Fix: Prevent duplicate PDF processing when using --file-types .pdf

Fixes #175

Problem:
When --file-types .pdf is specified, PDFs were being processed twice:
1. Separately with PyMuPDF/pdfplumber extractors
2. Again in the 'other file types' section via SimpleDirectoryReader

This caused duplicate processing and potential conflicts.

Solution:
- Exclude .pdf from other_file_extensions when PDFs are already
  processed separately
- Only load other file types if there are extensions to process
- Prevents duplicate PDF processing

Changes:
- Added logic to filter out .pdf from code_extensions when loading
  other file types if PDFs were processed separately
- Updated SimpleDirectoryReader to use filtered extensions
- Added check to skip loading if no other extensions to process

.github/workflows/link-check.yml

@@ -14,6 +14,6 @@ jobs:
       - uses: actions/checkout@v4
       - uses: lycheeverse/lychee-action@v2
         with:
-          args: --no-progress --insecure --user-agent 'curl/7.68.0' README.md docs/ apps/ examples/ benchmarks/
+          args: --no-progress --insecure --user-agent 'curl/7.68.0' --exclude '.*api\.star-history\.com.*' --accept 200,201,202,203,204,205,206,207,208,226,300,301,302,303,304,305,306,307,308,503 README.md docs/ apps/ examples/ benchmarks/
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

README.md

@@ -16,12 +16,24 @@
   </a>
 </p>
 
+<div align="center">
+  <a href="https://forms.gle/rDbZf864gMNxhpTq8">
+    <img src="https://img.shields.io/badge/📣_Community_Survey-Help_Shape_v0.4-007ec6?style=for-the-badge&logo=google-forms&logoColor=white" alt="Take Survey">
+  </a>
+  <p>
+    We track <b>zero telemetry</b>. This survey is the ONLY way to tell us if you want <br>
+    <b>GPU Acceleration</b> or <b>More Integrations</b> next.<br>
+    👉 <a href="https://forms.gle/rDbZf864gMNxhpTq8"><b>Click here to cast your vote (2 mins)</b></a>
+  </p>
+</div>
+
 <h2 align="center" tabindex="-1" class="heading-element" dir="auto">
     The smallest vector index in the world. RAG Everything with LEANN!
 </h2>
 
 LEANN is an innovative vector database that democratizes personal AI. Transform your laptop into a powerful RAG system that can index and search through millions of documents while using **97% less storage** than traditional solutions **without accuracy loss**.
 
+
 LEANN achieves this through *graph-based selective recomputation* with *high-degree preserving pruning*, computing embeddings on-demand instead of storing them all. [Illustration Fig →](#️-architecture--how-it-works) | [Paper →](https://arxiv.org/abs/2506.08276)
 
 **Ready to RAG Everything?** Transform your laptop into a personal AI assistant that can semantic search your **[file system](#-personal-data-manager-process-any-documents-pdf-txt-md)**, **[emails](#-your-personal-email-secretary-rag-on-apple-mail)**, **[browser history](#-time-machine-for-the-web-rag-your-entire-browser-history)**, **[chat history](#-wechat-detective-unlock-your-golden-memories)** ([WeChat](#-wechat-detective-unlock-your-golden-memories), [iMessage](#-imessage-history-your-personal-conversation-archive)), **[agent memory](#-chatgpt-chat-history-your-personal-ai-conversation-archive)** ([ChatGPT](#-chatgpt-chat-history-your-personal-ai-conversation-archive), [Claude](#-claude-chat-history-your-personal-ai-conversation-archive)), **[live data](#mcp-integration-rag-on-live-data-from-any-platform)** ([Slack](#mcp-integration-rag-on-live-data-from-any-platform), [Twitter](#mcp-integration-rag-on-live-data-from-any-platform)), **[codebase](#-claude-code-integration-transform-your-development-workflow)**\* , or external knowledge bases (i.e., 60M documents) - all on your laptop, with zero cloud costs and complete privacy.

apps/slack_data/slack_mcp_reader.py

@@ -7,6 +7,7 @@ for indexing in LEANN. It supports various Slack MCP server implementations and
 flexible message processing options.
 """
 
+import ast
 import asyncio
 import json
 import logging
@@ -146,16 +147,16 @@ class SlackMCPReader:
                     match = re.search(r"'error':\s*(\{[^}]+\})", str(e))
                     if match:
                         try:
-                            error_dict = eval(match.group(1))
-                        except (ValueError, SyntaxError, NameError):
+                            error_dict = ast.literal_eval(match.group(1))
+                        except (ValueError, SyntaxError):
                             pass
                     else:
                         # Try alternative format
                         match = re.search(r"Failed to fetch messages:\s*(\{[^}]+\})", str(e))
                         if match:
                             try:
-                                error_dict = eval(match.group(1))
-                            except (ValueError, SyntaxError, NameError):
+                                error_dict = ast.literal_eval(match.group(1))
+                            except (ValueError, SyntaxError):
                                 pass
 
                 if self._is_cache_sync_error(error_dict):

docs/configuration-guide.md

@@ -158,6 +158,95 @@ builder.build_index("./indexes/my-notes", chunks)
 
 `embedding_options` is persisted to the index `meta.json`, so subsequent `LeannSearcher` or `LeannChat` sessions automatically reuse the same provider settings (the embedding server manager forwards them to the provider for you).
 
