synaps 0.1.0

//! Post-install setup-script execution.
//!
//! When a plugin manifest declares a setup script, the marketplace
//! install flow auto-runs it after the plugin's source is in place.
//! This is how source-shipped plugins (e.g. ones that ship a Rust
//! crate and need `cargo build --release` to produce the binary
//! [`extension.command`] points at) get built without forcing the
//! user to run `scripts/setup.sh` by hand.
//!
//! Two manifest slots are recognised, in priority order:
//!
//! 1. `extension.setup` — the extension's own build script. Checked
//!    first because the extension binary is what the host will spawn
//!    immediately on session start.
//! 2. `provides.sidecar.setup` — the sidecar's build script (legacy
//!    slot; still honoured for sidecar-only plugins).
//!
//! At most one script runs per install. Plugins that ship both an
//! extension and a sidecar from one repo should drive both builds
//! from a single `scripts/setup.sh` referenced via `extension.setup`.
//!
//! ## Security
//!
//! Setup scripts are arbitrary shell. We mitigate by:
//! - Refusing setup paths that escape the plugin dir (`..`, absolute).
//! - Refusing setup paths that don't resolve (canonicalize) inside the
//!   plugin dir.
//! - Requiring the script file exists and is executable.
//! - Capping wall-clock runtime at [`SETUP_TIMEOUT`].
//! - Capturing stdout+stderr to a per-install log (no swallowing).
//!
//! ## Failure mode
//!
//! A failed setup script does **not** roll back the install — the
//! source is on disk and the user can rerun the script manually. The
//! caller surfaces the failure to the UI with a pointer to the log
//! file.
//!
//! Pure helpers live here so they can be unit-tested without a real
//! tokio runtime; the async runner is a thin shell over
//! `tokio::process::Command`.

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

use crate::skills::manifest::PluginManifest;

/// Stable host-triple string used as the lookup key in
/// [`crate::extensions::manifest::ExtensionManifest::prebuilt`]. We
/// intentionally use a compact `<os>-<arch>` form (e.g.
/// `linux-x86_64`, `darwin-arm64`, `windows-x86_64`) rather than full
/// Rust target triples (`x86_64-unknown-linux-gnu`) because plugin
/// authors hand-write these strings into JSON manifests — readability
/// > pedantry.
///
/// Returns `None` for hosts we don't have a stable name for (caller
/// then skips the prebuilt-fallback path and falls back to the setup
/// script).

/// Maximum accepted prebuilt archive size (128 MiB). Downloads are streamed and
/// rejected before extraction if this cap is exceeded.
pub const MAX_PREBUILT_ARCHIVE_BYTES: u64 = 128 * 1024 * 1024;

const PREBUILT_CONNECT_TIMEOUT: Duration = Duration::from_secs(15);
const PREBUILT_REQUEST_TIMEOUT: Duration = Duration::from_secs(120);

/// Sanitize a manifest-controlled string before using it as a filename fragment
/// or displaying it in terse user-facing hints. Unsafe/control characters become
/// `_`; empty/all-unsafe input becomes `plugin`.
pub fn safe_name_fragment(input: &str) -> String {
    let mut out = String::with_capacity(input.len().min(80));
    for ch in input.chars().take(80) {
        if ch.is_ascii_alphanumeric() || matches!(ch, '-' | '_' | '.') {
            out.push(ch);
        } else {
            out.push('_');
        }
    }
    let trimmed = out.trim_matches('.').trim_matches('_').to_string();
    if trimmed.is_empty() || trimmed == ".." {
        "plugin".to_string()
    } else {
        trimmed
    }
}

/// Normalize SHA-256 manifest values to lower-case hex. Rejects anything other
/// than exactly 64 ASCII hex characters.
pub fn normalize_sha256(value: &str) -> Option<String> {
    let trimmed = value.trim();
    if trimmed.len() == 64 && trimmed.bytes().all(|b| b.is_ascii_hexdigit()) {
        Some(trimmed.to_ascii_lowercase())
    } else {
        None
    }
}

fn prebuilt_url_allowed(url: &str) -> bool {
    if url.starts_with("https://") {
        return true;
    }
    #[cfg(test)]
    {
        if url.starts_with("file://") {
            return true;
        }
    }
    false
}

fn archive_suffix(url_for_suffix: &str) -> Result<&'static str, PrebuiltError> {
    let url_clean = url_for_suffix
        .split(['?', '#'])
        .next()
        .unwrap_or(url_for_suffix)
        .to_ascii_lowercase();
    if url_clean.ends_with(".tar.gz") || url_clean.ends_with(".tgz") {
        Ok("tar.gz")
    } else if url_clean.ends_with(".zip") {
        Ok("zip")
    } else if url_clean.ends_with(".tar.xz") || url_clean.ends_with(".tar.bz2") {
        Err(PrebuiltError::UnsupportedArchive {
            url: format!("{url_for_suffix} (xz/bz2 prebuilt archives are not supported by the hardened extractor; use .tar.gz or .zip)"),
        })
    } else {
        Err(PrebuiltError::UnsupportedArchive {
            url: url_for_suffix.to_string(),
        })
    }
}

fn validate_archive_relative_path(path: &Path) -> Result<(), PrebuiltError> {
    if path.is_absolute() {
        return Err(PrebuiltError::Extract(format!(
            "archive entry '{}' is absolute",
            path.display()
        )));
    }
    if path.components().any(|c| matches!(c, Component::ParentDir | Component::Prefix(_))) {
        return Err(PrebuiltError::Extract(format!(
            "archive entry '{}' escapes extraction directory",
            path.display()
        )));
    }
    Ok(())
}

fn copy_dir_contents(src: &Path, dest: &Path) -> std::io::Result<()> {
    for entry in std::fs::read_dir(src)? {
        let entry = entry?;
        let from = entry.path();
        let to = dest.join(entry.file_name());
        let meta = entry.file_type()?;
        if meta.is_dir() {
            std::fs::create_dir_all(&to)?;
            copy_dir_contents(&from, &to)?;
        } else if meta.is_file() {
            if let Some(parent) = to.parent() {
                std::fs::create_dir_all(parent)?;
            }
            std::fs::copy(&from, &to)?;
            #[cfg(unix)]
            {
                use std::os::unix::fs::PermissionsExt;
                let mode = std::fs::metadata(&from)?.permissions().mode();
                std::fs::set_permissions(&to, std::fs::Permissions::from_mode(mode))?;
            }
        }
    }
    Ok(())
}

pub fn host_triple() -> Option<&'static str> {
    let os = if cfg!(target_os = "linux") {
        "linux"
    } else if cfg!(target_os = "macos") {
        "darwin"
    } else if cfg!(target_os = "windows") {
        "windows"
    } else {
        return None;
    };
    let arch = if cfg!(target_arch = "x86_64") {
        "x86_64"
    } else if cfg!(target_arch = "aarch64") {
        "arm64"
    } else {
        return None;
    };
    // Use a small static table so the returned slice is `'static`.
    Some(match (os, arch) {
        ("linux", "x86_64") => "linux-x86_64",
        ("linux", "arm64") => "linux-arm64",
        ("darwin", "x86_64") => "darwin-x86_64",
        ("darwin", "arm64") => "darwin-arm64",
        ("windows", "x86_64") => "windows-x86_64",
        ("windows", "arm64") => "windows-arm64",
        _ => return None,
    })
}

