feat(nostr-feed): Add link aggregator core data model (Phase 1)

Implement Reddit-style link aggregator foundation using NIP-72 (Moderated
Communities) and NIP-22 (Comments) specifications.

New files:
- types/submission.ts: Complete type definitions for submissions, voting,
  communities, link previews, and ranking algorithms
- services/SubmissionService.ts: Core service for kind 1111 submission
  events with parsing, creation, voting, and comment threading
- services/LinkPreviewService.ts: Open Graph metadata fetching with
  caching, CORS proxy support, and oEmbed fallbacks
- composables/useSubmissions.ts: Vue composable for reactive submission
  state management
- LINK_AGGREGATOR_PLAN.md: Implementation roadmap

Features:
- Three post types: link, media, self (text)
- NIP-22 compliant community-scoped posts
- NIP-92 media attachments with imeta tags
- Hot/Top/New/Controversial ranking algorithms
- Threaded comment support
- Upvote/downvote via NIP-25 reactions

🤖 Generated with [Claude Code](https://claude.ai/code)

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

src/core/di-container.ts

@@ -137,6 +137,11 @@ export const SERVICE_TOKENS = {
   PROFILE_SERVICE: Symbol('profileService'),
   REACTION_SERVICE: Symbol('reactionService'),
 
+  // Link aggregator services
+  SUBMISSION_SERVICE: Symbol('submissionService'),
+  LINK_PREVIEW_SERVICE: Symbol('linkPreviewService'),
+  COMMUNITY_SERVICE: Symbol('communityService'),
+
   // Nostr metadata services
   NOSTR_METADATA_SERVICE: Symbol('nostrMetadataService'),
 

src/modules/nostr-feed/LINK_AGGREGATOR_PLAN.md

@@ -0,0 +1,168 @@
+# Link Aggregator Implementation Plan
+
+## Overview
+
+Transform the nostr-feed module into a Reddit-style link aggregator with support for:
+- **Link posts** - External URLs with Open Graph previews
+- **Media posts** - Images/videos with inline display
+- **Self posts** - Text/markdown content
+
+## NIP Compliance
+
+| NIP | Purpose | Usage |
+|-----|---------|-------|
+| NIP-72 | Moderated Communities | Community definitions (kind 34550), approvals (kind 4550) |
+| NIP-22 | Comments | Community posts (kind 1111) with scoped threading |
+| NIP-92 | Media Attachments | `imeta` tags for media metadata |
+| NIP-94 | File Metadata | Reference for media fields |
+| NIP-25 | Reactions | Upvote (`+`) / Downvote (`-`) |
+| NIP-10 | Reply Threading | Fallback for kind 1 compatibility |
+
+## Event Structure
+
+### Submission (kind 1111)
+
+```jsonc
+{
+  "kind": 1111,
+  "content": "<self-post body or link description>",
+  "tags": [
+    // Community scope (NIP-72 + NIP-22)
+    ["A", "34550:<community-pubkey>:<community-d>", "<relay>"],
+    ["a", "34550:<community-pubkey>:<community-d>", "<relay>"],
+    ["K", "34550"],
+    ["k", "34550"],
+    ["P", "<community-pubkey>"],
+    ["p", "<community-pubkey>"],
+
+    // Submission metadata
+    ["title", "<post title>"],
+    ["post-type", "link|media|self"],
+
+    // Link post fields
+    ["r", "<url>"],
+    ["preview-title", "<og:title>"],
+    ["preview-description", "<og:description>"],
+    ["preview-image", "<og:image>"],
+    ["preview-site-name", "<og:site_name>"],
+
+    // Media post fields (NIP-92)
+    ["imeta", "url <url>", "m <mime>", "dim <WxH>", "blurhash <hash>", "alt <desc>"],
+
+    // Common
+    ["t", "<hashtag>"],
+    ["nsfw", "true|false"]
+  ]
+}
+```
+
+### Comment on Submission (kind 1111)
+
+```jsonc
+{
+  "kind": 1111,
+  "content": "<comment text>",
+  "tags": [
+    // Root scope (the community)
+    ["A", "34550:<community-pubkey>:<community-d>", "<relay>"],
+    ["K", "34550"],
+    ["P", "<community-pubkey>"],
+
+    // Parent (the submission or parent comment)
+    ["e", "<parent-event-id>", "<relay>", "<parent-pubkey>"],
+    ["k", "1111"],
+    ["p", "<parent-pubkey>"]
+  ]
+}
+```
+
+## Implementation Phases
+
+### Phase 1: Core Data Model (Current)
+- [x] Create feature branch
+- [x] Document plan
+- [ ] Create `types/submission.ts` - Type definitions
+- [ ] Create `SubmissionService.ts` - Submission CRUD
+- [ ] Create `LinkPreviewService.ts` - OG tag fetching
+- [ ] Extend `FeedService.ts` - Handle kind 1111
+
+### Phase 2: Post Creation
+- [ ] Create `SubmitComposer.vue` - Multi-type composer
+- [ ] Add link preview on URL paste
+- [ ] Integrate with pictrs for media upload
+- [ ] Add NSFW toggle
+
+### Phase 3: Feed Display
+- [ ] Create `SubmissionCard.vue` - Link aggregator card
+- [ ] Create `VoteButtons.vue` - Up/down voting
+- [ ] Add feed sorting (hot, new, top, controversial)
+- [ ] Add score calculation
+
+### Phase 4: Detail View
+- [ ] Create `SubmissionDetail.vue` - Full post view
+- [ ] Integrate `ThreadedPost.vue` for comments
+- [ ] Add comment sorting
+
+### Phase 5: Communities (Future)
+- [ ] Create `CommunityService.ts`
+- [ ] Create community browser
+- [ ] Add moderation queue
+
+## Ranking Algorithms
+
+### Hot Rank (Lemmy-style)
+```typescript
+function hotRank(score: number, createdAt: Date): number {
+  const order = Math.log10(Math.max(Math.abs(score), 1))
+  const sign = score > 0 ? 1 : score < 0 ? -1 : 0
+  const seconds = (createdAt.getTime() - EPOCH.getTime()) / 1000
+  return sign * order + seconds / 45000
+}
+```
+
+### Controversy Rank
+```typescript
+function controversyRank(upvotes: number, downvotes: number): number {
+  const total = upvotes + downvotes
+  if (total === 0) return 0
+  const magnitude = Math.pow(total, 0.8)
+  const balance = total > 0 ? Math.min(upvotes, downvotes) / Math.max(upvotes, downvotes) : 0
+  return magnitude * balance
+}
+```
+
+## File Structure
+
+```
+src/modules/nostr-feed/
+├── types/
+│   └── submission.ts         # NEW
+├── services/
+│   ├── FeedService.ts        # MODIFY
+│   ├── SubmissionService.ts  # NEW
+│   ├── LinkPreviewService.ts # NEW
+│   ├── CommunityService.ts   # NEW (Phase 5)
+│   ├── ProfileService.ts     # EXISTING
+│   └── ReactionService.ts    # EXISTING (enhance for up/down)
+├── components/
+│   ├── SubmissionCard.vue    # NEW (Phase 3)
+│   ├── SubmitComposer.vue    # NEW (Phase 2)
+│   ├── SubmissionDetail.vue  # NEW (Phase 4)
+│   ├── VoteButtons.vue       # NEW (Phase 3)
+│   ├── ThreadedPost.vue      # EXISTING (reuse)
+│   ├── NostrFeed.vue         # EXISTING (modify)
+│   └── NoteComposer.vue      # EXISTING
+├── composables/
+│   ├── useSubmissions.ts     # NEW
+│   ├── useCommunities.ts     # NEW (Phase 5)
+│   ├── useFeed.ts            # EXISTING
+│   └── useReactions.ts       # EXISTING
+└── config/
+    └── content-filters.ts    # MODIFY
+```
+
+## Migration Strategy
+
+1. **Backwards compatible** - Continue supporting kind 1 notes
+2. **Gradual adoption** - Add kind 1111 alongside existing
+3. **Feature flag** - Toggle between classic feed and link aggregator view

