Color terminal-command prompt input like a running tool

[alejandro-ao]

Summary

When the prompt input starts with ! (or !!) — meaning submitting will run a shell command instead of messaging the model — the entire input text and the prompt's left border are now rendered in the theme's running-tool accent color, and the τ prompt prefix becomes a matching $ (roles.tool.border: amber #8a7a52 in tau-dark, #a16207 in tau-light, #ffd000 in high-contrast). Previously only the !/!! prefix itself was tinted with the theme accent color.

How it improves user experience

The ! prefix is easy to type accidentally or forget about while composing a longer command. Coloring the whole input, its left border, and a $ prompt prefix the same orange/amber as a tool while it is running gives an immediate, glanceable signal that the submission will execute in the shell, consistent with colors the user already associates with tool execution. Multi-line commands are fully colored too, and the color is derived from the active theme so custom themes stay consistent.

Issues

No tracking issue — small UX polish.

Manual validation

1. Run uv run tau (or python main.py equivalent / tau) and focus the prompt.
2. Type !pwd — the whole input and its left border turn amber/orange, and the τ prefix becomes a $ as soon as ! is the first character.
3. Add a second line (!echo a then newline + echo b) — both lines stay colored.
4. Delete the ! or type a normal message — input returns to the default prompt color.
5. While the agent runs, the prefix keeps the usual running animation; it returns to $ when idle in shell mode.
6. Compare with a running tool row in the transcript — the input color matches the running tool's accent color.
7. Switch themes (tau-dark, tau-light, high-contrast) and repeat — the input follows each theme's running-tool color.

Checks

• uv run pytest — 1145 passed
• uv run ruff check . — passed
• uv run ruff format --check . — passed
• uv run mypy — no issues