add visual diff display

Author: alexylon

.sofosrc

@@ -55,6 +55,7 @@ src/
 │   ├── types.rs           # Tool definitions for API
 │   └── mod.rs
 ├── conversation.rs         # Message history management
+├── diff.rs                 # Contextual diff generation and display
 ├── history.rs              # Session persistence + custom instructions
 ├── repl.rs                 # Main REPL loop and display logic
 ├── syntax.rs               # Markdown/code syntax highlighting
@@ -71,6 +72,13 @@ src/
 - Handles serialization/deserialization for Anthropic API
 - Supports both regular and server-side tools (like web_search)
 
+**src/diff.rs**
+- Generate contextual diffs showing only changed code blocks
+- Uses `similar` crate for accurate line-by-line diffing
+- Formats output with colored backgrounds (red for deletions, blue for additions)
+- Context lines (default: 2) show unchanged code around changes
+- Used by morph_edit_file tool to display what changed
+
 **src/history.rs**
 - SessionMetadata: Preview and timestamps for session list
 - Session: Dual storage (api_messages + display_messages)
@@ -231,6 +239,7 @@ When waiting for Claude's response after tool execution:
 - `colored`: Terminal colors and formatting
 - `rustyline`: REPL with readline support
 - `clap`: Command-line argument parsing
+- `similar`: Text diffing for visual change display
 
 ### Optional Dependencies
 - `ripgrep`: Code search functionality (runtime check)

Cargo.lock

@@ -23,6 +23,7 @@ thiserror = "2.0"
 rustyline = "17.0"
 colored = "3.0"
 syntect = "5.2"
+similar = "2.7"
 
 # Utilities
 futures = "0.3"

Cargo.toml

@@ -16,6 +16,7 @@ A blazingly fast, interactive AI coding assistant powered by Claude, implemented
 - **Code Search** - Fast regex-based code search using `ripgrep` (optional)
 - **Web Search** - Real-time web information via Claude's native search tool
 - **Bash Execution** - Run tests and build commands safely (read-only, sandboxed)
+- **Visual diff display** - See exactly what changed with colored diffs (red for deletions, blue for additions)
 - **Secure** - All operations restricted to workspace, prevents directory traversal
 
 ## Benchmark
@@ -26,7 +27,7 @@ A blazingly fast, interactive AI coding assistant powered by Claude, implemented
 - **Sofos Code:** 1m 40s ⚡
 - **Claude Code CLI:** 4m 35s
 
-**~2.8x faster** (both with Morph Apply and `ripgrep` enabled).
+**~2.8x faster** (both tests with Morph Apply and `ripgrep` enabled).
 
 ## Installation
 

README.md

@@ -0,0 +1,43 @@
+# Morph Edit with Visual Diff Example
+
+When using `morph_edit_file`, Sofos now displays a contextual diff showing exactly what changed.
+
+## Example Output
+
+```
+Using tool: morph_edit_file
+
+Successfully applied Morph edit to 'example.js'
+
+Changes:
+  function example() {
+- var x = 1;
++ const x = 1;
+- var y = 2;
++ let y = 2;
+- var z = 3;
++ const z = 3;
+      
+    console.log(x + y + z);
+```
+
+## Features
+
+- **Contextual Display**: Shows only changed blocks with 2 lines of surrounding context
+- **Color Coding**: 
+  - Lines starting with `-` have RED background with BLACK text (deletions)
+  - Lines starting with `+` have BLUE background with BLACK text (additions)
+  - Context lines show with normal formatting (starting with two spaces)
+- **Multiple Hunks**: If changes are separated, they're shown with `...` separator
+- **Compact**: No need to see the entire file, just what changed
+
+## Technical Details
+
+- Uses the `similar` crate for accurate line-by-line diffing
+- Default context: 2 lines before and after changes
+- Groups nearby changes into single hunks for readability
+- Automatically handles edge cases (beginning/end of file)
+
+## Comparison with Other Tools
+
+This is similar to `git diff` output but optimized for terminal viewing with colored backgrounds instead of just prefixes.

