From b1fb172dde06d917cd4747efb968a1c68f2f2e46 Mon Sep 17 00:00:00 2001
From: Bryan Helmkamp <bryan@brynary.com>
Date: Thu, 26 Mar 2026 23:28:08 -0400
Subject: [PATCH] fix: detect early init failures in attach and roll back
 partial worktree state

Two pre-existing issues fixed:

1. attach: while waiting for progress.jsonl, check for terminal
   status.json and engine child death. A detached run that dies during
   early init (before any event fires) now surfaces the real failure
   instead of timing out after 10s.

2. worktree: when `git worktree add` fails after branch creation,
   roll back the branch with `git branch -D` to avoid leaking partial
   git state.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 lib/crates/fabro-cli/src/commands/attach.rs | 27 ++++++++++++++++++++-
 lib/crates/fabro-sandbox/src/worktree.rs    |  8 ++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/lib/crates/fabro-cli/src/commands/attach.rs b/lib/crates/fabro-cli/src/commands/attach.rs
index 31dfffc4d..f0745111e 100644
--- a/lib/crates/fabro-cli/src/commands/attach.rs
+++ b/lib/crates/fabro-cli/src/commands/attach.rs
@@ -56,11 +56,36 @@ pub async fn attach_run(
         });
     }
 
-    // Wait for progress.jsonl to appear
+    // Wait for progress.jsonl to appear.
+    // If the engine dies during early init (before any event is emitted),
+    // progress.jsonl may never be created. Check for terminal status or
+    // engine death so we surface the real failure instead of timing out.
     let mut wait_count = 0;
     while !progress_path.exists() {
         tokio::time::sleep(std::time::Duration::from_millis(100)).await;
         wait_count += 1;
+
+        // Check if engine died before writing any progress
+        if let Some(record) = read_status_record(&status_path) {
+            if record.status.is_terminal() {
+                progress_ui.finish();
+                return Ok(determine_exit_code(&conclusion_path, Some(record)));
+            }
+        }
+
+        if let Some(guard) = engine_guard.as_mut() {
+            if let Some(child) = guard.inner() {
+                if matches!(child.try_wait(), Ok(Some(_))) {
+                    // Engine exited without writing progress.jsonl
+                    progress_ui.finish();
+                    return Ok(determine_exit_code(
+                        &conclusion_path,
+                        read_status_record(&status_path),
+                    ));
+                }
+            }
+        }
+
         if wait_count > 100 {
             // Guard's Drop kills+waits on the engine child
             drop(engine_guard.take());
diff --git a/lib/crates/fabro-sandbox/src/worktree.rs b/lib/crates/fabro-sandbox/src/worktree.rs
index 2f53e10a7..399cac110 100644
--- a/lib/crates/fabro-sandbox/src/worktree.rs
+++ b/lib/crates/fabro-sandbox/src/worktree.rs
@@ -148,6 +148,14 @@ impl Sandbox for WorktreeSandbox {
             .exec_command(&add_cmd, 30_000, None, None, None)
             .await?;
         if result.exit_code != 0 {
+            // Roll back the branch created above so we don't leak partial state.
+            if !self.config.skip_branch_creation {
+                let rollback_cmd = format!("{GIT} branch -D {branch}");
+                let _ = self
+                    .inner
+                    .exec_command(&rollback_cmd, 30_000, None, None, None)
+                    .await;
+            }
             return Err(format!(
                 "git worktree add failed (exit {}): {}",
                 result.exit_code,