chore: Release galdr version 0.2.4

The process callback filled the whole mapped buffer every cycle. PipeWire
sizes that buffer by clock.quantum-limit (8192 frames by default) while the
graph drives galdr at the 256-frame quantum we ask for, so each cycle did
~32x the work and everything past the quantum was dropped: choppy output,
constant deadline misses in pw-top, and envelopes that sounded 32x faster
than their settings. Use Buffer::requested (pipewire feature v0_3_49),
clamped to the buffer, with the --latency value as fallback.

tui: typing a glyph no longer advances the cursor to the right.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

.gitea/workflows/release.yml

@@ -25,7 +25,7 @@ jobs:
     runs-on: ${{ matrix.runs-on }}
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: builtin:checkout
 
       - name: Install Rust stable
         uses: dtolnay/rust-toolchain@stable
@@ -40,11 +40,16 @@ jobs:
           echo "RUSTC_WRAPPER=sccache" >> "$GITHUB_ENV"
           echo "SCCACHE_DIR=${{ matrix.sccache_dir }}" >> "$GITHUB_ENV"
           mkdir -p "${{ matrix.sccache_dir }}"
-          if ! command -v sccache >/dev/null 2>&1; then
+          if command -v sccache >/dev/null 2>&1; then sccache --version; exit 0; fi
-            V=0.8.2
+          # Bare runners (aarch64 = klokka host) are pre-provisioned; CI must not
-            curl -sSL "https://github.com/mozilla/sccache/releases/download/v${V}/sccache-v${V}-x86_64-unknown-linux-musl.tar.gz" | tar -xz
+          # install onto them (and this tarball is x86_64-only). Only the
-            sudo install -m0755 "sccache-v${V}-x86_64-unknown-linux-musl/sccache" /usr/local/bin/sccache
+          # ephemeral x86_64 container installs; a bare host missing it fails loud.
+          if [ "${{ matrix.arch }}" != x86_64 ]; then
+            echo "::error::sccache missing on the bare ${{ matrix.arch }} runner — provision klokka; CI must not install on bare hosts"; exit 1
           fi
+          V=0.8.2
+          curl -sSL "https://github.com/mozilla/sccache/releases/download/v${V}/sccache-v${V}-x86_64-unknown-linux-musl.tar.gz" | tar -xz
+          sudo install -m0755 "sccache-v${V}-x86_64-unknown-linux-musl/sccache" /usr/local/bin/sccache
           sccache --version
 
       - name: Ensure build deps (libpipewire for output, alsa for MIDI, clang for bindgen)
@@ -67,6 +72,9 @@ jobs:
             echo "bare runner already has libpipewire + alsa + clang"
           fi
 
+      - name: Test
+        run: cargo test --release --locked --target ${{ matrix.target }}
+
       - name: Build
         run: cargo build --release --locked --target ${{ matrix.target }}
 
@@ -120,7 +128,7 @@ jobs:
     runs-on: aarch64
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: builtin:checkout
 
       - name: Compute checksums and update PKGBUILD
         run: |

Cargo.lock

@@ -320,7 +320,7 @@ dependencies = [
 
 [[package]]
 name = "galdr"
-version = "0.2.1"
+version = "0.2.4"
 dependencies = [
  "anyhow",
  "arc-swap",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "galdr"
-version = "0.2.1"
+version = "0.2.4"
 edition = "2021"
 description = "A terminal grid synthesizer: signal flows spatially through single-glyph unit generators, voiced by MIDI, rendered low-latency to PipeWire"
 license = "MIT"
@@ -11,7 +11,7 @@ codegen-units = 1
 
 [dependencies]
 anyhow = "1"
-pipewire = "0.10"
+pipewire = { version = "0.10", features = ["v0_3_49"] } # Buffer::requested
 midir = "0.10"
 arc-swap = "1.7"
 rtrb = "0.3"

README.md

@@ -59,7 +59,10 @@ galdr [--latency <frames>] [--poly <n>] [--rate <hz>] [--midi-name <s>]
 
 galdr creates a virtual MIDI input port named **galdr**; connect orca or any
 sequencer/DAW to it. `--midi-name` connects to an existing port instead.
-Cursor keys move; type a glyph to place it; Backspace clears; Esc quits.
+
+Keys: cursor keys move; type a glyph to place it; Backspace clears; `?` toggles
+help; Esc quits. Resize the grid with `(` / `)` (width) and `_` / `+` (height)
+by one ruler division, or Ctrl+arrows by one cell (orca's bindings).
 
