Warm sidebar thread detail subscriptions

[juliusmarminge]

Summary

• Prewarm thread detail subscriptions for the first visible sidebar threads so nearby navigation can reuse hot data.
• Extend the thread-detail cache policy to keep non-idle threads sticky and only evict idle subscriptions.
• Increase the idle TTL and cache capacity to reduce churn while navigating and working in active threads.
• Add tests for sidebar prewarm selection and the updated subscription eviction behavior.

Testing

• bun fmt
• bun lint
• bun typecheck
• bun run test apps/web/src/components/Sidebar.logic.test.ts
• bun run test apps/web/src/environments/runtime/service.threadSubscriptions.test.ts

---

Note

Medium Risk
Changes thread-detail subscription caching/eviction and adds background prewarming from the sidebar, which can affect memory/network usage and when subscriptions are released. Logic now depends on thread activity state to prevent eviction, so regressions could keep subscriptions alive longer than intended.

Overview
Prewarms thread-detail data for the first visible sidebar threads by retaining their detail subscriptions (default 10) while they remain visible, releasing them when the visible set changes.

Updates the runtime thread-detail subscription cache policy to be stickier for non-idle threads (pending approvals/input/plan, running turns, or non-idle orchestration), and to evict only idle unretained entries; idle TTL increases to 15 minutes and cache capacity to 32.

Adds unit tests covering getSidebarThreadIdsToPrewarm and the new eviction behavior (longer warm period, non-idle stickiness, and increased capacity before eviction).

^{Reviewed by Cursor Bugbot for commit a4afe8c. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Warm thread detail subscriptions for visible sidebar threads

• The sidebar now retains thread detail subscriptions for up to 10 visible threads (SIDEBAR_THREAD_PREWARM_LIMIT) using retainThreadDetailSubscription, releasing them when threads leave the prewarmed set.
• The thread detail subscription cache is expanded from 8 to 32 entries and the idle eviction timeout is increased from 2 to 15 minutes.
• Non-idle threads (pending approvals, running turns, etc.) are exempt from eviction via a new isNonIdleThreadDetailSubscription helper in service.ts; eviction is deferred until the thread becomes idle.
• Eviction schedules are reconciled after shell snapshot syncs, recovered event batches, and shell upserts to keep cache state consistent.
• Behavioral Change: releasing a subscription no longer always schedules eviction — non-idle threads remain cached until idle, and capacity eviction only removes the least-recently-accessed idle entries.

^{Macroscope summarized a4afe8c.}

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 65d2f790-b9a8-4a72-937c-a2601d27dbcc

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch t3code/thread-subscription-cache-policy

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

Bugbot Autofix prepared a fix for the issue found in the latest run.

• ✅ Fixed: Prewarm effect re-runs on every sidebar thread change
  • Replaced the prewarmedSidebarThreads memo (which depended on the frequently-changing sidebarThreadByKey map) with prewarmedSidebarThreadRefs that uses parseScopedThreadKey to extract stable identity pairs directly from prewarmedSidebarThreadKeys, breaking the dependency chain that caused unnecessary effect re-runs on every thread summary update.

Or push these changes by commenting:

@cursor push 1017cc1156

Preview (1017cc1156)

diff --git a/apps/web/src/components/Sidebar.tsx b/apps/web/src/components/Sidebar.tsx
--- a/apps/web/src/components/Sidebar.tsx
+++ b/apps/web/src/components/Sidebar.tsx
@@ -43,6 +43,7 @@
   type GitStatusResult,
 } from "@t3tools/contracts";
 import {
+  parseScopedThreadKey,
   scopedProjectKey,
   scopedThreadKey,
   scopeProjectRef,
@@ -2884,18 +2885,18 @@
     () => getSidebarThreadIdsToPrewarm(visibleSidebarThreadKeys),
     [visibleSidebarThreadKeys],
   );
-  const prewarmedSidebarThreads = useMemo(
+  const prewarmedSidebarThreadRefs = useMemo(
     () =>
       prewarmedSidebarThreadKeys.flatMap((threadKey) => {
-        const thread = sidebarThreadByKey.get(threadKey);
-        return thread ? [thread] : [];
+        const ref = parseScopedThreadKey(threadKey);
+        return ref ? [ref] : [];
       }),
-    [prewarmedSidebarThreadKeys, sidebarThreadByKey],
+    [prewarmedSidebarThreadKeys],
   );
 
   useEffect(() => {
-    const releases = prewarmedSidebarThreads.map((thread) =>
-      retainThreadDetailSubscription(thread.environmentId, thread.id),
+    const releases = prewarmedSidebarThreadRefs.map((ref) =>
+      retainThreadDetailSubscription(ref.environmentId, ref.threadId),
     );
 
     return () => {
@@ -2903,7 +2904,7 @@
         release();
       }
     };
-  }, [prewarmedSidebarThreads]);
+  }, [prewarmedSidebarThreadRefs]);
 
   useEffect(() => {
     const clearThreadJumpHints = () => {

_{You can send follow-ups to the cloud agent here.}

^{Reviewed by Cursor Bugbot for commit 9284b86. Configure here.}

[macroscopeapp]

Approvability

Verdict: Needs human review

This PR introduces a new feature that proactively warms thread subscriptions for visible sidebar items and significantly changes the subscription cache policy (longer TTL, larger cache, sticky non-idle threads). While the author owns this code and changes are well-tested, this is a new capability with runtime behavior implications around network subscriptions and resource management that warrants human review.

^{You can customize Macroscope's approvability policy. Learn more.}

[juliusmarminge]

@cursor push 1017cc1