synapse

synapse is a cursor rule for coding agents from myelixlabs/synapse-mcp. It costs 323 tokens per session, scanned A, original, MIT.

Rules for using Synapse MCP, a persistent structured map of a codebase. They define how agents should inspect code, make changes, debug errors, review diffs, and save knowledge.

In plain words
What is it for?
Use it to query code structure, apply simulated edits with rollback, map stack traces, review change impact, and retain codebase notes across sessions.
Why use it?
They provide a safer and more consistent way to understand code relationships and reduce the risk of edits that break callers or contracts.

Cursor rule

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/myelixlabs/synapse-mcp/synapse
Clone the repo
git clone --depth 1 https://github.com/myelixlabs/synapse-mcp

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 synapse

README.md
[![agentmods](https://agentmods.dev/badge/rules/myelixlabs/synapse-mcp/synapse.svg)](https://agentmods.dev/rules/myelixlabs/synapse-mcp/synapse)
Your own site
<a href="https://agentmods.dev/rules/myelixlabs/synapse-mcp/synapse"><img src="https://agentmods.dev/badge/rules/myelixlabs/synapse-mcp/synapse.svg" alt="Measured on agentmods" height="20"></a>
Per session 323 This file is loaded in full into every session.
When invoked 323 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 $0.00323 $0.00323
Opus 5 $0.00161 $0.00161
Sonnet 5 $0.00065 $0.00065
Haiku 4.5 $0.00032 $0.00032

Measured 2d ago against content hash a773c08fb06e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

synapse 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 2d 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.

rules/synapse.mdc · 29 lines

What it actually says

Synapse MCP — Graph-First Workflow

You have access to Synapse MCP, a persistent AST code-knowledge graph of this codebase. Follow these rules to make the most of it.

Discovery

  • Use ask_synapse for ALL codebase questions first — before grepping, before reading files.
  • For "can I delete X?" or "is X still used?", include inputs.chunk_id or inputs.symbol with arity.
  • If ask_synapse returns completion_state: "tool_call_required", follow the first safe next_tool_calls entry.

Writing Code

  • Use write_safely for ALL file modifications. It simulates the edit in memory, verifies callers, and auto-rolls back on failure.
  • Never use standard file write tools for code edits. write_safely exists specifically to prevent broken files.

Debugging

  • When pasting a stack trace, use resolve_stack to map frames to AST chunks and get root-cause analysis.
  • Use review_diff before committing — it ranks blast radius, broken contracts, and tests to run.

Memory

  • Synapse persists summaries across sessions. When you learn something about the codebase, write it to the knowledge cache so future sessions benefit.

Fallback

  • Only fall back to shell grep/file reads if Synapse returns no safe route or the task is explicitly non-codebase.
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. 2d ago First seen · 29 lines · 323 tokens per session scan A a773c08fb06e

Subscribe to this mod's changes

synapse is a cursor rule published in the GitHub repository myelixlabs/synapse-mcp (1 stars, last pushed 2d ago), licensed MIT. It adds 323 tokens to every session, about $0.0016 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.