diff --git a/crates/xtask/Cargo.toml b/crates/xtask/Cargo.toml
index 2e7cd1a..4343ed0 100644
--- a/crates/xtask/Cargo.toml
+++ b/crates/xtask/Cargo.toml
@@ -11,4 +11,4 @@ publish                = false
 [dependencies]
 clap.workspace          = true
 clap_complete.workspace = true
-eh.workspace = true
+eh.workspace            = true
diff --git a/crates/xtask/src/main.rs b/crates/xtask/src/main.rs
index ad449c4..a580cda 100644
--- a/crates/xtask/src/main.rs
+++ b/crates/xtask/src/main.rs
@@ -42,6 +42,7 @@ enum Binary {
   Nr,
   Ns,
   Nb,
+  Nu,
 }
 
 impl Binary {
@@ -50,6 +51,7 @@ impl Binary {
       Self::Nr => "nr",
       Self::Ns => "ns",
       Self::Nb => "nb",
+      Self::Nu => "nu",
     }
   }
 }
@@ -90,7 +92,7 @@ fn create_multicall_binaries(
     );
   }
 
-  let multicall_binaries = [Binary::Nr, Binary::Ns, Binary::Nb];
+  let multicall_binaries = [Binary::Nr, Binary::Ns, Binary::Nb, Binary::Nu];
   let bin_path = Path::new(bin_dir);
 
   for binary in multicall_binaries {
@@ -153,7 +155,7 @@ fn generate_completions(
   println!("completion file generated: {}", completion_file.display());
 
   // Create symlinks for multicall binaries
-  let multicall_names = ["nb", "nr", "ns"];
+  let multicall_names = ["nb", "nr", "ns", "nu"];
   for name in &multicall_names {
     let symlink_path = output_dir.join(format!("{name}.{shell}"));
     if symlink_path.exists() {
diff --git a/eh/Cargo.toml b/eh/Cargo.toml
index d221297..92dd751 100644
--- a/eh/Cargo.toml
+++ b/eh/Cargo.toml
@@ -11,10 +11,12 @@ crate-type = [ "lib" ]
 name       = "eh"
 
 [dependencies]
-clap.workspace               = true
-eh-log.workspace             = true
-regex.workspace              = true
-tempfile.workspace           = true
-thiserror.workspace          = true
-walkdir.workspace            = true
-yansi.workspace              = true
+clap.workspace       = true
+dialoguer.workspace  = true
+eh-log.workspace     = true
+regex.workspace      = true
+serde_json.workspace = true
+tempfile.workspace   = true
+thiserror.workspace  = true
+walkdir.workspace    = true
+yansi.workspace      = true
diff --git a/eh/src/error.rs b/eh/src/error.rs
index 909453a..9ebc9b6 100644
--- a/eh/src/error.rs
+++ b/eh/src/error.rs
@@ -45,6 +45,15 @@ pub enum EhError {
 
   #[error("invalid input '{input}': {reason}")]
   InvalidInput { input: String, reason: String },
+
+  #[error("failed to parse JSON from nix output: {detail}")]
+  JsonParse { detail: String },
+
+  #[error("no flake inputs found in lock file")]
+  NoFlakeInputs,
+
+  #[error("no inputs selected")]
+  UpdateCancelled,
 }
 
 pub type Result<T> = std::result::Result<T, EhError>;
@@ -65,6 +74,9 @@ impl EhError {
       Self::Utf8(_) => 10,
       Self::Timeout { .. } => 11,
       Self::PreEvalFailed { .. } => 12,
+      Self::JsonParse { .. } => 13,
+      Self::NoFlakeInputs => 14,
+      Self::UpdateCancelled => 0,
     }
   }
 
