§5 Color System — Monospace Design TUI

§5.1 Semantic Color Roles

Applications MUST define colors for these 5 semantic roles:

Role	Purpose	Example Use
Primary	Brand identity, key actions	Action bar, active tab indicator
Secondary	Supporting UI elements	Panel borders, secondary buttons
Tertiary	Accent, highlight	Links, selected items
Error	Error states, destructive actions	Error messages, delete buttons
Neutral	Backgrounds, body text, borders	Content area, panel backgrounds

Colors MUST be assigned by semantic role, not by literal color name. Applications MUST NOT hardcode ANSI color indices directly in layout code — use a theme or token layer. (M3 §3 color system)

§5.2 Status Colors

Applications MUST use these 4 semantic status colors consistently:

Status	Color	Use
Healthy / Success	Green	Passing checks, active services, confirmations
Error / Critical	Red	Failures, blocked states, destructive confirmations
Warning / Caution	Yellow	Degraded performance, approaching limits
Inactive / Disabled	Dim gray	Placeholder text, disabled controls, secondary info

(tui-architect common violations — status color palette)

§5.3 Color Independence

Color MUST NOT be the sole indicator of any state or meaning. Every use of color MUST be paired with at least one of:

Text label (e.g., “Error:”, “OK”)
Typographic attribute (bold, dim, underline)
Symbol or marker (e.g., ✓, ✗, ⚠, ◉)

This rule is non-negotiable for accessibility. (Apple HIG §4 color independence, monospace-design-tui-research.md cross-cutting synthesis)

§5.4 Dialog Severity Colors

Dialogs MUST use background color to indicate severity:

Severity	Background	Required Non-Color Indicator
Notification / Info	Neutral background	Title or icon (e.g., `ℹ`)
Warning	Yellow-tinted background	`⚠` symbol and/or “Warning:” label
Critical / Error	Red-tinted background	`✗` symbol and/or “Error:” label

Per §5.3, severity background color MUST be paired with a text label or symbol. A dialog with a red background and no textual severity indicator is a violation. (CUA §1 state indicators — pop-up severity colors)

§5.5 Active/Inactive Window Distinction

Active windows MUST render with brighter color attributes than inactive windows. The distinction MUST be visible without relying on color alone — active windows MUST also use double-line borders (§6) and/or bold title text. (CUA §1, OS/2 §2)

§5.6 Color Capability Detection

Applications MUST detect the terminal’s color capability and degrade gracefully:

Truecolor (24-bit) — COLORTERM=truecolor or COLORTERM=24bit
256-color — TERM contains 256color
16-color — Standard ANSI colors
Monochrome — Bold, dim, underline, reverse video only

Applications MUST NOT emit color codes unsupported by the detected capability level. Applications MUST remain fully functional in monochrome mode. (Terminal §6 color detection)