 Runtime deps: PipeWire and ALSA (MIDI). Built in Rust; reuses the native
 PipeWire path from spectrust.

aur/PKGBUILD

@@ -1,6 +1,6 @@
 # Maintainer: Bendik Aagaard Lynghaug <bendik.lynghaug@gmail.com>
 pkgname=galdr
-pkgver=0.2.1
+pkgver=0.2.4
 pkgrel=1
 pkgdesc="Terminal grid synthesizer: signal flows through single-glyph unit generators, MIDI in, low-latency PipeWire out"
 arch=('x86_64' 'aarch64')

src/audio.rs

@@ -75,6 +75,7 @@ fn run(
         .add_local_listener_with_user_data(())
         .process(move |stream, _| {
             let Some(mut buffer) = stream.dequeue_buffer() else { return };
+            let requested = buffer.requested() as usize;
             let datas = buffer.datas_mut();
             let Some(data) = datas.first_mut() else { return };
             let stride = ch * 4;
@@ -85,9 +86,15 @@ fn run(
                 engine.apply(ev);
             }
 
+            // Render only what the graph asked for this cycle. The mapped
+            // buffer is sized by clock.quantum-limit (8192 frames by default),
+            // so filling it whole would do ~32x the work of a 256-frame
+            // quantum and PipeWire would drop everything past the quantum:
+            // choppy output and envelopes that race through their stages.
+            let want = if requested > 0 { requested } else { latency as usize };
             let mut n_frames = 0usize;
             if let Some(slice) = data.data() {
-                n_frames = slice.len() / stride;
+                n_frames = want.min(slice.len() / stride);
                 for f in 0..n_frames {
                     let smp = engine.render(&program);
                     let bytes = smp.to_le_bytes();

src/dsp.rs

@@ -9,7 +9,7 @@
 //! params, lowercase a-z read MIDI CC (a = CC 0). A neighbour to the left/right
 //! supplies a parameter; `M` instead reads the left cell as a second signal.
 
-use crate::grid::{Grid, H, SLOTS, W};
+use crate::grid::{Grid, MAX_W, SLOTS};
 
