Architecture: Plugin and Content Extraction

This overview reflects the current implementation of the plugin stack and content extraction pipeline. Every item below maps directly to production code.

For the user-facing plugin guide (writing and configuring plugins), see Plugins.

Manifests and Capability Negotiation

Source: src/daemon/resource/plugin_loader.cpp

• PluginLoader::loadPlugin opens a shared object, probes exported functions such as getProviderName, createOnnxProvider, and createGraphAdapterV1, and records which interfaces the plugin implements.
• Manifests declared in docs/spec/plugin_metadata.schema.json describe versioning and required capabilities; loader logic validates the manifest against this schema before registering providers.
• Graph adapter factories are tracked in an in-process registry via registerGraphAdapter / createGraphAdapter so knowledge-graph integrations can be selected at runtime.

Trust and Admission

Source: src/daemon/resource/plugin_host.cpp

• PluginHost::trust/untrust maintain a canonicalized allow-list persisted alongside the daemon data directory.
• PluginHost::enumerateTrusted filters discovered libraries against that list, which ServiceManager::autoloadPluginsNow uses to decide which plugins can be materialized.

Native ABI Loader

Source: src/daemon/resource/abi_plugin_loader.cpp

• Resolves ABI entry points, maps them to C++ adapter classes, and converts plugin callbacks into daemon-facing interfaces (storage, model providers, etc.).
• Handles symbol version mismatches and throws structured errors that bubble back to the caller.

Content Extraction Pipeline

Content extraction is driven by plugins implementing the content_extractor_v1 interface. The daemon coordinates extraction during ingestion:

1. Plugin discovery: The daemon scans for extractors via PluginLoader at startup, matching file types to capable plugins.
2. Extraction dispatch: During add/ingest, the PostIngestQueue dispatches documents to registered extractors based on MIME type (e.g., PDF extractor, tree-sitter symbol extractor).
3. Symbol extraction: The tree-sitter plugin (plugin-symbols) parses source files and emits function/class/import definitions into the knowledge graph, enabling symbol-aware search.
4. PDF extraction: The PDF extractor plugin uses qpdf/poppler to extract text content, which is then indexed for full-text and vector search.

Plugin Interfaces

Interface	Purpose	Entry points
Model provider	Embedding generation (ONNX)	createOnnxProvider, getProviderName
Graph adapter	Knowledge graph backend	createGraphAdapterV1
Content extractor	Text/symbol extraction	content_extractor_v1 ABI
Search provider	Plugin-contributed search results	search_provider_v1 ABI
Storage plugin	Object storage backends (S3/R2)	See Storage Plugin v1