Skip to content

nbs-ts-render.md

Latest commit

 

History

History
75 lines (51 loc) · 3.14 KB

nbs-ts-render.md

File metadata and controls

75 lines (51 loc) · 3.14 KB

nbs-ts-render

Virtual terminal renderer. Reads raw PTY output from stdin, processes it through a full terminal emulator, and outputs the final screen state as plain UTF-8 text.

Usage

cat ~/.nbs-ts/sessions/<handle>/output.log | nbs-ts-render
nbs-chat export .nbs/chat/poem.chat | nbs-ts-render
nbs-ts-render --width=120 --height=40 < output.log

What It Does

Terminal sessions produce raw output containing ANSI escape sequences — cursor movement, colours, scrolling, erase commands. This is what output.log contains. nbs-ts-render processes all of it through a headless terminal emulator and outputs what a human would see on screen.

All decoration (colour, bold, italic, underline) is stripped. The output is plain text.

Options

Option Default Description
--width=N 80 Screen width in columns
--height=N 24 Screen height in rows
--no-strip off Preserve SGR colour/style escape sequences in output

The defaults match the PTY size used by nbs-ts-helper.

Supported Escape Sequences

  • Cursor: CUP, CUU, CUD, CUF, CUB, CNL, CPL, CHA, VPA, HVP
  • Erase: ED, EL, ECH
  • Scroll: SU, SD, DECSTBM (scroll regions)
  • Insert/Delete: IL, DL, ICH, DCH
  • Tabs: HT, HTS, TBC
  • Cursor save: DECSC (ESC 7), DECRC (ESC 8)
  • Line control: LF, CR, BS, IND, NEL, RI
  • Reset: RIS (ESC c)
  • UTF-8: Full multi-byte character support
  • Wide characters: CJK and emoji (wcwidth-aware)
  • Bidi: UAX #9 RTL support with bracket mirroring

SGR (colour/style), OSC, and DCS sequences are silently consumed.

Terminology: VT100 vs ANSI vs xterm

The DEC VT100 (1978) defined the original escape sequences for cursor movement, erase, and styling. ANSI (ECMA-48/ISO 6429) standardised and extended them. Modern terminal emulators (xterm, iTerm, GNOME Terminal) implement a superset of both, adding UTF-8, 256-colour, true-colour, bracketed paste, and more.

nbs-ts-render implements the subset that Claude Code actually produces: ANSI/ECMA-48 CSI sequences for cursor and erase, DEC private extensions (DECSTBM scroll regions, DECSC/DECRC cursor save), and full UTF-8 including wide characters and RTL text. It does not implement mouse tracking, bracketed paste, or other interactive features — it is a renderer, not an interactive terminal.

Calling it a "VT100 renderer" is a convenient shorthand. More precisely, it is an xterm-subset renderer covering the escape sequences found in real Claude Code session output.

Newline Mode

Bare \n (LF without preceding CR) resets the cursor to column 0 before moving down. This matches terminal newline mode (LNM) and ensures Unix text (which uses bare \n) renders correctly without staircase-stepping across the screen.

Common Uses

# See what an agent's terminal looks like right now
cat ~/.nbs-ts/sessions/$(nbs-ts find nbs-supervisor-poem)/output.log | nbs-ts-render

# Render a chat export as plain text
nbs-chat export .nbs/chat/poem.chat | nbs-ts-render

# Render with a wider terminal
cat output.log | nbs-ts-render --width=160 --height=50

Build

cd src/nbs-ts-render
make && make install