cli/

install.rs

//! `mushroomdb install` / `uninstall` — wire the /mushroom skill and MCP
//! server into Claude Code and Cursor.
//!
//! # Design notes
//!
//! - No network: writes local config only; binary is already on disk.
//! - Idempotent: running install twice is a no-op (exit 0).
//! - Non-destructive: refuses to overwrite user files install didn't create.
//! - Manifest-driven uninstall: tracks every file written; removes exactly
//!   what install created.
//!
//! # User-scope MCP config location (verified 2026-09-02 by live inspection)
//!
//! Claude Code user-level MCP servers live in `~/.claude.json` under the
//! top-level `"mcpServers"` key. This was verified empirically on a live
//! Claude Code install: `~/.claude/settings.json` holds env/permissions/hooks
//! but NO mcpServers key. Cursor uses `~/.cursor/mcp.json` (same format as
//! project-level `.cursor/mcp.json`).

use crate::CliError;
use serde::{Deserialize, Serialize};
use std::fs;
use std::path::{Path, PathBuf};

// Template files embedded at compile time. Files live inside the crates/cli
// package so `cargo package` includes them in the published tarball.
// Path is relative to this source file (crates/cli/src/install.rs).
const SKILL_TEMPLATE: &str = include_str!("../skills/mushroom/SKILL.md");
const CURSOR_RULES_TEMPLATE: &str = include_str!("../skills/mushroom/cursor-rules.mdc");

/// Placeholder string replaced with the real db path in embedded templates.
const DB_PATH_PLACEHOLDER: &str = "{{DB_PATH}}";

/// Placeholder string replaced with the command that invokes mushroomdb —
/// the bare name when it is on PATH, else the absolute path of the stable copy.
const BIN_PLACEHOLDER: &str = "{{BIN}}";

/// The MCP server name we write. Must not be changed without a migration.
const SERVER_NAME: &str = "mushroomdb";

/// The binary name looked up on PATH and used as the bare MCP command.
const BIN_NAME: &str = "mushroomdb";

/// How the MCP server entry (and the skill's bootstrap commands) invoke
/// mushroomdb.
///
/// The assistant host spawns the MCP server by `command`; a bare name only
/// works if it resolves on the host's PATH. `npx mushroomdb install` and a
/// local `target/release` build both run install from a binary that is NOT
/// on PATH, so writing the bare name silently produces a server that never
/// connects. In that case we copy the running executable to a stable,
/// install-owned location and write its absolute path instead.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum BinaryLocation {
    /// `mushroomdb` resolves on PATH: write the bare name (upgrade-safe).
    OnPath,
    /// Not on PATH: copy this executable to `<home>/.mushroomdb/bin/mushroomdb`
    /// and write that absolute path.
    CopyFrom(PathBuf),
}

/// Decide how the MCP entry should invoke mushroomdb, from the real
/// environment: PATH lookup first, else the current executable.
pub fn detect_binary_location() -> BinaryLocation {
    if bin_on_path() {
        return BinaryLocation::OnPath;
    }
    match std::env::current_exe() {
        Ok(exe) => BinaryLocation::CopyFrom(exe),
        // Cannot locate ourselves — fall back to the bare name rather than fail.
        Err(_) => BinaryLocation::OnPath,
    }
}

fn bin_on_path() -> bool {
    let Some(path) = std::env::var_os("PATH") else {
        return false;
    };
    std::env::split_paths(&path).any(|dir| dir.join(BIN_NAME).is_file())
}

/// Stable, install-owned location for the copied binary (user-level, so a
/// project-scope install still yields a command that works from any cwd).
fn stable_bin_path(home: &Path) -> PathBuf {
    home.join(".mushroomdb").join("bin").join(BIN_NAME)
}

/// Which assistant platform(s) to wire up.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum Platform {
    ClaudeCode,
    Cursor,
    All,
}

impl Platform {
    pub fn parse(s: &str) -> Result<Self, String> {
        match s {
            "claude-code" => Ok(Platform::ClaudeCode),
            "cursor" => Ok(Platform::Cursor),
            "all" => Ok(Platform::All),
            other => Err(format!(
                "--platform must be claude-code | cursor | all, got: {other}"
            )),
        }
    }
}

