From a27d529fa7b0c9846e046c47bb5a5eee1f9dc663 Mon Sep 17 00:00:00 2001
From: "J. Champagne" <jchampagne@maplegoosestudio.ca>
Date: Sat, 14 Mar 2026 11:47:27 -0400
Subject: [PATCH] feat(frontend): Add generations counter to inform frontends
 when a list should be re-rendered.

---
 crates/pikl-core/src/model/event.rs |  4 ++++
 crates/pikl-tui/src/lib.rs          | 12 +++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/crates/pikl-core/src/model/event.rs b/crates/pikl-core/src/model/event.rs
index 3fcf2c2..4028945 100644
--- a/crates/pikl-core/src/model/event.rs
+++ b/crates/pikl-core/src/model/event.rs
@@ -72,6 +72,10 @@ pub struct ViewState {
     pub total_items: usize,
     pub total_filtered: usize,
     pub mode: Mode,
+    /// Monotonically increasing counter. Each call to
+    /// `build_view_state()` bumps this, so frontends can
+    /// detect duplicate broadcasts and skip redundant redraws.
+    pub generation: u64,
 }
 
 /// A single item in the current viewport window. Has the
diff --git a/crates/pikl-tui/src/lib.rs b/crates/pikl-tui/src/lib.rs
index 8c2fe8b..9c17f96 100644
--- a/crates/pikl-tui/src/lib.rs
+++ b/crates/pikl-tui/src/lib.rs
@@ -82,6 +82,7 @@ async fn run_inner(
     let mut event_stream = EventStream::new();
     let mut mode = Mode::Insert;
     let mut pending = PendingKey::None;
+    let mut last_generation: u64 = 0;
 
     loop {
         if let Some(ref vs) = view_state {
@@ -118,6 +119,11 @@ async fn run_inner(
             menu_event = event_rx.recv() => {
                 match menu_event {
                     Ok(MenuEvent::StateChanged(vs)) => {
+                        // Skip duplicate broadcasts
+                        if vs.generation == last_generation {
+                            continue;
+                        }
+                        last_generation = vs.generation;
                         // Sync filter text from core. Local keystrokes
                         // update filter_text immediately for responsiveness,
                         // but if core pushes a different value (e.g. IPC
@@ -135,7 +141,9 @@ async fn run_inner(
                     Ok(MenuEvent::Selected(_) | MenuEvent::Quicklist(_) | MenuEvent::Cancelled) => {
                         break;
                     }
-                    Err(broadcast::error::RecvError::Lagged(_)) => {}
+                    Err(broadcast::error::RecvError::Lagged(n)) => {
+                        tracing::warn!(skipped = n, "TUI fell behind on state broadcasts");
+                    }
                     Err(broadcast::error::RecvError::Closed) => {
                         break;
                     }
@@ -340,6 +348,7 @@ mod tests {
             total_items: 5,
             total_filtered: 3,
             mode: Mode::Insert,
+            generation: 1,
         }
     }
 
@@ -811,6 +820,7 @@ mod tests {
             total_items: 0,
             total_filtered: 0,
             mode: Mode::Insert,
+            generation: 1,
         };
         let backend = render_to_backend(30, 4, &vs, "");
         let prompt = line_text(&backend, 0);