chore(deps): bump vt100 to 0.18 and migrate the NonZero screen API

Cargo.toml

@@ -73,7 +73,7 @@ fancy-regex = "0.19"
 chrono = { version = "0.4", default-features = false, features = ["std", "clock"] }
 chrono-tz = "0.10"
 # In-process terminal screen model (terminal feature)
-vt100 = "0.16"
+vt100 = "0.18"
 
 # Compression
 flate2 = "1"

crates/bashkit/src/terminal/mod.rs

@@ -339,7 +339,9 @@ impl Terminal {
     pub fn screen_rows(&self) -> Vec<String> {
         self.tty.with_screen(|s| {
             let (_, cols) = s.size();
-            s.rows(0, cols).map(|r| r.trim_end().to_string()).collect()
+            s.rows(0, cols.get())
+                .map(|r| r.trim_end().to_string())
+                .collect()
         })
     }
 
@@ -396,7 +398,10 @@ impl Terminal {
         Some(self.tty.with_screen(|s| {
             let (row, col) = s.cursor_position();
             let (_, cols) = s.size();
-            let text = s.rows(0, cols).nth(usize::from(row)).unwrap_or_default();
+            let text = s
+                .rows(0, cols.get())
+                .nth(usize::from(row))
+                .unwrap_or_default();
             text.chars().take(usize::from(col)).collect::<String>()
         }))
     }

crates/bashkit/src/terminal/tty.rs

@@ -6,6 +6,7 @@
 //! holds the lock across an `.await`.
 
 use std::collections::VecDeque;
+use std::num::NonZero;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex, MutexGuard, PoisonError};
 
@@ -25,6 +26,15 @@ pub(crate) const MAX_OUTPUT_TAP: usize = 256 * 1024;
 /// Lines of primary-screen history kept for `history_text`.
 pub(crate) const SCROLLBACK_LINES: usize = 1000;
 
+/// vt100 0.18 takes screen dimensions as `NonZero<u16>`; [`TerminalSize`] keeps
+/// plain `u16` because its fields are public API. `TerminalSize::new` already
+/// clamps to 2, but the struct can also be built literally, so a zero can still
+/// reach here. Clamp it to 1 rather than panic: a degenerate size is the
+/// caller's to notice, and it is not worth aborting a session over.
+fn nz(v: u16) -> NonZero<u16> {
+    NonZero::new(v).unwrap_or(NonZero::<u16>::MIN)
+}
+
 /// What a blocking terminal read returned.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub(crate) enum TtyEvent {
@@ -85,7 +95,7 @@ impl Tty {
                 reading_line: false,
                 resized: false,
                 closed: false,
-                screen: vt100::Parser::new(size.rows, size.cols, SCROLLBACK_LINES),
+                screen: vt100::Parser::new(nz(size.rows), nz(size.cols), SCROLLBACK_LINES),
                 output: Vec::new(),
                 tap: Vec::new(),
                 tap_total: 0,
@@ -136,7 +146,9 @@ impl Tty {
     pub(crate) fn resize(&self, size: TerminalSize) {
         {
             let mut st = self.lock();
-            st.screen.screen_mut().set_size(size.rows, size.cols);
+            st.screen
+                .screen_mut()
+                .set_size(nz(size.rows), nz(size.cols));
             st.resized = true;
             st.waiting = false;
         }
@@ -190,6 +202,7 @@ impl Tty {
         let mut st = self.lock();
         let screen = st.screen.screen_mut();
         let (rows, cols) = screen.size();
+        let (rows, cols) = (rows.get(), cols.get());
         let rows = usize::from(rows);
         screen.set_scrollback(usize::MAX);
         let total = screen.scrollback();
@@ -212,7 +225,10 @@ impl Tty {
 
     pub(crate) fn size(&self) -> TerminalSize {
         let (rows, cols) = self.lock().screen.screen().size();
-        TerminalSize { rows, cols }
+        TerminalSize {
+            rows: rows.get(),
+            cols: cols.get(),
+        }
     }
 
     pub(crate) fn set_raw(&self, raw: bool) {

knowledge/integrations/in-process-terminal.md

@@ -61,6 +61,13 @@ C FFI, which would break the wasm, PyPI and npm builds, for a feature whose
 screen needs are basic (cells, cursor, alternate screen). Revisit only if
 fidelity gaps show up that vt100 cannot close.
 
+From vt100 0.18 the screen dimensions are `NonZero<u16>`. `TerminalSize` keeps
+plain `u16`, because its fields are public API, and converts at the vt100
+boundary only. `TerminalSize::new` clamps to 2, but the struct can also be
+built literally, so a zero can still reach that boundary; it clamps to 1 rather
+than panicking, since a degenerate size is the caller's to notice and not worth
+aborting a session over.
+
 ## Decision: device handle via execution extensions
 
 The shell loop passes the `Tty` handle on every `exec_with_options` call

supply-chain/config.toml

@@ -2114,9 +2114,9 @@ version = "0.9.5"
 criteria = "safe-to-deploy"
 
 [[exemptions.vt100]]
-version = "0.16.2"
+version = "0.18.1"
 criteria = "safe-to-deploy"
-notes = "Terminal screen model for the optional `terminal` feature. Pure parsing/state; reviewed: no unsafe, no host I/O, process, or network access."
+notes = "Terminal screen model for the optional `terminal` feature. Pure parsing/state. The exemption moves from 0.16.2 rather than gaining a delta audit: that delta is ~3100 lines across a dozen files plus a new capture.rs, so a delta audit would claim a review that diff does not get. Checked instead for what the exemption asserts, and all of it still holds: zero `unsafe` in src (unchanged from 0.16.2), zero use of std::fs, std::net, std::process or std::env, and no new runtime dependency -- 0.18.1 adds only an optional `embedded-io`, which stays unenabled and is absent from vt100's resolved deps in Cargo.lock (itoa, unicode-width, vte); vte stays at 0.15.0."
 
 [[exemptions.vte]]
 version = "0.15.0"