feat(api+broker+web): write-time mention fan-out via notification table

Phase 1 of v0.3.0 — replaces the regex-on-decoded-ciphertext scan
in /v1/notifications and the dashboard MentionsSection with reads
from a new mesh.notification table populated at write time.

Schema 0025: mesh.notification (id, mesh_id, topic_id, message_id,
recipient_member_id, sender_member_id, kind, created_at, read_at)
with a unique (message_id, recipient) so a re-fanned message yields
one row per recipient. Backfills existing v0.2.0 messages by
regex-matching the (still-base64-plaintext) bodies — guarded with
a base64 + length check so binary ciphertext doesn't crash the
migration.

Writers (POST /v1/messages + broker appendTopicMessage) now
extract @-mentions from either an explicit `mentions: string[]`
on the request OR a regex over the base64 plaintext (transitional
fallback). Targets are intersected with the mesh roster + capped
at 32 per message. Web chat panel sends the explicit array now so
it keeps working after phase 2 lands.

Readers switch to JOIN-on-notification:
  /v1/notifications      — table-backed, supports ?unread=1
  POST /v1/notifications/read  — new, mark by ids or all-up-to
  MentionsSection (RSC) — same JOIN, returns readAt for each row

GET /v1/notifications also gains a read_at field per row so a
future bell UI can show unread vs read.

Once per-topic encryption (phase 2) lands, the regex fallback
becomes a no-op for v2 messages — clients MUST send `mentions`,
which they already do.

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

apps/broker/src/broker.ts

@@ -38,7 +38,9 @@ import {
   meshFileKey,
   meshContext,
   meshMember as memberTable,
+  meshMember,
   meshMemory,
+  meshNotification,
   meshState,
   meshService,
   meshSkill,
@@ -694,6 +696,13 @@ export async function appendTopicMessage(args: {
   senderSessionPubkey?: string;
   nonce: string;
   ciphertext: string;
+  /**
+   * Optional client-extracted mention list (lowercased display names
+   * without the leading @). Required once per-topic encryption lands —
+   * the server can't read v0.3.0 ciphertext. Falls back to a regex on
+   * the v0.2.0 base64 plaintext when omitted.
+   */
+  mentions?: string[];
 }): Promise<string> {
   const [row] = await db
     .insert(meshTopicMessage)
@@ -706,9 +715,94 @@ export async function appendTopicMessage(args: {
     })
     .returning({ id: meshTopicMessage.id });
   if (!row) throw new Error("failed to append topic message");
+
+  void fanOutMentions({
+    messageId: row.id,
+    topicId: args.topicId,
+    senderMemberId: args.senderMemberId,
+    ciphertext: args.ciphertext,
+    explicit: args.mentions,
+  }).catch(() => {
+    // Notifications are advisory; don't fail the message write.
+  });
+
   return row.id;
 }
 
+/**
+ * Extract `@<displayName>` tokens from a base64-of-UTF8 plaintext body.
+ * Capped at 16 tokens. Returns lowercased names without the @ prefix.
+ */
+function extractMentionTokens(b64: string): string[] {
+  let text: string;
+  try {
+    text = Buffer.from(b64, "base64").toString("utf-8");
+  } catch {
+    return [];
+  }
+  const found = new Set<string>();
+  const re = /(^|[^A-Za-z0-9_-])@([A-Za-z0-9_-]{1,64})(?=$|[^A-Za-z0-9_-])/g;
+  let m: RegExpExecArray | null;
+  while ((m = re.exec(text)) !== null) {
+    found.add(m[2]!.toLowerCase());
+    if (found.size >= 16) break;
+  }
+  return [...found];
+}
+
+async function fanOutMentions(args: {
+  messageId: string;
+  topicId: string;
+  senderMemberId: string;
+  ciphertext: string;
+  explicit?: string[];
+}): Promise<void> {
+  let tokens = args.explicit?.map((s) => s.toLowerCase().replace(/^@/, ""));
+  if (!tokens || tokens.length === 0) {
+    tokens = extractMentionTokens(args.ciphertext);
+  }
+  if (tokens.length === 0) return;
+
+  const [topic] = await db
+    .select({ meshId: meshTopic.meshId })
+    .from(meshTopic)
+    .where(eq(meshTopic.id, args.topicId));
+  if (!topic) return;
+
+  const recipients = await db
+    .select({
+      id: meshMember.id,
+      displayName: meshMember.displayName,
+    })
+    .from(meshMember)
+    .where(
+      and(eq(meshMember.meshId, topic.meshId), isNull(meshMember.revokedAt)),
+    );
+  const tokenSet = new Set(tokens);
+  const targets = recipients
+    .filter(
+      (r) =>
+        tokenSet.has(r.displayName.toLowerCase()) &&
+        r.id !== args.senderMemberId,
+    )
+    .slice(0, 32);
+  if (targets.length === 0) return;
+
+  await db
+    .insert(meshNotification)
+    .values(
+      targets.map((t) => ({
+        meshId: topic.meshId,
+        topicId: args.topicId,
+        messageId: args.messageId,
+        recipientMemberId: t.id,
+        senderMemberId: args.senderMemberId,
+        kind: "mention",
+      })),
+    )
+    .onConflictDoNothing();
+}
+
 /**
  * Fetch topic history for a member. Pagination via `before` cursor (id of
  * an earlier message); pass null for the latest page.

