Switch LLM chat input to dialoguer and use ColorfulTheme everywhere

Replace raw stdin.lock().lines() in run_chat with dialoguer::Input
using spawn_blocking for TTY, with a stdin fallback for non-TTY.
Apply ColorfulTheme::default() to all dialoguer widgets in both
arc-llm and arc-workflows ConsoleInterviewer.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/arc-llm/Cargo.toml

@@ -28,6 +28,7 @@ base64.workspace = true
 bytes.workspace = true
 tokio-util.workspace = true
 clap.workspace = true
+dialoguer.workspace = true
 tracing.workspace = true
 arc-util = { path = "../arc-util" }
 

crates/arc-llm/src/cli.rs

@@ -1,4 +1,7 @@
-use std::io::{self, BufRead, IsTerminal, Read, Write};
+use std::io::{self, IsTerminal, Read, Write};
+
+use dialoguer::console::Term;
+use dialoguer::theme::ColorfulTheme;
 use std::time::Duration;
 
 use anyhow::{bail, Context, Result};
@@ -221,17 +224,28 @@ pub async fn run_chat(args: ChatArgs) -> Result<()> {
     eprintln!("Using model: {model_id}");
 
     let mut messages: Vec<Message> = Vec::new();
-    let stdin = io::stdin();
-    let mut lines = stdin.lock().lines();
+    let is_tty = io::stdin().is_terminal();
 
     loop {
-        eprint!("> ");
-        io::stderr().flush()?;
-
-        let line = match lines.next() {
-            Some(Ok(line)) => line,
-            Some(Err(e)) => return Err(e.into()),
-            None => break, // EOF
+        let line = if is_tty {
+            let result = tokio::task::spawn_blocking(|| {
+                dialoguer::Input::<String>::with_theme(&ColorfulTheme::default())
+                    .with_prompt(">")
+                    .interact_on(&Term::stderr())
+            })
+            .await?;
+            match result {
+                Ok(line) => line,
+                Err(_) => break,
+            }
+        } else {
+            eprint!("> ");
+            io::stderr().flush()?;
+            let mut buf = String::new();
+            if io::stdin().read_line(&mut buf)? == 0 {
+                break;
+            }
+            buf.trim_end().to_string()
         };
 
         let trimmed = line.trim();

crates/arc-workflows/src/interviewer/console.rs

@@ -3,6 +3,7 @@ use std::io::IsTerminal;
 use arc_util::terminal::Styles;
 use async_trait::async_trait;
 use dialoguer::console::Term;
+use dialoguer::theme::ColorfulTheme;
 use tokio::io::{AsyncBufReadExt, BufReader};
 
 use super::{Answer, AnswerValue, Interviewer, Question, QuestionType};
@@ -69,7 +70,7 @@ fn ask_select_interactive(question: &Question) -> Answer {
         all_items.push("Other (free text)...".to_string());
     }
 
-    let selection = dialoguer::Select::new()
+    let selection = dialoguer::Select::with_theme(&ColorfulTheme::default())
         .with_prompt(&question.text)
         .items(&all_items)
         .default(0)
@@ -78,7 +79,7 @@ fn ask_select_interactive(question: &Question) -> Answer {
     match selection {
         Ok(Some(idx)) if has_freeform && idx == question.options.len() => {
             // User chose the free-text option
-            dialoguer::Input::<String>::new()
+            dialoguer::Input::<String>::with_theme(&ColorfulTheme::default())
                 .with_prompt("Enter your response")
                 .interact_on(&Term::stderr())
                 .map_or_else(|_| Answer::skipped(), Answer::text)
@@ -103,7 +104,7 @@ fn ask_multi_select_interactive(question: &Question) -> Answer {
         .map(|opt| format!("{} - {}", opt.key, opt.label))
         .collect();
 
-    let selection = dialoguer::MultiSelect::new()
+    let selection = dialoguer::MultiSelect::with_theme(&ColorfulTheme::default())
         .with_prompt(&question.text)
         .items(&items)
         .interact_on_opt(&Term::stderr());
@@ -124,7 +125,7 @@ fn ask_multi_select_interactive(question: &Question) -> Answer {
 
 /// Ask a yes/no or confirmation question using dialoguer's `Confirm` widget on a TTY.
 fn ask_confirm_interactive(question: &Question) -> Answer {
-    let confirmed = dialoguer::Confirm::new()
+    let confirmed = dialoguer::Confirm::with_theme(&ColorfulTheme::default())
         .with_prompt(&question.text)
         .default(true)
         .interact_on_opt(&Term::stderr());
@@ -137,7 +138,7 @@ fn ask_confirm_interactive(question: &Question) -> Answer {
 
 /// Ask a freeform question using dialoguer's `Input` widget on a TTY.
 fn ask_freeform_interactive(question: &Question) -> Answer {
-    dialoguer::Input::<String>::new()
+    dialoguer::Input::<String>::with_theme(&ColorfulTheme::default())
         .with_prompt(&question.text)
         .interact_on(&Term::stderr())
         .map_or_else(|_| Answer::skipped(), Answer::text)