babysit 0.7.0

Wrap a shell command in a PTY and expose it to external AI agents (Claude / Codex) via subcommands
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204

//! Rendering a `vt100` virtual-terminal screen into the serializable shapes
//! `babysit screenshot` emits (plain text, ANSI, or structured JSON).
//!
//! This is the read-only half of the screen pipeline: `pane` feeds output
//! bytes into the parser, and these functions turn the resulting grid into
//! something an agent can read. Kept separate from `pane` so the PTY/process
//! lifecycle and the rendering logic stay independent.

use crate::cli::ShotFormat;

/// Fallback size used when rendering a screenshot for a session whose worker
/// is no longer running (we replay the on-disk log through a fresh parser and
/// have no record of the final PTY dimensions).
pub const DEFAULT_SCREENSHOT_SIZE: (u16, u16) = (24, 80);

/// Render a finished session's screen by replaying its raw output log through
/// a fresh virtual terminal. Imperfect (the final PTY size is unknown, so we
/// assume a default), but lets `screenshot` work after the command exits.
pub fn render_log(bytes: &[u8], format: ShotFormat, trim: bool) -> serde_json::Value {
    let (rows, cols) = DEFAULT_SCREENSHOT_SIZE;
    let mut parser = vt100::Parser::new(rows, cols, 0);
    parser.process(bytes);
    render_screen(parser.screen(), format, trim)
}

/// Serialize a vt100 color to a compact, agent-friendly string:
/// `"default"`, `"idxN"` (palette index), or `"#rrggbb"` (true color).
fn color_str(c: vt100::Color) -> String {
    match c {
        vt100::Color::Default => "default".to_string(),
        vt100::Color::Idx(i) => format!("idx{i}"),
        vt100::Color::Rgb(r, g, b) => format!("#{r:02x}{g:02x}{b:02x}"),
    }
}

/// Index of the last row with any visible content (for trimming trailing
/// blank lines). Returns 0 when the whole screen is blank.
fn last_nonblank(lines: &[String]) -> usize {
    lines
        .iter()
        .rposition(|l| !l.trim().is_empty())
        .map_or(0, |i| i + 1)
}

/// Render the visible grid of `screen` in the requested format. All variants
/// carry `rows`, `cols`, and `cursor` so an agent knows the geometry and
/// where focus currently is.
pub fn render_screen(screen: &vt100::Screen, format: ShotFormat, trim: bool) -> serde_json::Value {
    let (rows, cols) = screen.size();
    let (cur_row, cur_col) = screen.cursor_position();
    let meta = serde_json::json!({
        "rows": rows,
        "cols": cols,
        "cursor": { "row": cur_row, "col": cur_col, "hidden": screen.hide_cursor() },
        "alternate_screen": screen.alternate_screen(),
    });