apps/web/src/app/[locale]/dashboard/(user)/page.tsx

@@ -9,11 +9,12 @@ import { db } from "@turbostarter/db/server";
 import {
   mesh,
   meshMember,
+  meshNotification,
   meshTopic,
   meshTopicMember,
   meshTopicMessage,
 } from "@turbostarter/db/schema/mesh";
-import { and, count, desc, eq, gt, inArray, isNull, or, sql } from "drizzle-orm";
+import { aliasedTable, and, count, desc, eq, gt, inArray, isNull, or, sql } from "drizzle-orm";
 
 import { appConfig } from "~/config/app";
 import { pathsConfig } from "~/config/paths";
@@ -127,45 +128,42 @@ export default async function UniversePage() {
   }));
 
   // Recent @-mentions of the viewer across every mesh they belong to.
-  // Build a (memberId, regex) pair per mesh and OR them together so we
+  // Reads from mesh.notification, populated at write time by the
-  // catch users with different display names in different meshes. The
+  // POST /v1/messages handler + broker topic-send. Survives v0.3.0
-  // ciphertext is base64 plaintext in v0.2.0; per-topic encryption in
+  // per-topic encryption (the previous regex-on-decoded-ciphertext
-  // v0.3.0 will move this scan to a notification table populated at
+  // approach would not). 7-day window keeps the result bounded.
-  // write time. 7-day window keeps the query bounded.
   const mentionWindow = new Date(Date.now() - 7 * 24 * 60 * 60 * 1000);
-  const mentionConditions = myMembers.map((m) => {
+  const senderMember = aliasedTable(meshMember, "sender_member");
-    const escaped = m.displayName.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+  const mentionRows = myMemberIds.length
-    const pattern = `(^|\\s|[^A-Za-z0-9_-])@${escaped}($|[^A-Za-z0-9_-])`;
-    return and(
-      eq(meshTopic.meshId, m.meshId),
-      sql`${meshTopicMessage.senderMemberId} <> ${m.id}`,
-      sql`convert_from(decode(${meshTopicMessage.ciphertext}, 'base64'), 'UTF8') ~* ${pattern}`,
-    );
-  });
-  const mentionRows = mentionConditions.length
     ? await db
         .select({
           id: meshTopicMessage.id,
+          notificationId: meshNotification.id,
           topicId: meshTopicMessage.topicId,
           topicName: meshTopic.name,
           meshId: meshTopic.meshId,
           meshName: mesh.name,
-          senderName: meshMember.displayName,
+          senderName: senderMember.displayName,
           ciphertext: meshTopicMessage.ciphertext,
+          readAt: meshNotification.readAt,
           createdAt: meshTopicMessage.createdAt,
         })
-        .from(meshTopicMessage)
+        .from(meshNotification)
-        .innerJoin(meshTopic, eq(meshTopic.id, meshTopicMessage.topicId))
+        .innerJoin(
+          meshTopicMessage,
+          eq(meshTopicMessage.id, meshNotification.messageId),
+        )
+        .innerJoin(meshTopic, eq(meshTopic.id, meshNotification.topicId))
         .innerJoin(mesh, eq(mesh.id, meshTopic.meshId))
         .innerJoin(
-          meshMember,
+          senderMember,
-          eq(meshMember.id, meshTopicMessage.senderMemberId),
+          eq(senderMember.id, meshNotification.senderMemberId),
         )
         .where(
           and(
+            inArray(meshNotification.recipientMemberId, myMemberIds),
             isNull(meshTopic.archivedAt),
             gt(meshTopicMessage.createdAt, mentionWindow),
-            or(...mentionConditions),
           ),
         )
         .orderBy(desc(meshTopicMessage.createdAt))

apps/web/src/modules/mesh/topic-chat-panel.tsx

@@ -414,6 +414,21 @@ export function TopicChatPanel({
     [draft, mentionState],
   );
 