docs/DIFF_DISPLAY.md

@@ -0,0 +1,70 @@
+use colored::Colorize;
+use similar::{ChangeTag, TextDiff};
+
+/// Generate a contextual diff display showing only changed blocks
+/// Returns a formatted string with colored additions (blue +) and deletions (red -)
+pub fn generate_contextual_diff(original: &str, modified: &str, context_lines: usize) -> String {
+    let diff = TextDiff::from_lines(original, modified);
+    let mut output = Vec::new();
+
+    for (idx, group) in diff.grouped_ops(context_lines).iter().enumerate() {
+        if idx > 0 {
+            // Add separator between hunks
+            output.push("".to_string());
+            output.push("...".dimmed().to_string());
+            output.push("".to_string());
+        }
+
+        for op in group {
+            for change in diff.iter_changes(op) {
+                let s: String = match change.tag() {
+                    ChangeTag::Delete => {
+                        let line = format!("- {}", change.value().trim_end());
+                        line.on_red().black().to_string()
+                    }
+                    ChangeTag::Insert => {
+                        let line = format!("+ {}", change.value().trim_end());
+                        line.on_blue().black().to_string()
+                    }
+                    ChangeTag::Equal => {
+                        let line = format!("  {}", change.value().trim_end());
+                        line.normal().to_string()
+                    }
+                };
+
+                output.push(s);
+            }
+        }
+    }
+
+    output.join("\n")
+}
+
+/// Generate a compact diff showing only changed lines with minimal context
+pub fn generate_compact_diff(original: &str, modified: &str) -> String {
+    generate_contextual_diff(original, modified, 2)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_simple_diff() {
+        let original = "line 1\nline 2\nline 3\n";
+        let modified = "line 1\nline 2 modified\nline 3\n";
+        
+        let diff = generate_compact_diff(original, modified);
+        assert!(diff.contains("line 2"));
+    }
+
+    #[test]
+    fn test_multiple_changes() {
+        let original = "var x = 1;\nvar y = 2;\nvar z = 3;\n";
+        let modified = "const x = 1;\nconst y = 2;\nconst z = 3;\n";
+        
+        let diff = generate_compact_diff(original, modified);
+        assert!(diff.contains("-"));
+        assert!(diff.contains("+"));
+    }
+}

src/diff.rs

@@ -1,6 +1,7 @@
 mod api;
 mod cli;
 mod conversation;
+mod diff;
 mod error;
 mod history;
 mod repl;

src/main.rs

@@ -744,6 +744,10 @@ impl Repl {
                     format!("Found {} items in {}", item_count, path.bright_cyan())
                 }
             }
+            "morph_edit_file" => {
+                // For morph edits, show the full output including the diff
+                output.to_string()
+            }
             _ => {
                 // For all other tools, return the full output
                 output.to_string()

src/repl.rs

@@ -4,6 +4,7 @@ pub mod filesystem;
 pub mod types;
 
 use crate::api::MorphClient;
+use crate::diff;
 use crate::error::{Result, SofosError};
 use bashexec::BashExecutor;
 use codesearch::CodeSearchTool;
@@ -91,8 +92,21 @@ impl ToolExecutor {
                     SofosError::ToolExecution("Missing 'content' parameter".to_string())
                 })?;
 
+                // Check if file exists and read original content for diff
+                let original_content = self.fs_tool.read_file(path).ok();
+                
                 self.fs_tool.write_file(path, content)?;
-                Ok(format!("Successfully wrote to file '{}'", path))
+                
+                // If file existed before, show diff
+                if let Some(original) = original_content {
+                    let diff_output = diff::generate_compact_diff(&original, content);
+                    Ok(format!(
+                        "Successfully wrote to file '{}'\n\nChanges:\n{}",
+                        path, diff_output
+                    ))
+                } else {
+                    Ok(format!("Successfully created file '{}'", path))
+                }
             }
             "list_directory" => {
                 let path = input["path"].as_str().ok_or_else(|| {
@@ -151,7 +165,14 @@ impl ToolExecutor {
                     .await?;
 
                 self.fs_tool.write_file(path, &merged_code)?;
-                Ok(format!("Successfully applied Morph edit to '{}'", path))
+                
+                // Generate diff for display
+                let diff_output = diff::generate_compact_diff(&original_code, &merged_code);
+                
+                Ok(format!(
+                    "Successfully applied Morph edit to '{}'\n\nChanges:\n{}",
+                    path, diff_output
+                ))
             }
             "delete_file" => {
                 let path = input["path"].as_str().ok_or_else(|| {