src/modules/nostr-feed/composables/useSubmissions.ts

@@ -0,0 +1,309 @@
+/**
+ * useSubmissions Composable
+ *
+ * Provides reactive access to the SubmissionService for Reddit-style submissions.
+ */
+
+import { computed, ref, onMounted, onUnmounted, watch } from 'vue'
+import { tryInjectService, SERVICE_TOKENS } from '@/core/di-container'
+import type { SubmissionService } from '../services/SubmissionService'
+import type { LinkPreviewService } from '../services/LinkPreviewService'
+import type {
+  SubmissionWithMeta,
+  SubmissionForm,
+  SubmissionFeedConfig,
+  SubmissionComment,
+  SortType,
+  TimeRange,
+  LinkPreview
+} from '../types/submission'
+
+// ============================================================================
+// Types
+// ============================================================================
+
+export interface UseSubmissionsOptions {
+  /** Auto-subscribe on mount */
+  autoSubscribe?: boolean
+  /** Feed configuration */
+  config?: Partial<SubmissionFeedConfig>
+}
+
+export interface UseSubmissionsReturn {
+  // State
+  submissions: ReturnType<typeof computed<SubmissionWithMeta[]>>
+  isLoading: ReturnType<typeof computed<boolean>>
+  error: ReturnType<typeof computed<string | null>>
+
+  // Sorting
+  currentSort: ReturnType<typeof ref<SortType>>
+  currentTimeRange: ReturnType<typeof ref<TimeRange>>
+
+  // Actions
+  subscribe: (config?: Partial<SubmissionFeedConfig>) => Promise<void>
+  unsubscribe: () => Promise<void>
+  refresh: () => Promise<void>
+  createSubmission: (form: SubmissionForm) => Promise<string>
+  upvote: (submissionId: string) => Promise<void>
+  downvote: (submissionId: string) => Promise<void>
+  setSort: (sort: SortType, timeRange?: TimeRange) => void
+
+  // Getters
+  getSubmission: (id: string) => SubmissionWithMeta | undefined
+  getComments: (submissionId: string) => SubmissionComment[]
+  getThreadedComments: (submissionId: string) => SubmissionComment[]
+
+  // Link preview
+  fetchLinkPreview: (url: string) => Promise<LinkPreview>
+  isPreviewLoading: (url: string) => boolean
+}
+
+// ============================================================================
+// Composable
+// ============================================================================
+
+export function useSubmissions(options: UseSubmissionsOptions = {}): UseSubmissionsReturn {
+  const {
+    autoSubscribe = true,
+    config: initialConfig = {}
+  } = options
+
+  // Inject services
+  const submissionService = tryInjectService<SubmissionService>(SERVICE_TOKENS.SUBMISSION_SERVICE)
+  const linkPreviewService = tryInjectService<LinkPreviewService>(SERVICE_TOKENS.LINK_PREVIEW_SERVICE)
+
+  // Local state
+  const currentSort = ref<SortType>('hot')
+  const currentTimeRange = ref<TimeRange>('day')
+
+  // Default feed config
+  const defaultConfig: SubmissionFeedConfig = {
+    sort: 'hot',
+    timeRange: 'day',
+    includeNsfw: false,
+    limit: 50,
+    ...initialConfig
+  }
+
+  // Computed values from service
+  const submissions = computed(() => {
+    if (!submissionService) return []
+    return submissionService.getSortedSubmissions(currentSort.value)
+  })
+
+  const isLoading = computed(() => submissionService?.isLoading.value ?? false)
+  const error = computed(() => submissionService?.error.value ?? null)
+
+  // ============================================================================
+  // Actions
+  // ============================================================================
+
+  /**
+   * Subscribe to submissions feed
+   */
+  async function subscribe(config?: Partial<SubmissionFeedConfig>): Promise<void> {
+    if (!submissionService) {
+      console.warn('SubmissionService not available')
+      return
+    }
+
+    const feedConfig: SubmissionFeedConfig = {
+      ...defaultConfig,
+      ...config,
+      sort: currentSort.value,
+      timeRange: currentTimeRange.value
+    }
+
+    await submissionService.subscribe(feedConfig)
+  }
+
+  /**
+   * Unsubscribe from feed
+   */
+  async function unsubscribe(): Promise<void> {
+    await submissionService?.unsubscribe()
+  }
+
+  /**
+   * Refresh the feed
+   */
+  async function refresh(): Promise<void> {
+    submissionService?.clear()
+    await subscribe()
+  }
+
+  /**
+   * Create a new submission
+   */
+  async function createSubmission(form: SubmissionForm): Promise<string> {
+    if (!submissionService) {
+      throw new Error('SubmissionService not available')
+    }
+    return submissionService.createSubmission(form)
+  }
+
+  /**
+   * Upvote a submission
+   */
+  async function upvote(submissionId: string): Promise<void> {
+    if (!submissionService) {
+      throw new Error('SubmissionService not available')
+    }
+    await submissionService.upvote(submissionId)
+  }
+
+  /**
+   * Downvote a submission
+   */
+  async function downvote(submissionId: string): Promise<void> {
+    if (!submissionService) {
+      throw new Error('SubmissionService not available')
+    }
+    await submissionService.downvote(submissionId)
+  }
+
+  /**
+   * Change sort order
+   */
+  function setSort(sort: SortType, timeRange?: TimeRange): void {
+    currentSort.value = sort
+    if (timeRange) {
+      currentTimeRange.value = timeRange
+    }
+  }
+
+  // ============================================================================
+  // Getters
+  // ============================================================================
+
+  /**
+   * Get a single submission by ID
+   */
+  function getSubmission(id: string): SubmissionWithMeta | undefined {
+    return submissionService?.getSubmission(id)
+  }
+
+  /**
+   * Get comments for a submission
+   */
+  function getComments(submissionId: string): SubmissionComment[] {
+    return submissionService?.getComments(submissionId) ?? []
+  }
+
+  /**
+   * Get threaded comments for a submission
+   */
+  function getThreadedComments(submissionId: string): SubmissionComment[] {
+    return submissionService?.getThreadedComments(submissionId) ?? []
+  }
+
+  // ============================================================================
+  // Link Preview
+  // ============================================================================
+
+  /**
+   * Fetch link preview for a URL
+   */
+  async function fetchLinkPreview(url: string): Promise<LinkPreview> {
+    if (!linkPreviewService) {
+      return {
+        url,
+        domain: new URL(url).hostname.replace(/^www\./, '')
+      }
+    }
+    return linkPreviewService.fetchPreview(url)
+  }
+
+  /**
+   * Check if preview is loading
+   */
+  function isPreviewLoading(url: string): boolean {
+    return linkPreviewService?.isLoading(url) ?? false
+  }
+
+  // ============================================================================
+  // Lifecycle
+  // ============================================================================
+
+  // Watch for sort changes and re-sort
+  watch([currentSort, currentTimeRange], async () => {
+    // Re-subscribe with new sort if needed for time-based filtering
+    if (currentSort.value === 'top') {
+      await subscribe()
+    }
+  })
+
+  // Auto-subscribe on mount
+  onMounted(() => {
+    if (autoSubscribe) {
+      subscribe()
+    }
+  })
+
+  // Cleanup on unmount
+  onUnmounted(() => {
+    unsubscribe()
+  })
+
+  // ============================================================================
+  // Return
+  // ============================================================================
+
+  return {
+    // State
+    submissions,
+    isLoading,
+    error,
+
+    // Sorting
+    currentSort,
+    currentTimeRange,
+
+    // Actions
+    subscribe,
+    unsubscribe,
+    refresh,
+    createSubmission,
+    upvote,
+    downvote,
+    setSort,
+
+    // Getters
+    getSubmission,
+    getComments,
+    getThreadedComments,
+
+    // Link preview
+    fetchLinkPreview,
+    isPreviewLoading
+  }
+}
+
+// ============================================================================
+// Single Submission Hook
+// ============================================================================
+
+/**
+ * Hook for working with a single submission
+ */
+export function useSubmission(submissionId: string) {
+  const submissionService = tryInjectService<SubmissionService>(SERVICE_TOKENS.SUBMISSION_SERVICE)
+
+  const submission = computed(() => submissionService?.getSubmission(submissionId))
+  const comments = computed(() => submissionService?.getThreadedComments(submissionId) ?? [])
+
+  async function upvote(): Promise<void> {
+    await submissionService?.upvote(submissionId)
+  }
+
+  async function downvote(): Promise<void> {
+    await submissionService?.downvote(submissionId)
+  }
+
+  return {
+    submission,
+    comments,
+    upvote,
+    downvote
+  }
+}

src/modules/nostr-feed/index.ts

@@ -6,6 +6,8 @@ import { useFeed } from './composables/useFeed'
 import { FeedService } from './services/FeedService'
 import { ProfileService } from './services/ProfileService'
 import { ReactionService } from './services/ReactionService'
+import { SubmissionService } from './services/SubmissionService'
+import { LinkPreviewService } from './services/LinkPreviewService'
 
 /**
  * Nostr Feed Module Plugin
@@ -23,10 +25,14 @@ export const nostrFeedModule: ModulePlugin = {
     const feedService = new FeedService()
     const profileService = new ProfileService()
     const reactionService = new ReactionService()
+    const submissionService = new SubmissionService()
+    const linkPreviewService = new LinkPreviewService()
 
     container.provide(SERVICE_TOKENS.FEED_SERVICE, feedService)
     container.provide(SERVICE_TOKENS.PROFILE_SERVICE, profileService)
     container.provide(SERVICE_TOKENS.REACTION_SERVICE, reactionService)
+    container.provide(SERVICE_TOKENS.SUBMISSION_SERVICE, submissionService)
+    container.provide(SERVICE_TOKENS.LINK_PREVIEW_SERVICE, linkPreviewService)
     console.log('nostr-feed module: Services registered in DI container')
 