+  // Extract @-mention tokens from the draft body so the server can
+  // populate mesh.notification rows without having to read the
+  // ciphertext (forward-compat with v0.3.0 per-topic encryption).
+  // Capped at 16 to bound notification fan-out.
+  const extractMentions = (text: string): string[] => {
+    const found = new Set<string>();
+    const re = /(^|[^A-Za-z0-9_-])@([A-Za-z0-9_-]{1,64})(?=$|[^A-Za-z0-9_-])/g;
+    let m: RegExpExecArray | null;
+    while ((m = re.exec(text)) !== null) {
+      found.add(m[2]!.toLowerCase());
+      if (found.size >= 16) break;
+    }
+    return [...found];
+  };
+
   const send = async () => {
     const text = draft.trim();
     if (!text) return;
@@ -421,10 +436,16 @@ export function TopicChatPanel({
     setError(null);
     try {
       const { ciphertext, nonce } = encodeOutgoing(text);
+      const mentions = extractMentions(text);
       const res = await fetch("/api/v1/messages", {
         method: "POST",
         headers,
-        body: JSON.stringify({ topic: topicName, ciphertext, nonce }),
+        body: JSON.stringify({
+          topic: topicName,
+          ciphertext,
+          nonce,
+          ...(mentions.length > 0 ? { mentions } : {}),
+        }),
       });
       if (!res.ok) {
         const body = await res.text().catch(() => "");

packages/api/src/modules/mesh/v1-router.ts

@@ -31,6 +31,7 @@ import {
   mesh,
   meshApiKey,
   meshMember,
+  meshNotification,
   meshTopic,
   meshTopicMember,
   meshTopicMessage,
@@ -56,8 +57,43 @@ const sendMessageSchema = z.object({
   /** base64 nonce. */
   nonce: z.string().min(1),
   priority: z.enum(["now", "next", "low"]).optional().default("next"),
+  /**
+   * Optional list of `@<displayName>` mentions extracted client-side
+   * from the plaintext. Capped at 16 to bound notification fan-out
+   * (anti-spam). Server intersects with the mesh roster — anything
+   * that doesn't resolve to a member is silently dropped.
+   *
+   * Falls back to a server-side regex on the base64 plaintext when
+   * absent (v0.2.0 messages still ship plaintext). After per-topic
+   * encryption lands the regex path stops working and the client
+   * MUST send this array.
+   */
+  mentions: z.array(z.string().min(1).max(64)).max(16).optional(),
 });
 
+/**
+ * Extract `@<token>` mentions from base64-encoded plaintext. Returns
+ * the lowercased display names found in the body, deduped and capped
+ * at 16. Used as the legacy fallback when the client doesn't send a
+ * `mentions` array on POST /messages.
+ */
+function extractMentionsFromBase64(b64: string): string[] {
+  let text: string;
+  try {
+    text = Buffer.from(b64, "base64").toString("utf-8");
+  } catch {
+    return [];
+  }
+  const found = new Set<string>();
+  const re = /(^|[^A-Za-z0-9_-])@([A-Za-z0-9_-]{1,64})(?=$|[^A-Za-z0-9_-])/g;
+  let m: RegExpExecArray | null;
+  while ((m = re.exec(text)) !== null) {
+    found.add(m[2]!.toLowerCase());
+    if (found.size >= 16) break;
+  }
+  return [...found];
+}
+
 const historyQuerySchema = z.object({
   limit: z.coerce.number().int().min(1).max(200).optional().default(50),
   before: z.string().optional(),
@@ -108,13 +144,19 @@ export const v1Router = new Hono<Env>()
       .limit(1);
     if (!ownerMember) return c.json({ error: "no_mesh_member" }, 500);
 
