Add session-end-log hook with per-session token tally

既有 Stop 钩子 token-stats-hook 记的是跨会话累计快照, 无法区分"这次会话
用了多少"; session-end-log 在 SessionEnd 时按 session_id 解析本次 transcript
做单会话统计, 产出一行可回溯的索引写入 ~/.claude/log.md, 方便事后盘点
哪场会话烧了哪些 token。Python 写零依赖, Ubuntu 自带 python3 免构建。

hooks/session-end-log/README.md

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+# session-end-log
+
+Claude Code SessionEnd hook：每次会话结束时在 `~/.claude/log.md` 追加一行元数据 + token 用量。
+
+用 Python 编写，零依赖（Ubuntu 自带 `python3`）。
+
+## 输出格式
+
+```
+- 2026-04-21T00:55:30 | session=353cbdc1 | cwd=/home/charles | reason=clear | tokens=total:592.7k in:39 out:3.7k cache_r:558.2k cache_w:30.7k
+```
+
+字段：
+- `reason`：`clear` / `logout` / `resume` / `prompt_input_exit` 之一
+- `session`：session_id 前 8 位
+- `tokens`：读取该会话的 transcript（`~/.claude/projects/<slug>/<sid>.jsonl`）按 `type=assistant` 的 usage 累加；transcript 读不到时降级为 `tokens=unavailable`，不阻塞会话退出
+
+## 安装
+
+```bash
+mkdir -p ~/.claude/hooks
+cp hooks/session-end-log/session-end-log.py ~/.claude/hooks/
+chmod +x ~/.claude/hooks/session-end-log.py
+```
+
+然后在 `~/.claude/settings.json` 的 `hooks` 下加入（与现有 `Stop` 等共存）：
+
+```json
+{
+  "hooks": {
+    "SessionEnd": [
+      {
+        "hooks": [
+          {
+            "type": "command",
+            "command": "python3 ~/.claude/hooks/session-end-log.py 2>/dev/null || true"
+          }
+        ]
+      }
+    ]
+  }
+}
+```
+
+## 测试
+
+```bash
+echo '{"cwd":"/home/charles","reason":"test","session_id":"<real-session-id>"}' \
+    | python3 ~/.claude/hooks/session-end-log.py
+tail -1 ~/.claude/log.md
+```

hooks/session-end-log/session-end-log.py

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+#!/usr/bin/env python3
+"""SessionEnd hook: append one metadata + token-usage line to ~/.claude/log.md."""
+import json, sys, pathlib
+from datetime import datetime
+
+try:
+    data = json.load(sys.stdin)
+except Exception:
+    data = {}
+
+ts = datetime.now().strftime("%Y-%m-%dT%H:%M:%S")
+cwd = data.get("cwd", "?")
+reason = data.get("reason", "?")
+sid = data.get("session_id") or "?"
+sid_short = sid[:8]
+
+
+def find_transcript():
+    tp = data.get("transcript_path")
+    if tp and pathlib.Path(tp).exists():
+        return pathlib.Path(tp)
+    if cwd == "?" or sid == "?":
+        return None
+    slug = cwd.replace("/", "-")
+    candidate = pathlib.Path.home() / ".claude" / "projects" / slug / f"{sid}.jsonl"
+    return candidate if candidate.exists() else None
+
+
+def sum_tokens(path):
+    totals = {"input": 0, "output": 0, "cache_read": 0, "cache_write": 0}
+    try:
+        with path.open() as f:
+            for line in f:
+                try:
+                    rec = json.loads(line)
+                except Exception:
+                    continue
+                if rec.get("type") != "assistant":
+                    continue
+                u = rec.get("message", {}).get("usage") or {}
+                totals["input"] += u.get("input_tokens", 0)
+                totals["output"] += u.get("output_tokens", 0)
+                totals["cache_read"] += u.get("cache_read_input_tokens", 0)
+                totals["cache_write"] += u.get("cache_creation_input_tokens", 0)
+    except Exception:
+        pass
+    return totals
+
+
+def fmt(n):
+    if n >= 1_000_000:
+        return f"{n/1_000_000:.1f}M"
+    if n >= 1_000:
+        return f"{n/1_000:.1f}k"
+    return str(n)
+
+
+tpath = find_transcript()
+if tpath:
+    t = sum_tokens(tpath)
+    total = sum(t.values())
+    tok_str = (
+        f"tokens=total:{fmt(total)} "
+        f"in:{fmt(t['input'])} out:{fmt(t['output'])} "
+        f"cache_r:{fmt(t['cache_read'])} cache_w:{fmt(t['cache_write'])}"
+    )
+else:
+    tok_str = "tokens=unavailable"
+
+line = f"- {ts} | session={sid_short} | cwd={cwd} | reason={reason} | {tok_str}\n"
+log = pathlib.Path.home() / ".claude" / "log.md"
+if not log.exists():
+    log.write_text("# Session Log\n\n")
+with log.open("a") as f:
+    f.write(line)