[eric-engberg]

What

A Fast Mode widget shows whether Claude Code's fast mode is on. By default it renders ⚡ on or ⚡ off; f cycles to an icon with a state dot (⚡ ◉ / ⚡ ○), plain text (on / off) and fast on / fast off, and n swaps in Nerd Font flash icons. Its hide option, "when fast mode is off", leaves only the on state on the line.

Why

Claude Code reports fast mode in the status line payload, but nothing in ccstatusline showed it:

{ "model": { "id": "claude-opus-4-6", "display_name": "Opus 4.6" }, "fast_mode": true }

Fast mode changes how quickly and expensively a session runs, and it's easy to lose track of after toggling it with /fast. The status line is the natural place to see it, next to the model and effort.

How

• src/widgets/FastMode.ts follows Voice Status: the same shared format-options helpers for f and n, the same raw value behavior (only the label part goes: on / off, or the state dot or icon in the icon format), and the same Nerd Font rules (n is offered only where an icon shows). The Nerd Font pair is nf-md-flash / nf-md-flash_off.
• The hide option uses the existing hideable-state mechanism (h in the line editor), off by default, so the widget shows both states unless you choose otherwise.
• It reads fast_mode from the payload only: no settings files, no transcript, no subprocess. Without the field (older Claude Code versions), it renders nothing.
• fast_mode is added to StatusJSONSchema as an optional, nullable boolean. A malformed value is dropped instead of failing validation, since a schema failure blanks the whole status line for a field only this widget reads.
• The TUI preview shows the on state, as Voice Status does.
• Docs: a Fast Mode entry in the widget list and its keys in the shortcuts list (docs/USAGE.md).

Demo

Adding Fast Mode with the picker's search, then cycling its formats with f (icon, text, word, back to icon plus text) and turning on the Nerd Font icon with n. The preview shows the widget's sample, on.

Powerline

Plain

Piped through the real CLI with fast_mode true, false and absent. Line 1 uses the default format; line 2 uses fast on/off with "when fast mode is off" checked, so it drops out when fast mode is off. VHS's terminal draws ⚡ as a narrow text glyph, so it looks followed by an extra space here; terminals that draw it as an emoji (iTerm2, Terminal.app, Ghostty, kitty, WezTerm) show ⚡ on.

Powerline

Plain

Testing

• bun run lint passes; bun test: 3213 pass, 0 fail across 179 files.
• New tests: src/widgets/__tests__/FastMode.test.ts (metadata, keybinds, every format on and off with and without the Nerd Font icon, raw value in every format, hide when off, preview, missing or null fast_mode) and three StatusJSON tests (true, null, and a malformed value dropped while the rest of the payload parses).
• Under Node (Vitest 5, Node 26.10.0): the new and related test files pass, 60 of 60. The full suite fails the same 186 tests in the same 18 files as main (all from spying on Node built-ins); no new failing files.
• Built CLI under Bun 1.4.2 and Node 26.10.0: with the baseline configs, all runtimes agree and match main in plain and Powerline modes; with a Fast Mode config and fast_mode true and false, all runtimes agree byte for byte (⚡ on / ⚡ off, and the hidden-when-off widget drops out). The TUI opens and exits cleanly under both.