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d o t c o m j a c k

claude-session-tint

Know which Claude Code session needs you.

Tag a terminal window with a project. It wears that project's color quietly while it works, lights up when a response lands, and drops back the moment you look at it.

If you run one Claude Code session, you do not need this. If you run eight, you are currently alt-tabbing through all of them to find the one that finished.

,api        tag this window "API"        (no turn, no tokens, no reply)
,           show the palette
,off        untag

---

The part worth stealing even if you never install this

,api runs a command from inside a live Claude Code session without invoking the model. No turn, no tokens, no assistant message in your transcript. The window just changes color.

That is a UserPromptSubmit hook returning a blocking decision:

{
  "decision": "block",
  "reason": "<what to show the user>",
  "hookSpecificOutput": {
    "hookEventName": "UserPromptSubmit",
    "suppressOriginalPrompt": true
  }
}

Claude Code sees the blocking decision and never queries the model. reason is shown to you directly. suppressOriginalPrompt stops your ,api from being echoed back into the transcript.

Two details that are easy to get wrong:

• The hook must be synchronous. The async flag's own schema reads "If true, hook runs in background without blocking", so an async hook returns after the prompt has already gone to the model and cannot gate anything. Nothing warns you. It just stops working.
• Exit 2 as well as printing the JSON. With exit 0 you take a success branch that tacks a "completed" line onto your output and reports the outcome as success. Exit 2 skips it, and since decision: "block" has already set the blocking error, the [<command>]: <stderr> wrapper never replaces your text either.

You can use this shape for any in-session command: toggling a flag, bumping a counter, kicking off a build. prompt-hook.sh is 100 lines and is the whole pattern.

One caveat worth knowing before you build on it. The gate only fires on a prompt you submit at an idle input box. If you type ,api while a turn is already running, the message is delivered to the model mid-turn and never reaches UserPromptSubmit at all, so it lands in the transcript as an ordinary prompt and costs a turn. That is a property of the hook, not of this script, and it applies to any UserPromptSubmit command you write. Wait for the turn to finish.

---

What it looks like

State	Window
Idle, tagged api	body washed 22% toward that project's color
Response finished, you were elsewhere	jumps to 48%, clearly lit
You focus the window	back to 22% within about a second
Untagged	stays your normal background, still lights neutral grey when unread

Because it paints the window body, lit windows are obvious in Mission Control and cmd-tab, not just when the window is already visible.

Multiple tabs in one window

Terminal draws only the selected tab's body, and it gives the tab bar no colour of its own. So painting a background tab would be invisible exactly when you need it, and selecting that tab would clear it before you ever saw it.

For a tab that shares a window, the signal moves to the one thing that does reach the tab bar: a dot in front of the tab title.

  ● api          <- finished, you have not looked
    web
    docs         <- selected

The dot is stripped the moment you select the tab. It is never stored anywhere: a zero-width sentinel marks our own prefix so it can be removed without keeping a copy of your title, which means it can never overwrite something you set with /rename. Change the glyph with TABTINT_MARK.

One-tab windows are unaffected and still get the colour wash.

If you do not see the dot, your profile has the title turned off: Terminal > Settings > Profiles > Window > Title, enable "Custom title". AppleScript cannot read that checkbox, so the tool cannot warn you automatically.

---

Terminal support, honestly

Terminal	Window coloring	,project zero-turn command
macOS Terminal.app	yes, tested	yes
iTerm2, Ghostty, kitty, WezTerm	no	yes
Linux, Windows	no	yes

The coloring drives Terminal.app through AppleScript, so it is macOS only. It degrades to a silent no-op elsewhere rather than erroring.

If you use iTerm2, Ghostty, or kitty you likely do not want this half anyway: those terminals have native tab colors, which Terminal.app has never had. This exists because Terminal.app gives you exactly one lever, the session background color, and no way to color a tab. See "Adding a terminal" below.

---

Install

Requires macOS and Claude Code.

As a plugin (recommended). From inside Claude Code:

/plugin marketplace add dotcomjack/claude-session-tint
/plugin install claude-session-tint@dotcomjack

That is the whole install. Hooks and the /tabtint command register themselves, and a starter palette ships with the plugin, so there is nothing to copy and no settings file to edit. Uninstall with /plugin uninstall claude-session-tint.

Your palette lives at ~/.claude/tabtint-palette.conf, outside the plugin directory, so it survives plugin updates.

Homebrew, if you only want the tabtint shell command:

brew install dotcomjack/tap/claude-session-tint

That gives you the command but not the hooks, so windows will not light up on their own until you also install the plugin above.

Manual install instead (no plugin system, adds a shell command)

Requires jq.

git clone https://github.com/dotcomjack/claude-session-tint.git
cd claude-session-tint
./install.sh

The installer merges into ~/.claude/settings.json, it does not replace it. Your existing hooks are preserved, the file is backed up to settings.json.bak-tabtint first, and the result is validated as JSON before anything is written. Re-running is safe.

./install.sh --uninstall     # restores every window it touched, then removes itself

The plugin puts tabtint on the Bash tool's PATH. To also use it from your own shell, symlink it:

ln -sf ~/.claude/plugins/cache/dotcomjack/claude-session-tint/*/bin/tabtint ~/.local/bin/tabtint

---

Use

Edit ~/.claude/tabtint-palette.conf with your projects:

#HEX	KEY	LABEL	EMOJI
#A3D8E1	api	API	🔵
#6FB07A	web	Web	🌿

Tab separated. HEX is the identity color at full strength, never painted at full strength. EMOJI is optional, see below.

Then, from inside a Claude Code session:

,api            tag this window
,               palette plus what this window is
,off            untag, restore original background
,idle off       only light up on unread, no resting tint

Or from a shell: tabtint api, tabtint list, tabtint sync, tabtint status.

Tuning

export TABTINT_IDLE_PCT=30    # resting tint, default 22
export TABTINT_ATTN_PCT=55    # unread, default 48
tabtint sync

Below about 15% everything collapses toward black and the colors stop being tellable apart. That is a property of washing a color over a dark background, not a bug.

The emoji column

No terminal here lets you color the tab chrome, but every terminal renders an emoji in the tab title. Tagging a window copies a ready line to your clipboard:

/rename 🔵 API

Paste it and the tab bar itself carries a marker. Claude Code owns the title, so this hands you the line instead of fighting it for control.

---

How it works

• Stop hook: response finished. If the window is not focused, paint it lit.
• UserPromptSubmit hook: you typed something here, so drop back to resting.
• SessionStart hook: apply the resting state.
• One shared watcher polls for the focused window and clears it, then exits when nothing is lit. It polls at 1Hz for the first 12 seconds after anything lights up, then backs off to 3s.

State lives in ~/.claude/state/tabtint/, one small file per tty. Each window's true original background is captured once, before anything is painted, so uninstalling always restores exactly what you had.

Privacy

No network calls anywhere. Nothing writes your prompt text to disk. The UserPromptSubmit hook does receive every prompt you type, which is inherent to that hook type, but it pattern-matches and discards. When it does intercept a ,project line, the model is never invoked, so that text does not leave your machine at all.

---

Adding a terminal

tabtint.sh isolates every terminal interaction in four functions: focused_tty, read_bg, write_bg, and all_ttys. Porting to a terminal with native tab colors means replacing those. For iTerm2 that is an escape sequence rather than AppleScript, and for kitty it is kitty @ set-tab-color. PRs welcome.

---

License

MIT. Built by DotcomJack.