codetether_agent/

worktree.rs

//! Git worktree management for isolated agent execution
//!
//! Provides worktree isolation for parallel agent tasks.

use crate::provenance::{ExecutionOrigin, ExecutionProvenance, git_commit_with_provenance};
use anyhow::{Context, Result, anyhow};
use std::path::{Path, PathBuf};
use tokio::sync::Mutex;

/// Worktree information
#[derive(Debug, Clone)]
pub struct WorktreeInfo {
    /// Worktree name/identifier
    pub name: String,
    /// Path to the worktree
    pub path: PathBuf,
    /// Branch name
    pub branch: String,
    /// Whether this worktree is active
    #[allow(dead_code)]
    pub active: bool,
}

/// Worktree manager for creating and managing isolated git worktrees
#[derive(Debug)]
pub struct WorktreeManager {
    /// Base directory for worktrees
    base_dir: PathBuf,
    /// Path to the main repository
    repo_path: PathBuf,
    /// Active worktrees
    worktrees: Mutex<Vec<WorktreeInfo>>,
    /// Whether git object integrity was already verified for this manager
    integrity_checked: Mutex<bool>,
}

/// Merge result
#[derive(Debug, Clone)]
pub struct MergeResult {
    pub success: bool,
    pub aborted: bool,
    pub conflicts: Vec<String>,
    pub conflict_diffs: Vec<(String, String)>,
    pub files_changed: usize,
    pub summary: String,
}

impl WorktreeManager {
    /// Create a new worktree manager
    pub fn new(base_dir: impl Into<PathBuf>) -> Self {
        Self {
            base_dir: base_dir.into(),
            repo_path: std::env::current_dir().unwrap_or_else(|_| PathBuf::from(".")),
            worktrees: Mutex::new(Vec::new()),
            integrity_checked: Mutex::new(false),
        }
    }

    /// Create a worktree manager with explicit repo path
    #[allow(dead_code)]
    pub fn with_repo(base_dir: impl Into<PathBuf>, repo_path: impl Into<PathBuf>) -> Self {
        Self {
            base_dir: base_dir.into(),
            repo_path: repo_path.into(),
            worktrees: Mutex::new(Vec::new()),
            integrity_checked: Mutex::new(false),
        }
    }

    /// Create a new worktree for a task
    ///
    /// This creates an actual git worktree using `git worktree add`,
    /// creating a new branch if it doesn't exist.
    pub async fn create(&self, name: &str) -> Result<WorktreeInfo> {
        self.ensure_repo_integrity_once().await?;
        Self::validate_worktree_name(name)?;
        let worktree_path = self.base_dir.join(name);
        let branch_name = format!("codetether/{}", name);

        // Ensure base directory exists
        tokio::fs::create_dir_all(&self.base_dir)
            .await
            .with_context(|| {
                format!(
                    "Failed to create base directory: {}",
                    self.base_dir.display()
                )
            })?;

        // Run git worktree add
        let output = tokio::process::Command::new("git")
            .args(["worktree", "add", "-b", &branch_name])
            .arg(&worktree_path)
            .current_dir(&self.repo_path)
            .output()
            .await
            .context("Failed to execute git worktree add")?;

        if !output.status.success() {
            // Branch might already exist, try without -b
            let output2 = tokio::process::Command::new("git")
                .args(["worktree", "add"])
                .arg(&worktree_path)
                .arg(&branch_name)
                .current_dir(&self.repo_path)
                .output()
                .await
                .context("Failed to execute git worktree add (fallback)")?;

            if !output2.status.success() {
                return Err(anyhow!(
                    "Failed to create git worktree '{}': {}",
                    name,
                    String::from_utf8_lossy(&output2.stderr)
                ));
            }
        }

        let info = WorktreeInfo {
            name: name.to_string(),
            path: worktree_path.clone(),
            branch: branch_name,
            active: true,
        };

        let mut worktrees = self.worktrees.lock().await;
        worktrees.push(info.clone());

        tracing::info!(worktree = %name, path = %worktree_path.display(), "Created git worktree");
        Ok(info)
    }

