[anhthii]

Summary

• from_latest is now a *bool that defaults to true when unset in both defaults and the chain config. A per-chain value overrides defaults.
• On a cold start (no checkpoint in the block store), a chain with from_latest: false begins at its configured start_block instead of the chain head. Previously start_block was ignored entirely.
• Config validation rejects from_latest: false without a start_block (> 0), rather than silently falling back to the chain head.
• Warm restarts are unchanged: they resume from the persisted checkpoint and queue catchup regardless of start_block.

defaults:
  from_latest: true
chains:
  ethereum_sepolia:
    from_latest: false
    start_block: 11869752   # cold start begins here

Notes

• If start_block is more than max_lag (default 100) behind head, the regular worker skips ahead and queues the gap for the catchup worker, which needs --catchup enabled.

Test plan

• go test ./pkg/common/config/ ./internal/worker/
• New tests: cold start from start_block, from_latest ignores start_block, warm restart ignores start_block, defaults inheritance, validation