release(v4.6.0): broadcast channels — Signal sender-keys for one-to-many fan-out

Lands the broadcast-channel primitive Prism asked for in
Docs/shade-feature-request-sender-keys.md. The crypto in
@shade/core/sender-keys.ts was already in place; this release wires
it up as a first-class app-facing API, adds the persistence schema
across all six storage backends (memory, sqlite, indexeddb +
encrypted variants), introduces wire type 0x21 in @shade/proto,
and ships Prism's three acceptance tests verbatim.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/shade-storage-encrypted/src/storage/encrypted-sqlite.ts

@@ -1,5 +1,7 @@
 import { Database } from 'bun:sqlite';
 import type {
+  BroadcastChannelRecord,
+  BroadcastMemberRecord,
   IdentityKeyPair,
   OneTimePreKey,
   PeerVerification,
@@ -13,10 +15,10 @@ import type {
 import { constantTimeEqual, toBase64 } from '@shade/core';
 import { KeyManager } from '../crypto/key-manager.js';
 import {
-  openConfig, openIdentity, openOneTimePreKey, openRetired, openSession,
-  openSignedPreKey, openStreamSensitive, openTrust, sealConfig, sealIdentity,
-  sealOneTimePreKey, sealRetired, sealSession, sealSignedPreKey,
-  sealStreamSensitive, sealTrust,
+  openBroadcastChannelSensitive, openConfig, openIdentity, openOneTimePreKey, openRetired,
+  openSession, openSignedPreKey, openStreamSensitive, openTrust,
+  sealBroadcastChannelSensitive, sealConfig, sealIdentity, sealOneTimePreKey,
+  sealRetired, sealSession, sealSignedPreKey, sealStreamSensitive, sealTrust,
 } from '../crypto/row-codec.js';
 
 /**
@@ -68,6 +70,14 @@ export class EncryptedSQLiteStorage implements StorageProvider {
     removePeerVerification:     ReturnType<Database['prepare']>;
     getPeerIdentityVersion:     ReturnType<Database['prepare']>;
     upsertPeerIdentityVersion:  ReturnType<Database['prepare']>;
+    saveBroadcastChannel:       ReturnType<Database['prepare']>;
+    getBroadcastChannel:        ReturnType<Database['prepare']>;
+    listBroadcastChannels:      ReturnType<Database['prepare']>;
+    removeBroadcastChannel:     ReturnType<Database['prepare']>;
+    removeBroadcastChannelMembers: ReturnType<Database['prepare']>;
+    saveBroadcastMember:        ReturnType<Database['prepare']>;
+    getBroadcastMembers:        ReturnType<Database['prepare']>;
+    removeBroadcastMember:      ReturnType<Database['prepare']>;
   };
 
   private constructor(db: Database, km: KeyManager, ownsDb: boolean) {
@@ -156,6 +166,24 @@ export class EncryptedSQLiteStorage implements StorageProvider {
         peer_address TEXT PRIMARY KEY,
         version      INTEGER NOT NULL
       );
+      CREATE TABLE IF NOT EXISTS broadcast_channels_enc (
+        channel_id    TEXT PRIMARY KEY,
+        owner_role    TEXT NOT NULL,
+        owner_address TEXT NOT NULL,
+        label         TEXT,
+        generation    INTEGER NOT NULL,
+        ciphertext    BLOB NOT NULL,
+        created_at    INTEGER NOT NULL,
+        updated_at    INTEGER NOT NULL
+      );
+      CREATE TABLE IF NOT EXISTS broadcast_members_enc (
+        channel_id   TEXT NOT NULL,
+        peer_address TEXT NOT NULL,
+        joined_at    INTEGER NOT NULL,
+        removed_at   INTEGER,
+        PRIMARY KEY (channel_id, peer_address)
+      );
+      CREATE INDEX IF NOT EXISTS idx_broadcast_members_enc_channel ON broadcast_members_enc(channel_id);
     `);
   }
 
@@ -212,6 +240,35 @@ export class EncryptedSQLiteStorage implements StorageProvider {
         `INSERT INTO peer_identity_versions_enc (peer_address, version) VALUES (?, ?)
          ON CONFLICT(peer_address) DO UPDATE SET version = excluded.version`,
       ),
+      saveBroadcastChannel: this.db.prepare(
+        `INSERT OR REPLACE INTO broadcast_channels_enc
+           (channel_id, owner_role, owner_address, label, generation,
+            ciphertext, created_at, updated_at)
+         VALUES (?, ?, ?, ?, ?, ?, ?, ?)`,
+      ),
+      getBroadcastChannel: this.db.prepare(
+        'SELECT * FROM broadcast_channels_enc WHERE channel_id = ?',
+      ),
+      listBroadcastChannels: this.db.prepare(
+        'SELECT * FROM broadcast_channels_enc ORDER BY created_at ASC',
+      ),
+      removeBroadcastChannel: this.db.prepare(
+        'DELETE FROM broadcast_channels_enc WHERE channel_id = ?',
+      ),
+      removeBroadcastChannelMembers: this.db.prepare(
+        'DELETE FROM broadcast_members_enc WHERE channel_id = ?',
+      ),
+      saveBroadcastMember: this.db.prepare(
+        `INSERT OR REPLACE INTO broadcast_members_enc
+           (channel_id, peer_address, joined_at, removed_at)
+         VALUES (?, ?, ?, ?)`,
+      ),
+      getBroadcastMembers: this.db.prepare(
+        'SELECT channel_id, peer_address, joined_at, removed_at FROM broadcast_members_enc WHERE channel_id = ? ORDER BY joined_at ASC',
+      ),
+      removeBroadcastMember: this.db.prepare(
+        'DELETE FROM broadcast_members_enc WHERE channel_id = ? AND peer_address = ?',
+      ),
     };
   }
 
