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 athola/claude-night-market --skill architecture-paradigm-functional-coregit clone --depth 1 https://github.com/athola/claude-night-marketWrote 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/athola/claude-night-market/architecture-paradigm-functional-core)<a href="https://agentmods.dev/skills/athola/claude-night-market/architecture-paradigm-functional-core"><img src="https://agentmods.dev/badge/skills/athola/claude-night-market/architecture-paradigm-functional-core/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/athola/claude-night-market/architecture-paradigm-functional-core"><img src="https://agentmods.dev/badge/skills/athola/claude-night-market/architecture-paradigm-functional-core.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00040 | $0.01025 |
| Opus 5 | $0.00020 | $0.00513 |
| Sonnet 5 | $0.00008 | $0.00205 |
| Haiku 4.5 | $0.00004 | $0.00103 |
Grade A, and why
architecture-paradigm-functional-core 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 9d 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 — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.
The Functional Core, Imperative Shell Paradigm
When To Use
- Separating pure business logic from side effects
- Improving testability through immutable domain models
When NOT To Use
- Performance-critical hot paths where immutability overhead matters
- Purely imperative codebases with no plans to adopt functional patterns
When to Employ This Paradigm
- When business logic is entangled with I/O operations (e.g., database calls, HTTP requests), making tests brittle and slow.
- When significant development time is spent rewriting adapters or dealing with framework churn.
- When you require a suite of fast, deterministic unit tests that operate on plain data, complemented by a thin integration testing layer.
Adoption Steps
- Inventory Side Effects: Create a map of all side effects in the system, such as database writes, external API calls, UI events, and filesystem access. Explicitly assign these responsibilities to the "shell."
- Model the Core Logic: Represent business rules and policies as pure functions. These functions should take domain data as input and return decisions or commands as output, avoiding shared mutable state.
- Design the Command Schema: Define a small, explicit set of command objects that the core can return and the shell can interpret (e.g.,
PersistOrder,PublishEvent,NotifyUser). - Refactor Incrementally: Begin with high-churn or critical modules. Wrap legacy imperative code behind adapters while progressively extracting pure calculations into the functional core.
- Enforce Boundaries: Use code reviews and automated architecture tests to validate a strict separation. The shell should only handle orchestration, sequencing, and retries, while the core should never call directly into frameworks or I/O libraries.
Key Deliverables
- An Architecture Decision Record (ADR) detailing why this pattern was chosen, which modules are affected, and the scope of the migration.
- A suite of unit tests for the core with high (>90%) and deterministic code coverage. Where applicable, use property-based or fixture-based testing to cover a wide range of inputs.
- A suite of contract and integration tests for the shell that verify correct command interpretation, retry logic, and telemetry.
- A set of rollout metrics (e.g., deployment lead time, incident rate in the shell layer) to demonstrate the value of the architectural change.
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.
- 9d ago First seen · 86 lines · 40 tokens per session scan A 6cc43f7f9f06
architecture-paradigm-functional-core is a skill published in the GitHub repository athola/claude-night-market (337 stars, last pushed 2d ago), licensed MIT. It adds 40 tokens to every session and 1,025 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 2026-09-03.
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