/// Options parsed from `mushroomdb install [flags]` or `mushroomdb uninstall [flags]`.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct InstallOpts {
    /// Which platform to wire up. `None` = auto-detect.
    pub platform: Option<Platform>,
    /// Project scope (`--project`). If false → user scope.
    pub project: bool,
    /// Database directory. `None` = use the scope default.
    pub db: Option<PathBuf>,
}

impl InstallOpts {
    pub fn default_db(&self, project_root: &Path, home: &Path) -> PathBuf {
        if self.project {
            project_root.join("mushroom-memory")
        } else {
            home.join(".mushroomdb").join("memory")
        }
    }
}

// ---------------------------------------------------------------------------
// Manifest — tracks everything install wrote so uninstall can undo it.
// ---------------------------------------------------------------------------

#[derive(Serialize, Deserialize, Default, Debug)]
struct Manifest {
    /// Files created by this install (absolute paths).
    files: Vec<PathBuf>,
    /// MCP JSON keys added by this install.
    mcp_keys: Vec<ManagedMcpKey>,
    /// Hook entries added to a settings.json by this install.
    #[serde(default)]
    hooks: Vec<ManagedHook>,
}

#[derive(Serialize, Deserialize, Debug, Clone)]
struct ManagedMcpKey {
    /// The JSON file the key was added to (absolute path).
    file: PathBuf,
    /// The key inside `mcpServers`.
    server: String,
}

#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq)]
struct ManagedHook {
    /// The settings.json file the hook was added to (absolute path).
    file: PathBuf,
    /// The hook event name (e.g. `UserPromptSubmit`).
    event: String,
    /// The exact command string that was added.
    command: String,
}

/// Claude Code hook event this install wires: fires before each prompt is
/// sent, so the recall digest lands as context ahead of the user's turn.
const HOOK_EVENT: &str = "UserPromptSubmit";
/// Kept short: the hook must never noticeably slow a prompt.
const HOOK_TIMEOUT_SECS: u64 = 5;

/// Single-quote `s` for embedding in a POSIX shell command line, escaping
/// embedded single quotes as `'\''`. Claude Code runs a `type: "command"`
/// hook through a shell, so an unquoted path containing whitespace or shell
/// metacharacters is word-split and the hook silently receives the wrong
/// arguments — quoting both interpolations keeps the command exact.
fn sh_quote(s: &str) -> String {
    format!("'{}'", s.replace('\'', r"'\''"))
}

/// The exact command string written into the hook entry.
fn recall_hook_command(bin_cmd: &str, db_str: &str) -> String {
    format!("{} recall {}", sh_quote(bin_cmd), sh_quote(db_str))
}

/// One `hooks.<event>` array entry in Claude Code's settings.json shape.
fn hook_entry(command: &str) -> serde_json::Value {
    serde_json::json!({ "hooks": [ { "type": "command", "command": command, "timeout": HOOK_TIMEOUT_SECS } ] })
}

/// True if any hook group under `event` contains a command hook equal to `command`.
fn settings_has_hook(root: &serde_json::Value, event: &str, command: &str) -> bool {
    root["hooks"][event]
        .as_array()
        .map(|groups| {
            groups.iter().any(|g| {
                g["hooks"]
                    .as_array()
                    .map(|hs| hs.iter().any(|h| h["command"] == command))
                    .unwrap_or(false)
            })
        })
        .unwrap_or(false)
}

/// Add the recall hook to `settings_file` (created if absent). Idempotent:
/// no-op if the command is already present under `HOOK_EVENT`. Every other
/// key in the file — including other hook events and groups — is preserved.
/// Errors out (no write) rather than overwriting if `hooks` or
/// `hooks.<HOOK_EVENT>` already exists with an unexpected JSON type, or if
/// the file's top level is not a JSON object.
fn merge_hook_entry(
    settings_file: &Path,
    command: &str,
    manifest: &mut Manifest,
) -> Result<(), CliError> {
    let mut root: serde_json::Value = if settings_file.exists() {
        let raw = fs::read_to_string(settings_file)
            .map_err(|e| CliError(format!("cannot read {}: {e}", settings_file.display())))?;
        serde_json::from_str(&raw)
            .map_err(|e| CliError(format!("invalid JSON in {}: {e}", settings_file.display())))?
    } else {
        serde_json::json!({})
    };

    if !root.is_object() {
        return Err(CliError(format!(
            "{} is not a JSON object at its top level — refusing to add a hook",
            settings_file.display()
        )));
    }