 pub const MAX_STATE: usize = 4 * SLOTS;
 pub const TAU: f32 = std::f32::consts::TAU;
@@ -110,20 +110,23 @@ pub fn compile(grid: &Grid) -> Program {
     let mut nodes = Vec::new();
     let mut st = 0usize;
     let mut has_env = false;
-    for row in 0..H {
+    for row in 0..grid.h {
-        for col in 0..W {
+        for col in 0..grid.w {
             let Some((op, ssize)) = op_of(grid.get(col, row)) else { continue };
             if matches!(op, Op::Env) {
                 has_env = true;
             }
-            let input =
+            let input = if row > 0 && occupied(grid.get(col, row - 1)) {
-                if row > 0 && occupied(grid.get(col, row - 1)) { Some((row - 1) * W + col) } else { None };
+                Some((row - 1) * MAX_W + col)
-            let lsig = if col > 0 { Some(row * W + col - 1) } else { None };
+            } else {
+                None
+            };
+            let lsig = if col > 0 { Some(row * MAX_W + col - 1) } else { None };
             let left = if col > 0 { param_of(grid.get(col - 1, row)) } else { Param::None };
-            let right = if col + 1 < W { param_of(grid.get(col + 1, row)) } else { Param::None };
+            let right = if col + 1 < grid.w { param_of(grid.get(col + 1, row)) } else { Param::None };
             let this_st = st;
             st = (st + ssize).min(MAX_STATE - 4);
-            nodes.push(Node { op, out: row * W + col, input, lsig, left, right, st: this_st });
+            nodes.push(Node { op, out: row * MAX_W + col, input, lsig, left, right, st: this_st });
         }
     }
     Program { nodes, has_env }
@@ -299,3 +302,136 @@ pub fn eval_voice(v: &mut Voice, p: &Program, regs: &[f32], sr: f32) -> f32 {
     v.env_level = env_max;
     out
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::grid::Grid;
+
+    fn grid_from(src: &str) -> Grid {
+        let mut g = Grid::new();
+        for (r, line) in src.lines().enumerate() {
+            for (c, ch) in line.chars().enumerate() {
+                g.set(c, r, ch);
+            }
+        }
+        g
+    }
+
+    fn voice(freq: f32, gate: f32, vel: f32) -> Voice {
+        let mut v = Voice::new();
+        v.active = true;
+        v.freq = freq;
+        v.gate = gate;
+        v.vel = vel;
+        v
+    }
+
+    fn render(v: &mut Voice, p: &Program, n: usize) -> Vec<f32> {
+        let regs = [0.0f32; 128];
+        (0..n).map(|_| eval_voice(v, p, &regs, 48000.0)).collect()
+    }
+
+    #[test]
+    fn compile_ignores_non_operators() {
+        // digits and dots are params/empty, not nodes
+        let p = compile(&grid_from("O5.\n!.."));
+        assert_eq!(p.nodes.len(), 2); // O and !
+    }
+
+    #[test]
+    fn compile_wires_input_from_above() {
+        // O over ! -> the ! node's input is the O's slot
+        let p = compile(&grid_from("O\n!"));
+        let out_node = p.nodes.iter().find(|n| matches!(n.op, Op::Out)).unwrap();
+        assert!(out_node.input.is_some());
+    }
+
+    #[test]
+    fn compile_reads_left_param() {
+        // '5' left of L becomes a constant param
+        let p = compile(&grid_from("5L"));
+        let lp = p.nodes.iter().find(|n| matches!(n.op, Op::Low)).unwrap();
+        assert!(matches!(lp.left, Param::Const(x) if (x - 5.0).abs() < 1e-6));
+    }
+
+    #[test]
+    fn compile_lowercase_left_is_cc_reg() {
+        let p = compile(&grid_from("aG"));
+        let g = p.nodes.iter().find(|n| matches!(n.op, Op::Gain)).unwrap();
+        assert!(matches!(g.left, Param::Reg(0)));
+    }
+
+    #[test]
+    fn compile_detects_envelope() {
+        assert!(compile(&grid_from("O\nE\n!")).has_env);
+        assert!(!compile(&grid_from("O\n!")).has_env);
+    }
+
+    #[test]
+    fn empty_grid_is_silent() {
+        let p = compile(&grid_from("...\n..."));
+        let mut v = voice(440.0, 1.0, 1.0);
+        assert!(render(&mut v, &p, 64).iter().all(|&y| y == 0.0));
+    }
+
+    #[test]
+    fn sine_is_bounded_and_audible() {
+        let p = compile(&grid_from("O\n!"));
+        let mut v = voice(440.0, 1.0, 1.0);
+        let out = render(&mut v, &p, 2048);
+        assert!(out.iter().all(|&y| y.abs() <= 1.0 + 1e-6));
+        assert!(out.iter().cloned().fold(0.0, f32::max) > 0.5); // reaches amplitude
+    }
+
+    #[test]
+    fn saw_first_sample_is_minus_one() {
+        // phase starts at 0 -> saw = 2*0-1 = -1
+        let p = compile(&grid_from("A\n!"));
+        let mut v = voice(440.0, 1.0, 1.0);
+        assert!((render(&mut v, &p, 1)[0] - (-1.0)).abs() < 1e-6);
+    }
+
+    #[test]
+    fn outputs_sum_across_columns() {
+        // two saw->out columns: first sample -1 + -1 = -2
+        let p = compile(&grid_from("A.A\n!.!"));
+        let mut v = voice(440.0, 1.0, 1.0);
+        assert!((render(&mut v, &p, 1)[0] - (-2.0)).abs() < 1e-6);
+    }
+
+    #[test]
+    fn no_envelope_is_gated_by_note() {
+        let p = compile(&grid_from("A\n!"));
+        let mut open = voice(440.0, 1.0, 1.0);
+        let mut shut = voice(440.0, 0.0, 1.0);
+        assert!(render(&mut open, &p, 1)[0].abs() > 0.5);
+        assert_eq!(render(&mut shut, &p, 1)[0], 0.0); // gate 0 -> silent
+    }
+
+    #[test]
+    fn envelope_rises_then_releases() {
+        let p = compile(&grid_from("O\nE\n!"));
+        let mut v = voice(440.0, 1.0, 1.0);
+        render(&mut v, &p, 8000); // ~sustain reached
+        let peak = v.env_level;
+        assert!(peak > 0.9, "env should rise to sustain, got {peak}");
+        v.gate = 0.0;
+        render(&mut v, &p, 24000); // release (~0.5s >> 0.15s release)
+        assert!(v.env_level < 0.1, "env should decay after note off, got {}", v.env_level);
+    }
+
+    #[test]
+    fn mix_adds_left_cell() {
+        // (1,0)=A saw(-1); (1,1)=M reads above(empty=0) + left cell A(-1) = -1
+        let p = compile(&grid_from("A.\nAM\n.!"));
+        let mut v = voice(440.0, 1.0, 1.0);
+        assert!((render(&mut v, &p, 1)[0] - (-1.0)).abs() < 1e-6);
+    }
+
+    #[test]
+    fn cutoff_hz_is_monotonic() {
+        assert!(cutoff_hz(0.0) < cutoff_hz(5.0));
+        assert!(cutoff_hz(5.0) < cutoff_hz(9.0));
+    }
+}