/// Wall-clock cap on a single setup script. Sample from-scratch
/// builds run ~5 minutes on a modern dev box; 10 minutes leaves a
/// healthy margin for slower CI/older hardware without making a
/// runaway script wedge the install flow forever.
pub const SETUP_TIMEOUT: Duration = Duration::from_secs(600);

/// Outcome of a successful setup-script run.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct SetupOutcome {
    /// Path to the log file containing combined stdout+stderr.
    pub log_path: PathBuf,
    /// Process exit status (always 0 on the success path).
    pub exit_code: i32,
}

/// Why a setup script could not be run, or why it failed once started.
#[derive(Debug, thiserror::Error)]
pub enum SetupError {
    /// Manifest declared a setup path but it points outside the plugin
    /// directory or contains a `..` component.
    #[error("setup script path '{path}' escapes plugin directory")]
    EscapesPluginDir { path: String },

    /// Manifest declared a setup path that doesn't exist on disk after
    /// canonicalization.
    #[error("setup script '{path}' not found in plugin directory")]
    NotFound { path: String },

    /// Setup ran but exited non-zero. `log_path` points at captured
    /// stdout+stderr; UI should surface it to the user.
    #[error("setup script exited with code {exit_code}; see {}", log_path.display())]
    NonZeroExit { exit_code: i32, log_path: PathBuf },

    /// Setup exceeded [`SETUP_TIMEOUT`] and was killed.
    #[error("setup script timed out after {secs}s; see {}", log_path.display())]
    Timeout { secs: u64, log_path: PathBuf },

    /// I/O error setting up the log file or spawning the process.
    #[error("setup script io: {0}")]
    Io(#[from] std::io::Error),
}

/// Why an extension command verification failed. Distinct from
/// [`SetupError`] because the failure mode and remediation are
/// different — here, the build "succeeded" but the artifact the
/// manifest promised isn't there.
#[derive(Debug, thiserror::Error, PartialEq, Eq)]
pub enum CommandVerifyError {
    /// `extension.command` resolves to a relative path that escapes the
    /// plugin directory (`..` traversal or symlink that points outside).
    #[error("extension command path '{path}' escapes plugin directory")]
    EscapesPluginDir { path: String },

    /// The resolved path doesn't exist on disk. Most common cause:
    /// setup script ran, exited 0, but didn't actually produce the
    /// declared binary.
    #[error("extension command '{path}' does not exist (resolved to {})", resolved.display())]
    Missing { path: String, resolved: PathBuf },

    /// The path exists but isn't executable (Unix only — Windows skips
    /// this check). Common cause: build artifact missing the +x bit
    /// after extraction from a source archive.
    #[cfg(unix)]
    #[error("extension command '{path}' exists but is not executable (mode {mode:o})")]
    NotExecutable { path: String, mode: u32 },

    /// The path resolves to a directory, not a file.
    #[error("extension command '{path}' is a directory, not a file")]
    NotAFile { path: String },
}

/// Verify that the extension binary declared by
/// [`crate::extensions::manifest::ExtensionManifest::command`] actually
/// exists and is executable inside `plugin_dir`. Used as the
/// post-condition check after [`run_setup_script`] succeeds, so a
/// build script that exits 0 but doesn't produce the promised binary
/// surfaces a clear error instead of silently breaking spawn at
/// runtime.
///
/// Mirrors the host-side resolution rules in
/// [`crate::extensions::manager`] except absolute plugin extension commands are
/// rejected: shipped extension binaries must be plugin-relative.
/// - `command` is **absolute**: reject
/// - `command` is **bare** (no path separator): skip — it's a PATH
///   lookup, not a plugin-shipped artifact
/// - `command` is **relative with separators**: join with `plugin_dir`,
///   canonicalize, ensure it stays inside `plugin_dir`, then verify
///
/// Returns `Ok(None)` when the manifest declares no extension or the
/// command is a bare PATH lookup (nothing to verify).
/// Returns `Ok(Some(resolved_path))` on successful verification.
pub fn verify_extension_command(
    manifest: &PluginManifest,
    plugin_dir: &Path,
) -> Result<Option<PathBuf>, CommandVerifyError> {
    let Some(ext) = manifest.extension.as_ref() else {
        return Ok(None);
    };
    let cmd = &ext.command;
    let cmd_path = Path::new(cmd);

    // Bare command name (e.g. "python3") — defer to PATH at spawn time.
    if !cmd.contains(std::path::MAIN_SEPARATOR) && !cmd.contains('/') {
        return Ok(None);
    }

    let resolved = if cmd_path.is_absolute() {
        return Err(CommandVerifyError::EscapesPluginDir { path: cmd.clone() });
    } else {
        // Reject `..` traversal up front (don't rely on canonicalize).
        if cmd_path
            .components()
            .any(|c| matches!(c, std::path::Component::ParentDir))
        {
            return Err(CommandVerifyError::EscapesPluginDir { path: cmd.clone() });
        }
        let joined = plugin_dir.join(cmd_path);
        match joined.canonicalize() {
            Ok(p) => {
                let canonical_dir = plugin_dir
                    .canonicalize()
                    .unwrap_or_else(|_| plugin_dir.to_path_buf());
                if !p.starts_with(&canonical_dir) {
                    return Err(CommandVerifyError::EscapesPluginDir { path: cmd.clone() });
                }
                p
            }
            Err(_) => {
                return Err(CommandVerifyError::Missing {
                    path: cmd.clone(),
                    resolved: joined,
                });
            }
        }
    };

    if !resolved.exists() {
        return Err(CommandVerifyError::Missing {
            path: cmd.clone(),
            resolved,
        });
    }
    let meta = std::fs::metadata(&resolved).map_err(|_| CommandVerifyError::Missing {
        path: cmd.clone(),
        resolved: resolved.clone(),
    })?;
    if meta.is_dir() {
        return Err(CommandVerifyError::NotAFile { path: cmd.clone() });
    }
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        let mode = meta.permissions().mode();
        // Any execute bit is enough — owner/group/other.
        if mode & 0o111 == 0 {
            return Err(CommandVerifyError::NotExecutable {
                path: cmd.clone(),
                mode,
            });
        }
    }
    Ok(Some(resolved))
}

/// Why a prebuilt-binary install attempt failed. Variants distinguish
/// "no asset for this host" (caller falls back to the setup script)
/// from "asset matched but couldn't be installed" (caller surfaces
/// the error — security failures and network issues should not
/// silently trigger a build).
#[derive(Debug, thiserror::Error)]
pub enum PrebuiltError {
    /// Host triple has no entry in `extension.prebuilt`. Caller should
    /// fall back to the setup script. Not really an error — just a
    /// signal that there's nothing to try.
    #[error("no prebuilt asset declared for this host")]
    NoMatchingAsset,

    /// Network / HTTP problem fetching the URL.
    #[error("download failed: {0}")]
    Download(String),

    /// Downloaded bytes don't match the declared SHA-256. Treated as a
    /// hard failure (don't fall back to setup) since this could
    /// indicate tampering, mirror corruption, or a stale manifest.
    #[error("checksum mismatch: expected {expected}, got {actual}")]
    ChecksumMismatch { expected: String, actual: String },

    /// `tar` / `unzip` exited non-zero or wasn't on PATH.
    #[error("archive extraction failed: {0}")]
    Extract(String),

    /// The archive doesn't end in a recognized suffix (we support
    /// `.tar.gz` / `.tgz` / `.tar.xz` / `.tar.bz2` / `.zip`).
    #[error("unsupported archive type for url '{url}'")]
    UnsupportedArchive { url: String },

