extension-data-providers

name	Extension: Data Providers
description	PageDataProvider, ContentDataProvider, and FrontmatterProcessor trait implementations

Extension: Data Providers

Data providers inject dynamic content into pages, enrich content items, and process frontmatter metadata. All traits live in crates/shared/provider-contracts/src/.

---

1. PageDataProvider

Injects JSON data into page templates during rendering.

Trait

#[async_trait]
pub trait PageDataProvider: Send + Sync {
    fn applies_to_pages(&self) -> Vec<String>;
    async fn provide_page_data(&self, ctx: &dyn PageDataContext) -> Result<Value>;
    fn priority(&self) -> u32;
}

Implementation

pub struct MyPageDataProvider;

#[async_trait]
impl PageDataProvider for MyPageDataProvider {
    fn applies_to_pages(&self) -> Vec<String> {
        vec!["homepage".into(), "blog".into()]
    }

    async fn provide_page_data(&self, ctx: &dyn PageDataContext) -> Result<Value> {
        let site = ctx.site_config();
        Ok(serde_json::json!({
            "hero_title": site.name,
            "featured_count": 5
        }))
    }

    fn priority(&self) -> u32 { 100 }
}

Registration

impl Extension for MyExtension {
    fn page_data_providers(&self) -> Vec<Arc<dyn PageDataProvider>> {
        vec![Arc::new(MyPageDataProvider)]
    }
}

Priority

Lower values execute first. Multiple providers for the same page merge their data. Later providers can override earlier keys.

---

2. ContentDataProvider

Enriches content items with computed fields during ingestion.

Trait

#[async_trait]
pub trait ContentDataProvider: Send + Sync {
    fn applies_to_sources(&self) -> Vec<String>;
    async fn enrich_content(&self, ctx: &dyn ContentDataContext, item: &mut ContentItem) -> Result<()>;
    fn priority(&self) -> u32;
}

Implementation

pub struct ReadingTimeProvider;

#[async_trait]
impl ContentDataProvider for ReadingTimeProvider {
    fn applies_to_sources(&self) -> Vec<String> {
        vec!["blog".into(), "docs".into()]
    }

    async fn enrich_content(&self, _ctx: &dyn ContentDataContext, item: &mut ContentItem) -> Result<()> {
        let word_count = item.body.split_whitespace().count();
        let reading_time = (word_count / 200).max(1);
        item.metadata.insert("reading_time_minutes".into(), reading_time.into());
        Ok(())
    }

    fn priority(&self) -> u32 { 100 }
}

Registration

impl Extension for MyExtension {
    fn content_data_providers(&self) -> Vec<Arc<dyn ContentDataProvider>> {
        vec![Arc::new(ReadingTimeProvider)]
    }
}

---

3. FrontmatterProcessor

Validates and transforms YAML frontmatter before content ingestion.

Trait

#[async_trait]
pub trait FrontmatterProcessor: Send + Sync {
    fn applies_to_sources(&self) -> Vec<String>;
    async fn process_frontmatter(&self, ctx: &dyn FrontmatterContext) -> Result<()>;
    fn priority(&self) -> u32;
}

Standard Frontmatter Fields

---
title: "Article Title"
slug: "article-title"
description: "Short description"
author: "systemprompt"
published_at: "2024-01-01"
type: "skill"
category: "skills"
keywords: "comma, separated, keywords"
kind: article
---

Processing Order

1. FrontmatterProcessors run in priority order (lowest first)
2. ContentDataProviders enrich after frontmatter is finalized
3. PageDataProviders inject data at render time

---

4. Rules

Rule	Rationale
All providers must be Send + Sync	Providers run in async contexts across threads
Return Result, never panic	Ingestion must continue even if one provider fails
Use typed identifiers	SourceId, CategoryId from systemprompt_identifiers
Log with tracing, never println!	Consistent with Rust standards
Priority 100 for extensions	Core providers use 1-50. Extensions start at 100.