src/engine.rs

@@ -91,3 +91,75 @@ impl Engine {
         (mix * 0.3).tanh()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::dsp::compile;
+    use crate::grid::Grid;
+
+    #[cfg(test)]
+    impl Engine {
+        fn first_freq(&self) -> Option<f32> {
+            self.voices.iter().find(|v| v.active).map(|v| v.freq)
+        }
+        fn reg(&self, i: usize) -> f32 {
+            self.regs[i]
+        }
+    }
+
+    fn grid_from(src: &str) -> Grid {
+        let mut g = Grid::new();
+        for (r, line) in src.lines().enumerate() {
+            for (c, ch) in line.chars().enumerate() {
+                g.set(c, r, ch);
+            }
+        }
+        g
+    }
+
+    #[test]
+    fn noteon_maps_a4_to_440() {
+        let mut e = Engine::new(4, 48000.0);
+        e.apply(Event::NoteOn { note: 69, vel: 100 });
+        assert!((e.first_freq().unwrap() - 440.0).abs() < 0.01);
+        assert_eq!(e.active_voices(), 1);
+    }
+
+    #[test]
+    fn noteoff_reaps_gated_voice() {
+        let p = compile(&grid_from("A\n!")); // no envelope -> gate reaps immediately
+        let mut e = Engine::new(4, 48000.0);
+        e.apply(Event::NoteOn { note: 60, vel: 100 });
+        e.render(&p);
+        assert_eq!(e.active_voices(), 1);
+        e.apply(Event::NoteOff { note: 60 });
+        e.render(&p);
+        assert_eq!(e.active_voices(), 0);
+    }
+
+    #[test]
+    fn monophonic_steals_the_oldest_voice() {
+        let mut e = Engine::new(1, 48000.0);
+        e.apply(Event::NoteOn { note: 60, vel: 100 });
+        e.apply(Event::NoteOn { note: 72, vel: 100 });
+        assert_eq!(e.active_voices(), 1);
+        assert!((e.first_freq().unwrap() - 440.0 * 2f32.powf((72.0 - 69.0) / 12.0)).abs() < 0.01);
+    }
+
+    #[test]
+    fn cc_writes_register() {
+        let mut e = Engine::new(2, 48000.0);
+        e.apply(Event::Cc { idx: 0, val: 127 });
+        assert!((e.reg(0) - 1.0).abs() < 1e-6);
+    }
+
+    #[test]
+    fn master_output_is_limited() {
+        // many stacked saws would exceed 1.0 without the limiter
+        let p = compile(&grid_from("A.A.A.A\n!.!.!.!"));
+        let mut e = Engine::new(4, 48000.0);
+        e.apply(Event::NoteOn { note: 60, vel: 127 });
+        assert!(e.render(&p).abs() <= 1.0);
+    }
+}

src/grid.rs

@@ -1,31 +1,97 @@
-//! The fixed-size character grid that is the editor surface.
+//! The character grid — the editor surface. Logical size (`w`×`h`) is
+//! resizable up to the max; cells are stored at a fixed `MAX_W` stride so a
+//! resize never remaps existing content and compiled slot indices stay stable.
 