    if settings_has_hook(&root, HOOK_EVENT, command) {
        return Ok(());
    }

    // Validate the shapes we are about to write into before touching
    // anything: a wrong-shaped `hooks` or `hooks.<event>` value belongs to
    // the user (or another tool) and must never be silently overwritten.
    match root.get("hooks") {
        None => root["hooks"] = serde_json::json!({}),
        Some(v) if v.is_object() => {}
        Some(_) => {
            return Err(CliError(format!(
                "{}: \"hooks\" is not a JSON object — refusing to overwrite it",
                settings_file.display()
            )));
        }
    }
    match root["hooks"].get(HOOK_EVENT) {
        None => root["hooks"][HOOK_EVENT] = serde_json::json!([]),
        Some(v) if v.is_array() => {}
        Some(_) => {
            return Err(CliError(format!(
                "{}: \"hooks.{HOOK_EVENT}\" is not a JSON array — refusing to overwrite it",
                settings_file.display()
            )));
        }
    }
    root["hooks"][HOOK_EVENT]
        .as_array_mut()
        .unwrap()
        .push(hook_entry(command));

    let parent = settings_file.parent().unwrap_or(Path::new("."));
    fs::create_dir_all(parent)
        .map_err(|e| CliError(format!("cannot create {}: {e}", parent.display())))?;
    let json = serde_json::to_string_pretty(&root)
        .map_err(|e| CliError(format!("cannot serialize settings: {e}")))?;
    fs::write(settings_file, json)
        .map_err(|e| CliError(format!("cannot write {}: {e}", settings_file.display())))?;

    manifest.hooks.push(ManagedHook {
        file: settings_file.to_path_buf(),
        event: HOOK_EVENT.into(),
        command: command.into(),
    });
    Ok(())
}

/// Remove exactly the hook groups whose only command is `command`; drop the
/// command from mixed groups; leave everything else semantically unchanged
/// (every key is re-serialized — comments are not supported since
/// `serde_json` is strict JSON).
///
/// Reads `hooks.<event>` through immutable accessors first, so a settings
/// file where the user removed the `hooks` key (or `<event>`, or shaped
/// either as something other than an object/array) is left byte-for-byte
/// untouched rather than having a stray `null` written back in.
fn remove_hook_entry(settings_file: &Path, event: &str, command: &str) -> Result<(), CliError> {
    if !settings_file.exists() {
        return Ok(());
    }
    let raw = fs::read_to_string(settings_file)
        .map_err(|e| CliError(format!("cannot read {}: {e}", settings_file.display())))?;
    let mut root: serde_json::Value = serde_json::from_str(&raw).map_err(|e| {
        CliError(format!(
            "corrupt settings json at {}: {e}",
            settings_file.display()
        ))
    })?;

    let Some(mut groups) = root
        .get("hooks")
        .and_then(|h| h.get(event))
        .and_then(|g| g.as_array())
        .cloned()
    else {
        // No matching (or well-shaped) event array — nothing of ours to
        // remove; leave the file exactly as it is, no write at all.
        return Ok(());
    };

    for g in groups.iter_mut() {
        if let Some(hs) = g["hooks"].as_array_mut() {
            hs.retain(|h| h["command"] != command);
        }
    }
    groups.retain(|g| {
        g["hooks"]
            .as_array()
            .map(|hs| !hs.is_empty())
            .unwrap_or(true)
    });

    let before = root.clone();
    if groups.is_empty() {
        root["hooks"].as_object_mut().unwrap().remove(event);
    } else {
        root["hooks"][event] = serde_json::Value::Array(groups);
    }
    if root == before {
        // The event array held none of our commands, so there is nothing to
        // remove. Writing anyway would re-serialize a file we do not own —
        // `serde_json` is built without `preserve_order`, so the user's key
        // order and indentation would be rewritten for no reason.
        return Ok(());
    }

    let json = serde_json::to_string_pretty(&root)
        .map_err(|e| CliError(format!("cannot serialize settings: {e}")))?;
    fs::write(settings_file, json)
        .map_err(|e| CliError(format!("cannot write {}: {e}", settings_file.display())))?;
    Ok(())
}

// ---------------------------------------------------------------------------
// Public entry points
// ---------------------------------------------------------------------------