@@ -432,6 +489,88 @@ export class EncryptedSQLiteStorage implements StorageProvider {
     return next;
   }
 
+  // ─── Broadcast channels (V4.6) ────────────────────────────
+
+  async saveBroadcastChannel(channel: BroadcastChannelRecord): Promise<void> {
+    const sealed = await sealBroadcastChannelSensitive(this.km, channel.channelId, {
+      chainKey: channel.chainKey,
+      iteration: channel.iteration,
+      signingPublicKey: channel.signingPublicKey,
+      ...(channel.signingPrivateKey !== undefined ? { signingPrivateKey: channel.signingPrivateKey } : {}),
+    });
+    this.stmts.saveBroadcastChannel.run(
+      channel.channelId,
+      channel.ownerRole,
+      channel.ownerAddress,
+      channel.label ?? null,
+      channel.generation,
+      sealed,
+      channel.createdAt,
+      channel.updatedAt,
+    );
+  }
+
+  async getBroadcastChannel(channelId: string): Promise<BroadcastChannelRecord | null> {
+    const row = this.stmts.getBroadcastChannel.get(channelId) as BroadcastChannelEncRow | undefined;
+    if (!row) return null;
+    return this.encRowToChannel(row);
+  }
+
+  async listBroadcastChannels(): Promise<BroadcastChannelRecord[]> {
+    const rows = this.stmts.listBroadcastChannels.all() as BroadcastChannelEncRow[];
+    return Promise.all(rows.map((r) => this.encRowToChannel(r)));
+  }
+
+  async removeBroadcastChannel(channelId: string): Promise<void> {
+    this.stmts.removeBroadcastChannelMembers.run(channelId);
+    this.stmts.removeBroadcastChannel.run(channelId);
+  }
+
+  async saveBroadcastMember(member: BroadcastMemberRecord): Promise<void> {
+    this.stmts.saveBroadcastMember.run(
+      member.channelId,
+      member.peerAddress,
+      member.joinedAt,
+      member.removedAt,
+    );
+  }
+
+  async getBroadcastMembers(channelId: string): Promise<BroadcastMemberRecord[]> {
+    const rows = this.stmts.getBroadcastMembers.all(channelId) as BroadcastMemberEncRow[];
+    return rows.map((r) => ({
+      channelId: r.channel_id,
+      peerAddress: r.peer_address,
+      joinedAt: Number(r.joined_at),
+      removedAt: r.removed_at === null || r.removed_at === undefined ? null : Number(r.removed_at),
+    }));
+  }
+
+  async removeBroadcastMember(channelId: string, peerAddress: string): Promise<void> {
+    this.stmts.removeBroadcastMember.run(channelId, peerAddress);
+  }
+
+  private async encRowToChannel(row: BroadcastChannelEncRow): Promise<BroadcastChannelRecord> {
+    const sensitive = await openBroadcastChannelSensitive(
+      this.km,
+      row.channel_id,
+      toBytes(row.ciphertext),
+    );
+    const out: BroadcastChannelRecord = {
+      channelId: row.channel_id,
+      ownerRole: row.owner_role,
+      ownerAddress: row.owner_address,
+      generation: Number(row.generation),
+      chainKey: sensitive.chainKey,
+      iteration: sensitive.iteration,
+      signingPublicKey: sensitive.signingPublicKey,
+      createdAt: Number(row.created_at),
+      updatedAt: Number(row.updated_at),
+    };
+    if (row.label !== null && row.label !== undefined) out.label = row.label;
+    if (sensitive.signingPrivateKey !== undefined) out.signingPrivateKey = sensitive.signingPrivateKey;
+    return out;
+  }
+
   private async rowToStreamState(row: StreamRow): Promise<PersistedStreamState> {
     const sensitive = await openStreamSensitive(this.km, row.stream_id, toBytes(row.ciphertext));
     const out: PersistedStreamState = {
@@ -463,6 +602,24 @@ interface StreamRow {
   updated_at: number | bigint;
 }
 
+interface BroadcastChannelEncRow {
+  channel_id: string;
+  owner_role: 'sender' | 'receiver';
+  owner_address: string;
+  label: string | null;
+  generation: number | bigint;
+  ciphertext: Uint8Array | ArrayBuffer;
+  created_at: number | bigint;
+  updated_at: number | bigint;
+}
+
+interface BroadcastMemberEncRow {
+  channel_id: string;
+  peer_address: string;
+  joined_at: number | bigint;
+  removed_at: number | bigint | null;
+}
+
 function toBytes(value: Uint8Array | ArrayBuffer | unknown): Uint8Array {
   if (value instanceof Uint8Array) return value;
   if (value instanceof ArrayBuffer) return new Uint8Array(value);