+## Optional Embedding Features
+
+### Task-Specific Prompt Templates
+
+Some embedding models are trained with task-specific prompts to differentiate between documents and queries. The most notable example is **Google's EmbeddingGemma**, which requires different prompts depending on the use case:
+
+- **Indexing documents**: `"title: none | text: "`
+- **Search queries**: `"task: search result | query: "`
+
+LEANN supports automatic prompt prepending via the `--embedding-prompt-template` flag:
+
+```bash
+# Build index with EmbeddingGemma (via LM Studio or Ollama)
+leann build my-docs \
+  --docs ./documents \
+  --embedding-mode openai \
+  --embedding-model text-embedding-embeddinggemma-300m-qat \
+  --embedding-api-base http://localhost:1234/v1 \
+  --embedding-prompt-template "title: none | text: " \
+  --force
+
+# Search with query-specific prompt
+leann search my-docs \
+  --query "What is quantum computing?" \
+  --embedding-prompt-template "task: search result | query: "
+```
+
+**Important Notes:**
+- **Only use with compatible models**: EmbeddingGemma and similar task-specific models
+- **NOT for regular models**: Adding prompts to models like `nomic-embed-text`, `text-embedding-3-small`, or `bge-base-en-v1.5` will corrupt embeddings
+- **Template is saved**: Build-time templates are saved to `.meta.json` for reference
+- **Flexible prompts**: You can use any prompt string, or leave it empty (`""`)
+
+**Python API:**
+```python
+from leann.api import LeannBuilder
+
+builder = LeannBuilder(
+    embedding_mode="openai",
+    embedding_model="text-embedding-embeddinggemma-300m-qat",
+    embedding_options={
+        "base_url": "http://localhost:1234/v1",
+        "api_key": "lm-studio",
+        "prompt_template": "title: none | text: ",
+    },
+)
+builder.build_index("./indexes/my-docs", chunks)
+```
+
+**References:**
+- [HuggingFace Blog: EmbeddingGemma](https://huggingface.co/blog/embeddinggemma) - Technical details
+
+### LM Studio Auto-Detection (Optional)
+
+When using LM Studio with the OpenAI-compatible API, LEANN can optionally auto-detect model context lengths via the LM Studio SDK. This eliminates manual configuration for token limits.
+
+**Prerequisites:**
+```bash
+# Install Node.js (if not already installed)
+# Then install the LM Studio SDK globally
+npm install -g @lmstudio/sdk
+```
+
+**How it works:**
+1. LEANN detects LM Studio URLs (`:1234`, `lmstudio` in URL)
+2. Queries model metadata via Node.js subprocess
+3. Automatically unloads model after query (respects your JIT auto-evict settings)
+4. Falls back to static registry if SDK unavailable
+
+**No configuration needed** - it works automatically when SDK is installed:
+
+```bash
+leann build my-docs \
+  --docs ./documents \
+  --embedding-mode openai \
+  --embedding-model text-embedding-nomic-embed-text-v1.5 \
+  --embedding-api-base http://localhost:1234/v1
+  # Context length auto-detected if SDK available
+  # Falls back to registry (2048) if not
+```
+
+**Benefits:**
+- ✅ Automatic token limit detection
+- ✅ Respects LM Studio JIT auto-evict settings
+- ✅ No manual registry maintenance
+- ✅ Graceful fallback if SDK unavailable
+
+**Note:** This is completely optional. LEANN works perfectly fine without the SDK using the built-in token limit registry.
+
 ## Index Selection: Matching Your Scale
 
