feat: show task list when vp run is called without arguments

Instead of a clap usage error, `vp run` now loads the task graph and
prints all available tasks grouped by current package vs other packages.
When `vp run` appears inside a task script, it falls back to a synthetic
plan request so it executes as a normal process.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: branchseer

crates/vite_task/src/cli/mod.rs

@@ -15,8 +15,8 @@ pub enum CacheSubcommand {
 /// Arguments for the `run` subcommand.
 #[derive(Debug, clap::Args)]
 pub struct RunCommand {
-    /// `packageName#taskName` or `taskName`.
-    pub task_specifier: TaskSpecifier,
+    /// `packageName#taskName` or `taskName`. If omitted, lists all available tasks.
+    pub task_specifier: Option<TaskSpecifier>,
 
     /// Run tasks found in all packages in the workspace, in topological order based on package dependencies.
     #[clap(default_value = "false", short, long)]
@@ -49,6 +49,9 @@ pub enum Command {
 
 #[derive(thiserror::Error, Debug)]
 pub enum CLITaskQueryError {
+    #[error("no task specifier provided")]
+    MissingTaskSpecifier,
+
     #[error("--recursive and --transitive cannot be used together")]
     RecursiveTransitiveConflict,
 
@@ -70,6 +73,8 @@ impl RunCommand {
         let Self { task_specifier, recursive, transitive, ignore_depends_on, additional_args } =
             self;
 
+        let task_specifier = task_specifier.ok_or(CLITaskQueryError::MissingTaskSpecifier)?;
+
         let include_explicit_deps = !ignore_depends_on;
 
         let query_kind = if recursive {

crates/vite_task/src/session/mod.rs

@@ -101,7 +101,15 @@ impl vite_task_plan::PlanRequestParser for PlanRequestParser<'_> {
                 Command::Cache { .. } => Ok(Some(PlanRequest::Synthetic(
                     command.to_synthetic_plan_request(UserCacheConfig::disabled()),
                 ))),
-                Command::Run(run_command) => Ok(Some(run_command.into_plan_request(&command.cwd)?)),
+                Command::Run(run_command) => match run_command.into_plan_request(&command.cwd) {
+                    Ok(plan_request) => Ok(Some(plan_request)),
+                    Err(crate::cli::CLITaskQueryError::MissingTaskSpecifier) => {
+                        Ok(Some(PlanRequest::Synthetic(
+                            command.to_synthetic_plan_request(UserCacheConfig::disabled()),
+                        )))
+                    }
+                    Err(err) => Err(err.into()),
+                },
             },
             HandledCommand::Verbatim => Ok(None),
         }
@@ -220,13 +228,19 @@ impl<'a> Session<'a> {
             Command::Cache { ref subcmd } => self.handle_cache_command(subcmd),
             Command::Run(run_command) => {
                 let cwd = Arc::clone(&self.cwd);
-                let plan = self.plan_from_cli(cwd, run_command).await?;
-                let reporter = LabeledReporter::new(std::io::stdout(), self.workspace_path());
-                Ok(self
-                    .execute(plan, Box::new(reporter))
-                    .await
-                    .err()
-                    .unwrap_or(ExitStatus::SUCCESS))
+                match self.plan_from_cli(cwd, run_command).await {
+                    Ok(plan) => {
+                        let reporter =
+                            LabeledReporter::new(std::io::stdout(), self.workspace_path());
+                        Ok(self
+                            .execute(plan, Box::new(reporter))
+                            .await
+                            .err()
+                            .unwrap_or(ExitStatus::SUCCESS))
+                    }
+                    Err(err) if err.is_missing_task_specifier() => self.print_task_list().await,
+                    Err(err) => Err(err.into()),
+                }
             }
         }
     }
@@ -242,6 +256,63 @@ impl<'a> Session<'a> {
         }
     }
 
