updated RAG Search functionality

README.md

@@ -45,6 +45,9 @@ BACKEND_UPLOAD_DIR=uploads
 WHISPER_MODEL=base
 WHISPER_DEVICE=cpu
 WHISPER_COMPUTE_TYPE=int8
+EMBEDDING_PROVIDER=local
+OPENAI_EMBEDDING_MODEL=text-embedding-3-small
+# OPENAI_API_KEY=...   # only needed if EMBEDDING_PROVIDER=openai
 ```
 
 Notes:

backend/api_routes.py

@@ -7,6 +7,8 @@ import hashlib
 import json
 import os
 import uuid
+import math
+import re
 from pathlib import Path
 import io
 import zipfile
@@ -38,6 +40,7 @@ from db_queries import (
     list_rag_chunks,
     list_user_history,
     search_rag_chunks,
+    search_rag_chunks_vector,
     update_audio_post,
     upload_storage_object,
     upsert_archive_metadata,
@@ -61,6 +64,10 @@ WHISPER_COMPUTE_TYPE = os.getenv("WHISPER_COMPUTE_TYPE", "int8")
 ARCHIVE_BUCKET = os.getenv("SUPABASE_BUCKET", os.getenv("SUPABASE_ARCHIVE_BUCKET", "archives"))
 
 _whisper_model: WhisperModel | None = None
+_openai_client = None
+EMBEDDING_DIM = 1536
+EMBEDDING_PROVIDER = (os.getenv("EMBEDDING_PROVIDER") or "local").strip().lower()
+OPENAI_EMBEDDING_MODEL = (os.getenv("OPENAI_EMBEDDING_MODEL") or "text-embedding-3-small").strip()
 
 
 def _model() -> WhisperModel:
@@ -103,6 +110,62 @@ def _build_prompt(transcript_text: str, title: str) -> str:
         f"{transcript_text}\n\n"
         "Answer user questions grounded in this transcript."
     )
+
+
+def _local_embedding(text: str, dim: int = EMBEDDING_DIM) -> list[float]:
+    """
+    Free fallback embedding: hashed bag-of-words + bi-grams, L2-normalized.
+    This is weaker than model embeddings but keeps vector search functional.
+    """
+    if not text:
+        return [0.0] * dim
+
+    vec = [0.0] * dim
+    tokens = re.findall(r"[a-z0-9]+", text.lower())
+    if not tokens:
+        return vec
+
+    for i, tok in enumerate(tokens):
+        idx = int(hashlib.sha256(f"u:{tok}".encode("utf-8")).hexdigest(), 16) % dim
+        vec[idx] += 1.0
+        if i < len(tokens) - 1:
+            bigram = f"{tok}_{tokens[i+1]}"
+            bidx = int(hashlib.sha256(f"b:{bigram}".encode("utf-8")).hexdigest(), 16) % dim
+            vec[bidx] += 0.5
+
+    norm = math.sqrt(sum(v * v for v in vec))
+    if norm > 0:
+        vec = [v / norm for v in vec]
+    return vec
+
+
+def _openai_embedding(text: str) -> list[float] | None:
+    global _openai_client
+    api_key = (os.getenv("OPENAI_API_KEY") or "").strip()
+    if not api_key:
+        return None
+
+    try:
+        if _openai_client is None:
+            from openai import OpenAI
+            _openai_client = OpenAI(api_key=api_key)
+        response = _openai_client.embeddings.create(
+            model=OPENAI_EMBEDDING_MODEL,
+            input=text,
+        )
+        return response.data[0].embedding
+    except Exception:
+        return None
+
+
+def _embed_text(text: str) -> list[float]:
+    if EMBEDDING_PROVIDER == "openai":
+        emb = _openai_embedding(text)
+        if emb:
+            return emb
+    return _local_embedding(text)
+
+
 def _add_audio_url(post: Dict[str, Any]) -> Dict[str, Any]:
     """Add signed audio URL to post if ready"""
     if post.get("status") == "ready":
@@ -281,7 +344,7 @@ def api_upload_post():
                     "end_sec": float(seg.end),
                     "text": segment_text,
                     "confidence": float(seg.avg_logprob) if seg.avg_logprob is not None else None,
-                    "embedding": None,
+                    "embedding": _embed_text(segment_text),
                 }
             )
 
@@ -376,8 +439,21 @@ def api_rag_search():
         return _error("'q' is required.", 400)
 
     try:
+        query_embedding = _embed_text(query_text)
+        rows = search_rag_chunks_vector(user_id=user_id, query_embedding=query_embedding, limit=limit)
+
+        # Fallback in case vector path is unavailable or empty.