 ### HNSW (Hierarchical Navigable Small World)

docs/faq.md

@@ -8,3 +8,51 @@ You can speed up the process by using a lightweight embedding model. Add this to
 --embedding-model sentence-transformers/all-MiniLM-L6-v2
 ```
 **Model sizes:** `all-MiniLM-L6-v2` (30M parameters), `facebook/contriever` (~100M parameters), `Qwen3-0.6B` (600M parameters)
+
+## 2. When should I use prompt templates?
+
+**Use prompt templates ONLY with task-specific embedding models** like Google's EmbeddingGemma. These models are specially trained to use different prompts for documents vs queries.
+
+**DO NOT use with regular models** like `nomic-embed-text`, `text-embedding-3-small`, or `bge-base-en-v1.5` - adding prompts to these models will corrupt the embeddings.
+
+**Example usage with EmbeddingGemma:**
+```bash
+# Build with document prompt
+leann build my-docs --embedding-prompt-template "title: none | text: "
+
+# Search with query prompt
+leann search my-docs --query "your question" --embedding-prompt-template "task: search result | query: "
+```
+
+See the [Configuration Guide: Task-Specific Prompt Templates](configuration-guide.md#task-specific-prompt-templates) for detailed usage.
+
+## 3. Why is LM Studio loading multiple copies of my model?
+
+This was fixed in recent versions. LEANN now properly unloads models after querying metadata, respecting your LM Studio JIT auto-evict settings.
+
+**If you still see duplicates:**
+- Update to the latest LEANN version
+- Restart LM Studio to clear loaded models
+- Check that you have JIT auto-evict enabled in LM Studio settings
+
+**How it works now:**
+1. LEANN loads model temporarily to get context length
+2. Immediately unloads after query
+3. LM Studio JIT loads model on-demand for actual embeddings
+4. Auto-evicts per your settings
+
+## 4. Do I need Node.js and @lmstudio/sdk?
+
+**No, it's completely optional.** LEANN works perfectly fine without them using a built-in token limit registry.
+
+**Benefits if you install it:**
+- Automatic context length detection for LM Studio models
+- No manual registry maintenance
+- Always gets accurate token limits from the model itself
+
+**To install (optional):**
+```bash
+npm install -g @lmstudio/sdk
+```
+
+See [Configuration Guide: LM Studio Auto-Detection](configuration-guide.md#lm-studio-auto-detection-optional) for details.

packages/leann-backend-diskann/pyproject.toml

@@ -4,8 +4,8 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "leann-backend-diskann"
-version = "0.3.4"
-dependencies = ["leann-core==0.3.4", "numpy", "protobuf>=3.19.0"]
+version = "0.3.5"
+dependencies = ["leann-core==0.3.5", "numpy", "protobuf>=3.19.0"]
 
 [tool.scikit-build]
 # Key: simplified CMake path

packages/leann-backend-hnsw/pyproject.toml

@@ -6,10 +6,10 @@ build-backend = "scikit_build_core.build"
 
 [project]
 name = "leann-backend-hnsw"
-version = "0.3.4"
+version = "0.3.5"
 description = "Custom-built HNSW (Faiss) backend for the Leann toolkit."
 dependencies = [
-    "leann-core==0.3.4",
+    "leann-core==0.3.5",
     "numpy",
     "pyzmq>=23.0.0",
     "msgpack>=1.0.0",

packages/leann-core/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "leann-core"
-version = "0.3.4"
+version = "0.3.5"
 description = "Core API and plugin system for LEANN"
 readme = "README.md"
 requires-python = ">=3.9"

packages/leann-core/src/leann/api.py

@@ -916,6 +916,7 @@ class LeannSearcher:
         metadata_filters: Optional[dict[str, dict[str, Union[str, int, float, bool, list]]]] = None,
         batch_size: int = 0,
         use_grep: bool = False,
+        provider_options: Optional[dict[str, Any]] = None,
         **kwargs,
     ) -> list[SearchResult]:
         """
@@ -979,10 +980,24 @@ class LeannSearcher:
 
         start_time = time.time()
 
+        # Extract query template from stored embedding_options with fallback chain:
+        # 1. Check provider_options override (highest priority)
+        # 2. Check query_prompt_template (new format)
+        # 3. Check prompt_template (old format for backward compat)
+        # 4. None (no template)
+        query_template = None
+        if provider_options and "prompt_template" in provider_options:
+            query_template = provider_options["prompt_template"]
+        elif "query_prompt_template" in self.embedding_options:
+            query_template = self.embedding_options["query_prompt_template"]
+        elif "prompt_template" in self.embedding_options:
+            query_template = self.embedding_options["prompt_template"]
+
         query_embedding = self.backend_impl.compute_query_embedding(
             query,
             use_server_if_available=recompute_embeddings,
             zmq_port=zmq_port,
+            query_template=query_template,
         )
         logger.info(f"  Generated embedding shape: {query_embedding.shape}")
         embedding_time = time.time() - start_time

packages/leann-core/src/leann/cli.py

@@ -144,6 +144,18 @@ Examples:
             default=None,
             help="API key for embedding service (defaults to OPENAI_API_KEY)",
         )
+        build_parser.add_argument(
+            "--embedding-prompt-template",
+            type=str,
+            default=None,
+            help="Prompt template to prepend to all texts for embedding (e.g., 'query: ' for search)",
+        )
+        build_parser.add_argument(
+            "--query-prompt-template",
+            type=str,
+            default=None,
+            help="Prompt template for queries (different from build template for task-specific models)",
+        )
         build_parser.add_argument(
             "--force", "-f", action="store_true", help="Force rebuild existing index"
         )
