term-chameleon 0.2.2

Adaptive contrast/readability toolkit for translucent terminals, starting with iTerm2.

Term Chameleon

Keep terminal text readable on translucent ("glass") terminals, automatically.

Glassy terminal themes look great until white text disappears over a bright browser window behind them, dim text vanishes over a dark blur, or iTerm2's Light/Dark profile variants silently override your palette. Term Chameleon diagnoses and fixes those readability failures, and can watch your screen and adapt your terminal's colors and transparency live as the background behind it changes. macOS + iTerm2 today; OSC color sequences work on Kitty, Ghostty, and Alacritty too.

Quickstart

pip install 'term-chameleon[iterm]'
term-chameleon setup --yes

setup --yes runs a permission-free self-check and installs the adaptive "Glass" profile into iTerm2. Select that profile in iTerm2 and you have a tuned, readable glass terminal.

Want it to adapt automatically as your background changes? Install the watcher:

term-chameleon install-watch-daemon

Restart iTerm2. A single background watch-live process now samples your screen and adjusts the terminal's colors and transparency to stay readable. Inspect it with watch-daemon-status; remove it with uninstall-watch-daemon.

That is the whole path: two commands to a tuned profile, three for live auto-adaptation. Everything below is for diagnosing, customizing, or scripting.

What it does

• Diagnose a profile: term-chameleon doctor <profile>.json reports readability failures (low ANSI-black contrast, Light/Dark variant drift, transparency vs contrast) with WCAG ratios and concrete suggestions.
• Fix conservatively: term-chameleon fix <profile>.json previews and applies a readable palette, with a backup and explainable changes.
• Apply a mode to the current terminal over OSC: term-chameleon osc apply dark-glass --write (presets: balanced, dark-glass, bright-safe, accessibility, high-variance-safe, presentation). Works on iTerm2, Kitty, Ghostty, and Alacritty.
• Adapt live: watch-live samples the screen, classifies background-brightness risk with hysteresis, and applies the matching preset to the current iTerm2 session — reducing transparency when a bright background would wash out text, restoring it when the background is dark.

How live adaptation works

watch-live samples the screen (or the iTerm window region) on an interval, estimates background luminance, and runs a risk classifier: bright backgrounds raise washout risk, dark backgrounds lower it. A hysteresis selector with a stable-sample count and a cooldown decides when to switch modes, avoiding thrash on transient changes. On a switch it applies the preset to the live iTerm2 session-local profile — adjusting foreground colors and window transparency together — through the iTerm2 Python API.

See it work

Quickest look — cycle the presets on your current terminal and watch the colors change:

term-chameleon demo

demo applies each preset to your live iTerm2 session in turn, pausing between each, so you can watch the foreground colors and transparency shift. Run it from a visible iTerm2 window.

See the automatic adaptation — the terminal recoloring on its own, no typing — by driving the real watch loop off a repeating bright/dark cycle:

term-chameleon watch-live --yes --demo-cycle --interval 2 --duration 30

The terminal switches modes by itself on a timer — this is the same sample → decide → apply loop the installed daemon runs, only the daemon samples your real screen. To make the switch obvious on an ordinary opaque window, --demo-cycle applies an exaggerated background per mode (dark for dark backgrounds, near-white for bright ones); the real presets keep a subtle dark background and adapt mainly through transparency, which only shows over a translucent window. Record the iTerm2 window with Cmd-Shift-5 while it runs to capture the clip.

To see the full glass effect — colors adapting to a background behind a translucent terminal:

1. In iTerm2, select the installed "Adaptive Glass" profile (translucent), or set your current profile's Transparency to about 30% with Blur on.

2. Put a browser or document window behind the terminal so it shows through.

3. Start the watcher and change what's behind the terminal:

   term-chameleon watch-live --yes --whole-screen --interval 2 --duration 120
   

   Switch the background between a bright white page and a dark one. The terminal's text and transparency adjust to stay readable, and each decision prints as it happens.

To capture a shareable clip, record that session with QuickTime (or Cmd-Shift-5). macOS only lets a screen recording capture the visible space, so recording is the reliable way to produce a demo image or GIF — the demo command intentionally does not screenshot for you (it would capture whatever else is on screen).