-pub const W: usize = 24;
+pub const MAX_W: usize = 40;
-pub const H: usize = 16;
+pub const MAX_H: usize = 24;
-pub const SLOTS: usize = W * H;
+pub const SLOTS: usize = MAX_W * MAX_H;
+pub const DEFAULT_W: usize = 24;
+pub const DEFAULT_H: usize = 16;
+pub const RULER: usize = 8;
 
 #[derive(Clone)]
 pub struct Grid {
+    pub w: usize,
+    pub h: usize,
     cells: Vec<char>,
 }
 
 impl Grid {
     pub fn new() -> Self {
-        Grid { cells: vec!['.'; SLOTS] }
+        Grid { w: DEFAULT_W, h: DEFAULT_H, cells: vec!['.'; SLOTS] }
     }
 
     #[inline]
     pub fn get(&self, col: usize, row: usize) -> char {
-        if col < W && row < H {
+        if col < self.w && row < self.h {
-            self.cells[row * W + col]
+            self.cells[row * MAX_W + col]
         } else {
             '.'
         }
     }
 
     pub fn set(&mut self, col: usize, row: usize, c: char) {
-        if col < W && row < H {
+        if col < self.w && row < self.h {
-            self.cells[row * W + col] = c;
+            self.cells[row * MAX_W + col] = c;
         }
     }
+
+    /// Resize to nh×nw, clamped to [1, MAX]. Content keeps its position.
+    pub fn resize(&mut self, nh: usize, nw: usize) {
+        self.h = nh.clamp(1, MAX_H);
+        self.w = nw.clamp(1, MAX_W);
+    }
+}
+
+/// orca-c's ruler snap: resize by one ruler division, snapped to a
+/// ruler-aligned size (1, 9, 17, ...) rather than a plain +/-1.
+pub fn ruler_snap(size: usize, delta_rulers: isize) -> usize {
+    if size == 0 {
+        return if delta_rulers > 0 { RULER * delta_rulers as usize } else { 1 };
+    }
+    let size = if delta_rulers < 0 { size + RULER - 1 } else { size };
+    let n = ((size as isize - 1) / RULER as isize + delta_rulers).max(0);
+    (RULER as isize * n + 1) as usize
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn ruler_snap_grows_and_shrinks() {
+        // ruler-aligned sizes are 1, 9, 17, ...
+        assert_eq!(ruler_snap(24, 1), 25);
+        assert_eq!(ruler_snap(24, -1), 17);
+        assert_eq!(ruler_snap(1, -1), 1); // cannot go below 1
+    }
+
+    #[test]
+    fn resize_clamps_to_bounds() {
+        let mut g = Grid::new();
+        g.resize(9999, 9999);
+        assert_eq!((g.h, g.w), (MAX_H, MAX_W));
+        g.resize(0, 0);
+        assert_eq!((g.h, g.w), (1, 1));
+    }
+
+    #[test]
+    fn get_out_of_bounds_is_empty() {
+        let g = Grid::new();
+        assert_eq!(g.get(MAX_W + 5, MAX_H + 5), '.');
+        assert_eq!(g.get(g.w, 0), '.'); // just past the right edge
+    }
+
+    #[test]
+    fn set_get_roundtrip_and_resize_preserves() {
+        let mut g = Grid::new();
+        g.set(3, 2, 'O');
+        assert_eq!(g.get(3, 2), 'O');
+        g.resize(4, 4); // shrink below the cell? (3,2) still inside 4x4
+        assert_eq!(g.get(3, 2), 'O');
+        g.resize(2, 2); // now (3,2) is out of bounds -> hidden
+        assert_eq!(g.get(3, 2), '.');
+        g.resize(MAX_H, MAX_W); // grow back -> content returns (fixed stride)
+        assert_eq!(g.get(3, 2), 'O');
+    }
 }