@@ -260,6 +272,12 @@ Examples:
             action="store_true",
             help="Display file paths and metadata in search results",
         )
+        search_parser.add_argument(
+            "--embedding-prompt-template",
+            type=str,
+            default=None,
+            help="Prompt template to prepend to query for embedding (e.g., 'query: ' for search)",
+        )
 
         # Ask command
         ask_parser = subparsers.add_parser("ask", help="Ask questions")
@@ -1162,6 +1180,11 @@ Examples:
                             print(f"Warning: Could not process {file_path}: {e}")
 
             # Load other file types with default reader
+            # Exclude PDFs from code_extensions if they were already processed separately
+            other_file_extensions = code_extensions
+            if should_process_pdfs and ".pdf" in code_extensions:
+                other_file_extensions = [ext for ext in code_extensions if ext != ".pdf"]
+
             try:
                 # Create a custom file filter function using our PathSpec
                 def file_filter(
@@ -1177,15 +1200,19 @@ Examples:
                     except (ValueError, OSError):
                         return True  # Include files that can't be processed
 
-                other_docs = SimpleDirectoryReader(
-                    docs_dir,
-                    recursive=True,
-                    encoding="utf-8",
-                    required_exts=code_extensions,
-                    file_extractor={},  # Use default extractors
-                    exclude_hidden=not include_hidden,
-                    filename_as_id=True,
-                ).load_data(show_progress=True)
+                # Only load other file types if there are extensions to process
+                if other_file_extensions:
+                    other_docs = SimpleDirectoryReader(
+                        docs_dir,
+                        recursive=True,
+                        encoding="utf-8",
+                        required_exts=other_file_extensions,
+                        file_extractor={},  # Use default extractors
+                        exclude_hidden=not include_hidden,
+                        filename_as_id=True,
+                    ).load_data(show_progress=True)
+                else:
+                    other_docs = []
 
                 # Filter documents after loading based on gitignore rules
                 filtered_docs = []
@@ -1398,6 +1425,14 @@ Examples:
             resolved_embedding_key = resolve_openai_api_key(args.embedding_api_key)
             if resolved_embedding_key:
                 embedding_options["api_key"] = resolved_embedding_key
+        if args.query_prompt_template:
+            # New format: separate templates
+            if args.embedding_prompt_template:
+                embedding_options["build_prompt_template"] = args.embedding_prompt_template
+            embedding_options["query_prompt_template"] = args.query_prompt_template
+        elif args.embedding_prompt_template:
+            # Old format: single template (backward compat)
+            embedding_options["prompt_template"] = args.embedding_prompt_template
 
         builder = LeannBuilder(
             backend_name=args.backend_name,
@@ -1519,6 +1554,11 @@ Examples:
                         print("Invalid input. Aborting search.")
                         return
 
+        # Build provider_options for runtime override
+        provider_options = {}
+        if args.embedding_prompt_template:
+            provider_options["prompt_template"] = args.embedding_prompt_template
+
         searcher = LeannSearcher(index_path=index_path)
         results = searcher.search(
             query,
@@ -1528,6 +1568,7 @@ Examples:
             prune_ratio=args.prune_ratio,
             recompute_embeddings=args.recompute_embeddings,
             pruning_strategy=args.pruning_strategy,
+            provider_options=provider_options if provider_options else None,
         )
 
         print(f"Search results for '{query}' (top {len(results)}):")

packages/leann-core/src/leann/embedding_compute.py

@@ -4,8 +4,10 @@ Consolidates all embedding computation logic using SentenceTransformer
 Preserves all optimization parameters to ensure performance
 """
 
+import json
 import logging
 import os
+import subprocess
 import time
 from typing import Any, Optional
 
@@ -40,6 +42,11 @@ EMBEDDING_MODEL_LIMITS = {
     "text-embedding-ada-002": 8192,
 }
 
+# Runtime cache for dynamically discovered token limits
+# Key: (model_name, base_url), Value: token_limit
+# Prevents repeated SDK/API calls for the same model
+_token_limit_cache: dict[tuple[str, str], int] = {}
+
 
 def get_model_token_limit(
     model_name: str,
@@ -49,6 +56,7 @@ def get_model_token_limit(
     """
     Get token limit for a given embedding model.
     Uses hybrid approach: dynamic discovery for Ollama, registry fallback for others.
+    Caches discovered limits to prevent repeated API/SDK calls.
 
     Args:
         model_name: Name of the embedding model
@@ -58,12 +66,33 @@ def get_model_token_limit(
     Returns:
         Token limit for the model in tokens
     """
+    # Check cache first to avoid repeated SDK/API calls
+    cache_key = (model_name, base_url or "")
+    if cache_key in _token_limit_cache:
+        cached_limit = _token_limit_cache[cache_key]
+        logger.debug(f"Using cached token limit for {model_name}: {cached_limit}")
+        return cached_limit
+
     # Try Ollama dynamic discovery if base_url provided
     if base_url:
         # Detect Ollama servers by port or "ollama" in URL
         if "11434" in base_url or "ollama" in base_url.lower():
