From e2b746dd64b1fd41351f0e1de11c276865e80c91 Mon Sep 17 00:00:00 2001
From: Vassiliy Yegorov <va@egorovanet.ru>
Date: Tue, 9 Jun 2026 20:10:49 +0700
Subject: [PATCH] feat(core): GridSurface feeding PTY bytes into alacritty term

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---
 crates/spacesh-core/src/grid.rs | 83 +++++++++++++++++++++++++++++++++
 crates/spacesh-core/src/lib.rs  |  7 ++-
 2 files changed, 89 insertions(+), 1 deletion(-)
 create mode 100644 crates/spacesh-core/src/grid.rs

diff --git a/crates/spacesh-core/src/grid.rs b/crates/spacesh-core/src/grid.rs
new file mode 100644
index 0000000..1f5e361
--- /dev/null
+++ b/crates/spacesh-core/src/grid.rs
@@ -0,0 +1,83 @@
+use alacritty_terminal::event::VoidListener;
+use alacritty_terminal::grid::Dimensions;
+use alacritty_terminal::index::{Column, Line, Point};
+use alacritty_terminal::term::{Config, Term};
+use alacritty_terminal::vte::ansi::Processor;
+
+/// Fixed-size terminal dimensions for the daemon-side grid.
+#[derive(Clone, Copy)]
+pub struct GridSize {
+    pub cols: usize,
+    pub lines: usize,
+}
+
+impl Dimensions for GridSize {
+    fn total_lines(&self) -> usize {
+        self.lines
+    }
+    fn screen_lines(&self) -> usize {
+        self.lines
+    }
+    fn columns(&self) -> usize {
+        self.cols
+    }
+}
+
+/// Owns an alacritty terminal model and feeds raw PTY bytes into it.
+pub struct GridSurface {
+    term: Term<VoidListener>,
+    parser: Processor,
+    size: GridSize,
+}
+
+impl GridSurface {
+    pub fn new(cols: u16, rows: u16) -> Self {
+        let size = GridSize { cols: cols as usize, lines: rows as usize };
+        let term = Term::new(Config::default(), &size, VoidListener);
+        Self { term, parser: Processor::new(), size }
+    }
+
+    pub fn feed(&mut self, bytes: &[u8]) {
+        self.parser.advance(&mut self.term, bytes);
+    }
+
+    pub fn resize(&mut self, cols: u16, rows: u16) {
+        self.size = GridSize { cols: cols as usize, lines: rows as usize };
+        self.term.resize(self.size);
+    }
+
+    pub fn size(&self) -> GridSize {
+        self.size
+    }
+
+    /// Read the visible character at (line, col) — used by tests and the snapshot writer.
+    pub fn char_at(&self, line: usize, col: usize) -> char {
+        let point = Point::new(Line(line as i32), Column(col));
+        self.term.grid()[point].c
+    }
+
+    pub fn term(&self) -> &Term<VoidListener> {
+        &self.term
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn feeding_plain_text_lands_in_the_grid() {
+        let mut g = GridSurface::new(20, 5);
+        g.feed(b"hello");
+        assert_eq!(g.char_at(0, 0), 'h');
+        assert_eq!(g.char_at(0, 4), 'o');
+    }
+
+    #[test]
+    fn carriage_return_and_newline_move_the_cursor() {
+        let mut g = GridSurface::new(20, 5);
+        g.feed(b"ab\r\ncd");
+        assert_eq!(g.char_at(0, 0), 'a');
+        assert_eq!(g.char_at(1, 0), 'c');
+    }
+}
diff --git a/crates/spacesh-core/src/lib.rs b/crates/spacesh-core/src/lib.rs
index 1b486d8..50db45b 100644
--- a/crates/spacesh-core/src/lib.rs
+++ b/crates/spacesh-core/src/lib.rs
@@ -1 +1,6 @@
-// modules added in Tasks 11-12
+pub mod grid;
+// snapshot module added in Task 12
+// pub mod snapshot;
+
+pub use grid::GridSurface;
+// pub use snapshot::Snapshot;