feat: add conversation image previews and sharing

src/services/media-library-exchange.ts

@@ -28,6 +28,11 @@ export type MediaExchangeResult =
   | { kind: 'retryable'; assetId: string; requestKind: MediaRequestKind }
   | { kind: 'human-required'; reason: string; remoteSent?: boolean };
 
+export interface ShareableMediaLibraryAssets {
+  requestKind: MediaRequestKind | null;
+  assets: MediaLibraryAsset[];
+}
+
 /** Detects inbound requests, reserves an unused asset, then sends image before reciprocal text. */
 export class MediaLibraryExchangeService {
   constructor(
@@ -59,6 +64,35 @@ export class MediaLibraryExchangeService {
     conversationId: string,
     incomingKey: string,
     incomingText: string,
+  ): Promise<MediaExchangeResult> {
+    return this.handleRequest(conversationId, incomingKey, incomingText);
+  }
+
+  listShareable(conversationId: string, incomingText: string): ShareableMediaLibraryAssets {
+    const prior = this.repository.listConversationSends(this.accountId, conversationId);
+    const requestKind = detectMediaRequest(incomingText, prior);
+    if (!requestKind) return { requestKind: null, assets: [] };
+    const used = new Set(prior.map((item) => item.assetId));
+    return {
+      requestKind,
+      assets: this.pickEligible(this.repository.listEligible(), used, requestKind, prior),
+    };
+  }
+
+  async handleSelected(
+    conversationId: string,
+    incomingKey: string,
+    incomingText: string,
+    assetId: string,
+  ): Promise<MediaExchangeResult> {
+    return this.handleRequest(conversationId, incomingKey, incomingText, assetId);
+  }
+
+  private async handleRequest(
+    conversationId: string,
+    incomingKey: string,
+    incomingText: string,
+    selectedAssetId?: string,
   ): Promise<MediaExchangeResult> {
     const prior = this.repository.listConversationSends(this.accountId, conversationId);
     const requestKind = detectMediaRequest(incomingText, prior);
@@ -66,6 +100,12 @@ export class MediaLibraryExchangeService {
     if (this.dryRun) return { kind: 'dry-run', requestKind };
 
     let send = this.repository.getSend(this.accountId, conversationId, incomingKey);
+    if (send && selectedAssetId && send.assetId !== selectedAssetId) {
+      return { kind: 'human-required', reason: 'A different library image is already reserved for this request.' };
+    }
+    if (send?.status === 'sent' && send.matrixTextEventId === 'unconfirmed') {
+      return { kind: 'human-required', reason: 'The image was sent, but the reciprocal text was not confirmed.', remoteSent: true };
+    }
     if (send?.status === 'sent') return { kind: 'sent', assetId: send.assetId, requestKind: send.requestKind };
     if (send?.status === 'failed' || send?.status === 'superseded') {
       return { kind: 'human-required', reason: 'A previous media send for this request failed or became uncertain.' };
@@ -73,7 +113,13 @@ export class MediaLibraryExchangeService {
     if (!send) {
       const used = new Set(prior.map((item) => item.assetId));
       const eligible = this.pickEligible(this.repository.listEligible(), used, requestKind, prior);
-      for (const asset of shuffled(eligible, this.random)) {
+      const candidates = selectedAssetId
+        ? eligible.filter((asset) => asset.id === selectedAssetId)
+        : shuffled(eligible, this.random);
+      if (selectedAssetId && candidates.length === 0) {
+        return { kind: 'human-required', reason: 'That library image is disabled, already used, or does not match the current request.' };
+      }
+      for (const asset of candidates) {
         send = this.repository.tryReserve(asset.id, this.accountId, conversationId, incomingKey, requestKind) ?? undefined;
         if (send) break;
       }