wt/worktree/

service.rs

//! The stateless worktree service (issue #95): discover, enumerate, create,
//! and remove worktrees non-interactively.
//!
//! Nothing here prompts, reads stdin, or writes to stdout/stderr. Operations
//! take injected [`GitCli`] and [`HookRunner`] handles, return typed errors
//! from [`crate::error::Error`], and report side observations (hook failures,
//! submodule outcomes, copied files) as data on the outcome structs so callers
//! decide how to present them. The CLI commands and the TUI wrap this service
//! with prompting and rendering; embedders call it directly.

use std::path::{Path, PathBuf};
use std::time::Duration;

use crate::config::wtconfig::WtMeta;
use crate::config::{self, Config, wtconfig};
use crate::copy::{CopyOutcome, copy_ignored_files};
use crate::cx::Env;
use crate::error::{Error, Result};
use crate::git::cli::GitCli;
use crate::git::discover::Repo;
use crate::git::submodule::seed::SeedReport;
use crate::git::{branch_ref, default_branch, is_ancestor, ops, resolve_hex};
use crate::hooks::{HookContext, HookRunner};
use crate::model::Worktree;
use crate::query::{self, Resolved};
use crate::slug::slugify_with_fallback;
use crate::template::{self, TemplateVars};
use crate::worktree::{materialize, rows};

/// How long a mutation waits for the advisory repository lock (issue #99)
/// before failing with [`Error::LockUnavailable`].
const LOCK_TIMEOUT: Duration = Duration::from_secs(10);

/// A held advisory repository lock (issue #99): while alive, no other `wt` (or
/// embedder going through this library) can mutate worktrees or `wt.*`
/// metadata in the repository. Released on drop.
///
/// [`Workspace::create`] and [`Workspace::remove`] take the lock internally
/// around their mutation regions (hooks run *outside* it, so a hook that
/// re-enters `wt` cannot deadlock) — do not hold a `RepoLock` while calling
/// them. Take one directly to make your own read-check-write sequence over
/// `wt.*` metadata atomic against concurrent writers.
///
/// Acquiring the lock also validates the repository's metadata schema, so
/// every acquisition fails with [`Error::SchemaTooNew`] rather than hand back
/// a lock over a repository this build cannot interpret (issue #106).
pub struct RepoLock {
    _marker: gix_lock::Marker,
}

/// The directory holding the advisory lock file: the repository's common git
/// directory, shared by every linked worktree (`.git` of the primary worktree,
/// or the repository itself when bare).
fn lock_dir(root: &Path) -> PathBuf {
    let dot_git = root.join(".git");
    if dot_git.is_dir() {
        dot_git
    } else {
        root.to_path_buf()
    }
}

/// Re-reads the repository's metadata schema and refuses a version this build
/// cannot interpret.
///
/// The read goes through a *freshly opened* repository deliberately: `gix`
/// snapshots the git config when a repository is opened, so a handle obtained
/// before the lock cannot see a `wt.schema` bump that landed while the caller
/// waited for it (issue #106).
fn ensure_schema_supported_now(root: &Path) -> Result<()> {
    wtconfig::ensure_schema_supported(Repo::discover(root)?.gix())
}

/// Acquires the repo-level advisory mutation lock, waiting (with backoff) up
/// to `timeout` for a concurrent holder to finish.
///
/// The metadata schema is validated *after* the lock is held (issue #106), so
/// the gate covers the window it exists to protect: a concurrent `wt.schema`
/// bump either lands before the check and is refused, or is excluded until the
/// mutation finishes. Every mutating path takes the lock, so folding the check
/// in here is what makes "no mutation runs against an unsupported schema" hold
/// by construction rather than by each call site remembering to ask. A refusal
/// drops the lock on the way out, leaving nothing held.
pub(crate) fn acquire_repo_lock(root: &Path, timeout: Duration) -> Result<RepoLock> {
    let resource = lock_dir(root).join("wt-mutation");
    let marker = gix_lock::Marker::acquire_to_hold_resource(
        &resource,
        gix_lock::acquire::Fail::AfterDurationWithBackoff(timeout),
        None,
    )
    .map_err(|e| Error::LockUnavailable {
        path: format!("{}.lock", resource.display()),
        reason: e.to_string(),
    })?;
    let lock = RepoLock { _marker: marker };
    ensure_schema_supported_now(root)?;
    Ok(lock)
}

/// Acquires the repo-level advisory mutation lock with the standard timeout.
/// This is the form the command handlers use: they hold the repo root inside a
/// `Session` rather than a [`Workspace`], which is what [`Workspace::lock`]
/// serves for library consumers.
#[cfg(feature = "cli")]
pub(crate) fn lock_repo(root: &Path) -> Result<RepoLock> {
    acquire_repo_lock(root, LOCK_TIMEOUT)
}

/// A discovered repository with its resolved configuration and environment
/// snapshot: the entry point of the stateless worktree API.
pub struct Workspace {
    repo: Repo,
    primary_root: PathBuf,
    config: Config,
    env: Env,
}

/// Borrowed workspace state threaded through the service functions, so the CLI
/// (which owns the same parts inside its `Session`) can call them without
/// constructing a [`Workspace`].
pub(crate) struct WorkspaceParts<'a> {
    /// The discovered repository.
    pub(crate) repo: &'a Repo,
    /// The merged configuration.
    pub(crate) config: &'a Config,
    /// The primary worktree root (or bare repo path).
    pub(crate) root: &'a Path,
    /// The environment snapshot (template `{home}` expansion).
    pub(crate) env: &'a Env,
}

impl Workspace {
    /// Discovers the repository containing `dir`, resolves the primary worktree
    /// root, and loads the merged configuration. Returns
    /// [`Error::NotInRepo`] when `dir` is not inside a Git repository.
    pub fn discover(dir: &Path, env: &Env, git: &dyn GitCli) -> Result<Workspace> {
        let repo = Repo::discover(dir)?;
        let workdir = repo.current_workdir().unwrap_or_else(|| repo.git_dir());
        // `gix`'s common-dir resolution is unreliable through linked worktrees,
        // so the primary root comes from `git rev-parse` (spec §4).
        let common = git.run(
            &workdir,
            &["rev-parse", "--path-format=absolute", "--git-common-dir"],
        )?;
        let common = PathBuf::from(common.trim());
        let primary_root = if repo.is_bare() {
            common
        } else {
            common.parent().map(Path::to_path_buf).unwrap_or(common)
        };
        let config = config::load(Some(&primary_root), env)?;
        // Refuse a repository stamped with a future metadata schema up front
        // (issue #99); reading it could silently misinterpret `wt.*` keys.
        wtconfig::ensure_schema_supported(repo.gix())?;
        Ok(Workspace {
            repo,
            primary_root,
            config,
            env: env.clone(),
        })
    }

    /// Acquires the repository's advisory mutation lock (issue #99). See
    /// [`RepoLock`] for the holding rules.
    ///
    /// Fails with [`Error::SchemaTooNew`] when the repository is stamped with a
    /// metadata schema this build cannot interpret, re-read under the lock
    /// (issue #106) — so the version an embedder validated at discovery is
    /// still the version it holds the lock over.
    pub fn lock(&self) -> Result<RepoLock> {
        acquire_repo_lock(&self.primary_root, LOCK_TIMEOUT)
    }

    /// The primary worktree root (or the repository path when bare). This is
    /// the `repo_root` expected by the [`wtconfig`] write functions.
    pub fn root(&self) -> &Path {
        &self.primary_root
    }

    /// The merged configuration (defaults, global `config.toml`, repo
    /// `.wt.toml`).
    pub fn config(&self) -> &Config {
        &self.config
    }

    /// Whether the primary repository is bare.
    pub fn is_bare(&self) -> bool {
        self.repo.is_bare()
    }

    /// Enumerates worktrees with their synchronous fields only (path, branch,
    /// slug, current/main/missing/detached markers).
    pub fn enumerate(&self, git: &dyn GitCli) -> Result<Vec<Worktree>> {
        rows::enumerate_worktrees(&self.fresh_repo()?, git)
    }

    /// Enumerates worktrees fully enriched: dirty/untracked status,
    /// ahead/behind, merge state, tip commits, and the cached PR metadata from
    /// `wt.*` config.
    pub fn list(&self, git: &dyn GitCli) -> Result<Vec<Worktree>> {
        rows::build_worktrees(&self.fresh_repo()?, git)
    }

    /// Reads the `wt.*` metadata recorded for `branch`.
    pub fn read_meta(&self, branch: &str) -> Result<WtMeta> {
        Ok(wtconfig::read_meta(self.fresh_repo()?.gix(), branch))
    }

    /// Writes the `Some` fields of `update` to `branch`'s `wt.*` metadata,
    /// leaving every other recorded key alone (issue #95).
    ///
    /// The whole update is applied under the advisory repository lock (issue
    /// #99), so a concurrent writer never observes half a bundle — do not call
    /// this while already holding a [`RepoLock`]. To make a read-check-write
    /// sequence atomic, take [`Workspace::lock`] and drive the [`wtconfig`]
    /// setters directly instead.
    ///
    /// The schema gate is the lock's (issue #106): nothing here runs ahead of
    /// it, so there is no separate check to keep in step.
    pub fn write_meta(&self, git: &dyn GitCli, branch: &str, update: &MetaUpdate) -> Result<()> {
        let _lock = self.lock()?;
        apply_meta(git, &self.primary_root, branch, update)
    }

    /// Removes every `wt.<branch>.*` key, under the advisory repository lock.
    /// A branch with no recorded metadata is not an error.
    pub fn clear_meta(&self, git: &dyn GitCli, branch: &str) -> Result<()> {
        let _lock = self.lock()?;
        wtconfig::clear_meta(git, &self.primary_root, branch)
    }

