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 a-ariff/ariff-claude-plugins --skill defense-in-depthgit clone --depth 1 https://github.com/a-ariff/ariff-claude-pluginsWrote 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/a-ariff/ariff-claude-plugins/defense-in-depth)<a href="https://agentmods.dev/skills/a-ariff/ariff-claude-plugins/defense-in-depth"><img src="https://agentmods.dev/badge/skills/a-ariff/ariff-claude-plugins/defense-in-depth/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/a-ariff/ariff-claude-plugins/defense-in-depth"><img src="https://agentmods.dev/badge/skills/a-ariff/ariff-claude-plugins/defense-in-depth.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00014 | $0.00843 |
| Opus 5 | $0.00007 | $0.00421 |
| Sonnet 5 | $0.00003 | $0.00169 |
| Haiku 4.5 | $0.00001 | $0.00084 |
Grade A, and why
defense-in-depth 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 10d 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 — 165 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Defense in Depth
Philosophy
MULTIPLE INDEPENDENT VALIDATION LAYERS
Each layer catches what others miss
One check can fail silently. Four layers rarely do.
The Four Layers
Layer 1: Type/Syntax
What: Static analysis, types, linting
Catches: Typos, syntax errors, type mismatches
Run: First, before anything else
Layer 2: Unit Tests
What: Individual function/module tests
Catches: Logic errors, edge cases, regressions
Run: After each code change
Layer 3: Integration Tests
What: Component interaction tests
Catches: Interface mismatches, data flow errors
Run: After unit tests pass
Layer 4: End-to-End
What: Full system tests, user scenarios
Catches: Missing requirements, workflow bugs
Run: Before claiming complete
The Pipeline
Code Change
↓
[Layer 1: Lint/Type Check]
↓ PASS?
[Layer 2: Unit Tests]
↓ PASS?
[Layer 3: Integration Tests]
↓ PASS?
[Layer 4: E2E / Manual Check]
↓ PASS?
Done
Fail at any layer → FIX before proceeding
Why Every Layer Matters
| Without This Layer | What Escapes |
|---|---|
| No type checks | Undefined calls crash at runtime |
| No unit tests | Logic bugs slip through |
| No integration | Components don't work together |
| No E2E | User workflows broken |
Implementation Patterns
For Code Changes
1. Make change
2. Run linter immediately
3. Run affected unit tests
4. Run integration suite
5. Test the actual feature
For Bug Fixes
1. Write failing test first
2. Fix the bug
3. Run all tests (regression check)
4. Verify original symptom gone
For New Features
1. Write unit tests for new logic
2. Implement feature
3. Add integration tests
4. Verify against requirements
Layer-Specific Commands
Configure per project:
layer_1:
command: "npm run lint && npm run typecheck"
when: "On save, before commit"
layer_2:
command: "npm run test:unit"
when: "After code changes"
layer_3:
command: "npm run test:integration"
when: "After unit tests pass"
layer_4:
command: "npm run test:e2e"
when: "Before claiming done"
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.
- 10d ago First seen · 165 lines · 14 tokens per session scan A 5480f7905cc5
defense-in-depth is a skill published in the GitHub repository a-ariff/ariff-claude-plugins (14 stars, last pushed 5mo ago), licensed MIT. It adds 14 tokens to every session and 843 once invoked, about $0.0001 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 2026-08-30.
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