+        mode = "vector"
+        if not rows:
             rows = search_rag_chunks(user_id=user_id, query_text=query_text, page=page, limit=limit)
-        return jsonify({"results": rows, "page": page, "limit": min(max(1, limit), 100)})
+            mode = "text_fallback"
+
+        return jsonify({
+            "results": rows,
+            "page": page,
+            "limit": min(max(1, limit), 100),
+            "mode": mode
+        })
     except Exception as e:
         return _error(str(e), 500)
 

backend/db_queries.py

@@ -3,6 +3,8 @@ Supabase data layer aligned with TitanForge/schema.sql.
 """
 
 import os
+import math
+import json
 from typing import Any, Dict, List, Optional, Tuple
 
 from dotenv import load_dotenv
@@ -399,15 +401,104 @@ def search_rag_chunks_vector(user_id: int, query_embedding: List[float], limit:
     Vector search via SQL RPC function `match_rag_chunks` (pgvector).
     """
     vector_text = "[" + ",".join(str(float(v)) for v in query_embedding) + "]"
+    safe_limit = min(max(1, limit), 100)
+
+    try:
         response = supabase.rpc(
             "match_rag_chunks",
             {
                 "p_user_id": user_id,
                 "p_query_embedding": vector_text,
-            "p_match_count": min(max(1, limit), 100),
+                "p_match_count": safe_limit,
             },
         ).execute()
-    return _rows(response)
+        rows = _rows(response)
+        if rows:
+            return rows
+    except Exception:
+        pass
+
+    # Fallback: pull candidate chunks and rank with cosine similarity in Python.
+    response = (
+        supabase.table("rag_chunks")
+        .select(
+            "chunk_id, post_id, start_sec, end_sec, text, confidence, created_at, embedding, "
+            "audio_posts!inner(post_id, user_id, title, visibility, created_at)"
+        )
+        .eq("audio_posts.user_id", user_id)
+        .limit(3000)
+        .execute()
+    )
+    candidates = _rows(response)
+    if not candidates:
+        return []
+
+    q = _normalize_vec(query_embedding)
+    ranked = []
+    for row in candidates:
+        emb = _parse_embedding(row.get("embedding"))
+        if not emb:
+            continue
+        score = _cosine_similarity(q, emb)
+        if score is None:
+            continue
+        out = dict(row)
+        out["similarity"] = score
+        out.pop("embedding", None)
+        ranked.append(out)
+
+    ranked.sort(key=lambda r: r.get("similarity", 0.0), reverse=True)
+    return ranked[:safe_limit]
+
+
+def _parse_embedding(value: Any) -> Optional[List[float]]:
+    if value is None:
+        return None
+    if isinstance(value, list):
+        try:
+            return [float(v) for v in value]
+        except Exception:
+            return None
+    if isinstance(value, str):
+        text = value.strip()
+        if not text:
+            return None
+        try:
+            if text.startswith("[") and text.endswith("]"):
+                return [float(v) for v in text[1:-1].split(",") if v.strip()]
+            parsed = json.loads(text)
+            if isinstance(parsed, list):
+                return [float(v) for v in parsed]
+        except Exception:
+            return None
+    return None
+
+
+def _normalize_vec(vec: List[float]) -> List[float]:
+    if not vec:
+        return []
+    norm = math.sqrt(sum(float(v) * float(v) for v in vec))
+    if norm <= 0:
+        return [0.0 for _ in vec]
+    return [float(v) / norm for v in vec]
+
+
+def _cosine_similarity(a: List[float], b: List[float]) -> Optional[float]:
+    if not a or not b:
+        return None
+    n = min(len(a), len(b))
+    if n == 0:
+        return None
+    dot = 0.0
+    bnorm = 0.0
+    for i in range(n):
+        av = float(a[i])
+        bv = float(b[i])
+        dot += av * bv
+        bnorm += bv * bv
+    if bnorm <= 0:
+        return None
+    return dot / math.sqrt(bnorm)
 
 
 # ==================== Audit Log ====================