feat: implement persistent CLI history with file storage

- Add Drop trait to InputSource for automatic history saving
- Replace DefaultHistory with FileHistory for persistence
- Store history in ~/.aws/amazonq/cli_history
- Refactor ChatHinter to use rustyline's built-in history search
- Remove manual history tracking in favor of rustyline's implementation
- Add history loading on startup with error handling
- Clean up unused hinter history update methods

Author: kkashilk

crates/chat-cli/src/cli/chat/input_source.rs

@@ -8,6 +8,7 @@ use super::prompt::{
 };
 #[cfg(unix)]
 use super::skim_integration::SkimCommandSelector;
+use crate::cli::chat::prompt::CLI_HISTORY_PATH;
 use crate::os::Os;
 
 #[derive(Debug)]
@@ -31,11 +32,33 @@ mod inner {
     }
 }
 
+impl Drop for InputSource {
+    fn drop(&mut self) {
+        self.save_history().unwrap();
+    }
+}
 impl InputSource {
     pub fn new(os: &Os, sender: PromptQuerySender, receiver: PromptQueryResponseReceiver) -> Result<Self> {
         Ok(Self(inner::Inner::Readline(rl(os, sender, receiver)?)))
     }
 
+    /// Save history to file
+    pub fn save_history(&mut self) -> Result<()> {
+        if let inner::Inner::Readline(rl) = &mut self.0 {
+            let history_path = dirs::home_dir()
+                .ok_or_else(|| eyre::eyre!("Could not find home directory"))?
+                .join(CLI_HISTORY_PATH);
+
+            // Create directory if it doesn't exist
+            if let Some(parent) = history_path.parent() {
+                std::fs::create_dir_all(parent)?;
+            }
+
+            rl.append_history(&history_path)?;
+        }
+        Ok(())
+    }
+
     #[cfg(unix)]
     pub fn put_skim_command_selector(
         &mut self,
@@ -78,12 +101,9 @@ impl InputSource {
                 let curr_line = rl.readline(prompt);
                 match curr_line {
                     Ok(line) => {
-                        let _ = rl.add_history_entry(line.as_str());
-
-                        if let Some(helper) = rl.helper_mut() {
-                            helper.update_hinter_history(&line);
+                        if Self::should_append_history(&line) {
+                            let _ = rl.add_history_entry(line.as_str());
                         }
-
                         Ok(Some(line))
                     },
                     Err(ReadlineError::Interrupted | ReadlineError::Eof) => Ok(None),
@@ -97,6 +117,18 @@ impl InputSource {
         }
     }
 
+    fn should_append_history(line: &str) -> bool {
+        let trimmed = line.trim().to_lowercase();
+        if trimmed.is_empty() {
+            return false;
+        }
+
+        if matches!(trimmed.as_str(), "y" | "n" | "t") {
+            return false;
+        }
+        true
+    }
+
     // We're keeping this method for potential future use
     #[allow(dead_code)]
     pub fn set_buffer(&mut self, content: &str) {

crates/chat-cli/src/cli/chat/prompt.rs

@@ -13,7 +13,10 @@ use rustyline::highlight::{
     Highlighter,
 };
 use rustyline::hint::Hinter as RustylineHinter;
-use rustyline::history::DefaultHistory;
+use rustyline::history::{
+    FileHistory,
+    SearchDirection,
+};
 use rustyline::validate::{
     ValidationContext,
     ValidationResult,
@@ -45,6 +48,8 @@ use super::tool_manager::{
 use crate::database::settings::Setting;
 use crate::os::Os;
 
+pub const CLI_HISTORY_PATH: &str = ".aws/amazonq/.cli_bash_history";
+
 pub const COMMANDS: &[&str] = &[
     "/clear",
     "/help",
@@ -262,31 +267,18 @@ impl Completer for ChatCompleter {
 
 /// Custom hinter that provides shadowtext suggestions
 pub struct ChatHinter {
-    /// Command history for providing suggestions based on past commands
-    history: Vec<String>,
     /// Whether history-based hints are enabled
     history_hints_enabled: bool,
 }
 
 impl ChatHinter {
     /// Creates a new ChatHinter instance
     pub fn new(history_hints_enabled: bool) -> Self {
-        Self {
-            history: Vec::new(),
-            history_hints_enabled,
-        }
+        Self { history_hints_enabled }
     }
 