/// Install the /mushroom skill and MCP server entry for the resolved platforms.
///
/// `project_root` is the directory where project-scope config files live
/// (`.mcp.json`, `.claude/`, `.cursor/`). `home` is the user HOME directory.
/// Tests pass temp directories for both; main.rs passes real values.
pub fn run_install(
    project_root: &Path,
    home: &Path,
    opts: &InstallOpts,
) -> Result<String, CliError> {
    run_install_with(project_root, home, opts, &detect_binary_location())
}

/// Like [`run_install`], but with the binary location supplied by the caller
/// instead of detected from PATH / `current_exe`. Tests use this to stay
/// deterministic; `run_install` is the real-environment wrapper.
pub fn run_install_with(
    project_root: &Path,
    home: &Path,
    opts: &InstallOpts,
    bin: &BinaryLocation,
) -> Result<String, CliError> {
    let db = opts
        .db
        .clone()
        .unwrap_or_else(|| opts.default_db(project_root, home));
    let db_str = db.to_string_lossy();

    let resolved = resolve_platform(project_root, home, opts.platform.as_ref())?;
    let platforms = expand_platform(&resolved);

    // Check for any conflicts before writing anything (atomic from user's POV).
    for plat in &platforms {
        preflight_check(project_root, home, plat, opts.project, &db_str)?;
    }

    let manifest_path = manifest_path(project_root, home, opts.project, &platforms);

    // Load the existing manifest so we can union it with what this run writes.
    // This covers partial-drift re-installs: if SKILL.md was edited but the MCP
    // entry is still intact, only the file is re-written this run; unioning
    // preserves the MCP key in the saved manifest so uninstall cleans it up too.
    let existing = load_manifest(&manifest_path);

    let mut manifest = Manifest::default();

    // Resolve the command the MCP entry and skill templates will use. For the
    // off-PATH case this copies the binary first so the path it names exists.
    let bin_cmd = match bin {
        BinaryLocation::OnPath => BIN_NAME.to_string(),
        BinaryLocation::CopyFrom(src) => {
            let dest = stable_bin_path(home);
            copy_binary(src, &dest, &mut manifest)?;
            dest.to_string_lossy().into_owned()
        }
    };

    for plat in &platforms {
        let step = install_platform(
            project_root,
            home,
            plat,
            opts.project,
            &db_str,
            &bin_cmd,
            &mut manifest,
        );
        if let Err(e) = step {
            // Persist whatever was already written (binary copy, earlier
            // platform's files) so uninstall can still clean up after a
            // partial failure. Best effort: the original error wins.
            let anything_written = !manifest.files.is_empty()
                || !manifest.mcp_keys.is_empty()
                || !manifest.hooks.is_empty();
            if anything_written {
                let merged = union_manifests(load_manifest(&manifest_path), &manifest);
                let _ = write_manifest(&manifest_path, &merged);
            }
            return Err(e);
        }
    }

    let anything_written =
        !manifest.files.is_empty() || !manifest.mcp_keys.is_empty() || !manifest.hooks.is_empty();

    if anything_written {
        // Union this-run entries with the existing manifest (dedup by path/key).
        let merged = union_manifests(existing, &manifest);
        write_manifest(&manifest_path, &merged)?;
    }

    let mut out = format!("mushroomdb installed ({} platform(s))\n", platforms.len());
    for f in &manifest.files {
        out.push_str(&format!("  wrote  {}\n", f.display()));
    }
    for k in &manifest.mcp_keys {
        out.push_str(&format!(
            "  added  mcpServers.{} in {}\n",
            k.server,
            k.file.display()
        ));
    }
    for h in &manifest.hooks {
        out.push_str(&format!(
            "  added  {} hook in {}\n",
            h.event,
            h.file.display()
        ));
    }
    if anything_written {
        out.push_str(&format!("  manifest  {}\n", manifest_path.display()));
        out.push_str(&format!(
            "  mcp command  {bin_cmd}\n  restart your assistant to connect the MCP server\n"
        ));
    } else {
        out.push_str("  (already installed — no changes)\n");
    }
    Ok(out)
}

