Session Memory Skill

A skill for managing learnings and memory across sessions. Records and references past work, decisions, and learned patterns.

Trigger Phrases

This skill is automatically invoked by the following phrases:

• "What did we do last time?", "Continue from last time"
• "Show me the history", "Past work"
• "Tell me about this project"
• "what did we do last time?", "continue from before"

Overview

This skill saves work history to .claude/memory/ and enables knowledge continuity across sessions.

It also clarifies "where important information should be stored" (details: docs/MEMORY_POLICY.md).

Memory Structure

.claude/
├── memory/
│   ├── session-log.md      # Per-session log
│   ├── decisions.md        # Important decisions
│   ├── patterns.md         # Learned patterns
│   └── context.json        # Project context
└── state/
    └── agent-trace.jsonl   # Agent Trace (tool execution history)

Recommended Operation (SSOT/Local separation)

• SSOT (recommended for sharing): decisions.md / patterns.md
  • Consolidates "decisions (Why)" and "reusable solutions (How)"
  • Each entry has a title + tags (e.g., #decision #db) with an Index at the top
• Recommended as local: session-log.md / context.json / .claude/state/
  • Prone to noise/bloat; generally not Git-managed (decide individually if needed)

Auto-Recorded Information

session-log.md

Each session record is assigned a session ID obtained from the runtime environment. In Claude Code, ${CLAUDE_SESSION_ID} is preferred; in Codex, the Codex runtime session / thread ID is preferred. If neither is available, read .session_id from .claude/state/session.json, with datetime-based ID as final fallback. This improves cross-session traceability.

## Session: 2024-01-15 14:30 (session: abc123def)

### Tasks Completed
- [x] User authentication implementation
- [x] Login page creation

### Files Generated
- src/lib/auth.ts
- src/app/login/page.tsx

### Important Decisions
- Authentication method: Adopted Supabase Auth

### Handoff to Next Session
- Logout feature not yet implemented
- Password reset also needed

Note: ${CLAUDE_SESSION_ID} is an environment variable automatically set by Claude Code. This variable may not exist on the Codex side, so do not assume it is fixed; use the Codex runtime session / thread ID or .claude/state/session.json instead.

decisions.md

## Technology Selections

| Date | Decision | Reason |
|------|---------|--------|
| 2024-01-15 | Supabase Auth | Free tier available, easy setup |
| 2024-01-14 | Next.js App Router | Latest best practices |

## Architecture

- Components: `src/components/`
- Utilities: `src/lib/`
- Type definitions: `src/types/`

patterns.md

## Patterns in This Project

### Component Naming
- PascalCase
- Examples: `UserProfile.tsx`, `LoginForm.tsx`

### API Endpoints
- `/api/v1/` prefix
- RESTful design

### Error Handling
- Wrap in try-catch
- Error messages in English

context.json

{
  "project_name": "my-blog",
  "created_at": "2024-01-14",
  "stack": {
    "frontend": "next.js",
    "backend": "next-api",
    "database": "supabase",
    "styling": "tailwind"
  },
  "current_phase": "Phase 2: Core Features",
  "last_session": "2024-01-15T14:30:00Z"
}

Processing Flow

At Session Start

1. Load .claude/memory/context.json
2. Check previous session log
3. Retrieve recent edit history from Agent Trace
4. Identify incomplete tasks
5. Generate context summary

Agent Trace Usage:

# Get list of edited files from last session
tail -50 .claude/state/agent-trace.jsonl | jq -r '.files[].path' | sort -u

# Get project information
tail -1 .claude/state/agent-trace.jsonl | jq '.metadata'

During Session

1. Record important decisions to decisions.md
2. Add new patterns to patterns.md
3. Record file generation to session-log.md

At Session End

1. Generate session summary
2. Update context.json
3. Record handoff items for next session

Memory Optimization (CC 2.1.49+)

From Claude Code 2.1.49 onward, memory usage when resuming sessions has been reduced by 68%.

Recommended Workflow

# Use --resume for long work sessions
claude --resume

# Split large tasks and resume sessions
claude --resume "Continue from where we left off"

Memory efficiency has greatly improved — actively leverage session resumption.

/recap — Mid-Session Status Check (CC 2.1.108+)

The /recap command added in CC 2.1.108 (alias for /rewind) is used to quickly review what has been done so far in the current session. Most effective when combined with checking before returning to another session with --resume, or for mid-session checks during long work.

Recommended Timing:

# Typical usage flow
# 1. Check current work status
/recap

# 2. After manually appending to session-log.md if needed, resume session
claude --resume

/recap only reviews within the current session. Previous session content is checked via session-log.md or context inheritance with claude --resume.

Usage Examples

Continue from Last Time

User: "Continue from last time"

Claude Code:
📋 Previous Session (2024-01-15)

Completed tasks:
- User authentication
- Login page

Incomplete:
- Logout feature
- Password reset

Say "Create the logout feature" to continue implementation.

Check Project Status

User: "Tell me about this project"

Claude Code:
📁 Project: my-blog

Technology stack:
- Next.js + Tailwind CSS + Supabase

Current phase: Core feature development
Progress: 40% complete

Recent decisions:
- Adopted Supabase Auth
- Using App Router

Relationship with Claude Code Auto-Memory (D22)

Claude Code 2.1.32+ has an "auto-memory" feature that automatically saves cross-session learnings to ~/.claude/projects/<project>/memory/MEMORY.md.

It coexists with the Harness memory system as a 3-layer architecture:

Usage guidelines:

• If Layer 1 insights are important for the whole project → Promote to Layer 2 with /memory ssot
• Leave everyday learnings to Layer 1 (do not disable)
• Note parallel write contention when using Agent Teams

Details: D22: 3-Layer Memory Architecture

Notes

• Auto-save: Recommend appending a session summary to session-log.md automatically via hooks/Stop at session end (manual operation is fine if not set up)
• Privacy: Do not record sensitive information
• Git policy: decisions.md/patterns.md recommended for sharing; session-log.md/context.json/.claude/state/ recommended as local-only (details: docs/MEMORY_POLICY.md)
• Capacity management: When logs grow large, recommend "organize session log"