Requirements

• macOS with iTerm2 (for live adaptation and profile install)
• Python 3.11+
• The iterm2 Python package for live features: pip install 'term-chameleon[iterm]'

OSC color application (osc apply) needs none of the above and works on any supporting terminal.

CLI examples

Run a permission-free deterministic self-check after installation or inspect local readiness:

term-chameleon check --output-dir artifacts/check
term-chameleon release-check --output-dir artifacts/release-check
term-chameleon setup
term-chameleon setup --yes
term-chameleon setup --live
term-chameleon config-example --output ~/.config/term-chameleon/config.toml
term-chameleon config-check --config ~/.config/term-chameleon/config.toml
term-chameleon watch-live --config ~/.config/term-chameleon/config.toml --dry-run
term-chameleon status
term-chameleon status --live
term-chameleon status --json

setup is a guided flow: it runs deterministic checks and reports status. On first run, bare setup exits nonzero until a healthy profile exists; use setup --yes to install the generated profile, and setup --live to include live iTerm2 API/window readiness.

release-check is the top-level local gate. By default it is permission-free and writes JSON/Markdown reports; add --config, --live, --daemon, or --live-stage to include config validation, live iTerm2 probes, AutoLaunch health, or controlled Safari+iTerm2 screenshot QA.

config-example prints a commented TOML file. config-check validates value types, preset names, region shape, and unknown sections/keys. watch-live, install-watch-daemon, and setup accept --config; explicit CLI flags override config values.

Install a balanced preset into a target directory:

term-chameleon install --target-dir /tmp/iterm-dynamic-profiles --name "Adaptive Glass"

Install an iTerm2 AutoLaunch script that starts the live watcher whenever iTerm2 launches:

term-chameleon install-watch-daemon --dry-run
term-chameleon watch-daemon-status
term-chameleon install-watch-daemon
term-chameleon watch-daemon-status --json
term-chameleon uninstall-watch-daemon --dry-run
term-chameleon uninstall-watch-daemon

uninstall-watch-daemon removes the iTerm2 AutoLaunch script only; it does not stop an already-running watcher process or remove logs/pid files. It creates a backup by default unless --no-backup is passed.

Apply a manual readability mode to a profile JSON file:

term-chameleon mode bright-safe ~/Library/Application\ Support/iTerm2/DynamicProfiles/adaptive-glass.json --dry-run

Check iTerm2 Python API readiness and generate a conservative session-local adapter script:

term-chameleon iterm-api-check
term-chameleon iterm-connect-probe
term-chameleon iterm-window-bounds
term-chameleon iterm-live-script --preset balanced --output /tmp/term-chameleon-live.py

Probe macOS screenshot availability and generate controlled screenshot-test artifacts:

term-chameleon screenshot-probe
term-chameleon screenshot-probe --capture --output artifacts/screenshot-probe/screen.png
term-chameleon screenshot-contrast artifacts/screenshot-probe/screen.png --output-dir artifacts/screenshot-contrast
term-chameleon screenshot-text-contrast artifacts/screenshot-probe/screen.png --output-dir artifacts/screenshot-text-contrast
term-chameleon screenshot-test --output-dir artifacts/screenshot-test
term-chameleon screenshot-test --capture --output-dir artifacts/screenshot-test
term-chameleon background-html --output-dir artifacts/background-html
term-chameleon pattern-script --output-dir artifacts/pattern-script
term-chameleon e2e-stage tests/fixtures/iterm/good-dark-glass.json --output-dir artifacts/e2e-stage
term-chameleon live-stage --dry-run --output-dir artifacts/live-stage
term-chameleon live-stage --yes --capture --output-dir artifacts/live-stage

live-stage --yes is intentionally explicit because it activates Safari, opens the controlled background page, creates/resizes an iTerm2 window, writes the ANSI pattern command into that session, and may require macOS Automation/Accessibility/Screen Recording permissions. It leaves the staged windows open for inspection.

term-chameleon sample --screen --output artifacts/adapt/screen.png
term-chameleon sample --screen --iterm-window --output artifacts/adapt/iterm-window.png
term-chameleon sample --screen --region 0,0,800,600 --output artifacts/adapt/region.png
term-chameleon adapt-once tests/fixtures/iterm/good-dark-glass.json --screen --dry-run
term-chameleon watch-live --dry-run --duration 10 --interval 1 --stable 2
term-chameleon watch-live --dry-run --iterm-window --duration 10 --interval 1 --stable 2
term-chameleon watch-live --yes --iterm-window --duration 30 --interval 2 --stable 3 --cooldown 10

