## Summary

A sweep of the repo's **unconditionally-disabled tests** — `t.Skip(...)`
not gated on `testing.Short()`. This removes **24** such skips, either
by fixing the underlying behavior or by converting permanent skips into
clean precondition gates (live node, snapshot file, env var, RAM) that
run when the resource is present and skip cleanly when it isn't. What's
intentionally left skipped is listed below.

(Out of scope: `testing.Short()` skips, Windows/race-guarded skips,
runtime precondition guards, and commented-out skips.)

## t8n / `cmd/evm` (the meaty part)

Un-skipping `TestT8n` surfaced **5 stacked bugs**, all fixed here:

1. `getTransaction` dropped the JSON `v/r/s`, so signed txs got a zero
signature → `ErrInvalidSig`. Now preserves V/R/S (new
`TestGetTransactionPreservesSignature`).
2. **E3 state plumbing** — `MakePreState` read base state from `tx`
while writing to `SharedDomains` (execution saw balance 0), and
`CalculateStateRoot` used a fresh `SharedDomains` (→ empty-trie root).
Now reads/commits on the same `sd` that executed, then flushes and
records the block→txNum so the alloc dumper sees the post-state.
3. `EphemeralExecResult.Difficulty` now serializes as hex
(`*math.HexOrDecimal256`), matching the spec. (Only non-test change; the
field is marshaled solely by t8n.)
4. A blockhash requested but missing from the env now yields exit code 4
instead of a silent tx rejection.
5. Empty receipts serialize as `null`, matching the reference output.

## Deliberately left skipped

- **`node/app/component` gomock tests** (`TestComponentLifecycle`,
`TestDomainLifecycle`, `TestAddRemoveDeps`) — left skipped; this PR
doesn't touch them. The whole package is disabled by a pre-existing
`TestMain` `os.Exit(0)`; re-enabling it exposes a data race (fixed in
erigontech#21551) plus a flaky test and a goroutine-leak deadlock, tracked in
erigontech#21552.
- **HexPatriciaHashed traps** — `Test_ModeUpdate_SiblingConsistency`
(erigontech#20961) and `Test_HexPatriciaHashed_StateRestoreAndContinue`
(concurrent map write): consensus-critical, left as regression markers.
- **Feature-gated** — `execmodule` background-commit and
`component/fuzz_test` wait on features not yet built.
- **`node.TestRegisterProtocols`** — empty `// TODO` stub for p2p
registration that moved to sentry; recommend deleting.
- **Likely real bugs, left for owner judgment** —
`execution/state.TestCreateOnExistingStorage` (Erigon keeps pre-existing
storage on CREATE-over; go-ethereum clears it) and
`db/test.Test_AggregatorV3_RestartOnDatadir_{WithoutDB,WithoutAnything}`
(restart-from-files-without-DB fails `commitmentdb` freshness).

## Testing

`make lint` clean, `make erigon integration` builds, and every touched
test passes (resource-gated ones skip cleanly without their resources).
Latest `main` is merged in, which brings erigontech#21505's removal of the legacy
`headerdownload` / `bodydownload` / `dataflow` packages.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: info@weblogix.biz <admin@10gbps.weblogix.it>