From 35720710f2aa70447a3e7959d69d542cc7365d00 Mon Sep 17 00:00:00 2001
From: Bennet Bo Fenner <bennet@zed.dev>
Date: Thu, 5 Mar 2026 14:48:44 +0100
Subject: [PATCH] agent: Add debug logging to `StreamingEditFileTool` (#50826)

Add some debug logging to the streaming edit file tool, to make it
easier to debug errors.

Can be enabled with
```
"log": {
  "agent": "debug",
}
```

Release Notes:

- N/A
---
 .../src/tools/streaming_edit_file_tool.rs     | 28 +++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/crates/agent/src/tools/streaming_edit_file_tool.rs b/crates/agent/src/tools/streaming_edit_file_tool.rs
index 804c4be018db59e0e9b712acf1b6b2fc088c4dd3..81846ec282a52cc694a0f1c8e8418b5202d7e0d6 100644
--- a/crates/agent/src/tools/streaming_edit_file_tool.rs
+++ b/crates/agent/src/tools/streaming_edit_file_tool.rs
@@ -567,6 +567,17 @@ impl EditSession {
                 })?;
                 let events = self.parser.finalize_edits(&edits);
                 self.process_events(&events, tool, event_stream, cx)?;
+
+                if log::log_enabled!(log::Level::Debug) {
+                    log::debug!("Got edits:");
+                    for edit in &edits {
+                        log::debug!(
+                            "  old_text: '{}', new_text: '{}'",
+                            edit.old_text.replace('\n', "\\n"),
+                            edit.new_text.replace('\n', "\\n")
+                        );
+                    }
+                }
             }
         }
 
@@ -699,6 +710,7 @@ impl EditSession {
                 ToolEditEvent::OldTextChunk {
                     chunk, done: false, ..
                 } => {
+                    log::debug!("old_text_chunk: done=false, chunk='{}'", chunk);
                     self.pipeline.ensure_resolving_old_text(&self.buffer, cx);
 
                     if let Some(EditPipelineEntry::ResolvingOldText { matcher }) =
@@ -725,6 +737,8 @@ impl EditSession {
                     chunk,
                     done: true,
                 } => {
+                    log::debug!("old_text_chunk: done=true, chunk='{}'", chunk);
+
                     self.pipeline.ensure_resolving_old_text(&self.buffer, cx);
 
                     let Some(EditPipelineEntry::ResolvingOldText { matcher }) =
@@ -767,6 +781,14 @@ impl EditSession {
                     let old_text_in_buffer =
                         snapshot.text_for_range(range.clone()).collect::<String>();
 
+                    log::debug!(
+                        "edit[{}] old_text matched at {}..{}: {:?}",
+                        edit_index,
+                        range.start,
+                        range.end,
+                        old_text_in_buffer,
+                    );
+
                     let text_snapshot = self
                         .buffer
                         .read_with(cx, |buffer, _cx| buffer.text_snapshot());
@@ -786,6 +808,8 @@ impl EditSession {
                 ToolEditEvent::NewTextChunk {
                     chunk, done: false, ..
                 } => {
+                    log::debug!("new_text_chunk: done=false, chunk='{}'", chunk);
+
                     let Some(EditPipelineEntry::StreamingNewText {
                         streaming_diff,
                         edit_cursor,
@@ -821,6 +845,8 @@ impl EditSession {
                 ToolEditEvent::NewTextChunk {
                     chunk, done: true, ..
                 } => {
+                    log::debug!("new_text_chunk: done=true, chunk='{}'", chunk);
+
                     let Some(EditPipelineEntry::StreamingNewText {
                         mut streaming_diff,
                         mut edit_cursor,
@@ -835,6 +861,8 @@ impl EditSession {
                     let mut final_text = reindenter.push(chunk);
                     final_text.push_str(&reindenter.finish());
 
+                    log::debug!("new_text_chunk: done=true, final_text='{}'", final_text);
+
                     if !final_text.is_empty() {
                         let char_ops = streaming_diff.push_new(&final_text);
                         apply_char_operations(