feat(agent-input): !-prefix bash command mode

[chphch]

Adds a !-prefix bash command mode to the chat input, mirroring the Claude Code CLI: a message that starts with ! runs as a one-off shell command in the session's working directory instead of being sent to the agent, and its output renders inline. It's per-message only — there's no persistent mode toggle. The command runs over the existing session-scoped bash RPC (the same handler that powers directory autocomplete and Windows cmd support), so it executes in and is sandboxed to the session cwd; the echoed command and its output are injected as local-only messages (no server round-trip, the agent is never involved), with output shown in a fenced code block.

Proof

Captured locally via a standalone happy-server (PGlite) + Expo web + a paired happy-cli daemon, authenticated through the getDevWebQueryCredentials() dev URL bypass and driven headlessly with Playwright (live e2e — real daemon, real session). Typing !pwd and !echo BASHMODE_OK_4242 runs each as a shell command and renders the output in a sh code block; the agent is never invoked.

Verification: tsc --noEmit clean, and the new strings are added to all 10 locale files. No new message kind and no reducer changes — the output reuses the existing agent-text markdown rendering.

Related: addresses #568 (run shell commands from mobile without burning tokens). #597 proposes the same capability with a $ prefix; this uses ! to mirror the Claude Code CLI's bash mode.

[chphch]

Flagging an overlap so you don't have to work it out: #597 (@hztBUAA, opened 2026-02-13) answers the same request (#568) from the other side of the wire, and both PRs are sitting open. Here is the difference as I read it — I have no stake in which one lands.

	#597 — CLI-side	#1414 — app-side (this one)
Where the command runs	new execAsync in runClaude.ts, intercepted in specialCommands.ts before Claude sees the message	the session bash RPC that already exists (registerCommonHandlers.ts:176)
Size	2 files, +133/-4	5 source files (~100 lines) + the subtitle in 11 locales
Reaches	every client, since the interception is in the CLI	only where the app runs it
Ships via	a CLI release	an app build / OTA
Flag	always on	expBashMode, off by default
Prefixes	$ and !	$ and ! (just matched yours in 6d90e3b)
The output	goes through the session, so it persists and reaches your other devices	local-only messages — deliberately never sent, so it does not reach your other devices

Two honest notes, one each way:

• feat(cli): add direct shell command execution from mobile with $ prefix #597 covers more surfaces. Intercepting in the CLI means it works from the web app, the phone, and a second machine alike. Mine only works where the app itself runs the command, which is a real limitation rather than a footnote.
• Mine doesn't add a second place where we shell out. The bash RPC is already scoped to the session cwd and already carries the Windows windowsHide handling; feat(cli): add direct shell command execution from mobile with $ prefix #597 introduces a separate child_process.exec path alongside it. That's a maintenance argument, not something a user would feel.

The sharpest user-visible difference is the last row of the table: my output never leaves the device, which is what keeps it cheap, but it also means the command you ran isn't there when you pick the session up somewhere else. #597 doesn't have that gap.

Say the word and I'll close this in favour of #597 — no explanation needed.