priority: critical

Plugin Architecture & Registration

Plugin Types

DocumentExtractor: Plugin

plugins/extractor/trait.rs

OcrBackend: Plugin

plugins/ocr/trait.rs

PostProcessor: Plugin

plugins/processor/trait.rs

Validator: Plugin

plugins/validator/trait.rs

DocumentExtractor Implementation

use crate::plugins::{DocumentExtractor, Plugin};
use async_trait::async_trait;

pub struct MyExtractor;

impl Plugin for MyExtractor {
    fn name(&self) -> &str { "my-extractor" }
    fn version(&self) -> String { env!("CARGO_PKG_VERSION").to_string() }
}

#[async_trait]
impl DocumentExtractor for MyExtractor {
    async fn extract_bytes(&self, content: &[u8], mime_type: &str, config: &ExtractionConfig)
        -> Result<ExtractionResult> { /* ... */ }

    fn supported_mime_types(&self) -> &[&str] { &["application/x-custom"] }
    fn priority(&self) -> i32 { 50 }

    // WASM support (optional)
    fn as_sync_extractor(&self) -> Option<&dyn SyncExtractor> { None }
}

Priority System

Registry selects highest priority extractor for each MIME type. Override built-ins with priority > 50.

Registration

// In extractors/mod.rs → register_default_extractors()
let registry = get_document_extractor_registry();
let mut registry = registry.write()
    .map_err(|e| KreuzbergError::Other(format!("Registry lock poisoned: {}", e)))?;
registry.register(Arc::new(MyExtractor::new()))?;

Feature-Gated Registration

#[cfg(feature = "office")]
{
    registry.register(Arc::new(DocxExtractor::new()))?;
    registry.register(Arc::new(PptxExtractor::new()))?;
}

PostProcessor Pattern

impl PostProcessor for MyProcessor {
    async fn process(&self, result: &mut ExtractionResult, config: &ExtractionConfig)
        -> Result<()> {
        result.content = process_content(&result.content);
        Ok(())
    }
    fn stage(&self) -> ProcessorStage { ProcessorStage::Middle }
}

Stages:

Early

Middle

Late

Critical Rules

1. All plugins MUST be

   Send + Sync

2. Feature gate with

   #[cfg(feature = "...")]

   for optional formats
3. Use

   #[async_trait]

   for

   DocumentExtractor

4. Initialization via

   ensure_initialized()

   (lazy, called before first extraction)
5. Plugin names: kebab-case (e.g.,

   "pdf-extractor"

   )