    /// Verify repository object integrity before worktree operations.
    ///
    /// If corruption is detected, a best-effort repair is attempted automatically.
    pub async fn ensure_repo_integrity(&self) -> Result<()> {
        let first_check = self.run_repo_fsck().await?;
        if first_check.status.success() {
            return Ok(());
        }

        let first_output = Self::combined_output(&first_check.stdout, &first_check.stderr);
        if !Self::looks_like_object_corruption(&first_output) {
            return Err(anyhow!(
                "Git repository preflight failed: {}",
                Self::summarize_git_output(&first_output)
            ));
        }

        tracing::warn!(
            repo_path = %self.repo_path.display(),
            issue = %Self::summarize_git_output(&first_output),
            "Detected git object corruption; attempting automatic repair"
        );
        self.try_auto_repair().await;

        let second_check = self.run_repo_fsck().await?;
        if second_check.status.success() {
            tracing::info!(
                repo_path = %self.repo_path.display(),
                "Git repository integrity restored after automatic repair"
            );
            return Ok(());
        }

        let second_output = Self::combined_output(&second_check.stdout, &second_check.stderr);
        Err(Self::integrity_error_message(
            &self.repo_path,
            &second_output,
        ))
    }

    /// Get information about a worktree
    #[allow(dead_code)]
    pub async fn get(&self, name: &str) -> Option<WorktreeInfo> {
        let worktrees = self.worktrees.lock().await;
        worktrees.iter().find(|w| w.name == name).cloned()
    }

    /// List all worktrees
    pub async fn list(&self) -> Vec<WorktreeInfo> {
        self.worktrees.lock().await.clone()
    }

    /// Clean up a specific worktree
    pub async fn cleanup(&self, name: &str) -> Result<()> {
        // Clone info but keep tracking until IO succeeds
        let info = {
            let worktrees = self.worktrees.lock().await;
            match worktrees.iter().find(|w| w.name == name) {
                Some(w) => w.clone(),
                None => return Ok(()),
            }
        };
        let branch = info.branch.clone();

        // Run git worktree remove (no lock held)
        let output = tokio::process::Command::new("git")
            .args(["worktree", "remove", "--force"])
            .arg(&info.path)
            .current_dir(&self.repo_path)
            .output()
            .await;

        match output {
            Ok(o) if o.status.success() => {
                tracing::info!(worktree = %name, "Removed git worktree");
            }
            Ok(o) => {
                tracing::warn!(
                    worktree = %name,
                    error = %String::from_utf8_lossy(&o.stderr),
                    "Git worktree remove failed, falling back to directory removal"
                );
                if let Err(e) = tokio::fs::remove_dir_all(&info.path).await {
                    tracing::warn!(worktree = %name, error = %e, "Failed to remove worktree directory");
                }
            }
            Err(e) => {
                tracing::warn!(worktree = %name, error = %e, "Failed to execute git worktree remove");
                if let Err(e) = tokio::fs::remove_dir_all(&info.path).await {
                    tracing::warn!(worktree = %name, error = %e, "Failed to remove worktree directory");
                }
            }
        }

        // Delete the branch so it doesn't leak
        Self::delete_branch(&self.repo_path, &branch, None).await;
        Ok(())
    }

    /// Merge a worktree branch back into the current branch
    ///
    /// This performs an actual git merge operation and handles conflicts.
    pub async fn merge(&self, name: &str) -> Result<MergeResult> {
        let worktrees = self.worktrees.lock().await;
        let info = worktrees
            .iter()
            .find(|w| w.name == name)
            .ok_or_else(|| anyhow!("Worktree not found: {}", name))?;

        let branch = info.branch.clone();
        drop(worktrees); // Release lock before git operations

        // Pre-merge cleanup: reset any leftover unmerged index entries from
        // previous failed merges.  Without this, `git merge` refuses to start
        // ("Merging is not possible because you have unmerged files.").
        let umg = std::process::Command::new("git")
            .args(["diff", "--name-only", "--diff-filter=U"])
            .current_dir(&self.repo_path)
            .output()
            .context("Failed to check for unmerged files")?;
        if !String::from_utf8_lossy(&umg.stdout).trim().is_empty() {
            tracing::warn!("Resetting unmerged index entries before merge");
            // Abort any lingering merge state first
            let _ = std::process::Command::new("git")
                .args(["merge", "--abort"])
                .current_dir(&self.repo_path)
                .output();
            // Hard-reset the index to HEAD to clear unmerged entries
            let _ = std::process::Command::new("git")
                .args(["reset", "HEAD", "--"])
                .current_dir(&self.repo_path)
                .output();
            // Restore working tree files to match index
            let _ = std::process::Command::new("git")
                .args(["checkout", "--", "."])
                .current_dir(&self.repo_path)
                .output();
        }