    /// Creates (or reuses) a linked worktree per `options`: resolves the target
    /// from the configured path template, creates the branch off its base when
    /// needed, records `wt.*` metadata, runs the copy step, the `post_create`
    /// hook, and (when requested) submodule initialization. Partial failures
    /// before the hook are rolled back (spec §13).
    pub fn create(
        &self,
        git: &dyn GitCli,
        hooks: &dyn HookRunner,
        options: &CreateOptions,
    ) -> Result<CreatedWorktree> {
        let repo = self.fresh_repo()?;
        create_in(&self.parts(&repo), git, hooks, options)
    }

    /// Removes `worktree` under `options`, enforcing the dirty/unpushed safety
    /// guards (returning [`Error::RemoveGuarded`] when they block), running the
    /// `pre_remove` hook, pruning a missing worktree, and deleting a
    /// fully-merged wt-created branch per the configuration.
    pub fn remove(
        &self,
        git: &dyn GitCli,
        hooks: &dyn HookRunner,
        worktree: &Worktree,
        options: &RemoveOptions,
    ) -> Result<RemovedWorktree> {
        let repo = self.fresh_repo()?;
        remove_in(&self.parts(&repo), git, hooks, worktree, options)
    }

    /// Re-opens the repository for one operation. `gix` snapshots the git
    /// config when a repository is opened, while `wt.*` metadata is written
    /// through the `git` subprocess — a long-lived `Workspace` reading through
    /// the discovery-time handle would see stale metadata, so every operation
    /// reads through a fresh one.
    fn fresh_repo(&self) -> Result<Repo> {
        let dir = self
            .repo
            .current_workdir()
            .unwrap_or_else(|| self.repo.git_dir());
        Repo::discover(&dir)
    }

    /// The borrowed parts view of this workspace over `repo`.
    fn parts<'a>(&'a self, repo: &'a Repo) -> WorkspaceParts<'a> {
        WorkspaceParts {
            repo,
            config: &self.config,
            root: &self.primary_root,
            env: &self.env,
        }
    }

    /// Decomposes into the parts the CLI session keeps.
    #[cfg_attr(not(feature = "cli"), allow(dead_code))]
    pub(crate) fn into_session_parts(self) -> (Repo, PathBuf, Config) {
        (self.repo, self.primary_root, self.config)
    }
}

/// A `wt.<branch>.*` metadata update for [`Workspace::write_meta`]: every
/// `Some` field is written and every `None` field leaves the recorded value
/// untouched, so a caller refreshing one key cannot clobber the rest.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct MetaUpdate {
    /// The base ref the branch was created from (spec §3).
    pub base_ref: Option<String>,
    /// The associated PR number (spec §7).
    pub pr_number: Option<u64>,
    /// The cached PR state, so `wt list` can show it offline.
    pub pr_state: Option<String>,
    /// The cached PR title.
    pub pr_title: Option<String>,
    /// The cached PR URL.
    pub pr_url: Option<String>,
    /// The linked GitHub issue number (issue #100).
    pub issue_number: Option<u64>,
    /// The cached issue title.
    pub issue_title: Option<String>,
    /// The cached issue URL.
    pub issue_url: Option<String>,
    /// The generated implementation brief, persisted for embedders.
    pub issue_brief: Option<String>,
    /// Marks the branch as created by `wt` (spec §10), which is what allows a
    /// later remove to delete it. There is no un-marking: `false` leaves the
    /// recorded flag as it is.
    pub created_by_wt: bool,
}

/// Applies a [`MetaUpdate`] with no locking, for callers already inside a
/// locked mutation region ([`create_in`], the `wt pr` checkout path).
pub(crate) fn apply_meta(
    git: &dyn GitCli,
    root: &Path,
    branch: &str,
    update: &MetaUpdate,
) -> Result<()> {
    if let Some(base_ref) = &update.base_ref {
        wtconfig::write_base_ref(git, root, branch, base_ref)?;
    }
    if let Some(number) = update.pr_number {
        wtconfig::write_pr_number(git, root, branch, number)?;
    }
    if let Some(state) = &update.pr_state {
        wtconfig::write_pr_state(git, root, branch, state)?;
    }
    if let Some(title) = &update.pr_title {
        wtconfig::write_pr_title(git, root, branch, title)?;
    }
    if let Some(url) = &update.pr_url {
        wtconfig::write_pr_url(git, root, branch, url)?;
    }
    if let Some(number) = update.issue_number {
        wtconfig::write_issue_number(git, root, branch, number)?;
    }
    if let Some(title) = &update.issue_title {
        wtconfig::write_issue_title(git, root, branch, title)?;
    }
    if let Some(url) = &update.issue_url {
        wtconfig::write_issue_url(git, root, branch, url)?;
    }
    if let Some(brief) = &update.issue_brief {
        wtconfig::write_issue_brief(git, root, branch, brief)?;
    }
    if update.created_by_wt {
        wtconfig::mark_created_by_wt(git, root, branch)?;
    }
    Ok(())
}

/// Options for [`Workspace::create`].
#[derive(Debug, Clone, Default)]
pub struct CreateOptions {
    /// The branch to check out, created off `base` when it does not exist.
    pub branch: String,
    /// Explicit base ref for a new branch. `None` resolves the configured
    /// `default_base`, then the repository default branch, then `HEAD`.
    /// Ignored when the branch already exists.
    pub base: Option<String>,
    /// Set this ref as the new branch's upstream (`--track`).
    pub track: Option<String>,
    /// Copy-source worktree query (spec §8); `None` copies from the current
    /// worktree (or the primary root).
    pub copy_from: Option<String>,
    /// Initialize uninitialized submodules after creation. The service never
    /// prompts: callers resolve their `submodules.init` policy (and any flag
    /// override) to a boolean first.
    pub init_submodules: bool,
    /// Seed those submodules from the repository's own local object stores
    /// rather than re-cloning them from their remotes. Only an accelerator: the
    /// stock `submodule update --init --recursive` still runs afterwards and
    /// determines the result, so this cannot change the outcome. Resolved by the
    /// caller from `submodules.seed`. Ignored when `init_submodules` is false.
    pub seed_submodules: bool,
    /// Materialize the worktree by copy-on-write cloning an existing one's files
    /// rather than checking them out. Requires a CoW filesystem and a source
    /// worktree already at the same tree; when either is missing this silently
    /// uses the normal checkout. Resolved by the caller from `create.reflink`.
    pub reflink: bool,
    /// Skip the `post_create` hook.
    pub no_hooks: bool,
}

/// Options for [`Workspace::remove`]. The worktree-removal force is decoupled
/// from the branch-deletion force: the TUI confirm dialog forces removal of a
/// dirty worktree without ever force-deleting an unmerged branch (spec §10/§12).
#[derive(Debug, Clone, Copy, Default)]
pub struct RemoveOptions {
    /// Skip the dirty/unpushed guards and pass `--force` to
    /// `git worktree remove`.
    pub force_remove: bool,
    /// Permit deleting a branch that is not fully merged into its base.
    pub force_branch: bool,
    /// Always keep the local branch.
    pub keep_branch: bool,
    /// Skip the `pre_remove` hook.
    pub no_hooks: bool,
}

/// How a hook invocation went, reported as data (the service never prints).
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum HookOutcome {
    /// No hook was configured, hooks were disabled, or the operation's path
    /// does not run the hook (e.g. reusing an existing worktree).
    Skipped,
    /// The hook ran and exited zero.
    Succeeded,
    /// The hook ran and exited with this non-zero status.
    ExitedNonZero(i32),
    /// The hook could not be run at all.
    Failed(String),
}

/// How the post-create submodule initialization went.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum SubmodulesOutcome {
    /// Initialization was not requested or nothing was uninitialized.
    Skipped,
    /// This many pending submodules were initialized.
    Initialized(usize),
    /// Initialization was attempted for `pending` submodules but failed.
    /// Non-fatal: the worktree exists and is usable.
    Failed {
        /// How many submodules were uninitialized when the attempt started.
        pending: usize,
        /// The failure, rendered.
        error: String,
    },
}

/// What the local-mirror seeding step managed to do, as counts plus the
/// failures. Purely informational: seeding is always followed by a stock
/// `git submodule update --init --recursive`, so a non-empty `failed` here does
/// not mean the submodules are unpopulated.
///
/// Paths are relative to the worktree, so nested submodules read as
/// `outer/inner`.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
#[non_exhaustive]
pub struct SubmoduleSeeding {
    /// Submodules populated from a local mirror, sharing its objects.
    pub seeded: Vec<String>,
    /// Submodules with no local mirror, left to be cloned from their remote.
    pub skipped: Vec<String>,
    /// Submodules whose seeding failed, with the rendered error. The stock pass
    /// still had its chance to populate these.
    pub failed: Vec<(String, String)>,
}

impl From<SeedReport> for SubmoduleSeeding {
    fn from(report: SeedReport) -> Self {
        Self {
            seeded: report.seeded,
            skipped: report.skipped,
            failed: report.failed,
        }
    }
}

/// The outcome of [`Workspace::create`].
#[derive(Debug, Clone)]
#[non_exhaustive]
pub struct CreatedWorktree {
    /// The worktree's path.
    pub path: PathBuf,
    /// The checked-out branch.
    pub branch: String,
    /// The base the branch was created from, or `None` when it already
    /// existed.
    pub base_ref: Option<String>,
    /// Whether an existing worktree at the configured target was reused
    /// instead of created (the idempotent path; no copy step, no hook).
    pub reused: bool,
    /// What the copy step did (spec §8).
    pub copy: CopyOutcome,
    /// How the `post_create` hook went. Never fatal (spec §8).
    pub post_create: HookOutcome,
    /// How submodule initialization went. Never fatal.
    pub submodules: SubmodulesOutcome,
    /// What the local-mirror seeding accelerator did, if it ran.
    pub submodule_seeding: SubmoduleSeeding,
    /// Whether the worktree's content was copy-on-write cloned from an existing
    /// worktree rather than checked out. `false` covers both "not requested" and
    /// "requested but unavailable"; the result is identical either way.
    pub reflinked: bool,
}

