build-falco-web-app

build-falco-web-app is a skill for Claude Code, Codex from gaelic-ghost/socket. It costs 42 tokens per session (422 once invoked), scanned A, original, Apache-2.0.

A development guide for Falco, an F# web framework built on ASP.NET Core. It covers request handling, responses, configuration, security controls, and tests while keeping application logic separate from web code.

In plain words
What is it for?
Use it to build or change Falco web applications, add routes and validation, configure the ASP.NET Core host, and test domain logic and endpoints.
Why use it?
It helps keep routes readable and business rules testable instead of mixing them with HTTP, authentication, or HTML handling.

Skill for Claude CodeCodex

Part of the dotnet-skills plugin — 12 skills shipped together

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 skills/gaelic-ghost/socket/build-falco-web-app
Any agent
npx skills add gaelic-ghost/socket --skill build-falco-web-app
Clone the repo
git clone --depth 1 https://github.com/gaelic-ghost/socket

Made for: Claude Code, Codex.

Or install dotnet-skills, the plugin that ships this one along with the rest of its 12 skills.

Wrote 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.

agentmods badge for build-falco-web-app

README.md
[![agentmods](https://agentmods.dev/badge/skills/gaelic-ghost/socket/build-falco-web-app.svg)](https://agentmods.dev/skills/gaelic-ghost/socket/build-falco-web-app)
Your own site
<a href="https://agentmods.dev/skills/gaelic-ghost/socket/build-falco-web-app"><img src="https://agentmods.dev/badge/skills/gaelic-ghost/socket/build-falco-web-app.svg" alt="Measured on agentmods" height="20"></a>
Per session 42 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 422 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 $0.00042 $0.00422
Opus 5 $0.00021 $0.00211
Sonnet 5 $0.00008 $0.00084
Haiku 4.5 $0.00004 $0.00042

Measured yesterday against content hash 624d0200ec93, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

build-falco-web-app 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 yesterday.

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.

plugins/dotnet-skills/skills/build-falco-web-app/SKILL.md · 49 lines

What it actually says

Build Falco Web App

Use Falco for its lightweight functional HTTP surface while leaving business behavior as ordinary, testable F# code.

Source Check

Read existing routes, the web host, project references, tests, and configuration before editing. Consult Falco's source and documentation and ASP.NET Core documentation for current package behavior.

Workflow

  1. Confirm Falco is the selected framework; otherwise start with dotnet:choose-fsharp-web-framework.
  2. Define route handlers around one request job. Parse input, call a domain function, then write one explicit response shape.
  3. Keep routing declarative and readable. Split route groups by feature instead of building one mutable registration surface.
  4. Use the existing ASP.NET Core host for configuration, dependency registration, authentication, authorization, logging, and rate or upload limits. Do not hide those platform concerns in unrelated response helpers.
  5. Treat HTML/view code as presentation. Keep it separate from request parsing, authorization, and persistence behavior.
  6. Test domain modules without a host, then add endpoint or integration coverage for routes, input validation, auth decisions, and response contracts.

Validation

Run the repository's targeted commands. If it has none, use:

dotnet build <web-project.fsproj>
dotnet test <test-project.fsproj>

Boundaries

  • Preserve F# compile order and explicit task or async boundaries.
  • Do not translate C# controller or service patterns mechanically into Falco.
  • For Azure resources, hosting, monitoring, identity, or deployment, use the official Azure Skills handoff rather than inventing provider commands here.
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. yesterday First seen · 49 lines · 42 tokens per session scan A 624d0200ec93

Subscribe to this mod's changes

build-falco-web-app is a skill published in the GitHub repository gaelic-ghost/socket (7 stars, last pushed 9d ago), licensed Apache-2.0. It adds 42 tokens to every session and 422 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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