        // Stash any uncommitted changes before merging to avoid conflicts
        let dirty = std::process::Command::new("git")
            .args(["diff", "--quiet"])
            .current_dir(&self.repo_path)
            .output();
        let has_dirty = dirty.is_err() || !dirty.unwrap().status.success();

        if has_dirty {
            tracing::info!("Stashing dirty working tree before merge");
            let stash_out = std::process::Command::new("git")
                .args(["stash", "--include-untracked"])
                .current_dir(&self.repo_path)
                .output()
                .context("Failed to execute git stash")?;
            if !stash_out.status.success() {
                tracing::warn!(
                    "Stash failed (may be no changes): {}",
                    String::from_utf8_lossy(&stash_out.stderr)
                );
            }
        }

        tracing::info!(worktree = %name, branch = %branch, "Starting git merge");

        // Stage the merge but stamp the final merge commit ourselves for provenance.
        // First attempt: normal merge.
        let mut output = tokio::process::Command::new("git")
            .args(["merge", "--no-ff", "--no-commit", &branch])
            .current_dir(&self.repo_path)
            .output()
            .await
            .context("Failed to execute git merge")?;

        let stdout = String::from_utf8_lossy(&output.stdout);
        let stderr = String::from_utf8_lossy(&output.stderr);

        // If the merge has conflicts, automatically resolve them by accepting
        // the incoming (theirs) version.  This avoids blocking the autonomous
        // loop on manual conflict resolution.
        if !output.status.success() && (stderr.contains("CONFLICT") || stdout.contains("CONFLICT"))
        {
            tracing::warn!(
                worktree = %name,
                "Merge has conflicts — auto-resolving with -X theirs"
            );
            // Abort the conflicted merge
            let _ = tokio::process::Command::new("git")
                .args(["merge", "--abort"])
                .current_dir(&self.repo_path)
                .output()
                .await;

            // Retry with -X theirs to auto-resolve
            output = tokio::process::Command::new("git")
                .args(["merge", "--no-ff", "--no-commit", "-X", "theirs", &branch])
                .current_dir(&self.repo_path)
                .output()
                .await
                .context("Failed to execute git merge -X theirs")?;
        }

        let stdout = String::from_utf8_lossy(&output.stdout);
        let stderr = String::from_utf8_lossy(&output.stderr);

        if output.status.success() {
            let commit_msg = format!("Merge branch '{}' into current branch", branch);
            let provenance =
                ExecutionProvenance::for_operation("worktree", ExecutionOrigin::LocalCli);
            let commit_output =
                git_commit_with_provenance(&self.repo_path, &commit_msg, Some(&provenance)).await?;
            if !commit_output.status.success() {
                let commit_stderr = String::from_utf8_lossy(&commit_output.stderr);
                let _ = Self::stash_pop(&self.repo_path);
                return Err(anyhow!("Git merge commit failed: {}", commit_stderr));
            }
            tracing::info!(worktree = %name, branch = %branch, "Git merge successful");

            // Pop stash after successful merge
            let _ = Self::stash_pop(&self.repo_path);

            // Get files changed count
            let files_changed = self.count_merge_files_changed().await.unwrap_or(0);

            Ok(MergeResult {
                success: true,
                aborted: false,
                conflicts: vec![],
                conflict_diffs: vec![],
                files_changed,
                summary: commit_msg,
            })
        } else {
            // Abort merge and restore stash
            let _ = tokio::process::Command::new("git")
                .args(["merge", "--abort"])
                .current_dir(&self.repo_path)
                .output()
                .await;
            let _ = Self::stash_pop(&self.repo_path);

            // Check for conflicts
            if stderr.contains("CONFLICT") || stdout.contains("CONFLICT") {
                tracing::warn!(worktree = %name, "Merge has conflicts");

                let conflicts = self.get_conflict_list().await?;
                let conflict_diffs = self.get_conflict_diffs().await?;

                Ok(MergeResult {
                    success: false,
                    aborted: false,
                    conflicts,
                    conflict_diffs,
                    files_changed: 0,
                    summary: "Merge has conflicts that need resolution".to_string(),
                })
            } else {
                Err(anyhow!("Git merge failed: {}", stderr))
            }
        }
    }

