memory-safety-patterns

Overview of memory-safety-patterns skill

What memory-safety-patterns is for

The memory-safety-patterns skill helps an agent reason about memory-safe design across C, C++, and Rust, with emphasis on ownership, RAII, smart pointers, lifetimes, and resource cleanup. It is most useful when you are building or reviewing backend and systems code where memory bugs are expensive, subtle, or security-relevant.

Best fit users and teams

This memory-safety-patterns skill is best for:

• backend engineers touching native modules, services, or performance-critical components
• teams migrating unsafe C or legacy C++ code toward safer patterns
• reviewers who need concrete guidance on leaks, dangling pointers, double frees, and resource ownership
• engineers comparing whether a problem should stay in C/C++ or move to Rust

The real job-to-be-done

Most users do not need a theory lesson on memory safety. They need help answering practical questions like:

• who owns this allocation or handle?
• when is cleanup guaranteed?
• which pointer type fits this lifetime model?
• how do I refactor manual cleanup into RAII?
• is this code safer in Rust, or can C++ patterns be enough?

That is where memory-safety-patterns adds value over a generic coding prompt.

What differentiates this skill

The repository is lightweight, but the content is focused. Instead of broad systems-programming advice, it concentrates on a small set of high-value safety patterns:

• memory bug categories and how patterns prevent them
• a safety spectrum from manual memory management to stronger ownership models
• cross-language framing, so recommendations can be adapted to existing stacks
• practical decision support for resource management, not just heap allocation

When this skill is a strong choice

Use memory-safety-patterns for Backend Development when your task involves:

• sockets, files, buffers, and manual cleanup paths
• FFI boundaries
• legacy code with unclear ownership
• concurrent code where data races may be coupled with lifetime issues
• refactoring repetitive init/cleanup code into safer wrappers

When it is not the right tool

Skip this skill if your project is mostly managed-runtime application code and memory safety is not a design concern. It is also not a replacement for sanitizer tooling, compiler warnings, or language-specific secure coding standards. It gives patterns and tradeoffs; it does not verify your binary or prove correctness.

How to Use memory-safety-patterns skill

Install context for memory-safety-patterns

The upstream skill does not publish its own install command in SKILL.md, so directory users typically add it from the source repository context, for example:

npx skills add https://github.com/wshobson/agents --skill memory-safety-patterns

If your agent platform uses a different skill loader, add the skill from:

https://github.com/wshobson/agents/tree/main/plugins/systems-programming/skills/memory-safety-patterns

Read this file first

Start with:

• SKILL.md

This skill has no extra resources/, rules/, or helper scripts, so nearly all useful guidance is in that one file. That is good for quick adoption, but it also means your prompt quality matters more because there is less built-in workflow scaffolding.

What input the skill needs to work well

For strong memory-safety-patterns usage, give the agent concrete context:

• language: C, C++, or Rust
• resource type: heap memory, file descriptors, sockets, locks, mapped memory
• current ownership model: raw pointers, unique_ptr, shared_ptr, references, borrowed handles
• failure mode: leak, use-after-free, unclear cleanup, race-prone shared state
• target output: review, refactor plan, code sketch, migration advice, or bug analysis

Weak input:

• “Make this memory safe.”

Strong input:

• “Review this C++ connection pool code for ownership and cleanup risks. Replace manual new/delete and early-return cleanup with RAII, explain whether unique_ptr or stack ownership is better, and call out any remaining race or lifetime risks.”

Turn a rough goal into a good prompt

A good prompt for memory-safety-patterns install and first use usually has four parts:

1. Code or architecture slice
   Paste the function, class, or subsystem that allocates or owns resources.

2. Risk you care about most
   Example: “Prevent use-after-free during reconnect.”

3. Constraints
   Example: “Cannot rewrite module in Rust; must stay compatible with C ABI.”

4. Desired output shape
   Example: “Give me a ranked list of issues, then a minimal refactor.”

Template:

Use the memory-safety-patterns skill to review this [language] code. Focus on [resource/lifetime problem]. Explain the current ownership model, identify the top memory-safety risks, and propose a safer design using [RAII / smart pointers / Rust ownership]. Keep changes compatible with [constraints].

Practical prompt examples

Use it for C cleanup refactoring

Use memory-safety-patterns to refactor this C module that allocates buffers and opens file descriptors across multiple error paths. Identify leak and double-free risks, then propose a wrapper or ownership convention that makes cleanup deterministic.

Use it for C++ pointer selection

Use the memory-safety-patterns skill on this C++ service code. Decide where raw pointers should become unique_ptr, shared_ptr, references, or values. Explain lifetime assumptions and where shared ownership would hide bugs instead of fixing them.

Use it for Rust API design

Use memory-safety-patterns to review this Rust API around borrowed and owned data. Check whether lifetimes are expressing the real ownership model, and suggest where Arc, Box, or borrowing would simplify safety without overcomplicating the interface.

Suggested workflow in real projects

A practical workflow for memory-safety-patterns usage is:

1. ask for an ownership map of the current code
2. ask for the top 3 memory bug risks
3. ask for the minimal safe redesign
4. ask for code-level changes
5. ask for edge cases: early returns, panics/exceptions, concurrency, and FFI boundaries

This staged approach works better than asking for “fully memory-safe code” in one jump.