/// The outcome of [`Workspace::remove`].
#[derive(Debug, Clone)]
#[non_exhaustive]
pub struct RemovedWorktree {
    /// Whether the local branch was deleted along with the worktree.
    pub branch_deleted: bool,
    /// Whether the dirty/unpushed guards would have blocked and were
    /// overridden by [`RemoveOptions::force_remove`] — the data-loss-risk case
    /// a caller should surface.
    pub forced_past_guards: bool,
    /// Whether `--force` was passed to `git worktree remove` solely because the
    /// worktree contained populated submodules, which git refuses to remove
    /// without it. Distinct from [`Self::forced_past_guards`]: no `wt` guard was
    /// overridden and there is no data-loss risk to report, so callers must not
    /// present this as a forced removal.
    pub forced_for_submodules: bool,
    /// How the `pre_remove` hook went. A failing hook aborts the removal
    /// (with a typed error) unless `force_remove` downgraded it to an outcome
    /// reported here.
    pub pre_remove: HookOutcome,
}

/// Resolves the base ref for a new branch: `explicit`, then the configured
/// `default_base`, then the repository default branch, then `HEAD`. The second
/// element is `true` on the final `HEAD` fallback, which callers may want to
/// surface as a warning.
pub(crate) fn resolve_base(repo: &Repo, config: &Config, explicit: Option<&str>) -> (String, bool) {
    if let Some(explicit) = explicit {
        return (explicit.to_string(), false);
    }
    if let Some(base) = &config.default_base {
        return (base.clone(), false);
    }
    if let Some(branch) = default_branch(repo.gix()) {
        return (branch, false);
    }
    ("HEAD".to_string(), true)
}

/// The path `create_in` would materialize `branch` at, without creating
/// anything.
///
/// Exists so a caller that previews the target before confirming (`wt issue`)
/// derives it from the same slug and template logic `create_in` uses, rather
/// than reimplementing it and drifting.
#[cfg(feature = "cli")]
pub(crate) fn preview_target(
    ws: &WorkspaceParts<'_>,
    branch: &str,
    base: Option<&str>,
) -> Result<std::path::PathBuf> {
    let (slug, _) = target_slug(ws, branch, base)?;
    render_target(ws.config, ws.root, branch, &slug, ws.env)
}

/// The directory slug for `branch`, derived exactly as [`create_in`] derives it.
///
/// The commit only matters for a branch name that slugifies to nothing, where it
/// is the fallback — but that is precisely the case a preview would otherwise get
/// wrong, so the rule is shared rather than restated: an existing branch keys off
/// its own tip, a new one off the base it will fork from.
fn target_slug(
    ws: &WorkspaceParts<'_>,
    branch: &str,
    base: Option<&str>,
) -> Result<(String, String)> {
    let commit = match resolve_hex(ws.repo.gix(), &branch_ref(branch)) {
        Some(oid) => oid,
        None => {
            let base_ref = resolve_base(ws.repo, ws.config, base).0;
            resolve_hex(ws.repo.gix(), &base_ref)
                .ok_or_else(|| Error::operation(format!("base ref {base_ref:?} not found")))?
        }
    };
    let short_hash = commit.get(..7).unwrap_or(&commit).to_string();
    let slug = slugify_with_fallback(branch, &short_hash);
    Ok((slug, short_hash))
}

/// Creates (or reuses) a worktree per `options`; see [`Workspace::create`].
pub(crate) fn create_in(
    ws: &WorkspaceParts<'_>,
    git: &dyn GitCli,
    hooks: &dyn HookRunner,
    options: &CreateOptions,
) -> Result<CreatedWorktree> {
    // Refuse an unsupported schema before the enumeration and base resolution
    // below, so a stamped repository fails fast. This is only the fast path:
    // the authoritative gate runs under the lock (issue #106), because a bump
    // can still land between here and the acquisition.
    wtconfig::ensure_schema_supported(ws.repo.gix())?;
    let branch = options.branch.clone();
    let worktrees = rows::enumerate_worktrees(ws.repo, git)?;
    let branch_exists = resolve_hex(ws.repo.gix(), &branch_ref(&branch)).is_some();

    let base_ref = if branch_exists {
        None
    } else {
        Some(resolve_base(ws.repo, ws.config, options.base.as_deref()).0)
    };
    // Shared with `preview_target`, so a confirmation preview cannot name a
    // different directory than the one that gets created. This also performs the
    // base-ref existence check, erroring before anything is created.
    let (slug, short_hash) = target_slug(ws, &branch, options.base.as_deref())?;

    // If the branch is already checked out, either reuse (same target) or
    // refuse. The reuse path is idempotent: no copy step, no hook.
    if let Some(existing) = worktrees
        .iter()
        .find(|w| w.branch.as_deref() == Some(branch.as_str()))
    {
        let preview = render_target(ws.config, ws.root, &branch, &slug, ws.env)?;
        if same_path(&existing.path, &preview) {
            return Ok(CreatedWorktree {
                path: existing.path.clone(),
                branch,
                base_ref: None,
                reused: true,
                copy: CopyOutcome::default(),
                post_create: HookOutcome::Skipped,
                submodules: SubmodulesOutcome::Skipped,
                submodule_seeding: SubmoduleSeeding::default(),
                reflinked: false,
            });
        }
        return Err(Error::operation(format!(
            "branch {branch:?} is already checked out at {}",
            existing.path.display()
        )));
    }

    // The mutation region — target resolution through metadata + copy — runs
    // under the advisory repository lock (issue #99) so two concurrent
    // creators cannot interleave into a corrupt state. The lock is released
    // before the hook runs: a hook that re-enters `wt` must not deadlock.
    let lock = acquire_repo_lock(ws.root, LOCK_TIMEOUT)?;
    let target = resolve_target(
        ws.config,
        ws.root,
        &branch,
        &slug,
        &short_hash,
        ws.env,
        ws.repo.is_bare(),
    )?;
    if let Some(parent) = target.parent() {
        std::fs::create_dir_all(parent)?;
    }

    // Decide up front whether the content can be cloned copy-on-write from an
    // existing worktree instead of checked out. This has to happen before the
    // add, because the CoW path needs `--no-checkout`. `None` is the normal
    // checkout and is never an error.
    let reflink_plan = if options.reflink {
        let source = copy_source(ws, &worktrees, options.copy_from.as_deref()).ok();
        target
            .parent()
            .and_then(|parent| materialize::plan(source.as_deref(), parent))
    } else {
        None
    };
    let no_checkout = reflink_plan.is_some();

    // Create the worktree (git is atomic here).
    let target_str = target.to_string_lossy().into_owned();
    if let Some(base) = &base_ref {
        // `--no-track` keeps the new branch from inheriting the base as its
        // upstream (issue #43); `--track` opts into an explicit one.
        ops::worktree_add_branch(git, ws.root, &branch, &target_str, base, true, no_checkout)?;
    } else {
        ops::worktree_add(git, ws.root, &target_str, &branch, no_checkout)?;
    }

    // Materialize the content. A failure inside falls back to a stock checkout,
    // so the worktree is populated either way; only a failure to do even that
    // is fatal, and it rolls back like any other post-add step.
    let reflinked = match &reflink_plan {
        Some(plan) => match materialize::apply(git, &target, plan) {
            Ok(used_cow) => used_cow,
            Err(e) => {
                rollback_worktree(git, ws.root, &target, &branch, base_ref.is_some(), false);
                return Err(e);
            }
        },
        None => false,
    };

    // Steps after creation but before the hook are rolled back on failure (§13).
    let copy = match post_create_steps(ws, git, &worktrees, &branch, &base_ref, &target, options) {
        Ok(outcome) => outcome,
        Err(e) => {
            // Metadata is written only for a wt-created branch, so delete the
            // branch and clear metadata together on that condition.
            let created = base_ref.is_some();
            rollback_worktree(git, ws.root, &target, &branch, created, created);
            return Err(e);
        }
    };
    drop(lock);

    // The post-create hook: a failure is an outcome, not a rollback (§8).
    let ctx = HookContext {
        worktree_path: target.clone(),
        branch: branch.clone(),
        repo_root: ws.root.to_path_buf(),
        base_ref: base_ref.clone(),
        pr_number: None,
    };
    let post_create = match (options.no_hooks, ws.config.hooks_post_create.as_deref()) {
        (true, _) | (false, None) => HookOutcome::Skipped,
        (false, Some(command)) => match hooks.run(command, &ctx) {
            Ok(0) => HookOutcome::Succeeded,
            Ok(code) => HookOutcome::ExitedNonZero(code),
            Err(e) => HookOutcome::Failed(e.to_string()),
        },
    };

    // A copy-on-write materialization also brought the submodules' *files*
    // across, but their `.git` gitlinks still point into the source worktree.
    // Give them git directories of their own so the pass below recognizes them
    // instead of cloning over the top. Best-effort — anything missed is just a
    // normal clone.
    let attached = match reflinked.then(|| common_git_dir(git, ws.root)) {
        Some(Ok(common)) => materialize::attach_submodules(git, &target, &common),
        _ => Vec::new(),
    };
    if !attached.is_empty() {
        tracing::debug!(count = attached.len(), "attached copied submodules");
    }

    // Attaching clones each submodule from the repository's own mirror, which
    // records that mirror path as its `origin`. That has to be undone here, not
    // left to the pass below: an attached submodule reports as *initialized*, so
    // the pass sees nothing pending and skips — and mirror paths left as origins
    // would silently fetch from, and push into, the primary worktree's object
    // store instead of the real upstream.
    let attach_sync = if attached.is_empty() {
        Ok(())
    } else {
        crate::git::submodule::sync(git, &target)
    };

