chore: repack USB + add 44 critical missing tests. Rebuilt agent+server binaries: RandomX SuperScalar init, fast Stratum fallback 8s/15s, GPU shutdown fix, RVN pool rotation, wallets baked. Tests: handleMessage dispatch, needsStratumFallback thresholds, IsGuardMode, pool parseAndSetJob, difficultyToTarget, parseSubmitResult, ParseBlob, FromModelJob round-trip.

usb/agent/miner/engine.go

@@ -0,0 +1,75 @@
+package miner
+
+import (
+	"encoding/hex"
+	"sync"
+
+	"git.gammaspectra.live/P2Pool/go-randomx"
+)
+
+const nonceOffset = 39
+const nonceSize = 4
+
+// go-randomx is a pure-Go implementation; hardware flags are ignored internally.
+const randomxFlags = 0
+
+type Engine struct {
+	mu      sync.RWMutex
+	cache   *randomx.Randomx_Cache
+	vm      *randomx.VM
+	seedHex string
+	blob    []byte
+}
+
+func NewEngine() *Engine {
+	cache := randomx.Randomx_alloc_cache(randomxFlags)
+	return &Engine{cache: cache}
+}
+
+func (e *Engine) SetJob(seedHex, blobHex string) error {
+	seed, err := hex.DecodeString(seedHex)
+	if err != nil {
+		return err
+	}
+	blob, err := hex.DecodeString(blobHex)
+	if err != nil {
+		return err
+	}
+
+	e.mu.Lock()
+	defer e.mu.Unlock()
+
+	if e.seedHex != seedHex {
+		e.cache.Randomx_init_cache(seed)
+		// go-randomx requires SuperScalar programs to be built separately after
+		// seeding the cache; Randomx_init_cache only populates the Argon2d blocks.
+		// Without this step every CalculateHash call crashes with a nil-pointer.
+		gen := randomx.Init_Blake2Generator(seed, 0)
+		for i := range e.cache.Programs {
+			e.cache.Programs[i] = randomx.Build_SuperScalar_Program(gen)
+		}
+		e.vm = e.cache.VM_Initialize()
+		e.seedHex = seedHex
+	}
+	e.blob = append([]byte(nil), blob...)
+	return nil
+}
+
+func (e *Engine) HashAtNonce(nonce uint32) (hashHex string, blobHex string, err error) {
+	e.mu.RLock()
+	defer e.mu.RUnlock()
+
+	if e.vm == nil || len(e.blob) < nonceOffset+nonceSize {
+		return "", "", nil
+	}
+
+	work := append([]byte(nil), e.blob...)
+	work[nonceOffset] = byte(nonce)
+	work[nonceOffset+1] = byte(nonce >> 8)
+	work[nonceOffset+2] = byte(nonce >> 16)
+	work[nonceOffset+3] = byte(nonce >> 24)
+
+	out := make([]byte, 32)
+	e.vm.CalculateHash(work, out)
+	return hex.EncodeToString(out), hex.EncodeToString(work), nil
+}