From 50734e5117dd1d84ced4c8f7a0dfd689e3b0caa7 Mon Sep 17 00:00:00 2001
From: Lyon <88232613+pikasTech@users.noreply.github.com>
Date: Wed, 24 Jun 2026 13:08:27 +0800
Subject: [PATCH] fix(workbench): keep projected turn start time stable (#2039)

---
 internal/cloud/workbench-projection-writer.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/internal/cloud/workbench-projection-writer.ts b/internal/cloud/workbench-projection-writer.ts
index f5c209d1..00177896 100644
--- a/internal/cloud/workbench-projection-writer.ts
+++ b/internal/cloud/workbench-projection-writer.ts
@@ -111,7 +111,11 @@ export async function writeWorkbenchProjectionEvent({ runtimeStore = null, event
   const previousTerminal = checkpointIsTerminal(previousCheckpoint);
   const suppressedAfterSeal = previousTerminal && !terminal;
   const explicitStartedAt = optionalTimestampValue(event.startedAt ?? event.traceStartedAt ?? event.runnerStartedAt);
-  const startedAt = explicitStartedAt ?? previousTiming?.startedAt ?? (sourceSeq <= 1 ? occurredAt : null);
+  // Once a trace has a durable checkpoint, startedAt is sealed as the card
+  // elapsed-time source. Later trace/result hydration can carry older or newer
+  // startedAt values, but it must not make the visible Code Agent card jump by
+  // switching to a different clock origin.
+  const startedAt = previousTiming?.startedAt ?? explicitStartedAt ?? (sourceSeq <= 1 ? occurredAt : null);
   const lastEventAt = latestTimestamp(previousTiming?.lastEventAt, occurredAt);
   const finishedAt = terminal ? latestTimestamp(previousTiming?.lastEventAt, optionalTimestampValue(event.finishedAt), occurredAt) : null;
   const timing = eventTimingProjection({ startedAt, lastEventAt, finishedAt, terminal });