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fix(shim): hold registry lock across load-modify-save to prevent pane ID races #640

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Merged
Wirasm merged 3 commits into from
Mar 23, 2026
Merged

fix(shim): hold registry lock across load-modify-save to prevent pane ID races #640

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46a8f7b
fix(shim): hold registry lock across load-modify-save to prevent pane…
Wirasm Mar 19, 2026
c63db2a
fix(shim): gate standalone load() behind #[cfg(test)], keep save() fo…
Wirasm Mar 19, 2026
a9813ec
fix(shim): address review findings from PR #640
Wirasm Mar 23, 2026
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113 changes: 64 additions & 49 deletions crates/kild-tmux-shim/src/commands.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -300,28 +300,41 @@ fn handle_split_window(args: SplitWindowArgs<'_>) -> Result<i32, ShimError> {
);

let sid = session_id()?;
let mut registry = state::load(&sid)?;
let mut locked = state::load_and_lock(&sid)?;

// Determine which window the target pane belongs to
let parent_pane_id = resolve_pane_id(args.target);
let window_id = registry
let window_id = locked
.registry()
.panes
.get(&parent_pane_id)
.map(|p| p.window_id.clone())
.unwrap_or_else(|| "0".to_string());

let pane_id = create_pty_pane(&mut registry, &window_id, &args.command)?;
state::save(&sid, &registry)?;
let pane_id = create_pty_pane(locked.registry_mut(), &window_id, &args.command)?;

if args.print_info {
let fmt = args.format.unwrap_or("#{pane_id}");
let session_name = &registry.session_name;
let window_name = registry
// Capture format values before save consumes the guard (only when needed)
let print_values = if args.print_info {
let session_name = locked.registry().session_name.clone();
let window_name = locked
.registry()
.windows
.get(&window_id)
.map(|w| w.name.as_str())
.unwrap_or("main");
let output = expand_format(fmt, &pane_id, session_name, &window_id, window_name, "");
.map(|w| w.name.clone())
.unwrap_or_else(|| "main".to_string());
Some((
args.format.unwrap_or("#{pane_id}"),
session_name,
window_name,
))
} else {
None
};

locked.save()?;

if let Some((fmt, session_name, window_name)) = print_values {
let output = expand_format(fmt, &pane_id, &session_name, &window_id, &window_name, "");
println!("{}", output);
}

Expand Down Expand Up @@ -451,10 +464,11 @@ fn handle_kill_pane(args: KillPaneArgs<'_>) -> Result<i32, ShimError> {
debug!(event = "shim.kill_pane_started", target = ?args.target);

let sid = session_id()?;
let mut registry = state::load(&sid)?;
let mut locked = state::load_and_lock(&sid)?;

let pane_id = resolve_pane_id(args.target);
let pane = registry
let pane = locked
.registry()
.panes
.get(&pane_id)
.ok_or_else(|| ShimError::state(format!("pane {} not found in registry", pane_id)))?;
Expand Down Expand Up @@ -492,8 +506,8 @@ fn handle_kill_pane(args: KillPaneArgs<'_>) -> Result<i32, ShimError> {
}
}

registry.remove_pane(&pane_id);
state::save(&sid, &registry)?;
locked.registry_mut().remove_pane(&pane_id);
locked.save()?;

debug!(event = "shim.kill_pane_completed", pane_id = pane_id);
Ok(0)
Expand Down Expand Up @@ -574,17 +588,17 @@ fn handle_select_pane(args: SelectPaneArgs<'_>) -> Result<i32, ShimError> {
// Only need state if we have style or title to store
if args.style.is_some() || args.title.is_some() {
let sid = session_id()?;
let mut registry = state::load(&sid)?;
let mut locked = state::load_and_lock(&sid)?;
let pane_id = resolve_pane_id(args.target);

if let Some(pane) = registry.panes.get_mut(&pane_id) {
if let Some(pane) = locked.registry_mut().panes.get_mut(&pane_id) {
if let Some(style) = args.style {
pane.border_style = style.to_string();
}
if let Some(title) = args.title {
pane.title = title.to_string();
}
state::save(&sid, &registry)?;
locked.save()?;
}
}

Expand All @@ -604,15 +618,15 @@ fn handle_set_option(args: SetOptionArgs<'_>) -> Result<i32, ShimError> {
// Store pane-scoped options in the pane entry
if matches!(args.scope, OptionScope::Pane) {
let sid = session_id()?;
let mut registry = state::load(&sid)?;
let mut locked = state::load_and_lock(&sid)?;
let pane_id = resolve_pane_id(args.target);

if let Some(pane) = registry.panes.get_mut(&pane_id) {
if let Some(pane) = locked.registry_mut().panes.get_mut(&pane_id) {
// Store known pane options
if args.key == "pane-border-style" || args.key.ends_with("-style") {
pane.border_style = args.value;
}
state::save(&sid, &registry)?;
locked.save()?;
}
}

