Squashed commit of the following:

commit 89c766a
Author: Willian Mitsuda <wmitsuda@gmail.com>
Date:   Fri Sep 8 03:03:47 2023 -0300

    First ots2 prototype

commit 674b77f
Author: ledgerwatch <akhounov@gmail.com>
Date:   Fri Jul 14 09:15:22 2023 +0100

    Bump patch version in stable to v2.48.1 (#7895)

    Co-authored-by: Alex Sharp <alexsharp@Alexs-MacBook-Pro-2.local>

commit 4c461ac
Author: Andrew Ashikhmin <34320705+yperbasis@users.noreply.github.com>
Date:   Fri Jul 14 09:15:15 2023 +0200

    Fix Gnosis sync from scratch (#7890)

    Fix an issue with historical block execution introduced by PR #7727

commit 084acc1
Author: Alex Sharp <akhounov@gmail.com>
Date:   Fri Jun 30 16:19:29 2023 +0100

    Stable modifications

README.md

@@ -1,3 +1,43 @@
+# Otterscan v2.0.0-alpha1 enabled Erigon
+
+This branch contains the experimental version of Erigon with Otterscan API **v2.0.0-alpha1**.
+
+Compatibility:
+
+- Erigon v2.48.1
+- Otterscan v2.0.0-alpha1
+
+## Warnings/disclaimers (READ THIS FIRST!!!)
+
+This is an experimental build. Make sure you are aware of the following first:
+
+- Don't use this build on production servers.
+- Make sure you backup your Erigon node before trying this build.
+- This version is made available in source-code form only.
+- DB model will change on next alphas. There will **NOT** be migration scripts. You'll need to restore your original Erigon node from a backup.
+- For now it is compatible with Erigon 2 only, but the end game is to support Erigon 3 only. At some point in the future we may change it.
+- Enabling Otterscan v2 support will produce extra data inside Erigon DB, so you'll need more disk space than a regular Erigon node.
+- At the first run of this patched build, extra stages will produce new indexes from genesis, so there will be extra sync time. Once it reaches the tip, the extra stages will take neglegible time per block iteration.
+- **Alphas were not optimized for space/time (yet). The goal here was to implement the spec for all token/contract indexing support and prove it was doable.**
+
+## How to use it
+
+### Erigon
+
+Build this branch as usual with `make` command.
+
+Add the `--experimental.ots2` CLI argument to the `erigon` command. That'll enable Otterscan V2 extra stages.
+
+Also enable the `ots2` API namespace, i.e., `--http.api "eth,erigon,ots,ots2"`.
+
+### Otterscan
+
+See: https://github.com/otterscan/otterscan/blob/develop/docs/ots2.md
+
+> The rest of this document contains the original Erigon README.
+
+---
+
 # Erigon
 
 Erigon is an implementation of Ethereum (execution layer with embeddable consensus layer), on the efficiency

