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Lumen Protocol v0, revision 25 (frozen snapshot). © Moonbase 2090 LLC. Licensed under CC-BY-4.0. Report security issues privately via GitHub private vulnerability reporting or [email protected].

Text runs and styling

Runs

A run is UTF-8 text plus a style: family role (body, mono or heading), weight, italic, size step, colour token, underline, strike and link reference.

Colour

Colour tokens are semantic (fg, muted, accent, error), and the theme maps them to colours. Raw RGB is allowed only as a capability.

Cell spans

A run of N cells can hold a shaped proportional string fitted to that width, for use inside grids. Cell spans MUST be created only by authenticated frames, never by grid output. Unverified output cannot create them.

Shaping

Shaping is HarfBuzz-style, with ligatures, emoji and bidi. Applications never measure text.

Copy semantics

Copy is defined as the logical code-point sequence of visible runs, not the shaped glyphs. When shaped glyphs differ from code points, the code points are copied.

Bidi and invisible characters

In command and code blocks, and in pasted command text, the terminal MUST strip the following and show how many were stripped:

  • Bidi override, isolate and mark controls: U+202A–U+202E, U+2066–U+2069, U+200E, U+200F and U+061C.
  • In command text only: zero-width and invisible characters U+200B–U+200D, U+2060–U+2064 and U+FEFF, and tag characters U+E0000–U+E007F.

Elsewhere these characters are rendered visibly as escapes. Command input is displayed in logical order, with bidi reordering disabled, so the command that is displayed is the one that runs.

Visibility

A run is visible only if all of the following hold:

  • Its resolved size is at least 6 px.
  • Its foreground/background contrast ratio is at least 3:1 (WCAG relative luminance).
  • It is not clipped or scrolled out of its block.
  • Its section is expanded.
  • No part of it is covered by any later paint, opaque or not: another run, a cell span, an image or a block. If coverage cannot be computed, the run is treated as covered (fail closed).

A run that fails any test is treated as hidden for copy, search and approvals, and is counted in the hidden-content indicator. Hidden runs never reach copy.