    // Submodule initialization, when the caller resolved its policy to "yes".
    // Non-fatal: the worktree already exists.
    let (submodules, seed) = match attach_sync {
        Err(e) => (
            SubmodulesOutcome::Failed {
                pending: attached.len(),
                error: e.to_string(),
            },
            SeedReport::default(),
        ),
        Ok(()) if options.init_submodules => {
            populate_submodules(git, &target, options.seed_submodules)?
        }
        Ok(()) => (SubmodulesOutcome::Skipped, SeedReport::default()),
    };

    Ok(CreatedWorktree {
        path: target,
        branch,
        base_ref,
        reused: false,
        copy,
        post_create,
        submodules,
        submodule_seeding: seed.into(),
        reflinked,
    })
}

/// The repository's common git directory — the shared `.git` that holds
/// `modules/`, as opposed to a linked worktree's private git dir.
fn common_git_dir(git: &dyn GitCli, root: &Path) -> Result<PathBuf> {
    let out = git.run(
        root,
        &["rev-parse", "--path-format=absolute", "--git-common-dir"],
    )?;
    Ok(PathBuf::from(out.trim()))
}

/// Populates `target`'s submodules, seeding from the repository's own local
/// mirrors first when enabled. See [`crate::git::submodule::populate`] for why
/// seeding cannot change the outcome.
fn populate_submodules(
    git: &dyn GitCli,
    target: &Path,
    seed_enabled: bool,
) -> Result<(SubmodulesOutcome, SeedReport)> {
    let pending = crate::git::submodule::uninitialized(git, target)?;
    if pending.is_empty() {
        return Ok((SubmodulesOutcome::Skipped, SeedReport::default()));
    }
    let (seed, result) = crate::git::submodule::populate(git, target, seed_enabled);
    let outcome = match result {
        Ok(()) => SubmodulesOutcome::Initialized(pending.len()),
        Err(e) => SubmodulesOutcome::Failed {
            pending: pending.len(),
            error: e.to_string(),
        },
    };
    Ok((outcome, seed))
}

/// Records metadata, sets an explicit upstream, and runs the copy step — the
/// region rolled back when any step fails.
fn post_create_steps(
    ws: &WorkspaceParts<'_>,
    git: &dyn GitCli,
    worktrees: &[Worktree],
    branch: &str,
    base_ref: &Option<String>,
    target: &Path,
    options: &CreateOptions,
) -> Result<CopyOutcome> {
    if let Some(base) = base_ref {
        // A wt-created branch records its base and "created by wt" (§3/§10).
        // The caller already holds the repo lock, so this applies the bundle
        // directly rather than through `Workspace::write_meta`.
        apply_meta(
            git,
            ws.root,
            branch,
            &MetaUpdate {
                base_ref: Some(base.clone()),
                created_by_wt: true,
                ..MetaUpdate::default()
            },
        )?;
    }
    // `--track <REF>` sets an explicit upstream (issue #43); a bad ref fails
    // here, inside the rolled-back region.
    if let Some(upstream) = &options.track {
        ops::set_upstream(git, ws.root, branch, upstream)?;
    }
    let source = copy_source(ws, worktrees, options.copy_from.as_deref())?;
    copy_ignored_files(git, &source, target, &ws.config.copy)
}

/// Resolves the copy source worktree: the `copy_from` query, else the current
/// worktree, else the primary root (spec §8).
fn copy_source(
    ws: &WorkspaceParts<'_>,
    worktrees: &[Worktree],
    copy_from: Option<&str>,
) -> Result<PathBuf> {
    if let Some(q) = copy_from {
        return match query::resolve(worktrees, q) {
            Resolved::One(index) => Ok(worktrees[index].path.clone()),
            Resolved::Ambiguous(_) => {
                Err(Error::operation(format!("--copy-from {q:?} is ambiguous")))
            }
            Resolved::NotFound => Err(Error::NotFound {
                query: q.to_string(),
            }),
        };
    }
    Ok(ws
        .repo
        .current_workdir()
        .unwrap_or_else(|| ws.root.to_path_buf()))
}

/// Removes an already-resolved `worktree`; see [`Workspace::remove`].
pub(crate) fn remove_in(
    ws: &WorkspaceParts<'_>,
    git: &dyn GitCli,
    hooks: &dyn HookRunner,
    worktree: &Worktree,
    options: &RemoveOptions,
) -> Result<RemovedWorktree> {
    // This one is load-bearing outside the lock: the `wt.*` metadata read just
    // below, the guards, and the `pre_remove` hook all run before the lock is
    // taken (a hook that re-enters `wt` must not deadlock, issue #99), and
    // reading `wt.*` under an unsupported schema could misinterpret it. The
    // mutation itself is gated again under the lock (issue #106).
    wtconfig::ensure_schema_supported(ws.repo.gix())?;
    if worktree.is_main {
        return Err(Error::operation("refusing to remove the primary worktree"));
    }
    let meta = worktree
        .branch
        .as_deref()
        .map(|b| wtconfig::read_meta(ws.repo.gix(), b))
        .unwrap_or_default();
    let default = default_branch(ws.repo.gix());

    // A missing worktree: prune the admin record; no guards or hook apply.
    if worktree.is_missing {
        let _lock = acquire_repo_lock(ws.root, LOCK_TIMEOUT)?;
        ops::worktree_prune(git, ws.root)?;
        let branch_deleted = maybe_delete_branch(ws, git, worktree, &meta, options, &default);
        clear_metadata(git, ws.root, worktree);
        return Ok(RemovedWorktree {
            branch_deleted,
            forced_past_guards: false,
            forced_for_submodules: false,
            pre_remove: HookOutcome::Skipped,
        });
    }

    // `git worktree remove` refuses outright — `fatal: working trees containing
    // submodules cannot be moved or removed` — for *any* worktree with a
    // populated submodule, dirty or not, and only `--force` gets past it.
    let needs_submodule_force =
        crate::git::submodule::any_initialized(git, &worktree.path).unwrap_or(false);

    // Safety guards (spec §10/§12). Forcing git past the submodule refusal also
    // takes its refusal to delete a worktree holding *untracked* files with it,
    // and `remove.untracked_blocks` is off by default — so count untracked files
    // here whenever that force is what we are about to do. Otherwise a worktree
    // with submodules would quietly lose files that an identical worktree
    // without them is protected from losing.
    let untracked_blocks = ws.config.remove_untracked_blocks || needs_submodule_force;
    let guard = rows::guard_status(worktree, untracked_blocks);
    if guard.blocks() && !options.force_remove {
        return Err(Error::RemoveGuarded {
            dirty: guard.dirty,
            unpushed: guard.unpushed,
        });
    }
    let forced_past_guards = guard.blocks() && options.force_remove;
    // Git needed forcing, but no `wt` guard was overridden to get there: no
    // data-loss risk to report, so this must not read as a forced removal.
    let forced_for_submodules = needs_submodule_force && !options.force_remove;

    // The pre-remove hook may abort; `force_remove` downgrades a failure to an
    // outcome and proceeds.
    let ctx = HookContext {
        worktree_path: worktree.path.clone(),
        branch: worktree.branch.clone().unwrap_or_default(),
        repo_root: ws.root.to_path_buf(),
        base_ref: meta.base_ref.clone(),
        pr_number: meta.pr_number,
    };
    let pre_remove = match (options.no_hooks, ws.config.hooks_pre_remove.as_deref()) {
        (true, _) | (false, None) => HookOutcome::Skipped,
        (false, Some(command)) => match hooks.run(command, &ctx) {
            Ok(0) => HookOutcome::Succeeded,
            Ok(code) if options.force_remove => HookOutcome::ExitedNonZero(code),
            Ok(code) => {
                return Err(Error::operation(format!(
                    "pre_remove hook exited with status {code}; aborting (use --force to override)"
                )));
            }
            Err(e) if options.force_remove => HookOutcome::Failed(e.to_string()),
            Err(e) => return Err(e),
        },
    };

    // Remove the worktree, holding the advisory lock (issue #99). Acquired
    // *after* the hook so a hook that re-enters `wt` cannot deadlock.
    let _lock = acquire_repo_lock(ws.root, LOCK_TIMEOUT)?;
    let path = worktree.path.to_string_lossy().into_owned();

    // The guards above are the real safety decision, and they took the submodule
    // force into account, so passing it to git now weakens nothing.
    ops::worktree_remove(
        git,
        ws.root,
        &path,
        options.force_remove || needs_submodule_force,
        false,
    )?;

    let branch_deleted = maybe_delete_branch(ws, git, worktree, &meta, options, &default);
    clear_metadata(git, ws.root, worktree);
    Ok(RemovedWorktree {
        branch_deleted,
        forced_past_guards,
        forced_for_submodules,
        pre_remove,
    })
}

/// Deletes the branch if it is wt-created and either fully merged (and the
/// config allows it) or `force_branch` (for an unmerged branch). Returns
/// whether the branch was deleted.
fn maybe_delete_branch(
    ws: &WorkspaceParts<'_>,
    git: &dyn GitCli,
    worktree: &Worktree,
    meta: &WtMeta,
    options: &RemoveOptions,
    default: &Option<String>,
) -> bool {
    let Some(branch) = &worktree.branch else {
        return false;
    };
    if options.keep_branch || !meta.created_by_wt {
        return false;
    }
    let base = meta.base_ref.clone().or_else(|| default.clone());
    let merged = base
        .as_deref()
        .is_some_and(|b| is_ancestor(ws.repo.gix(), &branch_ref(branch), b));
    let should_delete = if merged {
        ws.config.remove_delete_merged_branch
    } else {
        options.force_branch
    };
    if !should_delete {
        return false;
    }
    ops::delete_branch(git, ws.root, branch, true).is_ok()
}

/// Clears the worktree's `wt.*` metadata, best-effort.
fn clear_metadata(git: &dyn GitCli, root: &Path, worktree: &Worktree) {
    if let Some(branch) = &worktree.branch {
        let _ = wtconfig::clear_meta(git, root, branch);
    }
}