    match format {
        ShotFormat::Plain => {
            let mut lines: Vec<String> = screen.rows(0, cols).collect();
            if trim {
                lines.truncate(last_nonblank(&lines));
            }
            let mut out = meta;
            out["format"] = "plain".into();
            out["text"] = lines.join("\n").into();
            out
        }
        ShotFormat::Ansi => {
            let formatted: Vec<Vec<u8>> = screen.rows_formatted(0, cols).collect();
            let mut lines: Vec<String> = formatted
                .iter()
                .map(|b| String::from_utf8_lossy(b).into_owned())
                .collect();
            if trim {
                // Decide what to keep from the plain rows (escape codes make a
                // formatted row never look "blank").
                let plain: Vec<String> = screen.rows(0, cols).collect();
                lines.truncate(last_nonblank(&plain));
            }
            // Each formatted row carries its own SGR state but no cursor
            // movement, so a plain newline joins them cleanly; reset at the end
            // so the caller's terminal isn't left in a stray attribute.
            let text = format!("{}\x1b[0m", lines.join("\n"));
            let mut out = meta;
            out["format"] = "ansi".into();
            out["text"] = text.into();
            out
        }
        ShotFormat::Json => {
            // Only emit cells that carry content or non-default styling, so the
            // payload stays small for an agent to read.
            let mut cells = Vec::new();
            for r in 0..rows {
                for c in 0..cols {
                    let Some(cell) = screen.cell(r, c) else {
                        continue;
                    };
                    if cell.is_wide_continuation() {
                        continue;
                    }
                    let styled = cell.bold()
                        || cell.italic()
                        || cell.underline()
                        || cell.inverse()
                        || !matches!(cell.fgcolor(), vt100::Color::Default)
                        || !matches!(cell.bgcolor(), vt100::Color::Default);
                    if !cell.has_contents() && !styled {
                        continue;
                    }
                    let mut obj = serde_json::Map::new();
                    obj.insert("row".into(), r.into());
                    obj.insert("col".into(), c.into());
                    obj.insert("char".into(), cell.contents().into());
                    if !matches!(cell.fgcolor(), vt100::Color::Default) {
                        obj.insert("fg".into(), color_str(cell.fgcolor()).into());
                    }
                    if !matches!(cell.bgcolor(), vt100::Color::Default) {
                        obj.insert("bg".into(), color_str(cell.bgcolor()).into());
                    }
                    for (k, v) in [
                        ("bold", cell.bold()),
                        ("italic", cell.italic()),
                        ("underline", cell.underline()),
                        ("inverse", cell.inverse()),
                    ] {
                        if v {
                            obj.insert(k.into(), true.into());
                        }
                    }
                    cells.push(serde_json::Value::Object(obj));
                }
            }
            let mut out = meta;
            out["format"] = "json".into();
            out["cells"] = cells.into();
            out
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Build a screen by feeding `bytes` into a fresh parser.
    fn screen_of(bytes: &[u8]) -> vt100::Parser {
        let mut p = vt100::Parser::new(24, 80, 0);
        p.process(bytes);
        p
    }

    #[test]
    fn plain_reflects_in_place_redraw_not_the_raw_stream() {
        // Print 3 lines, move up 2 and overwrite the middle one. The raw
        // stream has 4 lines; the *screen* has 3. (CRLF models the bytes a PTY
        // actually logs, after the line discipline's \nā†’\r\n translation.)
        let p = screen_of(b"A\r\nB\r\nC\r\n\x1b[2A\x1b[2KB2\r\n");
        let out = render_screen(p.screen(), ShotFormat::Plain, true);
        assert_eq!(out["text"], "A\nB2\nC");
        assert_eq!(out["format"], "plain");
    }

    #[test]
    fn trim_drops_trailing_blank_lines() {
        let p = screen_of(b"hi\r\n");
        let trimmed = render_screen(p.screen(), ShotFormat::Plain, true);
        assert_eq!(trimmed["text"], "hi");
        // Untrimmed keeps the full grid height (24 rows = 23 separators).
        let full = render_screen(p.screen(), ShotFormat::Plain, false);
        let text = full["text"].as_str().unwrap();
        assert!(text.starts_with("hi\n"));
        assert_eq!(text.matches('\n').count(), 23);
    }

    #[test]
    fn json_records_inverse_and_color_for_a_selected_row() {
        // An inverse-video red 'X' ā€” the shape a TUI uses to mark a selection.
        let p = screen_of(b"\x1b[31;7mX\x1b[0m");
        let out = render_screen(p.screen(), ShotFormat::Json, true);
        let cells = out["cells"].as_array().unwrap();
        let cell = &cells[0];
        assert_eq!(cell["char"], "X");
        assert_eq!(cell["fg"], "idx1");
        assert_eq!(cell["inverse"], true);
        // Default-styled blank cells are omitted to keep the payload small.
        assert_eq!(cells.len(), 1);
    }

    #[test]
    fn ansi_preserves_escapes_and_resets_at_end() {
        let p = screen_of(b"\x1b[31mred\x1b[0m");
        let out = render_screen(p.screen(), ShotFormat::Ansi, true);
        let text = out["text"].as_str().unwrap();
        assert!(text.contains('\x1b'), "escapes should be preserved");
        assert!(text.ends_with("\x1b[0m"), "should reset SGR at the end");
    }

    #[test]
    fn render_log_replays_a_finished_session() {
        let out = render_log(b"done\n", ShotFormat::Plain, true);
        assert_eq!(out["text"], "done");
    }
}