     // Initialize services
@@ -43,6 +49,14 @@ export const nostrFeedModule: ModulePlugin = {
       reactionService.initialize({
         waitForDependencies: true,
         maxRetries: 3
+      }),
+      submissionService.initialize({
+        waitForDependencies: true,
+        maxRetries: 3
+      }),
+      linkPreviewService.initialize({
+        waitForDependencies: true,
+        maxRetries: 3
       })
     ])
     console.log('nostr-feed module: Services initialized')

src/modules/nostr-feed/services/LinkPreviewService.ts

@@ -0,0 +1,552 @@
+/**
+ * LinkPreviewService
+ *
+ * Fetches Open Graph and meta tags from URLs to generate link previews.
+ * Used when creating link submissions to embed preview data.
+ */
+
+import { ref, reactive } from 'vue'
+import { BaseService } from '@/core/base/BaseService'
+import type { LinkPreview } from '../types/submission'
+import { extractDomain } from '../types/submission'
+
+// ============================================================================
+// Types
+// ============================================================================
+
+interface CacheEntry {
+  preview: LinkPreview
+  timestamp: number
+}
+
+// ============================================================================
+// Service Definition
+// ============================================================================
+
+export class LinkPreviewService extends BaseService {
+  protected readonly metadata = {
+    name: 'LinkPreviewService',
+    version: '1.0.0',
+    dependencies: []
+  }
+
+  // Cache for previews (URL -> preview)
+  private cache = reactive(new Map<string, CacheEntry>())
+
+  // Cache TTL (15 minutes)
+  private readonly CACHE_TTL = 15 * 60 * 1000
+
+  // Loading state per URL
+  private _loading = reactive(new Map<string, boolean>())
+
+  // Error state per URL
+  private _errors = reactive(new Map<string, string>())
+
+  // CORS proxy URL (configurable)
+  private proxyUrl = ''
+
+  // ============================================================================
+  // Lifecycle
+  // ============================================================================
+
+  protected async onInitialize(): Promise<void> {
+    console.log('LinkPreviewService: Initializing...')
+
+    // Try to get proxy URL from environment
+    this.proxyUrl = import.meta.env.VITE_CORS_PROXY_URL || ''
+
+    // Clean expired cache entries periodically
+    setInterval(() => this.cleanCache(), this.CACHE_TTL)
+
+    console.log('LinkPreviewService: Initialization complete')
+  }
+
+  protected async onDispose(): Promise<void> {
+    this.cache.clear()
+    this._loading.clear()
+    this._errors.clear()
+  }
+
+  // ============================================================================
+  // Public API
+  // ============================================================================
+
+  /**
+   * Fetch link preview for a URL
+   */
+  async fetchPreview(url: string): Promise<LinkPreview> {
+    // Normalize URL
+    const normalizedUrl = this.normalizeUrl(url)
+
+    // Check cache
+    const cached = this.getCachedPreview(normalizedUrl)
+    if (cached) {
+      return cached
+    }
+
+    // Check if already loading
+    if (this._loading.get(normalizedUrl)) {
+      // Wait for existing request
+      return this.waitForPreview(normalizedUrl)
+    }
+
+    // Mark as loading
+    this._loading.set(normalizedUrl, true)
+    this._errors.delete(normalizedUrl)
+
+    try {
+      const preview = await this.doFetch(normalizedUrl)
+
+      // Cache the result
+      this.cache.set(normalizedUrl, {
+        preview,
+        timestamp: Date.now()
+      })
+
+      return preview
+
+    } catch (error) {
+      const message = error instanceof Error ? error.message : 'Failed to fetch preview'
+      this._errors.set(normalizedUrl, message)
+
+      // Return minimal preview on error
+      return {
+        url: normalizedUrl,
+        domain: extractDomain(normalizedUrl)
+      }
+
+    } finally {
+      this._loading.set(normalizedUrl, false)
+    }
+  }
+
+  /**
+   * Get cached preview if available and not expired
+   */
+  getCachedPreview(url: string): LinkPreview | null {
+    const cached = this.cache.get(url)
+    if (!cached) return null
+
+    // Check if expired
+    if (Date.now() - cached.timestamp > this.CACHE_TTL) {
+      this.cache.delete(url)
+      return null
+    }
+
+    return cached.preview
+  }
+
+  /**
+   * Check if URL is currently loading
+   */
+  isLoading(url: string): boolean {
+    return this._loading.get(url) || false
+  }
+
+  /**
+   * Get error for URL
+   */
+  getError(url: string): string | null {
+    return this._errors.get(url) || null
+  }
+
+  /**
+   * Clear cache for a specific URL or all
+   */
+  clearCache(url?: string): void {
+    if (url) {
+      this.cache.delete(url)
+    } else {
+      this.cache.clear()
+    }
+  }
+
+  // ============================================================================
+  // Fetching
+  // ============================================================================
+
+  /**
+   * Perform the actual fetch
+   */
+  private async doFetch(url: string): Promise<LinkPreview> {
+    // Try different methods in order of preference
+
+    // 1. Try direct fetch (works for same-origin or CORS-enabled sites)
+    try {
+      return await this.fetchDirect(url)
+    } catch (directError) {
+      this.debug('Direct fetch failed:', directError)
+    }
+
+    // 2. Try CORS proxy if configured
+    if (this.proxyUrl) {
+      try {
+        return await this.fetchViaProxy(url)
+      } catch (proxyError) {
+        this.debug('Proxy fetch failed:', proxyError)
+      }
+    }
+
+    // 3. Try oEmbed for supported sites
+    try {
+      return await this.fetchOembed(url)
+    } catch (oembedError) {
+      this.debug('oEmbed fetch failed:', oembedError)
+    }
+
+    // 4. Return basic preview with just the domain
+    return {
+      url,
+      domain: extractDomain(url)
+    }
+  }
+
+  /**
+   * Direct fetch (may fail due to CORS)
+   */
+  private async fetchDirect(url: string): Promise<LinkPreview> {
+    const response = await fetch(url, {
+      method: 'GET',
+      headers: {
+        'Accept': 'text/html'
+      }
+    })
+
+    if (!response.ok) {
+      throw new Error(`HTTP ${response.status}`)
+    }
+
+    const html = await response.text()
+    return this.parseHtml(url, html)
+  }
+
+  /**
+   * Fetch via CORS proxy
+   */
+  private async fetchViaProxy(url: string): Promise<LinkPreview> {
+    const proxyUrl = `${this.proxyUrl}${encodeURIComponent(url)}`
+
+    const response = await fetch(proxyUrl, {
+      method: 'GET',
+      headers: {
+        'Accept': 'text/html'
+      }
+    })
+
+    if (!response.ok) {
+      throw new Error(`Proxy HTTP ${response.status}`)
+    }
+
+    const html = await response.text()
+    return this.parseHtml(url, html)
+  }
+
+  /**
+   * Try oEmbed for supported providers
+   */
+  private async fetchOembed(url: string): Promise<LinkPreview> {
+    // oEmbed providers and their endpoints
+    const providers = [
+      {
+        pattern: /youtube\.com\/watch|youtu\.be/,
+        endpoint: 'https://www.youtube.com/oembed'
+      },
+      {
+        pattern: /twitter\.com|x\.com/,
+        endpoint: 'https://publish.twitter.com/oembed'
+      },
+      {
+        pattern: /vimeo\.com/,
+        endpoint: 'https://vimeo.com/api/oembed.json'
+      }
+    ]
+
+    const provider = providers.find(p => p.pattern.test(url))
+    if (!provider) {
+      throw new Error('No oEmbed provider for URL')
+    }
+
+    const oembedUrl = `${provider.endpoint}?url=${encodeURIComponent(url)}&format=json`
+    const response = await fetch(oembedUrl)
+
+    if (!response.ok) {
+      throw new Error(`oEmbed HTTP ${response.status}`)
+    }
+
+    const data = await response.json()
+
+    return {
+      url,
+      domain: extractDomain(url),
+      title: data.title,
+      description: data.description || data.author_name,
+      image: data.thumbnail_url,
+      siteName: data.provider_name,
+      type: data.type,
+      videoUrl: data.html?.includes('iframe') ? url : undefined
+    }
+  }
+
+  // ============================================================================
+  // HTML Parsing
+  // ============================================================================
+
+  /**
+   * Parse HTML to extract Open Graph and meta tags
+   */
+  private parseHtml(url: string, html: string): LinkPreview {
+    const preview: LinkPreview = {
+      url,
+      domain: extractDomain(url)
+    }
+
+    // Create a DOM parser
+    const parser = new DOMParser()
+    const doc = parser.parseFromString(html, 'text/html')
+
+    // Extract Open Graph tags
+    const ogTags = this.extractOgTags(doc)
+
+    // Extract Twitter Card tags (fallback)
+    const twitterTags = this.extractTwitterTags(doc)
+
+    // Extract standard meta tags (fallback)
+    const metaTags = this.extractMetaTags(doc)
+
+    // Merge with priority: OG > Twitter > Meta > Title
+    preview.title = ogTags.title || twitterTags.title || metaTags.title || this.extractTitle(doc)
+    preview.description = ogTags.description || twitterTags.description || metaTags.description
+    preview.image = ogTags.image || twitterTags.image
+    preview.siteName = ogTags.siteName || twitterTags.site
+    preview.type = ogTags.type
+    preview.videoUrl = ogTags.video
+    preview.favicon = this.extractFavicon(doc, url)
+
+    return preview
+  }
+
+  /**
+   * Extract Open Graph tags
+   */
+  private extractOgTags(doc: Document): Record<string, string | undefined> {
+    const tags: Record<string, string | undefined> = {}
+
+    const ogMetas = doc.querySelectorAll('meta[property^="og:"]')
+    ogMetas.forEach(meta => {
+      const property = meta.getAttribute('property')?.replace('og:', '')
+      const content = meta.getAttribute('content')
+      if (property && content) {
+        switch (property) {
+          case 'title':
+            tags.title = content
+            break
+          case 'description':
+            tags.description = content
+            break
+          case 'image':
+            tags.image = content
+            break
+          case 'site_name':
+            tags.siteName = content
+            break
+          case 'type':
+            tags.type = content
+            break
+          case 'video':
+          case 'video:url':
+            tags.video = content
+            break
+        }
+      }
+    })
+
+    return tags
+  }
+
+  /**
+   * Extract Twitter Card tags
+   */
+  private extractTwitterTags(doc: Document): Record<string, string | undefined> {
+    const tags: Record<string, string | undefined> = {}
+
+    const twitterMetas = doc.querySelectorAll('meta[name^="twitter:"]')
+    twitterMetas.forEach(meta => {
+      const name = meta.getAttribute('name')?.replace('twitter:', '')
+      const content = meta.getAttribute('content')
+      if (name && content) {
+        switch (name) {
+          case 'title':
+            tags.title = content
+            break
+          case 'description':
+            tags.description = content
+            break
+          case 'image':
+          case 'image:src':
+            tags.image = content
+            break
+          case 'site':
+            tags.site = content
+            break
+        }
+      }
+    })
+
+    return tags
+  }
+
+  /**
+   * Extract standard meta tags
+   */
+  private extractMetaTags(doc: Document): Record<string, string | undefined> {
+    const tags: Record<string, string | undefined> = {}
+
+    // Description
+    const descMeta = doc.querySelector('meta[name="description"]')
+    if (descMeta) {
+      tags.description = descMeta.getAttribute('content') || undefined
+    }
+
+    // Title from meta
+    const titleMeta = doc.querySelector('meta[name="title"]')
+    if (titleMeta) {
+      tags.title = titleMeta.getAttribute('content') || undefined
+    }
+
+    return tags
+  }
+
+  /**
+   * Extract page title
+   */
+  private extractTitle(doc: Document): string | undefined {
+    return doc.querySelector('title')?.textContent || undefined
+  }
+
+  /**
+   * Extract favicon URL
+   */
+  private extractFavicon(doc: Document, pageUrl: string): string | undefined {
+    // Try various link rel types
+    const selectors = [
+      'link[rel="icon"]',
+      'link[rel="shortcut icon"]',
+      'link[rel="apple-touch-icon"]'
+    ]
+
+    for (const selector of selectors) {
+      const link = doc.querySelector(selector)
+      const href = link?.getAttribute('href')
+      if (href) {
+        return this.resolveUrl(href, pageUrl)
+      }
+    }
+
+    // Default favicon location
+    return this.resolveUrl('/favicon.ico', pageUrl)
+  }
+
+  // ============================================================================
+  // Utilities
+  // ============================================================================
+
+  /**
+   * Normalize URL
+   */
+  private normalizeUrl(url: string): string {
+    let normalized = url.trim()
+
+    // Add protocol if missing
+    if (!normalized.startsWith('http://') && !normalized.startsWith('https://')) {
+      normalized = 'https://' + normalized
+    }
+
+    return normalized
+  }
+
+  /**
+   * Resolve relative URL to absolute
+   */
+  private resolveUrl(href: string, base: string): string {
+    try {
+      return new URL(href, base).toString()
+    } catch {
+      return href
+    }
+  }
+
+  /**
+   * Wait for an in-flight preview request
+   */
+  private async waitForPreview(url: string): Promise<LinkPreview> {
+    // Poll until loading is done
+    while (this._loading.get(url)) {
+      await new Promise(resolve => setTimeout(resolve, 100))
+    }
+
+    // Return cached result or error
+    const cached = this.getCachedPreview(url)
+    if (cached) return cached
+
+    return {
+      url,
+      domain: extractDomain(url)
+    }
+  }
+
+  /**
+   * Clean expired cache entries
+   */
+  private cleanCache(): void {
+    const now = Date.now()
+
+    for (const [url, entry] of this.cache) {
+      if (now - entry.timestamp > this.CACHE_TTL) {
+        this.cache.delete(url)
+      }
+    }
+  }
+
+  // ============================================================================
+  // Validation
+  // ============================================================================
+
+  /**
+   * Check if URL is valid
+   */
+  isValidUrl(url: string): boolean {
+    try {
+      const parsed = new URL(this.normalizeUrl(url))
+      return parsed.protocol === 'http:' || parsed.protocol === 'https:'
+    } catch {
+      return false
+    }
+  }
+
+  /**
+   * Check if URL is likely to be media
+   */
+  isMediaUrl(url: string): boolean {
+    const mediaExtensions = [
+      '.jpg', '.jpeg', '.png', '.gif', '.webp', '.svg',
+      '.mp4', '.webm', '.mov', '.avi',
+      '.mp3', '.wav', '.ogg', '.flac'
+    ]
+
+    const lowerUrl = url.toLowerCase()
+    return mediaExtensions.some(ext => lowerUrl.includes(ext))
+  }
+
+  /**
+   * Guess media type from URL
+   */
+  guessMediaType(url: string): 'image' | 'video' | 'audio' | 'other' {
+    const lowerUrl = url.toLowerCase()
+
+    if (/\.(jpg|jpeg|png|gif|webp|svg)/.test(lowerUrl)) return 'image'
+    if (/\.(mp4|webm|mov|avi)/.test(lowerUrl)) return 'video'
+    if (/\.(mp3|wav|ogg|flac)/.test(lowerUrl)) return 'audio'
+
+    return 'other'
+  }
+}

