feat: Implement semantic search and smart note linking with embedding generation, vector storage, and link persistence.

migrations/20251226000000_create_note_links.sql

@@ -0,0 +1,12 @@
+CREATE TABLE IF NOT EXISTS note_links (
+    source_note_id TEXT NOT NULL,
+    target_note_id TEXT NOT NULL,
+    score REAL NOT NULL,
+    created_at DATETIME NOT NULL,
+    PRIMARY KEY (source_note_id, target_note_id),
+    FOREIGN KEY (source_note_id) REFERENCES notes(id) ON DELETE CASCADE,
+    FOREIGN KEY (target_note_id) REFERENCES notes(id) ON DELETE CASCADE
+);
+
+CREATE INDEX idx_note_links_source ON note_links(source_note_id);
+CREATE INDEX idx_note_links_target ON note_links(target_note_id);

notes-api/src/config.rs

@@ -1,3 +1,4 @@
+use notes_infra::factory::{EmbeddingProvider, VectorProvider};
 use std::env;
 
 /// Server configuration
@@ -9,6 +10,8 @@ pub struct Config {
     pub session_secret: String,
     pub cors_allowed_origins: Vec<String>,
     pub allow_registration: bool,
+    pub embedding_provider: EmbeddingProvider,
+    pub vector_provider: VectorProvider,
 }
 
 impl Default for Config {
@@ -21,6 +24,11 @@ impl Default for Config {
                 .to_string(),
             cors_allowed_origins: vec!["http://localhost:5173".to_string()],
             allow_registration: true,
+            embedding_provider: EmbeddingProvider::FastEmbed,
+            vector_provider: VectorProvider::Qdrant {
+                url: "http://localhost:6334".to_string(),
+                collection: "notes".to_string(),
+            },
         }
     }
 }
@@ -56,6 +64,19 @@ impl Config {
             .map(|s| s.to_lowercase() == "true")
             .unwrap_or(true);
 
+        let embedding_provider = match env::var("EMBEDDING_PROVIDER").unwrap_or_default().as_str() {
+            // Future: "ollama" => EmbeddingProvider::Ollama(...),
+            _ => EmbeddingProvider::FastEmbed,
+        };
+
+        let vector_provider = match env::var("VECTOR_PROVIDER").unwrap_or_default().as_str() {
+            // Future: "postgres" => ...
+            _ => VectorProvider::Qdrant {
+                url: env::var("QDRANT_URL").unwrap_or_else(|_| "http://localhost:6334".to_string()),
+                collection: env::var("QDRANT_COLLECTION").unwrap_or_else(|_| "notes".to_string()),
+            },
+        };
+
         Self {
             host,
             port,
@@ -63,6 +84,8 @@ impl Config {
             session_secret,
             cors_allowed_origins,
             allow_registration,
+            embedding_provider,
+            vector_provider,
         }
     }
 }

notes-api/src/error.rs

@@ -55,7 +55,9 @@ impl IntoResponse for ApiError {
 
                     DomainError::Unauthorized(_) => StatusCode::FORBIDDEN,
 
-                    DomainError::RepositoryError(_) => StatusCode::INTERNAL_SERVER_ERROR,
+                    DomainError::RepositoryError(_) | DomainError::InfrastructureError(_) => {
+                        StatusCode::INTERNAL_SERVER_ERROR
+                    }
                 };
 
                 (

notes-domain/src/entities.rs

@@ -204,6 +204,27 @@ impl NoteVersion {
     }
 }
 
+/// A derived link between two notes, typically generated by semantic similarity.
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub struct NoteLink {
+    pub source_note_id: Uuid,
+    pub target_note_id: Uuid,
+    /// Similarity score (0.0 to 1.0)
+    pub score: f32,
+    pub created_at: DateTime<Utc>,
+}
+
+impl NoteLink {
+    pub fn new(source_note_id: Uuid, target_note_id: Uuid, score: f32) -> Self {
+        Self {
+            source_note_id,
+            target_note_id,
+            score,
+            created_at: Utc::now(),
+        }
+    }
+}
+
 /// Filter options for querying notes
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct NoteFilter {

notes-domain/src/errors.rs

@@ -47,6 +47,10 @@ pub enum DomainError {
     /// A repository/infrastructure error occurred
     #[error("Repository error: {0}")]
     RepositoryError(String),
+
+    /// An infrastructure adapter error occurred
+    #[error("Infrastructure error: {0}")]
+    InfrastructureError(String),
 }
 
