[APP-4249] Set default cwd for project-scoped MCP servers (#9239)
## Description ### Motivation File-based stdio MCP servers spawned from a project's `.mcp.json` (e.g. `pnpm run mcp:foo`, or anything using `./tooling_scripts/...`) fail with: ``` Transport creation error: No such file or directory (os error 2) ``` Root cause: when the user's `.mcp.json` doesn't include a `working_directory`, Warp's spawner inherits whatever cwd Warp was launched from rather than the directory the config was discovered in. Two failure modes share this same root cause: - **Repo-relative commands/args** (e.g. `./tooling_scripts/foo`, `node ./src/server.js`) can't be resolved from outside the repo, so `execvp` returns `ENOENT`. - **Workspace-aware launchers** like `pnpm`/`npm`/`yarn` walk up from cwd looking for `package.json` (and workspace manifests). When cwd isn't inside the repo, they bail out before launching the requested script — surfacing as `ENOENT` from the spawner's perspective. `working_directory` is a Warp/VS-Code-style extension; the canonical Anthropic/Cursor MCP schemas don't include it, so most `.mcp.json` files in the wild don't set it. ### Implementation - New helper `FileBasedMCPManager::spawn_root_for_installation(uuid)` returning the discovery root for any file-based install: the repo root for project-scoped configs, the home directory for global configs (Warp and third-party). Returns `None` for non-file-based installs (e.g. cloud-templated ones), leaving them unaffected. Global Warp installs are remapped from `~/.warp/` (Warp internal state) to `~` so all global installs share a consistent cwd. - In `TemplatableMCPServerManager::spawn_server_impl`, default `cli_server.cwd_parameter` from this helper when unset. Single funnel — covers both auto-spawn and the manual UI opt-in path. User-supplied `working_directory` always wins. - ENOENT-aware logging at the spawn site: when `TokioChildProcess::spawn()` fails with `NotFound`, the MCP log file now spells out the server name, the missing executable, the cwd we used, and a hint pointing the user at `working_directory`. The user-surfaced error string is unchanged. - Documented the new defaulting behavior and `working_directory` override in `resources/bundled/skills/add-mcp-server/SKILL.md`. ## Testing Verified spawn-site behavior manually. Demo [here](https://www.loom.com/share/ec01d98ae9114433b8ae87f5f17adfd4)! - Added `test_parse_cli_server_preserves_explicit_working_directory` in `mod_test.rs` to lock in that an explicitly-set `working_directory` round-trips through parsing and won't be clobbered by the new defaulting logic. - Skipped a unit test for the new helper itself — it's a thin lookup over `file_based_servers_by_root` and the sorted-pick policy is straightforward enough to validate manually. - Spawn-site behavior (cwd actually applied, ENOENT log emission) verified manually against a `pnpm`\-based repro. ## Agent Mode - [x] Warp Agent Mode - This PR was created via Warp's AI Agent Mode ## Changelog Entries for Stable CHANGELOG-BUG-FIX: Project-scoped file-based MCP servers now spawn from the repo root by default (and global ones from `~`), so configs with relative commands/args (and workspace launchers like `pnpm`/`npm`) work without an explicit `working_directory`.
This commit is contained in:
Varoon Kodithala
@@ -404,6 +404,39 @@ impl FileBasedMCPManager {
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.sorted()
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.collect()
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}
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/// Returns the directory a file-based MCP installation should be spawned from
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/// when its config does not specify `working_directory`.
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///
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/// The spawn root is the directory the config was discovered in, with one
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/// exception: global Warp installs are discovered in `~/.warp/` (Warp's data
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/// dir) which isn't a useful cwd for spawned processes, so they are remapped
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/// to the home directory instead.
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/// - Project-scoped installations: the repo root.
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/// - Global installations (`~/.warp/.mcp.json`, `~/.claude.json`, etc.): the
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/// home directory.
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///
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/// If the installation is referenced from multiple roots, the lexicographically
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/// smallest is returned for determinism. Returns `None` for installations that
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/// are not tracked by `FileBasedMCPManager` (e.g. cloud-templated installs).
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pub fn spawn_root_for_installation(&self, uuid: Uuid) -> Option<PathBuf> {
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let hash = self.get_hash_by_uuid(uuid)?;
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let discovery_root = self
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.file_based_servers_by_root
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.iter()
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.filter(|(_, provider_map)| provider_map.values().any(|hashes| hashes.contains(&hash)))
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.map(|(root, _)| root.clone())
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.sorted()
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.next()?;
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// Global Warp installs live under `~/.warp/`, which is internal Warp state
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// rather than a meaningful working directory. Map them to the home dir so
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// all global installs (Warp and third-party) share a consistent cwd.
