diary

📓 Diary — Logging Session...

Document what was accomplished in each CC session for future recall.

Activation

When this skill activates, output:

📓 Diary — Logging session...

Then execute the protocol below.

Context Guard

When NOT to Fire

• Do NOT fire autonomously. Only activate when the user explicitly requests it ("save diary", "log session", "wrapping up").
• Multi-agent sessions: If you are operating as Builder, Reviewer, or any non-Manager agent in a multi-agent session, do NOT fire diary. Only the Manager or a standalone session should trigger diary.
• No work done: If no meaningful changes were made (no commits, no file edits), skip diary.

Reminders

When the user asks to save a diary, keep these in mind:

Protocol

Always use Bash for all memstack-db.py commands. Do not use PowerShell or CMD -- PowerShell mangles JSON arguments.

All JSON field values must be plain strings. Never pass arrays or objects. If multiple items (files, commits, decisions), join them as a comma-separated string.

1. Summarize the session:

   • Project name and working directory
   • Date and approximate duration
   • What was built or changed
   • Key files created or modified
   • Commits made (hashes and messages)
   • Decisions made and why
   • Problems encountered and solutions

2. Check git log for commits:

   git log --oneline -10
   

3. Format the diary entry:

   # Session Diary — {project} — {date}
   
   ## Accomplished
   - Item 1...
   
   ## Files Changed
   - path/to/file.ts — description
   
   ## Commits
   - abc1234 Message
   
   ## Decisions
   - Decision: reason
   
   ## Next Steps
   - What to do next
   
   ## Session Handoff
   **In Progress:** [what was actively being worked on when session ended]
   **Uncommitted Changes:** [list any unstaged/uncommitted work, or "None"]
   **Pick Up Here:** [exact instruction for next session — specific enough to start cold]
   **Session Context:** [anything important that isn't captured elsewhere — temp decisions, debugging state, gotchas discovered]
   

4. Save to SQLite database (primary storage):

   python "$MEMSTACK_PATH/db/memstack-db.py" add-session '{"project":"<name>","date":"<YYYY-MM-DD>","accomplished":"<bullets>","files_changed":"<bullets>","commits":"<bullets>","decisions":"<bullets>","problems":"<bullets>","next_steps":"<bullets>","duration":"<estimate>","raw_markdown":"<full text>"}'
   

5. Save insights for cross-project search:

   python "$MEMSTACK_PATH/db/memstack-db.py" add-insight '{"project":"<name>","type":"<type>","content":"<insight>","context":"Session <date>","tags":"<project>"}'
   

   Choose <type> deliberately from this vocabulary — do not default to one:

   • gotcha — something that bit us and the fix. Non-obvious behavior a future session would trip on again.
   • lesson — a general rule learned the hard way. Broader than one bug.
   • pattern — a reusable approach or convention that worked.
   • warning — a known hazard to avoid. Not yet a bug, but will be.
   • failed_approach — something tried that did not work, and why. Prevents retrying it.
   • architecture — a structural fact about how a system is built.
   • decision — a choice made and the reasoning. Historical record.

   The first five are procedural — an agent can act on them at retrieval time. architecture and decision are record. When a row could be either, prefer the procedural type.

   Unknown types pass through unchanged but come back as type_unknown in the JSON response — that is the signal to pick a type from the list above.

   CRITICAL: The field name is "content", NOT "insight". Using "insight" will fail with a missing required field error.

6. Update project context with last session date:

   python "$MEMSTACK_PATH/db/memstack-db.py" set-context '{"project":"<name>","last_session_date":"<YYYY-MM-DD>"}'
   

7. Also save markdown copy to memory/sessions/{date}-{project}.md (export format, human-readable backup)

Session File Size Management

The 500-line limit on markdown files is no longer a concern since SQLite is the source of truth. Markdown files in memory/sessions/ are now just human-readable exports. Old markdown files are preserved but not the primary storage.