    /// Complete a merge after conflicts are resolved
    ///
    /// This commits the merge after the user has resolved conflicts.
    pub async fn complete_merge(&self, name: &str, commit_msg: &str) -> Result<MergeResult> {
        let worktrees = self.worktrees.lock().await;
        let info = worktrees
            .iter()
            .find(|w| w.name == name)
            .ok_or_else(|| anyhow!("Worktree not found: {}", name))?;

        let branch = info.branch.clone();
        drop(worktrees);

        // Check if we're in a merge state
        let merge_head = self.merge_head_path().await?;
        let in_merge = tokio::fs::try_exists(&merge_head).await.unwrap_or(false);

        if !in_merge {
            return Err(anyhow!("Not in a merge state. Use merge() first."));
        }

        // Commit the merge
        let provenance = ExecutionProvenance::for_operation("worktree", ExecutionOrigin::LocalCli);
        let output =
            git_commit_with_provenance(&self.repo_path, commit_msg, Some(&provenance)).await?;

        if output.status.success() {
            tracing::info!(worktree = %name, branch = %branch, "Merge completed");

            let files_changed = self.count_merge_files_changed().await.unwrap_or(0);

            Ok(MergeResult {
                success: true,
                aborted: false,
                conflicts: vec![],
                conflict_diffs: vec![],
                files_changed,
                summary: format!("Merge completed: {}", commit_msg),
            })
        } else {
            let stderr = String::from_utf8_lossy(&output.stderr);
            Err(anyhow!("Failed to complete merge: {}", stderr))
        }
    }

    /// Abort an in-progress merge
    pub async fn abort_merge(&self, name: &str) -> Result<()> {
        let worktrees = self.worktrees.lock().await;
        if !worktrees.iter().any(|w| w.name == name) {
            return Err(anyhow!("Worktree not found: {}", name));
        }
        drop(worktrees);

        // Check if we're in a merge state
        let merge_head = self.merge_head_path().await?;
        let in_merge = tokio::fs::try_exists(&merge_head).await.unwrap_or(false);

        if !in_merge {
            tracing::warn!("Not in a merge state, nothing to abort");
            return Ok(());
        }

        let output = tokio::process::Command::new("git")
            .args(["merge", "--abort"])
            .current_dir(&self.repo_path)
            .output()
            .await
            .context("Failed to execute git merge --abort")?;

        if output.status.success() {
            tracing::info!("Merge aborted");
            Ok(())
        } else {
            let stderr = String::from_utf8_lossy(&output.stderr);
            Err(anyhow!("Failed to abort merge: {}", stderr))
        }
    }

    fn validate_worktree_name(name: &str) -> Result<()> {
        if name.is_empty() {
            return Err(anyhow!("Worktree name cannot be empty"));
        }
        if name
            .chars()
            .all(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_')
        {
            return Ok(());
        }
        Err(anyhow!(
            "Invalid worktree name '{}'. Only alphanumeric characters, '-' and '_' are allowed.",
            name
        ))
    }

    async fn ensure_repo_integrity_once(&self) -> Result<()> {
        let mut checked = self.integrity_checked.lock().await;
        if *checked {
            return Ok(());
        }
        self.ensure_repo_integrity().await?;
        *checked = true;
        Ok(())
    }

    async fn run_repo_fsck(&self) -> Result<std::process::Output> {
        tokio::process::Command::new("git")
            .args(["fsck", "--full", "--no-dangling"])
            .current_dir(&self.repo_path)
            .output()
            .await
            .context("Failed to execute git fsck --full --no-dangling")
    }

    async fn try_auto_repair(&self) {
        self.run_repair_step(["fetch", "--all", "--prune", "--tags"])
            .await;
        self.run_repair_step(["worktree", "prune"]).await;
        self.run_repair_step(["gc", "--prune=now"]).await;
    }

    async fn run_repair_step<const N: usize>(&self, args: [&str; N]) {
        match tokio::process::Command::new("git")
            .args(args)
            .current_dir(&self.repo_path)
            .output()
            .await
        {
            Ok(output) if output.status.success() => {
                tracing::info!(
                    repo_path = %self.repo_path.display(),
                    command = %format!("git {}", args.join(" ")),
                    "Git repair step succeeded"
                );
            }
            Ok(output) => {
                tracing::warn!(
                    repo_path = %self.repo_path.display(),
                    command = %format!("git {}", args.join(" ")),
                    error = %Self::summarize_git_output(&Self::combined_output(
                        &output.stdout,
                        &output.stderr
                    )),
                    "Git repair step failed"
                );
            }
            Err(error) => {
                tracing::warn!(
                    repo_path = %self.repo_path.display(),
                    command = %format!("git {}", args.join(" ")),
                    error = %error,
                    "Failed to execute git repair step"
                );
            }
        }
    }