src/tui.rs

@@ -1,7 +1,7 @@
 //! Grid editor. crossterm renderer adapted from orca-rs's grid view: a centered
-//! canvas with per-glyph colour and a change-diff so only cells that actually
+//! canvas with per-glyph colour, ruler marks, resize bindings, and a change-diff
-//! change get repainted (a full clear+redraw each frame flickers over SSH on
+//! so only cells that actually change repaint (a full clear+redraw each frame
-//! terminals that ignore synchronized-update, e.g. macOS Terminal). `?` toggles
+//! flickers over SSH on terminals that ignore synchronized-update). `?` toggles
 //! a detailed help overlay; run a spectrum analyzer on the side if you want one.
 
 use std::io::{self, Write};
@@ -19,7 +19,7 @@ use crossterm::terminal::{
 use crossterm::{execute, queue, terminal};
 
 use crate::dsp::{compile, Program};
-use crate::grid::{Grid, H, W};
+use crate::grid::{ruler_snap, Grid, RULER};
 
 const HELP: &[&str] = &[
     "galdr — grid synthesizer",
@@ -40,6 +40,7 @@ const HELP: &[&str] = &[
     "ROUTING   M mix — adds the cell to its LEFT      ! output to master",
     "",
     "KEYS      arrows move · type a glyph to place · Backspace clears",
+    "          ( ) width -/+   _ + height -/+   Ctrl+arrows resize by one",
     "          ? toggle this help · Esc quit",
 ];
 
@@ -58,7 +59,6 @@ fn glyph_color(c: char) -> Color {
         '!' => Color::Magenta,
         '0'..='9' => Color::Grey,
         'a'..='z' => Color::DarkYellow,
-        '.' => Color::DarkGrey,
         _ => Color::White,
     }
 }
@@ -68,13 +68,24 @@ struct Renderer {
     status: String,
     tw: u16,
     th: u16,
+    gw: usize,
+    gh: usize,
     help: bool,
     init: bool,
 }
 
 impl Renderer {
     fn new() -> Self {
-        Renderer { cells: Vec::new(), status: String::new(), tw: 0, th: 0, help: false, init: false }
+        Renderer {
+            cells: Vec::new(),
+            status: String::new(),
+            tw: 0,
+            th: 0,
+            gw: 0,
+            gh: 0,
+            help: false,
+            init: false,
+        }
     }
 }
 
@@ -102,6 +113,8 @@ pub fn run(
                 continue;
             }
             let ctrl = k.modifiers.contains(KeyModifiers::CONTROL);
+            let mut resized = false;
+            let mut edited = false;
             match k.code {
                 KeyCode::Esc => {
                     if help {
@@ -112,22 +125,60 @@ pub fn run(
                 }
                 KeyCode::Char('c') if ctrl => return Ok(()),
                 KeyCode::Char('?') => help = !help,
-                _ if help => {} // any other key: ignore while help is open
+                _ if help => {}
+                KeyCode::Char('(') => {
+                    grid.resize(grid.h, ruler_snap(grid.w, -1));
+                    resized = true;
+                }
+                KeyCode::Char(')') => {
+                    grid.resize(grid.h, ruler_snap(grid.w, 1));
+                    resized = true;
+                }
+                KeyCode::Char('_') => {
+                    grid.resize(ruler_snap(grid.h, -1), grid.w);
+                    resized = true;
+                }
+                KeyCode::Char('+') => {
+                    grid.resize(ruler_snap(grid.h, 1), grid.w);
+                    resized = true;
+                }
+                KeyCode::Left if ctrl => {
+                    grid.resize(grid.h, grid.w.saturating_sub(1));
+                    resized = true;
+                }
+                KeyCode::Right if ctrl => {
+                    grid.resize(grid.h, grid.w + 1);
+                    resized = true;
+                }
+                KeyCode::Up if ctrl => {
+                    grid.resize(grid.h.saturating_sub(1), grid.w);
+                    resized = true;
+                }
+                KeyCode::Down if ctrl => {
+                    grid.resize(grid.h + 1, grid.w);
+                    resized = true;
+                }
                 KeyCode::Left => cx = cx.saturating_sub(1),
-                KeyCode::Right => cx = (cx + 1).min(W - 1),
+                KeyCode::Right => cx = (cx + 1).min(grid.w - 1),
                 KeyCode::Up => cy = cy.saturating_sub(1),
-                KeyCode::Down => cy = (cy + 1).min(H - 1),
+                KeyCode::Down => cy = (cy + 1).min(grid.h - 1),
                 KeyCode::Backspace | KeyCode::Delete => {
                     grid.set(cx, cy, '.');
-                    prog.store(Arc::new(compile(&grid)));
+                    edited = true;
                 }
                 KeyCode::Char(c) => {
                     grid.set(cx, cy, if c == ' ' { '.' } else { c });
-                    prog.store(Arc::new(compile(&grid)));
+                    edited = true;
-                    cx = (cx + 1).min(W - 1);
                 }
                 _ => {}
             }
+            if resized {
+                cx = cx.min(grid.w - 1);
+                cy = cy.min(grid.h - 1);
+            }
+            if resized || edited {
+                prog.store(Arc::new(compile(&grid)));
+            }
         }
     })();
 
