test(e2e): add argv step spawn mode

Replace shell string steps with structured argv format in all e2e test
fixtures. Steps now use `argv` arrays instead of shell command strings,
with optional `comment` and `envs` fields:

```toml
# Simple:
steps = [["vt", "run", "build"]]

# With metadata:
steps = [{ argv = ["vt", "run", "test"], comment = "cache miss", envs = [["MY_ENV", "1"]] }]

# Stdin piping via vtt helper (no shell):
steps = [["vtt", "pipe-stdin", "from-stdin", "--", "vt", "run", "read-stdin"]]
```

Processes are spawned directly without a shell wrapper, avoiding shell
interference with signal handling and exit codes. Programs are resolved
from `CARGO_BIN_EXE_<name>` env vars. Shell redirects are replaced with
`vtt write-file` and `vtt pipe-stdin` helpers.

Also documents Conventional Commits format for PR titles in CLAUDE.md.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: branchseer

CLAUDE.md

@@ -38,6 +38,8 @@ just doc           # Documentation generation
 
 If `gt` (Graphite CLI) is available in PATH, use it instead of `gh` to create pull requests.
 
+PR titles must use [Conventional Commits](https://www.conventionalcommits.org) format: `type(scope): summary` (scope is optional), e.g. `feat(cache): add LRU eviction`, `fix: handle symlink loops`, `test(e2e): add ctrl-c propagation test`.
+
 ## Tests
 
 ```bash

Cargo.lock

@@ -36,8 +36,10 @@ pty_terminal = { workspace = true }
 pty_terminal_test = { workspace = true }
 regex = { workspace = true }
 serde = { workspace = true, features = ["derive", "rc"] }
+shell-escape = { workspace = true }
 tempfile = { workspace = true }
 toml = { workspace = true }
+vec1 = { workspace = true, features = ["serde"] }
 vite_path = { workspace = true, features = ["absolute-redaction"] }
 vite_workspace = { workspace = true }
 

crates/vite_task_bin/Cargo.toml

@@ -0,0 +1,7 @@
+pub fn run(args: &[String]) -> Result<(), Box<dyn std::error::Error>> {
+    if args.len() != 2 {
+        return Err("Usage: vtt cp <src> <dst>".into());
+    }
+    std::fs::copy(&args[0], &args[1])?;
+    Ok(())
+}

crates/vite_task_bin/src/vtt/cp.rs

@@ -8,20 +8,25 @@
 
 mod barrier;
 mod check_tty;
+mod cp;
+mod mkdir;
+mod pipe_stdin;
 mod print;
 mod print_cwd;
 mod print_env;
 mod print_file;
 mod read_stdin;
 mod replace_file_content;
+mod rm;
 mod touch_file;
+mod write_file;
 
 fn main() {
     let args: Vec<String> = std::env::args().collect();
     if args.len() < 2 {
         eprintln!("Usage: vtt <subcommand> [args...]");
         eprintln!(
-            "Subcommands: barrier, check-tty, print, print-cwd, print-env, print-file, read-stdin, replace-file-content, touch-file"
+            "Subcommands: barrier, check-tty, cp, mkdir, pipe-stdin, print, print-cwd, print-env, print-file, read-stdin, replace-file-content, rm, touch-file, write-file"
         );
         std::process::exit(1);
     }
@@ -32,6 +37,8 @@ fn main() {
             check_tty::run();
             Ok(())
         }
+        "cp" => cp::run(&args[2..]),
+        "mkdir" => mkdir::run(&args[2..]),
         "print" => {
             print::run(&args[2..]);
             Ok(())
@@ -41,7 +48,10 @@ fn main() {
         "print-file" => print_file::run(&args[2..]),
         "read-stdin" => read_stdin::run(),
         "replace-file-content" => replace_file_content::run(&args[2..]),
+        "pipe-stdin" => pipe_stdin::run(&args[2..]),
+        "rm" => rm::run(&args[2..]),
         "touch-file" => touch_file::run(&args[2..]),
+        "write-file" => write_file::run(&args[2..]),
         other => {
             eprintln!("Unknown subcommand: {other}");
             std::process::exit(1);