    /// Asset URL must be `https://` (or `file://` in tests).
    #[error("refusing non-https prebuilt url '{url}'")]
    UnsafeUrl { url: String },

    /// Manifest checksum is not exactly 64 hex characters.
    #[error("invalid sha256 '{sha256}'; expected exactly 64 hex characters")]
    InvalidSha256 { sha256: String },

    /// Prebuilt response or stream exceeded the configured size cap.
    #[error("prebuilt archive exceeds maximum size of {max} bytes")]
    TooLarge { max: u64 },

    /// I/O setting up the temp file or moving extracted artifacts.
    #[error("io: {0}")]
    Io(#[from] std::io::Error),

    /// Asset extracted but the manifest's `extension.command` still
    /// doesn't resolve. The archive layout is wrong.
    #[error("prebuilt extracted but extension command not found: {0}")]
    Verify(#[from] CommandVerifyError),
}

/// Lower-case hex encode of arbitrary bytes. Inlined to avoid pulling
/// in a `hex` crate just for this one site.
fn hex_encode_lower(bytes: &[u8]) -> String {
    let mut out = String::with_capacity(bytes.len() * 2);
    for b in bytes {
        out.push(char::from_digit((*b >> 4) as u32, 16).unwrap());
        out.push(char::from_digit((*b & 0x0f) as u32, 16).unwrap());
    }
    out
}

/// Try to install the extension binary from
/// [`crate::extensions::manifest::ExtensionManifest::prebuilt`] for
/// the current host. Lookup is by [`host_triple`].
///
/// On success: downloads the URL, verifies the SHA-256, extracts
/// the archive into `plugin_dir`, then runs
/// [`verify_extension_command`] to confirm the layout was correct.
/// Returns `Ok(Some(path))` pointing at the resolved binary.
///
/// On `Err(PrebuiltError::NoMatchingAsset)`: no entry for this host
/// — caller should fall back to the setup script.
///
/// On any other `Err`: surface to the user; do **not** silently fall
/// back to the setup script (a checksum failure could mean tampering;
/// a network failure means the user wanted prebuilt and should know).
pub async fn try_install_from_prebuilt(
    manifest: &PluginManifest,
    plugin_dir: &Path,
) -> Result<PathBuf, PrebuiltError> {
    let Some(ext) = manifest.extension.as_ref() else {
        return Err(PrebuiltError::NoMatchingAsset);
    };
    let Some(triple) = host_triple() else {
        return Err(PrebuiltError::NoMatchingAsset);
    };
    let Some(asset) = ext.prebuilt.get(triple) else {
        return Err(PrebuiltError::NoMatchingAsset);
    };

    if !prebuilt_url_allowed(&asset.url) {
        return Err(PrebuiltError::UnsafeUrl {
            url: asset.url.clone(),
        });
    }
    let expected_sha = normalize_sha256(&asset.sha256).ok_or_else(|| PrebuiltError::InvalidSha256 {
        sha256: asset.sha256.clone(),
    })?;

    let tmp_archive = plugin_dir.join(format!(".prebuilt-{triple}-download"));
    match std::fs::remove_file(&tmp_archive) {
        Ok(()) => {}
        Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
        Err(e) => return Err(PrebuiltError::Io(e)),
    }

    let download_res = download_prebuilt_to_file(&asset.url, &tmp_archive, MAX_PREBUILT_ARCHIVE_BYTES).await;
    let actual = match download_res {
        Ok(sha) => sha,
        Err(e) => {
            let _ = std::fs::remove_file(&tmp_archive);
            return Err(e);
        }
    };
    if actual != expected_sha {
        let _ = std::fs::remove_file(&tmp_archive);
        return Err(PrebuiltError::ChecksumMismatch {
            expected: expected_sha,
            actual,
        });
    }

    let archive = tmp_archive.clone();
    let dest = plugin_dir.to_path_buf();
    let url = asset.url.clone();
    let extract_res = tokio::task::spawn_blocking(move || extract_archive(&archive, &dest, &url))
        .await
        .map_err(|e| PrebuiltError::Extract(format!("extract task join error: {e}")))?;
    let _ = std::fs::remove_file(&tmp_archive);
    extract_res?;

    // Post-condition: the binary the manifest promised must now resolve.
    let resolved = verify_extension_command(manifest, plugin_dir)?
        .ok_or_else(|| {
            PrebuiltError::Verify(CommandVerifyError::Missing {
                path: ext.command.clone(),
                resolved: plugin_dir.join(&ext.command),
            })
        })?;
    Ok(resolved)
}

async fn download_prebuilt_to_file(
    url: &str,
    tmp_archive: &Path,
    max_bytes: u64,
) -> Result<String, PrebuiltError> {
    use sha2::{Digest, Sha256};

    let mut hasher = Sha256::new();
    let mut written: u64 = 0;

    if let Some(path) = url.strip_prefix("file://") {
        #[cfg(not(test))]
        {
            let _ = path;
            return Err(PrebuiltError::UnsafeUrl { url: url.to_string() });
        }
        #[cfg(test)]
        {
            let mut input = std::fs::File::open(path)
                .map_err(|e| PrebuiltError::Download(format!("file read {path}: {e}")))?;
            let mut output = std::fs::File::create(tmp_archive)?;
            let mut buf = [0u8; 8192];
            loop {
                let n = std::io::Read::read(&mut input, &mut buf)
                    .map_err(|e| PrebuiltError::Download(format!("file read {path}: {e}")))?;
                if n == 0 {
                    break;
                }
                written += n as u64;
                if written > max_bytes {
                    return Err(PrebuiltError::TooLarge { max: max_bytes });
                }
                hasher.update(&buf[..n]);
                std::io::Write::write_all(&mut output, &buf[..n])?;
            }
            return Ok(hex_encode_lower(&hasher.finalize()));
        }
    }

    let client = reqwest::Client::builder()
        .connect_timeout(PREBUILT_CONNECT_TIMEOUT)
        .timeout(PREBUILT_REQUEST_TIMEOUT)
        .build()
        .map_err(|e| PrebuiltError::Download(e.to_string()))?;
    let mut response = client
        .get(url)
        .send()
        .await
        .map_err(|e| PrebuiltError::Download(e.to_string()))?;
    if !response.status().is_success() {
        return Err(PrebuiltError::Download(format!("HTTP {}", response.status())));
    }
    if let Some(len) = response.content_length() {
        if len > max_bytes {
            return Err(PrebuiltError::TooLarge { max: max_bytes });
        }
    }

    let mut output = tokio::fs::File::create(tmp_archive).await?;
    while let Some(chunk) = response
        .chunk()
        .await
        .map_err(|e| PrebuiltError::Download(e.to_string()))?
    {
        written += chunk.len() as u64;
        if written > max_bytes {
            return Err(PrebuiltError::TooLarge { max: max_bytes });
        }
        hasher.update(&chunk);
        tokio::io::AsyncWriteExt::write_all(&mut output, &chunk).await?;
    }
    tokio::io::AsyncWriteExt::flush(&mut output).await?;
    Ok(hex_encode_lower(&hasher.finalize()))
}