+    // Sender attribution: prefer the apikey's issuing member (so the
+    // dashboard chat user shows up correctly in /v1/peers and as the
+    // notification sender). Fall back to the oldest mesh member for
+    // legacy keys with no issuer.
+    const senderMemberId = key.issuedByMemberId ?? ownerMember.id;
+
     // Persist to history (topic_message) + ephemeral queue (message_queue).
     // Broker's drain loop picks up the queue entry and pushes to live peers.
     const [historyRow] = await db
       .insert(meshTopicMessage)
       .values({
         topicId: topic.id,
-        senderMemberId: ownerMember.id,
+        senderMemberId,
         nonce: body.nonce,
         ciphertext: body.ciphertext,
       })
@@ -124,7 +166,7 @@ export const v1Router = new Hono<Env>()
       .insert(messageQueue)
       .values({
         meshId: key.meshId,
-        senderMemberId: ownerMember.id,
+        senderMemberId,
         targetSpec: "#" + topic.id,
         priority: body.priority,
         nonce: body.nonce,
@@ -132,11 +174,56 @@ export const v1Router = new Hono<Env>()
       })
       .returning({ id: messageQueue.id });
 
+    // Mention fan-out → notification rows. Client-extracted mentions
+    // win when present (post-encryption clients MUST extract and send);
+    // otherwise we regex the base64 plaintext as a transitional fallback.
+    let mentionTokens = body.mentions?.map((s) => s.toLowerCase().replace(/^@/, ""));
+    if (!mentionTokens || mentionTokens.length === 0) {
+      mentionTokens = extractMentionsFromBase64(body.ciphertext);
+    }
+    let notifications = 0;
+    if (historyRow && mentionTokens.length > 0) {
+      const recipients = await db
+        .select({
+          id: meshMember.id,
+          displayName: meshMember.displayName,
+        })
+        .from(meshMember)
+        .where(
+          and(eq(meshMember.meshId, key.meshId), isNull(meshMember.revokedAt)),
+        );
+      const lowerTokens = new Set(mentionTokens);
+      const targets = recipients
+        .filter(
+          (r) =>
+            lowerTokens.has(r.displayName.toLowerCase()) &&
+            r.id !== senderMemberId,
+        )
+        .slice(0, 32); // hard cap on per-message fan-out
+      if (targets.length > 0) {
+        await db
+          .insert(meshNotification)
+          .values(
+            targets.map((t) => ({
+              meshId: key.meshId,
+              topicId: topic.id,
+              messageId: historyRow.id,
+              recipientMemberId: t.id,
+              senderMemberId,
+              kind: "mention",
+            })),
+          )
+          .onConflictDoNothing();
+        notifications = targets.length;
+      }
+    }
+
     return c.json({
       messageId: queueRow?.id ?? null,
       historyId: historyRow?.id ?? null,
       topic: body.topic,
       topicId: topic.id,
+      notifications,
     });
   })
 
@@ -508,13 +595,14 @@ export const v1Router = new Hono<Env>()
     });
   })
 
-  // GET /v1/notifications — recent @-mentions of the viewer across all
+  // GET /v1/notifications — recent @-mentions of the viewer across
-  // topics in the key's mesh. v0.2.0 plaintext-base64 ciphertext lets
+  // all topics in the key's mesh. Reads from mesh.notification, which
-  // us regex match server-side; in v0.3.0 (per-topic encryption) this
+  // is populated at write time by POST /v1/messages and the broker's
-  // moves to a notification table populated at write time.
+  // topic-send handler. Survives the v0.3.0 per-topic encryption cut
+  // (the regex-on-decoded-ciphertext approach won't).
   //
-  // Query: ?since=<ISO> to incrementally fetch only newer mentions
+  // Query: ?since=<ISO> for incremental fetch (polling bells), and
-  // (e.g. for a polling notification bell). Default: last 24h.
+  // ?unread=1 to filter to read_at IS NULL only.
   .get("/notifications", async (c) => {
     const key = c.var.apiKey;
     requireCapability(key, "read");
@@ -535,50 +623,54 @@ export const v1Router = new Hono<Env>()
     if (Number.isNaN(since.getTime())) {
       return c.json({ error: "invalid_since" }, 400);
     }
+    const unreadOnly = c.req.query("unread") === "1";
 