 impl DomainError {

notes-domain/src/lib.rs

@@ -10,6 +10,7 @@
 
 pub mod entities;
 pub mod errors;
+pub mod ports;
 pub mod repositories;
 pub mod services;
 

notes-domain/src/ports.rs

@@ -0,0 +1,33 @@
+use async_trait::async_trait;
+use uuid::Uuid;
+
+use crate::entities::NoteLink;
+use crate::errors::DomainResult;
+
+/// Defines how to generate vector embeddings from text.
+#[async_trait]
+pub trait EmbeddingGenerator: Send + Sync {
+    /// Generate a vector embedding for the given text.
+    async fn generate_embedding(&self, text: &str) -> DomainResult<Vec<f32>>;
+}
+
+/// Defines how to store and retrieve vectors.
+#[async_trait]
+pub trait VectorStore: Send + Sync {
+    /// Upsert a vector for a given note ID.
+    async fn upsert(&self, id: Uuid, vector: &[f32]) -> DomainResult<()>;
+
+    /// Find similar items to the given vector.
+    /// Returns a list of (NoteID, Score) tuples.
+    async fn find_similar(&self, vector: &[f32], limit: usize) -> DomainResult<Vec<(Uuid, f32)>>;
+}
+
+/// Defines how to persist note links.
+#[async_trait]
+pub trait LinkRepository: Send + Sync {
+    /// Save a batch of generated links.
+    async fn save_links(&self, links: &[NoteLink]) -> DomainResult<()>;
+
+    /// Delete existing links for a specific source note (e.g., before regenerating).
+    async fn delete_links_for_source(&self, source_note_id: Uuid) -> DomainResult<()>;
+}

notes-domain/src/services.rs

@@ -356,6 +356,58 @@ impl UserService {
     }
 }
 
+/// Service for Smart Features (Embeddings, Vector Search, Linking)
+pub struct SmartNoteService {
+    embedding_generator: Arc<dyn crate::ports::EmbeddingGenerator>,
+    vector_store: Arc<dyn crate::ports::VectorStore>,
+    link_repo: Arc<dyn crate::ports::LinkRepository>,
+}
+
+impl SmartNoteService {
+    pub fn new(
+        embedding_generator: Arc<dyn crate::ports::EmbeddingGenerator>,
+        vector_store: Arc<dyn crate::ports::VectorStore>,
+        link_repo: Arc<dyn crate::ports::LinkRepository>,
+    ) -> Self {
+        Self {
+            embedding_generator,
+            vector_store,
+            link_repo,
+        }
+    }
+
+    /// Process a note to generate embeddings and find similar notes
+    pub async fn process_note(&self, note: &Note) -> DomainResult<()> {
+        // 1. Generate embedding
+        let embedding = self
+            .embedding_generator
+            .generate_embedding(&note.content)
+            .await?;
+
+        // 2. Upsert to vector store
+        self.vector_store.upsert(note.id, &embedding).await?;
+
+        // 3. Find similar notes
+        // TODO: Make limit configurable
+        let similar = self.vector_store.find_similar(&embedding, 5).await?;
+
+        // 4. Create links
+        let links: Vec<crate::entities::NoteLink> = similar
+            .into_iter()
+            .filter(|(id, _)| *id != note.id) // Exclude self
+            .map(|(target_id, score)| crate::entities::NoteLink::new(note.id, target_id, score))
+            .collect();
+
+        // 5. Save links (replacing old ones)
+        if !links.is_empty() {
+            self.link_repo.delete_links_for_source(note.id).await?;
+            self.link_repo.save_links(&links).await?;
+        }
+
+        Ok(())
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

notes-infra/Cargo.toml

@@ -19,3 +19,6 @@ tracing = "0.1"
 uuid = { version = "1.19.0", features = ["v4", "serde"] }
 tower-sessions = "0.14.0"
 tower-sessions-sqlx-store = { version = "0.15.0", default-features = false }
+fastembed = "5.4"
+qdrant-client = "1.16"
+serde_json = "1.0"

