feat(e2e): detect [send-me-ctrl-c] and send SIGINT to process

Implement automatic Ctrl+C detection in e2e tests to enable testing of
interrupted task behavior and cache invalidation.

Changes:
- Add send_ctrlc dependency with tokio feature for cross-platform SIGINT support
- Update test runner to spawn processes with spawn_interruptible()
- Detect [send-me-ctrl-c] magic string in stdout and send SIGINT
- Add new e2e test case verifying "cache not updated: execution interrupted"

Test Details:
- ctrl-c-interruption fixture with Node.js script that handles SIGINT gracefully
- Script prints magic string, then waits indefinitely for signal
- Test verifies both runs show cache miss (proving cache wasn't saved)
- Process exits with code 0 after receiving SIGINT

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: branchseer

Cargo.lock

@@ -26,6 +26,7 @@ copy_dir = { workspace = true }
 cow-utils = { workspace = true }
 insta = { workspace = true, features = ["glob", "json", "redactions", "filters", "ron"] }
 regex = { workspace = true }
+send_ctrlc = { version = "0.6.0", features = ["tokio"] }
 serde = { workspace = true, features = ["derive", "rc"] }
 tempfile = { workspace = true }
 toml = { workspace = true }

crates/vite_task_bin/Cargo.toml

@@ -0,0 +1,12 @@
+// Handle SIGINT gracefully
+process.on('SIGINT', () => {
+  console.log('Received SIGINT, exiting gracefully');
+  process.exit(0);
+});
+
+// Print magic string to trigger Ctrl+C
+console.log('[send-me-ctrl-c]');
+
+// Keep the process alive to receive SIGINT
+// (process will be interrupted by the test infrastructure)
+setInterval(() => {}, 1000);

crates/vite_task_bin/tests/e2e_snapshots/fixtures/ctrl-c-interruption/interrupt-test.js

@@ -0,0 +1,6 @@
+{
+  "name": "ctrl-c-interruption",
+  "scripts": {
+    "interrupt-test": "node interrupt-test.js"
+  }
+}

crates/vite_task_bin/tests/e2e_snapshots/fixtures/ctrl-c-interruption/package.json

@@ -0,0 +1,6 @@
+[[e2e]]
+name = "interrupted task does not update cache"
+steps = [
+  "vite run interrupt-test",
+  "vite run interrupt-test",
+]

crates/vite_task_bin/tests/e2e_snapshots/fixtures/ctrl-c-interruption/snapshots.toml

@@ -0,0 +1,45 @@
+---
+source: crates/vite_task_bin/tests/e2e_snapshots/main.rs
+assertion_line: 309
+expression: e2e_outputs
+input_file: crates/vite_task_bin/tests/e2e_snapshots/fixtures/ctrl-c-interruption
+---
+> vite run interrupt-test
+$ node interrupt-test.js
+[send-me-ctrl-c]
+Received SIGINT, exiting gracefully
+
+
+━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+    Vite+ Task Runner • Execution Summary
+━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+Statistics:   1 tasks • 0 cache hits • 1 cache misses 
+Performance:  0% cache hit rate
+
+Task Details:
+────────────────────────────────────────────────
+  [1] ctrl-c-interruption#interrupt-test: $ node interrupt-test.js ✓
+      → Cache miss: no previous cache entry found
+      → Cache not updated: execution interrupted
+━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+> vite run interrupt-test
+$ node interrupt-test.js
+[send-me-ctrl-c]
+Received SIGINT, exiting gracefully
+
+
+━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+    Vite+ Task Runner • Execution Summary
+━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
+
+Statistics:   1 tasks • 0 cache hits • 1 cache misses 
+Performance:  0% cache hit rate
+
+Task Details:
+────────────────────────────────────────────────
+  [1] ctrl-c-interruption#interrupt-test: $ node interrupt-test.js ✓
+      → Cache miss: no previous cache entry found
+      → Cache not updated: execution interrupted
+━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

crates/vite_task_bin/tests/e2e_snapshots/fixtures/ctrl-c-interruption/snapshots/interrupted task does not update cache.snap

@@ -11,6 +11,7 @@ use std::{
 
 use copy_dir::copy_dir;
 use redact::redact_e2e_output;
+use send_ctrlc::{Interruptible as _, InterruptibleCommand as _};
 use tokio::{
     io::{AsyncReadExt, AsyncWriteExt},
     process::Command,
@@ -193,7 +194,7 @@ async fn run_case_inner(tmpdir: &AbsolutePath, fixture_path: &Path, fixture_name
             cmd.stdout(Stdio::piped());
             cmd.stderr(Stdio::piped());
 
-            let mut child = cmd.spawn().unwrap();
+            let mut child = cmd.spawn_interruptible().unwrap();
 
             // Write stdin if provided, then close it
             if let Some(stdin_content) = step.stdin() {
@@ -210,6 +211,10 @@ async fn run_case_inner(tmpdir: &AbsolutePath, fixture_path: &Path, fixture_name
             let mut stdout_buf = Vec::new();
             let mut stderr_buf = Vec::new();
 
+            // Magic string detection
+            const MAGIC_STRING: &[u8] = b"[send-me-ctrl-c]";
+            let mut ctrl_c_sent = false;
+
             // Read chunks concurrently with process wait, using select! with timeout
             let mut stdout_done = false;
             let mut stderr_done = false;
@@ -232,7 +237,16 @@ async fn run_case_inner(tmpdir: &AbsolutePath, fixture_path: &Path, fixture_name
                     result = stdout_handle.read(&mut stdout_chunk), if !stdout_done => {
                         match result {
                             Ok(0) => stdout_done = true,
-                            Ok(n) => stdout_buf.extend_from_slice(&stdout_chunk[..n]),
+                            Ok(n) => {
+                                let chunk = &stdout_chunk[..n];
+                                stdout_buf.extend_from_slice(chunk);
+
+                                // Check if accumulated stdout buffer contains magic string
+                                if !ctrl_c_sent && stdout_buf.windows(MAGIC_STRING.len()).any(|w| w == MAGIC_STRING) {
+                                    ctrl_c_sent = true;
+                                    let _ = child.interrupt();
+                                }
+                            }
                             Err(_) => stdout_done = true,
                         }
                     }