Expand Down Expand Up @@ -655,21 +669,21 @@ fn handle_new_session(args: NewSessionArgs<'_>) -> Result<i32, ShimError> {
debug!(event = "shim.new_session_started", name = ?args.session_name);

let sid = session_id()?;
let mut registry = state::load(&sid)?;
let mut locked = state::load_and_lock(&sid)?;

// Read phase: derive names and IDs from current state
let session_name = args
.session_name
.map(|s| s.to_string())
.unwrap_or_else(|| format!("kild_{}", registry.sessions.len()));

.unwrap_or_else(|| format!("kild_{}", locked.registry().sessions.len()));
let window_name = args
.window_name
.map(|s| s.to_string())
.unwrap_or_else(|| "main".to_string());
let window_id = format!("{}", locked.registry().windows.len());

// Allocate a new window
let window_id = format!("{}", registry.windows.len());
registry.windows.insert(
// Write phase: mutate registry
locked.registry_mut().windows.insert(
window_id.clone(),
WindowEntry {
name: window_name,
Expand All @@ -678,18 +692,18 @@ fn handle_new_session(args: NewSessionArgs<'_>) -> Result<i32, ShimError> {
);

// Create initial pane in the new window
let pane_id = create_pty_pane(&mut registry, &window_id, &[])?;
let pane_id = create_pty_pane(locked.registry_mut(), &window_id, &[])?;

// Register session
registry.sessions.insert(
locked.registry_mut().sessions.insert(
session_name.clone(),
SessionEntry {
name: session_name.clone(),
windows: vec![window_id],
},
);

state::save(&sid, &registry)?;
locked.save()?;

if args.print_info {
let fmt = args.format.unwrap_or("#{pane_id}");
Expand All @@ -708,36 +722,37 @@ fn handle_new_window(args: NewWindowArgs<'_>) -> Result<i32, ShimError> {
debug!(event = "shim.new_window_started", name = ?args.name);

let sid = session_id()?;
let mut registry = state::load(&sid)?;
let mut locked = state::load_and_lock(&sid)?;

let window_name = args
.name
.map(|s| s.to_string())
.unwrap_or_else(|| "window".to_string());
let window_id = format!("{}", registry.windows.len());

registry.windows.insert(
// Read phase: derive IDs from current state
let window_id = format!("{}", locked.registry().windows.len());
let session_key = args
.target
.and_then(|t| t.split(':').next())
.unwrap_or(&locked.registry().session_name)
.to_string();

// Write phase: mutate registry
locked.registry_mut().windows.insert(
window_id.clone(),
WindowEntry {
name: window_name.clone(),
pane_ids: vec![],
},
);

let pane_id = create_pty_pane(&mut registry, &window_id, &[])?;

// Add window to the target session (or default session)
let session_key = args
.target
.and_then(|t| t.split(':').next())
.unwrap_or(&registry.session_name)
.to_string();
let pane_id = create_pty_pane(locked.registry_mut(), &window_id, &[])?;

if let Some(session) = registry.sessions.get_mut(&session_key) {
if let Some(session) = locked.registry_mut().sessions.get_mut(&session_key) {
session.windows.push(window_id.clone());
}

state::save(&sid, &registry)?;
locked.save()?;

if args.print_info {
let fmt = args.format.unwrap_or("#{pane_id}");
Expand Down Expand Up @@ -789,13 +804,13 @@ fn handle_break_pane(args: BreakPaneArgs<'_>) -> Result<i32, ShimError> {
debug!(event = "shim.break_pane_started", source = ?args.source);

let sid = session_id()?;
let mut registry = state::load(&sid)?;
let mut locked = state::load_and_lock(&sid)?;

let pane_id = resolve_pane_id(args.source);
if let Some(pane) = registry.panes.get_mut(&pane_id) {
if let Some(pane) = locked.registry_mut().panes.get_mut(&pane_id) {
pane.hidden = true;
}
state::save(&sid, &registry)?;
locked.save()?;

debug!(event = "shim.break_pane_completed", pane_id = pane_id);
Ok(0)
Expand All @@ -805,13 +820,13 @@ fn handle_join_pane(args: JoinPaneArgs<'_>) -> Result<i32, ShimError> {
debug!(event = "shim.join_pane_started", source = ?args.source);

let sid = session_id()?;
let mut registry = state::load(&sid)?;
let mut locked = state::load_and_lock(&sid)?;

let pane_id = resolve_pane_id(args.source);
if let Some(pane) = registry.panes.get_mut(&pane_id) {
if let Some(pane) = locked.registry_mut().panes.get_mut(&pane_id) {
pane.hidden = false;
}
state::save(&sid, &registry)?;
locked.save()?;

debug!(event = "shim.join_pane_completed", pane_id = pane_id);
Ok(0)
Expand Down
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