Borrowing it
Nothing to install: this file belongs to irahardianto/rugged-gemini. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/irahardianto/rugged-gemini/main/.gemini/skills/data-serialization-principles/SKILL.mdgit clone --depth 1 https://github.com/irahardianto/rugged-geminiWrote 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/irahardianto/rugged-gemini/data-serialization-principles)<a href="https://agentmods.dev/skills/irahardianto/rugged-gemini/data-serialization-principles"><img src="https://agentmods.dev/badge/skills/irahardianto/rugged-gemini/data-serialization-principles.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00036 | $0.00356 |
| Opus 5 | $0.00018 | $0.00178 |
| Sonnet 5 | $0.00007 | $0.00071 |
| Haiku 4.5 | $0.00004 | $0.00036 |
Grade A, and why
data-serialization-principles 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 8d 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.
What it actually says
Data Serialization Principles
Validate at Boundaries
All incoming data validated: API requests, file uploads, MQ messages. Type, format, range, required fields. Fail fast on invalid. Clear errors to client.
Encoding
Default UTF-8 everywhere. Specify explicitly when reading/writing. Handle errors gracefully.
Format Selection
| Format | Good For | Limitations |
|---|---|---|
| JSON | APIs, config, web (human-readable, universal) | No binary, larger size |
| Protobuf | Internal microservices, high-throughput (compact, schema evolution) | Not readable, requires schema |
| MessagePack | Internal APIs needing speed over JSON | Less widely supported |
| XML | Enterprise, SOAP, RSS (legacy) | Verbose, XXE attacks |
| YAML | Config, IaC (K8s, CI/CD) (human-friendly) | Complex parsing, security risks |
Security
- Validate before deserialization (prevent arbitrary code execution)
- Size limits on payloads (prevent OOM)
- Whitelist allowed types/classes
- XML: disable external entities (XXE)
- YAML: disable unsafe constructors
- Python pickle: NEVER deserialize untrusted data
Related
- Error Handling GEMINI.md § Error Handling Principles
- Security Mandate GEMINI.md § Security Mandate
- Security Principles GEMINI.md § Security Principles
- API Design @.gemini/skills/api-design-principles/SKILL.md
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.
- 8d ago First seen · 40 lines · 36 tokens per session scan A 5e43cef96f29
data-serialization-principles is a skill published in the GitHub repository irahardianto/rugged-gemini (5 stars, last pushed 3mo ago), licensed MIT. It adds 36 tokens to every session and 356 once invoked, about $0.0002 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.
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