refinements based on feedback

Cargo.lock

@@ -38,7 +38,7 @@ version = "1.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "40c48f72fd53cd289104fc64099abca73db4166ad86ea0b4341abe65af83dadc"
 dependencies = [
- "windows-sys",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -49,7 +49,7 @@ checksum = "291e6a250ff86cd4a820112fb8898808a366d8f9f58ce16d1f538353ad55747d"
 dependencies = [
  "anstyle",
  "once_cell_polyfill",
- "windows-sys",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -63,6 +63,18 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "bitflags"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
+
+[[package]]
+name = "bitflags"
+version = "2.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "843867be96c8daad0d758b57df9392b6d8d271134fce549de6ce169ff98a92af"
+
 [[package]]
 name = "block-buffer"
 version = "0.10.4"
@@ -155,7 +167,7 @@ version = "3.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "faf9468729b8cbcea668e36183cb69d317348c2e08e994829fb56ebfdfbaac34"
 dependencies = [
- "windows-sys",
+ "windows-sys 0.61.2",
 ]
 
 [[package]]
@@ -193,6 +205,15 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "877a4ace8713b0bcf2a4e7eec82529c029f1d0619886d18145fea96c3ffe5c0f"
 
+[[package]]
+name = "fsevent-sys"
+version = "4.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "76ee7a02da4d231650c7cea31349b889be2f45ddb3ef3032d2ec8185f6313fd2"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "generic-array"
 version = "0.14.7"
@@ -237,6 +258,26 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "inotify"
+version = "0.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bd5b3eaf1a28b758ac0faa5a4254e8ab2705605496f1b1f3fbbc3988ad73d199"
+dependencies = [
+ "bitflags 2.11.0",
+ "inotify-sys",
+ "libc",
+]
+
+[[package]]
+name = "inotify-sys"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e05c02b5e89bff3b946cedeca278abc628fe811e604f027c45a8aa3cf793d0eb"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "is_terminal_polyfill"
 version = "1.70.2"
@@ -249,18 +290,83 @@ version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
 
+[[package]]
+name = "kqueue"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eac30106d7dce88daf4a3fcb4879ea939476d5074a9b7ddd0fb97fa4bed5596a"
+dependencies = [
+ "kqueue-sys",
+ "libc",
+]
+
+[[package]]
+name = "kqueue-sys"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed9625ffda8729b85e45cf04090035ac368927b8cebc34898e7c120f52e4838b"
+dependencies = [
+ "bitflags 1.3.2",
+ "libc",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.183"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b5b646652bf6661599e1da8901b3b9522896f01e736bad5f723fe7a3a27f899d"
 
+[[package]]
+name = "log"
+version = "0.4.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
+
 [[package]]
 name = "memchr"
 version = "2.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8ca58f447f06ed17d5fc4043ce1b10dd205e060fb3ce5b979b8ed8e59ff3f79"
 
+[[package]]
+name = "mio"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a69bcab0ad47271a0234d9422b131806bf3968021e5dc9328caf2d4cd58557fc"
+dependencies = [
+ "libc",
+ "log",
+ "wasi",
+ "windows-sys 0.61.2",
+]
+
+[[package]]
+name = "notify"
+version = "8.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4d3d07927151ff8575b7087f245456e549fea62edf0ec4e565a5ee50c8402bc3"
+dependencies = [
+ "bitflags 2.11.0",
+ "fsevent-sys",
+ "inotify",
+ "kqueue",
+ "libc",
+ "log",
+ "mio",
+ "notify-types",
+ "walkdir",
+ "windows-sys 0.60.2",
+]
+
+[[package]]
+name = "notify-types"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42b8cfee0e339a0337359f3c88165702ac6e600dc01c0cc9579a92d62b08477a"
+dependencies = [
+ "bitflags 2.11.0",
+]
+
 [[package]]
 name = "once_cell_polyfill"
 version = "1.70.2"
@@ -276,6 +382,7 @@ dependencies = [
  "clap_complete_nushell",
  "colored",
  "glob",
+ "notify",
  "serde",
  "serde_json",
  "sha256",
@@ -306,6 +413,15 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "same-file"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
+dependencies = [
+ "winapi-util",
+]
+
 [[package]]
 name = "serde"
 version = "1.0.228"
@@ -472,12 +588,46 @@ version = "0.9.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
 