/// Whether two paths refer to the same location, comparing canonicalized forms
/// when possible (handles `/private` symlinks on macOS).
pub(crate) fn same_path(a: &Path, b: &Path) -> bool {
    let canon = |p: &Path| std::fs::canonicalize(p).unwrap_or_else(|_| p.to_path_buf());
    canon(a) == canon(b)
}

/// The git directory used for the `.git`-containment check (spec §6).
pub(crate) fn git_dir_of(root: &Path, is_bare: bool) -> PathBuf {
    if is_bare {
        root.to_path_buf()
    } else {
        root.join(".git")
    }
}

/// Renders the worktree store path for a branch with the given slug (spec §6).
pub(crate) fn render_target(
    config: &Config,
    root: &Path,
    branch: &str,
    slug: &str,
    env: &Env,
) -> Result<PathBuf> {
    let vars = TemplateVars {
        repo_parent: root
            .parent()
            .map_or_else(|| root.to_path_buf(), Path::to_path_buf),
        repo: root
            .file_name()
            .map(|n| n.to_string_lossy().into_owned())
            .unwrap_or_default(),
        repo_root: root.to_path_buf(),
        branch: branch.to_string(),
        branch_slug: slug.to_string(),
        home: env
            .get("HOME")
            .map(PathBuf::from)
            .unwrap_or_else(|| PathBuf::from("~")),
    };
    template::render(&config.path_template, &vars)
}

/// Resolves the final target path: renders it, rejects the `.git` directory,
/// and on collision with an unrelated path appends `-<short_hash>` (erroring if
/// both are occupied). Spec §6.
pub(crate) fn resolve_target(
    config: &Config,
    root: &Path,
    branch: &str,
    slug: &str,
    short_hash: &str,
    env: &Env,
    is_bare: bool,
) -> Result<PathBuf> {
    let target = render_target(config, root, branch, slug, env)?;
    template::ensure_outside_git(&target, &git_dir_of(root, is_bare))?;
    if !target.exists() {
        return Ok(target);
    }
    let alt = render_target(config, root, branch, &format!("{slug}-{short_hash}"), env)?;
    if alt.exists() {
        return Err(Error::operation(format!(
            "target path already exists: {}",
            target.display()
        )));
    }
    Ok(alt)
}

/// Runs a best-effort cleanup git command: on failure it logs a breadcrumb and
/// continues rather than aborting the caller. Used by the rollback and prune
/// cleanup paths, where a failed step must not stop the wider operation. `step`
/// is a short label identifying the command in the log.
pub(crate) fn run_best_effort(git: &dyn GitCli, root: &Path, args: &[&str], step: &str) {
    match git.run_raw(root, args) {
        Ok(out) if out.success => {}
        Ok(out) => {
            tracing::debug!(step, stderr = %out.stderr.trim(), "best-effort cleanup step failed");
        }
        Err(error) => {
            tracing::debug!(step, %error, "best-effort cleanup step could not run");
        }
    }
}

/// Rolls back a partially-created worktree (spec §13): removes the worktree and
/// prunes, optionally deletes the branch (only when it was created here), and
/// optionally clears the `wt.*` metadata written during the operation, so
/// nothing half-created is left behind. The two flags are independent: `wt pr`
/// on a *pre-existing* branch keeps the branch but still clears the metadata it
/// wrote. Best-effort.
pub(crate) fn rollback_worktree(
    git: &dyn GitCli,
    root: &Path,
    target: &Path,
    branch: &str,
    delete_branch: bool,
    clear_meta: bool,
) {
    let target_str = target.to_string_lossy();
    run_best_effort(
        git,
        root,
        &["worktree", "remove", "--force", &target_str],
        "rollback: worktree remove",
    );
    run_best_effort(
        git,
        root,
        &["worktree", "prune"],
        "rollback: worktree prune",
    );
    if delete_branch {
        run_best_effort(
            git,
            root,
            &["branch", "-D", branch],
            "rollback: branch delete",
        );
    }
    if clear_meta {
        // Remove the metadata written before the failure (else a later worktree
        // on this branch name would show stale PR/base info, or a wrongly-set
        // `createdByWt` could cause its branch to be deleted on remove).
        let _ = wtconfig::clear_meta(git, root, branch);
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::git::cli::RealGit;
    use crate::hooks::RealHookRunner;
    use crate::testutil::{TestRepo, give_upstream};
    use std::collections::HashMap;

    fn env() -> Env {
        Env::from_map(HashMap::new())
    }

    fn workspace(repo: &TestRepo) -> Workspace {
        Workspace::discover(repo.root(), &env(), &RealGit).unwrap()
    }

    fn create_opts(branch: &str) -> CreateOptions {
        CreateOptions {
            branch: branch.to_string(),
            no_hooks: true,
            ..Default::default()
        }
    }

    #[test]
    fn discover_resolves_root_config_and_bareness() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        assert!(!ws.is_bare());
        assert_eq!(
            std::fs::canonicalize(ws.root()).unwrap(),
            std::fs::canonicalize(repo.root()).unwrap()
        );
        assert_eq!(ws.config().pr_default_remote, "origin");
    }

    #[test]
    fn discover_outside_a_repo_is_not_in_repo() {
        let dir = tempfile::tempdir().unwrap();
        assert!(matches!(
            Workspace::discover(dir.path(), &env(), &RealGit),
            Err(Error::NotInRepo)
        ));
    }

    #[test]
    fn discover_from_linked_worktree_finds_primary_root() {
        let repo = TestRepo::init();
        repo.add_worktree("feature/x", "../wt-x");
        let linked = repo.root().parent().unwrap().join("wt-x");
        let ws = Workspace::discover(&linked, &env(), &RealGit).unwrap();
        assert_eq!(
            std::fs::canonicalize(ws.root()).unwrap(),
            std::fs::canonicalize(repo.root()).unwrap()
        );
    }

    #[test]
    fn create_new_branch_records_metadata_and_copies_nothing() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let created = ws
            .create(&RealGit, &RealHookRunner, &create_opts("feature/login"))
            .unwrap();
        assert!(!created.reused);
        assert_eq!(created.branch, "feature/login");
        assert_eq!(created.base_ref.as_deref(), Some("main"));
        assert!(created.path.is_dir());
        assert!(
            created.path.ends_with("feature-login")
                || created.path.to_string_lossy().contains("feature-login")
        );
        assert_eq!(created.post_create, HookOutcome::Skipped);
        assert_eq!(created.submodules, SubmodulesOutcome::Skipped);
        assert!(created.copy.copied.is_empty());
        let meta = ws.read_meta("feature/login").unwrap();
        assert_eq!(meta.base_ref.as_deref(), Some("main"));
        assert!(meta.created_by_wt);
    }

    #[test]
    fn create_existing_branch_does_not_mark_created() {
        let repo = TestRepo::init();
        repo.git(&["branch", "existing"]);
        let ws = workspace(&repo);
        let created = ws
            .create(&RealGit, &RealHookRunner, &create_opts("existing"))
            .unwrap();
        assert!(created.base_ref.is_none());
        assert!(!ws.read_meta("existing").unwrap().created_by_wt);
    }

    #[test]
    fn create_is_idempotent_at_the_same_target() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let first = ws
            .create(&RealGit, &RealHookRunner, &create_opts("feature/x"))
            .unwrap();
        let second = ws
            .create(&RealGit, &RealHookRunner, &create_opts("feature/x"))
            .unwrap();
        assert!(!first.reused);
        assert!(second.reused);
        assert_eq!(second.path, first.path);
        assert_eq!(second.post_create, HookOutcome::Skipped);
    }

    #[test]
    fn create_refuses_branch_checked_out_elsewhere() {
        let repo = TestRepo::init();
        repo.add_worktree("dup", "../manual-dup");
        let ws = workspace(&repo);
        let err = ws
            .create(&RealGit, &RealHookRunner, &create_opts("dup"))
            .unwrap_err();
        assert!(err.to_string().contains("already checked out"));
    }

    // `preview_target` exists for the CLI's confirmation preview, so its tests
    // only compile where it does.
    #[cfg(feature = "cli")]
    #[test]
    fn preview_target_names_the_directory_create_actually_makes() {
        // The slug's commit is only consulted for a branch name that slugifies to
        // nothing — and there a *new* branch keys off the base it forks from, not
        // off itself. A preview deriving the hash from the (absent) branch would
        // name a different directory than the one created, so `wt issue` would
        // confirm one path and produce another.
        // "_" is a legal git branch name whose slug is empty, so it is the case
        // that actually consults the commit hash.
        for branch in ["feat/7-add-login", "_"] {
            let repo = TestRepo::init();
            let ws = workspace(&repo);
            let fresh = Repo::discover(repo.root()).unwrap();
            let previewed = preview_target(&ws.parts(&fresh), branch, None).unwrap();
            let created = ws
                .create(&RealGit, &RealHookRunner, &create_opts(branch))
                .unwrap();
            assert_eq!(
                previewed, created.path,
                "preview and creation disagree for {branch:?}"
            );
        }
    }

    #[test]
    fn a_slugless_branch_is_named_after_the_base_it_forks_from() {
        // Rule 5 of the slug contract: an empty slug falls back to the short hash
        // of the *base ref*, not of the branch (which does not exist yet). Pinned
        // separately from the preview test, which can only prove the two agree —
        // not that the rule they share is the right one.
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let base = Repo::discover(repo.root())
            .ok()
            .and_then(|r| resolve_hex(r.gix(), "main"))
            .expect("main resolves");
        let short = &base[..7];

        let created = ws
            .create(&RealGit, &RealHookRunner, &create_opts("_"))
            .unwrap();
        let name = created
            .path
            .file_name()
            .map(|n| n.to_string_lossy().into_owned())
            .unwrap_or_default();
        assert!(
            name.ends_with(short),
            "{name} should end with the base short hash {short}"
        );
    }