-    // Postgres regex with case-insensitive match + word boundary on
+    const conditions = [
-    // both sides. Decode the base64 ciphertext (plaintext envelope in
+      eq(meshNotification.recipientMemberId, key.issuedByMemberId),
-    // v0.2.0) so we're matching readable text, not the base64 alphabet.
+      eq(meshNotification.meshId, key.meshId),
-    const escaped = me.displayName.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+      gt(meshNotification.createdAt, since),
-    const pattern = `(^|\\s|[^A-Za-z0-9_-])@${escaped}($|[^A-Za-z0-9_-])`;
+    ];
+    if (unreadOnly) conditions.push(isNull(meshNotification.readAt));
 
     const rows = await db
       .select({
         id: meshTopicMessage.id,
+        notificationId: meshNotification.id,
         topicId: meshTopicMessage.topicId,
         topicName: meshTopic.name,
         senderMemberId: meshTopicMessage.senderMemberId,
         senderName: meshMember.displayName,
         senderPubkey: meshMember.peerPubkey,
         ciphertext: meshTopicMessage.ciphertext,
+        kind: meshNotification.kind,
+        readAt: meshNotification.readAt,
         createdAt: meshTopicMessage.createdAt,
       })
-      .from(meshTopicMessage)
+      .from(meshNotification)
-      .innerJoin(meshTopic, eq(meshTopic.id, meshTopicMessage.topicId))
+      .innerJoin(
+        meshTopicMessage,
+        eq(meshTopicMessage.id, meshNotification.messageId),
+      )
+      .innerJoin(meshTopic, eq(meshTopic.id, meshNotification.topicId))
       .innerJoin(
         meshMember,
-        eq(meshMember.id, meshTopicMessage.senderMemberId),
+        eq(meshMember.id, meshNotification.senderMemberId),
-      )
-      .where(
-        and(
-          eq(meshTopic.meshId, key.meshId),
-          isNull(meshTopic.archivedAt),
-          gt(meshTopicMessage.createdAt, since),
-          sql`${meshTopicMessage.senderMemberId} <> ${key.issuedByMemberId}`,
-          sql`convert_from(decode(${meshTopicMessage.ciphertext}, 'base64'), 'UTF8') ~* ${pattern}`,
-        ),
       )
+      .where(and(...conditions))
       .orderBy(desc(meshTopicMessage.createdAt))
       .limit(50);
 
     return c.json({
       notifications: rows.map((r) => ({
         id: r.id,
+        notificationId: r.notificationId,
         topicId: r.topicId,
         topicName: r.topicName,
         senderName: r.senderName,
         senderPubkey: r.senderPubkey,
         ciphertext: r.ciphertext,
+        kind: r.kind,
+        readAt: r.readAt?.toISOString() ?? null,
         createdAt: r.createdAt.toISOString(),
       })),
       since: since.toISOString(),
@@ -586,6 +678,64 @@ export const v1Router = new Hono<Env>()
     });
   })
 
+  // POST /v1/notifications/read — mark notifications read. Body shape:
+  //   { ids: string[] }                — mark these notification ids
+  //   { all: true, before?: ISO }      — mark every unread for this
+  //                                      member up to `before` (or now)
+  // Idempotent. Always 200, even if 0 rows updated.
+  .post(
+    "/notifications/read",
+    validate(
+      "json",
+      z.union([
+        z.object({ ids: z.array(z.string().min(1)).min(1).max(200) }),
+        z.object({ all: z.literal(true), before: z.string().optional() }),
+      ]),
+    ),
+    async (c) => {
+      const key = c.var.apiKey;
+      requireCapability(key, "read");
+      if (!key.issuedByMemberId) {
+        return c.json({ error: "api_key_has_no_issuer" }, 400);
+      }
+
+      const body = c.req.valid("json");
+      const now = new Date();
+
+      if ("ids" in body) {
+        await db
+          .update(meshNotification)
+          .set({ readAt: now })
+          .where(
+            and(
+              eq(meshNotification.recipientMemberId, key.issuedByMemberId),
+              eq(meshNotification.meshId, key.meshId),
+              isNull(meshNotification.readAt),
+              sql`${meshNotification.id} = ANY(${body.ids})`,
+            ),
+          );
+        return c.json({ marked: body.ids.length, readAt: now.toISOString() });
+      }
+
+      const beforeAt = body.before ? new Date(body.before) : now;
+      if (Number.isNaN(beforeAt.getTime())) {
+        return c.json({ error: "invalid_before" }, 400);
+      }
+      await db
+        .update(meshNotification)
+        .set({ readAt: now })
+        .where(
+          and(
+            eq(meshNotification.recipientMemberId, key.issuedByMemberId),
+            eq(meshNotification.meshId, key.meshId),
+            isNull(meshNotification.readAt),
+            sql`${meshNotification.createdAt} <= ${beforeAt}`,
+          ),
+        );
+      return c.json({ marked: "all", before: beforeAt.toISOString() });
+    },
+  )
+
   // GET /v1/peers — connected peers in the key's mesh
   //
   // Sources, deduped by memberId:

packages/db/migrations/0025_notifications.sql

@@ -0,0 +1,80 @@
+-- Notifications — write-time mention fan-out (v0.3.0 phase 1).
+--
+-- Replaces the regex-on-decoded-ciphertext scan in /v1/notifications and
+-- the dashboard MentionsSection. Lets us drop the
+-- `convert_from(decode(ciphertext, 'base64'), 'UTF8') ~* @name` query that
+-- breaks the moment ciphertext stops being base64-of-UTF8 (i.e. the
+-- moment per-topic encryption lands in v0.3.0 phase 2).
+--
+-- One row per (recipient_member, topic_message). Idempotent ON CONFLICT
+-- on the unique pair; if the broker re-fans a message after a crash the
+-- recipient sees one notification, not two.
+--
+-- Server-side mention extraction happens in POST /v1/messages and the
+-- broker's WS message handler. Both extract @-tokens from the body
+-- BEFORE encryption (the only point at which the server can read it),
+-- match against the topic's member roster, and insert a row per match.
+
+CREATE TABLE IF NOT EXISTS "mesh"."notification" (
+  "id" text PRIMARY KEY NOT NULL,
+  "mesh_id" text NOT NULL REFERENCES "mesh"."mesh"("id") ON DELETE CASCADE ON UPDATE CASCADE,
+  "topic_id" text NOT NULL REFERENCES "mesh"."topic"("id") ON DELETE CASCADE ON UPDATE CASCADE,
+  "message_id" text NOT NULL REFERENCES "mesh"."topic_message"("id") ON DELETE CASCADE ON UPDATE CASCADE,
+  "recipient_member_id" text NOT NULL REFERENCES "mesh"."member"("id") ON DELETE CASCADE ON UPDATE CASCADE,
+  "sender_member_id" text NOT NULL REFERENCES "mesh"."member"("id") ON DELETE CASCADE ON UPDATE CASCADE,
+  "kind" text NOT NULL DEFAULT 'mention',
+  "created_at" timestamp DEFAULT now() NOT NULL,
+  "read_at" timestamp
+);
+
+CREATE UNIQUE INDEX IF NOT EXISTS "notification_unique"
+  ON "mesh"."notification" ("message_id", "recipient_member_id");
+
+CREATE INDEX IF NOT EXISTS "notification_by_recipient_unread"
+  ON "mesh"."notification" ("recipient_member_id", "created_at" DESC)
+  WHERE "read_at" IS NULL;
+
+CREATE INDEX IF NOT EXISTS "notification_by_recipient"
+  ON "mesh"."notification" ("recipient_member_id", "created_at" DESC);
+
+CREATE INDEX IF NOT EXISTS "notification_by_mesh"
+  ON "mesh"."notification" ("mesh_id", "created_at" DESC);
+
+-- Backfill existing v0.2.0 messages so the new table has history. Safe
+-- to run multiple times (ON CONFLICT DO NOTHING). The regex matches the
+-- same shape as the in-app autocomplete + render: @-prefixed token with
+-- a non-word boundary on both sides (or string edges).
+--
+-- We skip messages that fail to decode — defensive against any non-base64
+-- ciphertext that may have slipped in via future writers.
+INSERT INTO "mesh"."notification"
+  ("id", "mesh_id", "topic_id", "message_id", "recipient_member_id",
+   "sender_member_id", "kind", "created_at")
+SELECT
+  replace(gen_random_uuid()::text, '-', ''),
+  t."mesh_id",
+  m."topic_id",
+  m."id",
+  recipient."id",
+  m."sender_member_id",
+  'mention',
+  m."created_at"
+FROM "mesh"."topic_message" m
+INNER JOIN "mesh"."topic" t ON t."id" = m."topic_id"
+INNER JOIN "mesh"."member" recipient
+  ON recipient."mesh_id" = t."mesh_id"
+  AND recipient."revoked_at" IS NULL
+  AND recipient."id" <> m."sender_member_id"
+WHERE
+  -- Only scan messages that look like base64-of-UTF8. Defensive guard
+  -- against a future writer storing binary ciphertext — convert_from
+  -- would otherwise raise and abort the whole migration.
+  m."ciphertext" ~ '^[A-Za-z0-9+/=]+$'
+  AND length(m."ciphertext") > 0
+  AND length(m."ciphertext") % 4 = 0
+  AND convert_from(decode(m."ciphertext", 'base64'), 'UTF8') ~* (
+    '(^|\s|[^A-Za-z0-9_-])@'
+    || regexp_replace(recipient."display_name", '([.*+?^${}()|\[\]\\])', '\\\1', 'g')
+    || '($|[^A-Za-z0-9_-])'
+  )
+ON CONFLICT ("message_id", "recipient_member_id") DO NOTHING;

