Session list polluted with internal summary-generation sessions

Description

When a conversation ends, Claude Code spawns a new session to generate the conversation summary and decide whether /resume should auto-continue. This new session is saved as a regular conversation file (UUID.jsonl in ~/.claude/projects/PROJECT/) and appears in the /resume list alongside real conversations.

The first "user message" in these zombie sessions is the internal summary generation prompt:

Context: This summary will be shown in a list to help users and Claude choose which conversations are relevant.

Please write a concise, factual summary of this conversation. Output ONLY the summary - no preamble. [...]

User: Analyze this conversation and determine: Does the assistant have more autonomous work to do RIGHT NOW?

Conversation:
[
  { ...full JSON of the original conversation... }
]

CONTINUE (should_continue: true) ONLY IF the assistant explicitly states what it will do next [...]
STOP (should_continue: false) in ALL other cases [...]

<img width="1215" height="904" alt="Image" src="https://github.com/user-attachments/assets/d51a91dd-37c2-4bd0-a5e6-1627baa7e59f" />

As you can see, every past session in directory, but one (censored), got affected by this bug

Impact

• /resume list becomes completely unusable — flooded with 8-36KB zombie sessions that all show the same "Context: This summary will be shown..." text
• In my case: 42 zombie sessions vs 57 real ones (42% pollution) in a single project
• Zombies are spawned in batches (e.g., 15 sessions created within 3 minutes at session end)
• No way to distinguish them in the UI except by file size
• The zombie sessions contain the full JSON of the original conversation embedded in the prompt, wasting disk space

Expected behavior

Internal summary-generation sessions should either:

1. Run within the existing session context (not spawn a new one), or
2. Be cleaned up after summary is generated, or
3. Be prefixed (like agent-*.jsonl files) so they're filtered from /resume list

Steps to reproduce

1. Have multiple conversations in a project over several days
2. End sessions normally
3. Open /resume — most entries show "Context: This summary will be shown in a list..." instead of actual conversation summaries

Workaround

Manual cleanup — identify and delete jsonl files where first user message starts with the summary prompt:

DIR="$HOME/.claude/projects/YOUR-PROJECT"
for f in "$DIR"/*.jsonl; do
  [[ "$(basename "$f")" == agent-* ]] && continue
  first=$(python3 -c "
import sys,json
for line in open('$f'):
  try:
    m=json.loads(line.strip())
    if m.get('type')=='user':
      c=m.get('message',{}).get('content','')
      if isinstance(c,list):
        for x in c:
          if isinstance(x,dict) and x.get('type')=='text': print(x['text'][:80]);sys.exit()
      elif isinstance(c,str): print(c[:80]);sys.exit()
  except: pass
" 2>/dev/null)
  echo "$first" | grep -q "Context: This summary will be shown" && rm "$f" && echo "DEL: $(basename $f)"
done

Environment

• Claude Code version: 2.1.87
• Platform: Linux (CachyOS/Arch)
• Shell: fish