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if discovery_root == warp_data_dir() {
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return dirs::home_dir().or(Some(discovery_root));
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}
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Some(discovery_root)
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}
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}
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pub enum FileBasedMCPManagerEvent {
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@@ -560,6 +560,32 @@ mod tests {
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}
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}
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#[test]
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fn test_parse_cli_server_preserves_explicit_working_directory() {
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// An explicitly-set `working_directory` in a `.mcp.json`-style config must
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// round-trip into `CLIServer.cwd_parameter` so the file-based spawner does
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// not overwrite it with the discovery-root default.
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let json = r#"{
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"my-server": {
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"command": "node",
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"args": ["./tooling/mcp/server.js"],
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"working_directory": "/explicit/override/path"
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}
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}"#;
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let servers = MCPServer::from_user_json(json).expect("Failed to parse MCP servers");
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assert_eq!(servers.len(), 1);
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let TransportType::CLIServer(cli_server) = &servers[0].transport_type else {
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panic!("Expected CLIServer transport type");
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};
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assert_eq!(
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cli_server.cwd_parameter.as_deref(),
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Some("/explicit/override/path"),
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"Explicit working_directory must be preserved through parsing"
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);
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}
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#[test]
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fn test_parse_templatable_cli_server_without_args_and_resolve_json() {
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// Templatable MCP configs should work without an explicit "args" field.
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@@ -782,6 +782,20 @@ impl TemplatableMCPServerManager {
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value: execution_path,
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},
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);
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// For file-based MCP installations without an explicit `working_directory`,
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// default the spawn cwd to the directory the config was discovered in
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// (repo root for project-scoped configs, ~/.warp/ or ~ for globals). This
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// matches user expectations for repo-relative commands in `.mcp.json`.
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// Cloud-templated installations (lookup returns None) are unaffected and
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// continue to inherit Warp's process cwd.
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if cli_server.cwd_parameter.is_none() {
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if let Some(spawn_root) =
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FileBasedMCPManager::as_ref(ctx).spawn_root_for_installation(installation_uuid)
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{
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cli_server.cwd_parameter = Some(spawn_root.to_string_lossy().into_owned());
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}
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}
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}
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let executor = ctx.background_executor().clone();
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@@ -1742,6 +1756,11 @@ async fn spawn_server(
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}
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}
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// Capture the command and configured cwd for diagnostics before they're
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// moved into the Command builder closure.
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let command_for_log = command.clone();
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let cwd_for_log = cli_server.cwd_parameter.clone();
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// Try to spawn the child process.
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let (transport, stderr) = rmcp::transport::TokioChildProcess::builder(
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tokio::process::Command::new(command).configure(|cmd| {
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@@ -1768,6 +1787,17 @@ async fn spawn_server(
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.stderr(std::process::Stdio::piped())
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.spawn()
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.map_err(|err| {
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if err.kind() == std::io::ErrorKind::NotFound {
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let cwd_display = cwd_for_log
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.as_deref()
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.unwrap_or("<inherited from Warp's process cwd>");
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logger.log(format!(
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"[error] MCP: Failed to spawn '{server_name}': command '{command_for_log}' \
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not found (cwd: {cwd_display}). If your MCP server depends on a specific \
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working directory, set the `working_directory` field in your config to \
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override the default."
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));
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}
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rmcp::RmcpError::transport_creation::<rmcp::transport::TokioChildProcess>(err)
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})?;
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@@ -61,6 +61,24 @@ Check whether the target config file exists.
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}
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```
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By default, Warp spawns stdio servers from the directory the config was discovered in:
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- Project-scoped configs (`{repo_root}/.warp/.mcp.json`) run from the repo root.
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- Global configs (`~/.warp/.mcp.json`, `~/.claude.json`, etc.) run from the home directory.
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If the server's `command` or `args` are relative paths (e.g. `./tooling/mcp/server.js`) or the server expects a specific cwd, set `working_directory` to override the default:
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```json
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{
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"mcpServers": {
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"server-name": {
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"command": "node",
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"args": ["./tooling/mcp/server.js"],
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"working_directory": "/absolute/path/to/repo"
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}
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}
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}
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```
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### URL-based server (HTTP/SSE streaming transport)
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```json
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