Email notifications: settings UI + mail adapter

- Add VITE_EMAIL_NOTIFICATION_SERVER env var
- Extend notificationSettings with email, emailFrequency, emailAddress
- Add emailNotificationState store in push/adapters/common.ts
- New src/app/mail/index.ts with MailNotifications class:
  register/unregister with mailship via NIP-98 auth,
  publish kind 30390 NIP-9a subscription events
- Wired into alerts settings save handler
- Email Digest Settings card in alerts UI

src/app/env.ts

@@ -9,6 +9,8 @@ export const PUSH_SERVER = import.meta.env.VITE_PUSH_SERVER
 
 export const PUSH_BRIDGE = normalizeRelayUrl(import.meta.env.VITE_PUSH_BRIDGE)
 
+export const EMAIL_NOTIFICATION_SERVER = import.meta.env.VITE_EMAIL_NOTIFICATION_SERVER
+
 export const ENABLE_ZAPS = Capacitor.getPlatform() != "ios"
 
 export const SIGNER_RELAYS = fromCsv(import.meta.env.VITE_SIGNER_RELAYS).map(normalizeRelayUrl)

src/app/mail/index.ts

@@ -0,0 +1,162 @@
+import {hash, maybe} from "@welshman/lib"
+import type {Filter} from "@welshman/util"
+import {Address, DELETE, makeEvent, makeHttpAuth, makeHttpAuthHeader} from "@welshman/util"
+import {Relays, User} from "@welshman/app"
+import {buildUrl} from "@lib/util"
+import {app, thunks} from "@app/core"
+import {device} from "@app/device"
+import {EMAIL_NOTIFICATION_SERVER, PUSH_BRIDGE} from "@app/env"
+import {emailNotificationState, syncRelaySubscriptions} from "@app/push/adapters/common"
+
+export class MailNotifications {
+  _controller = maybe<AbortController>()
+
+  async register(email: string, frequency: string) {
+    const $app = app.get()
+    const $pubkey = User.require($app).pubkey
+    const $signer = $app.signer
+
+    if (!$signer) throw new Error("No signer available")
+
+    const authEvent = await $signer.sign(await makeHttpAuth(EMAIL_NOTIFICATION_SERVER, "POST"))
+    const authHeader = makeHttpAuthHeader(authEvent)
+
+    const res = await fetch(buildUrl(EMAIL_NOTIFICATION_SERVER, "subscription", "email"), {
+      method: "POST",
+      body: JSON.stringify({email, frequency, pubkey: $pubkey}),
+      headers: {Authorization: authHeader, "Content-Type": "application/json"},
+    })
+
+    if (!res.ok) throw new Error(`Registration failed: ${await res.text()}`)
+
+    const {key, callback} = await res.json()
+    emailNotificationState.set({key, callback, email, frequency})
+  }
+
+  async unregister() {
+    const {key} = emailNotificationState.get()
+    if (!key) return
+
+    const $app = app.get()
+    const $signer = $app.signer
+    if (!$signer) return
+
+    try {
+      const authEvent = await $signer.sign(await makeHttpAuth(EMAIL_NOTIFICATION_SERVER, "DELETE"))
+      const authHeader = makeHttpAuthHeader(authEvent)
+
+      await fetch(buildUrl(EMAIL_NOTIFICATION_SERVER, "subscription", key), {
+        method: "DELETE",
+        headers: {Authorization: authHeader},
+      })
+    } catch {
+      // Best effort
+    }
+
+    emailNotificationState.set({})
+  }
+
+  async enable() {
+    if (this._controller) return
+
+    const {email, frequency} = emailNotificationState.get()
+
+    if (!EMAIL_NOTIFICATION_SERVER) {
+      console.warn("Email notification server not configured")
+      return
+    }
+
+    this._controller = new AbortController()
+
+    // Register if we don't have a subscription yet
+    if (!emailNotificationState.get().callback && email && frequency) {
+      await this.register(email, frequency)
+    }
+
+    // Sync kind 30390 subscriptions using the same filters as push
+    syncRelaySubscriptions(
+      this._controller.signal,
+      async (url: string, key: string, filters: Filter[], ignore: Filter[]) => {
+        const {callback} = emailNotificationState.get()
+        if (!callback) return
+
+        if (filters.length > 0) {
+          await this._syncRelay(url, key, filters, ignore)
+        } else {
+          await this._unsyncRelay(url, key)
+        }
+      },
+    )
+  }
+
+  async disable() {
+    this._controller?.abort()
+    this._controller = undefined
+
+    await this.unregister()
+  }
+
+  _getSubscriptionIdentifier = (relay: string, key: string) =>
+    String(hash(relay + key + device.get() + "email"))
+
+  _getPushUrl = async (url: string) => {
+    for (const candidate of [url, PUSH_BRIDGE]) {
+      const relay = await app.get().use(Relays).load(candidate)
+
+      if (relay?.hasNip("9a")) {
+        return candidate
+      }
+    }
+  }
+
+  _syncRelay = async (relay: string, key: string, filters: Filter[], ignore: Filter[] = []) => {
+    const {callback} = emailNotificationState.get()
+    if (!callback) return
+
+    const url = await this._getPushUrl(relay)
+    if (!url) {
+      console.warn(`Failed to subscribe ${relay} to email notifications: unsupported`)
+      return
+    }
+
+    const identifier = this._getSubscriptionIdentifier(relay, key)
+
+    const thunk = thunks.get().publish({
+      relays: [url],
+      event: makeEvent(30390, {
+        tags: [
+          ["d", identifier],
+          ["relay", relay],
+          ["callback", callback],
+          ...ignore.map(f => ["ignore", JSON.stringify(f)]),
+          ...filters.map(f => ["filter", JSON.stringify(f)]),
+        ],
+      }),
+    })
+
+    const error = await thunk.waitForError()
+    if (error) {
+      console.warn(`Failed to subscribe ${relay} to email notifications:`, error)
+    }
+  }
+
+  _unsyncRelay = async (relay: string, key: string) => {
+    const url = await this._getPushUrl(relay)
+    if (!url) return
+
+    const $pubkey = User.require(app.get()).pubkey
+    const identifier = this._getSubscriptionIdentifier(relay, key)
+    const address = new Address(30390, $pubkey, identifier).toString()
+    const event = makeEvent(DELETE, {tags: [["a", address]]})
+    const error = await thunks
+      .get()
+      .publish({relays: [url], event})
+      .waitForError()
+
+    if (error) {
+      console.warn(`Failed to unsubscribe ${relay} from email notifications:`, error)
+    }
+  }
+}
+
+export const Mail = new MailNotifications()

