refactor: extract terminal emulator behind a backend trait

Cargo.toml

@@ -29,3 +29,5 @@ serde_json = "1.0.150"
 crossterm = "0.28"
 ttf-parser = { version = "0.25.1", default-features = false, features = ["std"] }
 dialoguer = { version = "0.11", default-features = false }
+compact_str = "0.10.0"
+bitflags = "2.13.1"

SKILL.md

@@ -163,6 +163,7 @@ shell-use mouse drag 2 2 20 2            # drag from (2,2) to (20,2)
 shell-use cells 0 0 10 1                       # inspect char/fg/bg/flags
 shell-use expect text "ERROR" --fg "#ff0000"   # text present AND red
 shell-use expect text "OK" --fg 2 --bg 0       # ansi-256 fg/bg
+shell-use expect text "plain" --fg default     # asserts the cell set no color
 ```
 
 ## Workflow: snapshot testing

bindings/js/src/types.ts

@@ -1,5 +1,14 @@
 export type Color = "default" | number | string;
 
+/** `"none"` is a value, not an absence: an un-underlined cell reports it. */
+export type UnderlineStyle =
+  | "none"
+  | "single"
+  | "double"
+  | "curly"
+  | "dotted"
+  | "dashed";
+
 export type Shell =
   | "bash"
   | "powershell"
@@ -24,13 +33,27 @@ export interface Size {
 export interface Cell {
   x: number;
   y: number;
+  /** The cell's grapheme; `" "` when blank, `""` for the second column of a double-width character. */
   char: string;
   fg: Color;
   bg: Color;
   bold: boolean;
+  dim: boolean;
   italic: boolean;
-  underline: boolean;
   inverse: boolean;
+  invisible: boolean;
+  strike: boolean;
+  /** Always `false` from the alacritty backend, which cannot report blink. */
+  blink: boolean;
+  /** Shorthand for `underline_style !== "none"`. */
+  underline: boolean;
+  underline_style: UnderlineStyle;
+  /**
+   * `"default"` means the underline follows the text color. Tracked
+   * independently of `underline_style`, so a cell that set SGR 58 without an
+   * underline still reports the color it would use.
+   */
+  underline_color: Color;
 }
 
 export interface State {

bindings/python/src/shell_use/types.py

@@ -1,22 +1,37 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
-from typing import Any, Dict, Optional, Union
+from typing import Any, Dict, Literal, Optional, Union
 
 Color = Union[str, int]
+#: ``"none"`` is a value, not an absence: an un-underlined cell reports it.
+UnderlineStyle = Literal["none", "single", "double", "curly", "dotted", "dashed"]
 
 
 @dataclass
 class Cell:
     x: int
     y: int
+    #: The cell's grapheme; ``" "`` when blank, ``""`` for the second column
+    #: of a double-width character.
     char: str
     fg: Color
     bg: Color
     bold: bool
+    dim: bool
     italic: bool
-    underline: bool
     inverse: bool
+    invisible: bool
+    strike: bool
+    #: Always ``False`` from the alacritty backend, which cannot report blink.
+    blink: bool
+    #: Shorthand for ``underline_style != "none"``.
+    underline: bool
+    underline_style: UnderlineStyle
+    #: ``"default"`` means the underline follows the text color. Tracked
+    #: independently of ``underline_style``, so a cell that set SGR 58 without
+    #: an underline still reports the color it would use.
+    underline_color: Color
 
 
 @dataclass