src/modules/nostr-feed/services/SubmissionService.ts

@@ -0,0 +1,957 @@
+/**
+ * SubmissionService
+ *
+ * Handles Reddit-style submissions (link, media, self posts) using NIP-72 and NIP-22.
+ * Submissions are kind 1111 events scoped to a community with structured metadata.
+ */
+
+import { ref, reactive, computed } from 'vue'
+import { BaseService } from '@/core/base/BaseService'
+import { injectService, SERVICE_TOKENS } from '@/core/di-container'
+import { eventBus } from '@/core/event-bus'
+import { finalizeEvent, type EventTemplate } from 'nostr-tools'
+import type { Event as NostrEvent, Filter } from 'nostr-tools'
+
+import {
+  SUBMISSION_KINDS,
+  type Submission,
+  type LinkSubmission,
+  type MediaSubmission,
+  type SelfSubmission,
+  type SubmissionType,
+  type SubmissionWithMeta,
+  type SubmissionVotes,
+  type SubmissionRanking,
+  type SubmissionForm,
+  type LinkSubmissionForm,
+  type MediaSubmissionForm,
+  type SelfSubmissionForm,
+  type SubmissionFeedConfig,
+  type SubmissionComment,
+  type LinkPreview,
+  type MediaAttachment,
+  type CommunityRef,
+  parseCommunityRef,
+  formatCommunityRef,
+  extractDomain,
+  parseImetaTag,
+  buildImetaTag,
+  calculateHotRank,
+  calculateControversyRank
+} from '../types/submission'
+
+// ============================================================================
+// Service Definition
+// ============================================================================
+
+export class SubmissionService extends BaseService {
+  protected readonly metadata = {
+    name: 'SubmissionService',
+    version: '1.0.0',
+    dependencies: ['RelayHub', 'AuthService']
+  }
+
+  // Injected services
+  protected relayHub: any = null
+  protected authService: any = null
+  protected visibilityService: any = null
+  protected reactionService: any = null
+  protected linkPreviewService: any = null
+
+  // State
+  private _submissions = reactive(new Map<string, SubmissionWithMeta>())
+  private _comments = reactive(new Map<string, SubmissionComment[]>())
+  private _isLoading = ref(false)
+  private _error = ref<string | null>(null)
+
+  // Deduplication
+  private seenEventIds = new Set<string>()
+
+  // Subscription management
+  private currentSubscription: string | null = null
+  private currentUnsubscribe: (() => void) | null = null
+
+  // Public reactive state
+  public readonly submissions = computed(() => Array.from(this._submissions.values()))
+  public readonly isLoading = computed(() => this._isLoading.value)
+  public readonly error = computed(() => this._error.value)
+
+  // ============================================================================
+  // Lifecycle
+  // ============================================================================
+
+  protected async onInitialize(): Promise<void> {
+    console.log('SubmissionService: Starting initialization...')
+
+    this.relayHub = injectService(SERVICE_TOKENS.RELAY_HUB)
+    this.authService = injectService(SERVICE_TOKENS.AUTH_SERVICE)
+    this.visibilityService = injectService(SERVICE_TOKENS.VISIBILITY_SERVICE)
+    this.reactionService = injectService(SERVICE_TOKENS.REACTION_SERVICE)
+
+    if (!this.relayHub) {
+      throw new Error('RelayHub service not available')
+    }
+
+    // Register with visibility service
+    if (this.visibilityService) {
+      this.visibilityService.registerService(
+        'SubmissionService',
+        this.onResume.bind(this),
+        this.onPause.bind(this)
+      )
+    }
+
+    console.log('SubmissionService: Initialization complete')
+  }
+
+  private async onResume(): Promise<void> {
+    this.debug('App resumed')
+  }
+
+  private onPause(): void {
+    this.debug('App paused')
+  }
+
+  protected async onDispose(): Promise<void> {
+    await this.unsubscribe()
+    this._submissions.clear()
+    this._comments.clear()
+    this.seenEventIds.clear()
+  }
+
+  // ============================================================================
+  // Subscription Management
+  // ============================================================================
+
+  /**
+   * Subscribe to submissions based on feed configuration
+   */
+  async subscribe(config: SubmissionFeedConfig): Promise<void> {
+    await this.unsubscribe()
+
+    this._isLoading.value = true
+    this._error.value = null
+
+    try {
+      if (!this.relayHub?.isConnected) {
+        await this.relayHub?.connect()
+      }
+
+      const subscriptionId = `submissions-${Date.now()}`
+      const filters = this.buildFilters(config)
+
+      this.debug('Subscribing with filters:', filters)
+
+      const unsubscribe = this.relayHub.subscribe({
+        id: subscriptionId,
+        filters,
+        onEvent: (event: NostrEvent) => this.handleEvent(event),
+        onEose: () => {
+          this.debug('End of stored events')
+          this._isLoading.value = false
+        },
+        onClose: () => {
+          this.debug('Subscription closed')
+        }
+      })
+
+      this.currentSubscription = subscriptionId
+      this.currentUnsubscribe = unsubscribe
+
+      // Timeout fallback
+      setTimeout(() => {
+        if (this._isLoading.value && this.currentSubscription === subscriptionId) {
+          this._isLoading.value = false
+        }
+      }, 10000)
+
+    } catch (err) {
+      this._error.value = err instanceof Error ? err.message : 'Failed to subscribe'
+      this._isLoading.value = false
+      throw err
+    }
+  }
+
+  /**
+   * Unsubscribe from current feed
+   */
+  async unsubscribe(): Promise<void> {
+    if (this.currentUnsubscribe) {
+      this.currentUnsubscribe()
+      this.currentSubscription = null
+      this.currentUnsubscribe = null
+    }
+  }
+
+  /**
+   * Build Nostr filters from feed configuration
+   */
+  private buildFilters(config: SubmissionFeedConfig): Filter[] {
+    const filters: Filter[] = []
+
+    // Main submissions filter
+    const submissionFilter: Filter = {
+      kinds: [SUBMISSION_KINDS.SUBMISSION],
+      limit: config.limit
+    }
+
+    // Community filter
+    if (config.community) {
+      submissionFilter['#a'] = [formatCommunityRef(config.community)]
+    }
+
+    // Author filter
+    if (config.authors?.length) {
+      submissionFilter.authors = config.authors
+    }
+
+    // Hashtag filter
+    if (config.hashtags?.length) {
+      submissionFilter['#t'] = config.hashtags
+    }
+
+    // Time range for "top" sort
+    if (config.sort === 'top' && config.timeRange) {
+      const now = Math.floor(Date.now() / 1000)
+      const ranges: Record<string, number> = {
+        hour: 3600,
+        day: 86400,
+        week: 604800,
+        month: 2592000,
+        year: 31536000,
+        all: 0
+      }
+      if (ranges[config.timeRange] > 0) {
+        submissionFilter.since = now - ranges[config.timeRange]
+      }
+    }
+
+    filters.push(submissionFilter)
+
+    // Also subscribe to reactions for these submissions
+    filters.push({
+      kinds: [SUBMISSION_KINDS.REACTION],
+      limit: 1000
+    })
+
+    // And deletions
+    filters.push({
+      kinds: [SUBMISSION_KINDS.DELETION]
+    })
+
+    return filters
+  }
+
+  // ============================================================================
+  // Event Handling
+  // ============================================================================
+
+  /**
+   * Handle incoming Nostr event
+   */
+  private handleEvent(event: NostrEvent): void {
+    switch (event.kind) {
+      case SUBMISSION_KINDS.SUBMISSION:
+        this.handleSubmissionEvent(event)
+        break
+      case SUBMISSION_KINDS.REACTION:
+        // Route to reaction service
+        this.reactionService?.handleReactionEvent(event)
+        break
+      case SUBMISSION_KINDS.DELETION:
+        this.handleDeletionEvent(event)
+        break
+    }
+  }
+
+  /**
+   * Handle kind 1111 submission event
+   */
+  private handleSubmissionEvent(event: NostrEvent): void {
+    // Deduplication
+    if (this.seenEventIds.has(event.id)) {
+      return
+    }
+    this.seenEventIds.add(event.id)
+
+    // Parse the submission
+    const submission = this.parseSubmission(event)
+    if (!submission) {
+      this.debug('Failed to parse submission:', event.id)
+      return
+    }
+
+    // Check if this is a top-level submission or a comment
+    if (this.isComment(event)) {
+      this.handleCommentEvent(event)
+      return
+    }
+
+    // Create full submission with metadata
+    const submissionWithMeta = this.enrichSubmission(submission)
+    this._submissions.set(submission.id, submissionWithMeta)
+
+    // Emit event
+    eventBus.emit('submission:new', { submission: submissionWithMeta }, 'nostr-feed')
+  }
+
+  /**
+   * Check if event is a comment (has parent that's not the community)
+   */
+  private isComment(event: NostrEvent): boolean {
+    const tags = event.tags || []
+
+    // Get root scope (A tag) and parent (a/e tag)
+    const rootTag = tags.find(t => t[0] === 'A')
+    const parentETag = tags.find(t => t[0] === 'e')
+    const parentATag = tags.find(t => t[0] === 'a' && t[1] !== rootTag?.[1])
+
+    // If parent e-tag exists and points to a different event, it's a comment
+    if (parentETag) {