What the skill is especially good at

The skill is strongest when you need:

• a plain-language explanation of ownership
• comparison of C, C++, and Rust safety models
• pattern selection such as RAII vs manual cleanup
• guidance on avoiding common bug classes like leaks and dangling pointers

It is particularly helpful in reviews, migrations, and design discussions before code is rewritten.

Limits you should know before adopting

Because the repository is a single SKILL.md without support files, memory-safety-patterns guide quality depends on your examples and constraints. Do not expect:

• repo-specific static analysis integration
• automated enforcement rules
• deep language-corner-case coverage for every standard library type
• exploit analysis or sanitizer output interpretation unless you provide the evidence

How to use it with repository code

Best practice is to paste:

• constructors and destructors
• allocation and deallocation sites
• ownership-transferring APIs
• error-handling branches
• concurrent access points
• FFI boundary code

Those areas expose the lifetime story the skill needs. If you only paste a small happy-path snippet, the output will likely miss the real cleanup hazards.

What to look for in the output

Good output from memory-safety-patterns should:

• name the ownership boundary explicitly
• identify the cleanup trigger
• distinguish unique from shared ownership
• note exception or error-path behavior
• point out when raw pointers are observers rather than owners
• explain tradeoffs, not just prescribe “use smart pointers”

If the answer only says “use Rust” or “use smart pointers everywhere,” prompt again with tighter constraints.

memory-safety-patterns skill FAQ

Is memory-safety-patterns beginner-friendly?

Yes, if you already know the basics of pointers or resources. The skill explains patterns in a way that can help newer engineers, but it is most useful when attached to real code and a real bug risk.

Is this better than an ordinary prompt?

Usually yes for this problem type. A generic prompt often gives shallow advice like “avoid raw pointers.” The memory-safety-patterns skill is more likely to frame the issue around ownership, RAII, lifetime boundaries, and concrete bug categories.

Can I use memory-safety-patterns for Backend Development?

Yes. It fits backend work that includes native services, storage engines, networking layers, extensions, agents, embedded components, or high-performance libraries. It is less relevant for pure CRUD applications on managed runtimes.

Does it only apply to heap memory?

No. One of the practical advantages of memory-safety-patterns is that it naturally extends to resource safety more broadly: file handles, sockets, locks, mapped regions, and other “must release exactly once” resources.

Should I use this instead of sanitizers and compiler checks?

No. Use both. This skill helps you choose safer designs and refactors; sanitizers and compiler tooling help catch violations in actual code paths. They solve different parts of the problem.

Is it mainly for Rust migrations?

Not only. Rust is part of the safety spectrum in the skill, but many users will get value without migrating languages at all. Safer C++ ownership and RAII can remove large classes of bugs in existing systems.

When should I not use memory-safety-patterns?

Do not reach for it when your problem is mostly algorithmic, business-logic driven, or unrelated to ownership and cleanup. It is also a poor fit if you need project-specific build steps or executable tooling from the skill itself.

How to Improve memory-safety-patterns skill

Give the agent an ownership map up front

The fastest way to improve memory-safety-patterns output is to state:

• who allocates
• who frees
• who borrows
• what can outlive what
• what happens on failure

Even a short note like “caller owns buffer; callee borrows until callback returns” can dramatically improve the answer.

Show unsafe paths, not just the happy path

Common failure mode: users share only the main function body. Instead, include:

• early returns
• exceptions
• retries
• partial initialization
• shutdown paths
• concurrent mutation

These are where memory-safety patterns matter most.

Ask for ranked risks before code changes

If you jump straight to refactoring, the answer may optimize style instead of safety. Better prompt:

• “Rank the top memory-safety risks first.”
• “Then propose the smallest change that removes the highest-risk issue.”

This keeps the memory-safety-patterns guide grounded in impact.

Force explicit tradeoff analysis

Ask the model to compare alternatives, for example:

• value semantics vs heap allocation
• unique_ptr vs shared_ptr
• borrow vs own
• staying in C++ vs rewriting the module in Rust

That prevents one-note recommendations and makes adoption decisions easier.

Provide ecosystem constraints clearly

Good constraints improve the usefulness of memory-safety-patterns for Backend Development:

• ABI must remain C-compatible
• no exceptions allowed
• existing API must be preserved
• low-latency path cannot add refcount churn
• team cannot adopt Rust immediately

Without these, the output may be technically safer but operationally unrealistic.

Iterate on the first answer with targeted follow-ups

After the first pass, ask:

• “Where are ownership assumptions still implicit?”
• “Which refactor removes the most risk with the least API churn?”
• “What bugs remain even after this redesign?”
• “Which tests should cover cleanup and lifetime failures?”

This is usually better than requesting a full rewrite.

Watch for common weak-output patterns

Be cautious if the response:

• recommends shared_ptr without justifying shared ownership
• treats raw pointers as always wrong
• ignores stack/value ownership options
• skips error paths
• suggests Rust migration without cost or boundary analysis
• discusses memory safety without naming actual bug classes

These are signs to tighten the prompt and rerun.

Improve with code slices, not whole repos

Large repos dilute the signal. For better memory-safety-patterns usage, isolate:

• one type with ambiguous ownership
• one subsystem with cleanup complexity
• one FFI boundary
• one concurrency-sensitive resource path

Smaller, high-risk slices produce more actionable guidance.

Pair the skill with verification

To improve real outcomes, use the skill to design the fix, then validate with:

• ASan / LSan / TSan
• compiler warnings
• fuzzing for parser or buffer-heavy code
• tests that force failure-path cleanup

That combination turns pattern advice into evidence-backed improvement.