Introducing Replay:
Solana mainnet, paused on a frame you can drive.

POST /boot with the snapshot you picked from the catalog. Returns 202 immediately; uncached boots walk through downloading → extracting → indexing → ready; cached boots skip the network fetch and still decompress locally before indexing. Integrity is checked on the way in — anything off, the environment stays dead and tells you what failed.

A fresh boot resets the local fork — every advance and mutation since the last boot is dropped. That's the only knob that clears mutation.dirty, and it's deliberate: rebooting is cheap, so the operational story is "boot a clean canonical mainnet, do your work, throw it away."

The Accounts tab is your production address book. Quick-add chips for the programs you always reach for; a paste input for the ones you don't. The detail panel reads the bank: owner, balance, data size, rent epoch, raw bytes.

POST /accounts/patchwrites one or more accounts straight into the local fork. Merge (keep the fields you don't set) or replace (overwrite the whole account). The moment a patch lands, mutation.dirty=trueand the UI flips a label to remind you you're on a labeled local fork. Reboot to return to canonical mainnet.

POST /advance walks the fork forward to a target slot, optionally splicing your transactions into specific slots along the way. Replay replays canonical mainnet blocks and weaves your transactions in where you ask — eight anchors, one queue: block_start, block_end, before_index, after_index, before_signature, after_signature, replace_index, at_index_clamped.

It walks forward block by block — canonical, then yours, then canonical again — in exactly the order the bank applies them. getBlock over JSON-RPC returns the assembled block, with your splice at the index you put it. You can cancel any advance mid-flight; blocks already rooted stay applied. There is no rollback.

The Blocks tab is the canonical block explorer for the chain you just built. Walk forward from your boot point. Click any row for decoded instructions, log messages, pre/post balances. Filter by signature or any pubkey in the tx.

The list reflects your replay chain, not upstream mainnet, so the transaction you spliced in at slot 418,908,420 sits exactly where you put it. 1,446 canonical txs in a block, your splice at index 10, the fee at 1,005,000 lamports — visible, decoded, indexable.

There is nothing to rewrite. Your environment speaks the standard Solana JSON-RPC surface, WebSocket PubSub, and — if you booted with streaming on — gRPC. @solana/web3.js, anchor, solana-cli, your indexer, your bots, your dashboards — reveal the direct endpoint when you need it, copy it, and treat that URL like an operational secret.

Block height does not advance unless you call /advance, so anything that loops on onSlotChangeblocks until you ask it to. That's the contract — and the LLM operator quickstart spells it out so agents don't write busy-waits.

Start slot, target slot, duration, status. Twenty most recent jobs, in memory. Expand a row for the exit code, the finality choice, and the full job ID. The signal you want when you're iterating on a splice plan and need to know which run produced which state.

The same audit log carries every patch, splice, and program deploy — GET /accounts/patch/history returns up to 2,000 records (newest first), spanning every mutation kind, with the before/after state hashes for each. Pipe it to jq if you want the diff.