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prompts/docs/architecture.md
John Lancaster 0a9dadd5a8 ruff skill
2026-06-20 17:25:47 -05:00

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icon: lucide/library
---
# Architecture
## Overview
The platform is implemented as a resource-first MCP system with an integrated static documentation surface. The same methodology content powers both MCP resources and the published docs site.
An MCP server is a runtime that exposes machine-readable resources and tools through stable interfaces so AI clients can discover and consume context consistently. Here, the server's role is intentionally narrow: publish canonical methodology documents as resources, keep discovery predictable through a catalog layer, and serve the same source material as pre-built static documentation.
The system is complete in three layers:
1. Canonical methodology is maintained in Markdown skill documents.
2. Catalog resources provide normalized discovery.
3. Zensical builds a static site from those same Markdown sources and the FastAPI app serves it in the FastMCP runtime process.
This architecture is anchored by three contracts:
1. Docs-first authored content contract under `docs/` with strict per-skill ownership.
2. `SKILL.md` frontmatter contract with Anthropic fields plus `x-personal-mcp` metadata.
3. Canonical resource URI contract with break-and-replace policy for contract changes.
Detailed contract pages:
1. [Content Contract](./content.md)
2. [Frontmatter Contract](./frontmatter.md)
3. [URI Contract](./uris.md)
This architecture keeps authored content human-friendly while preserving machine-stable contracts.
## Intent
The architecture is designed to satisfy three long-term requirements:
1. Methodology must be editable as markdown by humans.
2. Agents must consume stable, discoverable resource contracts, with a minimal read-only catalog tool fallback for constrained clients.
3. Public documentation must be pre-built static output served from the application runtime without a separate docs service.
## System Model
### Pattern Modules
Each skill encapsulates one methodology domain in a docs-owned directory:
1. `docs/skills/<skill-id>/SKILL.md`
2. `docs/skills/<skill-id>/references/...`
The skill document and references are the authored source of truth; runtime code indexes and serves these files without becoming a second authored source.
Each skill publishes resource families:
1. document
The document resource returns canonical Markdown, while clients can perform any downstream section extraction they need.
### Catalog Module
The catalog is the canonical discovery layer and publishes normalized records for all modules. It may also expose a minimal set of read-only discovery tools that resolve back to the same canonical markdown content when a client chat surface does not expose MCP resource attachment.
Typical catalog resources:
1. resource://catalog/skills_index
2. resource://catalog/skills/{skill_id}
Only canonical catalog resources are part of the runtime contract in this phase.
### Registry Loader
The runtime composition includes a startup registry loader that reads packaged docs resources using `importlib.resources.files(...)` and `Traversable` APIs.
Loader responsibilities:
1. Parse SKILL.md frontmatter for each skill.
2. Validate schema and cross-field constraints before any resource registration.
3. Build an in-memory registry keyed by `skill_id`.
4. Fail fast for duplicate ids, missing markdown files, broken reference mappings, and invalid `depends_on` values.
Registry load failure is a startup error, not a partial runtime warning.
### Content Sources
Content is authored in markdown under `docs/` and managed as long-form reference material. Skill documents and companion references now live under `docs/skills/`, while project-authored pages remain alongside them in the docs tree. Resource handlers expose the same authored documents through stable resource URIs.
### Static Docs Surface
Static docs are built directly from two markdown source streams:
1. Project-authored docs pages
2. Skill and reference markdown pages
The merged docs tree is built by Zensical into static files and served by the FastAPI app.
## Data Flow
```mermaid
flowchart TD
A[Authored Markdown] --> C[Resource Handlers]
B[Pattern Metadata] --> D[Catalog Resources]
A --> E[Zensical Static Build]
E --> H[FastAPI Static Mount]
H --> I[Served Docs Site]
D --> I
```
## Contracts
### Metadata Contract
Each skill declares frontmatter in `docs/skills/<skill-id>/SKILL.md`.
For the full field-level contract, validation model, and FastMCP metadata mapping, see [Frontmatter Contract](./frontmatter.md).
Anthropic-facing required fields:
1. name
2. description
Repository indexing metadata is declared in `x-personal-mcp`:
1. id
2. version
3. tags
4. capabilities
5. depends_on
6. optional references map (for nested entries, overrides, and aliases)
No `metadata.yaml` sidecar is part of the end-state contract.
### URI Contract
Canonical resource URIs are:
For the full URI semantics, parameter validation rules, and compatibility policy, see [URI Contract](./uris.md).
1. resource://skills/<skill_id>/document
2. resource://skills/<skill_id>/references/<ref_id>
3. resource://catalog/skills_index
4. resource://catalog/skills/{skill_id}
5. resource://docs/{path*}
Validation rules:
1. `skill_id` is lowercase kebab-case and must satisfy the stable skill id contract.
2. `ref_id` is lowercase kebab-case and must resolve from either:
- top-level auto-discovery of `references/*.md` filename stems, or
- an explicit `x-personal-mcp.references` entry.
3. `path*` resolves only to normalized markdown paths under `docs/`.
### Resource Registration Contract
Resources are registered from the validated registry, not by ad hoc per-skill hardcoding.
Registration rules:
1. Use RFC6570 URI templates where appropriate.
2. Mark documentation resources as read-only and idempotent.
3. Set explicit mime types for resource responses.
4. Configure duplicate URI handling with `on_duplicate="error"` for startup safety.
This keeps runtime behavior deterministic and prevents accidental URI collisions.
### Versioning Rule
URIs are unversioned and canonical in this phase.
1. Breaking URI changes are handled as direct replacement.
2. No compatibility aliases or dual URI families are maintained.
## Static Hosting Pattern
The docs site is pre-built and served by the same FastAPI runtime process used by the MCP app.
Runtime behavior:
1. App starts.
2. FastAPI mounts the static docs output directory.
3. Requests to docs paths are served as static assets.
This provides a single deployment artifact with no runtime markdown rendering dependency.
## Advantages
### Single Source of Truth
Methodology is authored once and reused in both MCP resources and docs pages.
### High-Fidelity Agent Context
Resources expose the same canonical Markdown that humans author and review.
### Operational Simplicity
A single app process serves MCP and docs surfaces.
### Long-Term Maintainability
Markdown remains easy to review, while contracts remain stable for clients.
### Client Independence
Clients can use Ask, Edit, or Agent modes without requiring server-owned prompt orchestration. However, MCP affordances are still chat-surface-dependent: some clients or sessions expose resource attachment directly, while others make tool invocation the more reliable retrieval path.
## Authoring and Publishing Lifecycle
1. Update markdown reference content.
2. Update metadata if capability surface changes.
3. Build static docs with Zensical.
4. Serve built output through FastAPI static mount.
## Scope and Non-Goals
In-scope:
1. Resource-first methodology delivery
2. Catalog-based discovery
3. Pre-built static docs hosting in app runtime
Out-of-scope:
1. Prompt-first orchestration as the primary interface
2. Large tool inventories duplicating static guidance across skill modules
3. Separate dynamic docs service at runtime
Allowed exception:
1. A small catalog-level tool layer is acceptable when it improves client interoperability without creating a second source of truth for skill content.
## Example Content Inputs
Existing markdown reference sets are valid examples of authored source material for this architecture:
1. docs/skills/pytest-scaffolding/references/pytest-docs.md
2. docs/skills/python-logging-dictconfig/references/python-logging-docs.md
3. docs/skills/fastapi-uv-docker/references/fastapi-best-practices.md
These inputs are treated as content sources, while resource URIs and catalog payloads remain the machine-facing contracts.