    #[test]
    fn create_with_explicit_base_records_it() {
        let repo = TestRepo::init();
        repo.git(&["branch", "base-branch"]);
        let ws = workspace(&repo);
        let mut opts = create_opts("derived");
        opts.base = Some("base-branch".into());
        let created = ws.create(&RealGit, &RealHookRunner, &opts).unwrap();
        assert_eq!(created.base_ref.as_deref(), Some("base-branch"));
        assert_eq!(
            ws.read_meta("derived").unwrap().base_ref.as_deref(),
            Some("base-branch")
        );
    }

    #[test]
    fn create_with_unknown_base_errors() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let mut opts = create_opts("orphan");
        opts.base = Some("no-such-ref".into());
        let err = ws.create(&RealGit, &RealHookRunner, &opts).unwrap_err();
        assert!(err.to_string().contains("not found"));
    }

    #[test]
    fn create_reports_hook_outcomes_without_failing() {
        let repo = TestRepo::init();
        repo.write(".wt.toml", "[hooks]\npost_create = \"exit 3\"\n");
        repo.commit_all("config");
        let ws = workspace(&repo);
        let mut opts = create_opts("hooked");
        opts.no_hooks = false;
        let created = ws.create(&RealGit, &RealHookRunner, &opts).unwrap();
        assert_eq!(created.post_create, HookOutcome::ExitedNonZero(3));
        assert!(created.path.is_dir());
    }

    #[test]
    fn create_copies_ignored_files() {
        let repo = TestRepo::init();
        std::fs::write(repo.root().join(".wt.toml"), "copy = [\".env\"]\n").unwrap();
        repo.write(".env", "SECRET=1\n");
        let ws = workspace(&repo);
        let created = ws
            .create(&RealGit, &RealHookRunner, &create_opts("withenv"))
            .unwrap();
        assert_eq!(created.copy.copied.len(), 1);
        assert!(created.path.join(".env").exists());
    }

    #[test]
    fn create_rolls_back_when_a_post_add_step_fails() {
        use crate::git::cli::{GitCli, GitOutput};
        struct FailConfig(RealGit);
        impl GitCli for FailConfig {
            fn run_raw(&self, repo: &Path, args: &[&str]) -> Result<GitOutput> {
                if args.first() == Some(&"config") && args.iter().any(|a| a.starts_with("wt.")) {
                    return Ok(GitOutput {
                        success: false,
                        stdout: String::new(),
                        stderr: "simulated failure".into(),
                    });
                }
                self.0.run_raw(repo, args)
            }
        }
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let err = ws
            .create(
                &FailConfig(RealGit),
                &RealHookRunner,
                &create_opts("rollme"),
            )
            .unwrap_err();
        assert!(err.to_string().contains("simulated failure"));
        assert!(repo.git(&["branch", "--list", "rollme"]).trim().is_empty());
        assert!(!repo.git(&["worktree", "list"]).contains("rollme"));
    }

    /// Finds the row for `branch` in a fresh enriched listing.
    fn row_for(ws: &Workspace, branch: &str) -> Worktree {
        ws.list(&RealGit)
            .unwrap()
            .into_iter()
            .find(|w| w.branch.as_deref() == Some(branch))
            .unwrap()
    }

    #[test]
    fn list_enumerate_and_meta_expose_worktrees() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        ws.create(&RealGit, &RealHookRunner, &create_opts("feature/x"))
            .unwrap();
        let shallow = ws.enumerate(&RealGit).unwrap();
        assert_eq!(shallow.len(), 2);
        // The shallow pass has no status; the enriched pass does.
        assert!(shallow.iter().all(|w| w.dirty.is_none()));
        let feat = row_for(&ws, "feature/x");
        assert_eq!(feat.dirty, Some(false));
        assert_eq!(feat.base_ref.as_deref(), Some("main"));
    }

    #[test]
    fn write_meta_applies_only_the_set_fields() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        ws.create(&RealGit, &RealHookRunner, &create_opts("feature/x"))
            .unwrap();
        ws.write_meta(
            &RealGit,
            "feature/x",
            &MetaUpdate {
                pr_number: Some(7),
                pr_state: Some("open".into()),
                pr_title: Some("Add x".into()),
                pr_url: Some("https://example.test/7".into()),
                ..MetaUpdate::default()
            },
        )
        .unwrap();
        let meta = ws.read_meta("feature/x").unwrap();
        assert_eq!(meta.pr_number, Some(7));
        assert_eq!(meta.pr_state.as_deref(), Some("open"));
        assert_eq!(meta.pr_title.as_deref(), Some("Add x"));
        assert_eq!(meta.pr_url.as_deref(), Some("https://example.test/7"));
        // The keys `create` recorded survive an update that does not name them.
        assert_eq!(meta.base_ref.as_deref(), Some("main"));
        assert!(meta.created_by_wt);

        // A narrower update refreshes one key and leaves the rest.
        ws.write_meta(
            &RealGit,
            "feature/x",
            &MetaUpdate {
                pr_state: Some("merged".into()),
                ..MetaUpdate::default()
            },
        )
        .unwrap();
        let meta = ws.read_meta("feature/x").unwrap();
        assert_eq!(meta.pr_state.as_deref(), Some("merged"));
        assert_eq!(meta.pr_number, Some(7));
        assert_eq!(meta.pr_title.as_deref(), Some("Add x"));
    }

    #[test]
    fn write_meta_marks_created_by_wt_but_never_unmarks() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        repo.git(&["branch", "solo"]);
        // An empty update writes nothing at all.
        ws.write_meta(&RealGit, "solo", &MetaUpdate::default())
            .unwrap();
        assert_eq!(ws.read_meta("solo").unwrap(), WtMeta::default());

        ws.write_meta(
            &RealGit,
            "solo",
            &MetaUpdate {
                created_by_wt: true,
                ..MetaUpdate::default()
            },
        )
        .unwrap();
        assert!(ws.read_meta("solo").unwrap().created_by_wt);
        // `false` is "leave it alone", not "un-mark".
        ws.write_meta(&RealGit, "solo", &MetaUpdate::default())
            .unwrap();
        assert!(ws.read_meta("solo").unwrap().created_by_wt);
    }

    #[test]
    fn clear_meta_removes_the_section_and_tolerates_a_missing_one() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        ws.create(&RealGit, &RealHookRunner, &create_opts("feature/x"))
            .unwrap();
        assert!(ws.read_meta("feature/x").unwrap().created_by_wt);
        ws.clear_meta(&RealGit, "feature/x").unwrap();
        assert_eq!(ws.read_meta("feature/x").unwrap(), WtMeta::default());
        // Clearing a branch that never had metadata is not an error.
        ws.clear_meta(&RealGit, "never-recorded").unwrap();
    }

    #[test]
    fn metadata_writes_take_the_repo_lock() {
        // The bundle must not interleave with another writer (issue #99).
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        repo.git(&["branch", "locked"]);
        let held = ws.lock().unwrap();
        let err = ws
            .write_meta(
                &RealGit,
                "locked",
                &MetaUpdate {
                    pr_number: Some(1),
                    ..MetaUpdate::default()
                },
            )
            .unwrap_err();
        assert!(matches!(err, Error::LockUnavailable { .. }), "{err:?}");
        let err = ws.clear_meta(&RealGit, "locked").unwrap_err();
        assert!(matches!(err, Error::LockUnavailable { .. }), "{err:?}");
        drop(held);
        ws.clear_meta(&RealGit, "locked").unwrap();
    }

    #[test]
    fn metadata_writes_refuse_a_future_schema() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        repo.git(&["branch", "stamped"]);
        repo.git(&["config", "wt.schema", "3"]);
        let err = ws
            .write_meta(&RealGit, "stamped", &MetaUpdate::default())
            .unwrap_err();
        assert!(
            matches!(err, Error::SchemaTooNew { found: 3, .. }),
            "{err:?}"
        );
        let err = ws.clear_meta(&RealGit, "stamped").unwrap_err();
        assert!(
            matches!(err, Error::SchemaTooNew { found: 3, .. }),
            "{err:?}"
        );
    }

    #[test]
    fn remove_blocked_by_guards_is_a_typed_error() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        ws.create(&RealGit, &RealHookRunner, &create_opts("topic"))
            .unwrap();
        // No upstream -> unpushed; clean -> not dirty.
        let row = row_for(&ws, "topic");
        let err = ws
            .remove(
                &RealGit,
                &RealHookRunner,
                &row,
                &RemoveOptions {
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap_err();
        match err {
            Error::RemoveGuarded { dirty, unpushed } => {
                assert!(!dirty);
                assert!(unpushed);
            }
            other => panic!("expected RemoveGuarded, got {other:?}"),
        }
    }

    #[test]
    fn create_seeds_submodules_without_reaching_a_remote() {
        // The user-visible win. The fixture's submodule URL is a file path, and
        // git denies file-protocol submodule clones, so a worktree that had to
        // clone from the recorded URL would come up empty. Seeding populates it
        // from the repository's own object store instead, and the file-protocol
        // opt-in it needs for that is its own, scoped to the mirror path.
        let repo = TestRepo::init();
        repo.add_submodule("libs/sub");
        let ws = workspace(&repo);
        let created = ws
            .create(
                &RealGit,
                &RealHookRunner,
                &CreateOptions {
                    branch: "topic".to_string(),
                    init_submodules: true,
                    seed_submodules: true,
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap();

        assert!(
            created.path.join("libs/sub/sub.txt").exists(),
            "submodule was not populated"
        );
        assert_eq!(
            created.submodule_seeding.seeded,
            vec!["libs/sub".to_string()]
        );
        assert!(created.submodule_seeding.failed.is_empty());
        assert!(matches!(
            created.submodules,
            SubmodulesOutcome::Initialized(1)
        ));
    }

