sl0p: double-click a tab to rename itHEADmain

Double-clicking a tab in the bar switches to it and drops into RenameTab mode,
matching the double-click-to-rename we added for panes in the sl0ppij zellij
fork. Enter commits, Esc cancels, exactly as the rename keybind does.

Widgets are held behind &self and cannot keep click state, so double-click
detection lives centrally in ModuleConfig::handle_mouse_action and is passed
to Widget::process_click as a flag.

THE TRAP, and the reason this is not a two-line change:
handle_mouse_action also runs for Mouse::Release. A single click therefore
arrives as LeftClick followed by Release at the SAME position. Counting
releases would make every single click register as a double click, and
resetting on release would mean a real double click never registers at all,
since the release falls between the two clicks. Only LeftClick participates;
Release neither counts nor resets.

A completed pair is consumed, so a triple click does not fire a second rename.

switch_tab_to() is called before switch_to_input_mode(), because RenameTab acts
on the ACTIVE tab - renaming without switching first would rename the wrong one.

Threshold is 400ms, the same one zellij uses for text-selection double clicks,
so the bar feels consistent with the panes.

Detection is extracted as register_click_for_double_click() so it can be tested
without constructing a ModuleConfig. Tests cover: a real double click, the
release-in-between regression, too-slow clicks, clicks at different positions,
and the triple-click case.

Upstream tests still pass: 25 total (20 upstream + 5 new).

Note: this repo's .cargo/config.toml targets wasm32-wasip1 and runs tests under
wasmtime, which is not installed here. Tests are run with
`cargo test --target x86_64-unknown-linux-gnu` instead.

10 files changed, 190 insertions, 13 deletions

diff --git a/src/config.rs b/src/config.rs
index 093d15e..473ced0 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -73,6 +73,15 @@ pub fn event_mask_from_widget_name(name: &str) -> u8 {
 
 #[derive(Default, Debug)]
 pub struct ModuleConfig {
+    /// Position and time of the last LEFT CLICK, for double-click detection.
+    ///
+    /// Only Mouse::LeftClick updates this. Mouse::Release must NOT, even though
+    /// handle_mouse_action also runs for it: a single click arrives as
+    /// LeftClick followed by Release at the same position, so counting releases
+    /// would make every single click look like a double click. Release is also
+    /// not allowed to RESET it, because it legitimately falls between the two
+    /// clicks of a real double click.
+    pub last_left_click: Option<(usize, chrono::DateTime<chrono::Local>)>,
     pub left_parts_config: String,
     pub left_parts: Vec<FormattedPart>,
     pub center_parts_config: String,
@@ -89,6 +98,42 @@ pub struct ModuleConfig {
     pub hide_on_overlength: bool,
 }
 
+
+/// 400ms, the same threshold zellij uses for text-selection double clicks, so
+/// the bar feels consistent with the panes.
+pub const DOUBLE_CLICK_MS: i64 = 400;
+
+/// Record a mouse event and report whether it completes a double click.
+///
+/// Only Mouse::LeftClick participates. handle_mouse_action also runs for
+/// Mouse::Release, and a single click arrives as LeftClick then Release at the
+/// same position - counting releases would make every single click look like a
+/// double click. Release must not RESET the tracker either, since it falls
+/// between the two clicks of a real double click.
+pub fn register_click_for_double_click(
+    last_left_click: &mut Option<(usize, chrono::DateTime<chrono::Local>)>,
+    mouse: &Mouse,
+    click_pos: usize,
+    now: chrono::DateTime<chrono::Local>,
+) -> bool {
+    if !matches!(mouse, Mouse::LeftClick(..)) {
+        return false;
+    }
+    let is_double = last_left_click
+        .map(|(prev_pos, prev_time)| {
+            prev_pos == click_pos && (now - prev_time).num_milliseconds() <= DOUBLE_CLICK_MS
+        })
+        .unwrap_or(false);
+    // consume the pair, so a third click starts a new sequence rather than
+    // counting as another double
+    *last_left_click = if is_double {
+        None
+    } else {
+        Some((click_pos, now))
+    };
+    is_double
+}
+
 impl ModuleConfig {
     pub fn new(config: &BTreeMap<String, String>) -> anyhow::Result<Self> {
         let format_space_config = match config.get("format_space") {
@@ -168,6 +213,7 @@ impl ModuleConfig {
             border: border_config,
             format_precedence,
             hide_on_overlength,
+            last_left_click: None,
         })
     }
 
@@ -187,6 +233,13 @@ impl ModuleConfig {
             Mouse::Hover(_, _) => return,
         };
 
+        let is_double_click = register_click_for_double_click(
+            &mut self.last_left_click,
+            &mouse,
+            click_pos,
+            chrono::Local::now(),
+        );
+
         let output_left = self.left_parts.iter_mut().fold("".to_owned(), |acc, part| {
             format!(
                 "{}{}",
@@ -224,7 +277,7 @@ impl ModuleConfig {
 
         let mut offset = console::measure_text_width(&output_left);
 
