Switch from delete+recreate to PUT in-place updates

- Removes flicker caused by delete+recreate pattern
- PUT updates modify post content in-place (smooth)
- Trade-off: Mattermost shows (edited) label, and PUT clears pin status
- Pin+PUT are incompatible in Mattermost API — every PUT clears is_pinned
- Fix pin API calls to use {} body instead of null
- Remove post-replaced event handler (no longer needed)

src/status-box.js

@@ -163,40 +163,13 @@ class StatusBox extends EventEmitter {
     this.metrics.queueDepth = Math.max(0, this.metrics.queueDepth - 1);
 
     try {
-      // Delete + recreate to keep status post at the bottom of the thread
-      // Mattermost clears pin on PUT, and edited posts stay at their original position
-      const postInfo = this._postInfo.get(postId);
-      if (postInfo) {
-        try {
-          await this._httpRequest('DELETE', `/api/v4/posts/${postId}`, null);
-        } catch (_delErr) {
-          // If delete fails, fall back to PUT
-        }
-        const body = { channel_id: postInfo.channelId, message: this._truncate(text) };
-        if (postInfo.rootId) body.root_id = postInfo.rootId;
-        const newPost = await this._httpRequest('POST', '/api/v4/posts', body);
-        // Update tracking
-        this._postInfo.set(newPost.id, postInfo);
-        this._postInfo.delete(postId);
-        // Update throttle state key
-        const newState = this._throttleState.get(postId);
-        if (newState) {
-          this._throttleState.delete(postId);
-          this._throttleState.set(newPost.id, { pending: null, timer: null, lastFiredAt: Date.now(), resolvers: [] });
-        }
-        // Notify caller of new post ID
-        this.emit('post-replaced', postId, newPost.id);
-        this.metrics.updatesSent++;
-        resolvers.forEach(({ resolve }) => resolve());
-      } else {
-        // Fallback: regular PUT update
-        await this._apiCallWithRetry('PUT', `/api/v4/posts/${postId}`, {
-          id: postId,
-          message: this._truncate(text),
-        });
-        this.metrics.updatesSent++;
-        resolvers.forEach(({ resolve }) => resolve());
-      }
+      // In-place PUT update — no delete+recreate, no flicker
+      await this._apiCallWithRetry('PUT', `/api/v4/posts/${postId}`, {
+        id: postId,
+        message: this._truncate(text),
+      });
+      this.metrics.updatesSent++;
+      resolvers.forEach(({ resolve }) => resolve());
     } catch (err) {
       this.metrics.updatesFailed++;
       resolvers.forEach(({ reject }) => reject(err));

src/watcher-manager.js

@@ -240,6 +240,14 @@ async function startDaemon() {
         const initialText = buildInitialText(agentId, sessionKey);
         postId = await sharedStatusBox.createPost(channelId, initialText, rootPostId);
         logger.info({ sessionKey, postId, channelId }, 'Created status box');
+
+        // Auto-pin the status post so it's always visible
+        try {
+          await sharedStatusBox._apiCall('POST', '/api/v4/posts/' + postId + '/pin', {});
+          logger.debug({ sessionKey, postId }, 'Status post pinned');
+        } catch (pinErr) {
+          logger.warn({ sessionKey, err: pinErr }, 'Failed to pin status post');
+        }
       } catch (err) {
         logger.error({ sessionKey, err }, 'Failed to create status post');
         globalMetrics.lastError = err.message;
@@ -282,18 +290,6 @@ async function startDaemon() {
     logger.debug({ sessionKey }, 'Session removed from sessions.json');
   });
 
-  // ---- Post Replaced (delete+recreate) ----
-  sharedStatusBox.on('post-replaced', (oldPostId, newPostId) => {
-    // Update activeBoxes to point to new post ID
-    for (var entry of activeBoxes.entries()) {
-      if (entry[1].postId === oldPostId) {
-        entry[1].postId = newPostId;
-        logger.debug({ sessionKey: entry[0], oldPostId, newPostId }, 'Post replaced (delete+recreate)');
-        break;
-      }
-    }
-  });
-
   // ---- Session Update (from watcher) ----
   watcher.on('session-update', (sessionKey, state) => {
     const box = activeBoxes.get(sessionKey);
@@ -345,7 +341,7 @@ async function startDaemon() {
 
     // Unpin the status post when session is done
     try {
-      await sharedStatusBox._apiCall('POST', `/api/v4/posts/${box.postId}/unpin`, null);
+      await sharedStatusBox._apiCall('POST', `/api/v4/posts/${box.postId}/unpin`, {});
       logger.debug({ sessionKey, postId: box.postId }, 'Status post unpinned');
     } catch (unpinErr) {
       logger.warn({ sessionKey, err: unpinErr }, 'Failed to unpin status post');