From 74471f5eadde963ccaf28443b92d5e61ecfa2d31 Mon Sep 17 00:00:00 2001
From: Aaron Wong <6979793+zzwong@users.noreply.github.com>
Date: Wed, 23 Sep 2026 16:05:03 -0400
Subject: [PATCH] fix(llmadapters): launch Claude reviewers outside the PR
 checkout (#623)

Claude Code 2.1.281 rejects a working directory with its own .claude/
unless that exact directory is trusted, so every background reviewer
failed on repositories that commit .claude/. Launching there also loaded
the PR's project settings and hooks.

Background reviewers now start from the adapter work directory, as
foreground mode already does, and reach the checkout through --add-dir.
The prompt file names the checkout path.
---
 internal/llmadapters/subprocess.go      | 21 +++++++++++++--------
 internal/llmadapters/subprocess_test.go |  8 ++++++--
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/internal/llmadapters/subprocess.go b/internal/llmadapters/subprocess.go
index 33a228b..5c3b9f3 100644
--- a/internal/llmadapters/subprocess.go
+++ b/internal/llmadapters/subprocess.go
@@ -261,7 +261,7 @@ func (a *SubprocessAdapter) startClaudeBG(ctx context.Context, req Request, resu
 		_ = cleanup()
 		return nil, err
 	}
-	if err := writeClaudeBGPromptFile(req.Prompt, scratch); err != nil {
+	if err := writeClaudeBGPromptFile(req.Prompt, scratch, req.ReviewerWorkspace); err != nil {
 		_ = cleanup()
 		return nil, err
 	}
@@ -281,16 +281,14 @@ func (a *SubprocessAdapter) startClaudeBG(ctx context.Context, req Request, resu
 	}
 
 	execArgs := append(append([]string(nil), a.commandArgsPrefix...), args...)
-	launchDir := workDir
-	if req.ReviewerWorkspace != nil {
-		launchDir = req.ReviewerWorkspace.RepoDir
-	}
+	// Never launch inside the reviewer checkout: Claude would load the PR's
+	// .claude/ project settings. The checkout is reachable through --add-dir.
 	env, err := a.processEnv(req, scratch)
 	if err != nil {
 		_ = cleanup()
 		return nil, err
 	}
-	process, err := launchProcess(ctx, a.command, execArgs, launchDir, env, a.timeout, req.LogPath, cleanup, false)
+	process, err := launchProcess(ctx, a.command, execArgs, workDir, env, a.timeout, req.LogPath, cleanup, false)
 	if err != nil {
 		return nil, err
 	}
@@ -506,7 +504,7 @@ func (a *SubprocessAdapter) startClaudeForeground(ctx context.Context, req Reque
 		_ = cleanup()
 		return nil, err
 	}
-	if err := writeClaudeBGPromptFile(req.Prompt, scratch); err != nil {
+	if err := writeClaudeBGPromptFile(req.Prompt, scratch, req.ReviewerWorkspace); err != nil {
 		_ = cleanup()
 		return nil, err
 	}
@@ -1974,15 +1972,22 @@ func claudeBGSprintedValue(value any) string {
 	return stringValue
 }
 
-func writeClaudeBGPromptFile(prompt string, scratch string) error {
+func writeClaudeBGPromptFile(prompt string, scratch string, workspace *ReviewerWorkspaceRequest) error {
 	promptPath := filepath.Join(scratch, claudeBGPromptFilename)
 	resultPath := filepath.Join(scratch, claudeBGResultFilename)
+	if workspace != nil {
+		prompt = claudeReviewerWorkspaceNote(workspace.RepoDir) + "\n\n" + prompt
+	}
 	if err := os.WriteFile(promptPath, []byte(wrapClaudeBGPrompt(prompt, resultPath)), 0o600); err != nil {
 		return fmt.Errorf("llm subprocess: writing Claude bg prompt file: %w", err)
 	}
 	return nil
 }
 
+func claudeReviewerWorkspaceNote(repoDir string) string {
+	return fmt.Sprintf("The pull request checkout is at %s. Repository-relative paths in these instructions are relative to it. Your shell does not start there: run commands with `cd %q && ...` or `git -C %q`.", repoDir, repoDir, repoDir)
+}
+
 func claudeBGPositionalPrompt(scratch string) string {
 	promptPath := filepath.Join(scratch, claudeBGPromptFilename)
 	resultPath := filepath.Join(scratch, claudeBGResultFilename)
diff --git a/internal/llmadapters/subprocess_test.go b/internal/llmadapters/subprocess_test.go
index fd0d5e1..9f789a8 100644
--- a/internal/llmadapters/subprocess_test.go
+++ b/internal/llmadapters/subprocess_test.go
@@ -261,8 +261,12 @@ func TestSubprocessClaudeReviewerWorkspaceLaunch(t *testing.T) {
 	if !containsSamePath(addDirs, record.AddDir) || !containsSamePath(addDirs, repoRoot) {
 		t.Fatalf("--add-dir values = %#v, want scratch %q and repo %q", addDirs, record.AddDir, repoRoot)
 	}
-	if !samePath(t, record.Cwd, repoRoot) {
-		t.Fatalf("cwd = %q, want reviewer workspace repo %q", record.Cwd, repoRoot)
+	// Launching inside the PR checkout would load its .claude/ project settings.
+	if wantWorkDir := filepath.Join(filepath.Dir(recordPath), "claude-bg-workdir"); !samePath(t, record.Cwd, wantWorkDir) {
+		t.Fatalf("cwd = %q, want Claude bg workdir %q outside the reviewer checkout", record.Cwd, wantWorkDir)
+	}
+	if !strings.Contains(record.PromptFile, repoRoot) {
+		t.Fatalf("prompt file = %q, want reviewer checkout path %q", record.PromptFile, repoRoot)
 	}
 	if tools := flagValue(record.AdapterArgs, "--tools"); tools != "Read,Write,Bash" {
 		t.Fatalf("--tools = %q, want reviewer workspace tools", tools)