"""Compact view of a trajectory row: role, tool names, first N chars of each message."""
import json

def one_line(s, n=150):
    s = (s or "").replace("\r", "").replace("\n", "⏎ ")
    return s[:n] + ("…" if len(s) > n else "")

def compact_view(row, n=150, head=8, tail=5):
    msgs = row["messages"]
    lines = [f"id={row['id']} session={row['session_id']} role={row['agent_role']} thread={row['thread_source']} model={row['model']}/{row['effort']} "
             f"task_source={row['task_source']} seg={row['segment']}/{row['segments_total']} calls={row['n_tool_calls']} failed={row['n_failed_calls']} flags={row['flags']} msgs={len(msgs)}"]
    idx = list(range(len(msgs)))
    if len(msgs) > head + tail:
        show = idx[:head] + [None] + idx[-tail:]
    else:
        show = idx
    for i in show:
        if i is None:
            lines.append(f"   … {len(msgs) - head - tail} more messages …")
            continue
        m = msgs[i]
        r = m["role"]
        if r == "assistant":
            tcs = m.get("tool_calls") or []
            names = ",".join(tc["function"]["name"] for tc in tcs)
            body = one_line(m.get("content"), n) if m.get("content") else "(no text)"
            tag = f"assistant[calls: {names}]" if tcs else "assistant"
            lines.append(f"  [{i}] {tag}: {body}")
            for tc in tcs[:2]:
                lines.append(f"        ↳ {tc['function']['name']}({one_line(tc['function']['arguments'], n)})")
            if len(tcs) > 2:
                lines.append(f"        ↳ … +{len(tcs)-2} more calls")
        elif r == "tool":
            lines.append(f"  [{i}] tool({m['tool_call_id'][-8:]}): {one_line(m['content'], n)}")
        else:
            lines.append(f"  [{i}] {r}: {one_line(m['content'], n)}")
    return "\n".join(lines)