feat: localized unread count

[isekovanic]

CLA

• I have signed the Stream CLA (required).
• Code changes are tested

Description of the changes, What, Why and How?

Spec: https://stream-wiki.notion.site/Local-Unread-Count-specification-38b6a5d7f9f68073a5e1c73298fe0d71

Adds an optin, client side unread count for channels that have read events disabled (e.g. livestreams). Those channels normally don't track unread at all and so _countMessageAsUnread bails out whenever own_capabilities lacks read-events, so integrators have no "N new messages" affordance to show while scrolled up.

With the new isLocalUnreadCountEnabled client option (default false), the SDK maintains a purely local unread count for those channels. It increments on incoming messages and is reset via the new channel.markReadLocally() method, which dispatches a client only message.local_read event. That event reuses the exact message.read state logic in _handleChannelEvent (so read state updates stay in one place) but skips syncDeliveredCandidates(), so the count is never sent to the backend. hasReadEvents() centralizes the capability check.

When offline support is enabled, the local read/unread state is persisted for channels with disabled read-events so the count survives a cold start. The offline DB handles message.local_read (guarded so it can only affect channels with disabled read-events channels with the option on) and falls back gracefully when state.read[userId] is absent, since the server never sends a read for these channels.

Behavior is fully gated behind the flag, so default off means no change for existing integrations.

Changelog

• Add isLocalUnreadCountEnabled client option for a client side unread count on channels with disabled read-events (e.g. livestreams)
• Add Channel.markReadLocally() to reset the local unread count with no backend call
• Add Channel.hasReadEvents() helper
• Add client only message.local_read event
• Persist local unread state to the offline DB so it survives app restarts

[github-actions]

Size Change: +2.51 kB (+0.61%)

Total Size: 412 kB

📦 View Changed

Filename	Size	Change
dist/cjs/index.browser.js	137 kB	+832 B (+0.61%)
dist/cjs/index.node.js	138 kB	+836 B (+0.61%)
dist/esm/index.mjs	136 kB	+840 B (+0.62%)

_{compressed-size-action}

[stream-ci-bot]

🎉 This PR is included in version 9.50.0 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot 📦🚀