cmd/erigon-el/stages/stages.go

@@ -0,0 +1,96 @@
+package stagedsync
+
+import (
+	"context"
+
+	proto_downloader "github.com/ledgerwatch/erigon-lib/gointerfaces/downloader"
+	"github.com/ledgerwatch/erigon-lib/kv"
+	"github.com/ledgerwatch/erigon-lib/state"
+	"github.com/ledgerwatch/log/v3"
+
+	"github.com/ledgerwatch/erigon/cmd/sentry/sentry"
+	"github.com/ledgerwatch/erigon/core/rawdb/blockio"
+	"github.com/ledgerwatch/erigon/core/vm"
+	"github.com/ledgerwatch/erigon/eth/ethconfig"
+	"github.com/ledgerwatch/erigon/eth/stagedsync"
+	"github.com/ledgerwatch/erigon/ethdb/prune"
+	"github.com/ledgerwatch/erigon/p2p"
+	"github.com/ledgerwatch/erigon/turbo/engineapi"
+	"github.com/ledgerwatch/erigon/turbo/services"
+	"github.com/ledgerwatch/erigon/turbo/shards"
+)
+
+func nullStage(firstCycle bool, badBlockUnwind bool, s *stagedsync.StageState, u stagedsync.Unwinder, tx kv.RwTx, logger log.Logger) error {
+	return nil
+}
+func ExecutionStages(ctx context.Context, sm prune.Mode, snapshots stagedsync.SnapshotsCfg, headers stagedsync.HeadersCfg, cumulativeIndex stagedsync.CumulativeIndexCfg, blockHashCfg stagedsync.BlockHashesCfg, bodies stagedsync.BodiesCfg, senders stagedsync.SendersCfg, exec stagedsync.ExecuteBlockCfg, hashState stagedsync.HashStateCfg, trieCfg stagedsync.TrieCfg, history stagedsync.HistoryCfg, logIndex stagedsync.LogIndexCfg, callTraces stagedsync.CallTracesCfg, txLookup stagedsync.TxLookupCfg, finish stagedsync.FinishCfg, caCfg stagedsync.ContractAnalyzerCfg, ots2Enabled bool, test bool) []*stagedsync.Stage {
+	defaultStages := stagedsync.DefaultStages(ctx, snapshots, headers, cumulativeIndex, blockHashCfg, bodies, senders, exec, hashState, trieCfg, history, logIndex, callTraces, txLookup, finish, caCfg, ots2Enabled, test)
+	// Remove body/headers stages
+	defaultStages[1].Forward = nullStage
+	defaultStages[4].Forward = nullStage
+	return defaultStages
+}
+
+func NewStagedSync(
+	ctx context.Context,
+	db kv.RwDB,
+	p2pCfg p2p.Config,
+	cfg *ethconfig.Config,
+	controlServer *sentry.MultiClient,
+	notifications *shards.Notifications,
+	snapDownloader proto_downloader.DownloaderClient,
+	agg *state.AggregatorV3,
+	forkValidator *engineapi.ForkValidator,
+	logger log.Logger,
+	blockReader services.FullBlockReader,
+	blockWriter *blockio.BlockWriter,
+	blockRetire services.BlockRetire,
+) (*stagedsync.Sync, error) {
+	dirs := cfg.Dirs
+
+	// During Import we don't want other services like header requests, body requests etc. to be running.
+	// Hence we run it in the test mode.
+	runInTestMode := cfg.ImportMode
+
+	return stagedsync.New(
+		ExecutionStages(ctx, cfg.Prune,
+			stagedsync.StageSnapshotsCfg(db, *controlServer.ChainConfig, dirs, blockRetire, snapDownloader, blockReader, notifications.Events, cfg.HistoryV3, agg),
+			stagedsync.StageHeadersCfg(db, controlServer.Hd, controlServer.Bd, *controlServer.ChainConfig, controlServer.SendHeaderRequest, controlServer.PropagateNewBlockHashes, controlServer.Penalize, cfg.BatchSize, p2pCfg.NoDiscovery, blockReader, blockWriter, dirs.Tmp, notifications, forkValidator),
+			stagedsync.StageCumulativeIndexCfg(db, blockReader),
+			stagedsync.StageBlockHashesCfg(db, dirs.Tmp, controlServer.ChainConfig, blockWriter),
+			stagedsync.StageBodiesCfg(db, controlServer.Bd, controlServer.SendBodyRequest, controlServer.Penalize, controlServer.BroadcastNewBlock, cfg.Sync.BodyDownloadTimeoutSeconds, *controlServer.ChainConfig, blockReader, cfg.HistoryV3, blockWriter),
+			stagedsync.StageSendersCfg(db, controlServer.ChainConfig, false, dirs.Tmp, cfg.Prune, blockReader, controlServer.Hd),
+			stagedsync.StageExecuteBlocksCfg(
+				db,
+				cfg.Prune,
+				cfg.BatchSize,
+				nil,
+				controlServer.ChainConfig,
+				controlServer.Engine,
+				&vm.Config{},
+				notifications.Accumulator,
+				cfg.StateStream,
+				/*stateStream=*/ false,
+				cfg.HistoryV3,
+				dirs,
+				blockReader,
+				controlServer.Hd,
+				cfg.Genesis,
+				cfg.Sync,
+				agg,
+			),
+			stagedsync.StageHashStateCfg(db, dirs, cfg.HistoryV3),
+			stagedsync.StageTrieCfg(db, true, true, false, dirs.Tmp, blockReader, controlServer.Hd, cfg.HistoryV3, agg),
+			stagedsync.StageHistoryCfg(db, cfg.Prune, dirs.Tmp),
+			stagedsync.StageLogIndexCfg(db, cfg.Prune, dirs.Tmp),
+			stagedsync.StageCallTracesCfg(db, cfg.Prune, 0, dirs.Tmp),
+			stagedsync.StageTxLookupCfg(db, cfg.Prune, dirs.Tmp, controlServer.ChainConfig.Bor, blockReader),
+			stagedsync.StageFinishCfg(db, dirs.Tmp, forkValidator),
+			stagedsync.StageDbAwareCfg(db, dirs.Tmp, controlServer.ChainConfig, blockReader, controlServer.Engine),
+			cfg.Ots2,
+			runInTestMode),
+		stagedsync.DefaultUnwindOrder,
+		stagedsync.DefaultPruneOrder,
+		logger,
+	), nil
+}