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.
npx skills add OutlineDriven/outline-driven-development --skill cpp-modulesgit clone --depth 1 https://github.com/OutlineDriven/outline-driven-developmentWrote 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.
[](https://agentmods.dev/skills/outlinedriven/outline-driven-development/cpp-modules)<a href="https://agentmods.dev/skills/outlinedriven/outline-driven-development/cpp-modules"><img src="https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/cpp-modules/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.
<a href="https://agentmods.dev/skills/outlinedriven/outline-driven-development/cpp-modules"><img src="https://agentmods.dev/badge/skills/outlinedriven/outline-driven-development/cpp-modules.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00050 | $0.01418 |
| Opus 5 | $0.00025 | $0.00709 |
| Sonnet 5 | $0.00010 | $0.00284 |
| Haiku 4.5 | $0.00005 | $0.00142 |
Grade A, and why
cpp-modules 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 3d 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.
How it starts
The opening of the file, as written. The whole thing — 71 lines — stays where its author put it; the contents beside it link to each section on GitHub.
C++20 modules
Contract
| Field | Bound contract |
|---|---|
| Trigger | The user writes or builds export module code, asks how named modules differ from header units, needs the CMake wiring for module interface units, or gets a module-not-found, redefinition, or stale-BMI error. |
| Authority | Read-only. The skill emits module source shapes, compiler invocations, and CMake snippets to chat; the user applies them. Rollback is not needed. No remote mutation. |
| Side effect | Chat output. Any scratch build to confirm a flag runs on scratch files. |
| Done | The module layout, the per-compiler build commands, and the CMake wiring are reported for the user's compiler and CMake version, and every error in the request maps to a cause and fix. |
Inputs
- Compiler and version: required. Clang 23.1.0 and GCC 16.2 are current stable; both accept the commands below.
- CMake version when CMake is in use: required. Current stable is 4.4.3; the stable
CXX_MODULESfile set needs 3.28 or later. - Generator: required with CMake. Ninja 1.11 or later, Ninja Multi-Config, or Visual Studio; Makefile generators do not support modules.
- Module layout the user has or wants: required. Primary interface, partitions, implementation units, and any legacy headers with macros.
Procedure
- Classify each translation unit. Primary interface unit:
export module m;in a.cppm(or.ixx) file. Partition interface:export module m:part;, re-exported from the primary withexport import :part;. Implementation unit:module m;with no exports. Header unit:import <vector>;orimport "local.h";, a bridge for legacy headers. Prefer named modules; use header units only to bridge. Done when: every file has one classification. - Handle macros. Macros do not cross
import. Code that needs a header's macros puts#includein the global module fragment: a file that opens withmodule;, then the includes, thenexport module m;. Wrap a C library the same way and re-export withexport using ::name;. Done when: every macro dependency is in a global module fragment. - Build with Clang. Precompile the interface:
clang++ -std=c++20 --precompile math.cppm -o math.pcm. Compile users against it:clang++ -std=c++20 -fmodule-file=math=math.pcm -c main.cpp -o main.o. Link the interface's object as well:clang++ -std=c++20 -fmodule-file=math=math.pcm math.pcm main.o -o prog. Done when: the three commands are given in dependency order. - Build with GCC.
g++ -std=c++20 -fmodules-ts -c math.cppm -o math.owritesmath.gcmundergcm.cache/in the working directory, andg++ -std=c++20 -fmodules-ts main.cpp math.o -o progfinds it there. GCC 16 also accepts-fmodules; both spellings compile on the installed 16 line. Done when: the interface is compiled before its importers and the cache directory is named. - Wire CMake 3.28 or later:
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 3d ago First seen · 71 lines · 50 tokens per session scan A 825c1139b492
cpp-modules is a skill published in the GitHub repository OutlineDriven/outline-driven-development (52 stars, last pushed 4d ago), licensed Apache-2.0. It adds 50 tokens to every session and 1,418 once invoked, about $0.0003 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 2026-09-06.
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