             limit = _query_ollama_context_limit(model_name, base_url)
             if limit:
+                _token_limit_cache[cache_key] = limit
+                return limit
+
+        # Try LM Studio SDK discovery
+        if "1234" in base_url or "lmstudio" in base_url.lower() or "lm.studio" in base_url.lower():
+            # Convert HTTP to WebSocket URL
+            ws_url = base_url.replace("https://", "wss://").replace("http://", "ws://")
+            # Remove /v1 suffix if present
+            if ws_url.endswith("/v1"):
+                ws_url = ws_url[:-3]
+
+            limit = _query_lmstudio_context_limit(model_name, ws_url)
+            if limit:
+                _token_limit_cache[cache_key] = limit
                 return limit
 
     # Fallback to known model registry with version handling (from PR #154)
@@ -72,19 +101,25 @@ def get_model_token_limit(
 
     # Check exact match first
     if model_name in EMBEDDING_MODEL_LIMITS:
-        return EMBEDDING_MODEL_LIMITS[model_name]
+        limit = EMBEDDING_MODEL_LIMITS[model_name]
+        _token_limit_cache[cache_key] = limit
+        return limit
 
     # Check base name match
     if base_model_name in EMBEDDING_MODEL_LIMITS:
-        return EMBEDDING_MODEL_LIMITS[base_model_name]
+        limit = EMBEDDING_MODEL_LIMITS[base_model_name]
+        _token_limit_cache[cache_key] = limit
+        return limit
 
     # Check partial matches for common patterns
-    for known_model, limit in EMBEDDING_MODEL_LIMITS.items():
+    for known_model, registry_limit in EMBEDDING_MODEL_LIMITS.items():
         if known_model in base_model_name or base_model_name in known_model:
-            return limit
+            _token_limit_cache[cache_key] = registry_limit
+            return registry_limit
 
     # Default fallback
     logger.warning(f"Unknown model '{model_name}', using default {default} token limit")
+    _token_limit_cache[cache_key] = default
     return default
 
 
@@ -185,6 +220,91 @@ def _query_ollama_context_limit(model_name: str, base_url: str) -> Optional[int]
     return None
 
 
+def _query_lmstudio_context_limit(model_name: str, base_url: str) -> Optional[int]:
+    """
+    Query LM Studio SDK for model context length via Node.js subprocess.
+
+    Args:
+        model_name: Name of the LM Studio model
+        base_url: Base URL of the LM Studio server (WebSocket format, e.g., "ws://localhost:1234")
+
+    Returns:
+        Context limit in tokens if found, None otherwise
+    """
+    # Inline JavaScript using @lmstudio/sdk
+    # Note: Load model temporarily for metadata, then unload to respect JIT auto-evict
+    js_code = f"""
+    const {{ LMStudioClient }} = require('@lmstudio/sdk');
+    (async () => {{
+        try {{
+            const client = new LMStudioClient({{ baseUrl: '{base_url}' }});
+            const model = await client.embedding.load('{model_name}', {{ verbose: false }});
+            const contextLength = await model.getContextLength();
+            await model.unload();  // Unload immediately to respect JIT auto-evict settings
+            console.log(JSON.stringify({{ contextLength, identifier: '{model_name}' }}));
+        }} catch (error) {{
+            console.error(JSON.stringify({{ error: error.message }}));
+            process.exit(1);
+        }}
+    }})();
+    """
+
+    try:
+        # Set NODE_PATH to include global modules for @lmstudio/sdk resolution
+        env = os.environ.copy()
+
+        # Try to get npm global root (works with nvm, brew node, etc.)
+        try:
+            npm_root = subprocess.run(
+                ["npm", "root", "-g"],
+                capture_output=True,
+                text=True,
+                timeout=5,
+            )
+            if npm_root.returncode == 0:
+                global_modules = npm_root.stdout.strip()
+                # Append to existing NODE_PATH if present
+                existing_node_path = env.get("NODE_PATH", "")
+                env["NODE_PATH"] = (
+                    f"{global_modules}:{existing_node_path}"
+                    if existing_node_path
+                    else global_modules
+                )
+        except Exception:
+            # If npm not available, continue with existing NODE_PATH
+            pass
+
+        result = subprocess.run(
+            ["node", "-e", js_code],
+            capture_output=True,
+            text=True,
+            timeout=10,
+            env=env,
+        )
+
+        if result.returncode != 0:
+            logger.debug(f"LM Studio SDK error: {result.stderr}")
+            return None
+
+        data = json.loads(result.stdout)
+        context_length = data.get("contextLength")
+
+        if context_length and context_length > 0:
+            logger.info(f"LM Studio SDK detected {model_name} context length: {context_length}")
+            return context_length
+
+    except FileNotFoundError:
+        logger.debug("Node.js not found - install Node.js for LM Studio SDK features")
+    except subprocess.TimeoutExpired:
+        logger.debug("LM Studio SDK query timeout")
+    except json.JSONDecodeError:
+        logger.debug("LM Studio SDK returned invalid JSON")
+    except Exception as e:
+        logger.debug(f"LM Studio SDK query failed: {e}")
+
+    return None
+
+
 # Global model cache to avoid repeated loading
 _model_cache: dict[str, Any] = {}
 
@@ -232,6 +352,7 @@ def compute_embeddings(
             model_name,
             base_url=provider_options.get("base_url"),
             api_key=provider_options.get("api_key"),
+            provider_options=provider_options,
         )
     elif mode == "mlx":
         return compute_embeddings_mlx(texts, model_name)
@@ -241,6 +362,7 @@ def compute_embeddings(
