context-keeper: Instructions file for Claude Code

CLAUDE.md

context-keeper CLAUDE.md is an instructions file for Claude Code from jarmstrong158/context-keeper. It costs 4,969 tokens per session, scanned A, original, MIT.

Instructions for Context Keeper, a project-memory service for Claude Code. It records architectural decisions, workflows, and constraints in a project’s .context/ folder so they can be reused across conversations.

In plain words
What is it for?
Use it to determine which project’s memory to use and to record, update, retire, or remove outdated project notes.
Why use it?
It reduces the risk of forgetting earlier decisions or breaking project rules when work continues in a new conversation.

Instructions file for Claude Code

Written for Claude Code: SessionStart hook event. Also seen: mentions subagents; mentions Claude Code.

This is jarmstrong158/context-keeper's own configuration. It tells Claude Code how to work on context-keeper itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything context-keeper configures →

Reuse

Borrowing it

Nothing to install: this file belongs to jarmstrong158/context-keeper. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/jarmstrong158/context-keeper/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/jarmstrong158/context-keeper

Made for: Claude Code.

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 context-keeper CLAUDE.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/jarmstrong158/context-keeper/claude-md/github.svg)](https://agentmods.dev/instructions/jarmstrong158/context-keeper/claude-md)
Your own site
<a href="https://agentmods.dev/instructions/jarmstrong158/context-keeper/claude-md"><img src="https://agentmods.dev/badge/instructions/jarmstrong158/context-keeper/claude-md/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 context-keeper CLAUDE.md

Your own site · 80×15
<a href="https://agentmods.dev/instructions/jarmstrong158/context-keeper/claude-md"><img src="https://agentmods.dev/badge/instructions/jarmstrong158/context-keeper/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 4,969 This file is loaded in full into every session.
When invoked 4,969 The same file — it is already loaded in full.
Security scan A 1 finding. 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 $0.04969 $0.04969
Opus 5.5 $0.01988 $0.01988
Sonnet 5.5 $0.00994 $0.00994
Haiku 4.5 $0.00497 $0.00497

Measured 2mo ago against content hash 74b6ac4109c8, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

context-keeper CLAUDE.md scanned grade A with 1 finding 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 2mo 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

**Surfaces 1 and 3 are on the critical path — treat their cost as a budget.** A PreToolUse hook runs before the tool does, so every millisecond it spends delays every Edit and Write in every project. `hooks/scope_guard.p
CLAUDE.md · 219 lines

How it starts

The opening of the file, as written. The whole thing — 219 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Context Keeper MCP Server

Context Keeper maintains project memory across Claude conversations: architectural decisions, pipeline flows, and constraints that must not be forgotten or violated.

Project Resolution

Context Keeper stores data in a .context/ directory inside a project. The server resolves the project directory in this order:

  1. CONTEXT_KEEPER_PROJECT env var (explicit opt-in — trusted)
  2. The Xylem session pointer ~/.xylem/active_project.json (override with XYLEM_ACTIVE_PROJECT_FILE), written by the Xylem SessionStart hook. Also an explicit opt-in: it exists so a persistent server follows the session's project rather than the directory it happened to be launched from, so it outranks cwd discovery.
  3. cwd, but only if it already contains a .context/ directory
  4. Walk parent dirs from cwd, returning the first ancestor that already contains a .context/ (git-style discovery — so launching from a subdirectory of your project still resolves correctly)
  5. Otherwise: refuse. record_*, update_entry, deprecate_entry, and prune_stale all return an "unresolved project" error.

Steps 3 and 4 only resolve to directories that already contain .context/. The server never creates one implicitly, so you will never silently create a stray .context/ in the wrong directory. The footgun from earlier versions — where Claude Code was launched from a parent directory and polluted it — is fixed at the code level.

All 14 tools accept project_dir for explicit cross-project targeting. When cwd doesn't resolve, pass project_dir to any tool — including record_*.

Still good practice:

  • When recording to a non-obvious project, confirm with the user which project you're targeting before calling record_*.

Capture Loop

Context Keeper has two halves:

  1. Retrieval (session start): The SessionStart hook injects the compaction report and project summary directly into context (it runs the handlers itself and prints their output). Retrieval is automatic and unskippable — you do not need to call the tools to be oriented on what's already recorded. get_compaction_report / get_project_summary remain callable on demand.

Read the full file on GitHub · 219 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. 2mo ago First seen · 219 lines · 4,969 tokens per session scan A 74b6ac4109c8

Subscribe to this mod's changes

context-keeper CLAUDE.md is an instructions file published in the GitHub repository jarmstrong158/context-keeper (1 stars, last pushed 2mo ago), licensed MIT. It adds 4,969 tokens to every session, about $0.0199 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Related

context-keeper CLAUDE.md compared with instructions from other repositories

context-keeper CLAUDE.md next to 6 instructions from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
context-keeper CLAUDE.mdjarmstrong158/context-keeperInstructions file12mo agoMITA4,969Claude Code
vscode buildNext.instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA9,719GitHub Copilot
next.js AGENTS.mdvercel/next.jsInstructions file143kyesterdayMITA7,461Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchainInstructions file149kyesterdayMITA4,680Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA5,516GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscodeInstructions file195kyesterdayMITA3,093GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harnessInstructions file274k2d agoMITA4,313Codex, OpenCode