-    /// Updates the history with a new command
-    pub fn update_history(&mut self, command: &str) {
-        let command = command.trim();
-        if !command.is_empty() && !command.contains('\n') && !command.contains('\r') {
-            self.history.push(command.to_string());
-        }
-    }
-
-    /// Finds the best hint for the current input
-    fn find_hint(&self, line: &str) -> Option<String> {
+    /// Finds the best hint for the current input using rustyline's history
+    fn find_hint(&self, line: &str, ctx: &Context<'_>) -> Option<String> {
         // If line is empty, no hint
         if line.is_empty() {
             return None;
@@ -300,13 +292,20 @@ impl ChatHinter {
                 .map(|cmd| cmd[line.len()..].to_string());
         }
 
-        // Try to find a hint from history if history hints are enabled
+        // Try to find a hint from rustyline's history if history hints are enabled
         if self.history_hints_enabled {
-            return self.history
-                .iter()
-                .rev() // Start from most recent
-                .find(|cmd| cmd.starts_with(line) && cmd.len() > line.len())
-                .map(|cmd| cmd[line.len()..].to_string());
+            let history = ctx.history();
+            let history_len = history.len();
+            if history_len == 0 {
+                return None;
+            }
+
+            if let Ok(Some(search_result)) = history.starts_with(line, history_len - 1, SearchDirection::Reverse) {
+                let entry = search_result.entry.to_string();
+                if entry.len() > line.len() {
+                    return Some(entry[line.len()..].to_string());
+                }
+            }
         }
 
         None
@@ -316,13 +315,13 @@ impl ChatHinter {
 impl RustylineHinter for ChatHinter {
     type Hint = String;
 
-    fn hint(&self, line: &str, pos: usize, _ctx: &Context<'_>) -> Option<Self::Hint> {
+    fn hint(&self, line: &str, pos: usize, ctx: &Context<'_>) -> Option<Self::Hint> {
         // Only provide hints when cursor is at the end of the line
         if pos < line.len() {
             return None;
         }
 
-        self.find_hint(line)
+        self.find_hint(line, ctx)
     }
 }
 
@@ -362,13 +361,6 @@ pub struct ChatHelper {
     validator: MultiLineValidator,
 }
 
-impl ChatHelper {
-    /// Updates the history of the ChatHinter with a new command
-    pub fn update_hinter_history(&mut self, command: &str) {
-        self.hinter.update_history(command);
-    }
-}
-
 impl Validator for ChatHelper {
     fn validate(&self, os: &mut ValidationContext<'_>) -> rustyline::Result<ValidationResult> {
         self.validator.validate(os)
@@ -426,7 +418,7 @@ pub fn rl(
     os: &Os,
     sender: PromptQuerySender,
     receiver: PromptQueryResponseReceiver,
-) -> Result<Editor<ChatHelper, DefaultHistory>> {
+) -> Result<Editor<ChatHelper, FileHistory>> {
     let edit_mode = match os.database.settings.get_string(Setting::ChatEditMode).as_deref() {
         Some("vi" | "vim") => EditMode::Vi,
         _ => EditMode::Emacs,
@@ -437,7 +429,6 @@ pub fn rl(
         .edit_mode(edit_mode)
         .build();
 
-    // Default to disabled if setting doesn't exist
     let history_hints_enabled = os
         .database
         .settings
@@ -452,6 +443,17 @@ pub fn rl(
     let mut rl = Editor::with_config(config)?;
     rl.set_helper(Some(h));
 
+    // Load history from ~/.aws/amazonq/cli_history
+    let history_path = dirs::home_dir()
+        .ok_or_else(|| eyre::eyre!("Could not find home directory"))?
+        .join(CLI_HISTORY_PATH);
+
+    if let Err(e) = rl.load_history(&history_path) {
+        if !matches!(e, ReadlineError::Io(ref io_err) if io_err.kind() == std::io::ErrorKind::NotFound) {
+            eprintln!("Warning: Failed to load history: {}", e);
+        }
+    }
+
     // Add custom keybinding for Alt+Enter to insert a newline
     rl.bind_sequence(
         KeyEvent(KeyCode::Enter, Modifiers::ALT),
@@ -487,6 +489,7 @@ pub fn rl(
 mod tests {
     use crossterm::style::Stylize;
     use rustyline::highlight::Highlighter;
+    use rustyline::history::DefaultHistory;
 
     use super::*;
 
@@ -694,11 +697,7 @@ mod tests {
 
     #[test]
     fn test_chat_hinter_history_hint_disabled() {
-        let mut hinter = ChatHinter::new(false);
-
-        // Add some history
-        hinter.update_history("Hello, world!");
-        hinter.update_history("How are you?");
+        let hinter = ChatHinter::new(false);
 
         // Test hint from history - should be None since history hints are disabled
         let line = "How";