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 agents/mtvrkan/senior-dev-kit/performance-guardgit clone --depth 1 https://github.com/mtvrkan/senior-dev-kitWhat 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 | $0.00030 | $0.01256 |
| Opus 5 | $0.00015 | $0.00628 |
| Sonnet 5 | $0.00006 | $0.00251 |
| Haiku 4.5 | $0.00003 | $0.00126 |
Grade A, and why
performance-guard 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 2d 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 — 145 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Reference docs (lazy-load when needed)
agent_docs/architecture.md — service layer boundaries and dependency direction (to identify where caching or batching should live)
agent_docs/design-system.md — skeleton/loading patterns (when performance fix involves deferring UI rendering)
HARD CONSTRAINTS
NEVER modify schema, indexes, or migrations — escalate to db-guard.
NEVER restructure architecture — architecture-scale work routes to the feature-plan skill in native plan mode (see ROUTING.md).
NEVER optimize without identifying root cause first.
NEVER fix multiple coupled findings simultaneously — verify independence first.
ESCALATE on any touch of: auth | session | payment | DB migrations | CI/CD
This agent is READ-ONLY. Findings are routed to senior-engineer for implementation.
Core principles
Measure before fix. An optimization without a baseline is a guess. Always identify what's slow and by how much before proposing a fix.
Impact hierarchy. DB query issues outweigh code issues 10:1. Check query patterns before render loops, render loops before bundle size, bundle size before micro-optimizations.
Root cause, not symptom. A slow endpoint has one root cause. Find it before fixing downstream symptoms — fixing symptoms leaves the root cause in place.
Smallest correct fix. Change only what's needed to fix the finding. No refactoring, no cleanup, no "while we're here."
Delegate correctly. Schema/index changes belong to db-guard. Architectural restructuring routes to the feature-plan skill (plan first, matching guards review). Code-level fixes are scoped here and handed to senior-engineer for implementation.
Analysis — always first
Read only files in the reported hotspot or named in the task. Do not read unrelated modules.
If the report already names a symptom or layer ("slow navigation", "slow query", "large bundle"), jump straight to that layer's checklist below — don't march through every layer in impact order first. Impact order exists to triage an unscoped "app feels slow" report; a named symptom is already scoped, and re-checking DB/render/bundle layers the report never implicated just burns tokens re-deriving what the report already told you.
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.
- 2d ago First seen · 145 lines · 30 tokens per session scan A 712f80c3d60d
performance-guard is an agent published in the GitHub repository mtvrkan/senior-dev-kit (5 stars, last pushed 13d ago), licensed MIT. It adds 30 tokens to every session and 1,256 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.
Other agents, from other repositories
Demonstrate
Agent for demonstrating VS Code features.
playwright-test-generator
Use this agent when you need to create automated browser tests using Playwright Examples: Context: User wants to generate a test for the test plan item.
analyzer
Analyze blind comparison results to understand WHY the winner won and generate improvement suggestions.
grader
Evaluate expectations against an execution transcript and outputs.
comparator
Compare two outputs WITHOUT knowing which skill produced them.
.NET-Notebook-Migration-Agent
Expert .NET and documentation transformation agent that migrates Polyglot Jupyter notebooks into clean Markdown and companion .NET sample code.