notes-infra/src/embeddings/fastembed.rs

@@ -0,0 +1,48 @@
+use async_trait::async_trait;
+use fastembed::{EmbeddingModel, InitOptions, TextEmbedding};
+use notes_domain::errors::{DomainError, DomainResult};
+use notes_domain::ports::EmbeddingGenerator;
+use std::sync::{Arc, Mutex};
+
+pub struct FastEmbedAdapter {
+    model: Arc<Mutex<TextEmbedding>>,
+}
+
+impl FastEmbedAdapter {
+    pub fn new() -> DomainResult<Self> {
+        let mut options = InitOptions::default();
+        options.model_name = EmbeddingModel::AllMiniLML6V2;
+        options.show_download_progress = false;
+
+        let model = TextEmbedding::try_new(options).map_err(|e| {
+            DomainError::InfrastructureError(format!("Failed to init fastembed: {}", e))
+        })?;
+
+        Ok(Self {
+            model: Arc::new(Mutex::new(model)),
+        })
+    }
+}
+
+#[async_trait]
+impl EmbeddingGenerator for FastEmbedAdapter {
+    async fn generate_embedding(&self, text: &str) -> DomainResult<Vec<f32>> {
+        let model = self.model.clone();
+        let text = text.to_string();
+
+        let embeddings = tokio::task::spawn_blocking(move || {
+            let mut model = model.lock().map_err(|e| format!("Lock error: {}", e))?;
+            model
+                .embed(vec![text], None)
+                .map_err(|e| format!("Embed error: {}", e))
+        })
+        .await
+        .map_err(|e| DomainError::InfrastructureError(format!("Join error: {}", e)))?
+        .map_err(|e| DomainError::InfrastructureError(e))?;
+
+        embeddings
+            .into_iter()
+            .next()
+            .ok_or_else(|| DomainError::InfrastructureError("No embedding generated".to_string()))
+    }
+}

notes-infra/src/embeddings/mod.rs

@@ -0,0 +1 @@
+pub mod fastembed;

notes-infra/src/factory.rs

@@ -11,10 +11,61 @@ pub enum FactoryError {
     Database(#[from] sqlx::Error),
     #[error("Not implemented: {0}")]
     NotImplemented(String),
+    #[error("Infrastructure error: {0}")]
+    Infrastructure(#[from] notes_domain::DomainError),
 }
 
 pub type FactoryResult<T> = Result<T, FactoryError>;
 
+#[derive(Debug, Clone)]
+pub enum EmbeddingProvider {
+    FastEmbed,
+    // Ollama(String), // Url
+    // OpenAI(String), // ApiKey
+}
+
+#[derive(Debug, Clone)]
+pub enum VectorProvider {
+    Qdrant { url: String, collection: String },
+    // InMemory,
+}
+
+pub async fn build_embedding_generator(
+    provider: &EmbeddingProvider,
+) -> FactoryResult<Arc<dyn notes_domain::ports::EmbeddingGenerator>> {
+    match provider {
+        EmbeddingProvider::FastEmbed => {
+            let adapter = crate::embeddings::fastembed::FastEmbedAdapter::new()?;
+            Ok(Arc::new(adapter))
+        }
+    }
+}
+
+pub async fn build_vector_store(
+    provider: &VectorProvider,
+) -> FactoryResult<Arc<dyn notes_domain::ports::VectorStore>> {
+    match provider {
+        VectorProvider::Qdrant { url, collection } => {
+            let adapter = crate::vector::qdrant::QdrantVectorAdapter::new(url, collection)?;
+            Ok(Arc::new(adapter))
+        }
+    }
+}
+
+#[cfg(feature = "sqlite")]
+pub async fn build_link_repository(
+    pool: &DatabasePool,
+) -> FactoryResult<Arc<dyn notes_domain::ports::LinkRepository>> {
+    match pool {
+        DatabasePool::Sqlite(pool) => Ok(Arc::new(
+            crate::link_repository::SqliteLinkRepository::new(pool.clone()),
+        )),
+        _ => Err(FactoryError::NotImplemented(
+            "LinkRepostiory for non-sqlite".to_string(),
+        )),
+    }
+}
+
 pub async fn build_database_pool(db_config: &DatabaseConfig) -> FactoryResult<DatabasePool> {
     if db_config.url.starts_with("sqlite:") {
         #[cfg(feature = "sqlite")]

notes-infra/src/lib.rs

@@ -15,20 +15,26 @@
 //! - [`db::run_migrations`] - Run database migrations
 
 pub mod db;
+pub mod embeddings;
 pub mod factory;
 #[cfg(feature = "sqlite")]
+pub mod link_repository;
+#[cfg(feature = "sqlite")]
 pub mod note_repository;
 pub mod session_store;
 #[cfg(feature = "sqlite")]
 pub mod tag_repository;
 #[cfg(feature = "sqlite")]
 pub mod user_repository;
+pub mod vector;
 
