feat(nodes): gRPC server + Hub + Redis pub/sub cross-instance delivery (tsk__58l3wTLvaSn)

Implements AgentService gRPC server with all 6 RPCs (Enroll/Register/Heartbeat/
Subscribe/Ack/ReportUsage), Hub command routing with Redis ZSET at-least-once
persistence and cross-instance pub/sub delivery, LoadCache for node:load metrics,
NodeStore SQL interface + MySQL implementation, and full mTLS gRPC listener in main.

Integration tests: 18 tests covering full Enroll→Register→Heartbeat→Subscribe→Ack
flow, reconnect resume with last_command_id, and cross-instance pub/sub delivery
via bufconn + miniredis + mockNodeStore + real mTLS certificates.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/internal/nodes/store.go

@@ -0,0 +1,158 @@
+package nodes
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"time"
+
+	agentv1 "github.com/wangjia/pangolin/server/internal/pb/agentv1"
+)
+
+// NodeRow holds a node's essential fields from the nodes table.
+type NodeRow struct {
+	ID         int64
+	UUID       string
+	Status     string
+	RealityPBK string
+	RealitySNI string
+	Endpoint   string
+	Hy2Port    sql.NullInt32
+}
+
+// NodeStore is the persistence interface used by the nodes domain handlers.
+// All methods are context-aware and safe for concurrent use.
+type NodeStore interface {
+	// NodeByUUID looks up a node record by its UUID.
+	// Returns (nil, nil) when no matching row exists.
+	NodeByUUID(ctx context.Context, uuid string) (*NodeRow, error)
+
+	// ConfigVersion returns the current global directory version.
+	// This is the version from the directory_version singleton table.
+	ConfigVersion(ctx context.Context) (int64, error)
+
+	// ActiveNodeUUIDs returns the UUIDs of all nodes with status 'up' or 'draining'.
+	// Used by Broadcast to enumerate delivery targets.
+	ActiveNodeUUIDs(ctx context.Context) ([]string, error)
+
+	// CredentialsForNode returns the active data-plane credentials for nodeUUID.
+	// Returns an empty slice until task 5d creates the connect_credentials table.
+	CredentialsForNode(ctx context.Context, nodeUUID string) ([]*agentv1.Credential, error)
+
+	// UserIDByDpUUID maps a data-plane UUID to the owning user's internal ID.
+	// Returns (0, false, nil) if the dp_uuid is unknown or the user is inactive.
+	UserIDByDpUUID(ctx context.Context, dpUUID string) (int64, bool, error)
+
+	// AccumulateUsage adds bytes and minutes to usage_daily for userID on date.
+	// Uses INSERT … ON DUPLICATE KEY UPDATE (idempotent within a day).
+	AccumulateUsage(ctx context.Context, userID int64, date time.Time,
+		bytesUp, bytesDown int64, minutes int64) error
+}
+
+// SQLNodeStore implements NodeStore against a MySQL 8.x database.
+type SQLNodeStore struct {
+	db *sql.DB
+}
+
+// NewSQLNodeStore creates a SQLNodeStore backed by db.
+func NewSQLNodeStore(db *sql.DB) *SQLNodeStore {
+	return &SQLNodeStore{db: db}
+}
+
+// NodeByUUID looks up a node by UUID. Returns (nil, nil) when not found.
+func (s *SQLNodeStore) NodeByUUID(ctx context.Context, uuid string) (*NodeRow, error) {
+	const q = `
+		SELECT id, uuid, status, reality_pbk, reality_sni, endpoint, hy2_port
+		FROM nodes
+		WHERE uuid = ?
+	`
+	var n NodeRow
+	err := s.db.QueryRowContext(ctx, q, uuid).Scan(
+		&n.ID, &n.UUID, &n.Status,
+		&n.RealityPBK, &n.RealitySNI, &n.Endpoint, &n.Hy2Port,
+	)
+	if err == sql.ErrNoRows {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, fmt.Errorf("nodes.SQLNodeStore.NodeByUUID: %w", err)
+	}
+	return &n, nil
+}
+
+// ConfigVersion returns the current global directory version.
+// Returns 0 with nil error if the directory_version row does not yet exist.
+func (s *SQLNodeStore) ConfigVersion(ctx context.Context) (int64, error) {
+	var v int64
+	err := s.db.QueryRowContext(ctx,
+		`SELECT version FROM directory_version WHERE id = 1`).Scan(&v)
+	if err == sql.ErrNoRows {
+		return 0, nil
+	}
+	if err != nil {
+		return 0, fmt.Errorf("nodes.SQLNodeStore.ConfigVersion: %w", err)
+	}
+	return v, nil
+}
+
+// ActiveNodeUUIDs returns UUIDs of all nodes with status 'up' or 'draining'.
+func (s *SQLNodeStore) ActiveNodeUUIDs(ctx context.Context) ([]string, error) {
+	rows, err := s.db.QueryContext(ctx,
+		`SELECT uuid FROM nodes WHERE status IN ('up', 'draining')`)
+	if err != nil {
+		return nil, fmt.Errorf("nodes.SQLNodeStore.ActiveNodeUUIDs: %w", err)
+	}
+	defer rows.Close()
+
+	var uuids []string
+	for rows.Next() {
+		var u string
+		if err := rows.Scan(&u); err != nil {
+			return nil, fmt.Errorf("nodes.SQLNodeStore.ActiveNodeUUIDs scan: %w", err)
+		}
+		uuids = append(uuids, u)
+	}
+	return uuids, rows.Err()
+}
+
+// CredentialsForNode returns active credentials for nodeUUID.
+// Stub: returns empty slice until task 5d creates the connect_credentials table.
+func (s *SQLNodeStore) CredentialsForNode(_ context.Context, _ string) ([]*agentv1.Credential, error) {
+	return nil, nil
+}
+
+// UserIDByDpUUID resolves a data-plane UUID to an active user's internal ID.
+func (s *SQLNodeStore) UserIDByDpUUID(ctx context.Context, dpUUID string) (int64, bool, error) {
+	var userID int64
+	err := s.db.QueryRowContext(ctx,
+		`SELECT id FROM users WHERE dp_uuid = ? AND status = 'active' LIMIT 1`, dpUUID,
+	).Scan(&userID)
+	if err == sql.ErrNoRows {
+		return 0, false, nil
+	}
+	if err != nil {
+		return 0, false, fmt.Errorf("nodes.SQLNodeStore.UserIDByDpUUID: %w", err)
+	}
+	return userID, true, nil
+}
+
+// AccumulateUsage adds bytes/minutes to usage_daily for the given user and date.
+func (s *SQLNodeStore) AccumulateUsage(
+	ctx context.Context, userID int64, date time.Time,
+	bytesUp, bytesDown int64, minutes int64,
+) error {
+	const q = `
+		INSERT INTO usage_daily (user_id, date, bytes_up, bytes_down, minutes_used)
+		VALUES (?, ?, ?, ?, ?)
+		ON DUPLICATE KEY UPDATE
+			bytes_up     = bytes_up     + VALUES(bytes_up),
+			bytes_down   = bytes_down   + VALUES(bytes_down),
+			minutes_used = minutes_used + VALUES(minutes_used)
+	`
+	if _, err := s.db.ExecContext(ctx, q,
+		userID, date.Format("2006-01-02"), bytesUp, bytesDown, minutes,
+	); err != nil {
+		return fmt.Errorf("nodes.SQLNodeStore.AccumulateUsage: %w", err)
+	}
+	return nil
+}