/// Extract a prebuilt archive into a sandbox temp directory, validate entry
/// paths, then copy validated contents into `dest_dir`. The hardened extractor
/// supports `.tar.gz`/`.tgz` and `.zip`; xz/bz2 are rejected until a native
/// decoder is added.
fn extract_archive(
    archive: &Path,
    dest_dir: &Path,
    url_for_suffix: &str,
) -> Result<(), PrebuiltError> {
    let kind = archive_suffix(url_for_suffix)?;
    let extract_root = dest_dir.join(format!(
        ".prebuilt-extract-{}",
        chrono::Utc::now().timestamp_nanos_opt().unwrap_or_default()
    ));
    match std::fs::remove_dir_all(&extract_root) {
        Ok(()) => {}
        Err(e) if e.kind() == std::io::ErrorKind::NotFound => {}
        Err(e) => return Err(PrebuiltError::Io(e)),
    }
    std::fs::create_dir_all(&extract_root)?;
    let result = match kind {
        "tar.gz" => extract_tar_gz_safe(archive, &extract_root),
        "zip" => extract_zip_safe(archive, &extract_root),
        _ => unreachable!(),
    }
    .and_then(|_| copy_dir_contents(&extract_root, dest_dir).map_err(PrebuiltError::Io));
    let cleanup = std::fs::remove_dir_all(&extract_root);
    match (result, cleanup) {
        (Ok(()), Ok(())) => Ok(()),
        (Ok(()), Err(e)) => Err(PrebuiltError::Extract(format!(
            "failed to clean extraction directory {}: {e}",
            extract_root.display()
        ))),
        (Err(e), _) => Err(e),
    }
}

fn extract_tar_gz_safe(archive: &Path, root: &Path) -> Result<(), PrebuiltError> {
    use std::process::{Command, Stdio};

    let list = Command::new("tar")
        .arg("-tzf")
        .arg(archive)
        .output()
        .map_err(|e| PrebuiltError::Extract(format!("spawn tar: {e}")))?;
    if !list.status.success() {
        return Err(PrebuiltError::Extract(format!(
            "tar list exited {}: {}",
            list.status,
            String::from_utf8_lossy(&list.stderr).trim()
        )));
    }
    for line in String::from_utf8_lossy(&list.stdout).lines() {
        validate_archive_relative_path(Path::new(line))?;
    }
    let out = Command::new("tar")
        .arg("--no-same-owner")
        .arg("--no-same-permissions")
        .arg("-xzf")
        .arg(archive)
        .arg("-C")
        .arg(root)
        .stdin(Stdio::null())
        .output()
        .map_err(|e| PrebuiltError::Extract(format!("spawn tar: {e}")))?;
    if !out.status.success() {
        return Err(PrebuiltError::Extract(format!(
            "tar exited {}: {}",
            out.status,
            String::from_utf8_lossy(&out.stderr).trim()
        )));
    }
    validate_extracted_tree(root)
}

fn extract_zip_safe(archive: &Path, root: &Path) -> Result<(), PrebuiltError> {
    use std::process::{Command, Stdio};

    let list = Command::new("unzip")
        .arg("-Z1")
        .arg(archive)
        .output()
        .map_err(|e| PrebuiltError::Extract(format!("spawn unzip: {e}")))?;
    if !list.status.success() {
        return Err(PrebuiltError::Extract(format!(
            "unzip list exited {}: {}",
            list.status,
            String::from_utf8_lossy(&list.stderr).trim()
        )));
    }
    for line in String::from_utf8_lossy(&list.stdout).lines() {
        validate_archive_relative_path(Path::new(line))?;
    }
    let out = Command::new("unzip")
        .arg("-q")
        .arg(archive)
        .arg("-d")
        .arg(root)
        .stdin(Stdio::null())
        .output()
        .map_err(|e| PrebuiltError::Extract(format!("spawn unzip: {e}")))?;
    if !out.status.success() {
        return Err(PrebuiltError::Extract(format!(
            "unzip exited {}: {}",
            out.status,
            String::from_utf8_lossy(&out.stderr).trim()
        )));
    }
    validate_extracted_tree(root)
}

fn validate_extracted_tree(root: &Path) -> Result<(), PrebuiltError> {
    let canonical_root = root.canonicalize()?;
    fn walk(path: &Path, root: &Path) -> Result<(), PrebuiltError> {
        for entry in std::fs::read_dir(path)? {
            let entry = entry?;
            let ty = entry.file_type()?;
            let p = entry.path();
            if ty.is_symlink() {
                let target = std::fs::canonicalize(&p).map_err(|e| {
                    PrebuiltError::Extract(format!("symlink '{}' cannot be resolved: {e}", p.display()))
                })?;
                if !target.starts_with(root) {
                    return Err(PrebuiltError::Extract(format!(
                        "symlink '{}' escapes extraction directory",
                        p.display()
                    )));
                }
            } else if ty.is_dir() {
                let c = p.canonicalize()?;
                if !c.starts_with(root) {
                    return Err(PrebuiltError::Extract(format!(
                        "directory '{}' escapes extraction directory",
                        p.display()
                    )));
                }
                walk(&p, root)?;
            } else if ty.is_file() {
                let c = p.canonicalize()?;
                if !c.starts_with(root) {
                    return Err(PrebuiltError::Extract(format!(
                        "file '{}' escapes extraction directory",
                        p.display()
                    )));
                }
            } else {
                return Err(PrebuiltError::Extract(format!(
                    "unsupported archive entry type '{}'",
                    p.display()
                )));
            }
        }
        Ok(())
    }
    walk(&canonical_root, &canonical_root)
}

/// Resolve the manifest-declared setup script to an absolute path
/// inside `plugin_dir`, or return `Ok(None)` if no setup is declared.
///
/// Returns `Err(EscapesPluginDir)` if the declared path is absolute
/// or contains `..`, or if the canonicalized path lives outside
/// `plugin_dir`. Returns `Err(NotFound)` if the resolved path doesn't
/// exist on disk.
///
/// This is the security gate — the async runner trusts the path it
/// gets from this function.
pub fn resolve_setup_script(
    manifest: &PluginManifest,
    plugin_dir: &Path,
) -> Result<Option<PathBuf>, SetupError> {
    // 1. Extension setup wins. The extension binary is what the host
    //    spawns immediately on session start, so its build script gets
    //    priority over the sidecar's.
    if let Some(ext) = manifest.extension.as_ref() {
        if let Some(setup) = ext.setup.as_deref() {
            return validate_setup_path(setup, plugin_dir).map(Some);
        }
    }
    // 2. Fall back to the sidecar's setup (legacy slot).
    if let Some(provides) = manifest.provides.as_ref() {
        if let Some(sidecar) = provides.sidecar.as_ref() {
            if let Some(setup) = sidecar.setup.as_deref() {
                return validate_setup_path(setup, plugin_dir).map(Some);
            }
        }
    }
    Ok(None)
}

/// Security-validate a setup-script path declared in the manifest and
/// resolve it to an absolute path inside `plugin_dir`.
///
/// Shared by both the `extension.setup` and `provides.sidecar.setup`
/// resolution paths so the rules stay identical.
fn validate_setup_path(setup: &str, plugin_dir: &Path) -> Result<PathBuf, SetupError> {
    let setup_path = Path::new(setup);
    if setup_path.is_absolute()
        || setup_path
            .components()
            .any(|c| matches!(c, std::path::Component::ParentDir))
    {
        return Err(SetupError::EscapesPluginDir {
            path: setup.to_string(),
        });
    }
    let joined = plugin_dir.join(setup_path);
    let canonical = match joined.canonicalize() {
        Ok(p) => p,
        Err(_) => {
            return Err(SetupError::NotFound {
                path: setup.to_string(),
            });
        }
    };
    let canonical_dir = plugin_dir
        .canonicalize()
        .unwrap_or_else(|_| plugin_dir.to_path_buf());
    if !canonical.starts_with(&canonical_dir) {
        return Err(SetupError::EscapesPluginDir {
            path: setup.to_string(),
        });
    }
    Ok(canonical)
}