    #[test]
    fn reflink_materialization_matches_a_normal_checkout() {
        // The CoW path must be indistinguishable in result from a checkout: same
        // tracked content, clean status, same submodule state. Skipped where the
        // filesystem has no reflink support, since there is nothing to assert.
        let Some(repo) = TestRepo::init_cow() else {
            return;
        };
        repo.add_submodule("libs/sub");
        repo.write("tracked.txt", "content\n");
        repo.write(".gitignore", "build.out\n");
        repo.commit_all("add a tracked file and an ignore rule");
        // An ignored build artifact. Carrying these across is much of the point
        // of asking for a CoW clone, and because it is ignored the new worktree
        // is still clean.
        repo.write("build.out", "artifact\n");
        // Untracked work-in-progress, which belongs to the source worktree
        // alone. Copying it would hand the new worktree a dirty status it never
        // earned, and bypass the `copy` patterns that decide what travels.
        repo.write("scratch.txt", "unsaved\n");
        std::fs::create_dir_all(repo.root().join("wip")).unwrap();
        repo.write("wip/notes.md", "later\n");
        // A repository that hides untracked files from `git status` must not
        // thereby switch the protection off.
        repo.git(&["config", "status.showUntrackedFiles", "no"]);

        let ws = workspace(&repo);
        let created = ws
            .create(
                &RealGit,
                &RealHookRunner,
                &CreateOptions {
                    branch: "topic".to_string(),
                    init_submodules: true,
                    seed_submodules: true,
                    reflink: true,
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap();

        assert!(created.reflinked, "the CoW path did not run");
        // Tracked content is right and the worktree is clean.
        assert_eq!(
            std::fs::read_to_string(created.path.join("tracked.txt")).unwrap(),
            "content\n"
        );
        let status = repo.git(&["-C", &created.path.to_string_lossy(), "status", "--short"]);
        assert!(
            status.trim().is_empty(),
            "worktree is not clean: {status:?}"
        );
        // The submodule came across and is recognized, not left uninitialized.
        assert!(created.path.join("libs/sub/sub.txt").exists());
        let subs = repo.git(&[
            "-C",
            &created.path.to_string_lossy(),
            "submodule",
            "status",
            "--recursive",
        ]);
        assert!(
            subs.starts_with(' '),
            "submodule not in sync after a reflink create: {subs:?}"
        );
        // And it points at the real upstream. Attaching clones from the
        // repository's own mirror, so without the follow-up sync `origin` would
        // be `<repo>/.git/modules/libs/sub` and every later fetch or push in
        // this submodule would go to the primary worktree's object store.
        let origin =
            |dir: &Path| repo.git(&["-C", &dir.to_string_lossy(), "config", "remote.origin.url"]);
        assert_eq!(
            origin(&created.path.join("libs/sub")),
            origin(&repo.root().join("libs/sub")),
            "the reflinked submodule kept the local mirror as its origin"
        );
        // The ignored artifact rode along; the untracked work did not.
        assert!(created.path.join("build.out").exists());
        assert!(
            !created.path.join("scratch.txt").exists(),
            "an untracked source file was cloned into the new worktree"
        );
        assert!(
            !created.path.join("wip/notes.md").exists(),
            "an untracked source directory was cloned into the new worktree"
        );
    }

    #[test]
    fn reflink_declines_when_the_source_is_at_a_different_tree() {
        // Falling back must still produce a correct worktree, just not a cloned
        // one: the new branch is based on the *old* commit, whose tree differs
        // from the source worktree's current one.
        let repo = TestRepo::init();
        let base = repo.git(&["rev-parse", "HEAD"]).trim().to_string();
        repo.write("only-on-head.txt", "later\n");
        repo.commit_all("move the source ahead");

        let ws = workspace(&repo);
        let created = ws
            .create(
                &RealGit,
                &RealHookRunner,
                &CreateOptions {
                    branch: "topic".to_string(),
                    base: Some(base),
                    reflink: true,
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap();

        assert!(!created.reflinked, "cloned across differing trees");
        // The worktree still has the right content for its own base.
        assert!(!created.path.join("only-on-head.txt").exists());
        let status = repo.git(&["-C", &created.path.to_string_lossy(), "status", "--short"]);
        assert!(
            status.trim().is_empty(),
            "worktree is not clean: {status:?}"
        );
    }

    #[test]
    fn create_without_seeding_leaves_the_clone_to_git() {
        // The escape hatch. With seeding off, the same fixture falls back to a
        // real clone from the recorded file:// URL, which git denies — so the
        // submodule stays unpopulated and the failure is reported rather than
        // silently swallowed. This is exactly the behaviour before this feature.
        let repo = TestRepo::init();
        repo.add_submodule("libs/sub");
        let ws = workspace(&repo);
        let created = ws
            .create(
                &RealGit,
                &RealHookRunner,
                &CreateOptions {
                    branch: "topic".to_string(),
                    init_submodules: true,
                    seed_submodules: false,
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap();

        assert!(created.submodule_seeding.seeded.is_empty());
        assert!(!created.path.join("libs/sub/sub.txt").exists());
        assert!(matches!(
            created.submodules,
            SubmodulesOutcome::Failed { .. }
        ));
    }

    #[test]
    fn remove_succeeds_on_a_worktree_containing_submodules() {
        // `git worktree remove` refuses any worktree with a populated submodule
        // unless forced, so without the submodule-aware force this removal fails
        // with `fatal: working trees containing submodules cannot be moved or
        // removed` even though nothing is dirty.
        let repo = TestRepo::init();
        repo.add_submodule("libs/sub");
        let ws = workspace(&repo);
        let created = ws
            .create(&RealGit, &RealHookRunner, &create_opts("topic"))
            .unwrap();
        // Populate the submodule in the new worktree. A linked worktree does not
        // share `.git/modules`, so git clones from the recorded URL — which is a
        // file path here, and file-protocol submodule clones are denied by
        // default. The fixture opts in; production URLs do not need this.
        repo.git(&[
            "-C",
            &created.path.to_string_lossy(),
            "-c",
            "protocol.file.allow=always",
            "submodule",
            "update",
            "--init",
        ]);
        assert!(created.path.join("libs/sub/sub.txt").exists());
        // Clear the unpushed guard so the removal is not blocked for an
        // unrelated reason.
        give_upstream(&repo, "topic");

        let row = row_for(&ws, "topic");
        let removed = ws
            .remove(
                &RealGit,
                &RealHookRunner,
                &row,
                &RemoveOptions {
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap();
        assert!(!created.path.exists(), "worktree directory still present");
        assert!(
            removed.forced_for_submodules,
            "removal should record that git needed forcing for submodules"
        );
        assert!(
            !removed.forced_past_guards,
            "no wt guard was overridden, so this must not read as a forced removal"
        );
    }

    #[test]
    fn remove_guards_untracked_files_when_submodules_force_git() {
        // Forcing git past `working trees containing submodules cannot be
        // removed` also discards its refusal to delete untracked files, and
        // `remove.untracked_blocks` is off by default. Without the guard the
        // scratch file below would be deleted with nothing having checked.
        let repo = TestRepo::init();
        repo.add_submodule("libs/sub");
        let ws = workspace(&repo);
        let created = ws
            .create(&RealGit, &RealHookRunner, &create_opts("topic"))
            .unwrap();
        repo.git(&[
            "-C",
            &created.path.to_string_lossy(),
            "-c",
            "protocol.file.allow=always",
            "submodule",
            "update",
            "--init",
        ]);
        give_upstream(&repo, "topic");
        std::fs::write(created.path.join("scratch.txt"), "unsaved\n").unwrap();

        let row = row_for(&ws, "topic");
        let err = ws
            .remove(
                &RealGit,
                &RealHookRunner,
                &row,
                &RemoveOptions {
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap_err();
        assert!(matches!(err, Error::RemoveGuarded { dirty: true, .. }));
        assert!(created.path.join("scratch.txt").exists());

        // `--force` is still the way through, and still reports honestly.
        let row = row_for(&ws, "topic");
        let removed = ws
            .remove(
                &RealGit,
                &RealHookRunner,
                &row,
                &RemoveOptions {
                    no_hooks: true,
                    force_remove: true,
                    ..Default::default()
                },
            )
            .unwrap();
        assert!(!created.path.exists());
        assert!(removed.forced_past_guards);
    }

    #[test]
    fn remove_without_submodules_does_not_report_a_submodule_force() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        ws.create(&RealGit, &RealHookRunner, &create_opts("topic"))
            .unwrap();
        give_upstream(&repo, "topic");
        let row = row_for(&ws, "topic");
        let removed = ws
            .remove(
                &RealGit,
                &RealHookRunner,
                &row,
                &RemoveOptions {
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap();
        assert!(!removed.forced_for_submodules);
        assert!(!removed.forced_past_guards);
    }

    #[test]
    fn remove_force_reports_forced_past_guards() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        ws.create(&RealGit, &RealHookRunner, &create_opts("forced"))
            .unwrap();
        let row = row_for(&ws, "forced");
        let removed = ws
            .remove(
                &RealGit,
                &RealHookRunner,
                &row,
                &RemoveOptions {
                    force_remove: true,
                    force_branch: true,
                    no_hooks: true,
                    keep_branch: false,
                },
            )
            .unwrap();
        assert!(removed.forced_past_guards);
        assert!(!repo.git(&["worktree", "list"]).contains("forced"));
        // Merged wt-created branch is deleted per config.
        assert!(removed.branch_deleted);
        // Metadata is cleared.
        assert_eq!(ws.read_meta("forced").unwrap(), WtMeta::default());
    }

    #[test]
    fn remove_refuses_the_primary_worktree() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let main = row_for(&ws, "main");
        let err = ws
            .remove(&RealGit, &RealHookRunner, &main, &RemoveOptions::default())
            .unwrap_err();
        assert!(err.to_string().contains("primary"));
    }

