fix: add channel failure logging to diagnose Discord notification delivery issue

bot.py

@@ -365,6 +365,10 @@ class GravityBot(commands.Bot):
         if project_name in self.project_channels:
             return self.project_channels[project_name]
 
+        if not self.session_category:
+            logger.error(f"[CHANNEL] session_category is None — cannot get channel for project={project_name}")
+            return None
+
         channel_name = self._make_channel_name(project_name)
 
         # 1. Check guild channel cache (NO API call — instant)
@@ -405,6 +409,9 @@ class GravityBot(commands.Bot):
             except discord.errors.Forbidden:
                 logger.error(f"No permission to create channel: {channel_name}")
                 return None
+            except Exception as e:
+                logger.error(f"[CHANNEL] Failed to create channel #{channel_name}: {e}")
+                return None
 
     def _resolve_project(self, conversation_id: str) -> str:
         """Get project name for a conversation. Falls back to default."""
@@ -619,6 +626,7 @@ class GravityBot(commands.Bot):
                     # Show compact auto-approved embed in Discord
                     channel = await self._get_channel(project)
                     if channel:
+                        try:
                             embed = discord.Embed(
                                 title="🤖 자동 승인됨",
                                 description=f"```\n{req.command[:500]}\n```",
@@ -626,6 +634,10 @@ class GravityBot(commands.Bot):
                             )
                             embed.set_footer(text=f"auto-approve | {req.request_id[:12]}")
                             await channel.send(embed=embed)
+                        except Exception as e:
+                            logger.error(f"[AUTO-APPROVE] Discord send failed for {project}: {e}")
+                    else:
+                        logger.warning(f"[AUTO-APPROVE] No Discord channel for project={project} — notification skipped")
                     logger.info(f"Auto-approved: {req.request_id[:12]} project={project} btn_idx={approve_btn_index}")
                     phase1_processed += 1
                     continue
@@ -655,6 +667,8 @@ class GravityBot(commands.Bot):
                     self._sent_commands[req.request_id] = req.command
                     await self._send_approval_request(channel, req)
                     phase1_processed += 1
+                else:
+                    logger.warning(f"[APPROVAL] No Discord channel for project={project} — approval request skipped (rid={req.request_id[:12]})")
 
             # ── Single-pass: handle auto_resolved, expired, and MERGE in one glob ──
             phase2_processed = 0
@@ -894,7 +908,9 @@ class GravityBot(commands.Bot):
 
                     if content or attached_files:
                         channel = await self._get_channel(project)
-                        if channel:
+                        if not channel:
+                            logger.warning(f"[SNAPSHOT] No Discord channel for project={project} — snapshot skipped (len={len(content)})")
+                        elif channel:
                             import io
 
                             # ── Send attached files (from Extension's writeChatSnapshotWithFiles) ──