chore: harden common storage bootstrap and slim embedded db assets

Unify embedding config, build providers from system settings, and fail
startup when index builds error or time out. Move Surreal assets under
common/db so embeds exclude crate source, and read storage via streams.

common/src/utils/embedding.rs

@@ -8,59 +8,15 @@ use std::{
 use anyhow::{anyhow, Context, Result};
 use async_openai::{types::CreateEmbeddingRequestArgs, Client};
 use fastembed::{EmbeddingModel, ModelTrait, TextEmbedding, TextInitOptions};
-use serde::{Deserialize, Serialize};
-use thiserror::Error;
 use tracing::debug;
 
 use crate::{
     error::AppError,
     storage::{db::SurrealDbClient, types::system_settings::SystemSettings},
+    utils::config::AppConfig,
 };
 
-/// Error returned when parsing an embedding backend name.
-#[derive(Debug, Error, PartialEq, Eq)]
-#[error("unknown embedding backend '{input}': expected 'openai', 'hashed', or 'fastembed'")]
-pub struct ParseEmbeddingBackendError {
-    /// The unrecognized input string.
-    pub input: String,
-}
-
-/// Supported embedding backends.
-#[allow(clippy::module_name_repetitions)]
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Serialize, Deserialize)]
-#[serde(rename_all = "lowercase")]
-pub enum EmbeddingBackend {
-    #[default]
-    OpenAI,
-    FastEmbed,
-    Hashed,
-}
-
-impl EmbeddingBackend {
-    #[must_use]
-    pub fn as_str(self) -> &'static str {
-        match self {
-            Self::OpenAI => "openai",
-            Self::FastEmbed => "fastembed",
-            Self::Hashed => "hashed",
-        }
-    }
-}
-
-impl std::str::FromStr for EmbeddingBackend {
-    type Err = ParseEmbeddingBackendError;
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        match s.to_ascii_lowercase().as_str() {
-            "openai" => Ok(Self::OpenAI),
-            "hashed" => Ok(Self::Hashed),
-            "fastembed" | "fast-embed" | "fast" => Ok(Self::FastEmbed),
-            other => Err(ParseEmbeddingBackendError {
-                input: other.to_string(),
-            }),
-        }
-    }
-}
+pub use crate::utils::config::{EmbeddingBackend, ParseEmbeddingBackendError};
 
 /// Wrapper around the chosen embedding backend.
 #[allow(clippy::module_name_repetitions)]
@@ -281,30 +237,31 @@ impl EmbeddingProvider {
         })
     }
 
-    /// Creates an embedding provider based on application configuration.
+    /// Creates an embedding provider from persisted settings and bootstrap config.
     ///
-    /// Dispatches to the appropriate constructor based on `config.embedding_backend`:
-    /// - `OpenAI`: Requires a valid OpenAI client
-    /// - `FastEmbed`: Uses local embedding model
-    /// - `Hashed`: Uses deterministic hashed embeddings (for testing)
-    pub async fn from_config(
-        config: &crate::utils::config::AppConfig,
+    /// Model name and dimensions come from [`SystemSettings`]. The active backend is taken
+    /// from `config.embedding_backend` at startup; [`SystemSettings::sync_from_embedding_provider`]
+    /// persists the resolved backend to the database.
+    pub async fn from_system_settings(
+        settings: &SystemSettings,
+        config: &AppConfig,
         openai_client: Option<Arc<Client<async_openai::config::OpenAIConfig>>>,
     ) -> Result<Self> {
-        use crate::utils::config::EmbeddingBackend;
-
+        let dimensions = settings.embedding_dimensions;
         match config.embedding_backend {
             EmbeddingBackend::OpenAI => {
                 let client = openai_client
                     .ok_or_else(|| anyhow!("OpenAI embedding backend requires an OpenAI client"))?;
-                // Use defaults that match SystemSettings initial values
-                Self::new_openai(client, "text-embedding-3-small".to_string(), 1536)
+                Self::new_openai(client, settings.embedding_model.clone(), dimensions)
             }
             EmbeddingBackend::FastEmbed => {
-                // Use nomic-embed-text-v1.5 as the default FastEmbed model
-                Self::new_fastembed(Some("nomic-ai/nomic-embed-text-v1.5".to_string())).await
+                Self::new_fastembed(Some(settings.embedding_model.clone())).await
+            }
+            EmbeddingBackend::Hashed => {
+                let dimension = usize::try_from(dimensions)
+                    .map_err(|_| anyhow!("embedding_dimensions exceeds usize::MAX"))?;
+                Self::new_hashed(dimension)
             }
-            EmbeddingBackend::Hashed => Self::new_hashed(384),
         }
     }
 }
@@ -460,6 +417,14 @@ mod tests {
     use crate::storage::types::system_settings::SystemSettings;
     use serde_json::json;
 
+    #[test]
+    fn embedding_backend_defaults_to_fastembed() {
+        assert_eq!(
+            EmbeddingBackend::default(),
+            EmbeddingBackend::FastEmbed
+        );
+    }
+
     #[test]
     fn embedding_backend_as_str_matches_serde_names() {
         assert_eq!(EmbeddingBackend::OpenAI.as_str(), "openai");