
 use assistant_settings::AssistantSettings;
@@ -56,6 +55,7 @@ use std::{
     task::{self, Poll},
     time::{Duration, Instant},
 };
+use streaming_diff::{CharOperation, LineDiff, LineOperation, StreamingDiff};
 use telemetry_events::{AssistantEvent, AssistantKind, AssistantPhase};
 use terminal_view::terminal_panel::TerminalPanel;
 use text::{OffsetRangeExt, ToPoint as _};

crates/assistant2/Cargo.toml

@@ -43,7 +43,6 @@ lsp.workspace = true
 markdown.workspace = true
 menu.workspace = true
 multi_buffer.workspace = true
-ordered-float.workspace = true
 parking_lot.workspace = true
 picker.workspace = true
 project.workspace = true
@@ -55,6 +54,7 @@ serde_json.workspace = true
 settings.workspace = true
 similar.workspace = true
 smol.workspace = true
+streaming_diff.workspace = true
 telemetry_events.workspace = true
 terminal.workspace = true
 terminal_view.workspace = true

crates/assistant2/src/assistant.rs

@@ -9,7 +9,6 @@ mod context_strip;
 mod inline_assistant;
 mod inline_prompt_editor;
 mod message_editor;
-mod streaming_diff;
 mod terminal_codegen;
 mod terminal_inline_assistant;
 mod thread;

crates/assistant2/src/buffer_codegen.rs

@@ -1,7 +1,6 @@
 use crate::context::attach_context_to_message;
 use crate::context_store::ContextStore;
 use crate::inline_prompt_editor::CodegenStatus;
-use crate::streaming_diff::{CharOperation, LineDiff, LineOperation, StreamingDiff};
 use anyhow::{Context as _, Result};
 use client::telemetry::Telemetry;
 use collections::HashSet;
@@ -29,6 +28,7 @@ use std::{
     task::{self, Poll},
     time::Instant,
 };
+use streaming_diff::{CharOperation, LineDiff, LineOperation, StreamingDiff};
 use telemetry_events::{AssistantEvent, AssistantKind, AssistantPhase};
 
 pub struct BufferCodegen {