/// Build the per-install log path. Caller is expected to create the
/// parent directory before opening it. Format:
///
/// `{logs_root}/install/{plugin}-{rfc3339}.log`
///
/// where rfc3339 has colons replaced with `-` so the filename is safe
/// on Windows (and grep-friendly).
pub fn install_log_path(logs_root: &Path, plugin_name: &str, now_rfc3339: &str) -> PathBuf {
    let safe_ts = safe_name_fragment(&now_rfc3339.replace(':', "-"));
    let safe_plugin = safe_name_fragment(plugin_name);
    logs_root
        .join("install")
        .join(format!("{safe_plugin}-{safe_ts}.log"))
}

/// Run the resolved setup script against `plugin_dir`, streaming
/// combined stdout+stderr to `log_path`. Returns on success, exit
/// code, timeout, or I/O error.
///
/// The script is invoked as `bash <script>` (POSIX shells only — no
/// Windows .bat/.ps1 support in v1; plugins on Windows can ship a
/// shim or rely on the native binary already being committed).
///
/// `cwd` is set to `plugin_dir` so scripts can use relative paths
/// like `target/release/...`.
pub async fn run_setup_script(
    script: &Path,
    plugin_dir: &Path,
    log_path: &Path,
    timeout: Duration,
) -> Result<SetupOutcome, SetupError> {
    use std::process::Stdio;
    use tokio::io::AsyncWriteExt;
    use tokio::process::Command;

    if let Some(parent) = log_path.parent() {
        std::fs::create_dir_all(parent)?;
    }
    let mut log_file = tokio::fs::File::create(log_path).await?;
    let header = format!(
        "$ bash {} (cwd: {})\n",
        script.display(),
        plugin_dir.display()
    );
    log_file.write_all(header.as_bytes()).await?;

    if cfg!(windows) {
        return Err(SetupError::Io(std::io::Error::new(
            std::io::ErrorKind::Unsupported,
            "setup scripts require bash and are not supported on Windows in this release",
        )));
    }

    let mut cmd = Command::new("bash");
    cmd.arg(script)
        .current_dir(plugin_dir)
        .env_clear()
        .env("PATH", std::env::var_os("PATH").unwrap_or_default())
        .env("HOME", std::env::var_os("HOME").unwrap_or_default())
        .env("USER", std::env::var_os("USER").unwrap_or_default())
        .env("SHELL", std::env::var_os("SHELL").unwrap_or_default())
        .env("SYNAPS_PLUGIN_DIR", plugin_dir)
        .stdin(Stdio::null())
        .stdout(Stdio::piped())
        .stderr(Stdio::piped())
        .kill_on_drop(true);

    let mut child = cmd.spawn()?;
    let mut stdout = child.stdout.take().expect("piped stdout");
    let mut stderr = child.stderr.take().expect("piped stderr");

    let copy_out = async {
        tokio::io::copy(&mut stdout, &mut log_file).await?;
        log_file.flush().await?;
        Ok::<_, std::io::Error>(log_file)
    };
    let collect_err = async {
        let mut buf = Vec::new();
        tokio::io::AsyncReadExt::read_to_end(&mut stderr, &mut buf).await?;
        Ok::<_, std::io::Error>(buf)
    };

    let wait = async {
        let (out_res, err_res, status) = tokio::join!(copy_out, collect_err, child.wait());
        let mut log_file = out_res?;
        let err_buf = err_res?;
        if !err_buf.is_empty() {
            log_file.write_all(b"\n--- stderr ---\n").await?;
            log_file.write_all(&err_buf).await?;
            log_file.flush().await?;
        }
        Ok::<_, std::io::Error>(status?)
    };

    let status = match tokio::time::timeout(timeout, wait).await {
        Ok(res) => res?,
        Err(_) => {
            return Err(SetupError::Timeout {
                secs: timeout.as_secs(),
                log_path: log_path.to_path_buf(),
            });
        }
    };

    let exit_code = status.code().unwrap_or(-1);
    if status.success() {
        Ok(SetupOutcome {
            log_path: log_path.to_path_buf(),
            exit_code,
        })
    } else {
        Err(SetupError::NonZeroExit {
            exit_code,
            log_path: log_path.to_path_buf(),
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::extensions::manifest::{ExtensionManifest, ExtensionRuntime};
    use crate::skills::manifest::{PluginProvides, SidecarManifest};
    use std::fs;

    #[test]
    fn host_triple_matches_compiled_target_when_supported() {
        // Run-time check: triple must be one of the known stable strings
        // on supported hosts (we test on linux/macos/windows in CI).
        let known = [
            "linux-x86_64", "linux-arm64",
            "darwin-x86_64", "darwin-arm64",
            "windows-x86_64", "windows-arm64",
        ];
        let got = host_triple();
        if cfg!(any(target_os = "linux", target_os = "macos", target_os = "windows"))
            && cfg!(any(target_arch = "x86_64", target_arch = "aarch64"))
        {
            let s = got.expect("supported host should yield a triple");
            assert!(known.contains(&s), "unexpected triple: {}", s);
        }
    }

    #[cfg(all(target_os = "linux", target_arch = "x86_64"))]
    #[test]
    fn host_triple_is_linux_x86_64_on_this_box() {
        // Sanity-pin for the dev box this is being authored on; harmless
        // elsewhere because of the cfg gate.
        assert_eq!(host_triple(), Some("linux-x86_64"));
    }

    fn manifest_with_setup(setup: Option<&str>) -> PluginManifest {
        PluginManifest {
            name: "test-plugin".to_string(),
            version: None,
            description: None,
            keybinds: vec![],
            compatibility: None,
            commands: vec![],
            extension: None,
            help_entries: vec![],
            provides: Some(PluginProvides {
                sidecar: Some(SidecarManifest {
                    command: "bin/sidecar".to_string(),
                    setup: setup.map(|s| s.to_string()),
                    protocol_version: 1,
                    model: None,
                    lifecycle: None,
                }),
            }),
            settings: None,
        }
    }

    /// Build an extension-only manifest with the given setup-script slot.
    fn manifest_with_extension_setup(setup: Option<&str>) -> PluginManifest {
        PluginManifest {
            name: "test-plugin".to_string(),
            version: None,
            description: None,
            keybinds: vec![],
            compatibility: None,
            commands: vec![],
            extension: Some(ExtensionManifest {
                protocol_version: 1,
                runtime: ExtensionRuntime::Process,
                command: "bin/ext".to_string(),
                setup: setup.map(|s| s.to_string()),
                prebuilt: ::std::collections::HashMap::new(),
                args: vec![],
                permissions: vec![],
                hooks: vec![],
                config: vec![],
            }),
            help_entries: vec![],
            provides: None,
            settings: None,
        }
    }

    /// Build a manifest with BOTH extension and sidecar setup slots.
    /// Used to verify extension wins when both are present.
    fn manifest_with_both_setup(ext_setup: &str, side_setup: &str) -> PluginManifest {
        let mut m = manifest_with_extension_setup(Some(ext_setup));
        m.provides = Some(PluginProvides {
            sidecar: Some(SidecarManifest {
                command: "bin/sidecar".to_string(),
                setup: Some(side_setup.to_string()),
                protocol_version: 1,
                model: None,
                lifecycle: None,
            }),
        });
        m
    }