crates/vite_task_bin/src/vtt/main.rs

@@ -0,0 +1,21 @@
+pub fn run(args: &[String]) -> Result<(), Box<dyn std::error::Error>> {
+    let mut parents = false;
+    let mut paths = Vec::new();
+    for arg in args {
+        match arg.as_str() {
+            "-p" => parents = true,
+            _ => paths.push(arg.as_str()),
+        }
+    }
+    if paths.is_empty() {
+        return Err("Usage: vtt mkdir [-p] <path>...".into());
+    }
+    for path in paths {
+        if parents {
+            std::fs::create_dir_all(path)?;
+        } else {
+            std::fs::create_dir(path)?;
+        }
+    }
+    Ok(())
+}

crates/vite_task_bin/src/vtt/mkdir.rs

@@ -0,0 +1,33 @@
+/// pipe-stdin `<data>` -- `<command>` [`<args>`...]
+///
+/// Spawns `<command>` with `<data>` piped to its stdin, then exits with
+/// the child's exit code. If `<data>` is empty, an empty stdin is provided.
+pub fn run(args: &[String]) -> Result<(), Box<dyn std::error::Error>> {
+    let sep = args
+        .iter()
+        .position(|a| a == "--")
+        .ok_or("Usage: vtt pipe-stdin <data> -- <command> [args...]")?;
+    let data = &args[..sep].join(" ");
+    let cmd_args = &args[sep + 1..];
+    if cmd_args.is_empty() {
+        return Err("Usage: vtt pipe-stdin <data> -- <command> [args...]".into());
+    }
+
+    let mut child = std::process::Command::new(&cmd_args[0])
+        .args(&cmd_args[1..])
+        .stdin(std::process::Stdio::piped())
+        .spawn()?;
+
+    {
+        use std::io::Write;
+        let mut stdin = child.stdin.take().unwrap();
+        if !data.is_empty() {
+            stdin.write_all(data.as_bytes())?;
+        }
+        stdin.write_all(b"\n")?;
+        // stdin is closed when dropped, signaling EOF
+    }
+
+    let status = child.wait()?;
+    std::process::exit(status.code().unwrap_or(1));
+}

crates/vite_task_bin/src/vtt/pipe_stdin.rs

@@ -0,0 +1,22 @@
+pub fn run(args: &[String]) -> Result<(), Box<dyn std::error::Error>> {
+    let mut recursive = false;
+    let mut paths = Vec::new();
+    for arg in args {
+        match arg.as_str() {
+            "-r" | "-rf" | "-f" => recursive = true,
+            _ => paths.push(arg.as_str()),
+        }
+    }
+    if paths.is_empty() {
+        return Err("Usage: vtt rm [-rf] <path>...".into());
+    }
+    for path in paths {
+        let p = std::path::Path::new(path);
+        if p.is_dir() && recursive {
+            std::fs::remove_dir_all(p)?;
+        } else {
+            std::fs::remove_file(p)?;
+        }
+    }
+    Ok(())
+}

crates/vite_task_bin/src/vtt/rm.rs

@@ -0,0 +1,7 @@
+pub fn run(args: &[String]) -> Result<(), Box<dyn std::error::Error>> {
+    if args.len() < 2 {
+        return Err("Usage: vtt write-file <filename> <content>".into());
+    }
+    std::fs::write(&args[0], &args[1])?;
+    Ok(())
+}

crates/vite_task_bin/src/vtt/write_file.rs

@@ -3,8 +3,26 @@
 [[e2e]]
 name = "associate existing cache"
 steps = [
-  "vt run script1 # cache miss",
-  "vt run script2 # cache hit, same command as script1",
-  "vtt replace-file-content package.json '\"script2\": \"vtt print hello\"' '\"script2\": \"vtt print world\"' # change script2",
-  "vt run script2 # cache miss",
+  { argv = [
+    "vt",
+    "run",
+    "script1",
+  ], comment = "cache miss" },
+  { argv = [
+    "vt",
+    "run",
+    "script2",
+  ], comment = "cache hit, same command as script1" },
+  { argv = [
+    "vtt",
+    "replace-file-content",
+    "package.json",
+    "\"script2\": \"vtt print hello\"",
+    "\"script2\": \"vtt print world\"",
+  ], comment = "change script2" },
+  { argv = [
+    "vt",
+    "run",
+    "script2",
+  ], comment = "cache miss" },
 ]