Manual live smoke test, once iTerm2 is running and the Python API is enabled:

scripts/live-iterm-smoke.sh

Detect the current terminal and apply OSC color sequences for cross-terminal support (iTerm2, Kitty, Ghostty, Alacritty):

term-chameleon terminal-info
term-chameleon terminal-info --json
term-chameleon osc apply balanced
term-chameleon osc apply balanced --write
term-chameleon osc apply balanced --tmux
term-chameleon osc apply balanced --shell
term-chameleon osc reset

osc apply <preset> --write writes raw OSC 10/11/4 escape sequences directly to stdout for any OSC-capable terminal. Use --tmux inside a tmux session or --shell to get a printf-safe command. terminal-info reports the detected terminal type and capability flags.

Run the mode risk-classifier and hysteresis simulator:

term-chameleon watch-sim 0.2 0.8 0.5
term-chameleon watch-sim --stable 2 0.2 0.2 0.8 0.8

Run deterministic visual simulation:

term-chameleon visual-test tests/fixtures/iterm/good-dark-glass.json

Doctor a profile:

term-chameleon doctor tests/fixtures/iterm/bad-light-variant.json
term-chameleon doctor tests/fixtures/iterm/bad-light-variant.json --json

doctor --json emits machine-readable diagnostics after a profile loads successfully; profile load/parse errors still use the standard nonzero exit code with an error on stderr.

Preview fixes:

term-chameleon fix tests/fixtures/iterm/bad-light-variant.json --dry-run

Apply fixes to a copy:

cp tests/fixtures/iterm/bad-light-variant.json /tmp/profile.json
term-chameleon fix /tmp/profile.json --yes
term-chameleon doctor /tmp/profile.json

Troubleshooting

iTerm2 Python API not connected:

Ensure iTerm2 is running and Python API support is enabled: iTerm2 → Settings → General → Magic → check "Enable Python API". Run term-chameleon iterm-api-check to verify.

Screen Recording permission denied:

macOS requires Screen Recording permission for screencapture. Grant it in System Settings → Privacy & Security → Screen Recording for the terminal running Term Chameleon.

AutoLaunch daemon not starting:

Verify the script exists and is executable:

term-chameleon watch-daemon-status

If the PID file is stale (process not running), remove it and restart iTerm2:

rm ~/Library/Application\ Support/term-chameleon/watch-live.pid

Stale watcher process after uninstall:

uninstall-watch-daemon removes the AutoLaunch script but does not kill a running watcher. Stop it manually:

kill "$(cat ~/Library/Application\ Support/term-chameleon/watch-live.pid)"

Daemon CPU or disk usage:

The daemon defaults to a 10-second sampling interval and prunes artifacts to the 200 most recent. To reduce overhead further, increase the interval via config or --interval.

iTerm2 window bounds unavailable on startup:

The daemon defaults to whole-screen sampling for startup robustness. If using --iterm-window, the watcher waits up to 60 seconds for iTerm2 to create a window before failing.

Development

uv sync --extra dev
uv run pytest
uv run ruff check .

If you do not use uv:

python3 -m pytest
python3 -m term_chameleon.cli doctor tests/fixtures/iterm/bad-light-variant.json

Safety principles

• Static analysis before mutation.
• --dry-run support for fixes.
• Timestamped backups before writing.
• Deterministic JSON output.
• Explainable diagnostics and fixes.
• No direct mutation of ~/Library/Preferences/com.googlecode.iterm2.plist as the primary mechanism.

Positioning

Term Chameleon is not just another terminal theme and does not claim to invent automatic contrast. Prior art includes iTerm2 Minimum Contrast, Apple Terminal contrast tweaking, Ghostty minimum contrast, terminal opacity/blur settings, CSS blend-mode/backdrop approaches, and WCAG/APCA contrast engines.

The intended differentiated direction is a live contrast controller for translucent terminal windows: sample or infer the actual visual environment behind the terminal, then adapt palette, opacity, blur, and contrast to keep text readable without giving up the glass effect.