@@ -92,12 +104,19 @@ impl EhError {
       Self::InvalidInput { .. } => {
         Some("avoid shell metacharacters in nix arguments")
       },
+      Self::JsonParse { .. } => {
+        Some("ensure 'nix flake metadata --json' produces valid output")
+      },
+      Self::NoFlakeInputs => {
+        Some("run this from a directory with a flake.lock that has inputs")
+      },
       Self::Io(_)
       | Self::Regex(_)
       | Self::Utf8(_)
       | Self::HashFixFailed { .. }
       | Self::ProcessExit { .. }
-      | Self::CommandFailed { .. } => None,
+      | Self::CommandFailed { .. }
+      | Self::UpdateCancelled => None,
     }
   }
 }
@@ -156,6 +175,15 @@ mod tests {
       12
     );
     assert_eq!(EhError::ProcessExit { code: 42 }.exit_code(), 42);
+    assert_eq!(
+      EhError::JsonParse {
+        detail: "x".into(),
+      }
+      .exit_code(),
+      13
+    );
+    assert_eq!(EhError::NoFlakeInputs.exit_code(), 14);
+    assert_eq!(EhError::UpdateCancelled.exit_code(), 0);
   }
 
   #[test]
@@ -221,6 +249,14 @@ mod tests {
       .hint()
       .is_some()
     );
+    assert!(
+      EhError::JsonParse {
+        detail: "x".into(),
+      }
+      .hint()
+      .is_some()
+    );
+    assert!(EhError::NoFlakeInputs.hint().is_some());
     // Variants without hints
     assert!(
       EhError::CommandFailed {
@@ -230,5 +266,6 @@ mod tests {
       .is_none()
     );
     assert!(EhError::ProcessExit { code: 1 }.hint().is_none());
+    assert!(EhError::UpdateCancelled.hint().is_none());
   }
 }
diff --git a/eh/src/lib.rs b/eh/src/lib.rs
index 5dd2c7b..23c5e78 100644
--- a/eh/src/lib.rs
+++ b/eh/src/lib.rs
@@ -3,6 +3,7 @@ pub mod command;
 pub mod error;
 pub mod run;
 pub mod shell;
+pub mod update;
 pub mod util;
 
 pub use clap::{CommandFactory, Parser, Subcommand};
@@ -34,4 +35,9 @@ pub enum Command {
     #[arg(trailing_var_arg = true)]
     args: Vec<String>,
   },
+  /// Update flake inputs interactively
+  Update {
+    #[arg(trailing_var_arg = true)]
+    args: Vec<String>,
+  },
 }
diff --git a/eh/src/main.rs b/eh/src/main.rs
index 8cc4d11..8ce8b6b 100644
--- a/eh/src/main.rs
+++ b/eh/src/main.rs
@@ -9,6 +9,7 @@ mod command;
 mod error;
 mod run;
 mod shell;
+mod update;
 mod util;
 
 fn main() {
@@ -17,11 +18,14 @@ fn main() {
   match result {
     Ok(code) => std::process::exit(code),
     Err(e) => {
-      eh_log::log_error!("{e}");
-      if let Some(hint) = e.hint() {
-        eh_log::log_hint!("{hint}");
+      let code = e.exit_code();
+      if code != 0 {
+        eh_log::log_error!("{e}");
+        if let Some(hint) = e.hint() {
+          eh_log::log_hint!("{hint}");
+        }
       }
-      std::process::exit(e.exit_code());
+      std::process::exit(code);
     },
   }
 }
@@ -37,6 +41,7 @@ fn dispatch_multicall(
     "nr" => "run",
     "ns" => "shell",
     "nb" => "build",
+    "nu" => "update",
     _ => return None,
   };
 
@@ -60,6 +65,10 @@ fn dispatch_multicall(
     return Some(Ok(0));
   }
 
+  if subcommand == "update" {
+    return Some(update::handle_update(&rest));
+  }
+
   let hash_extractor = util::RegexHashExtractor;
   let fixer = util::DefaultNixFileFixer;
   let classifier = util::DefaultNixErrorClassifier;
@@ -110,6 +119,8 @@ fn run_app() -> Result<i32> {
       build::handle_nix_build(&args, &hash_extractor, &fixer, &classifier)
     },
 
