feat(ui): sort sessions by recent activity

[officialasishkumar]

Summary

• Sort session lists by updated_at descending so active long-running chats stay visible
• Touch session activity when events or tasks are stored
• Group and display sidebar sessions by last activity, with story coverage for older sessions updated today

Fixes #1556

Testing

• go test ./core/internal/database -run 'TestListSessionsOrdersByRecentActivity|TestStoreEventTouchesSessionActivity|TestStoreTaskTouchesSessionActivity' -count=1\n- npm run lint -- --quiet

[jsonmp-k8]

Good feature — sorting by activity is the right UX. A few issues to address:

1. StoreTask uses TouchSession (no user_id check) while StoreEvents uses TouchSessionForUser (with user_id check)

TouchSession updates any session matching the ID regardless of who owns it. TouchSessionForUser scopes to the user. Since protocol.Task doesn't carry a user_id, using TouchSession is understandable, but it means any task upsert can bump another user's session timestamp. Consider whether this matters for multi-tenant scenarios, or add a comment explaining the choice.

2. Fake client StoreTask touch logic iterates all sessions

for _, session := range c.sessions {
    if session.ID == task.ContextID {
        session.UpdatedAt = now
    }
}

This scans every session to find one by ID. The sessions map is keyed by sessionKey(id, userID), so you can't do a direct lookup without the user_id. This is fine for a fake/test client, but worth noting — a break after the match would be cleaner since session IDs are unique.

3. sortSessionsByActivity can use cmp.Compare instead of manual if-chains

The time.Time.Compare method returns -1/0/1 directly. You can simplify:

func sortSessionsByActivity(sessions []database.Session) {
    slices.SortStableFunc(sessions, func(i, j database.Session) int {
        if c := j.UpdatedAt.Compare(i.UpdatedAt); c != 0 {
            return c
        }
        if c := j.CreatedAt.Compare(i.CreatedAt); c != 0 {
            return c
        }
        return strings.Compare(i.ID, j.ID)
    })
}

Note the j before i to get descending order.

4. UI: createdAt prop name is now misleading

In SessionGroup.tsx, the createdAt prop now receives session.updated_at || session.created_at. The prop name createdAt no longer reflects what it contains. Consider renaming it to lastActivity or activityAt to avoid confusion for future readers.

Overall the backend changes (SQL, transaction wrapping, tests) look solid. The test coverage is thorough.

[jsonmp-k8]

.

[officialasishkumar]

Addressed the review feedback in fe08838: added the task touch comment, broke the fake-client loop on match, simplified the sort comparator, and renamed the UI timestamp prop to activityAt.

[EItanya]

This feels ugly, maybe the InsertEvent query should also touch the session automatically?

[officialasishkumar]

Moved the session activity update into the InsertEvent SQL path in 4699816.

[EItanya]

Same comment here

[officialasishkumar]

Handled the same way for task upserts in 4699816 by updating the session in the SQL CTE.

[EItanya]

Hey there @officialasishkumar I deleted the fake db client in a recent PR, please resolve the conflicts and then I will merge

[officialasishkumar]

Rebased on current main and resolved the conflict by keeping the upstream fake-client deletion. go test ./core/internal/database passes from the go/ directory.

[Copilot]

Pull request overview

Implements “recent activity” session ordering across the backend and UI so long-running active chats stay visible, aligning with the requested behavior in #1556.

Changes:

• Update session list queries to sort by updated_at (desc) with created_at as a tie-breaker.
• Touch session.updated_at when storing events or tasks.
• Update sidebar grouping/sorting and timestamps to use last activity time (updated_at fallback to created_at), with Storybook coverage for an older-but-recently-active session.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
ui/src/components/sidebars/SessionGroup.tsx	Passes last-activity timestamp to each chat row.
ui/src/components/sidebars/GroupedChats.tsx	Groups/sorts sessions by last activity date.
ui/src/components/sidebars/GroupedChats.stories.tsx	Adds story covering an older session updated today.
ui/src/components/sidebars/ChatItem.tsx	Renames timestamp prop to activityAt and displays it.
ui/src/components/sidebars/ChatItem.stories.tsx	Updates stories to use activityAt.
go/core/internal/database/queries/tasks.sql	Touches session updated_at on task upsert.
go/core/internal/database/queries/sessions.sql	Orders session lists by updated_at desc.
go/core/internal/database/queries/events.sql	Touches session updated_at on event insert.
go/core/internal/database/gen/tasks.sql.go	Regenerates sqlc output for updated task query.
go/core/internal/database/gen/sessions.sql.go	Regenerates sqlc output for updated session list ordering.
go/core/internal/database/gen/events.sql.go	Regenerates sqlc output for updated event insert query.
go/core/internal/database/client_test.go	Adds DB tests for ordering + activity touch behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

getActivityDate() allocates a new Date each time it’s called, and the sort comparator calls it repeatedly (O(n log n)). Consider computing a numeric activity timestamp once per session (e.g., Date.parse(updated_at ?? created_at)) and sorting on that to reduce allocations and repeated parsing.

[officialasishkumar]

Fixed in b7a3418 by computing one numeric activity timestamp per session and sorting on that cached value.

[Copilot]

This UPDATE always runs even when the inserted event has a NULL session_id (common when StoreEvents passes an empty session). Adding a inserted_event.session_id IS NOT NULL predicate (or guarding in the CTE) would avoid doing an unnecessary UPDATE step.

Suggested change

	WHERE session.id = inserted_event.session_id
	WHERE inserted_event.session_id IS NOT NULL
	AND session.id = inserted_event.session_id

[officialasishkumar]

Fixed in b7a3418 by adding the inserted_event.session_id IS NOT NULL guard before touching the session.

[Copilot]

Similar to events, this UPDATE step will still be planned/executed even if the upserted task’s session_id is NULL. Consider adding upserted_task.session_id IS NOT NULL to the UPDATE’s WHERE clause to skip the session touch work when there’s no session associated.

Suggested change

	WHERE session.id = upserted_task.session_id
	WHERE upserted_task.session_id IS NOT NULL
	AND session.id = upserted_task.session_id

[officialasishkumar]

Fixed in b7a3418 by adding the upserted_task.session_id IS NOT NULL guard before touching the session.

[EItanya]

In general tests like this shouldn't execute raw SQL. Rather we should use the new queries to prove the actual behavior