    #[test]
    fn remove_missing_worktree_prunes_without_guards() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let created = ws
            .create(&RealGit, &RealHookRunner, &create_opts("gone"))
            .unwrap();
        std::fs::remove_dir_all(&created.path).unwrap();
        let row = row_for(&ws, "gone");
        assert!(row.is_missing);
        let removed = ws
            .remove(
                &RealGit,
                &RealHookRunner,
                &row,
                &RemoveOptions {
                    no_hooks: true,
                    ..Default::default()
                },
            )
            .unwrap();
        assert_eq!(removed.pre_remove, HookOutcome::Skipped);
        assert!(!repo.git(&["worktree", "list"]).contains("gone"));
    }

    #[test]
    fn remove_failing_pre_remove_hook_aborts_unless_forced() {
        let repo = TestRepo::init();
        repo.write(".wt.toml", "[hooks]\npre_remove = \"exit 5\"\n");
        repo.commit_all("config");
        let ws = workspace(&repo);
        ws.create(&RealGit, &RealHookRunner, &create_opts("hooked"))
            .unwrap();
        // Give the branch an upstream so guards do not block first.
        let head = repo.git(&["rev-parse", "HEAD"]).trim().to_string();
        repo.git(&["update-ref", "refs/remotes/origin/hooked", &head]);
        repo.git(&["config", "branch.hooked.remote", "origin"]);
        repo.git(&["config", "branch.hooked.merge", "refs/heads/hooked"]);
        let row = row_for(&ws, "hooked");
        let err = ws
            .remove(&RealGit, &RealHookRunner, &row, &RemoveOptions::default())
            .unwrap_err();
        assert!(
            err.to_string()
                .contains("pre_remove hook exited with status 5")
        );
        // Forced: the failure is downgraded to an outcome and removal proceeds.
        let removed = ws
            .remove(
                &RealGit,
                &RealHookRunner,
                &row,
                &RemoveOptions {
                    force_remove: true,
                    ..Default::default()
                },
            )
            .unwrap();
        assert_eq!(removed.pre_remove, HookOutcome::ExitedNonZero(5));
        assert!(!repo.git(&["worktree", "list"]).contains("hooked"));
    }

    #[test]
    fn discover_refuses_a_future_schema() {
        let repo = TestRepo::init();
        repo.git(&["config", "wt.schema", "99"]);
        let err = Workspace::discover(repo.root(), &env(), &RealGit)
            .err()
            .expect("a future schema must refuse discovery");
        assert!(matches!(err, Error::SchemaTooNew { found: 99, .. }));
    }

    #[test]
    fn mutations_refuse_a_schema_stamped_after_discovery() {
        // A long-lived Workspace must not mutate a repo that was upgraded
        // underneath it: create/remove re-check through a fresh handle.
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        repo.git(&["config", "wt.schema", "2"]);
        let err = ws
            .create(&RealGit, &RealHookRunner, &create_opts("late"))
            .unwrap_err();
        assert!(matches!(err, Error::SchemaTooNew { found: 2, .. }));
    }

    #[test]
    fn lock_is_exclusive_and_released_on_drop() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let held = ws.lock().unwrap();
        // A second acquisition times out while the first is held...
        let err = acquire_repo_lock(ws.root(), Duration::from_millis(50))
            .err()
            .expect("the held lock must exclude a second holder");
        match &err {
            Error::LockUnavailable { path, .. } => {
                assert!(path.ends_with("wt-mutation.lock"), "{path}");
            }
            other => panic!("expected LockUnavailable, got {other:?}"),
        }
        // ...and succeeds once the holder is dropped.
        drop(held);
        acquire_repo_lock(ws.root(), Duration::from_millis(50)).unwrap();
    }

    #[test]
    fn a_schema_refusal_does_not_strand_the_lock() {
        // The schema gate runs with the lock held (issue #106), so its refusal
        // has to give the lock back on the way out — otherwise one stamped
        // repository would wedge every later mutation for the full timeout.
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        repo.git(&["config", "wt.schema", "2"]);
        let err = acquire_repo_lock(ws.root(), Duration::from_millis(50))
            .err()
            .expect("a future schema must refuse the acquisition");
        assert!(
            matches!(err, Error::SchemaTooNew { found: 2, .. }),
            "{err:?}"
        );
        assert!(!ws.root().join(".git/wt-mutation.lock").exists());

        repo.git(&["config", "--unset", "wt.schema"]);
        acquire_repo_lock(ws.root(), Duration::from_millis(50)).unwrap();
    }

    #[test]
    fn the_lock_gate_reads_a_bare_repository_too() {
        // The gate re-opens the repository from the lock root (issue #106), and
        // for a bare primary that root *is* the git directory rather than a
        // worktree containing one — so acquisition must not depend on a
        // workdir. `wt` supports bare primaries, so this is a real shape.
        let repo = TestRepo::init_bare();
        acquire_repo_lock(repo.root(), Duration::from_millis(50)).unwrap();

        repo.git(&["config", "wt.schema", "2"]);
        let err = acquire_repo_lock(repo.root(), Duration::from_millis(50))
            .err()
            .expect("a bare repository is gated like any other");
        assert!(
            matches!(err, Error::SchemaTooNew { found: 2, .. }),
            "{err:?}"
        );
    }

    #[test]
    fn a_schema_bump_landing_during_the_lock_wait_is_refused() {
        // The window issue #106 is about: a writer that passed the schema gate
        // and then blocked on the lock must not mutate against the version it
        // finally holds the lock over. Ordering is forced, not slept on — the
        // writer signals once it has a Workspace, and this thread holds the
        // lock across the bump, so the writer can only reach the mutation
        // after `wt.schema` is already 2.
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        repo.git(&["branch", "stamped"]);
        let held = ws.lock().unwrap();

        let (discovered, wait) = std::sync::mpsc::channel();
        let root = repo.root().to_path_buf();
        let writer = std::thread::spawn(move || {
            let ws = Workspace::discover(&root, &env(), &RealGit)?;
            discovered.send(()).expect("the test thread outlives this");
            ws.write_meta(
                &RealGit,
                "stamped",
                &MetaUpdate {
                    pr_number: Some(1),
                    ..MetaUpdate::default()
                },
            )
        });

        wait.recv().expect("the writer discovers before it blocks");
        repo.git(&["config", "wt.schema", "2"]);
        drop(held);

        let err = writer
            .join()
            .expect("the writer must not panic")
            .expect_err("the bumped schema must refuse the blocked write");
        assert!(
            matches!(err, Error::SchemaTooNew { found: 2, .. }),
            "{err:?}"
        );
        // The refusal is total: nothing was written on the way to it.
        repo.git(&["config", "--unset", "wt.schema"]);
        assert_eq!(ws.read_meta("stamped").unwrap(), WtMeta::default());
    }

    #[test]
    fn create_releases_the_lock_before_the_post_create_hook() {
        // A hook that re-enters wt must not deadlock (issue #99): the hook
        // itself proves the lock file is gone by the time it runs.
        let repo = TestRepo::init();
        repo.write(
            ".wt.toml",
            "[hooks]\npost_create = \"test ! -e \\\"$WT_REPO_ROOT/.git/wt-mutation.lock\\\"\"\n",
        );
        repo.commit_all("config");
        let ws = workspace(&repo);
        let mut opts = create_opts("hookfree");
        opts.no_hooks = false;
        let created = ws.create(&RealGit, &RealHookRunner, &opts).unwrap();
        assert_eq!(created.post_create, HookOutcome::Succeeded);
    }

    #[test]
    fn concurrent_creates_on_one_branch_do_not_corrupt_metadata() {
        // Two writers race to create the same branch (issue #99): exactly one
        // wins, the loser gets a clean error, and the metadata ends up
        // consistent — one worktree, one baseRef, createdByWt set once.
        let repo = TestRepo::init();
        let root = repo.root().to_path_buf();
        let spawn = |root: PathBuf| {
            std::thread::spawn(move || {
                let ws = Workspace::discover(&root, &env(), &RealGit)?;
                ws.create(&RealGit, &RealHookRunner, &create_opts("feat/race"))
            })
        };
        let a = spawn(root.clone());
        let b = spawn(root);
        let results = [a.join().unwrap(), b.join().unwrap()];
        let ok = results.iter().filter(|r| r.is_ok()).count();
        // Both may succeed only if one reused the other's finished worktree;
        // never may both claim to have created it.
        let created = results
            .iter()
            .filter(|r| r.as_ref().is_ok_and(|c| !c.reused))
            .count();
        assert!(ok >= 1, "at least one racer must win: {results:?}");
        assert_eq!(created, 1, "exactly one racer creates: {results:?}");

        let ws = workspace(&repo);
        let rows = ws.list(&RealGit).unwrap();
        let race_rows: Vec<_> = rows
            .iter()
            .filter(|w| w.branch.as_deref() == Some("feat/race"))
            .collect();
        assert_eq!(race_rows.len(), 1);
        let meta = ws.read_meta("feat/race").unwrap();
        assert_eq!(meta.base_ref.as_deref(), Some("main"));
        assert!(meta.created_by_wt);
    }

    #[test]
    fn resolve_base_falls_back_to_head_only_without_default() {
        let repo = TestRepo::init();
        let ws = workspace(&repo);
        let r = Repo::discover(repo.root()).unwrap();
        assert_eq!(
            resolve_base(&r, ws.config(), Some("explicit")),
            ("explicit".into(), false)
        );
        // The repo default branch resolves without a HEAD fallback.
        assert_eq!(resolve_base(&r, ws.config(), None), ("main".into(), false));
        // A configured default_base wins over the repo default branch.
        let mut config = ws.config().clone();
        config.default_base = Some("trunk".into());
        assert_eq!(resolve_base(&r, &config, None), ("trunk".into(), false));
    }
}