+    Some(Command::Update { args }) => update::handle_update(&args),
+
     None => {
       Cli::command().print_help()?;
       println!();
diff --git a/eh/src/update.rs b/eh/src/update.rs
new file mode 100644
index 0000000..df4184e
--- /dev/null
+++ b/eh/src/update.rs
@@ -0,0 +1,115 @@
+use crate::{
+  command::{NixCommand, StdIoInterceptor},
+  error::{EhError, Result},
+};
+
+/// Parse flake input names from `nix flake metadata --json` output.
+pub fn parse_flake_inputs(stdout: &str) -> Result<Vec<String>> {
+  let value: serde_json::Value =
+    serde_json::from_str(stdout).map_err(|e| EhError::JsonParse {
+      detail: e.to_string(),
+    })?;
+
+  let inputs = value
+    .get("locks")
+    .and_then(|l| l.get("nodes"))
+    .and_then(|n| n.get("root"))
+    .and_then(|r| r.get("inputs"))
+    .and_then(|i| i.as_object())
+    .ok_or(EhError::NoFlakeInputs)?;
+
+  let mut names: Vec<String> = inputs.keys().cloned().collect();
+  names.sort();
+  Ok(names)
+}
+
+/// Fetch flake input names by running `nix flake metadata --json`.
+fn fetch_flake_inputs() -> Result<Vec<String>> {
+  let output = NixCommand::new("flake")
+    .arg("metadata")
+    .arg("--json")
+    .print_build_logs(false)
+    .output()?;
+
+  let stdout = String::from_utf8(output.stdout)?;
+  parse_flake_inputs(&stdout)
+}
+
+/// Prompt the user to select inputs via a multi-select dialog.
+fn prompt_input_selection(inputs: &[String]) -> Result<Vec<String>> {
+  let selections = dialoguer::MultiSelect::new()
+    .with_prompt("Select inputs to update")
+    .items(inputs)
+    .interact()
+    .map_err(|e| EhError::Io(std::io::Error::other(e)))?;
+
+  if selections.is_empty() {
+    return Err(EhError::UpdateCancelled);
+  }
+
+  Ok(selections.iter().map(|&i| inputs[i].clone()).collect())
+}
+
+/// Entry point for the `update` subcommand.
+///
+/// If `args` is non-empty, use them as explicit input names.
+/// Otherwise, fetch inputs interactively and prompt for selection.
+pub fn handle_update(args: &[String]) -> Result<i32> {
+  let selected = if args.is_empty() {
+    let inputs = fetch_flake_inputs()?;
+    if inputs.is_empty() {
+      return Err(EhError::NoFlakeInputs);
+    }
+    prompt_input_selection(&inputs)?
+  } else {
+    args.to_vec()
+  };
+
+  let mut cmd = NixCommand::new("flake").arg("lock");
+  for name in &selected {
+    cmd = cmd.arg("--update-input").arg(name);
+  }
+
+  eh_log::log_info!("updating inputs: {}", selected.join(", "));
+
+  let status = cmd.run_with_logs(StdIoInterceptor)?;
+  Ok(status.code().unwrap_or(1))
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn test_parse_flake_inputs() {
+    let json = r#"{
+      "locks": {
+        "nodes": {
+          "root": {
+            "inputs": {
+              "nixpkgs": "nixpkgs_2",
+              "home-manager": "home-manager_2",
+              "flake-utils": "flake-utils_2"
+            }
+          }
+        }
+      }
+    }"#;
+
+    let inputs = parse_flake_inputs(json).unwrap();
+    assert_eq!(inputs, vec!["flake-utils", "home-manager", "nixpkgs"]);
+  }
+
+  #[test]
+  fn test_parse_flake_inputs_invalid_json() {
+    let result = parse_flake_inputs("not json");
+    assert!(result.is_err());
+  }
+
+  #[test]
+  fn test_parse_flake_inputs_no_inputs() {
+    let json = r#"{"locks": {"nodes": {"root": {}}}}"#;
+    let result = parse_flake_inputs(json);
+    assert!(matches!(result, Err(EhError::NoFlakeInputs)));
+  }
+}