             model_name,
             is_build=is_build,
             host=provider_options.get("host"),
+            provider_options=provider_options,
         )
     elif mode == "gemini":
         return compute_embeddings_gemini(texts, model_name, is_build=is_build)
@@ -579,6 +701,7 @@ def compute_embeddings_openai(
     model_name: str,
     base_url: Optional[str] = None,
     api_key: Optional[str] = None,
+    provider_options: Optional[dict[str, Any]] = None,
 ) -> np.ndarray:
     # TODO: @yichuan-w add progress bar only in build mode
     """Compute embeddings using OpenAI API"""
@@ -597,26 +720,40 @@ def compute_embeddings_openai(
             f"Found {invalid_count} empty/invalid text(s) in input. Upstream should filter before calling OpenAI."
         )
 
-    resolved_base_url = resolve_openai_base_url(base_url)
-    resolved_api_key = resolve_openai_api_key(api_key)
+    # Extract base_url and api_key from provider_options if not provided directly
+    provider_options = provider_options or {}
+    effective_base_url = base_url or provider_options.get("base_url")
+    effective_api_key = api_key or provider_options.get("api_key")
+
+    resolved_base_url = resolve_openai_base_url(effective_base_url)
+    resolved_api_key = resolve_openai_api_key(effective_api_key)
 
     if not resolved_api_key:
         raise RuntimeError("OPENAI_API_KEY environment variable not set")
 
-    # Cache OpenAI client
-    cache_key = f"openai_client::{resolved_base_url}"
-    if cache_key in _model_cache:
-        client = _model_cache[cache_key]
-    else:
-        client = openai.OpenAI(api_key=resolved_api_key, base_url=resolved_base_url)
-        _model_cache[cache_key] = client
-        logger.info("OpenAI client cached")
+    # Create OpenAI client
+    client = openai.OpenAI(api_key=resolved_api_key, base_url=resolved_base_url)
 
     logger.info(
         f"Computing embeddings for {len(texts)} texts using OpenAI API, model: '{model_name}'"
     )
     print(f"len of texts: {len(texts)}")
 
+    # Apply prompt template if provided
+    # Priority: build_prompt_template (new format) > prompt_template (old format)
+    prompt_template = provider_options.get("build_prompt_template") or provider_options.get(
+        "prompt_template"
+    )
+
+    if prompt_template:
+        logger.warning(f"Applying prompt template: '{prompt_template}'")
+        texts = [f"{prompt_template}{text}" for text in texts]
+
+    # Query token limit and apply truncation
+    token_limit = get_model_token_limit(model_name, base_url=effective_base_url)
+    logger.info(f"Using token limit: {token_limit} for model '{model_name}'")
+    texts = truncate_to_token_limit(texts, token_limit)
+
     # OpenAI has limits on batch size and input length
     max_batch_size = 800  # Conservative batch size because the token limit is 300K
     all_embeddings = []
@@ -647,7 +784,15 @@ def compute_embeddings_openai(
         try:
             response = client.embeddings.create(model=model_name, input=batch_texts)
             batch_embeddings = [embedding.embedding for embedding in response.data]
-            all_embeddings.extend(batch_embeddings)
+
+            # Verify we got the expected number of embeddings
+            if len(batch_embeddings) != len(batch_texts):
+                logger.warning(
+                    f"Expected {len(batch_texts)} embeddings but got {len(batch_embeddings)}"
+                )
+
+            # Only take the number of embeddings that match the batch size
+            all_embeddings.extend(batch_embeddings[: len(batch_texts)])
         except Exception as e:
             logger.error(f"Batch {i} failed: {e}")
             raise
@@ -737,6 +882,7 @@ def compute_embeddings_ollama(
     model_name: str,
     is_build: bool = False,
     host: Optional[str] = None,
+    provider_options: Optional[dict[str, Any]] = None,
 ) -> np.ndarray:
     """
     Compute embeddings using Ollama API with true batch processing.
@@ -749,6 +895,7 @@ def compute_embeddings_ollama(
         model_name: Ollama model name (e.g., "nomic-embed-text", "mxbai-embed-large")
         is_build: Whether this is a build operation (shows progress bar)
         host: Ollama host URL (defaults to environment or http://localhost:11434)
+        provider_options: Optional provider-specific options (e.g., prompt_template)
 
     Returns:
         Normalized embeddings array, shape: (len(texts), embedding_dim)
@@ -885,6 +1032,17 @@ def compute_embeddings_ollama(
 
     logger.info(f"Using batch size: {batch_size} for true batch processing")
 
+    # Apply prompt template if provided
+    provider_options = provider_options or {}
+    # Priority: build_prompt_template (new format) > prompt_template (old format)
+    prompt_template = provider_options.get("build_prompt_template") or provider_options.get(
+        "prompt_template"
+    )
+
+    if prompt_template:
+        logger.warning(f"Applying prompt template: '{prompt_template}'")
+        texts = [f"{prompt_template}{text}" for text in texts]
+
     # Get model token limit and apply truncation before batching
     token_limit = get_model_token_limit(model_name, base_url=resolved_host)
     logger.info(f"Model '{model_name}' token limit: {token_limit}")

packages/leann-core/src/leann/interface.py

@@ -77,6 +77,7 @@ class LeannBackendSearcherInterface(ABC):
         query: str,
         use_server_if_available: bool = True,
         zmq_port: Optional[int] = None,
+        query_template: Optional[str] = None,
     ) -> np.ndarray:
         """Compute embedding for a query string
 
@@ -84,6 +85,7 @@ class LeannBackendSearcherInterface(ABC):
             query: The query string to embed
