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perf(server): stop remapping every thread on each thread event #13720

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Merged
t3dotgg merged 2 commits into from
Sep 26, 2026
+22 −6
Merged

perf(server): stop remapping every thread on each thread event #13720

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a9b335c
perf(server): stop remapping every thread on each thread event
claude Sep 25, 2026
b68cc2a
perf(server): scan threads once for message and activity events
claude Sep 25, 2026
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28 changes: 22 additions & 6 deletions apps/server/src/orchestration/projector.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -117,12 +117,26 @@ function settledTurnStateForSessionStatus(
}
}

// Runs for every thread event (including streaming deltas) against every
// thread the server has ever seen, so copy the array rather than map it.
function updateThread(
threads: ReadonlyArray<OrchestrationThread>,
threadId: ThreadId,
patch: ThreadPatch,
): OrchestrationThread[] {
return threads.map((thread) => (thread.id === threadId ? { ...thread, ...patch } : thread));
): ReadonlyArray<OrchestrationThread> {
const index = threads.findIndex((thread) => thread.id === threadId);
return index === -1 ? threads : patchThreadAt(threads, index, patch);
}

/** For callers that already located the thread and must not scan again. */
function patchThreadAt(
threads: ReadonlyArray<OrchestrationThread>,
index: number,
patch: ThreadPatch,
): ReadonlyArray<OrchestrationThread> {
const next = threads.slice();
next[index] = { ...threads[index]!, ...patch };
return next;
}

/** Patch that swaps a thread's links and re-derives the legacy single-PR field from them. */
Expand Down Expand Up @@ -767,7 +781,8 @@ export function projectEvent(
event.type,
"payload",
);
const thread = nextBase.threads.find((entry) => entry.id === payload.threadId);
const threadIndex = nextBase.threads.findIndex((entry) => entry.id === payload.threadId);
const thread = nextBase.threads[threadIndex];
if (!thread) {
return nextBase;
}
Expand Down Expand Up @@ -815,7 +830,7 @@ export function projectEvent(

return {
...nextBase,
threads: updateThread(nextBase.threads, payload.threadId, {
threads: patchThreadAt(nextBase.threads, threadIndex, {
messages: cappedMessages,
updatedAt: event.occurredAt,
}),
Expand Down Expand Up @@ -1055,7 +1070,8 @@ export function projectEvent(
"payload",
).pipe(
Effect.map((payload) => {
const thread = nextBase.threads.find((entry) => entry.id === payload.threadId);
const threadIndex = nextBase.threads.findIndex((entry) => entry.id === payload.threadId);
const thread = nextBase.threads[threadIndex];
if (!thread) {
return nextBase;
}
Expand All @@ -1069,7 +1085,7 @@ export function projectEvent(

return {
...nextBase,
threads: updateThread(nextBase.threads, payload.threadId, {
threads: patchThreadAt(nextBase.threads, threadIndex, {
activities,
updatedAt: event.occurredAt,
}),
Expand Down
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