From 0e4525aa1fe29ded56362e9c5b955651ca65a5d4 Mon Sep 17 00:00:00 2001
From: Fredrik Ahlgren <fredrik@sourceful-labs.com>
Date: Mon, 12 Oct 2026 20:24:06 +0200
Subject: [PATCH] fix(web): keep live markers off old history segments

Signed-off-by: Fredrik Ahlgren <fredrik@sourceful-labs.com>
---
 .changeset/live-history-gap-tip.md |  5 +++++
 web/app.js                         |  6 +++---
 web/history-quality.test.mjs       | 22 ++++++++++++++++++++++
 3 files changed, 30 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/live-history-gap-tip.md

diff --git a/.changeset/live-history-gap-tip.md b/.changeset/live-history-gap-tip.md
new file mode 100644
index 000000000..3911eb18b
--- /dev/null
+++ b/.changeset/live-history-gap-tip.md
@@ -0,0 +1,5 @@
+---
+"ftw": patch
+---
+
+Pulse only the latest known sample in the Live chart. Earlier points before a missing measurement stay still, and an unknown latest sample has no live marker.
diff --git a/web/app.js b/web/app.js
index b0fb9ed64..40ae1a193 100644
--- a/web/app.js
+++ b/web/app.js
@@ -1349,11 +1349,11 @@
       ctx.stroke();
       ctx.setLineDash([]);
 
-      // Cache the right-most point for un-clipped pulse drawing
-      if (sr.width >= 2) {
+      });
+      // Only the current sample may pulse. Earlier segments remain still.
+      if (sr.width >= 2 && pts.length && sr.data.length === chartHistory.timestamps.length) {
         liveTips.push({ x: pts[pts.length - 1].x, y: pts[pts.length - 1].y, color: sr.color });
       }
-      });
     });
 
     // ---- Forward-looking forecast (dashed lines from plan) ----
diff --git a/web/history-quality.test.mjs b/web/history-quality.test.mjs
index 67b8776a4..fd874f660 100644
--- a/web/history-quality.test.mjs
+++ b/web/history-quality.test.mjs
@@ -31,3 +31,25 @@ test('daily view renders unknown home use and a measured grid total',()=>{
  assert.match(els['energy-history-insight'].innerHTML,/Incomplete measurements/);
  assert.doesNotMatch(els['energy-history-insight'].innerHTML,/%/);
 });
+
+function liveTipsFor(data, timestamps=data.map((_,i)=>i)) {
+ const noop=()=>{};
+ const ctx={createLinearGradient:()=>({addColorStop:noop}),beginPath:noop,moveTo:noop,lineTo:noop,closePath:noop,fill:noop,stroke:noop,setLineDash:noop};
+ const c={ctx,series:[{data,color:'#ef4444',width:2}],chartHistory:{timestamps},tsToX:x=>x,valToY:y=>y,pad:{top:0},plotH:100,hexAlpha:()=>''};
+ vm.createContext(c);
+ const start=app.indexOf('    var liveTips = [];');
+ const end=app.indexOf('    // ---- Forward-looking forecast',start);
+ assert.ok(start>=0 && end>start);
+ vm.runInContext(app.slice(start,end),c);
+ return Array.from(c.liveTips,tip=>({x:tip.x,y:tip.y}));
+}
+
+test('live chart pulses only the current segment after a measurement gap',()=>{
+ assert.deepEqual(liveTipsFor([100,200,null,300,400]),[{x:4,y:400}]);
+ assert.deepEqual(liveTipsFor([100,200,null,300]),[{x:3,y:300}]);
+});
+
+test('live chart leaves old endpoints quiet when the latest measurement is unknown',()=>{
+ assert.deepEqual(liveTipsFor([100,200,null,300,400,null]),[]);
+ assert.deepEqual(liveTipsFor([100,200],[0,1,2]),[]);
+});