             zmq_port: ZMQ port for embedding server
             use_server_if_available: Whether to try using embedding server first
+            query_template: Optional prompt template to prepend to query
 
         Returns:
             Query embedding as numpy array with shape (1, D)

packages/leann-core/src/leann/registry.py

@@ -33,6 +33,8 @@ def autodiscover_backends():
     discovered_backends = []
     for dist in importlib.metadata.distributions():
         dist_name = dist.metadata["name"]
+        if dist_name is None:
+            continue
         if dist_name.startswith("leann-backend-"):
             backend_module_name = dist_name.replace("-", "_")
             discovered_backends.append(backend_module_name)

packages/leann-core/src/leann/searcher_base.py

@@ -71,6 +71,15 @@ class BaseSearcher(LeannBackendSearcherInterface, ABC):
             or "mips"
         )
 
+        # Filter out ALL prompt templates from provider_options during search
+        # Templates are applied in compute_query_embedding (line 109-110) BEFORE server call
+        # The server should never apply templates during search to avoid double-templating
+        search_provider_options = {
+            k: v
+            for k, v in self.embedding_options.items()
+            if k not in ("build_prompt_template", "query_prompt_template", "prompt_template")
+        }
+
         server_started, actual_port = self.embedding_server_manager.start_server(
             port=port,
             model_name=self.embedding_model,
@@ -78,7 +87,7 @@ class BaseSearcher(LeannBackendSearcherInterface, ABC):
             passages_file=passages_source_file,
             distance_metric=distance_metric,
             enable_warmup=kwargs.get("enable_warmup", False),
-            provider_options=self.embedding_options,
+            provider_options=search_provider_options,
         )
         if not server_started:
             raise RuntimeError(f"Failed to start embedding server on port {actual_port}")
@@ -90,6 +99,7 @@ class BaseSearcher(LeannBackendSearcherInterface, ABC):
         query: str,
         use_server_if_available: bool = True,
         zmq_port: int = 5557,
+        query_template: Optional[str] = None,
     ) -> np.ndarray:
         """
         Compute embedding for a query string.
@@ -98,10 +108,16 @@ class BaseSearcher(LeannBackendSearcherInterface, ABC):
             query: The query string to embed
             zmq_port: ZMQ port for embedding server
             use_server_if_available: Whether to try using embedding server first
+            query_template: Optional prompt template to prepend to query
 
         Returns:
             Query embedding as numpy array
         """
+        # Apply query template BEFORE any computation path
+        # This ensures template is applied consistently for both server and fallback paths
+        if query_template:
+            query = f"{query_template}{query}"
+
         # Try to use embedding server if available and requested
         if use_server_if_available:
             try:

packages/leann/pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "leann"
-version = "0.3.4"
+version = "0.3.5"
 description = "LEANN - The smallest vector index in the world. RAG Everything with LEANN!"
 readme = "README.md"
 requires-python = ">=3.9"

pyproject.toml

@@ -69,7 +69,8 @@ diskann = [
 # Add a new optional dependency group for document processing
 documents = [
     "beautifulsoup4>=4.13.0",  # For HTML parsing
-    "python-docx>=0.8.11",     # For Word documents
+    "python-docx>=0.8.11",     # For Word documents (creating/editing)
+    "docx2txt>=0.9",           # For Word documents (text extraction)
     "openpyxl>=3.1.0",         # For Excel files
     "pandas>=2.2.0",           # For data processing
 ]
@@ -164,6 +165,7 @@ python_functions = ["test_*"]
 markers = [
     "slow: marks tests as slow (deselect with '-m \"not slow\"')",
     "openai: marks tests that require OpenAI API key",
+    "integration: marks tests that require live services (Ollama, LM Studio, etc.)",
 ]
 timeout = 300  # Reduced from 600s (10min) to 300s (5min) for CI safety
 addopts = [

tests/README.md

@@ -36,6 +36,14 @@ Tests DiskANN graph partitioning functionality:
 - Includes performance comparison between DiskANN (with partition) and HNSW
 - **Note**: These tests are skipped in CI due to hardware requirements and computation time
 
+### `test_prompt_template_e2e.py`
+Integration tests for prompt template feature with live embedding services:
+- Tests prompt template prepending with EmbeddingGemma (OpenAI-compatible API via LM Studio)
+- Tests hybrid token limit discovery (Ollama dynamic detection, registry fallback, default)
+- Tests LM Studio SDK bridge for automatic context length detection (requires Node.js + @lmstudio/sdk)
+- **Note**: These tests require live services (LM Studio, Ollama) and are marked with `@pytest.mark.integration`
+- **Important**: Prompt templates are ONLY for EmbeddingGemma and similar task-specific models, NOT regular embedding models
+
 ## Running Tests
 
 ### Install test dependencies:
@@ -66,6 +74,12 @@ pytest tests/ -m "not openai"
 # Skip slow tests
 pytest tests/ -m "not slow"
 
+# Skip integration tests (that require live services)
+pytest tests/ -m "not integration"
+
+# Run only integration tests (requires LM Studio or Ollama running)
+pytest tests/test_prompt_template_e2e.py -v -s
+
 # Run DiskANN partition tests (requires local machine, not CI)
 pytest tests/test_diskann_partition.py
 ```
@@ -101,6 +115,20 @@ The `pytest.ini` file configures:
 - Custom markers for slow and OpenAI tests
 - Verbose output with short tracebacks
 
