feat: implement server pairing confirmation flow

plugin/core/runtime.ts

@@ -1,9 +1,13 @@
 import {
   type BuiltinEnvelope,
   type HelloPayload,
+  type PairConfirmPayload,
   YONEXUS_PROTOCOL_VERSION,
   buildError,
   buildHelloAck,
+  buildPairFailed,
+  buildPairRequest,
+  buildPairSuccess,
   decodeBuiltin,
   encodeBuiltin,
   isBuiltinMessage
@@ -125,6 +129,14 @@ export class YonexusServerRuntime {
 
     if (envelope.type === "hello") {
       await this.handleHello(connection, envelope as BuiltinEnvelope<"hello", HelloPayload>);
+      return;
+    }
+
+    if (envelope.type === "pair_confirm") {
+      await this.handlePairConfirm(
+        connection,
+        envelope as BuiltinEnvelope<"pair_confirm", PairConfirmPayload>
+      );
     }
   }
 
@@ -176,7 +188,8 @@ export class YonexusServerRuntime {
       socket: connection.ws,
       isAuthenticated: false,
       connectedAt: connection.connectedAt,
-      lastActivityAt: this.now()
+      lastActivityAt: this.now(),
+      publicKey: payload.publicKey
     });
 
     const nextAction = this.determineNextAction(record);
@@ -193,13 +206,113 @@ export class YonexusServerRuntime {
       )
     );
 
-    if (nextAction === "pair_required") {
-      await this.beginPairing(record);
+    if (nextAction === "pair_required" || nextAction === "waiting_pair_confirm") {
+      await this.beginPairing({
+        record,
+        connection: { ...connection, identifier: helloIdentifier },
+        requestId: envelope.requestId,
+        reusePending: nextAction === "waiting_pair_confirm"
+      });
     }
 
     await this.persist();
   }
 
+  private async handlePairConfirm(
+    connection: ClientConnection,
+    envelope: BuiltinEnvelope<"pair_confirm", PairConfirmPayload>
+  ): Promise<void> {
+    const payload = envelope.payload;
+    if (!payload) {
+      this.options.transport.sendToConnection(
+        connection,
+        encodeBuiltin(
+          buildError(
+            { code: "MALFORMED_MESSAGE", message: "pair_confirm payload is required" },
+            { requestId: envelope.requestId, timestamp: this.now() }
+          )
+        )
+      );
+      return;
+    }
+
+    const identifier = payload.identifier?.trim();
+    if (!identifier || !this.options.config.followerIdentifiers.includes(identifier)) {
+      this.options.transport.sendToConnection(
+        connection,
+        encodeBuiltin(
+          buildPairFailed(
+            {
+              identifier: identifier || "unknown",
+              reason: "identifier_not_allowed"
+            },
+            { requestId: envelope.requestId, timestamp: this.now() }
+          )
+        )
+      );
+      return;
+    }
+
+    const record = this.ensureClientRecord(identifier);
+    const submittedCode = payload.pairingCode?.trim();
+    if (!submittedCode) {
+      this.options.transport.sendToConnection(
+        connection,
+        encodeBuiltin(
+          buildError(
+            { code: "MALFORMED_MESSAGE", message: "pairingCode is required" },
+            { requestId: envelope.requestId, timestamp: this.now() }
+          )
+        )
+      );
+      return;
+    }
+
+    const result = this.pairingService.confirmPairing(record, submittedCode);
+    if (!result.success || !result.secret || !result.pairedAt) {
+      const reason = result.reason === "not_pending" ? "internal_error" : result.reason ?? "internal_error";
+      this.options.transport.sendToConnection(
+        connection,
+        encodeBuiltin(
+          buildPairFailed(
+            {
+              identifier,
+              reason
+            },
+            { requestId: envelope.requestId, timestamp: this.now() }
+          )
+        )
+      );
+
+      await this.persist();
+      return;
+    }
+
+    if (connection.identifier !== identifier) {
+      this.options.transport.registerConnection(identifier, connection.ws);
+    }
+
+    const session = this.registry.sessions.get(identifier);
+    record.publicKey = session?.publicKey ?? record.publicKey;
+    record.updatedAt = this.now();
+
+    this.options.transport.sendToConnection(
+      { ...connection, identifier },
+      encodeBuiltin(
+        buildPairSuccess(
+          {
+            identifier,
+            secret: result.secret,
+            pairedAt: result.pairedAt
+          },
+          { requestId: envelope.requestId, timestamp: this.now() }
+        )
+      )
+    );
+
+    await this.persist();
+  }
+
   private determineNextAction(record: ClientRecord): "pair_required" | "auth_required" | "waiting_pair_confirm" {
     if (hasPendingPairing(record) && !isPairingExpired(record, this.now())) {
       return "waiting_pair_confirm";
@@ -223,18 +336,66 @@ export class YonexusServerRuntime {
     return created;
   }
 
-  private async beginPairing(record: ClientRecord): Promise<void> {
-    if (hasPendingPairing(record) && !isPairingExpired(record, this.now())) {
-      return;
-    }
+  private async beginPairing(options: {
+    record: ClientRecord;
+    connection: ClientConnection;
+    requestId?: string;
+    reusePending?: boolean;
+  }): Promise<void> {
+    const { record, connection, requestId, reusePending = false } = options;
+
+    const request =
+      reusePending && hasPendingPairing(record) && !isPairingExpired(record, this.now())
+        ? {
+            identifier: record.identifier,
+            pairingCode: record.pairingCode ?? "",
+            expiresAt: record.pairingExpiresAt ?? this.now(),
+            ttlSeconds: this.pairingService.getRemainingTtl(record),
+            createdAt: record.updatedAt
+          }
+        : this.pairingService.createPairingRequest(record);
+
+    const notified = reusePending
+      ? record.pairingNotifyStatus === "sent"
+      : await this.notificationService.sendPairingNotification(request);
 
-    const request = this.pairingService.createPairingRequest(record);
-    const notified = await this.notificationService.sendPairingNotification(request);
     if (notified) {
       this.pairingService.markNotificationSent(record);
     } else {
       this.pairingService.markNotificationFailed(record);
     }
+
+    this.options.transport.sendToConnection(
+      connection,
+      encodeBuiltin(
+        buildPairRequest(
+          {
+            identifier: record.identifier,
+            expiresAt: request.expiresAt,
+            ttlSeconds: this.pairingService.getRemainingTtl(record),
+            adminNotification: notified ? "sent" : "failed",
+            codeDelivery: "out_of_band"
+          },
+          { requestId, timestamp: this.now() }
+        )
+      )
+    );
+
+    if (!notified) {
+      this.options.transport.sendToConnection(
+        connection,
+        encodeBuiltin(
+          buildPairFailed(
+            {
+              identifier: record.identifier,
+              reason: "admin_notification_failed"
+            },
+            { requestId, timestamp: this.now() }
+          )
+        )
+      );
+      this.pairingService.clearPairingState(record);
+    }
   }
 
   private async persist(): Promise<void> {