+      return true
+    }
+
+    // If parent a-tag differs from root A-tag, it's a comment
+    if (parentATag && rootTag && parentATag[1] !== rootTag[1]) {
+      return true
+    }
+
+    return false
+  }
+
+  /**
+   * Handle comment on a submission
+   */
+  private handleCommentEvent(event: NostrEvent): void {
+    // Find the root submission ID
+    const rootTag = event.tags.find(t => t[0] === 'E') || event.tags.find(t => t[0] === 'e')
+    if (!rootTag) return
+
+    const rootId = rootTag[1]
+
+    // Parse as comment
+    const comment: SubmissionComment = {
+      id: event.id,
+      pubkey: event.pubkey,
+      created_at: event.created_at,
+      content: event.content,
+      rootId,
+      parentId: this.getParentId(event) || rootId,
+      depth: 0,
+      replies: [],
+      votes: this.getDefaultVotes()
+    }
+
+    // Add to comments map
+    if (!this._comments.has(rootId)) {
+      this._comments.set(rootId, [])
+    }
+    this._comments.get(rootId)!.push(comment)
+  }
+
+  /**
+   * Get parent event ID from tags
+   */
+  private getParentId(event: NostrEvent): string | null {
+    const eTag = event.tags.find(t => t[0] === 'e')
+    return eTag ? eTag[1] : null
+  }
+
+  /**
+   * Handle deletion event
+   */
+  private handleDeletionEvent(event: NostrEvent): void {
+    const kTag = event.tags.find(t => t[0] === 'k')
+    const deletedKind = kTag?.[1]
+
+    // Route reaction deletions to reaction service
+    if (deletedKind === '7') {
+      this.reactionService?.handleDeletionEvent(event)
+      return
+    }
+
+    // Handle submission/comment deletions
+    if (deletedKind === '1111') {
+      const eTags = event.tags.filter(t => t[0] === 'e')
+      for (const eTag of eTags) {
+        const eventId = eTag[1]
+        const submission = this._submissions.get(eventId)
+
+        // Only delete if from the same author
+        if (submission && submission.pubkey === event.pubkey) {
+          this._submissions.delete(eventId)
+          this.seenEventIds.delete(eventId)
+        }
+      }
+    }
+  }
+
+  // ============================================================================
+  // Parsing
+  // ============================================================================
+
+  /**
+   * Parse a Nostr event into a Submission
+   */
+  private parseSubmission(event: NostrEvent): Submission | null {
+    const tags = event.tags || []
+
+    // Extract required fields
+    const titleTag = tags.find(t => t[0] === 'title')
+    const postTypeTag = tags.find(t => t[0] === 'post-type')
+
+    // Title is required
+    const title = titleTag?.[1]
+    if (!title) {
+      this.debug('Submission missing title:', event.id)
+      return null
+    }
+
+    // Determine post type
+    const postType = (postTypeTag?.[1] as SubmissionType) || this.inferPostType(event)
+
+    // Extract common fields
+    const base = {
+      id: event.id,
+      pubkey: event.pubkey,
+      created_at: event.created_at,
+      kind: SUBMISSION_KINDS.SUBMISSION as const,
+      tags,
+      title,
+      communityRef: this.extractCommunityRef(tags),
+      hashtags: this.extractHashtags(tags),
+      nsfw: tags.some(t => t[0] === 'nsfw' || (t[0] === 'content-warning')),
+      flair: tags.find(t => t[0] === 'flair')?.[1]
+    }
+
+    // Build type-specific submission
+    switch (postType) {
+      case 'link':
+        return this.parseLinkSubmission(event, base)
+      case 'media':
+        return this.parseMediaSubmission(event, base)
+      case 'self':
+      default:
+        return this.parseSelfSubmission(event, base)
+    }
+  }
+
+  /**
+   * Infer post type from event content/tags
+   */
+  private inferPostType(event: NostrEvent): SubmissionType {
+    const tags = event.tags || []
+
+    // Check for URL tag
+    const urlTag = tags.find(t => t[0] === 'r')
+    if (urlTag) return 'link'
+
+    // Check for media (imeta tag)
+    const imetaTag = tags.find(t => t[0] === 'imeta')
+    if (imetaTag) return 'media'
+
+    // Check for URL in content
+    const urlRegex = /https?:\/\/[^\s]+/
+    if (urlRegex.test(event.content)) {
+      // Check if it's a media URL
+      const mediaExtensions = ['.jpg', '.jpeg', '.png', '.gif', '.webp', '.mp4', '.webm', '.mov']
+      const match = event.content.match(urlRegex)
+      if (match && mediaExtensions.some(ext => match[0].toLowerCase().includes(ext))) {
+        return 'media'
+      }
+      return 'link'
+    }
+
+    return 'self'
+  }
+
+  /**
+   * Parse link submission
+   */
+  private parseLinkSubmission(
+    event: NostrEvent,
+    base: Omit<Submission, 'postType' | 'url' | 'preview' | 'body'>
+  ): LinkSubmission {
+    const tags = event.tags || []
+
+    // Get URL from 'r' tag or content
+    const urlTag = tags.find(t => t[0] === 'r')
+    let url = urlTag?.[1] || ''
+
+    if (!url) {
+      const urlMatch = event.content.match(/https?:\/\/[^\s]+/)
+      url = urlMatch?.[0] || ''
+    }
+
+    // Build preview from tags
+    const preview: LinkPreview = {
+      url,
+      domain: extractDomain(url),
+      title: tags.find(t => t[0] === 'preview-title')?.[1],
+      description: tags.find(t => t[0] === 'preview-description')?.[1],
+      image: tags.find(t => t[0] === 'preview-image')?.[1],
+      siteName: tags.find(t => t[0] === 'preview-site-name')?.[1]
+    }
+
+    return {
+      ...base,
+      postType: 'link',
+      url,
+      preview,
+      body: event.content
+    }
+  }
+
+  /**
+   * Parse media submission
+   */
+  private parseMediaSubmission(
+    event: NostrEvent,
+    base: Omit<Submission, 'postType' | 'media' | 'gallery' | 'body'>
+  ): MediaSubmission {
+    const tags = event.tags || []
+
+    // Parse imeta tags
+    const imetaTags = tags.filter(t => t[0] === 'imeta')
+    const mediaAttachments = imetaTags
+      .map(t => parseImetaTag(t))
+      .filter((m): m is MediaAttachment => m !== null)
+
+    // If no imeta, try to extract from content
+    if (mediaAttachments.length === 0) {
+      const urlMatch = event.content.match(/https?:\/\/[^\s]+/)
+      if (urlMatch) {
+        mediaAttachments.push({ url: urlMatch[0] })
+      }
+    }
+
+    const [primary, ...gallery] = mediaAttachments
+
+    return {
+      ...base,
+      postType: 'media',
+      media: primary || { url: '' },
+      gallery: gallery.length > 0 ? gallery : undefined,
+      body: event.content
+    }
+  }
+
+  /**
+   * Parse self/text submission
+   */
+  private parseSelfSubmission(
+    event: NostrEvent,
+    base: Omit<Submission, 'postType' | 'body'>
+  ): SelfSubmission {
+    return {
+      ...base,
+      postType: 'self',
+      body: event.content
+    }
+  }
+
+  /**
+   * Extract community reference from tags
+   */
+  private extractCommunityRef(tags: string[][]): string | undefined {
+    const aTag = tags.find(t => t[0] === 'A' || t[0] === 'a')
+    return aTag?.[1]
+  }
+
+  /**
+   * Extract hashtags from tags
+   */
+  private extractHashtags(tags: string[][]): string[] {
+    return tags.filter(t => t[0] === 't').map(t => t[1])
+  }
+
+  // ============================================================================
+  // Enrichment
+  // ============================================================================
+
+  /**
+   * Enrich submission with votes, ranking, etc.
+   */
+  private enrichSubmission(submission: Submission): SubmissionWithMeta {
+    const votes = this.getSubmissionVotes(submission.id)
+    const ranking = this.calculateRanking(submission, votes)
+
+    return {
+      ...submission,
+      votes,
+      ranking,
+      commentCount: this.getCommentCount(submission.id),
+      isSaved: false, // TODO: implement saved posts
+      isHidden: false,
+      approvalStatus: null
+    }
+  }
+
+  /**
+   * Get votes for a submission
+   */
+  private getSubmissionVotes(submissionId: string): SubmissionVotes {
+    // Get from reaction service if available
+    if (this.reactionService) {
+      const reactions = this.reactionService.getEventReactions(submissionId)
+      return {
+        upvotes: reactions.likes || 0,
+        downvotes: reactions.dislikes || 0,
+        score: (reactions.likes || 0) - (reactions.dislikes || 0),
+        userVote: reactions.userHasLiked ? 'upvote' : reactions.userHasDisliked ? 'downvote' : null,
+        userVoteId: reactions.userReactionId
+      }
+    }
+    return this.getDefaultVotes()
+  }
+
+  /**
+   * Get default votes object
+   */
+  private getDefaultVotes(): SubmissionVotes {
+    return {
+      upvotes: 0,
+      downvotes: 0,
+      score: 0,
+      userVote: null
+    }
+  }
+
+  /**
+   * Calculate ranking scores
+   */
+  private calculateRanking(submission: Submission, votes: SubmissionVotes): SubmissionRanking {
+    return {
+      hotRank: calculateHotRank(votes.score, submission.created_at),
+      controversyRank: calculateControversyRank(votes.upvotes, votes.downvotes),
+      scaledRank: 0 // TODO: implement community scaling
+    }
+  }
+
+  /**
+   * Get comment count for a submission
+   */
+  private getCommentCount(submissionId: string): number {
+    return this._comments.get(submissionId)?.length || 0
+  }
+