    fn integrity_error_message(repo_path: &Path, fsck_output: &str) -> anyhow::Error {
        let summary = Self::summarize_git_output(fsck_output);
        anyhow!(
            "Git object database is corrupted in '{}': {}\n\
Automatic repair was attempted but repository integrity is still broken.\n\
Recovery steps:\n\
1. Backup local changes: git diff > /tmp/codetether-recovery.patch\n\
2. Attempt object recovery: git fetch --all --prune --tags && git fsck --full\n\
3. If corruption remains, create a fresh clone and re-apply the patch.",
            repo_path.display(),
            summary
        )
    }

    fn combined_output(stdout: &[u8], stderr: &[u8]) -> String {
        let left = String::from_utf8_lossy(stdout);
        let right = String::from_utf8_lossy(stderr);
        format!("{left}\n{right}")
    }

    fn looks_like_object_corruption(output: &str) -> bool {
        let lower = output.to_ascii_lowercase();
        [
            "missing blob",
            "missing tree",
            "missing commit",
            "bad object",
            "unable to read",
            "object file",
            "hash mismatch",
            "broken link from",
            "corrupt",
            "invalid sha1 pointer",
            "fatal: loose object",
            "failed to parse commit",
        ]
        .iter()
        .any(|needle| lower.contains(needle))
    }

    fn summarize_git_output(output: &str) -> String {
        output
            .lines()
            .map(str::trim)
            .find(|line| !line.is_empty())
            .map(|line| line.chars().take(220).collect::<String>())
            .unwrap_or_else(|| "git command reported no details".to_string())
    }

    async fn merge_head_path(&self) -> Result<PathBuf> {
        let output = tokio::process::Command::new("git")
            .args(["rev-parse", "--git-path", "MERGE_HEAD"])
            .current_dir(&self.repo_path)
            .output()
            .await
            .context("Failed to determine git merge metadata path")?;

        if !output.status.success() {
            return Err(anyhow!(
                "Failed to resolve merge metadata path: {}",
                String::from_utf8_lossy(&output.stderr).trim()
            ));
        }

        let merge_head = String::from_utf8_lossy(&output.stdout).trim().to_string();
        if merge_head.is_empty() {
            return Err(anyhow!("Git returned an empty MERGE_HEAD path"));
        }

        let path = PathBuf::from(&merge_head);
        if path.is_absolute() {
            Ok(path)
        } else {
            Ok(self.repo_path.join(path))
        }
    }

    /// Clean up all worktrees
    pub async fn cleanup_all(&self) -> Result<usize> {
        // Clone list so tracking persists until IO succeeds
        let infos: Vec<WorktreeInfo> = {
            let worktrees = self.worktrees.lock().await;
            worktrees.clone()
        };
        let count = infos.len();

        for info in &infos {
            // Try git worktree remove first
            let _ = tokio::process::Command::new("git")
                .args(["worktree", "remove", "--force"])
                .arg(&info.path)
                .current_dir(&self.repo_path)
                .output()
                .await;

            // Fallback to directory removal
            if let Err(e) = tokio::fs::remove_dir_all(&info.path).await {
                tracing::warn!(worktree = %info.name, error = %e, "Failed to remove worktree directory");
            }
        }

        // Delete all branches so they don't leak
        for info in &infos {
            Self::delete_branch(&self.repo_path, &info.branch, None).await;
        }

        tracing::info!(count, "Cleaned up all worktrees");
        Ok(count)
    }

    /// Inject workspace stub for Cargo workspace isolation
    pub fn inject_workspace_stub(&self, _worktree_path: &Path) -> Result<()> {
        // Placeholder: In a real implementation, this would prepend [workspace] to Cargo.toml
        Ok(())
    }

