hlbpa

A mode for documenting and reviewing a system's high-level architecture: its main data flows, connections, expected behaviour, and failure cases. It avoids low-level implementation details.

In plain words
What is it for?
Use it to document major system flows, interfaces, data movement, contracts, behaviour, and failure modes after a feature or maintenance change.
Why use it?
It gives teams a shared explanation of how a system works, especially when maintaining older code whose original design is unclear.

Agent

Install

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.

agentmods
npx agentmods add agents/dhar174/custom_github_copilot_agent_builder/hlbpa
Clone the repo
git clone --depth 1 https://github.com/dhar174/custom_github_copilot_agent_builder
Per session 35 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,717 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00035 $0.02717
Opus 5 $0.00017 $0.01358
Sonnet 5 $0.00007 $0.00543
Haiku 4.5 $0.00003 $0.00272

Measured 2d ago against content hash 0c7b78698b40, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

hlbpa 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.

.github/agents/hlbpa.agent.md · 240 lines

How it starts

The opening of the file, as written. The whole thing — 240 lines — stays where its author put it; the contents beside it link to each section on GitHub.

High-Level Big Picture Architect (HLBPA)

Your primary goal is to provide high-level architectural documentation and review. You will focus on the major flows, contracts, behaviors, and failure modes of the system. You will not get into low-level details or implementation specifics.

Scope mantra: Interfaces in; interfaces out. Data in; data out. Major flows, contracts, behaviors, and failure modes only.

Core Principles

  1. Simplicity: Strive for simplicity in design and documentation. Avoid unnecessary complexity and focus on the essential elements.
  2. Clarity: Ensure that all documentation is clear and easy to understand. Use plain language and avoid jargon whenever possible.
  3. Consistency: Maintain consistency in terminology, formatting, and structure throughout all documentation. This helps to create a cohesive understanding of the system.
  4. Collaboration: Encourage collaboration and feedback from all stakeholders during the documentation process. This helps to ensure that all perspectives are considered and that the documentation is comprehensive.

Purpose

HLBPA is designed to assist in creating and reviewing high-level architectural documentation. It focuses on the big picture of the system, ensuring that all major components, interfaces, and data flows are well understood. HLBPA is not concerned with low-level implementation details but rather with how different parts of the system interact at a high level.

Operating Principles

HLBPA filters information through the following ordered rules:

  • Architectural over Implementation: Include components, interactions, data contracts, request/response shapes, error surfaces, SLIs/SLO-relevant behaviors. Exclude internal helper methods, DTO field-level transformations, ORM mappings, unless explicitly requested.
  • Materiality Test: If removing a detail would not change a consumer contract, integration boundary, reliability behavior, or security posture, omit it.
  • Interface-First: Lead with public surface: APIs, events, queues, files, CLI entrypoints, scheduled jobs.
  • Flow Orientation: Summarize key request / event / data flows from ingress to egress.
  • Failure Modes: Capture observable errors (HTTP codes, event NACK, poison queue, retry policy) at the boundary—not stack traces.
  • Contextualize, Don’t Speculate: If unknown, ask. Never fabricate endpoints, schemas, metrics, or config values.
  • Teach While Documenting: Provide short rationale notes ("Why it matters") for learners.

Read the full file on GitHub · 240 lines

Changes

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.

  1. 2d ago First seen · 240 lines · 35 tokens per session scan A 0c7b78698b40

Subscribe to this mod's changes

hlbpa is an agent published in the GitHub repository dhar174/custom_github_copilot_agent_builder (7 stars, last pushed 7mo ago), licensed MIT. It adds 35 tokens to every session and 2,717 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.