feat(cli): dump resolved SSH configuration

src/app/config_dump.rs

@@ -0,0 +1,59 @@
+// Copyright 2025 Lablup Inc. and Jeongkyu Shin
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+
+//! Side-effect-free resolved SSH configuration output.
+
+use std::io::Write as _;
+
+use anyhow::{Context, Result};
+use bssh::cli::SshDumpInvocation;
+use bssh::ssh::ssh_config::{SshConfig, render_resolved_config};
+
+/// Resolve and print ssh_config without initializing any connection services.
+pub async fn handle_config_dump(invocation: &SshDumpInvocation) -> Result<()> {
+    let mut config = match invocation.config_file.as_deref() {
+        Some(path) if path.as_os_str() == "none" => SshConfig::new(),
+        Some(path) => SshConfig::load_explicit_for_config_dump_with_options(
+            path,
+            &invocation.destination,
+            &invocation.overrides,
+        )
+        .await
+        .with_context(|| format!("Failed to load SSH config from {path:?}"))?,
+        None => {
+            SshConfig::load_default_for_config_dump_with_options(
+                &invocation.destination,
+                &invocation.overrides,
+            )
+            .await?
+        }
+    };
+    if invocation
+        .config_file
+        .as_deref()
+        .is_some_and(|path| path.as_os_str() == "none")
+    {
+        config
+            .apply_cli_options(&invocation.overrides)
+            .context("Failed to apply command-line SSH options")?;
+    }
+    if let Some(keyword) = config
+        .hosts
+        .iter()
+        .flat_map(|host| host.unknown_options.keys())
+        .next()
+    {
+        anyhow::bail!("Unknown SSH config option '{keyword}'");
+    }
+    let mut resolved = config.find_host_config(&invocation.destination);
+    if invocation.stdio_forward {
+        resolved.clear_all_forwardings.get_or_insert(true);
+        resolved.exit_on_forward_failure.get_or_insert(true);
+    }
+    let rendered = render_resolved_config(&invocation.destination, &resolved)?;
+    std::io::stdout()
+        .write_all(rendered.as_bytes())
+        .context("Failed to write resolved SSH configuration")
+}

src/app/mod.rs

@@ -18,6 +18,7 @@
 //! initialization, and utility functions for the bssh CLI.
 
 pub mod cache;
+pub mod config_dump;
 pub mod dispatcher;
 pub mod initialization;
 pub mod nodes;

src/app/query.rs

@@ -16,6 +16,22 @@
 
 use bssh::diagnosticln as eprintln;
 
+pub fn is_supported_query(query: &str) -> bool {
+    matches!(
+        query,
+        "cipher"
+            | "cipher-auth"
+            | "mac"
+            | "kex"
+            | "key"
+            | "key-plain"
+            | "key-cert"
+            | "key-sig"
+            | "protocol-version"
+            | "help"
+    )
+}
+
 /// Handle SSH query options (-Q)
 pub fn handle_query(query: &str) {
     match query {

src/cli/mod.rs

@@ -35,12 +35,14 @@
 
 mod bssh;
 pub mod pdsh;
+mod ssh_args;
 
 #[cfg(test)]
 mod mode_detection_tests;
 
 // Re-export main CLI types from bssh module
 pub use bssh::{Cli, Commands};
+pub use ssh_args::SshDumpInvocation;
 
 // Re-export pdsh compatibility utilities
 pub use pdsh::{