何が変わり、何をすべきかが伝わる changelog entry を書く

{
  "version": "1.4.0",
  "date": "2026-09-20",
  "changes": [
    {
      "area": "Export path",
      "change": "Default CSV export folder changed from reports/ to outputs/reports/.",
      "action": "Update scripts or shortcuts that expect reports/."
    },
    {
      "area": "Config key",
      "change": "Configuration key report_dir was renamed to output_dir.",
      "action": "Rename report_dir to output_dir before the next run."
    },
    {
      "area": "Validation",
      "change": "Empty customer_id values now stop export instead of being written as blank cells.",
      "action": "Fix blank customer_id values before rerunning failed exports."
    }
  ],
  "checks": [
    "Confirm a test export appears under outputs/reports/.",
    "Confirm the configuration uses output_dir.",
    "Confirm a row with a blank customer_id stops with a validation error."
  ]
}

Version 1.4.0 - 2026-09-20

What changed
- Export path: Default CSV export folder changed from reports/ to outputs/reports/.
- Config key: Configuration key report_dir was renamed to output_dir.
- Validation: Empty customer_id values now stop export instead of being written as blank cells.

What you need to do
- Update scripts or shortcuts that expect reports/.
- Rename report_dir to output_dir before the next run.
- Fix blank customer_id values before rerunning failed exports.

Check after updating
- Confirm a test export appears under outputs/reports/.
- Confirm the configuration uses output_dir.
- Confirm a row with a blank customer_id stops with a validation error.

import json
from pathlib import Path

SOURCE = Path("release_notes.json")
OUTPUT_DIR = Path("outputs") / "useful_changelog_result"
OUTPUT = OUTPUT_DIR / "CHANGELOG_ENTRY.txt"


def require_text(value, name):
    if not isinstance(value, str) or not value.strip():
        raise ValueError(f"{name} must be a non-empty string.")
    return value.strip()


def main() -> None:
    if not SOURCE.is_file():
        raise FileNotFoundError(f"Source file not found: {SOURCE}")
    if OUTPUT_DIR.exists():
        raise FileExistsError(f"Output folder already exists: {OUTPUT_DIR}")

    with SOURCE.open("r", encoding="utf-8") as stream:
        data = json.load(stream)

    version = require_text(data.get("version"), "version")
    date = require_text(data.get("date"), "date")
    changes = data.get("changes")
    checks = data.get("checks")

    if not isinstance(changes, list) or not changes:
        raise ValueError("changes must be a non-empty list.")
    if not isinstance(checks, list) or not checks:
        raise ValueError("checks must be a non-empty list.")

    change_lines = []
    action_lines = []
    for index, item in enumerate(changes, start=1):
        if not isinstance(item, dict):
            raise ValueError(f"Change {index} must be an object.")
        area = require_text(item.get("area"), f"change {index} area")
        change = require_text(item.get("change"), f"change {index} description")
        action = require_text(item.get("action"), f"change {index} action")
        change_lines.append(f"- {area}: {change}")
        action_lines.append(f"- {action}")

    check_lines = [f"- {require_text(value, 'check')}" for value in checks]

    lines = [
        f"Version {version} - {date}",
        "",
        "What changed",
        *change_lines,
        "",
        "What you need to do",
        *action_lines,
        "",
        "Check after updating",
        *check_lines,
    ]
    text = "\n".join(lines) + "\n"

    if text.count("\nWhat changed\n") != 1:
        raise RuntimeError("Missing What changed section.")
    if text.count("\nWhat you need to do\n") != 1:
        raise RuntimeError("Missing action section.")
    if text.count("\nCheck after updating\n") != 1:
        raise RuntimeError("Missing verification section.")

    bullet_count = sum(line.startswith("- ") for line in lines)
    expected_bullets = len(changes) * 2 + len(checks)
    if bullet_count != expected_bullets:
        raise RuntimeError("Unexpected bullet count.")

    OUTPUT_DIR.parent.mkdir(parents=True, exist_ok=True)
    OUTPUT_DIR.mkdir()
    with OUTPUT.open("x", encoding="utf-8") as stream:
        stream.write(text)

    print(f"Changes: {len(changes)}.")
    print(f"Required actions: {len(action_lines)}.")
    print(f"Verification checks: {len(checks)}.")
    print(f"Total bullets: {bullet_count}.")
    print(f"Output: {OUTPUT.as_posix()}")


if __name__ == "__main__":
    main()

Changes: 3.
Required actions: 3.
Verification checks: 3.
Total bullets: 9.
Output: outputs/useful_changelog_result/CHANGELOG_ENTRY.txt