Security boundaries — GRIDA-SEC

What GRIDA-SEC-<id> means

Each GRIDA-SEC-<id> is a prevented vulnerability — a class of attack that would exist by default but the codebase structurally forecloses. Unlike a CVE (which describes something that was broken), a GRIDA-SEC id is a contract: this specific class of attack is impossible because of these specific files, and we keep it that way.

/SECURITY.md is the canonical registry. Every id has a section there with:

• What it protects — the boundary in plain English.
• Vulnerable scenario — the attack that would exist without the boundary.
• How the code prevents it — the enforcement mechanism, file by file.
• Files bound by this id — the exact files whose contents make up the contract.

Working with tagged code

When you see GRIDA-SEC-<id> in a file you're touching:

1. Read the entry in /SECURITY.md for that id. Don't act on the tag alone — the rules are spelled out there.
2. Run grep -rn GRIDA-SEC-<id> . to find every other file in the contract. Changes that look local often aren't — a tagged file is load-bearing for the boundary.
3. Don't remove a tag without removing the entry from /SECURITY.md in the same change, with a written justification.

Mandatory security review before commit

If your change touches any file containing a GRIDA-SEC-<id> tag, you must complete a security review before committing. The review is brief but explicit:

1. Re-read the entry in /SECURITY.md for every GRIDA-SEC-<id> that appears in your diff. Confirm the prevented scenario is still prevented after your change.
2. Walk the enforcement mechanism. For each numbered "How the code prevents it" step in the entry, point at the line in your diff (or confirm it's untouched) that satisfies that step.
3. Verify all tagged files are still tagged. A rename, refactor, or move that drops the tag is a contract violation, even if behavior looks identical.
4. If you added or removed a file from the boundary, update the "Files bound by this id" list in /SECURITY.md in the same commit.
5. Run any tests adjacent to the boundary. The SECURITY.md entry for the id may list specific tests; use grep -rn GRIDA-SEC-<id> --include='*test*' --include='*spec*' to find any others.

If you cannot satisfy steps 1–4, do not commit. Either revert the change, or explicitly amend the SECURITY.md entry to reflect a deliberate update of the contract — and surface that to the user.

Adding a new GRIDA-SEC id

When you introduce a new structural prevention worth tracking:

1. Allocate the next sequential id. Look at /SECURITY.md, find the highest existing GRIDA-SEC-NNN, use NNN+1. Don't reuse retired ids; don't renumber.
2. Write the entry in /SECURITY.md under "Active boundaries". Use the same four-section shape as existing ids: What it protects / Vulnerable scenario / How the code prevents it / Files bound.
3. Tag every relevant file. Header comment in source files, callout block in READMEs, comment in scripts. Use the literal string GRIDA-SEC-NNN. Brief inline tags at specific code locations are fine too (e.g. // GRIDA-SEC-NNN: rule 2 — fail closed).
4. Verify the grep works. grep -rn GRIDA-SEC-NNN . should return the entry in /SECURITY.md plus every tagged file.

This skill auto-loads on any "GRIDA-SEC" mention via its description. You don't need to register a new id with the skill.

When NOT to use this convention

• Implementation bugs that were once exploitable. Those are CVE territory. GRIDA-SEC is for prevented-by-structure classes — if a bug happened, write a postmortem, not a GRIDA-SEC.
• Generic best practices (input validation, authn/authz on user routes, etc.). Those are baseline and don't need an id. Reserve GRIDA-SEC for specific structural decisions where misunderstanding the design would re-open a class of attack.
• Per-feature security notes that aren't structural contracts. Those go in the feature's own docs.

A good test: if you can reasonably write "this attack class is impossible because…" in one paragraph and grep returns ≥2 files that together make it true, it's a candidate for GRIDA-SEC.