+[[package]]
+name = "walkdir"
+version = "2.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "29790946404f91d9c5d06f9874efddea1dc06c5efe94541a7d6863108e3a5e4b"
+dependencies = [
+ "same-file",
+ "winapi-util",
+]
+
+[[package]]
+name = "wasi"
+version = "0.11.1+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ccf3ec651a847eb01de73ccad15eb7d99f80485de043efb2f370cd654f4ea44b"
+
+[[package]]
+name = "winapi-util"
+version = "0.1.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2a7b1c03c876122aa43f3020e6c3c3ee5c05081c9a00739faf7503aeba10d22"
+dependencies = [
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "windows-link"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
 
+[[package]]
+name = "windows-sys"
+version = "0.60.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2f500e4d28234f72040990ec9d39e3a6b950f9f22d3dba18416c35882612bcb"
+dependencies = [
+ "windows-targets",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.61.2"
@@ -487,6 +637,71 @@ dependencies = [
  "windows-link",
 ]
 
+[[package]]
+name = "windows-targets"
+version = "0.53.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4945f9f551b88e0d65f3db0bc25c33b8acea4d9e41163edf90dcd0b19f9069f3"
+dependencies = [
+ "windows-link",
+ "windows_aarch64_gnullvm",
+ "windows_aarch64_msvc",
+ "windows_i686_gnu",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc",
+ "windows_x86_64_gnu",
+ "windows_x86_64_gnullvm",
+ "windows_x86_64_msvc",
+]
+
+[[package]]
+name = "windows_aarch64_gnullvm"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a9d8416fa8b42f5c947f8482c43e7d89e73a173cead56d044f6a56104a6d1b53"
+
+[[package]]
+name = "windows_aarch64_msvc"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9d782e804c2f632e395708e99a94275910eb9100b2114651e04744e9b125006"
+
+[[package]]
+name = "windows_i686_gnu"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "960e6da069d81e09becb0ca57a65220ddff016ff2d6af6a223cf372a506593a3"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fa7359d10048f68ab8b09fa71c3daccfb0e9b559aed648a8f95469c27057180c"
+
+[[package]]
+name = "windows_i686_msvc"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e7ac75179f18232fe9c285163565a57ef8d3c89254a30685b57d83a38d326c2"
+
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c3842cdd74a865a8066ab39c8a7a473c0778a3f29370b5fd6b4b9aa7df4a499"
+
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ffa179e2d07eee8ad8f57493436566c7cc30ac536a3379fdf008f47f6bb7ae1"
+
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d6bbff5f0aada427a1e5a6da5f1f98158182f26556f345ac9e04d36d0ebed650"
+
 [[package]]
 name = "winnow"
 version = "1.0.0"

Cargo.toml

@@ -10,6 +10,7 @@ clap_complete = "4.6.0"
 clap_complete_nushell = "4.6.0"
 colored = "3.1.1"
 glob = "0.3.3"
+notify = "8.2.0"
 serde = { version = "1.0.228", features = ["derive"] }
 serde_json = "1.0.149"
 sha256 = "1.6.0"

src/app.rs

@@ -60,6 +60,14 @@ enum Subcommand {
         /// The package to be added
         package: String,
     },
+    /// Watches for source code changes and triggers a recompilation && re-run on change
+    Watch {
+        /// The build mode to use
+        mode: Option<String>,
+        /// Arguments to pass to the project binary
+        #[arg(long, short)]
+        args: Option<Vec<String>>,
+    },
 }
 