/// Copy the running binary to its stable location. No-op if the bytes at
/// `dest` already match `src` (idempotent re-install); overwrites when they
/// differ (upgrade). Records `dest` in the manifest so uninstall removes it.
fn copy_binary(src: &Path, dest: &Path, manifest: &mut Manifest) -> Result<(), CliError> {
    let bytes = fs::read(src)
        .map_err(|e| CliError(format!("cannot read binary {}: {e}", src.display())))?;
    if fs::read(dest).map(|cur| cur == bytes).unwrap_or(false) {
        return Ok(());
    }
    let parent = dest.parent().unwrap_or(Path::new("."));
    fs::create_dir_all(parent)
        .map_err(|e| CliError(format!("cannot create {}: {e}", parent.display())))?;
    // Write to a temp name and rename so a running MCP server holding the old
    // inode keeps working and the swap is atomic.
    let tmp = parent.join(format!(".{BIN_NAME}.tmp-{}", std::process::id()));
    fs::write(&tmp, &bytes)
        .map_err(|e| CliError(format!("cannot write {}: {e}", tmp.display())))?;
    let finish = || -> Result<(), CliError> {
        #[cfg(unix)]
        {
            use std::os::unix::fs::PermissionsExt;
            fs::set_permissions(&tmp, fs::Permissions::from_mode(0o755))
                .map_err(|e| CliError(format!("cannot chmod {}: {e}", tmp.display())))?;
        }
        fs::rename(&tmp, dest)
            .map_err(|e| CliError(format!("cannot move binary into {}: {e}", dest.display())))
    };
    if let Err(e) = finish() {
        let _ = fs::remove_file(&tmp); // never leave an untracked temp file behind
        return Err(e);
    }
    manifest.files.push(dest.to_path_buf());
    Ok(())
}

/// Uninstall: remove exactly what install wrote. Reads the manifest.
pub fn run_uninstall(
    project_root: &Path,
    home: &Path,
    opts: &InstallOpts,
) -> Result<String, CliError> {
    let resolved = resolve_platform(project_root, home, opts.platform.as_ref())?;
    let platforms = expand_platform(&resolved);

    let manifest_path = manifest_path(project_root, home, opts.project, &platforms);
    if !manifest_path.exists() {
        return Err(CliError(format!(
            "no install manifest found at {} — nothing to uninstall",
            manifest_path.display()
        )));
    }

    let raw = fs::read_to_string(&manifest_path)
        .map_err(|e| CliError(format!("cannot read manifest: {e}")))?;
    let manifest: Manifest =
        serde_json::from_str(&raw).map_err(|e| CliError(format!("corrupt manifest: {e}")))?;

    let mut removed = Vec::new();

    // Remove MCP keys first (before files, in case files include .mcp.json).
    for key in &manifest.mcp_keys {
        if key.file.exists() {
            remove_mcp_key(&key.file, &key.server)?;
            removed.push(format!(
                "removed  mcpServers.{} from {}",
                key.server,
                key.file.display()
            ));
        }
    }

    // Remove hooks (before files, same reasoning as MCP keys).
    for h in &manifest.hooks {
        if h.file.exists() {
            remove_hook_entry(&h.file, &h.event, &h.command)?;
            removed.push(format!(
                "removed  {} hook from {}",
                h.event,
                h.file.display()
            ));
        }
    }

    // Remove files.
    for f in &manifest.files {
        if f.exists() {
            fs::remove_file(f)
                .map_err(|e| CliError(format!("cannot remove {}: {e}", f.display())))?;
            removed.push(format!("removed  {}", f.display()));
        }
    }

    // Remove the manifest itself.
    if manifest_path.exists() {
        fs::remove_file(&manifest_path)
            .map_err(|e| CliError(format!("cannot remove manifest: {e}")))?;
    }

    let mut out = "mushroomdb uninstalled\n".to_string();
    for line in &removed {
        out.push_str(&format!("  {line}\n"));
    }
    Ok(out)
}

// ---------------------------------------------------------------------------
// Platform resolution
// ---------------------------------------------------------------------------

fn resolve_platform(
    project_root: &Path,
    home: &Path,
    requested: Option<&Platform>,
) -> Result<Platform, CliError> {
    if let Some(p) = requested {
        return Ok(p.clone());
    }