 // Re-export for convenience
 #[cfg(feature = "sqlite")]
 pub use db::create_pool;
 pub use db::{DatabaseConfig, run_migrations};
 #[cfg(feature = "sqlite")]
+pub use link_repository::SqliteLinkRepository;
+#[cfg(feature = "sqlite")]
 pub use note_repository::SqliteNoteRepository;
 #[cfg(feature = "sqlite")]
 pub use tag_repository::SqliteTagRepository;

notes-infra/src/link_repository.rs

@@ -0,0 +1,68 @@
+use async_trait::async_trait;
+use sqlx::SqlitePool;
+use uuid::Uuid;
+
+use notes_domain::entities::NoteLink;
+use notes_domain::errors::{DomainError, DomainResult};
+use notes_domain::ports::LinkRepository;
+
+pub struct SqliteLinkRepository {
+    pool: SqlitePool,
+}
+
+impl SqliteLinkRepository {
+    pub fn new(pool: SqlitePool) -> Self {
+        Self { pool }
+    }
+}
+
+#[async_trait]
+impl LinkRepository for SqliteLinkRepository {
+    async fn save_links(&self, links: &[NoteLink]) -> DomainResult<()> {
+        let mut tx = self
+            .pool
+            .begin()
+            .await
+            .map_err(|e| DomainError::RepositoryError(e.to_string()))?;
+
+        for link in links {
+            let source = link.source_note_id.to_string();
+            let target = link.target_note_id.to_string();
+            let created_at = link.created_at.to_rfc3339();
+
+            sqlx::query(
+                r#"
+                INSERT INTO note_links (source_note_id, target_note_id, score, created_at)
+                VALUES (?, ?, ?, ?)
+                ON CONFLICT(source_note_id, target_note_id) DO UPDATE SET
+                    score = excluded.score,
+                    created_at = excluded.created_at
+                "#,
+            )
+            .bind(source)
+            .bind(target)
+            .bind(link.score)
+            .bind(created_at)
+            .execute(&mut *tx)
+            .await
+            .map_err(|e| DomainError::RepositoryError(e.to_string()))?;
+        }
+
+        tx.commit()
+            .await
+            .map_err(|e| DomainError::RepositoryError(e.to_string()))?;
+
+        Ok(())
+    }
+
+    async fn delete_links_for_source(&self, source_note_id: Uuid) -> DomainResult<()> {
+        let source_str = source_note_id.to_string();
+        sqlx::query("DELETE FROM note_links WHERE source_note_id = ?")
+            .bind(source_str)
+            .execute(&self.pool)
+            .await
+            .map_err(|e| DomainError::RepositoryError(e.to_string()))?;
+
+        Ok(())
+    }
+}

notes-infra/src/vector/mod.rs

@@ -0,0 +1 @@
+pub mod qdrant;

notes-infra/src/vector/qdrant.rs

@@ -0,0 +1,73 @@
+use async_trait::async_trait;
+use notes_domain::errors::{DomainError, DomainResult};
+use notes_domain::ports::VectorStore;
+use qdrant_client::Qdrant;
+use qdrant_client::qdrant::{PointStruct, SearchPointsBuilder, UpsertPointsBuilder, Value};
+use std::collections::HashMap;
+use std::sync::Arc;
+use uuid::Uuid;
+
+pub struct QdrantVectorAdapter {
+    client: Arc<Qdrant>,
+    collection_name: String,
+}
+
+impl QdrantVectorAdapter {
+    pub fn new(url: &str, collection_name: &str) -> DomainResult<Self> {
+        let client = Qdrant::from_url(url).build().map_err(|e| {
+            DomainError::InfrastructureError(format!("Failed to create Qdrant client: {}", e))
+        })?;
+
+        Ok(Self {
+            client: Arc::new(client),
+            collection_name: collection_name.to_string(),
+        })
+    }
+}
+
+#[async_trait]
+impl VectorStore for QdrantVectorAdapter {
+    async fn upsert(&self, id: Uuid, vector: &[f32]) -> DomainResult<()> {
+        let payload: HashMap<String, Value> = HashMap::new();
+
+        let point = PointStruct::new(id.to_string(), vector.to_vec(), payload);
+
+        let upsert_points = UpsertPointsBuilder::new(self.collection_name.clone(), vec![point]);
+
+        self.client
+            .upsert_points(upsert_points)
+            .await
+            .map_err(|e| DomainError::InfrastructureError(format!("Qdrant upsert error: {}", e)))?;
+
+        Ok(())
+    }
+
+    async fn find_similar(&self, vector: &[f32], limit: usize) -> DomainResult<Vec<(Uuid, f32)>> {
+        let search_points =
+            SearchPointsBuilder::new(self.collection_name.clone(), vector.to_vec(), limit as u64)
+                .with_payload(true);
+
+        let search_result = self
+            .client
+            .search_points(search_points)
+            .await
+            .map_err(|e| DomainError::InfrastructureError(format!("Qdrant search error: {}", e)))?;
+
+        let results = search_result
+            .result
+            .into_iter()
+            .filter_map(|point| {
+                let id = point.id?;
+                let uuid_str = match id.point_id_options? {
+                    qdrant_client::qdrant::point_id::PointIdOptions::Uuid(u) => u,
+                    _ => return None,
+                };
+
+                let uuid = Uuid::parse_str(&uuid_str).ok()?;
+                Some((uuid, point.score))
+            })
+            .collect();
+
+        Ok(results)
+    }
+}

