[Drift] Kotlin SDK adds opt-in support for the new checkpoint-request protocol (powersync-kotlin #371)

[benitav]

What's changing: The Kotlin SDK adds opt-in, experimental support for the new checkpoint-request protocol. Setting SyncOptions.checkpointMode to CheckpointMode.Requests() switches the sync client to request-based checkpoint reconciliation, and a new CustomCheckpointRequestConnector abstract class (with postCheckpointRequest()) lets backends that process uploads asynchronously participate. Both are gated behind @ExperimentalCheckpointRequestsApi. This PR does not add a client-facing requestCheckpoint()/waitForSync() API to the Kotlin SDK itself, only the protocol-level plumbing.

High priority — existing docs are now inaccurate or incomplete
None identified.

For reviewer consideration — worth documenting

• Kotlin SDK support for the checkpoint-request protocol. Sync Catch-Up (Checkpoint Requests) (client-sdks/advanced/checkpoint-requests.mdx → https://docs.powersync.com/client-sdks/advanced/checkpoint-requests) currently opens with a Warning stating "Client support is currently available for Swift and requires PowerSync Service version 1.24.0 or later. Support for the JavaScript SDKs is in progress, and other SDKs will follow." Kotlin now has protocol-level (experimental) support that the page doesn't mention. The page's "Prerequisites" and "Swift Connector" sections are Swift-specific; a "Kotlin Connector" section documenting CustomCheckpointRequestConnector.postCheckpointRequest() and setting checkpointMode = CheckpointMode.Requests() would be the Kotlin analog, once the feature is considered stable enough to document (it remains experimental as of this PR).

Related: #569 covers the JS SDK's adoption of the same protocol groundwork (a different source PR, powersync-js#1072). This issue is the Kotlin SDK's rollout of that same underlying feature, not a duplicate.

Source PR: powersync-ja/powersync-kotlin#371. Merged 2026-08-21.

Filed automatically by Claude Code (claude-sonnet-5). A human must verify the scope, prepare the docs PR, and publish it only once this update has been released.

[benitav]

A follow-up PR also relates to this issue: powersync-kotlin#373 (merged 2026-08-24) adds the client-facing PowerSyncDatabase.requestCheckpoint() method and CheckpointRequest.waitForSync() to the Kotlin SDK, matching the existing Swift and JavaScript implementations. Where #371 (covered above) only added the protocol-level plumbing (SyncOptions.checkpointMode, CustomCheckpointRequestConnector), this PR is the client-facing API itself — the same gap this issue already flagged in client-sdks/advanced/checkpoint-requests.mdx's Warning callout ("Client support is currently available for Swift... other SDKs will follow") and in handling-writes/custom-write-checkpoints.mdx's "Client support is currently available for Swift" note. Both statements are now further out of date since Kotlin has a usable (if still @ExperimentalCheckpointRequestsApi-gated) requestCheckpoint()/waitForSync() surface, not just protocol groundwork. No additional pages are affected beyond what's already listed here.

Filed automatically by Claude Code (claude-sonnet-5). A human must verify the scope, prepare the docs PR, and publish it only once this update has been released.

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Generated by Claude Code

[benitav]

powersync-kotlin#373 also relates to this issue. Merged 2026-08-24, it adds the client-facing PowerSyncDatabase.requestCheckpoint() method and a CheckpointRequest type to the Kotlin SDK, matching the existing Swift and JavaScript implementations. This is the follow-up this issue anticipated: #371 only added the experimental protocol-level plumbing (CheckpointMode.Requests(), CustomCheckpointRequestConnector), and #373 is what actually exposes requestCheckpoint()/waiting-for-sync to Kotlin app developers. The client-sdks/advanced/checkpoint-requests.mdx page's opening Warning ("Client support is currently available for Swift... other SDKs will follow") is now out of date for Kotlin on both fronts, and the page's Swift-only "Prerequisites" and "Swift Connector" sections would need Kotlin equivalents once this is considered stable enough to document (per #373's PR description, no experimental gating was mentioned, so it may already be closer to stable than #371's plumbing was).

Filed automatically by Claude Code (claude-sonnet-5). A human must verify the scope, prepare the docs PR, and publish it only once this update has been released.

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Generated by Claude Code