packages/db/src/schema/mesh.ts

@@ -1484,6 +1484,89 @@ export const insertMeshTopicMessageSchema =
 export type SelectMeshTopicMessage = typeof meshTopicMessage.$inferSelect;
 export type InsertMeshTopicMessage = typeof meshTopicMessage.$inferInsert;
 
+/**
+ * Per-recipient notifications. v0.3.0 phase 1: server-side mention
+ * extraction at write time replaces the regex-on-decoded-ciphertext
+ * scan in /v1/notifications. Fanned out at POST /v1/messages and the
+ * broker's WS topic_send handler — one row per (recipient, message).
+ *
+ * `kind` is open-ended ("mention" today; future kinds: "reply",
+ * "task_assigned", etc.) so we can extend without a migration.
+ */
+export const meshNotification = meshSchema.table(
+  "notification",
+  {
+    id: text().primaryKey().notNull().$defaultFn(generateId),
+    meshId: text()
+      .references(() => mesh.id, {
+        onDelete: "cascade",
+        onUpdate: "cascade",
+      })
+      .notNull(),
+    topicId: text()
+      .references(() => meshTopic.id, {
+        onDelete: "cascade",
+        onUpdate: "cascade",
+      })
+      .notNull(),
+    messageId: text()
+      .references(() => meshTopicMessage.id, {
+        onDelete: "cascade",
+        onUpdate: "cascade",
+      })
+      .notNull(),
+    recipientMemberId: text()
+      .references(() => meshMember.id, {
+        onDelete: "cascade",
+        onUpdate: "cascade",
+      })
+      .notNull(),
+    senderMemberId: text()
+      .references(() => meshMember.id, {
+        onDelete: "cascade",
+        onUpdate: "cascade",
+      })
+      .notNull(),
+    kind: text().notNull().default("mention"),
+    createdAt: timestamp().defaultNow().notNull(),
+    readAt: timestamp(),
+  },
+  (t) => [
+    uniqueIndex("notification_unique").on(t.messageId, t.recipientMemberId),
+    index("notification_by_recipient").on(t.recipientMemberId, t.createdAt),
+    index("notification_by_mesh").on(t.meshId, t.createdAt),
+  ],
+);
+
+export const meshNotificationRelations = relations(
+  meshNotification,
+  ({ one }) => ({
+    topic: one(meshTopic, {
+      fields: [meshNotification.topicId],
+      references: [meshTopic.id],
+    }),
+    message: one(meshTopicMessage, {
+      fields: [meshNotification.messageId],
+      references: [meshTopicMessage.id],
+    }),
+    recipient: one(meshMember, {
+      fields: [meshNotification.recipientMemberId],
+      references: [meshMember.id],
+    }),
+    sender: one(meshMember, {
+      fields: [meshNotification.senderMemberId],
+      references: [meshMember.id],
+    }),
+  }),
+);
+
+export const selectMeshNotificationSchema =
+  createSelectSchema(meshNotification);
+export const insertMeshNotificationSchema =
+  createInsertSchema(meshNotification);
+export type SelectMeshNotification = typeof meshNotification.$inferSelect;
+export type InsertMeshNotification = typeof meshNotification.$inferInsert;
+
 /* ────────────────────────────────────────────────────────────────────────
  * API keys (v0.2.0) — REST + external WS auth.
  *