    // Auto-detect.
    let has_claude = home.join(".claude").exists() || project_root.join(".claude").exists();
    let has_cursor = project_root.join(".cursor").exists() || home.join(".cursor").exists();

    match (has_claude, has_cursor) {
        (true, true) => Ok(Platform::All),
        (true, false) => Ok(Platform::ClaudeCode),
        (false, true) => Ok(Platform::Cursor),
        (false, false) => Err(CliError(
            "cannot auto-detect platform: neither ~/.claude nor .cursor/ found.\n\
             Pass --platform claude-code, --platform cursor, or --platform all."
                .to_string(),
        )),
    }
}

fn expand_platform(p: &Platform) -> Vec<Platform> {
    match p {
        Platform::All => vec![Platform::ClaudeCode, Platform::Cursor],
        Platform::ClaudeCode => vec![Platform::ClaudeCode],
        Platform::Cursor => vec![Platform::Cursor],
    }
}

// ---------------------------------------------------------------------------
// Pre-flight conflict check (no writes)
// ---------------------------------------------------------------------------

fn preflight_check(
    project_root: &Path,
    home: &Path,
    platform: &Platform,
    project_scope: bool,
    db_str: &str,
) -> Result<(), CliError> {
    match platform {
        Platform::ClaudeCode => {
            let mcp_file = if project_scope {
                project_root.join(".mcp.json")
            } else {
                // User-scope: verified empirically on a live Claude Code install.
                // ~/.claude.json holds top-level mcpServers; ~/.claude/settings.json
                // holds env/permissions/hooks but no mcpServers key.
                home.join(".claude.json")
            };
            check_mcp_conflict(&mcp_file, db_str)?;
        }
        Platform::Cursor => {
            let mcp_file = if project_scope {
                project_root.join(".cursor").join("mcp.json")
            } else {
                home.join(".cursor").join("mcp.json")
            };
            check_mcp_conflict(&mcp_file, db_str)?;
        }
        Platform::All => unreachable!("expand_platform never produces All"),
    }
    Ok(())
}

/// Check if a MCP JSON file has a conflicting `mushroomdb` entry.
///
/// A conflict is: the file exists, has `mcpServers.mushroomdb`, and its
/// `args[1]` (the db path) differs from what we'd write. An entry for the
/// SAME db with a different `command` is ours to repair (e.g. a bare name
/// that never resolved, or a stale absolute path after an upgrade), so it is
/// not a conflict.
fn check_mcp_conflict(mcp_file: &Path, db_str: &str) -> Result<(), CliError> {
    if !mcp_file.exists() {
        return Ok(());
    }
    let raw = fs::read_to_string(mcp_file)
        .map_err(|e| CliError(format!("cannot read {}: {e}", mcp_file.display())))?;
    let v: serde_json::Value = serde_json::from_str(&raw)
        .map_err(|e| CliError(format!("invalid JSON in {}: {e}", mcp_file.display())))?;

    let existing = &v["mcpServers"][SERVER_NAME];
    if existing.is_null() {
        return Ok(()); // Key absent — no conflict.
    }

    let existing_db = existing["args"]
        .get(1)
        .and_then(|v| v.as_str())
        .unwrap_or("");

    if existing_db == db_str {
        return Ok(()); // Same db — idempotent or repairable, no conflict.
    }

    Err(CliError(format!(
        "conflict: {} already has mcpServers.mushroomdb pointing to {:?}\n\
         To update it, run `mushroomdb uninstall` first, then re-install.\n\
         Or manually edit {} and remove the existing mushroomdb entry.",
        mcp_file.display(),
        existing_db,
        mcp_file.display()
    )))
}

// ---------------------------------------------------------------------------
// Per-platform installation
// ---------------------------------------------------------------------------

fn install_platform(
    project_root: &Path,
    home: &Path,
    platform: &Platform,
    project_scope: bool,
    db_str: &str,
    bin_cmd: &str,
    manifest: &mut Manifest,
) -> Result<(), CliError> {
    match platform {
        Platform::ClaudeCode => {
            install_claude_code(project_root, home, project_scope, db_str, bin_cmd, manifest)
        }
        Platform::Cursor => {
            install_cursor(project_root, home, project_scope, db_str, bin_cmd, manifest)
        }
        Platform::All => unreachable!("expand_platform never produces All"),
    }
}

/// Substitute both template placeholders.
fn render_template(template: &str, db_str: &str, bin_cmd: &str) -> String {
    template
        .replace(DB_PATH_PLACEHOLDER, db_str)
        .replace(BIN_PLACEHOLDER, bin_cmd)
}

fn install_claude_code(
    project_root: &Path,
    home: &Path,
    project_scope: bool,
    db_str: &str,
    bin_cmd: &str,
    manifest: &mut Manifest,
) -> Result<(), CliError> {
    let skill_content = render_template(SKILL_TEMPLATE, db_str, bin_cmd);

    let skill_dir = if project_scope {
        project_root.join(".claude").join("skills").join("mushroom")
    } else {
        home.join(".claude").join("skills").join("mushroom")
    };
    let skill_file = skill_dir.join("SKILL.md");

