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feat(ui): add Shift+Tab shortcut to cycle between agents #2869

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f13e5a1
feat(ui): add Shift+Tab shortcut to cycle between agents
Lokimorty Apr 6, 2026
97c206c
fix: guard EchoGuard with cfg(unix) and check fcntl return before rea…
Lokimorty Apr 6, 2026
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69 changes: 66 additions & 3 deletions crates/forge_main/src/editor.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,13 +14,17 @@ use crate::model::ForgeCommandManager;
// TODO: Store the last `HISTORY_CAPACITY` commands in the history file
const HISTORY_CAPACITY: usize = 1024 * 1024;
const COMPLETION_MENU: &str = "completion_menu";
/// Zero-width space used as an invisible submit marker for Shift+Tab agent cycling.
/// This is an implementation detail — higher layers see `ReadResult::CycleAgent`.
const CYCLE_AGENT_MARKER: &str = "\u{200B}";

pub struct ForgeEditor {
editor: Reedline,
}

pub enum ReadResult {
Success(String),
CycleAgent,
Empty,
Continue,
Exit,
Expand Down Expand Up @@ -61,6 +65,20 @@ impl ForgeEditor {
ReedlineEvent::Edit(vec![EditCommand::InsertNewline]),
);

// on Shift+Tab press cycles to the next agent.
// Uses a proper Submit (not ExecuteHostCommand) so reedline correctly
// commits the prompt line. The zero-width space is invisible to the user
// but survives trim(), letting us distinguish this from an empty Enter.
let cycle = ReedlineEvent::Multiple(vec![
ReedlineEvent::Edit(vec![
EditCommand::Clear,
EditCommand::InsertString(CYCLE_AGENT_MARKER.to_string()),
]),
ReedlineEvent::Submit,
]);
keybindings.add_binding(KeyModifiers::SHIFT, KeyCode::BackTab, cycle.clone());
keybindings.add_binding(KeyModifiers::NONE, KeyCode::BackTab, cycle);

keybindings
}

Expand Down Expand Up @@ -100,8 +118,11 @@ impl ForgeEditor {
}

pub fn prompt(&mut self, prompt: &dyn Prompt) -> anyhow::Result<ReadResult> {
let signal = self.editor.read_line(prompt);
signal
// Discard any bytes buffered in stdin during agent execution
// (e.g. Shift+Tab presses) so they don't trigger actions.
drain_stdin();
self.editor
.read_line(prompt)
.map(Into::into)
.map_err(|e| anyhow::anyhow!(ReadLineError(e)))
}
Expand All @@ -113,6 +134,46 @@ impl ForgeEditor {
}
}

/// Reads and discards any bytes pending in stdin by briefly setting it to
/// non-blocking mode. This prevents buffered keypresses from agent execution
/// (like Shift+Tab) from being interpreted by reedline.
#[cfg(unix)]
fn drain_stdin() {
use std::io::Read;
use std::os::unix::io::AsRawFd;

unsafe extern "C" {
fn fcntl(fd: std::ffi::c_int, cmd: std::ffi::c_int, ...) -> std::ffi::c_int;
}

const F_GETFL: std::ffi::c_int = 3;
const F_SETFL: std::ffi::c_int = 4;
#[cfg(target_os = "linux")]
const O_NONBLOCK: std::ffi::c_int = 0o4000;
#[cfg(not(target_os = "linux"))]
const O_NONBLOCK: std::ffi::c_int = 0x0004;

let fd = std::io::stdin().as_raw_fd();
let flags = unsafe { fcntl(fd, F_GETFL) };
if flags < 0 {
return;
}

if unsafe { fcntl(fd, F_SETFL, flags | O_NONBLOCK) } < 0 {
return;
}

let mut buf = [0u8; 1024];
let mut stdin = std::io::stdin().lock();
while stdin.read(&mut buf).unwrap_or(0) > 0 {}
drop(stdin);

unsafe { fcntl(fd, F_SETFL, flags) };
}

#[cfg(not(unix))]
fn drain_stdin() {}

#[derive(Debug, thiserror::Error)]
#[error(transparent)]
pub struct ReadLineError(std::io::Error);
Expand All @@ -122,7 +183,9 @@ impl From<Signal> for ReadResult {
match signal {
Signal::Success(buffer) => {
let trimmed = buffer.trim();
if trimmed.is_empty() {
if trimmed == CYCLE_AGENT_MARKER {
ReadResult::CycleAgent
} else if trimmed.is_empty() {
ReadResult::Empty
} else {
ReadResult::Success(trimmed.to_string())
Expand Down
16 changes: 11 additions & 5 deletions crates/forge_main/src/input.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,12 @@ use crate::model::{ForgeCommandManager, SlashCommand};
use crate::prompt::ForgePrompt;
use crate::tracker;

/// What the user did at the prompt — either a command or a hotkey action.
pub enum PromptResult {
Command(SlashCommand),
CycleAgent,
}