-        self.process_widget_click(click_pos, &self.left_parts, &widget_map, &state, 0);
+        self.process_widget_click(click_pos, &self.left_parts, &widget_map, &state, 0, is_double_click);
 
         if click_pos <= offset {
             return;
@@ -244,6 +297,7 @@ impl ModuleConfig {
                 &widget_map,
                 &state,
                 offset,
+                is_double_click,
             );
 
             if click_pos <= offset {
@@ -263,7 +317,14 @@ impl ModuleConfig {
             ));
         }
 
-        self.process_widget_click(click_pos, &self.right_parts, &widget_map, &state, offset);
+        self.process_widget_click(
+            click_pos,
+            &self.right_parts,
+            &widget_map,
+            &state,
+            offset,
+            is_double_click,
+        );
     }
 
     fn process_widget_click(
@@ -273,6 +334,7 @@ impl ModuleConfig {
         widget_map: &BTreeMap<String, Arc<dyn Widget>>,
         state: &ZellijState,
         offset: usize,
+        is_double_click: bool,
     ) -> usize {
         let widget_string = widgets.iter().fold(String::new(), |a, b| a + &b.content);
 
@@ -320,7 +382,7 @@ impl ModuleConfig {
                 continue;
             }
 
-            wid.process_click(widget_key, state, click_pos - (pos + offset));
+            wid.process_click(widget_key, state, click_pos - (pos + offset), is_double_click);
         }
 
         console::measure_text_width(&rendered_output)
@@ -550,3 +612,107 @@ mod test {
         )
     }
 }
+
+#[cfg(test)]
+mod sl0p_double_click_tests {
+    use super::*;
+    use chrono::Duration;
+
+    fn t0() -> chrono::DateTime<chrono::Local> {
+        chrono::Local::now()
+    }
+
+    #[test]
+    fn two_quick_left_clicks_at_the_same_spot_are_a_double_click() {
+        let mut last = None;
+        let start = t0();
+        assert!(!register_click_for_double_click(
+            &mut last,
+            &Mouse::LeftClick(0, 12),
+            12,
+            start
+        ));
+        assert!(register_click_for_double_click(
+            &mut last,
+            &Mouse::LeftClick(0, 12),
+            12,
+            start + Duration::milliseconds(120)
+        ));
+    }
+
+    #[test]
+    fn the_release_between_two_clicks_is_ignored() {
+        // REGRESSION GUARD: handle_mouse_action runs for Release too. If Release
+        // were counted, a single click (LeftClick + Release) would register as a
+        // double click; if it reset the tracker, a real double click never would.
+        let mut last = None;
+        let start = t0();
+        register_click_for_double_click(&mut last, &Mouse::LeftClick(0, 12), 12, start);
+        assert!(
+            !register_click_for_double_click(
+                &mut last,
+                &Mouse::Release(0, 12),
+                12,
+                start + Duration::milliseconds(10)
+            ),
+            "a release must never count as a click"
+        );
+        assert!(
+            register_click_for_double_click(
+                &mut last,
+                &Mouse::LeftClick(0, 12),
+                12,
+                start + Duration::milliseconds(120)
+            ),
+            "the release must not have reset the sequence"
+        );
+    }
+
+    #[test]
+    fn slow_clicks_are_not_a_double_click() {
+        let mut last = None;
+        let start = t0();
+        register_click_for_double_click(&mut last, &Mouse::LeftClick(0, 12), 12, start);
+        assert!(!register_click_for_double_click(
+            &mut last,
+            &Mouse::LeftClick(0, 12),
+            12,
+            start + Duration::milliseconds(DOUBLE_CLICK_MS + 1)
+        ));
+    }
+
+    #[test]
+    fn clicks_at_different_positions_are_not_a_double_click() {
+        let mut last = None;
+        let start = t0();
+        register_click_for_double_click(&mut last, &Mouse::LeftClick(0, 12), 12, start);
+        assert!(!register_click_for_double_click(
+            &mut last,
+            &Mouse::LeftClick(0, 40),
+            40,
+            start + Duration::milliseconds(50)
+        ));
+    }
+
+    #[test]
+    fn a_triple_click_does_not_fire_a_second_rename() {
+        let mut last = None;
+        let start = t0();
+        register_click_for_double_click(&mut last, &Mouse::LeftClick(0, 12), 12, start);
+        assert!(register_click_for_double_click(
+            &mut last,
+            &Mouse::LeftClick(0, 12),
+            12,
+            start + Duration::milliseconds(100)
+        ));
+        assert!(
+            !register_click_for_double_click(
+                &mut last,
+                &Mouse::LeftClick(0, 12),
+                12,
+                start + Duration::milliseconds(200)
+            ),
+            "the pair is consumed, so a third click starts over"
+        );
+    }
+}
diff --git a/src/widgets/command.rs b/src/widgets/command.rs
index 245c5fc..55498c5 100644
--- a/src/widgets/command.rs
+++ b/src/widgets/command.rs
@@ -142,7 +142,7 @@ impl Widget for CommandWidget {
         }
     }
 