+  // ============================================================================
+  // Submission Creation
+  // ============================================================================
+
+  /**
+   * Create a new submission
+   */
+  async createSubmission(form: SubmissionForm): Promise<string> {
+    this.requireAuth()
+
+    const userPubkey = this.authService.user.value?.pubkey
+    const userPrivkey = this.authService.user.value?.prvkey
+
+    if (!userPubkey || !userPrivkey) {
+      throw new Error('User keys not available')
+    }
+
+    try {
+      this._isLoading.value = true
+
+      // Build event
+      const eventTemplate = await this.buildSubmissionEvent(form)
+
+      // Sign
+      const privkeyBytes = this.hexToUint8Array(userPrivkey)
+      const signedEvent = finalizeEvent(eventTemplate, privkeyBytes)
+
+      // Publish
+      await this.relayHub.publishEvent(signedEvent)
+
+      // Handle locally
+      this.handleSubmissionEvent(signedEvent)
+
+      return signedEvent.id
+
+    } finally {
+      this._isLoading.value = false
+    }
+  }
+
+  /**
+   * Build event template from submission form
+   */
+  private async buildSubmissionEvent(form: SubmissionForm): Promise<EventTemplate> {
+    const tags: string[][] = []
+
+    // Title (required)
+    tags.push(['title', form.title])
+
+    // Post type
+    tags.push(['post-type', form.postType])
+
+    // Community scope (if provided)
+    if (form.communityRef) {
+      const ref = parseCommunityRef(form.communityRef)
+      if (ref) {
+        tags.push(['A', form.communityRef])
+        tags.push(['a', form.communityRef])
+        tags.push(['K', '34550'])
+        tags.push(['k', '34550'])
+        tags.push(['P', ref.pubkey])
+        tags.push(['p', ref.pubkey])
+      }
+    }
+
+    // NSFW
+    if (form.nsfw) {
+      tags.push(['nsfw', 'true'])
+    }
+
+    // Flair
+    if (form.flair) {
+      tags.push(['flair', form.flair])
+    }
+
+    let content = ''
+
+    // Type-specific fields
+    switch (form.postType) {
+      case 'link': {
+        const linkForm = form as LinkSubmissionForm
+        tags.push(['r', linkForm.url])
+
+        // Fetch and add preview if available
+        if (this.linkPreviewService) {
+          try {
+            const preview = await this.linkPreviewService.fetchPreview(linkForm.url)
+            if (preview.title) tags.push(['preview-title', preview.title])
+            if (preview.description) tags.push(['preview-description', preview.description])
+            if (preview.image) tags.push(['preview-image', preview.image])
+            if (preview.siteName) tags.push(['preview-site-name', preview.siteName])
+          } catch (err) {
+            this.debug('Failed to fetch link preview:', err)
+          }
+        }
+
+        content = linkForm.body || ''
+        break
+      }
+
+      case 'media': {
+        const mediaForm = form as MediaSubmissionForm
+
+        // Handle file upload or URL
+        let mediaUrl: string
+        if (typeof mediaForm.media === 'string') {
+          mediaUrl = mediaForm.media
+        } else {
+          // TODO: Upload file and get URL
+          throw new Error('File upload not yet implemented')
+        }
+
+        // Add imeta tag
+        const imetaTag = buildImetaTag({
+          url: mediaUrl,
+          alt: mediaForm.alt
+        })
+        tags.push(imetaTag)
+
+        content = mediaForm.body || ''
+        break
+      }
+
+      case 'self': {
+        const selfForm = form as SelfSubmissionForm
+        content = selfForm.body
+        break
+      }
+    }
+
+    return {
+      kind: SUBMISSION_KINDS.SUBMISSION,
+      content,
+      tags,
+      created_at: Math.floor(Date.now() / 1000)
+    }
+  }
+
+  // ============================================================================
+  // Voting
+  // ============================================================================
+
+  /**
+   * Upvote a submission
+   */
+  async upvote(submissionId: string): Promise<void> {
+    const submission = this._submissions.get(submissionId)
+    if (!submission) throw new Error('Submission not found')
+
+    if (submission.votes.userVote === 'upvote') {
+      // Remove upvote
+      await this.reactionService?.unlikeEvent(submissionId)
+    } else {
+      // Add upvote (reaction service handles removing existing downvote)
+      await this.reactionService?.likeEvent(
+        submissionId,
+        submission.pubkey,
+        SUBMISSION_KINDS.SUBMISSION
+      )
+    }
+
+    // Refresh votes
+    this.refreshSubmissionVotes(submissionId)
+  }
+
+  /**
+   * Downvote a submission
+   */
+  async downvote(submissionId: string): Promise<void> {
+    // TODO: Implement downvote using '-' reaction content
+    // For now, this is a placeholder that mirrors the upvote logic
+    const submission = this._submissions.get(submissionId)
+    if (!submission) throw new Error('Submission not found')
+
+    this.debug('Downvote not yet implemented')
+  }
+
+  /**
+   * Refresh votes for a submission
+   */
+  private refreshSubmissionVotes(submissionId: string): void {
+    const submission = this._submissions.get(submissionId)
+    if (!submission) return
+
+    submission.votes = this.getSubmissionVotes(submissionId)
+    submission.ranking = this.calculateRanking(submission, submission.votes)
+  }
+
+  // ============================================================================
+  // Sorting
+  // ============================================================================
+
+  /**
+   * Get sorted submissions
+   */
+  getSortedSubmissions(
+    sort: 'hot' | 'new' | 'top' | 'controversial' = 'hot'
+  ): SubmissionWithMeta[] {
+    const submissions = Array.from(this._submissions.values())
+
+    switch (sort) {
+      case 'hot':
+        return submissions.sort((a, b) => b.ranking.hotRank - a.ranking.hotRank)
+      case 'new':
+        return submissions.sort((a, b) => b.created_at - a.created_at)
+      case 'top':
+        return submissions.sort((a, b) => b.votes.score - a.votes.score)
+      case 'controversial':
+        return submissions.sort((a, b) => b.ranking.controversyRank - a.ranking.controversyRank)
+      default:
+        return submissions
+    }
+  }
+
+  // ============================================================================
+  // Comments
+  // ============================================================================
+
+  /**
+   * Get comments for a submission
+   */
+  getComments(submissionId: string): SubmissionComment[] {
+    return this._comments.get(submissionId) || []
+  }
+
+  /**
+   * Get threaded comments
+   */
+  getThreadedComments(submissionId: string): SubmissionComment[] {
+    const comments = this.getComments(submissionId)
+    return this.buildCommentTree(comments)
+  }
+
+  /**
+   * Build comment tree from flat list
+   */
+  private buildCommentTree(comments: SubmissionComment[]): SubmissionComment[] {
+    const commentMap = new Map<string, SubmissionComment>()
+    const rootComments: SubmissionComment[] = []
+
+    // Create map
+    comments.forEach(comment => {
+      commentMap.set(comment.id, { ...comment, replies: [], depth: 0 })
+    })
+
+    // Build tree
+    comments.forEach(comment => {
+      const current = commentMap.get(comment.id)!
+
+      if (comment.parentId === comment.rootId) {
+        // Top-level comment
+        rootComments.push(current)
+      } else {
+        // Nested reply
+        const parent = commentMap.get(comment.parentId)
+        if (parent) {
+          current.depth = parent.depth + 1
+          parent.replies.push(current)
+        } else {
+          // Parent not found, treat as root
+          rootComments.push(current)
+        }
+      }
+    })
+
+    // Sort by score
+    const sortByScore = (a: SubmissionComment, b: SubmissionComment) =>
+      b.votes.score - a.votes.score
+
+    rootComments.sort(sortByScore)
+    rootComments.forEach(comment => this.sortReplies(comment, sortByScore))
+
+    return rootComments
+  }
+
+  /**
+   * Recursively sort replies
+   */
+  private sortReplies(
+    comment: SubmissionComment,
+    compareFn: (a: SubmissionComment, b: SubmissionComment) => number
+  ): void {
+    if (comment.replies.length > 0) {
+      comment.replies.sort(compareFn)
+      comment.replies.forEach(reply => this.sortReplies(reply, compareFn))
+    }
+  }
+
+  // ============================================================================
+  // Utilities
+  // ============================================================================
+
+  /**
+   * Convert hex string to Uint8Array
+   */
+  private hexToUint8Array(hex: string): Uint8Array {
+    const bytes = new Uint8Array(hex.length / 2)
+    for (let i = 0; i < hex.length; i += 2) {
+      bytes[i / 2] = parseInt(hex.substr(i, 2), 16)
+    }
+    return bytes
+  }
+
+  /**
+   * Get a single submission by ID
+   */
+  getSubmission(id: string): SubmissionWithMeta | undefined {
+    return this._submissions.get(id)
+  }
+
+  /**
+   * Clear all data
+   */
+  clear(): void {
+    this._submissions.clear()
+    this._comments.clear()
+    this.seenEventIds.clear()
+    this._error.value = null
+  }
+}

