WIP 5 add image embedding provider (local only for now)

src/cmd.rs

@@ -1325,6 +1325,7 @@ impl Cmd {
                 let p_lc = provider.to_lowercase();
                 let prov = match p_lc.as_str() {
                     "test-hash" | "testhash" => EmbeddingProvider::TestHash,
+                    "testimagehash" | "image-test-hash" | "imagetesthash" => EmbeddingProvider::ImageTestHash,
                     "fastembed" | "lancefastembed" => EmbeddingProvider::LanceFastEmbed,
                     "openai" | "lanceopenai" => EmbeddingProvider::LanceOpenAI,
                     other => EmbeddingProvider::LanceOther(other.to_string()),
@@ -1346,6 +1347,7 @@ impl Cmd {
                         arr.push(Protocol::BulkString("provider".to_string()));
                         arr.push(Protocol::BulkString(match cfg.provider {
                             EmbeddingProvider::TestHash => "test-hash".to_string(),
+                            EmbeddingProvider::ImageTestHash => "testimagehash".to_string(),
                             EmbeddingProvider::LanceFastEmbed => "lancefastembed".to_string(),
                             EmbeddingProvider::LanceOpenAI => "lanceopenai".to_string(),
                             EmbeddingProvider::LanceOther(ref s) => s.clone(),

src/embedding.rs

@@ -30,8 +30,10 @@ use serde_json::json;
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
 #[serde(rename_all = "snake_case")]
 pub enum EmbeddingProvider {
-    // Deterministic, local-only embedder for CI and offline development.
+    // Deterministic, local-only embedder for CI and offline development (text).
     TestHash,
+    // Deterministic, local-only embedder for CI and offline development (image).
+    ImageTestHash,
     // Placeholders for LanceDB-supported providers; implementers can add concrete backends later.
     LanceFastEmbed,
     LanceOpenAI,
@@ -71,6 +73,8 @@ pub trait Embedder: Send + Sync {
     }
 }
 
+//// ----------------------------- TEXT: deterministic test embedder -----------------------------
+
 /// Deterministic, no-deps, no-network embedder for CI and offline dev.
 /// Algorithm:
 /// - Fold bytes of UTF-8 into 'dim' buckets with a simple rolling hash
@@ -127,6 +131,77 @@ impl Embedder for TestHashEmbedder {
     }
 }
 