    #[test]
    fn resolve_returns_none_when_no_setup_declared() {
        let m = manifest_with_setup(None);
        let dir = tempfile::tempdir().unwrap();
        let res = resolve_setup_script(&m, dir.path()).unwrap();
        assert!(res.is_none());
    }

    #[test]
    fn resolve_returns_none_when_no_provides() {
        let mut m = manifest_with_setup(None);
        m.provides = None;
        let dir = tempfile::tempdir().unwrap();
        assert!(resolve_setup_script(&m, dir.path()).unwrap().is_none());
    }

    #[test]
    fn resolve_resolves_relative_path_inside_plugin_dir() {
        let dir = tempfile::tempdir().unwrap();
        let scripts = dir.path().join("scripts");
        fs::create_dir(&scripts).unwrap();
        fs::write(scripts.join("setup.sh"), "#!/bin/bash\necho ok").unwrap();
        let m = manifest_with_setup(Some("scripts/setup.sh"));
        let resolved = resolve_setup_script(&m, dir.path()).unwrap().unwrap();
        assert!(resolved.ends_with("scripts/setup.sh"));
        assert!(resolved.is_absolute());
    }

    #[test]
    fn resolve_rejects_absolute_path() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_setup(Some("/etc/passwd"));
        let err = resolve_setup_script(&m, dir.path()).unwrap_err();
        assert!(matches!(err, SetupError::EscapesPluginDir { .. }), "got {err:?}");
    }

    #[test]
    fn resolve_rejects_parent_dir_traversal() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_setup(Some("../escape.sh"));
        let err = resolve_setup_script(&m, dir.path()).unwrap_err();
        assert!(matches!(err, SetupError::EscapesPluginDir { .. }), "got {err:?}");
    }

    #[test]
    fn resolve_rejects_embedded_parent_dir() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_setup(Some("scripts/../../etc/passwd"));
        let err = resolve_setup_script(&m, dir.path()).unwrap_err();
        assert!(matches!(err, SetupError::EscapesPluginDir { .. }), "got {err:?}");
    }

    #[test]
    fn resolve_returns_not_found_when_script_missing() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_setup(Some("scripts/missing.sh"));
        let err = resolve_setup_script(&m, dir.path()).unwrap_err();
        assert!(matches!(err, SetupError::NotFound { .. }), "got {err:?}");
    }

    #[test]
    fn resolve_rejects_symlink_pointing_outside_plugin_dir() {
        // Symlinks that escape via canonicalize should be caught by the
        // starts_with(canonical_dir) check.
        let outer = tempfile::tempdir().unwrap();
        let dir = tempfile::tempdir().unwrap();
        let target = outer.path().join("escape.sh");
        fs::write(&target, "#!/bin/bash").unwrap();
        let scripts = dir.path().join("scripts");
        fs::create_dir(&scripts).unwrap();
        let link = scripts.join("setup.sh");
        std::os::unix::fs::symlink(&target, &link).unwrap();
        let m = manifest_with_setup(Some("scripts/setup.sh"));
        let err = resolve_setup_script(&m, dir.path()).unwrap_err();
        assert!(matches!(err, SetupError::EscapesPluginDir { .. }), "got {err:?}");
    }

    #[test]
    fn install_log_path_substitutes_colons() {
        let path = install_log_path(
            Path::new("/tmp/logs"),
            "sample-sidecar",
            "2026-05-02T19:30:45-04:00",
        );
        assert_eq!(
            path,
            PathBuf::from("/tmp/logs/install/sample-sidecar-2026-05-02T19-30-45-04-00.log")
        );
    }

    #[tokio::test]
    async fn run_setup_succeeds_for_simple_script() {
        let dir = tempfile::tempdir().unwrap();
        let scripts = dir.path().join("scripts");
        fs::create_dir(&scripts).unwrap();
        let script = scripts.join("setup.sh");
        fs::write(
            &script,
            "#!/bin/bash\necho hello-from-setup\necho 'on stderr' >&2\n",
        )
        .unwrap();
        use std::os::unix::fs::PermissionsExt;
        fs::set_permissions(&script, fs::Permissions::from_mode(0o755)).unwrap();
        let log = dir.path().join("install.log");
        let outcome = run_setup_script(&script, dir.path(), &log, Duration::from_secs(5))
            .await
            .unwrap();
        assert_eq!(outcome.exit_code, 0);
        assert_eq!(outcome.log_path, log);
        let captured = fs::read_to_string(&log).unwrap();
        assert!(captured.contains("hello-from-setup"));
        assert!(captured.contains("on stderr"));
    }

    #[tokio::test]
    async fn run_setup_returns_non_zero_exit() {
        let dir = tempfile::tempdir().unwrap();
        let script = dir.path().join("fail.sh");
        fs::write(&script, "#!/bin/bash\necho boom\nexit 7\n").unwrap();
        let log = dir.path().join("install.log");
        let err = run_setup_script(&script, dir.path(), &log, Duration::from_secs(5))
            .await
            .unwrap_err();
        match err {
            SetupError::NonZeroExit { exit_code, log_path } => {
                assert_eq!(exit_code, 7);
                assert_eq!(log_path, log);
                let captured = fs::read_to_string(&log).unwrap();
                assert!(captured.contains("boom"));
            }
            other => panic!("expected NonZeroExit, got {other:?}"),
        }
    }

    #[tokio::test]
    async fn run_setup_times_out() {
        let dir = tempfile::tempdir().unwrap();
        let script = dir.path().join("loop.sh");
        fs::write(&script, "#!/bin/bash\nsleep 5\n").unwrap();
        let log = dir.path().join("install.log");
        let err = run_setup_script(&script, dir.path(), &log, Duration::from_millis(200))
            .await
            .unwrap_err();
        assert!(matches!(err, SetupError::Timeout { .. }), "got {err:?}");
    }

    // ── extension.setup coverage (added by feat/extension-setup-script) ──

    #[test]
    fn resolve_resolves_extension_setup_path() {
        let dir = tempfile::tempdir().unwrap();
        let scripts = dir.path().join("scripts");
        fs::create_dir(&scripts).unwrap();
        fs::write(scripts.join("setup.sh"), "#!/bin/bash\necho ok").unwrap();
        let m = manifest_with_extension_setup(Some("scripts/setup.sh"));
        let resolved = resolve_setup_script(&m, dir.path()).unwrap().unwrap();
        assert!(resolved.ends_with("scripts/setup.sh"));
        assert!(resolved.is_absolute());
    }

    #[test]
    fn resolve_returns_none_when_extension_has_no_setup() {
        let m = manifest_with_extension_setup(None);
        let dir = tempfile::tempdir().unwrap();
        assert!(resolve_setup_script(&m, dir.path()).unwrap().is_none());
    }

    #[test]
    fn resolve_rejects_extension_setup_with_parent_dir() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_extension_setup(Some("../escape.sh"));
        let err = resolve_setup_script(&m, dir.path()).unwrap_err();
        assert!(
            matches!(err, SetupError::EscapesPluginDir { .. }),
            "got {err:?}"
        );
    }

    #[test]
    fn resolve_rejects_extension_setup_when_absolute() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_extension_setup(Some("/etc/passwd"));
        let err = resolve_setup_script(&m, dir.path()).unwrap_err();
        assert!(
            matches!(err, SetupError::EscapesPluginDir { .. }),
            "got {err:?}"
        );
    }

    #[test]
    fn resolve_returns_not_found_for_missing_extension_setup() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_extension_setup(Some("scripts/missing.sh"));
        let err = resolve_setup_script(&m, dir.path()).unwrap_err();
        assert!(matches!(err, SetupError::NotFound { .. }), "got {err:?}");
    }