notes-worker/src/config.rs

@@ -1,7 +1,11 @@
+use notes_infra::factory::{EmbeddingProvider, VectorProvider};
+
 #[derive(Debug, Clone)]
 pub struct Config {
     pub broker_url: String,
     pub database_url: String,
+    pub embedding_provider: EmbeddingProvider,
+    pub vector_provider: VectorProvider,
 }
 
 impl Default for Config {
@@ -9,6 +13,11 @@ impl Default for Config {
         Self {
             broker_url: "nats://localhost:4222".to_string(),
             database_url: "sqlite::memory:".to_string(),
+            embedding_provider: EmbeddingProvider::FastEmbed,
+            vector_provider: VectorProvider::Qdrant {
+                url: "http://localhost:6334".to_string(),
+                collection: "notes".to_string(),
+            },
         }
     }
 }
@@ -17,9 +26,30 @@ impl Config {
     pub fn from_env() -> Self {
         let _ = dotenvy::dotenv();
 
+        let embedding_provider = match std::env::var("EMBEDDING_PROVIDER")
+            .unwrap_or_default()
+            .as_str()
+        {
+            _ => EmbeddingProvider::FastEmbed,
+        };
+
+        let vector_provider = match std::env::var("VECTOR_PROVIDER")
+            .unwrap_or_default()
+            .as_str()
+        {
+            _ => VectorProvider::Qdrant {
+                url: std::env::var("QDRANT_URL")
+                    .unwrap_or_else(|_| "http://localhost:6334".to_string()),
+                collection: std::env::var("QDRANT_COLLECTION")
+                    .unwrap_or_else(|_| "notes".to_string()),
+            },
+        };
+
         Self {
             broker_url: std::env::var("BROKER_URL").unwrap_or("nats://localhost:4222".to_string()),
             database_url: std::env::var("DATABASE_URL").unwrap_or("sqlite::memory:".to_string()),
+            embedding_provider,
+            vector_provider,
         }
     }
 }

notes-worker/src/main.rs

@@ -1,4 +1,10 @@
-use notes_infra::{DatabaseConfig, create_pool};
+use notes_domain::services::SmartNoteService;
+use notes_infra::{
+    DatabaseConfig,
+    factory::{
+        build_database_pool, build_embedding_generator, build_link_repository, build_vector_store,
+    },
+};
 
 use crate::config::Config;
 
@@ -7,10 +13,24 @@ mod config;
 #[tokio::main]
 async fn main() -> anyhow::Result<()> {
     let config = Config::from_env();
-    let nats_client = async_nats::connect(config.broker_url).await?;
-    let db_config = DatabaseConfig::new(config.database_url);
-    let db_pool = create_pool(&db_config).await?;
+    let nats_client = async_nats::connect(&config.broker_url).await?;
+    let db_config = DatabaseConfig::new(config.database_url.clone());
+    let db_pool = build_database_pool(&db_config).await?;
+
+    // Initialize smart feature adapters
+    let embedding_generator = build_embedding_generator(&config.embedding_provider).await?;
+    let vector_store = build_vector_store(&config.vector_provider).await?;
+    let link_repo = build_link_repository(&db_pool).await?;
+
+    // Create the service
+    let smart_service = SmartNoteService::new(embedding_generator, vector_store, link_repo);
+    tracing::info!(
+        "SmartNoteService initialized successfully with {:?}",
+        config.embedding_provider
+    );
 
     // subscribe to jobs and process them
+    // (Future: consume NATS messages and call smart_service.process_note(&note))
+
     Ok(())
 }