src/app/push/adapters/common.ts

@@ -40,6 +40,15 @@ export type PushState = {
 
 export const pushState = withGetter(writable<PushState>({}))
 
+export type EmailNotificationState = {
+  key?: string
+  callback?: string
+  email?: string
+  frequency?: string
+}
+
+export const emailNotificationState = withGetter(writable<EmailNotificationState>({}))
+
 export interface IPushAdapter {
   request: (prompt?: boolean) => Promise<string>
   disable: () => Promise<void>

src/app/settings.ts

@@ -99,6 +99,9 @@ export const notificationSettings = withGetter(
     spaces: true,
     mentions: true,
     messages: true,
+    email: false,
+    emailFrequency: "daily",
+    emailAddress: "",
   }),
 )
 

src/routes/settings/alerts/+page.svelte

@@ -14,6 +14,7 @@
   import {pushToast} from "@app/toast"
   import {clearBadges} from "@app/notifications"
   import {Push} from "@app/push"
+  import {Mail} from "@app/mail"
   import {notificationSettings} from "@app/settings"
 
   const reset = () => {
@@ -45,6 +46,19 @@
         }
       }
 
+      // Handle email notification registration
+      if (settings.email && settings.emailAddress) {
+        try {
+          await Mail.register(settings.emailAddress, settings.emailFrequency)
+          await Mail.enable()
+        } catch (e) {
+          console.warn("Failed to enable email notifications:", e)
+          pushToast({theme: "error", message: "Failed to enable email notifications."})
+        }
+      } else if (!settings.email) {
+        await Mail.disable()
+      }
+
       notificationSettings.set(settings)
 
       pushToast({message: "Your settings have been saved!"})
@@ -127,6 +141,42 @@
         {/snippet}
       </FieldInline>
     </div>
+    <div class="card bg-surface flex flex-col gap-4 shadow-md">
+      <strong class="text-lg">Email Digest Settings</strong>
+      <FieldInline>
+        {#snippet label()}
+          <p>Receive email digest of missed activity</p>
+        {/snippet}
+        {#snippet input()}
+          <ToggleInput bind:checked={settings.email} />
+        {/snippet}
+      </FieldInline>
+      {#if settings.email}
+        <FieldInline>
+          {#snippet label()}
+            <p>Email address</p>
+          {/snippet}
+          {#snippet input()}
+            <input
+              type="email"
+              class="input input-bordered w-full"
+              bind:value={settings.emailAddress}
+              placeholder="you@example.com" />
+          {/snippet}
+        </FieldInline>
+        <FieldInline>
+          {#snippet label()}
+            <p>Frequency</p>
+          {/snippet}
+          {#snippet input()}
+            <select class="select select-bordered" bind:value={settings.emailFrequency}>
+              <option value="daily">Daily</option>
+              <option value="weekly">Weekly</option>
+            </select>
+          {/snippet}
+        </FieldInline>
+      {/if}
+    </div>
     <div class="card sticky -bottom-3 shadow-md flex flex-row items-center justify-between gap-4">
       <Button class="button button-neutral" onclick={reset} disabled={loading}
         >Discard Changes</Button>