    #[test]
    fn resolve_prefers_extension_setup_over_sidecar_setup() {
        // When both slots are populated, extension wins — the host spawns
        // the extension binary first on session start, so its build must
        // run first.
        let dir = tempfile::tempdir().unwrap();
        let scripts = dir.path().join("scripts");
        fs::create_dir(&scripts).unwrap();
        fs::write(scripts.join("ext.sh"), "#!/bin/bash\necho ext").unwrap();
        fs::write(scripts.join("side.sh"), "#!/bin/bash\necho side").unwrap();
        let m = manifest_with_both_setup("scripts/ext.sh", "scripts/side.sh");
        let resolved = resolve_setup_script(&m, dir.path()).unwrap().unwrap();
        assert!(
            resolved.ends_with("scripts/ext.sh"),
            "expected extension setup to win, got {resolved:?}"
        );
    }

    #[test]
    fn resolve_falls_back_to_sidecar_when_extension_has_no_setup() {
        // Plugin has an extension but no extension.setup, plus a sidecar
        // with setup. The sidecar's setup should still run (legacy slot
        // remains honoured).
        let dir = tempfile::tempdir().unwrap();
        let scripts = dir.path().join("scripts");
        fs::create_dir(&scripts).unwrap();
        fs::write(scripts.join("side.sh"), "#!/bin/bash\necho side").unwrap();
        let mut m = manifest_with_extension_setup(None); // extension present, no setup
        m.provides = Some(PluginProvides {
            sidecar: Some(SidecarManifest {
                command: "bin/sidecar".to_string(),
                setup: Some("scripts/side.sh".to_string()),
                protocol_version: 1,
                model: None,
                lifecycle: None,
            }),
        });
        let resolved = resolve_setup_script(&m, dir.path()).unwrap().unwrap();
        assert!(resolved.ends_with("scripts/side.sh"));
    }

    #[test]
    fn resolve_returns_none_when_neither_slot_has_setup() {
        // Plugin has both extension and sidecar declared, but neither
        // declares a setup script — function returns Ok(None).
        let dir = tempfile::tempdir().unwrap();
        let mut m = manifest_with_extension_setup(None);
        m.provides = Some(PluginProvides {
            sidecar: Some(SidecarManifest {
                command: "bin/sidecar".to_string(),
                setup: None,
                protocol_version: 1,
                model: None,
                lifecycle: None,
            }),
        });
        assert!(resolve_setup_script(&m, dir.path()).unwrap().is_none());
    }

    // ---- verify_extension_command tests (slice C) ----

    /// Helper: build a manifest whose extension declares `command`.
    fn manifest_with_extension_command(command: &str) -> PluginManifest {
        PluginManifest {
            name: "test-plugin".to_string(),
            version: None,
            description: None,
            keybinds: vec![],
            compatibility: None,
            commands: vec![],
            extension: Some(ExtensionManifest {
                protocol_version: 1,
                runtime: ExtensionRuntime::Process,
                command: command.to_string(),
                setup: None,
                prebuilt: ::std::collections::HashMap::new(),
                args: vec![],
                permissions: vec![],
                hooks: vec![],
                config: vec![],
            }),
            help_entries: vec![],
            provides: None,
            settings: None,
        }
    }

    #[test]
    fn verify_returns_ok_none_when_no_extension() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_setup(None); // sidecar-only manifest
        assert_eq!(verify_extension_command(&m, dir.path()).unwrap(), None);
    }

    #[test]
    fn verify_returns_ok_none_for_bare_command_name() {
        // Bare names defer to PATH lookup at spawn time, not our concern.
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_extension_command("python3");
        assert_eq!(verify_extension_command(&m, dir.path()).unwrap(), None);
    }

    #[test]
    fn verify_succeeds_when_relative_binary_exists_and_is_executable() {
        let dir = tempfile::tempdir().unwrap();
        let bin = dir.path().join("bin/ext");
        fs::create_dir_all(bin.parent().unwrap()).unwrap();
        fs::write(&bin, "#!/bin/sh\necho ok").unwrap();
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            fs::set_permissions(&bin, fs::Permissions::from_mode(0o755)).unwrap();
        }
        let m = manifest_with_extension_command("bin/ext");
        let resolved = verify_extension_command(&m, dir.path()).unwrap();
        assert!(resolved.is_some(), "should return resolved path");
    }

    #[test]
    fn verify_returns_missing_when_binary_absent() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_extension_command("bin/ext");
        let err = verify_extension_command(&m, dir.path()).unwrap_err();
        assert!(matches!(err, CommandVerifyError::Missing { .. }), "got: {err:?}");
    }

    #[cfg(unix)]
    #[test]
    fn verify_returns_not_executable_when_bit_missing() {
        let dir = tempfile::tempdir().unwrap();
        let bin = dir.path().join("bin/ext");
        fs::create_dir_all(bin.parent().unwrap()).unwrap();
        fs::write(&bin, "data").unwrap();
        use std::os::unix::fs::PermissionsExt;
        fs::set_permissions(&bin, fs::Permissions::from_mode(0o644)).unwrap();
        let m = manifest_with_extension_command("bin/ext");
        let err = verify_extension_command(&m, dir.path()).unwrap_err();
        assert!(matches!(err, CommandVerifyError::NotExecutable { .. }), "got: {err:?}");
    }

    #[test]
    fn verify_returns_not_a_file_when_path_is_directory() {
        let dir = tempfile::tempdir().unwrap();
        let bin = dir.path().join("bin/ext");
        fs::create_dir_all(&bin).unwrap();
        let m = manifest_with_extension_command("bin/ext");
        let err = verify_extension_command(&m, dir.path()).unwrap_err();
        assert!(matches!(err, CommandVerifyError::NotAFile { .. }), "got: {err:?}");
    }

    #[test]
    fn verify_rejects_parent_dir_traversal_in_command() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_extension_command("../escape/bin");
        let err = verify_extension_command(&m, dir.path()).unwrap_err();
        assert!(matches!(err, CommandVerifyError::EscapesPluginDir { .. }), "got: {err:?}");
    }

    #[cfg(unix)]
    #[test]
    fn verify_rejects_symlink_pointing_outside_plugin_dir() {
        let outer = tempfile::tempdir().unwrap();
        let plugin = tempfile::tempdir().unwrap();
        // Create a target binary outside the plugin dir.
        let target = outer.path().join("real-bin");
        fs::write(&target, "x").unwrap();
        use std::os::unix::fs::PermissionsExt;
        fs::set_permissions(&target, fs::Permissions::from_mode(0o755)).unwrap();
        // Symlink inside the plugin dir to that outside binary.
        let link = plugin.path().join("bin/ext");
        fs::create_dir_all(link.parent().unwrap()).unwrap();
        std::os::unix::fs::symlink(&target, &link).unwrap();
        let m = manifest_with_extension_command("bin/ext");
        let err = verify_extension_command(&m, plugin.path()).unwrap_err();
        assert!(
            matches!(err, CommandVerifyError::EscapesPluginDir { .. }),
            "got: {err:?}"
        );
    }


    #[test]
    fn verify_rejects_absolute_extension_command() {
        let dir = tempfile::tempdir().unwrap();
        let m = manifest_with_extension_command("/tmp/ext");
        let err = verify_extension_command(&m, dir.path()).unwrap_err();
        assert!(matches!(err, CommandVerifyError::EscapesPluginDir { .. }), "got: {err:?}");
    }

