Module io_writer 

Public API

CliOutput is the parameterized output abstraction every cmd_* handler writes to. It owns mutable references to dyn Write for both stdout and stderr so production code can pass io::stdout() / io::stderr() locks while unit tests pass Vec<u8> capture buffers.

The struct is the stable contract between W5a (this module) and the downstream cmd_* migrations in W5b/c/d. Do not change the field visibility or method signatures without coordinating across closers.

Stable surface

pub struct CliOutput<'a> {
    pub stdout: &'a mut dyn Write,
    pub stderr: &'a mut dyn Write,
}

impl<'a> CliOutput<'a> {
    pub fn from_std(stdout: &'a mut dyn Write, stderr: &'a mut dyn Write) -> Self;
}

Usage in handlers

Every cmd_* replaces println!(...) with writeln!(out.stdout, ...)? and eprintln!(...) with writeln!(out.stderr, ...)?. The ? propagates I/O errors instead of panicking on broken-pipe (closing a long-running pager mid-output, etc.).

Structs

CliOutput

Output abstraction passed to every CLI command. Carries mutable references to stdout and stderr writers so handlers can be unit-tested by capturing into Vec<u8> buffers.