Daily Reading for 2026-04-19 William Glaser 2026.04.19 1 min to read daily-reading Home / Daily Reading / Daily Reading for 2026-04-19 Security Microsoft Security Blog Programming Simon Willison’s Weblog Daily Reading for 2026-04-19 Security Microsoft Security Blog Cross‑tenant helpdesk impersonation to data exfiltration: A human-operated intrusion playbook Programming Simon Willison’s Weblog Changes in the system prompt between Claude Opus 4.6 and 4.7 Claude system prompts as a git timeline