| name | diary |
| description | Use when the user says 'save diary', 'log session', 'wrapping up', or at end of a productive session. |
| version | 1.1.0 |
📓 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
| Context | Status | Priority |
|---|
| User says "save diary", "log session", "write diary" | ACTIVE — write diary | P1 |
| User explicitly says they're done ("that's it", "wrapping up") | ACTIVE — suggest diary if work was done | P2 |
| Multi-agent session (Builder/Reviewer role) | DORMANT — Manager handles diary | — |
| Mid-session, user is actively coding | DORMANT — don't interrupt flow | — |
| Casual conversation, no code changes made | DORMANT — nothing to log | — |
| User asks to recall past sessions ("what did we do") | DORMANT — Echo handles recall, not Diary | — |
| User says "save project" or "handoff" | DORMANT — Project skill handles this | — |
| Session just started, no work yet | DORMANT — nothing to log | — |
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:
| Temptation | Why it matters |
|---|
| "Nothing important happened" | Even small decisions have context worth capturing. |
| "Commits capture everything" | Commits don't capture decisions, blockers, or next steps. |
| "Skip the handoff section" | Handoffs are the most valuable part for session continuity. |
Protocol
Never pass a JSON payload as a quoted command-line argument. Write it to a file and pipe it in with the dash sentinel, as every command below shows. On Windows, cmd.exe treats single quotes as ordinary characters, so a redirection operator anywhere in a quoted payload is executed rather than passed.
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.
-
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
-
Check git log for commits:
git log --oneline -10
-
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]
-
Save to SQLite database (primary storage):
Write the payload to a file, then pipe it in with - as the argument. A payload on stdin is never seen by the shell's parser, so a redirection operator inside your prose cannot be read as one.
cat session.json | python "$MEMSTACK_PATH/db/memstack-db.py" add-session -
session.json contains:
{"project":"<name>"
python -m memstack_skill_loader.diary_ingest "memory/sessions/{date}-{project}.md"
This parses the ## FACTS block and stores each fact with source_type='diary'.
Read the summary it prints. This step is not fire-and-forget. It reports N ingested, M duplicate, K skipped on stdout, followed by one indented reason per skipped line naming the line number and what was wrong with it. The exit code classifies the outcome:
| Exit | Meaning |
|---|
| 0 | Nothing was lost: facts ingested, an all-duplicates re-run, or no FACTS block at all (which prints nothing at all). |
| 1 | Total loss. The block held lines and not one of them ingested. |
| 2 | Store failure. The run aborted at the first bad row; the Memory Engine is broken, not the diary. |
If K is not 0, fix those lines in the markdown and run the command again. A skipped line is a fact this session was supposed to hand to the next one and did not, and the most common cause is a | inside a claim. Re-running is safe: facts dedupe on source + subject + claim, so anything already stored comes back as a duplicate rather than being written twice.
A non-zero exit never means the diary failed to save. The markdown and the SQLite row are already written by this point, and ingestion cannot undo them.
FACTS Block — Cross-Session Memory
The ## FACTS block is how a session hands durable, atomic knowledge to future sessions. It is machine-parsed, so the format is fixed. One fact per line:
subject | claim | method [| entities]
- subject — a dotted-path namespace, lowercase (e.g.
memstack.dashboard.start, adminstack.portal.auth). Group related facts under a shared prefix.
- claim — exactly one assertion. Keep it self-contained. Must not contain a
|.
- method — how you know it, one of:
verified (you saw it work / read the code / ran it), reported (stated but unconfirmed), inferred (deduced), assumed (a guess — scored lowest).
- entities — optional 4th field: comma-separated tags this fact touches.
Examples (note the granularity)
## FACTS
memstack.dashboard.start | start_dashboard() in dashboard.py, port 3333, proxy opt-in | verified
memstack.memory.recall-scoring | recall score = confidence * exp(-age/half_life), computed at query time, never stored | verified
adminstack.portal.auth | portal uses Supabase magic-link auth, not passwords | reported | supabase, auth
memstack.memory.corrections | a superseded fact cannot be corrected; corrections extend from the live tip | verified | correction
What to include
- Only facts worth remembering across sessions. Not "ran the tests" — that's in the diary body. A fact is something a future session would waste time rediscovering: a port, an entry point, an auth model, a non-obvious constraint.
- Prefer
verified over reported. If you actually confirmed it, say so — verified facts are trusted and decay slowest. Don't inflate: an unconfirmed claim is reported.
- Corrections of prior beliefs are the most valuable entries. If this session overturned something an earlier session believed ("the port is 3333, not 8080"; "auth is magic-link, not passwords"), record the corrected claim as a fact — that is exactly the knowledge that stops the team repeating a mistake.
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
| Data | Source |
|---|
| Uncommitted changes | git status --short |
| Recent commits | git log --oneline -5 |
| Recent shell commands | Shell history (last 5) |
| Recently modified files | Files modified since last git operation |
| Branch and project | Git branch + directory name |
How It Differs from Manual Diary
| Manual Diary | PreCompact Diary |
|---|
| Trigger | User says "save diary" | Automatic before compaction |
| Content | Full narrative with decisions, handoff | Snapshot of working state |
| Storage | SQLite + memory/sessions/ | .claude/diary/ only |
| Purpose | Session documentation | Context recovery after compaction |
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
| Event | Script | Matcher | Timeout | Purpose |
|---|
| PreToolUse | pre-tool-notify.sh | Write|Edit|MultiEdit|Bash | 10s | TTS voice alert before approval prompts |
| PreToolUse | pre-push.sh | Bash (git push) | 60s | Build verification + secrets scan before push |
| PostToolUse | post-commit.sh | Bash (git commit) | 10s | Debug artifact + secrets scan after commit |
| PostToolUse | post-tool-monitor.sh | Write|Edit|MultiEdit|Bash | 10s | Observation capture — logs tool calls to .claude/observations/ |
| SessionStart | session-start.sh | (all) | 10s | CLAUDE.md indexing, monitoring ping |
| SessionStart | session-context-load.sh | (all) | 15s | Context injection — last 3 diary + observation summaries → .claude/session-context.md |
| Stop | session-end.sh | (all) | 10s | Monitoring API session-complete ping |
| PreCompact | pre-compact.sh | (all) | 15s | Auto-save diary snapshot before context compaction |
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)
- Lv.8 — FACTS Ingestion: Added the
## FACTS block — atomic, machine-parsed cross-session knowledge (subject | claim | method | entities) ingested into the Memory Engine via diary_ingest after each save. Fail-open, dedupe-safe, corrections-first. (Origin: MemStack Memory Engine step 4, Jul 2026)
