threadctx

A rule for using shared team memory during coding tasks. It checks earlier decisions and records useful discoveries when the memory tools are available.

In plain words
What is it for?
Use it before substantial work to search team notes, and after non-obvious fixes or decisions to save context.
Why use it?
It helps avoid repeating known fixes or architectural decisions and makes lessons available to teammates.

Cursor rule for Cursor

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.

agentmods
npx agentmods add rules/threadctx-dev/threadctx-mcp/threadctx
Clone the repo
git clone --depth 1 https://github.com/threadctx-dev/threadctx-mcp

Made for: Cursor.

Per session 217 This file is loaded in full into every session.
When invoked 217 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
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 $0.00217 $0.00217
Opus 5 $0.00109 $0.00109
Sonnet 5 $0.00043 $0.00043
Haiku 4.5 $0.00022 $0.00022

Measured yesterday against content hash 1d8bc7f085b8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

threadctx 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 yesterday.

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.

.cursor/rules/threadctx.mdc · 20 lines

What it actually says

Team memory (threadctx)

  • Before starting any non-trivial task, call memory_query with a short description of what you are about to do. Check for prior decisions, fixes, and gotchas on this repo before writing code — not after.
  • After resolving a non-obvious bug, making an architectural decision, or learning something that would save a teammate time, call memory_write to save it. Write it so a future reader has full context.
  • If the memory_query / memory_write tools are not available in this session: this repo uses threadctx for shared team memory, but it is not connected on this machine yet. Suggest the user run npx threadctx-mcp join (one command, ~30 seconds), then restart the session.
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. yesterday First seen · 20 lines · 217 tokens per session scan A 1d8bc7f085b8

Subscribe to this mod's changes

threadctx is a cursor rule published in the GitHub repository threadctx-dev/threadctx-mcp (1 stars, last pushed 1mo ago), licensed MIT. It adds 217 tokens to every session, about $0.0011 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.