/// Console implementation for handling user input via command line.
pub struct Console {
command: Arc<ForgeCommandManager>,
Expand All @@ -27,18 +33,18 @@ impl Console {
}

impl Console {
pub async fn prompt(&self, prompt: ForgePrompt) -> anyhow::Result<SlashCommand> {
pub async fn prompt(&self, prompt: ForgePrompt) -> anyhow::Result<PromptResult> {
loop {
let mut forge_editor = self.editor.lock().unwrap();
let user_input = forge_editor.prompt(&prompt)?;
drop(forge_editor);
match user_input {
ReadResult::Continue => continue,
ReadResult::Exit => return Ok(SlashCommand::Exit),
ReadResult::Empty => continue,
ReadResult::Continue | ReadResult::Empty => continue,
ReadResult::Exit => return Ok(PromptResult::Command(SlashCommand::Exit)),
ReadResult::CycleAgent => return Ok(PromptResult::CycleAgent),
ReadResult::Success(text) => {
tracker::prompt(text.clone());
return self.command.parse(&text);
return Ok(PromptResult::Command(self.command.parse(&text)?));
}
}
}
Expand Down
103 changes: 83 additions & 20 deletions crates/forge_main/src/ui.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ use crate::conversation_selector::ConversationSelector;
use crate::display_constants::{CommandType, headers, markers, status};
use crate::editor::ReadLineError;
use crate::info::Info;
use crate::input::Console;
use crate::input::{Console, PromptResult};
use crate::model::{ForgeCommandManager, SlashCommand};
use crate::porcelain::Porcelain;
use crate::prompt::ForgePrompt;
Expand All @@ -52,6 +52,34 @@ use crate::{TRACKER, banner, tracker};
// File-specific constants
const MISSING_AGENT_TITLE: &str = "<missing agent.title>";

/// RAII guard that suppresses terminal echo while alive.
/// Prevents keypresses during agent execution from disrupting spinner output.
#[cfg(unix)]
struct EchoGuard;

#[cfg(unix)]
impl EchoGuard {
fn suppress() -> Self {
let _ = std::process::Command::new("stty")
.arg("-echo")
.stdout(std::process::Stdio::null())
.stderr(std::process::Stdio::null())
.status();
Self
}
}

#[cfg(unix)]
impl Drop for EchoGuard {
fn drop(&mut self) {
let _ = std::process::Command::new("stty")
.arg("echo")
.stdout(std::process::Stdio::null())
.stderr(std::process::Stdio::null())
.status();
}
}
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@graphite-app graphite-app bot Apr 6, 2026

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The EchoGuard is not platform-guarded but uses Unix-specific stty command. On Windows, this will spawn a process that fails silently on every command execution, causing performance overhead.

Fix by adding platform guards:

#[cfg(unix)]
struct EchoGuard;

#[cfg(unix)]
impl EchoGuard {
    fn suppress() -> Self { /* ... */ }
}

#[cfg(unix)]
impl Drop for EchoGuard { /* ... */ }

#[cfg(not(unix))]
struct EchoGuard;

#[cfg(not(unix))]
impl EchoGuard {
    fn suppress() -> Self { Self }
}
Suggested change
/// RAII guard that suppresses terminal echo while alive.
/// Prevents keypresses during agent execution from disrupting spinner output.
struct EchoGuard;
impl EchoGuard {
fn suppress() -> Self {
let _ = std::process::Command::new("stty")
.arg("-echo")
.stdout(std::process::Stdio::null())
.stderr(std::process::Stdio::null())
.status();
Self
}
}
impl Drop for EchoGuard {
fn drop(&mut self) {
let _ = std::process::Command::new("stty")
.arg("echo")
.stdout(std::process::Stdio::null())
.stderr(std::process::Stdio::null())
.status();
}
}
/// RAII guard that suppresses terminal echo while alive.
/// Prevents keypresses during agent execution from disrupting spinner output.
#[cfg(unix)]
struct EchoGuard;
#[cfg(unix)]
impl EchoGuard {
fn suppress() -> Self {
let _ = std::process::Command::new("stty")
.arg("-echo")
.stdout(std::process::Stdio::null())
.stderr(std::process::Stdio::null())
.status();
Self
}
}
#[cfg(unix)]
impl Drop for EchoGuard {
fn drop(&mut self) {
let _ = std::process::Command::new("stty")
.arg("echo")
.stdout(std::process::Stdio::null())
.stderr(std::process::Stdio::null())
.status();
}
}
#[cfg(not(unix))]
struct EchoGuard;
#[cfg(not(unix))]
impl EchoGuard {
fn suppress() -> Self {
Self
}
}