    // Idempotent: skip if the file already has the same content.
    if !file_matches(&skill_file, &skill_content) {
        fs::create_dir_all(&skill_dir)
            .map_err(|e| CliError(format!("cannot create {}: {e}", skill_dir.display())))?;
        fs::write(&skill_file, &skill_content)
            .map_err(|e| CliError(format!("cannot write {}: {e}", skill_file.display())))?;
        manifest.files.push(skill_file);
    }

    // MCP JSON. User-scope writes to ~/.claude.json (top-level mcpServers),
    // not ~/.claude/settings.json (which holds env/hooks, not mcpServers).
    let mcp_file = if project_scope {
        project_root.join(".mcp.json")
    } else {
        home.join(".claude.json")
    };
    merge_mcp_entry(&mcp_file, db_str, bin_cmd, manifest)?;

    // Recall hook: settings.json in the same scope as the skill.
    let settings_file = if project_scope {
        project_root.join(".claude").join("settings.json")
    } else {
        home.join(".claude").join("settings.json")
    };
    merge_hook_entry(
        &settings_file,
        &recall_hook_command(bin_cmd, db_str),
        manifest,
    )?;

    Ok(())
}

fn install_cursor(
    project_root: &Path,
    home: &Path,
    project_scope: bool,
    db_str: &str,
    bin_cmd: &str,
    manifest: &mut Manifest,
) -> Result<(), CliError> {
    let rules_content = render_template(CURSOR_RULES_TEMPLATE, db_str, bin_cmd);

    let rules_dir = if project_scope {
        project_root.join(".cursor").join("rules")
    } else {
        home.join(".cursor").join("rules")
    };
    let rules_file = rules_dir.join("mushroom.mdc");

    if !file_matches(&rules_file, &rules_content) {
        fs::create_dir_all(&rules_dir)
            .map_err(|e| CliError(format!("cannot create {}: {e}", rules_dir.display())))?;
        fs::write(&rules_file, &rules_content)
            .map_err(|e| CliError(format!("cannot write {}: {e}", rules_file.display())))?;
        manifest.files.push(rules_file);
    }

    // Cursor MCP JSON.
    let mcp_file = if project_scope {
        project_root.join(".cursor").join("mcp.json")
    } else {
        home.join(".cursor").join("mcp.json")
    };
    merge_mcp_entry(&mcp_file, db_str, bin_cmd, manifest)?;

    Ok(())
}

// ---------------------------------------------------------------------------
// MCP JSON merge helpers
// ---------------------------------------------------------------------------

/// Add `mcpServers.mushroomdb` to a JSON config file. Creates the file if
/// absent. No-op if the entry already matches (idempotent).
fn merge_mcp_entry(
    mcp_file: &Path,
    db_str: &str,
    bin_cmd: &str,
    manifest: &mut Manifest,
) -> Result<(), CliError> {
    let mut root: serde_json::Value = if mcp_file.exists() {
        let raw = fs::read_to_string(mcp_file)
            .map_err(|e| CliError(format!("cannot read {}: {e}", mcp_file.display())))?;
        serde_json::from_str(&raw)
            .map_err(|e| CliError(format!("invalid JSON in {}: {e}", mcp_file.display())))?
    } else {
        serde_json::json!({})
    };

    // Ensure `mcpServers` object exists.
    if !root["mcpServers"].is_object() {
        root["mcpServers"] = serde_json::json!({});
    }

    let desired = mcp_server_entry(db_str, bin_cmd);
    let existing = &root["mcpServers"][SERVER_NAME];

    if existing == &desired {
        return Ok(()); // Exact match — idempotent.
    }

    // Write the entry.
    root["mcpServers"][SERVER_NAME] = desired;

    let parent = mcp_file.parent().unwrap_or(Path::new("."));
    fs::create_dir_all(parent)
        .map_err(|e| CliError(format!("cannot create {}: {e}", parent.display())))?;

    let json = serde_json::to_string_pretty(&root)
        .map_err(|e| CliError(format!("cannot serialize mcp json: {e}")))?;
    fs::write(mcp_file, json)
        .map_err(|e| CliError(format!("cannot write {}: {e}", mcp_file.display())))?;

    manifest.mcp_keys.push(ManagedMcpKey {
        file: mcp_file.to_path_buf(),
        server: SERVER_NAME.to_string(),
    });

