boffin-cpp-routing

A rule that activates C++ architecture guidance for C++ source files. It distinguishes C++ headers and source from plain C files before applying that guidance.

In plain words
What is it for?
Use it in projects containing both C and C++ to route files to the correct architecture rules and references.
Why use it?
It keeps the coding agent from applying C++-specific rules to files that contain only C code and directs C++ files to the appropriate architecture pack.

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/micsm/boffin/boffin-cpp-routing
Clone the repo
git clone --depth 1 https://github.com/MicSm/boffin

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 184 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00000 $0.00184
Opus 5 $0.00000 $0.00092
Sonnet 5 $0.00000 $0.00037
Haiku 4.5 $0.00000 $0.00018

Measured 2d ago against content hash f214b281e132, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

boffin-cpp-routing 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.

.cursor/rules/boffin-cpp-routing.mdc · 19 lines

What it actually says

C++ Pack Activation

For C++ source files:

  • Load packs/cpp-architecture/pack.urf.md.
  • Use its ## ROUTING and ## LEAVES records for leaf selection.
  • Use its ## STAGE-REFS records to gather the family K ids (and their mirrored X ids) at each stage of the walk.

For ambiguous .h or .c files that reach this rule via the always-on router:

  • Apply cpp-architecture only if the file contains C++ constructs (class, template, namespace, references, std::, noexcept, overloads).
  • If the file is plain C, stay on universal only.
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 · 19 lines · 184 tokens per session scan A f214b281e132

Subscribe to this mod's changes

boffin-cpp-routing is a cursor rule published in the GitHub repository MicSm/boffin (38 stars, last pushed 10d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 184 tokens. 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.