+    #[expect(
+        clippy::future_not_send,
+        reason = "session is single-threaded, futures do not need to be Send"
+    )]
+    async fn print_task_list(&mut self) -> anyhow::Result<ExitStatus> {
+        use std::io::Write;
+
+        let cwd = Arc::clone(&self.cwd);
+        let task_graph = self.ensure_task_graph_loaded().await?;
+        let mut entries = task_graph.list_tasks();
+        entries.sort_unstable_by(|a, b| {
+            a.task_display
+                .package_name
+                .cmp(&b.task_display.package_name)
+                .then_with(|| a.task_display.task_name.cmp(&b.task_display.task_name))
+        });
+
+        // Find the most specific package containing the CWD (longest matching path)
+        let current_package_path = entries
+            .iter()
+            .map(|e| &e.task_display.package_path)
+            .filter(|p| cwd.as_path().starts_with(p.as_path()))
+            .max_by_key(|p| p.as_path().as_os_str().len());
+
+        let (current, others): (Vec<_>, Vec<_>) = entries
+            .iter()
+            .partition(|e| current_package_path == Some(&e.task_display.package_path));
+
+        let mut stdout = std::io::stdout().lock();
+
+        if !current.is_empty() {
+            let package_name = &current[0].task_display.package_name;
+            if package_name.is_empty() {
+                writeln!(stdout, "Tasks in the current package")?;
+            } else {
+                writeln!(stdout, "Tasks in the current package ({package_name})")?;
+            }
+            for entry in &current {
+                writeln!(stdout, "  {}", entry.task_display.task_name)?;
+                writeln!(stdout, "    {}", entry.command)?;
+            }
+        }
+
+        if !others.is_empty() {
+            if !current.is_empty() {
+                writeln!(stdout)?;
+            }
+            writeln!(stdout, "Tasks in other packages")?;
+            for entry in &others {
+                writeln!(stdout, "  {}", entry.task_display)?;
+                writeln!(stdout, "    {}", entry.command)?;
+            }
+        }
+
+        Ok(ExitStatus::SUCCESS)
+    }
+
     /// Lazily initializes and returns the execution cache.
     /// The cache is only created when first accessed to avoid `SQLite` race conditions
     /// when multiple processes start simultaneously.
@@ -320,15 +391,21 @@ impl<'a> Session<'a> {
         cwd: Arc<AbsolutePath>,
         command: RunCommand,
     ) -> Result<ExecutionPlan, vite_task_plan::Error> {
-        let plan_request = command.into_plan_request(&cwd).map_err(|error| {
-            TaskPlanErrorKind::ParsePlanRequestError {
-                error: error.into(),
-                program: Str::from("vp"),
-                args: Arc::default(),
-                cwd: Arc::clone(&cwd),
+        let plan_request = match command.into_plan_request(&cwd) {
+            Ok(plan_request) => plan_request,
+            Err(crate::cli::CLITaskQueryError::MissingTaskSpecifier) => {
+                return Err(TaskPlanErrorKind::MissingTaskSpecifier.with_empty_call_stack());
+            }
+            Err(error) => {
+                return Err(TaskPlanErrorKind::ParsePlanRequestError {
+                    error: error.into(),
+                    program: Str::from("vp"),
+                    args: Arc::default(),
+                    cwd: Arc::clone(&cwd),
+                }
+                .with_empty_call_stack());
             }
-            .with_empty_call_stack()
-        })?;
+        };
         let plan = ExecutionPlan::plan(
             plan_request,
             &self.workspace_path,

crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list/package.json

@@ -0,0 +1,4 @@
+{
+  "name": "task-list-test",
+  "private": true
+}

crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list/packages/app/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "app",
+  "scripts": {
+    "build": "echo build app",
+    "test": "echo test app"
+  },
+  "dependencies": {
+    "lib": "workspace:*"
+  }
+}

crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list/packages/app/vite-task.json

@@ -0,0 +1,9 @@
+{
+  "tasks": {
+    "build": {},
+    "test": {},
+    "lint": {
+      "command": "echo lint app"
+    }
+  }
+}

crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list/packages/lib/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "lib",
+  "scripts": {
+    "build": "echo build lib"
+  }
+}

crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list/packages/lib/vite-task.json

@@ -0,0 +1,5 @@
+{
+  "tasks": {
+    "build": {}
+  }
+}

crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list/pnpm-workspace.yaml

@@ -0,0 +1,2 @@
+packages:
+  - packages/*

crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list/snapshots.toml

@@ -0,0 +1,18 @@
+[[e2e]]
+name = "list tasks from package dir"
+cwd = "packages/app"
+steps = [
+  "vp run",
+]
+
+[[e2e]]
+name = "list tasks from workspace root"
+steps = [
+  "vp run",
+]
+
+[[e2e]]
+name = "vp run in script"
+steps = [
+  "vp run list-tasks",
+]

crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list/snapshots/list tasks from package dir.snap

@@ -0,0 +1,21 @@
+---
+source: crates/vite_task_bin/tests/e2e_snapshots/main.rs
+expression: e2e_outputs
+input_file: crates/vite_task_bin/tests/e2e_snapshots/fixtures/task-list
+---
+> vp run
+Tasks in the current package (app)
+  build
+    echo build app
+  lint
+    echo lint app
+  test
+    echo test app
+
+Tasks in other packages
+  lib#build
+    echo build lib
+  task-list-test#hello
+    echo hello from root
+  task-list-test#list-tasks
+    vp run