Module irc 

Available on crate feature output-irc only.

mIRC ^C color-code export backend (E012 US2 — FR-006, FR-015, FR-027).

Format

mIRC encodes colors as a ^C (0x03) prefix followed by 1-2 decimal digits selecting the foreground palette index from the 16-color standard table (0..=15). Optionally a ,BB suffix selects the background. Reset is ^O (0x0F).

Non-printable stripping (FR-015)

ASCII C0 control bytes (0x00..=0x1F except 0x09 tab) and the C1 range (0x7F..=0x9F) are stripped from cell text per FR-015. UTF-8 multibyte continuation bytes (0x80..=0xBF) are PRESERVED when they’re part of a valid UTF-8 sequence — we operate on &str, not &[u8], so the standard library has already validated UTF-8 boundaries before we see the input. The C1 range only intersects the continuation range, but bytes that appear as the start of a multi-byte sequence won’t be in 0x80..=0x9F (UTF-8 leaders are 0xC2..=0xF4).

In practical terms: iterating .chars() gives us validated codepoints, and we strip the BMP code-point if (c as u32) < 0x20 && c != '\t' OR c == '\x7F' OR (c as u32 >= 0x80 && c as u32 <= 0x9F).

Pre-sized writer (FR-027)

Single-pass: we iterate cells once and emit both color codes and text bytes in the same loop. Vec<u8>::with_capacity(w * h * 6) covers ^C99,99X (the longest per-cell encoding).

Warn-on-strip

The CLI flag --warn-irc-strip is wired in Phase 9 (T060). This module accepts a boolean warn_on_strip parameter; when true the function emits a single deduplicated stderr warning if any byte was stripped during this call.

Functions

write_irc

Encode grid as a sequence of mIRC ^C color-coded bytes per FR-006 + FR-015 + FR-027.