Fix capacity-overflow panic in print_snip at --terminal-width 1

`InteractivePrinter::print_snip` computes the snip separator width as
`term_width - panel_count - snip_left_count - title_count`. At `--terminal-width 1`
the panel is disabled and `title_count == 2`, so the subtraction underflows
`usize` (release has no overflow-checks, so it wraps to ~usize::MAX); `str::repeat`
then aborts with "capacity overflow" whenever a snip separator is emitted (two or
more disjoint line ranges, or a diff gap) — which the default style does.

Use `saturating_sub` for the repeat counts so they clamp to 0 instead of
underflowing. Added an integration test.

CHANGELOG.md

@@ -22,6 +22,7 @@
 - Syntax highlighting for Python files using uv as script runner in shebang #3689 (@janlarres)
 
 ## Bugfixes
+- Fix `capacity overflow` panic when printing a snip separator at `--terminal-width=1` with multiple line ranges. Closes #3803, see #3804 (@leeewee)
 - Pass `--no-paging` to `bat` invocations inside the bash / zsh / fish / PowerShell shell completion scripts so that shell-level pager wiring (e.g. `LESSOPEN='|-bat -f -pp %s'`) cannot inject ANSI escape sequences into the completion candidates. Closes #3760 (@mvanhorn)
 - Quote filenames before substituting them into `$LESSOPEN` / `$LESSCLOSE` templates, preventing shell injection when a filename contains shell metacharacters, see #3726 (@curious-rabbit)
 - Fix `--list-themes` unconditionally probing the terminal via OSC 10/11 even when `--theme` was set to an explicit value, see #3700 (regression introduced in bc42149a). (@optimistiCli)

src/printer.rs

@@ -603,11 +603,23 @@ impl Printer for InteractivePrinter<'_> {
         let title = "8<";
         let title_count = title.chars().count();
 
-        let snip_left = "─ ".repeat((self.config.term_width - panel_count - (title_count / 2)) / 4);
+        let snip_left = "─ ".repeat(
+            self.config
+                .term_width
+                .saturating_sub(panel_count)
+                .saturating_sub(title_count / 2)
+                / 4,
+        );
         let snip_left_count = snip_left.chars().count(); // Can't use .len() with Unicode.
 
-        let snip_right =
-            " ─".repeat((self.config.term_width - panel_count - snip_left_count - title_count) / 2);
+        let snip_right = " ─".repeat(
+            self.config
+                .term_width
+                .saturating_sub(panel_count)
+                .saturating_sub(snip_left_count)
+                .saturating_sub(title_count)
+                / 2,
+        );
 
         writeln!(
             handle,

tests/integration_tests.rs

@@ -305,6 +305,19 @@ fn line_range_multiple() {
         .stdout("line 1\nline 2\nline 4\n");
 }
 
+#[test]
+fn snip_at_terminal_width_one_does_not_panic() {
+    bat()
+        .arg("multiline.txt")
+        .arg("--style=snip")
+        .arg("--color=always")
+        .arg("--terminal-width=1")
+        .arg("--line-range=1:2")
+        .arg("--line-range=4:4")
+        .assert()
+        .success();
+}
+
 #[test]
 fn line_range_multiple_with_context() {
     bat()