    #[test]
    fn policy_normalizes_sha256_and_sanitizes_names() {
        assert_eq!(normalize_sha256(&"A".repeat(64)).unwrap(), "a".repeat(64));
        assert!(normalize_sha256("not-a-sha").is_none());
        assert_eq!(safe_name_fragment("../bad\nname"), "bad_name");
        assert_eq!(safe_name_fragment("normal-name_1.2"), "normal-name_1.2");
    }

    // ---- try_install_from_prebuilt tests (slice E) ----

    fn manifest_with_prebuilt(
        command: &str,
        triple: &str,
        url: &str,
        sha256: &str,
    ) -> PluginManifest {
        let mut prebuilt = std::collections::HashMap::new();
        prebuilt.insert(
            triple.to_string(),
            crate::extensions::manifest::PrebuiltAsset {
                url: url.to_string(),
                sha256: sha256.to_string(),
            },
        );
        PluginManifest {
            name: "test-plugin".to_string(),
            version: None,
            description: None,
            keybinds: vec![],
            compatibility: None,
            commands: vec![],
            extension: Some(ExtensionManifest {
                protocol_version: 1,
                runtime: ExtensionRuntime::Process,
                command: command.to_string(),
                setup: None,
                prebuilt,
                args: vec![],
                permissions: vec![],
                hooks: vec![],
                config: vec![],
            }),
            help_entries: vec![],
            provides: None,
            settings: None,
        }
    }

    /// Helper: create a tar.gz archive containing one executable file at
    /// the given relative path inside the archive. Returns the archive
    /// path and its SHA-256.
    fn mk_tarball(staging: &Path, archive_name: &str, inner_path: &str) -> (PathBuf, String) {
        let work = staging.join("staging");
        fs::create_dir_all(&work).unwrap();
        let payload = work.join(inner_path);
        fs::create_dir_all(payload.parent().unwrap()).unwrap();
        fs::write(&payload, "#!/bin/sh\necho prebuilt-bin\n").unwrap();
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            fs::set_permissions(&payload, fs::Permissions::from_mode(0o755)).unwrap();
        }
        let archive = staging.join(archive_name);
        let out = std::process::Command::new("tar")
            .arg("-czf")
            .arg(&archive)
            .arg("-C")
            .arg(&work)
            .arg(inner_path)
            .output()
            .expect("system tar must be present");
        assert!(out.status.success(), "tar failed: {:?}", out);
        let bytes = fs::read(&archive).unwrap();
        use sha2::{Digest, Sha256};
        let mut h = Sha256::new();
        h.update(&bytes);
        let sha = hex_encode_lower(&h.finalize());
        (archive, sha)
    }

    #[tokio::test(flavor = "current_thread")]
    async fn prebuilt_returns_no_matching_asset_when_triple_missing() {
        let dir = tempfile::tempdir().unwrap();
        // Asset under a deliberately wrong host triple.
        let m = manifest_with_prebuilt("bin/ext", "fake-triple-9999", "https://x", "00");
        let err = try_install_from_prebuilt(&m, dir.path()).await.unwrap_err();
        assert!(matches!(err, PrebuiltError::NoMatchingAsset), "got: {err:?}");
    }

    #[tokio::test(flavor = "current_thread")]
    async fn prebuilt_rejects_non_https_url_in_production_builds() {
        // file:// is test-only; http:// is always blocked.
        let dir = tempfile::tempdir().unwrap();
        let triple = host_triple().expect("supported host");
        let m = manifest_with_prebuilt("bin/ext", triple, "http://example.com/x.tar.gz", "00");
        let err = try_install_from_prebuilt(&m, dir.path()).await.unwrap_err();
        assert!(matches!(err, PrebuiltError::UnsafeUrl { .. }), "got: {err:?}");
    }

    #[tokio::test(flavor = "current_thread")]
    async fn prebuilt_succeeds_with_valid_tarball_and_checksum() {
                let staging = tempfile::tempdir().unwrap();
        let plugin = tempfile::tempdir().unwrap();
        let (archive, sha) = mk_tarball(staging.path(), "ext.tar.gz", "bin/ext");
        let url = format!("file://{}", archive.display());
        let triple = host_triple().expect("supported host");
        let m = manifest_with_prebuilt("bin/ext", triple, &url, &sha);
        let resolved = try_install_from_prebuilt(&m, plugin.path()).await.unwrap();
        assert!(resolved.exists(), "extracted binary should exist at {}", resolved.display());
        // Also confirm the temp download file was cleaned up.
        let leftover = plugin.path().join(format!(".prebuilt-{}-download", triple));
        assert!(!leftover.exists(), "temp archive should be removed");
    }

    #[tokio::test(flavor = "current_thread")]
    async fn prebuilt_aborts_on_checksum_mismatch_without_extracting() {
                let staging = tempfile::tempdir().unwrap();
        let plugin = tempfile::tempdir().unwrap();
        let (archive, _real_sha) = mk_tarball(staging.path(), "ext.tar.gz", "bin/ext");
        let url = format!("file://{}", archive.display());
        let triple = host_triple().expect("supported host");
        let bad_sha = "0".repeat(64);
        let m = manifest_with_prebuilt("bin/ext", triple, &url, &bad_sha);
        let err = try_install_from_prebuilt(&m, plugin.path()).await.unwrap_err();
        match err {
            PrebuiltError::ChecksumMismatch { expected, actual } => {
                assert_eq!(expected, bad_sha);
                assert_eq!(actual.len(), 64, "actual sha should be lowercase hex");
            }
            other => panic!("expected ChecksumMismatch, got {other:?}"),
        }
        // No artifact should have been written.
        assert!(!plugin.path().join("bin/ext").exists());
    }

    #[tokio::test(flavor = "current_thread")]
    async fn prebuilt_rejects_unsupported_archive_suffix() {
                let staging = tempfile::tempdir().unwrap();
        let plugin = tempfile::tempdir().unwrap();
        // Make a .rar-named file (we only support tar/zip variants).
        let archive = staging.path().join("ext.rar");
        fs::write(&archive, b"not really a rar").unwrap();
        let bytes = fs::read(&archive).unwrap();
        use sha2::{Digest, Sha256};
        let mut h = Sha256::new();
        h.update(&bytes);
        let sha = hex_encode_lower(&h.finalize());
        let url = format!("file://{}", archive.display());
        let triple = host_triple().expect("supported host");
        let m = manifest_with_prebuilt("bin/ext", triple, &url, &sha);
        let err = try_install_from_prebuilt(&m, plugin.path()).await.unwrap_err();
        assert!(matches!(err, PrebuiltError::UnsupportedArchive { .. }), "got: {err:?}");
    }

    #[tokio::test(flavor = "current_thread")]
    async fn prebuilt_fails_verify_when_archive_does_not_contain_declared_command() {
                let staging = tempfile::tempdir().unwrap();
        let plugin = tempfile::tempdir().unwrap();
        // Archive ships at bin/wrong-name but manifest declares bin/ext.
        let (archive, sha) = mk_tarball(staging.path(), "ext.tar.gz", "bin/wrong-name");
        let url = format!("file://{}", archive.display());
        let triple = host_triple().expect("supported host");
        let m = manifest_with_prebuilt("bin/ext", triple, &url, &sha);
        let err = try_install_from_prebuilt(&m, plugin.path()).await.unwrap_err();
        assert!(matches!(err, PrebuiltError::Verify(_)), "got: {err:?}");
    }
}