    /// Delete a local branch and optionally its remote tracking ref (best-effort).
    ///
    /// Logs but does not propagate failures. Remote deletion is skipped when
    /// `remote` is `None` or when the push fails.
    async fn delete_branch(repo_path: &Path, branch: &str, remote: Option<&str>) {
        // Local branch deletion
        let out = tokio::process::Command::new("git")
            .args(["branch", "-D", branch])
            .current_dir(repo_path)
            .output()
            .await;
        match out {
            Ok(o) if o.status.success() => {
                tracing::info!(branch, "Deleted worktree branch");
            }
            Ok(o) => {
                let err = String::from_utf8_lossy(&o.stderr);
                tracing::debug!(branch, error = %err, "Branch delete skipped");
            }
            Err(e) => {
                tracing::debug!(branch, error = %e, "Branch delete failed");
            }
        }
        // Remote branch deletion (best-effort)
        if let Some(remote_name) = remote {
            let out = tokio::process::Command::new("git")
                .args(["push", remote_name, "--delete", branch])
                .current_dir(repo_path)
                .output()
                .await;
            match out {
                Ok(o) if o.status.success() => {
                    tracing::info!(
                        branch,
                        remote = remote_name,
                        "Deleted remote worktree branch"
                    );
                }
                Ok(o) => {
                    let err = String::from_utf8_lossy(&o.stderr);
                    tracing::debug!(
                        branch,
                        remote = remote_name,
                        error = %err,
                        "Remote branch delete skipped"
                    );
                }
                Err(e) => {
                    tracing::debug!(
                        branch,
                        remote = remote_name,
                        error = %e,
                        "Remote branch delete failed"
                    );
                }
            }
        }
    }

    /// Get list of conflicting files during a merge
    async fn get_conflict_list(&self) -> Result<Vec<String>> {
        let output = tokio::process::Command::new("git")
            .args(["diff", "--name-only", "--diff-filter=U"])
            .current_dir(&self.repo_path)
            .output()
            .await
            .context("Failed to get conflict list")?;

        let conflicts = String::from_utf8_lossy(&output.stdout)
            .lines()
            .map(String::from)
            .filter(|s| !s.is_empty())
            .collect();

        Ok(conflicts)
    }

    /// Get diffs for conflicting files
    async fn get_conflict_diffs(&self) -> Result<Vec<(String, String)>> {
        let conflicts = self.get_conflict_list().await?;
        let mut diffs = Vec::new();

        for file in conflicts {
            let output = tokio::process::Command::new("git")
                .args(["diff", &file])
                .current_dir(&self.repo_path)
                .output()
                .await;

            if let Ok(o) = output {
                let diff = String::from_utf8_lossy(&o.stdout).to_string();
                diffs.push((file, diff));
            }
        }

        Ok(diffs)
    }

    /// Count files changed in the last merge
    async fn count_merge_files_changed(&self) -> Result<usize> {
        let output = tokio::process::Command::new("git")
            .args(["diff", "--name-only", "HEAD~1", "HEAD"])
            .current_dir(&self.repo_path)
            .output()
            .await
            .context("Failed to count changed files")?;

        let count = String::from_utf8_lossy(&output.stdout)
            .lines()
            .filter(|s| !s.is_empty())
            .count();

        Ok(count)
    }

    /// Pop the most recent stash after a merge completes or fails.
    fn stash_pop(repo_path: &Path) -> Result<()> {
        let output = std::process::Command::new("git")
            .args(["stash", "pop"])
            .current_dir(repo_path)
            .output()
            .context("Failed to execute git stash pop")?;
        if !output.status.success() {
            tracing::warn!(
                "stash pop failed (may be empty stash): {}",
                String::from_utf8_lossy(&output.stderr)
            );
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::WorktreeManager;

    #[test]
    fn corruption_detection_matches_missing_blob() {
        let output = "error: missing blob 1234abcd";
        assert!(WorktreeManager::looks_like_object_corruption(output));
    }

    #[test]
    fn corruption_detection_ignores_non_corruption_errors() {
        let output = "fatal: not a git repository";
        assert!(!WorktreeManager::looks_like_object_corruption(output));
    }

    #[test]
    fn summarize_output_uses_first_non_empty_line() {
        let output = "\n\nfatal: bad object HEAD\nmore";
        assert_eq!(
            WorktreeManager::summarize_git_output(output),
            "fatal: bad object HEAD"
        );
    }
}

impl Default for WorktreeManager {
    fn default() -> Self {
        Self::new("/tmp/codetether-worktrees")
    }
}