src/modules/nostr-feed/types/index.ts

@@ -0,0 +1,5 @@
+/**
+ * Types index - re-export all types from the module
+ */
+
+export * from './submission'

src/modules/nostr-feed/types/submission.ts

@@ -0,0 +1,529 @@
+/**
+ * Link Aggregator Types
+ *
+ * Implements Reddit-style submissions using NIP-72 (Communities) and NIP-22 (Comments).
+ * Submissions are kind 1111 events scoped to a community with structured metadata.
+ */
+
+import type { Event as NostrEvent } from 'nostr-tools'
+
+// ============================================================================
+// Constants
+// ============================================================================
+
+/** Nostr event kinds used by the link aggregator */
+export const SUBMISSION_KINDS = {
+  /** Community definition (NIP-72) */
+  COMMUNITY: 34550,
+  /** Submission/comment (NIP-22) */
+  SUBMISSION: 1111,
+  /** Moderator approval (NIP-72) */
+  APPROVAL: 4550,
+  /** Reaction/vote (NIP-25) */
+  REACTION: 7,
+  /** Deletion (NIP-09) */
+  DELETION: 5,
+  /** File metadata (NIP-94) - for media references */
+  FILE_METADATA: 1063
+} as const
+
+/** Submission post types */
+export type SubmissionType = 'link' | 'media' | 'self'
+
+/** Vote types for reactions */
+export type VoteType = 'upvote' | 'downvote' | null
+
+/** Feed sort options */
+export type SortType = 'hot' | 'new' | 'top' | 'controversial'
+
+/** Time range for "top" sorting */
+export type TimeRange = 'hour' | 'day' | 'week' | 'month' | 'year' | 'all'
+
+// ============================================================================
+// Link Preview Types
+// ============================================================================
+
+/** Open Graph metadata extracted from a URL */
+export interface LinkPreview {
+  /** The original URL */
+  url: string
+  /** og:title or page title */
+  title?: string
+  /** og:description or meta description */
+  description?: string
+  /** og:image URL */
+  image?: string
+  /** og:site_name */
+  siteName?: string
+  /** og:type (article, video, etc.) */
+  type?: string
+  /** og:video for video embeds */
+  videoUrl?: string
+  /** Favicon URL */
+  favicon?: string
+  /** Domain extracted from URL */
+  domain: string
+}
+
+// ============================================================================
+// Media Types (NIP-92 / NIP-94)
+// ============================================================================
+
+/** Media attachment metadata from imeta tag */
+export interface MediaAttachment {
+  /** Media URL */
+  url: string
+  /** MIME type (e.g., "image/jpeg", "video/mp4") */
+  mimeType?: string
+  /** Dimensions in "WxH" format */
+  dimensions?: string
+  /** Width in pixels */
+  width?: number
+  /** Height in pixels */
+  height?: number
+  /** Blurhash for placeholder */
+  blurhash?: string
+  /** Alt text for accessibility */
+  alt?: string
+  /** SHA-256 hash of the file */
+  hash?: string
+  /** File size in bytes */
+  size?: number
+  /** Thumbnail URL */
+  thumbnail?: string
+  /** Fallback URLs */
+  fallbacks?: string[]
+}
+
+/** Media type classification */
+export type MediaType = 'image' | 'video' | 'audio' | 'other'
+
+// ============================================================================
+// Submission Types
+// ============================================================================
+
+/** Base submission data shared by all post types */
+export interface SubmissionBase {
+  /** Nostr event ID */
+  id: string
+  /** Author public key */
+  pubkey: string
+  /** Unix timestamp (seconds) */
+  created_at: number
+  /** Event kind (1111) */
+  kind: typeof SUBMISSION_KINDS.SUBMISSION
+  /** Raw event tags */
+  tags: string[][]
+  /** Submission title (required) */
+  title: string
+  /** Post type discriminator */
+  postType: SubmissionType
+  /** Community reference (a-tag format) */
+  communityRef?: string
+  /** Hashtags/topics */
+  hashtags: string[]
+  /** Whether marked NSFW */
+  nsfw: boolean
+  /** Flair/label for the post */
+  flair?: string
+}
+
+/** Link submission with URL and preview */
+export interface LinkSubmission extends SubmissionBase {
+  postType: 'link'
+  /** External URL */
+  url: string
+  /** Link preview metadata */
+  preview?: LinkPreview
+  /** Optional body/description */
+  body?: string
+}
+
+/** Media submission with attachments */
+export interface MediaSubmission extends SubmissionBase {
+  postType: 'media'
+  /** Primary media attachment */
+  media: MediaAttachment
+  /** Additional media attachments (gallery) */
+  gallery?: MediaAttachment[]
+  /** Caption/description */
+  body?: string
+}
+
+/** Self/text submission */
+export interface SelfSubmission extends SubmissionBase {
+  postType: 'self'
+  /** Markdown body content */
+  body: string
+}
+
+/** Union type for all submission types */
+export type Submission = LinkSubmission | MediaSubmission | SelfSubmission
+
+// ============================================================================
+// Voting & Scoring
+// ============================================================================
+
+/** Vote counts and user state for a submission */
+export interface SubmissionVotes {
+  /** Total upvotes */
+  upvotes: number
+  /** Total downvotes */
+  downvotes: number
+  /** Net score (upvotes - downvotes) */
+  score: number
+  /** Current user's vote */
+  userVote: VoteType
+  /** User's vote event ID (for deletion) */
+  userVoteId?: string
+}
+
+/** Ranking scores for sorting */
+export interface SubmissionRanking {
+  /** Hot rank score (activity + recency) */
+  hotRank: number
+  /** Controversy rank (balanced voting) */
+  controversyRank: number
+  /** Scaled rank (amplifies smaller communities) */
+  scaledRank: number
+}
+
+// ============================================================================
+// Full Submission with Metadata
+// ============================================================================
+
+/** Complete submission with all associated data */
+export interface SubmissionWithMeta extends Submission {
+  /** Vote counts and user state */
+  votes: SubmissionVotes
+  /** Ranking scores */
+  ranking: SubmissionRanking
+  /** Total comment count */
+  commentCount: number
+  /** Whether the submission is saved by current user */
+  isSaved: boolean
+  /** Whether hidden by current user */
+  isHidden: boolean
+  /** Approval status in moderated community */
+  approvalStatus: 'pending' | 'approved' | 'rejected' | null
+}
+
+// ============================================================================
+// Comments
+// ============================================================================
+
+/** Comment on a submission (also kind 1111) */
+export interface SubmissionComment {
+  /** Nostr event ID */
+  id: string
+  /** Author public key */
+  pubkey: string
+  /** Unix timestamp */
+  created_at: number
+  /** Comment text content */
+  content: string
+  /** Root submission ID */
+  rootId: string
+  /** Direct parent ID (submission or comment) */
+  parentId: string
+  /** Depth in comment tree (0 = top-level) */
+  depth: number
+  /** Child comments */
+  replies: SubmissionComment[]
+  /** Vote data */
+  votes: SubmissionVotes
+  /** Whether collapsed in UI */
+  isCollapsed?: boolean
+}
+
+// ============================================================================
+// Community Types (NIP-72)
+// ============================================================================
+
+/** Community moderator */
+export interface CommunityModerator {
+  pubkey: string
+  relay?: string
+  role: 'moderator' | 'admin'
+}
+
+/** Community definition (kind 34550) */
+export interface Community {
+  /** Unique identifier (d-tag) */
+  id: string
