CWS-96: Session chronicle & self-improvement loop

• Linear: CWS-96
• Branch: cws/96-session-chronicle
• Priority: Urgent
• Type: infra

Context

Claude Code sessions are ephemeral — learnings evaporate between sessions. The memory system is reactive rather than proactive. Mistakes repeat because feedback memories aren’t reliably enforced.

Scope

1. SessionStart hook (chronicle-init.sh) — creates chronicle file, injects context reminder
2. SessionEnd hook (chronicle-end.sh) — machine-generated summary safety net
3. /session-retro skill — deep retrospective with memory update proposals
4. AGENTS.md ## Session Chronicle section — contract for event logging
5. Hook configuration in .claude/settings.json

Acceptance Criteria

• SessionStart hook creates ~/.claude/projects/<project-dir>/chronicle/YYYY-MM-DD-<branch>.md with correct frontmatter on startup, resume, compact, and clear events
• SessionEnd hook appends machine summary when ## Summary section is empty
• /session-retro appears in Claude Code skill menu
• AGENTS.md documents the 8 event taxonomy tags
• make qa-local passes