hook: the rewritten Bash command goes through two shell parses, which breaks quoting and compound commands

[idrmn]

Summary

secondwind hook prefixes the agent's Bash command with secondwind exec . exec then joins its argv with spaces and runs the result through sh -c. The command therefore passes two shell parses. Quoted metacharacters lose their quotes, and a compound command splits, so only its first segment reaches the optimizer.

Environment

• secondwind 0.3.2, built from git ab3888a with cargo install --git
• Claude Code 2.1.220, Arch Linux, fish 4.x as the user shell
• Hook installed with secondwind setup --hook

Repro 1: the quotes are lost

The agent runs this Bash command:

echo 'a|b'

Result:

sh: line 1: b: command not found

Expected output: a|b.

The outer shell parses secondwind exec echo 'a|b' and passes a|b as one argv item. exec rebuilds the string echo a|b and gives it to sh -c, where | is a pipe again.

Repro 2: a compound command splits

cd /tmp && pwd

Result: the original working directory, not /tmp.

The shell reads this as (secondwind exec cd /tmp) && pwd. The cd runs in the child process of secondwind and is lost. A variable assignment before ; is lost the same way. In a pipeline such as fd . | head -400, only fd is wrapped, so the recorded token count is the output before head, not the output the agent receives.

Impact

A Bash command with a quoted metacharacter fails. A command that depends on cd, on an assignment, or on a pipeline returns a wrong result, and the hook still reports success. The agent sees a shell error or wrong data, so the cause is hard to attribute to secondwind.

Code

• crates/cli/src/main.rs:869: format!("secondwind exec {command}")
• crates/cli/src/main.rs:880-884: command.join(" "), then sh -c
• crates/cli/src/main.rs:110-113: Exec { command: Vec<String> } with trailing_var_arg

Suggested fix

Keep one shell parse. Emit the command as a single argument from the hook, shell-quoted, and run that argument verbatim in exec with no join. For example secondwind exec --command '<quoted command>', where exec gives the value of --command to sh -c unchanged.