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 agentmods add skills/techymt/claude-code-superpowers/system-boundariesnpx skills add TechyMT/claude-code-superpowers --skill system-boundariesgit clone --depth 1 https://github.com/TechyMT/claude-code-superpowersWhat 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 | $0.00082 | $0.01783 |
| Opus 5 | $0.00041 | $0.00892 |
| Sonnet 5 | $0.00016 | $0.00357 |
| Haiku 4.5 | $0.00008 | $0.00178 |
Grade C, and why
system-boundaries scanned grade C with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Reaches for credential fileshighPrivilege escalation
SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.
The key security detail: Claude Code uses `execFile()` (argument arrays) everywhere, never `exec()` (shell strings). This applies to git, bash helpers, and any other subprocess. A tool input of `"$(cat ~/.ssh/id_rsa)"` w How it starts
The opening of the file, as written. The whole thing — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.
System Boundaries
The pattern
Claude Code has a clear inside/outside line. Inside: the conversation loop, tool execution, state management, permission checking, and UI rendering. Outside: the Claude API (LLM inference), MCP servers (dynamic tool extension), the local file system, the shell, Git, OAuth providers, and remote CCR infrastructure.
The boundary is managed by: the services/api/ module for the Claude API, the services/mcp/ module for MCP clients, sandboxed path resolution for file system access, and execFile wrappers (never exec with shell interpolation) for shell and Git commands.
Why this matters
Each external system has its own failure modes. The Claude API can return 429 (rate limit), timeout, or return malformed tool call JSON. MCP servers can disconnect or return unexpected schemas. The file system can have permission errors or ENOENT. Shell commands can hang or have non-zero exit codes. Git can be absent or on an unexpected version.
By routing all external access through boundary modules (services/api/, services/mcp/, utils/git.ts), error handling and retry logic lives in one place. Tools don't need to handle rate limits or reconnection — they call the boundary, and the boundary handles the failure modes of that external system.
How to apply it
- Claude API: don't call the Anthropic API directly from a tool. Use the services in
services/api/. This gives you automatic retry, token budget tracking, and streaming. - MCP: don't implement a custom MCP client. Use
services/mcp/MCPServerConnection. Register tools viamcpClientsinToolUseContext.options. - File system: always resolve paths through
getResolvedPath()or equivalent — this enforces the sandbox (additional working directories) and prevents path traversal. Usefs.promises(not sync variants). - Shell commands: use
execFileNoThrow()orexecFileSafe()fromutils/bash/— these pass arguments as arrays (not strings), preventing shell injection. Never useexec()with string interpolation. - Git: use
getGitStatus(),getBranch(),getDefaultBranch()fromutils/git.ts— these wrap git inexecFileNoThrowand handle the "not a git repo" case gracefully. - New external service: create a
services/[name]/module, implement error handling for that system's failure modes, and expose a clean interface that tools can call without knowing about HTTP status codes or connection state.
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 · 139 lines · 82 tokens per session scan C 896fc195c5b8
system-boundaries is a skill published in the GitHub repository TechyMT/claude-code-superpowers (5 stars, last pushed 5mo ago), licensed MIT. It adds 82 tokens to every session and 1,783 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it C with 1 finding (reaches for credential files). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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