@@ -149,15 +200,20 @@ fn draw(
 ) -> io::Result<()> {
     let (tw, th) = terminal::size()?;
 
-    // Full repaint only on first frame, resize, or a help toggle - never every
+    let full = !r.init
-    // frame (that is the flicker).
+        || tw != r.tw
-    let full = !r.init || tw != r.tw || th != r.th || help != r.help;
+        || th != r.th
+        || help != r.help
+        || grid.w != r.gw
+        || grid.h != r.gh;
     if full {
         queue!(out, Clear(ClearType::All))?;
-        r.cells = vec![('\0', Cs::Fg(Color::Reset)); W * H];
+        r.cells = vec![('\0', Cs::Fg(Color::Reset)); grid.w * grid.h];
         r.status.clear();
         r.tw = tw;
         r.th = th;
+        r.gw = grid.w;
+        r.gh = grid.h;
         r.help = help;
         r.init = true;
     }
@@ -179,27 +235,40 @@ fn draw(
         return out.flush();
     }
 
-    let off_x = (tw as usize).saturating_sub(W) / 2;
+    let off_x = (tw as usize).saturating_sub(grid.w) / 2;
-    let off_y = (th as usize).saturating_sub(H + 1) / 2;
+    let off_y = (th as usize).saturating_sub(grid.h + 1) / 2;
-    for row in 0..H {
+    for row in 0..grid.h {
-        for col in 0..W {
+        for col in 0..grid.w {
-            let c = grid.get(col, row);
+            let raw = grid.get(col, row);
-            let cs = if col == cx && row == cy { Cs::Cursor } else { Cs::Fg(glyph_color(c)) };
+            // ruler mark on empty intersections, for orientation while sizing
-            let idx = row * W + col;
+            let disp = if raw == '.' {
-            if r.cells[idx] == (c, cs) {
+                if row % RULER == 0 && col % RULER == 0 { '+' } else { '.' }
+            } else {
+                raw
+            };
+            let cs = if col == cx && row == cy {
+                Cs::Cursor
+            } else if raw == '.' {
+                Cs::Fg(Color::DarkGrey)
+            } else {
+                Cs::Fg(glyph_color(raw))
+            };
+            let idx = row * grid.w + col;
+            if r.cells[idx] == (disp, cs) {
                 continue;
             }
-            r.cells[idx] = (c, cs);
+            r.cells[idx] = (disp, cs);
             queue!(out, MoveTo((off_x + col) as u16, (off_y + row) as u16), SetAttribute(Attribute::Reset))?;
             match cs {
                 Cs::Cursor => queue!(out, SetAttribute(Attribute::Reverse))?,
                 Cs::Fg(color) => queue!(out, SetForegroundColor(color))?,
             }
-            queue!(out, Print(c))?;
+            queue!(out, Print(disp))?;
         }
     }
 
-    let status = format!("voices {voices}   latency {latency}f   ? help   Esc quit");
+    let status =
+        format!("voices {voices}   {}x{}   latency {latency}f   ? help   Esc quit", grid.w, grid.h);
     if status != r.status {
         r.status = status.clone();
         let pad: String = format!("{status:<width$}", width = tw as usize);