session-start

session-start is a skill for Claude Code from Aiyo28/memento-os. It costs 56 tokens per session (1,001 once invoked), scanned A, original, MIT.

A session-opening routine that gathers the project's saved context, recent decisions, pending work, and possibly outdated notes.

In plain words
What is it for?
Use it when starting work, asking what has happened, or needing a briefing before continuing a project.
Why use it?
It reduces the time spent reconstructing where work stopped and helps reveal context that may no longer be current.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions AGENTS.md.

Part of the memento-os plugin — 7 skills shipped together

Good fit Use it when starting work, asking what has happened, or needing a…

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/aiyo28/memento-os/session-start
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add Aiyo28/memento-os --skill session-start
Clone the repo
git clone --depth 1 https://github.com/Aiyo28/memento-os

Made for: Claude Code.

Or install memento-os, the plugin that ships this one along with the rest of its 7 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for session-start

README.md
[![agentmods](https://agentmods.dev/badge/skills/aiyo28/memento-os/session-start.svg)](https://agentmods.dev/skills/aiyo28/memento-os/session-start)
Your own site
<a href="https://agentmods.dev/skills/aiyo28/memento-os/session-start"><img src="https://agentmods.dev/badge/skills/aiyo28/memento-os/session-start.svg" alt="Measured on agentmods" height="20"></a>
Per session 56 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,001 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00056 $0.01001
Opus 5 $0.00028 $0.00500
Sonnet 5 $0.00011 $0.00200
Haiku 4.5 $0.00006 $0.00100

Measured 6d ago against content hash c13fbb3fb839, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

session-start scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

adapters/codex/skills/session-start/SKILL.md · 97 lines

How it starts

The opening of the file, as written. The whole thing — 97 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/session-start

Load context. Display briefing. Flag staleness. Get to work.

Steps

1. Load L0 — Session Continuity

Read NEXT.md in the project root.

2. Load L1 — Project Context (~600 tokens)

Read (skip if missing):

  • Project AGENTS.md
  • Vault _context.mdtop 3 sections only: Summary + Key Numbers + Active Reasoning Artifacts table. STOP before Doc Index / Decision Log / Open Questions / Related sections. This is the L1 partial read rule.
  • Peer Card (People/Self.md in vault or memory folder) — structured user profile with communication style, decision patterns, strengths, growth areas. Load the Communication Style and Decision Patterns tables only (~20 lines). Template provided in starter vault. Skip if missing — suggest creating one on first session.

3. Seed Activation Check

Scan [S] entries in the Active Reasoning Artifacts table:

  • If activation condition appears met → surface in briefing under "Seeds Ready"
  • If dormant > 90 days → flag for review
  • When a seed activates, suggest: "This seed is ready. Want to /decide on it?"

4. Staleness Check

Scan [D], [I], [E] entries in the Active Reasoning Artifacts table:

First: check for expired artifacts (those with expires: YYYY-MM-DD past today's date). Flag as EXPIRED in briefing regardless of priority.

Then: priority-based staleness (for artifacts without expiry):

Priority Age Status
critical > 90 days STALE — review invalidation trigger (may still be valid)
volatile > 30 days NEEDS RESOLUTION — decide, upgrade to critical, or delete
settled > 90 days STALE — likely safe to archive
noise Any Should not be in table — flag for removal

5. Display Briefing

## Session Briefing — {Project Name}
**Date:** {today}
**Memory:** {score}/10 | {total} artifacts | {seeds} seeds | streak: {n}

### Continue
{from NEXT.md}

### Active Decisions
{from _context.md — show critical and volatile only, up to 7}

### Seeds Ready (if any)
{[S] artifacts where activation condition appears met}

### Stale Artifacts (if any)
{list with age and invalidation trigger}

### Pending
{from NEXT.md "Decide" section}

Read the full file on GitHub · 97 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 97 lines · 56 tokens per session scan A c13fbb3fb839

Subscribe to this mod's changes

session-start is a skill published in the GitHub repository Aiyo28/memento-os (3 stars, last pushed yesterday), licensed MIT. It adds 56 tokens to every session and 1,001 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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