fix-stuck-session

name	fix-stuck-session
description	Fix a Claude Code session stuck in an API 400 loop about thinking blocks that cannot be modified. Backs up the session JSONL, strips all thinking/redacted_thinking blocks, and preserves everything else.
license	MIT
metadata	{"author":"lifeodyssey","version":"1.0.0"}

Fix Stuck Session — Thinking Block Remover

When a Claude Code session hits a 400 error loop about "thinking blocks cannot be modified", the cause is stale thinking/redacted_thinking blocks in the session JSONL file being replayed back to the API. This skill strips them.

Steps

1. Locate the stuck session

Session files live at ~/.claude/projects/<project-dir>/<session-id>.jsonl where <project-dir> is the working directory path with / replaced by -.

Run this to find the most recently modified session for the current project:

PROJECT_DIR=$(echo "$PWD" | sed 's|/|-|g')
SESSION_DIR=~/.claude/projects/"$PROJECT_DIR"
LATEST=$(ls -t "$SESSION_DIR"/*.jsonl 2>/dev/null | head -1)
echo "Latest session: $LATEST"

If the user specifies a session ID, use that instead. If they say "previous session" or "stuck session", use the most recent .jsonl that is NOT the current session (skip the newest, take the second).

2. Verify it has thinking blocks

python3 -c "
import json, sys
path = '$LATEST'
t = r = 0
with open(path) as f:
    for line in f:
        if not line.strip(): continue
        obj = json.loads(line)
        if obj.get('type') == 'assistant':
            for b in obj.get('message',{}).get('content',[]):
                if b.get('type') == 'thinking': t += 1
                elif b.get('type') == 'redacted_thinking': r += 1
print(f'thinking: {t}, redacted_thinking: {r}')
if t + r == 0:
    print('No thinking blocks found — this session may not be the stuck one.')
    sys.exit(1)
"

If zero thinking blocks, ask the user to confirm the session or check a different one.

3. Backup and strip

cp "$LATEST" "${LATEST}.bak"
python3 -c "
import json

path = '${LATEST}'
lines = []
with open(path) as f:
    for line in f:
        line = line.rstrip('\n')
        if not line:
            lines.append(line)
            continue
        obj = json.loads(line)
        if obj.get('type') == 'assistant':
            msg = obj.get('message', {})
            content = msg.get('content', [])
            filtered = [b for b in content if b.get('type') not in ('thinking', 'redacted_thinking')]
            if not filtered:
                filtered = [{'type': 'text', 'text': '[thinking omitted]'}]
            msg['content'] = filtered
            obj['message'] = msg
        lines.append(json.dumps(obj, ensure_ascii=False))

with open(path, 'w') as f:
    for line in lines:
        f.write(line + '\n')
"

4. Verify the fix

python3 -c "
import json
path = '${LATEST}'
total_lines = thinking = 0
with open(path) as f:
    for line in f:
        total_lines += 1
        if not line.strip(): continue
        obj = json.loads(line)
        if obj.get('type') == 'assistant':
            for b in obj.get('message',{}).get('content',[]):
                if b.get('type') in ('thinking', 'redacted_thinking'):
                    thinking += 1
print(f'Lines: {total_lines}, Remaining thinking blocks: {thinking}')
assert thinking == 0, 'FAILED: thinking blocks still present'
print('Session cleaned successfully.')
"
echo "Backup saved at: ${LATEST}.bak"

5. Report to user

Tell the user:

• How many thinking blocks were removed
• The session file path
• The backup location
• They can resume the session with claude --resume <session-id> (the UUID from the filename)