    Ok(())
}

/// Remove `mcpServers.<server>` from a JSON config file. Leaves the file in
/// place (with the key removed) unless `mcpServers` becomes empty, in which
/// case we still leave the file (the user may have other keys).
fn remove_mcp_key(mcp_file: &Path, server: &str) -> Result<(), CliError> {
    if !mcp_file.exists() {
        return Ok(());
    }
    let raw = fs::read_to_string(mcp_file)
        .map_err(|e| CliError(format!("cannot read {}: {e}", mcp_file.display())))?;
    let mut root: serde_json::Value = serde_json::from_str(&raw)
        .map_err(|e| CliError(format!("corrupt mcp json at {}: {e}", mcp_file.display())))?;

    if let Some(servers) = root["mcpServers"].as_object_mut() {
        servers.remove(server);
    }

    let json = serde_json::to_string_pretty(&root)
        .map_err(|e| CliError(format!("cannot serialize mcp json: {e}")))?;
    fs::write(mcp_file, json)
        .map_err(|e| CliError(format!("cannot write {}: {e}", mcp_file.display())))?;
    Ok(())
}

fn mcp_server_entry(db_str: &str, bin_cmd: &str) -> serde_json::Value {
    serde_json::json!({
        "command": bin_cmd,
        "args": ["mcp", db_str]
    })
}

// ---------------------------------------------------------------------------
// Manifest helpers
// ---------------------------------------------------------------------------

fn manifest_path(
    project_root: &Path,
    home: &Path,
    project_scope: bool,
    platforms: &[Platform],
) -> PathBuf {
    if !project_scope {
        return home.join(".mushroomdb").join("install-manifest.json");
    }
    // Project scope: prefer the Claude Code location; fall back to Cursor.
    if platforms.contains(&Platform::ClaudeCode) {
        project_root
            .join(".claude")
            .join("skills")
            .join("mushroom")
            .join(".install-manifest.json")
    } else {
        project_root.join(".cursor").join(".install-manifest.json")
    }
}

/// Load an existing manifest from `path`. Returns an empty manifest if absent or unparseable.
fn load_manifest(path: &Path) -> Manifest {
    let raw = match fs::read_to_string(path) {
        Ok(s) => s,
        Err(_) => return Manifest::default(),
    };
    serde_json::from_str(&raw).unwrap_or_default()
}

/// Union `existing` with `this_run`, deduplicating by path (files), by
/// (file, server) pair (mcp_keys), and by full equality (hooks). Entries from
/// `this_run` win on collision so the manifest always reflects the latest
/// state.
fn union_manifests(mut existing: Manifest, this_run: &Manifest) -> Manifest {
    for f in &this_run.files {
        if !existing.files.contains(f) {
            existing.files.push(f.clone());
        }
    }
    for k in &this_run.mcp_keys {
        let already = existing
            .mcp_keys
            .iter()
            .any(|e| e.file == k.file && e.server == k.server);
        if !already {
            existing.mcp_keys.push(k.clone());
        }
    }
    for h in &this_run.hooks {
        if !existing.hooks.contains(h) {
            existing.hooks.push(h.clone());
        }
    }
    existing
}

fn write_manifest(path: &Path, manifest: &Manifest) -> Result<(), CliError> {
    let parent = path.parent().unwrap_or(Path::new("."));
    fs::create_dir_all(parent).map_err(|e| {
        CliError(format!(
            "cannot create manifest dir {}: {e}",
            parent.display()
        ))
    })?;
    let json = serde_json::to_string_pretty(manifest)
        .map_err(|e| CliError(format!("cannot serialize manifest: {e}")))?;
    fs::write(path, json)
        .map_err(|e| CliError(format!("cannot write manifest {}: {e}", path.display())))?;
    Ok(())
}

// ---------------------------------------------------------------------------
// Utilities
// ---------------------------------------------------------------------------

/// True if the file exists and its content equals `expected`.
fn file_matches(path: &Path, expected: &str) -> bool {
    fs::read_to_string(path)
        .map(|s| s == expected)
        .unwrap_or(false)
}