Durable connectors: resumable pagination, incremental sync, and pausable backfill

[mcclowes]

Phase 3 · Differentiate on the domain

Make API integration mechanics resumable primitives, not things users hand-roll. This is the differentiation Temporal doesn't ship: durable, API-native connectors.

Goals

• Resumable pagination: a multi-page fetch that survives a restart and continues from the last persisted page (built on the event log), with per-page flush so memory stays flat (ties into Pagination: unbounded memory, off-by-one hasMore, cursor infinite loop, dropped final page #128).
• Incremental sync as a first-class, log-backed primitive (correct checkpoint ordering from Incremental sync checkpoint advances before data is stored, silently dropping records #119).
• Backfill mode: a large historical sync you can pause, resume, and that survives a deploy. Flagship demo: pause a 10M-row backfill, redeploy, resume cleanly.

Why

This is the "killer demo" that sells durable + API-native together.

Part of the durable-execution roadmap (see the epic).

[mcclowes]

Shipped resumable, durable connectors in #194: a paginated fetch marked backfill: true persists per-page progress (page.completed) to the execution log, resumes from the last page on restart (no re-fetch), and stays memory-bounded per run via backfillMaxItemsPerRun — so an arbitrarily large historical sync completes across many bounded runs and survives a deploy. Cursor and offset resume both covered by tests; incremental sync is log-backed via #191.