Capabilities reference

When the singleton IAnsiConsole initialises, it builds a IProfile describing the terminal's capabilities. Every render decision - colour downsampling, unicode-vs-ASCII glyph choice, prompt-vs-skip - flows from this profile.

What's detected

Each IProfile carries:

Property	Meaning
ColorSystem	One of TColorSystem.NoColors / Legacy / Standard / EightBit / TrueColor.
Unicode	Boolean — true if the terminal can render wide-character glyphs.
Width / Height	Terminal dimensions in cells (auto-redetected each render).
Interactive	Boolean — true if stdin is a TTY (prompts allowed).
Ansi	Boolean — true if VT escape sequences are supported.

Access via AnsiConsole.Profile:

if AnsiConsole.Profile.Capabilities.Unicode then
  AnsiConsole.WriteLine('Unicode supported')
else
  AnsiConsole.WriteLine('Falling back to ASCII');

Detection rules

The detection logic lives in source/Profile/VSoft.AnsiConsole.Detection.pas.

VT100 / ANSI

Probed by calling SetConsoleMode(ENABLE_VIRTUAL_TERMINAL_PROCESSING) and reading back. We do not use GetVersionEx - on Windows 10/11 it returns Windows 8.2 for unmanifested exes because of the compatibility shim.

Colour system

Picked from a combination of:

• The presence of ENABLE_VIRTUAL_TERMINAL_PROCESSING (gates anything above Legacy).
• Environment variables: COLORTERM (truecolor / 24bit), TERM_PROGRAM, TERM.
• Heuristics for known terminals (Windows Terminal, ConEmu, VS Code).

Override at runtime:

profile := AnsiConsole.Profile;
profile.WithColorSystem(TColorSystem.Standard);   // force 16-colour

Or via TAnsiConsoleSettings:

settings := TAnsiConsoleSettings.Default;
settings.ColorSystem := TColorSystemSupport.TrueColor;
console := AnsiConsole.CreateFromSettings(settings);

Unicode

Detected from the active code page. Force it explicitly via settings if the heuristic gets it wrong (e.g. legacy terminal with a unicode font).

Interactive

stdin.IsTTY from VSoft.System.Console. False inside CI / piped scripts

• prompts then return defaults instead of blocking.

CI enrichers

Profile enrichers override defaults when running under known CI systems. Each enricher checks an env var and tweaks the profile:

CI	Detected via	Effect
GitHub Actions	GITHUB_ACTIONS=true	Disables interactivity, raises colour to TrueColor.
GitLab CI	GITLAB_CI=true	Disables interactivity.
Travis	TRAVIS=true	Disables interactivity.
AppVeyor	APPVEYOR=true	Disables interactivity.
Jenkins	JENKINS_URL set	Disables interactivity.
TeamCity	TEAMCITY_VERSION set	Disables interactivity.
Bitbucket Pipelines	BITBUCKET_BUILD_NUMBER set	Disables interactivity.

The enricher list lives in source/Profile/VSoft.AnsiConsole.Enrichment.pas. You can plug your own IProfileEnricher by extending the registry; in CI this means progress bars don't try to redraw and prompts don't block on a non-existent terminal.

Building a custom profile

For tests / non-interactive flows, build an IAnsiConsole directly with explicit settings:

settings := TAnsiConsoleSettings.Default;
settings.ColorSystem := TColorSystemSupport.NoColors;
settings.Interactive := TInteractionSupport.Off;
console := AnsiConsole.CreateFromSettings(settings);
AnsiConsole.SetConsole(console);

TColorSystemSupport and TInteractionSupport add a Detect value — when set, the corresponding enricher / detector decides at runtime. The library default is Detect for everything.

See also

• Architecture — pipeline overview.
• Colours — how the colour system affects rendering.
• Recorder — captures bypass the profile and retain full RGB; capability handling is on the encoder.