+//// ----------------------------- IMAGE: trait + deterministic test embedder -----------------------------
+
+/// Image embedding interface (separate from text to keep modality-specific inputs).
+pub trait ImageEmbedder: Send + Sync {
+    /// Human-readable provider/model name
+    fn name(&self) -> String;
+    /// Embedding dimension
+    fn dim(&self) -> usize;
+    /// Embed a single image (raw bytes)
+    fn embed_image(&self, bytes: &[u8]) -> Result<Vec<f32>, DBError>;
+    /// Embed many images; default maps embed_image() over inputs
+    fn embed_many_images(&self, images: &[Vec<u8>]) -> Result<Vec<Vec<f32>>, DBError> {
+        images.iter().map(|b| self.embed_image(b)).collect()
+    }
+}
+
+/// Deterministic image embedder that folds bytes into buckets, applies tanh-like nonlinearity,
+/// and L2-normalizes. Suitable for CI and offline development.
+/// NOTE: This is NOT semantic; it is a stable hash-like representation.
+pub struct TestImageHashEmbedder {
+    dim: usize,
+    model_name: String,
+}
+
+impl TestImageHashEmbedder {
+    pub fn new(dim: usize, model_name: impl Into<String>) -> Self {
+        Self { dim, model_name: model_name.into() }
+    }
+
+    fn l2_normalize(mut v: Vec<f32>) -> Vec<f32> {
+        let norm: f32 = v.iter().map(|x| x * x).sum::<f32>().sqrt();
+        if norm > 0.0 {
+            for x in &mut v {
+                *x /= norm;
+            }
+        }
+        v
+    }
+}
+
+impl ImageEmbedder for TestImageHashEmbedder {
+    fn name(&self) -> String {
+        format!("test-image-hash:{}", self.model_name)
+    }
+
+    fn dim(&self) -> usize {
+        self.dim
+    }
+
+    fn embed_image(&self, bytes: &[u8]) -> Result<Vec<f32>, DBError> {
+        // Deterministic fold across bytes with two rolling accumulators.
+        let mut acc = vec![0f32; self.dim];
+        let mut h1: u32 = 0x811C9DC5; // FNV-like
+        let mut h2: u32 = 0x9E3779B9; // golden ratio
+        for (i, b) in bytes.iter().enumerate() {
+            h1 ^= *b as u32;
+            h1 = h1.wrapping_mul(16777619u32);
+            // combine with position and h2
+            h2 = h2.wrapping_add(((i as u32).rotate_left((i % 13) as u32)) ^ h1.rotate_left((i % 7) as u32));
+            let idx = (h1 ^ h2) as usize % self.dim;
+            // Map to [-1,1] and decay with position
+            let val = ((*b as f32) / 127.5 - 1.0) * (1.0 / (1.0 + (i as f32 / 128.0)));
+            acc[idx] += val;
+        }
+        for x in &mut acc {
+            *x = x.tanh();
+        }
+        Ok(Self::l2_normalize(acc))
+    }
+}
+
 //// OpenAI embedder (supports OpenAI and Azure OpenAI via REST)
 struct OpenAIEmbedder {
     model: String,
@@ -320,7 +395,25 @@ pub fn create_embedder(config: &EmbeddingConfig) -> Result<Arc<dyn Embedder>, DB
             let inner = OpenAIEmbedder::new_from_config(config)?;
             Ok(Arc::new(inner))
         }
+        EmbeddingProvider::ImageTestHash => {
+            Err(DBError("Use create_image_embedder() for image providers".into()))
+        }
         EmbeddingProvider::LanceFastEmbed => Err(DBError("LanceFastEmbed provider not yet implemented in Rust embedding layer; configure 'test-hash' or use 'openai'".into())),
         EmbeddingProvider::LanceOther(p) => Err(DBError(format!("Lance provider '{}' not implemented; configure 'openai' or 'test-hash'", p))),
     }
+}
+
+/// Create an image embedder instance from a config.
+pub fn create_image_embedder(config: &EmbeddingConfig) -> Result<Arc<dyn ImageEmbedder>, DBError> {
+    match &config.provider {
+        EmbeddingProvider::ImageTestHash => {
+            let dim = config.get_param_usize("dim").unwrap_or(512);
+            Ok(Arc::new(TestImageHashEmbedder::new(dim, config.model.clone())))
+        }
+        EmbeddingProvider::TestHash | EmbeddingProvider::LanceOpenAI => {
+            Err(DBError("Configured text provider; dataset expects image provider (e.g., 'testimagehash')".into()))
+        }
+        EmbeddingProvider::LanceFastEmbed => Err(DBError("Image provider 'lancefastembed' not yet implemented".into())),
+        EmbeddingProvider::LanceOther(p) => Err(DBError(format!("Image provider '{}' not implemented; use 'testimagehash' for now", p))),
+    }
 }

src/rpc.rs

@@ -996,6 +996,7 @@ impl RpcServer for RpcServerImpl {
         }
         let prov = match provider.to_lowercase().as_str() {
             "test-hash" | "testhash" => EmbeddingProvider::TestHash,
+            "testimagehash" | "image-test-hash" | "imagetesthash" => EmbeddingProvider::ImageTestHash,
             "fastembed" | "lancefastembed" => EmbeddingProvider::LanceFastEmbed,
             "openai" | "lanceopenai" => EmbeddingProvider::LanceOpenAI,
             other => EmbeddingProvider::LanceOther(other.to_string()),
@@ -1030,6 +1031,7 @@ impl RpcServer for RpcServerImpl {
         Ok(serde_json::json!({
             "provider": match cfg.provider {
                 EmbeddingProvider::TestHash => "test-hash",
+                EmbeddingProvider::ImageTestHash => "testimagehash",
                 EmbeddingProvider::LanceFastEmbed => "lancefastembed",
                 EmbeddingProvider::LanceOpenAI => "lanceopenai",
                 EmbeddingProvider::LanceOther(ref s) => s,