feat(attachments): extend stage/read spans and unlink on delete

attachment.stage reports stagedCount and remainingStagingCapacity;
attachment.read includes activeChannelId; attachment.unlink runs before
message removal when attachments were linked.

Co-authored-by: Cursor <[email protected]>

README.md

@@ -183,6 +183,8 @@ Expose a single `EventEmitter` API the UI drives over IPC (`apps/pearcord/index.
 
 **v0.8.499 (Phase 536):** Compliance/audit spans extend — `audit.append`/`audit.export`/`compliance.snapshot` end metadata (`spanKind`, `activeChannelId`). UI compliance panel compositor wrappers, audit row `lastAuditRowId` + roving `tabindex`, clipboard compliance busy flags. Bundle: `npm run test:phase536-compliance`. See [COMPLIANCE.md](../../docs/COMPLIANCE.md), [AUDIT_LOG.md](../../docs/AUDIT_LOG.md).
 
+**v0.8.519 (Phase 556):** Attachment spans extend — `attachment.stage` `stagedCount`/`remainingStagingCapacity`; `attachment.read` `activeChannelId`; `attachment.unlink` on delete. UI split attachment panels; `#attachment-panel-live`. Bundle: `npm run test:phase556-attachments`. See [ATTACHMENTS.md](../../docs/ATTACHMENTS.md).
+
 **v0.8.518 (Phase 555):** Reaction spans extend — `reaction.toggle` `messageReactionCount`/`activeChannelId`; `reaction.list` `rowCount`/`messageCount`; `reaction.clear` on delete via `clearReactionsForMessage`. UI split reaction pills/quick-react/picker chrome/live panels; `#reaction-panel-live`. Bundle: `npm run test:phase555-reactions`. See [REACTIONS.md](../../docs/REACTIONS.md).
 
 **v0.8.517 (Phase 554):** Messaging spans extend — `message.send` `channelMessageCount`/`remainingCharCapacity`; `message.edit` `editAgeMs`; `message.delete` `meshFanout`. UI split messaging panels; `#messaging-panel-live`. Bundle: `npm run test:phase554-messaging`. See [MESSAGING.md](../../docs/MESSAGING.md).

index.js

@@ -5295,6 +5295,9 @@ class PearcordPlatform extends EventEmitter {
         authorId: user.id
       })
       const rowMime = row?.mimeType || resolvedMime
+      const stagedCount = this.attachments?.countStagedForChannel
+        ? await this.attachments.countStagedForChannel(this.activeChannelId)
+        : 0
       span.end({
         spanKind: 'attachment.stage',
         attachmentId: row?.id,
@@ -5304,7 +5307,10 @@ class PearcordPlatform extends EventEmitter {
         mimeType: rowMime,
         byteLength,
         filenameLen: String(filename || '').length,
-        isImage: String(rowMime || '').startsWith('image/')
+        isImage: String(rowMime || '').startsWith('image/'),
+        stagedCount,
+        remainingStagingCapacity: Math.max(0, 10 - stagedCount),
+        activeChannelId: this.activeChannelId
       })
       return row
     } catch (err) {
@@ -12927,6 +12933,7 @@ class PearcordPlatform extends EventEmitter {
         reactionCount = rows.filter((r) => r.messageId === messageId).length
       }
       let clearedReactionCount = 0
+      let unlinkedAttachmentCount = 0
       if (this.messages?.clearReactionsForMessage && reactionCount > 0) {
         const clearSpan = this.log.time('reaction.clear', {
           spanKind: 'reaction.clear',
@@ -12954,6 +12961,33 @@ class PearcordPlatform extends EventEmitter {
           clearSpan.fail(err)
         }
       }
+      if (hadAttachments && this.attachments?.unlinkMessage) {
+        const unlinkSpan = this.log.time('attachment.unlink', {
+          spanKind: 'attachment.unlink',
+          messageId,
+          guildId,
+          channelId
+        })
+        try {
+          unlinkedAttachmentCount = await this.attachments.unlinkMessage(messageId)
+          unlinkSpan.end({
+            spanKind: 'attachment.unlink',
+            messageId,
+            guildId,
+            channelId,
+            unlinkedCount: unlinkedAttachmentCount,
+            activeChannelId: this.activeChannelId
+          })
+        } catch (err) {
+          this.log.error('attachment.unlink error', {
+            messageId,
+            guildId,
+            channelId,
+            error: err?.message || String(err)
+          })
+          unlinkSpan.fail(err)
+        }
+      }
       await this.messages.remove(messageId)
       const payload = {
         id: messageId,
@@ -12970,6 +13004,7 @@ class PearcordPlatform extends EventEmitter {
         channelId,
         contentLength,
         hadAttachments,
+        unlinkedAttachmentCount,
         hadReactions: reactionCount > 0,
         reactionCount,
         wasOwn: existing?.authorId === this.identity?.user?.id,