Spotted by Graphite

Fix in Graphite

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/// Conversation dump format used by the /dump command
#[derive(Debug, serde::Deserialize, serde::Serialize)]
struct ConversationDump {
Expand Down Expand Up @@ -208,6 +236,21 @@ impl<A: API + ConsoleWriter + 'static, F: Fn() -> A + Send + Sync> UI<A, F> {
Ok(())
}

async fn on_cycle_agent(&mut self) -> Result<()> {
let mut agents = self.api.get_agents().await?;
agents.retain(|a| a.id != AgentId::SAGE);
agents.sort_by(|a, b| a.id.as_str().cmp(b.id.as_str()));

if agents.is_empty() {
return Ok(());
}

let current = self.api.get_active_agent().await.unwrap_or_default();
let idx = agents.iter().position(|a| a.id == current).unwrap_or(0);
let next = (idx + 1) % agents.len();
self.on_agent_change(agents[next].id.clone()).await
}

pub fn init(cli: Cli, f: F) -> Result<Self> {
// Parse CLI arguments first to get flags
let api = Arc::new(f());
Expand All @@ -228,26 +271,39 @@ impl<A: API + ConsoleWriter + 'static, F: Fn() -> A + Send + Sync> UI<A, F> {
})
}

async fn prompt(&self) -> Result<SlashCommand> {
// Get usage from current conversation if available
let usage = if let Some(conversation_id) = &self.state.conversation_id {
self.api
.conversation(conversation_id)
.await
.ok()
.flatten()
.and_then(|conv| conv.accumulated_usage())
} else {
None
};
async fn prompt(&mut self) -> Result<SlashCommand> {
loop {
// Get usage from current conversation if available
let usage = if let Some(conversation_id) = &self.state.conversation_id {
self.api
.conversation(conversation_id)
.await
.ok()
.flatten()
.and_then(|conv| conv.accumulated_usage())
} else {
None
};

// Prompt the user for input
let agent_id = self.api.get_active_agent().await.unwrap_or_default();
let model = self
.get_agent_model(self.api.get_active_agent().await)
.await;
let forge_prompt = ForgePrompt { cwd: self.state.cwd.clone(), usage, model, agent_id };
self.console.prompt(forge_prompt).await
// Prompt the user for input
let agent_id = self.api.get_active_agent().await.unwrap_or_default();
let model = self
.get_agent_model(self.api.get_active_agent().await)
.await;
let forge_prompt = ForgePrompt {
cwd: self.state.cwd.clone(),
usage,
model,
agent_id,
};

match self.console.prompt(forge_prompt).await? {
PromptResult::CycleAgent => {
self.on_cycle_agent().await?;
}
PromptResult::Command(command) => return Ok(command),
}
}
}

pub async fn run(&mut self) {
Expand Down Expand Up @@ -314,6 +370,12 @@ impl<A: API + ConsoleWriter + 'static, F: Fn() -> A + Send + Sync> UI<A, F> {
loop {
match command {
Ok(command) => {
// Suppress terminal echo so keypresses during execution
// (like Shift+Tab) don't disrupt the spinner output.
// Echo is restored when the guard is dropped.
#[cfg(unix)]
let _echo_guard = EchoGuard::suppress();

tokio::select! {
_ = tokio::signal::ctrl_c() => {
self.spinner.reset();
Expand All @@ -336,6 +398,7 @@ impl<A: API + ConsoleWriter + 'static, F: Fn() -> A + Send + Sync> UI<A, F> {
}
}

drop(_echo_guard);
self.spinner.stop(None)?;
}
Err(error) => {
Expand Down
3 changes: 3 additions & 0 deletions shell-plugin/lib/bindings.zsh
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Original file line number Diff line number Diff line change
Expand Up @@ -29,3 +29,6 @@ bindkey '^M' forge-accept-line
bindkey '^J' forge-accept-line
# Update the Tab binding to use the new completion widget
bindkey '^I' forge-completion # Tab for both @ and :command completion
# Bind Shift+Tab to cycle through agents
zle -N forge-cycle-agent
bindkey '\e[Z' forge-cycle-agent
32 changes: 32 additions & 0 deletions shell-plugin/lib/dispatcher.zsh
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,38 @@

# Main command dispatcher and widget registration

# Cycle to the next agent on Shift+Tab
function forge-cycle-agent() {
local commands_list=$(_forge_get_commands)
if [[ -z "$commands_list" ]]; then
return 0
fi

# Extract agent names (column 1) where type (column 2) is AGENT, excluding sage
local -a agents
agents=($(echo "$commands_list" | awk '$2 == "AGENT" && $1 != "sage" {print $1}' | sort))

if [[ ${#agents[@]} -le 0 ]]; then
return 0
fi

local current="${_FORGE_ACTIVE_AGENT:-forge}"
local next_agent="${agents[1]}"

local i
for i in {1..${#agents[@]}}; do
if [[ "${agents[$i]}" == "$current" ]]; then
local next_i=$(( (i % ${#agents[@]}) + 1 ))
next_agent="${agents[$next_i]}"
break
fi
done

_FORGE_ACTIVE_AGENT="$next_agent"
_forge_log info "\033[1;37m${_FORGE_ACTIVE_AGENT:u}\033[0m \033[90mis now the active agent\033[0m"
zle reset-prompt
}

# Action handler: Set active agent or execute command
# Flow:
# 1. Check if user_action is a CUSTOM command -> execute with `cmd` subcommand
Expand Down
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