Inputs

• Current session context
• Project name from working directory or config.json
• Git log for commit history

Outputs

• Session entry in SQLite database
• Insights extracted from decisions
• Markdown backup in memory/sessions/
• Brief confirmation summary

Example Usage

User: "save diary"

📓 Diary — Logging session...

Saved: memory/sessions/2026-02-18-adminstack.md

Project: AdminStack | Duration: ~2 hours
Accomplished: Built CC Monitor page, API routes, setup guide
Commits: 4 (45b4c42, d1c7e11, f6c8e18, f0e793f)
Files changed: 8

This session is now searchable via Echo.

PreCompact Hook — Automatic Compaction Diary

The diary system includes an automatic PreCompact hook that fires before Claude Code compresses the context window. This closes the gap where session context could be lost during long conversations.

Behavior

• Trigger: Fires automatically before every CC context compaction — no user action required
• Output: .claude/diary/{date}-compaction.md — one file per day, appends on multiple compactions
• Flag: Every entry includes COMPACTION_INTERRUPTED so the next session knows context was cut
• Timeout: 15 seconds — fast enough to never block compaction

What It Captures

How It Differs from Manual Diary

Session Resume

When resuming after compaction, check .claude/diary/ for entries with today's date. The COMPACTION_INTERRUPTED flag signals that the previous context was truncated and these files contain the lost state.

Configuration

Hook is registered in .claude/settings.json under PreCompact. Script lives at .claude/hooks/pre-compact.sh. Always exits 0 — must never block compaction.

Full Hook System (v3.3.2)

The Diary skill is part of a broader hook system that automates session lifecycle, security, and observability. All hooks follow the same defensive pattern: set -uo pipefail, SCRIPT_DIR resolution, all external commands wrapped with fallbacks, guaranteed exit 0.

Hook Registry — 7 hooks across 5 events

Architecture Notes

• Each hook is registered as an independent entry (Option B) in settings.json, giving it its own timeout budget
• PreToolUse hooks can block tool execution (exit 2 = block). All other hooks are non-blocking
• PostToolUse observation monitor writes to .claude/observations/YYYY-MM-DD.md — daily files, append-only
• SessionStart context loader is idempotent — overwrites .claude/session-context.md on each new session
• Both .claude/observations/ and .claude/session-context.md are in .gitignore (ephemeral runtime output)
• All scripts live in .claude/hooks/ and use ${CLAUDE_PROJECT_DIR} for portable path resolution

Level History

• Lv.1 — Base: Session logging with git integration. (Origin: MemStack v1.0, Feb 2026)
• Lv.2 — Enhanced: Added YAML frontmatter, context guard, 500-line limit with archive, activation message. (Origin: MemStack v2.0 MemoryCore merge, Feb 2026)
• Lv.3 — Advanced: SQLite as primary storage, auto-extract insights from decisions, markdown as backup export. (Origin: MemStack v2.1 Accomplish-inspired upgrade, Feb 2026)
• Lv.4 — Native: CC rules integration (.claude/rules/diary.md), always-on session logging awareness without skill file read. (Origin: MemStack v3.0-beta, Feb 2026)
• Lv.5 — Handoff: Added structured Session Handoff section — in-progress work, uncommitted changes, exact pickup instructions, session context preservation. (Origin: MemStack v3.1, Feb 2026)
• Lv.6 — PreCompact: Added automatic PreCompact hook — saves working state snapshot before CC context compaction, captures uncommitted changes, recent commands, and modified files with COMPACTION_INTERRUPTED flag. (Origin: MemStack v3.3.1, Mar 2026)
• Lv.7 — Hook System: Documented full 7-hook system across 5 CC lifecycle events — PreToolUse (TTS + pre-push), PostToolUse (post-commit + observation monitor), SessionStart (Headroom + context injection), Stop, PreCompact. (Origin: MemStack v3.3.2, Mar 2026)