 #[derive(clap::Subcommand)]
@@ -186,8 +194,153 @@ impl App {
                     std::process::exit(1);
                 }
             }
+            Subcommand::Watch { mode, args } => {
+                if let Err(e) = watch(&mode, args) {
+                    eprintln!("Error running watch: {e}");
+                    std::process::exit(1);
                 }
             }
+        }
+    }
+}
+
+fn watch(mode: &Option<String>, args: Option<Vec<String>>) -> std::io::Result<()> {
+    use std::io::Write;
+
+    // save terminal state
+    let mut stdout = std::io::stdout();
+    // enter alternate screen — this is a separate terminal buffer,
+    // exiting it restores everything exactly as it was
+    write!(stdout, "\x1b[?1049h")?;
+    stdout.flush()?;
+
+    // make sure we always restore the terminal, even on panic
+    let result = watch_inner(mode, args);
+
+    // exit alternate screen
+    write!(stdout, "\x1b[?1049l")?;
+    stdout.flush()?;
+
+    result
+}
+
+fn watch_inner(mode: &Option<String>, args: Option<Vec<String>>) -> std::io::Result<()> {
+    use notify::{Event, RecursiveMode, Watcher, recommended_watcher};
+    use std::io::Write;
+    use std::sync::mpsc;
+    use std::time::{Duration, Instant};
+
+    let clear = || {
+        let mut stdout = std::io::stdout();
+        write!(stdout, "\x1b[2J\x1b[H").ok();
+        stdout.flush().ok();
+    };
+
+    let print_header = |label: &str| {
+        println!(
+            "  {} project (ctrl+c to stop) — {label}",
+            "Watching".green().bold()
+        );
+        println!("{}", "─".repeat(50).dimmed());
+    };
+
+    // track the running child process
+    let mut child: Option<std::process::Child> = None;
+
+    let kill_child = |child: &mut Option<std::process::Child>| {
+        if let Some(c) = child {
+            c.kill().ok();
+            c.wait().ok();
+        }
+        *child = None;
+    };
+
+    let run_child = |mode: &Option<String>,
+                     args: &Option<Vec<String>>|
+     -> std::io::Result<std::process::Child> {
+        let conf = get_config().ok_or(std::io::Error::new(
+            std::io::ErrorKind::NotFound,
+            "no Pallet.toml found",
+        ))?;
+        let build_config = conf.get_or_default(mode).ok_or(std::io::Error::new(
+            std::io::ErrorKind::NotFound,
+            "build layout not found",
+        ))?;
+        let mut command = Command::new(format!("target/{}/{}", build_config.name, conf.name));
+        if let Some(a) = args {
+            for arg in a {
+                command.arg(arg);
+            }
+        }
+        command
+            .spawn()
+            .map_err(|e| std::io::Error::other(format!("{e}")))
+    };
+
+    // initial build + run
+    clear();
+    print_header("starting");
+    if build(mode, false).is_ok() {
+        child = run_child(mode, &args).ok();
+    }
+
+    let (tx, rx) = mpsc::channel::<notify::Result<Event>>();
+    let mut watcher = recommended_watcher(tx).map_err(|e| std::io::Error::other(format!("{e}")))?;
+    watcher
+        .watch(Path::new("src"), RecursiveMode::Recursive)
+        .map_err(|e| std::io::Error::other(format!("{e}")))?;
+
+    let mut last_build = Instant::now()
+        .checked_sub(Duration::from_secs(1))
+        .unwrap_or(Instant::now());
+
+    loop {
+        match rx.recv() {
+            Ok(Ok(event)) => {
+                let is_relevant = matches!(
+                    event.kind,
+                    notify::EventKind::Create(_)
+                        | notify::EventKind::Modify(_)
+                        | notify::EventKind::Remove(_)
+                );
+                let affects_source = event.paths.iter().any(|p| {
+                    matches!(
+                        p.extension().and_then(|e| e.to_str()),
+                        Some("c") | Some("h")
+                    )
+                });
+                let debounced = last_build.elapsed() > Duration::from_millis(500);
+
+                if is_relevant && affects_source && debounced {
+                    last_build = Instant::now();
+
+                    // kill whatever is currently running
+                    kill_child(&mut child);
+
+                    clear();
+                    print_header("rebuilding");
+
+                    match build(mode, false) {
+                        Ok(_) => {
+                            child = run_child(mode, &args).ok();
+                        }
+                        Err(e) => {
+                            eprintln!("  {} {e}", "Error".red().bold());
+                            // child stays None until next successful build
+                        }
+                    }
+                }
+            }
+            Ok(Err(e)) => eprintln!("  {} watch error: {e}", "Error".red().bold()),
+            Err(e) => {
+                eprintln!("  {} channel error: {e}", "Error".red().bold());
+                break;
+            }
+        }
+    }
+
+    kill_child(&mut child);
+    Ok(())
 }
 
 fn add_package(package: &str) -> std::io::Result<()> {