+  /** Creator public key */
+  pubkey: string
+  /** Display name */
+  name: string
+  /** Description/about */
+  description?: string
+  /** Banner/header image URL */
+  image?: string
+  /** Icon/avatar URL */
+  icon?: string
+  /** List of moderators */
+  moderators: CommunityModerator[]
+  /** Rules (markdown) */
+  rules?: string
+  /** Preferred relays */
+  relays: {
+    author?: string
+    requests?: string
+    approvals?: string
+  }
+  /** Tags/topics */
+  tags: string[]
+  /** Whether posts require approval */
+  requiresApproval: boolean
+  /** Creation timestamp */
+  created_at: number
+}
+
+/** Community reference (a-tag format) */
+export interface CommunityRef {
+  /** "34550" */
+  kind: string
+  /** Community creator pubkey */
+  pubkey: string
+  /** Community d-tag identifier */
+  identifier: string
+  /** Relay hint */
+  relay?: string
+}
+
+// ============================================================================
+// Form Types (for creating/editing)
+// ============================================================================
+
+/** Form data for creating a link submission */
+export interface LinkSubmissionForm {
+  postType: 'link'
+  title: string
+  url: string
+  body?: string
+  communityRef?: string
+  nsfw?: boolean
+  flair?: string
+}
+
+/** Form data for creating a media submission */
+export interface MediaSubmissionForm {
+  postType: 'media'
+  title: string
+  /** File to upload, or URL if already uploaded */
+  media: File | string
+  body?: string
+  alt?: string
+  communityRef?: string
+  nsfw?: boolean
+  flair?: string
+}
+
+/** Form data for creating a self/text submission */
+export interface SelfSubmissionForm {
+  postType: 'self'
+  title: string
+  body: string
+  communityRef?: string
+  nsfw?: boolean
+  flair?: string
+}
+
+/** Union type for submission forms */
+export type SubmissionForm = LinkSubmissionForm | MediaSubmissionForm | SelfSubmissionForm
+
+// ============================================================================
+// Feed Configuration
+// ============================================================================
+
+/** Configuration for fetching submissions */
+export interface SubmissionFeedConfig {
+  /** Community to filter by (optional, null = all) */
+  community?: CommunityRef | null
+  /** Sort order */
+  sort: SortType
+  /** Time range for "top" sort */
+  timeRange?: TimeRange
+  /** Filter by post type */
+  postTypes?: SubmissionType[]
+  /** Include NSFW content */
+  includeNsfw: boolean
+  /** Maximum submissions to fetch */
+  limit: number
+  /** Author filter */
+  authors?: string[]
+  /** Hashtag filter */
+  hashtags?: string[]
+}
+
+// ============================================================================
+// Helper Functions
+// ============================================================================
+
+/**
+ * Parse an 'a' tag into a CommunityRef
+ * Format: "34550:<pubkey>:<identifier>"
+ */
+export function parseCommunityRef(aTag: string, relay?: string): CommunityRef | null {
+  const parts = aTag.split(':')
+  if (parts.length < 3 || parts[0] !== '34550') {
+    return null
+  }
+  return {
+    kind: parts[0],
+    pubkey: parts[1],
+    identifier: parts.slice(2).join(':'), // identifier may contain colons
+    relay
+  }
+}
+
+/**
+ * Format a CommunityRef back to 'a' tag format
+ */
+export function formatCommunityRef(ref: CommunityRef): string {
+  return `${ref.kind}:${ref.pubkey}:${ref.identifier}`
+}
+
+/**
+ * Extract domain from URL
+ */
+export function extractDomain(url: string): string {
+  try {
+    const parsed = new URL(url)
+    return parsed.hostname.replace(/^www\./, '')
+  } catch {
+    return url
+  }
+}
+
+/**
+ * Classify media type from MIME type
+ */
+export function classifyMediaType(mimeType?: string): MediaType {
+  if (!mimeType) return 'other'
+  if (mimeType.startsWith('image/')) return 'image'
+  if (mimeType.startsWith('video/')) return 'video'
+  if (mimeType.startsWith('audio/')) return 'audio'
+  return 'other'
+}
+
+/**
+ * Parse imeta tag into MediaAttachment
+ * Format: ["imeta", "url <url>", "m <mime>", "dim <WxH>", ...]
+ */
+export function parseImetaTag(tag: string[]): MediaAttachment | null {
+  if (tag[0] !== 'imeta') return null
+
+  const attachment: MediaAttachment = { url: '' }
+
+  for (let i = 1; i < tag.length; i++) {
+    const [key, ...valueParts] = tag[i].split(' ')
+    const value = valueParts.join(' ')
+
+    switch (key) {
+      case 'url':
+        attachment.url = value
+        break
+      case 'm':
+        attachment.mimeType = value
+        break
+      case 'dim':
+        attachment.dimensions = value
+        const [w, h] = value.split('x').map(Number)
+        if (!isNaN(w)) attachment.width = w
+        if (!isNaN(h)) attachment.height = h
+        break
+      case 'blurhash':
+        attachment.blurhash = value
+        break
+      case 'alt':
+        attachment.alt = value
+        break
+      case 'x':
+        attachment.hash = value
+        break
+      case 'size':
+        attachment.size = parseInt(value, 10)
+        break
+      case 'thumb':
+        attachment.thumbnail = value
+        break
+      case 'fallback':
+        attachment.fallbacks = attachment.fallbacks || []
+        attachment.fallbacks.push(value)
+        break
+    }
+  }
+
+  return attachment.url ? attachment : null
+}
+
+/**
+ * Build imeta tag from MediaAttachment
+ */
+export function buildImetaTag(media: MediaAttachment): string[] {
+  const tag = ['imeta']
+
+  tag.push(`url ${media.url}`)
+  if (media.mimeType) tag.push(`m ${media.mimeType}`)
+  if (media.dimensions) tag.push(`dim ${media.dimensions}`)
+  else if (media.width && media.height) tag.push(`dim ${media.width}x${media.height}`)
+  if (media.blurhash) tag.push(`blurhash ${media.blurhash}`)
+  if (media.alt) tag.push(`alt ${media.alt}`)
+  if (media.hash) tag.push(`x ${media.hash}`)
+  if (media.size) tag.push(`size ${media.size}`)
+  if (media.thumbnail) tag.push(`thumb ${media.thumbnail}`)
+  media.fallbacks?.forEach(fb => tag.push(`fallback ${fb}`))
+
+  return tag
+}
+
+// ============================================================================
+// Ranking Algorithms
+// ============================================================================
+
+/** Epoch for hot rank calculation (Unix timestamp) */
+const HOT_RANK_EPOCH = 1134028003 // Dec 8, 2005 (Reddit's epoch)
+
+/**
+ * Calculate hot rank score (Reddit/Lemmy style)
+ * Higher scores for posts with more upvotes that are newer
+ */
+export function calculateHotRank(score: number, createdAt: number): number {
+  const order = Math.log10(Math.max(Math.abs(score), 1))
+  const sign = score > 0 ? 1 : score < 0 ? -1 : 0
+  const seconds = createdAt - HOT_RANK_EPOCH
+  return sign * order + seconds / 45000
+}
+
+/**
+ * Calculate controversy rank
+ * Higher scores for posts with balanced up/down votes
+ */
+export function calculateControversyRank(upvotes: number, downvotes: number): number {
+  const total = upvotes + downvotes
+  if (total === 0) return 0
+
+  const magnitude = Math.pow(total, 0.8)
+  const balance = Math.min(upvotes, downvotes) / Math.max(upvotes, downvotes, 1)
+
+  return magnitude * balance
+}
+
+/**
+ * Calculate confidence score (Wilson score interval lower bound)
+ * Used for "best" comment sorting
+ */
+export function calculateConfidence(upvotes: number, downvotes: number): number {
+  const n = upvotes + downvotes
+  if (n === 0) return 0
+
+  const z = 1.96 // 95% confidence
+  const p = upvotes / n
+
+  const left = p + (z * z) / (2 * n)
+  const right = z * Math.sqrt((p * (1 - p) + (z * z) / (4 * n)) / n)
+  const under = 1 + (z * z) / n
+
+  return (left - right) / under
+}