-    fn process_click(&self, name: &str, _state: &ZellijState, _pos: usize) {
+    fn process_click(&self, name: &str, _state: &ZellijState, _pos: usize, _is_double_click: bool) {
         let command_config = match self.config.get(name) {
             Some(cc) => cc,
             None => {
diff --git a/src/widgets/datetime.rs b/src/widgets/datetime.rs
index f500b5d..8e2a67e 100644
--- a/src/widgets/datetime.rs
+++ b/src/widgets/datetime.rs
@@ -105,5 +105,5 @@ impl Widget for DateTimeWidget {
             })
     }
 
-    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize) {}
+    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize, _is_double_click: bool) {}
 }
diff --git a/src/widgets/mode.rs b/src/widgets/mode.rs
index 8544cf9..f604291 100644
--- a/src/widgets/mode.rs
+++ b/src/widgets/mode.rs
@@ -139,7 +139,7 @@ impl Widget for ModeWidget {
             })
     }
 
-    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize) {}
+    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize, _is_double_click: bool) {}
 }
 
 impl ModeWidget {
diff --git a/src/widgets/notification.rs b/src/widgets/notification.rs
index 458d12a..b892d4a 100644
--- a/src/widgets/notification.rs
+++ b/src/widgets/notification.rs
@@ -74,5 +74,5 @@ impl Widget for NotificationWidget {
         output.to_owned()
     }
 
-    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize) {}
+    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize, _is_double_click: bool) {}
 }
diff --git a/src/widgets/pipe.rs b/src/widgets/pipe.rs
index 2c5f724..2c41378 100644
--- a/src/widgets/pipe.rs
+++ b/src/widgets/pipe.rs
@@ -85,7 +85,7 @@ impl Widget for PipeWidget {
         }
     }
 
-    fn process_click(&self, _name: &str, _state: &crate::config::ZellijState, _pos: usize) {}
+    fn process_click(&self, _name: &str, _state: &crate::config::ZellijState, _pos: usize, _is_double_click: bool) {}
 }
 
 fn render_dynamic_formatted_content(content: &str, config: &BTreeMap<String, String>) -> String {
diff --git a/src/widgets/session.rs b/src/widgets/session.rs
index 9e27f6d..107d5fa 100644
--- a/src/widgets/session.rs
+++ b/src/widgets/session.rs
@@ -18,5 +18,5 @@ impl Widget for SessionWidget {
         }
     }
 
-    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize) {}
+    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize, _is_double_click: bool) {}
 }
diff --git a/src/widgets/swap_layout.rs b/src/widgets/swap_layout.rs
index 8c9e036..ca58f97 100644
--- a/src/widgets/swap_layout.rs
+++ b/src/widgets/swap_layout.rs
@@ -66,7 +66,7 @@ impl Widget for SwapLayoutWidget {
         output
     }
 
-    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize) {
+    fn process_click(&self, _name: &str, _state: &ZellijState, _pos: usize, _is_double_click: bool) {
         next_swap_layout()
     }
 }
diff --git a/src/widgets/tabs.rs b/src/widgets/tabs.rs
index b62f581..970449a 100644
--- a/src/widgets/tabs.rs
+++ b/src/widgets/tabs.rs
@@ -2,7 +2,7 @@ use std::{cmp, collections::BTreeMap};
 
 use zellij_tile::{
     prelude::{InputMode, ModeInfo, PaneInfo, PaneManifest, TabInfo},
-    shim::switch_tab_to,
+    shim::{switch_tab_to, switch_to_input_mode},
 };
 
 use crate::{config::ZellijState, render::FormattedPart};
@@ -178,7 +178,7 @@ impl Widget for TabsWidget {
         output
     }
 
-    fn process_click(&self, _name: &str, state: &ZellijState, pos: usize) {
+    fn process_click(&self, _name: &str, state: &ZellijState, pos: usize, is_double_click: bool) {
         let mut offset = 0;
         let mut counter = 0;
 
@@ -226,6 +226,13 @@ impl Widget for TabsWidget {
             if pos > offset && pos < offset + content_len {
                 switch_tab_to(tab.position as u32 + 1);
 
+                if is_double_click {
+                    // RenameTab acts on the ACTIVE tab, so the switch above has
+                    // to happen first. Mirrors how the rename keybind works, so
+                    // Enter commits and Esc cancels exactly as usual.
+                    switch_to_input_mode(&InputMode::RenameTab);
+                }
+
                 break;
             }
 
diff --git a/src/widgets/widget.rs b/src/widgets/widget.rs
index 7087cba..4745713 100644
--- a/src/widgets/widget.rs
+++ b/src/widgets/widget.rs
@@ -2,5 +2,9 @@ use crate::config::ZellijState;
 
 pub trait Widget {
     fn process(&self, name: &str, state: &ZellijState) -> String;
-    fn process_click(&self, name: &str, state: &ZellijState, pos: usize);
+    /// `is_double_click` is true when this is the second click of a
+    /// double-click at the same position. Detected centrally in
+    /// ModuleConfig::handle_mouse_action, because widgets are held behind &self
+    /// and cannot keep click state of their own.
+    fn process_click(&self, name: &str, state: &ZellijState, pos: usize, is_double_click: bool);
 }