session-archaeology

session-archaeology is a skill for Claude Code from itallstartedwithaidea/agent-skills. It costs 37 tokens per session (2,253 once invoked), scanned A, original, MIT.

A method for studying old AI-agent sessions—the recorded actions, errors, corrections, and results—to find patterns that can be reused.

In plain words
What is it for?
Use it to review individual or many past sessions, identify reliable prompt and tool-use patterns, and turn findings into new or improved skills.
Why use it?
It helps teams learn from repeated failures instead of treating every agent session as an isolated event.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions Claude Code; mentions Codex; mentions Gemini CLI.

Part of the claude-mythos-skills plugin — 10 skills shipped together , and of all-skills

Good fit Use it to review individual or many past sessions, identify reliable prompt and tool-use patterns, and turn findings into new or improved skills.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/itallstartedwithaidea/agent-skills/session-archaeology
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 itallstartedwithaidea/agent-skills --skill session-archaeology
Clone the repo
git clone --depth 1 https://github.com/itallstartedwithaidea/agent-skills

Made for: Claude Code.

Or install claude-mythos-skills, the plugin that ships this one along with the rest of its 10 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-archaeology

README.md
[![agentmods](https://agentmods.dev/badge/skills/itallstartedwithaidea/agent-skills/session-archaeology/github.svg)](https://agentmods.dev/skills/itallstartedwithaidea/agent-skills/session-archaeology)
Your own site
<a href="https://agentmods.dev/skills/itallstartedwithaidea/agent-skills/session-archaeology"><img src="https://agentmods.dev/badge/skills/itallstartedwithaidea/agent-skills/session-archaeology/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for session-archaeology

Your own site · 80×15
<a href="https://agentmods.dev/skills/itallstartedwithaidea/agent-skills/session-archaeology"><img src="https://agentmods.dev/badge/skills/itallstartedwithaidea/agent-skills/session-archaeology.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,253 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 $0.00037 $0.02253
Opus 5 $0.00018 $0.01126
Sonnet 5 $0.00007 $0.00451
Haiku 4.5 $0.00004 $0.00225

Measured 9d ago against content hash 4c0153026653, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

session-archaeology 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 9d 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.

skills/claude-mythos/session-archaeology/SKILL.md · 212 lines

How it starts

The opening of the file, as written. The whole thing — 212 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Session Archaeology

Part of Agent Skills™ by googleadsagent.ai™

Description

Session Archaeology is the systematic excavation and analysis of past agent sessions to extract reusable patterns, identify recurring failure modes, and derive new skills from operational history. Every agent session produces a rich artifact — a complete transcript of reasoning, tool usage, errors, corrections, and final outcomes. Most teams discard this data. Session Archaeology treats it as the most valuable training signal available: real-world execution traces from your specific domain, your specific codebase, and your specific workflows.

This skill formalizes the methodology used at googleadsagent.ai™ to continuously improve Buddy™ by mining thousands of past Google Ads analysis sessions. The archaeology process identifies which prompt patterns led to accurate recommendations, which tool call sequences completed reliably, and which error recovery strategies succeeded. These findings are then codified into new Agent Skills™ or refinements to existing ones, creating a flywheel of continuous improvement.

The process operates at three levels: individual session review (what went wrong in this specific run), cross-session pattern analysis (what patterns recur across many runs), and trend identification (how is agent behavior evolving over time). Each level yields different insights and different types of improvements.

Use When

  • Agent quality has plateaued and you need new optimization signals
  • You want to derive new skills or rules from real execution data
  • Recurring failures suggest systematic issues rather than random errors
  • Onboarding new team members who need to understand agent behavior patterns
  • Building regression test suites from real session transcripts
  • Preparing for model version migrations (comparing behavior across model versions)

How It Works

Read the full file on GitHub · 212 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. 9d ago First seen · 212 lines · 37 tokens per session scan A 4c0153026653

Subscribe to this mod's changes

session-archaeology is a skill published in the GitHub repository itallstartedwithaidea/agent-skills (37 stars, last pushed 4mo ago), licensed MIT. It adds 37 tokens to every session and 2,253 once invoked, about $0.0002 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 2026-08-30.