+### Integration Test Prerequisites
+
+Integration tests (`test_prompt_template_e2e.py`) require live services:
+
+**Required:**
+- LM Studio running at `http://localhost:1234` with EmbeddingGemma model loaded
+
+**Optional:**
+- Ollama running at `http://localhost:11434` for token limit detection tests
+- Node.js + @lmstudio/sdk installed (`npm install -g @lmstudio/sdk`) for SDK bridge tests
+
+Tests gracefully skip if services are unavailable.
+
 ### Known Issues
 
 - OpenAI tests are automatically skipped if no API key is provided
+- Integration tests require live embedding services and may fail due to proxy settings (set `unset ALL_PROXY all_proxy` if needed)

tests/test_cli_prompt_template.py

@@ -0,0 +1,533 @@
+"""
+Tests for CLI argument integration of --embedding-prompt-template.
+
+These tests verify that:
+1. The --embedding-prompt-template flag is properly registered on build and search commands
+2. The template value flows from CLI args to embedding_options dict
+3. The template is passed through to compute_embeddings() function
+4. Default behavior (no flag) is handled correctly
+"""
+
+from unittest.mock import Mock, patch
+
+from leann.cli import LeannCLI
+
+
+class TestCLIPromptTemplateArgument:
+    """Tests for --embedding-prompt-template on build and search commands."""
+
+    def test_commands_accept_prompt_template_argument(self):
+        """Verify that build and search parsers accept --embedding-prompt-template flag."""
+        cli = LeannCLI()
+        parser = cli.create_parser()
+        template_value = "search_query: "
+
+        # Test build command
+        build_args = parser.parse_args(
+            [
+                "build",
+                "test-index",
+                "--docs",
+                "/tmp/test-docs",
+                "--embedding-prompt-template",
+                template_value,
+            ]
+        )
+        assert build_args.command == "build"
+        assert hasattr(build_args, "embedding_prompt_template"), (
+            "build command should have embedding_prompt_template attribute"
+        )
+        assert build_args.embedding_prompt_template == template_value
+
+        # Test search command
+        search_args = parser.parse_args(
+            ["search", "test-index", "my query", "--embedding-prompt-template", template_value]
+        )
+        assert search_args.command == "search"
+        assert hasattr(search_args, "embedding_prompt_template"), (
+            "search command should have embedding_prompt_template attribute"
+        )
+        assert search_args.embedding_prompt_template == template_value
+
+    def test_commands_default_to_none(self):
+        """Verify default value is None when flag not provided (backward compatibility)."""
+        cli = LeannCLI()
+        parser = cli.create_parser()
+
+        # Test build command default
+        build_args = parser.parse_args(["build", "test-index", "--docs", "/tmp/test-docs"])
+        assert hasattr(build_args, "embedding_prompt_template"), (
+            "build command should have embedding_prompt_template attribute"
+        )
+        assert build_args.embedding_prompt_template is None, (
+            "Build default value should be None when flag not provided"
+        )
+
+        # Test search command default
+        search_args = parser.parse_args(["search", "test-index", "my query"])
+        assert hasattr(search_args, "embedding_prompt_template"), (
+            "search command should have embedding_prompt_template attribute"
+        )
+        assert search_args.embedding_prompt_template is None, (
+            "Search default value should be None when flag not provided"
+        )
+
+
+class TestBuildCommandPromptTemplateArgumentExtras:
+    """Additional build-specific tests for prompt template argument."""
+
+    def test_build_command_prompt_template_with_multiword_value(self):
+        """
+        Verify that template values with spaces are handled correctly.
+
+        Templates like "search_document: " or "Represent this sentence for searching: "
+        should be accepted as a single string argument.
+        """
+        cli = LeannCLI()
+        parser = cli.create_parser()
+
+        template = "Represent this sentence for searching: "
+        args = parser.parse_args(
+            [
+                "build",
+                "test-index",
+                "--docs",
+                "/tmp/test-docs",
+                "--embedding-prompt-template",
+                template,
+            ]
+        )
+
+        assert args.embedding_prompt_template == template
+
+
+class TestPromptTemplateStoredInEmbeddingOptions:
+    """Tests for template storage in embedding_options dict."""
+
+    @patch("leann.cli.LeannBuilder")
+    def test_prompt_template_stored_in_embedding_options_on_build(
+        self, mock_builder_class, tmp_path
+    ):
+        """
+        Verify that when --embedding-prompt-template is provided to build command,
+        the value is stored in embedding_options dict passed to LeannBuilder.
+
+        This test will fail because the CLI doesn't currently process this argument
+        and add it to embedding_options.
+        """
+        # Setup mocks
+        mock_builder = Mock()
+        mock_builder_class.return_value = mock_builder
+
+        # Create CLI and run build command
+        cli = LeannCLI()
+
+        # Mock load_documents to return a document so builder is created
+        cli.load_documents = Mock(return_value=[{"text": "test content", "metadata": {}}])
+
+        parser = cli.create_parser()
+
+        template = "search_query: "
+        args = parser.parse_args(
+            [
+                "build",
+                "test-index",
+                "--docs",
+                str(tmp_path),
+                "--embedding-prompt-template",
+                template,
+                "--force",  # Force rebuild to ensure LeannBuilder is called
+            ]
+        )
+
+        # Run the build command
+        import asyncio
+
+        asyncio.run(cli.build_index(args))
+
+        # Check that LeannBuilder was called with embedding_options containing prompt_template
+        call_kwargs = mock_builder_class.call_args.kwargs
+        assert "embedding_options" in call_kwargs, "LeannBuilder should receive embedding_options"
+
+        embedding_options = call_kwargs["embedding_options"]
+        assert embedding_options is not None, (
+            "embedding_options should not be None when template provided"
+        )
+        assert "prompt_template" in embedding_options, (
+            "embedding_options should contain 'prompt_template' key"
+        )
+        assert embedding_options["prompt_template"] == template, (
+            f"Template should be '{template}', got {embedding_options.get('prompt_template')}"
+        )
+
+    @patch("leann.cli.LeannBuilder")
+    def test_prompt_template_not_in_options_when_not_provided(self, mock_builder_class, tmp_path):
+        """
+        Verify that when --embedding-prompt-template is NOT provided,
+        embedding_options either doesn't have the key or it's None.
+
+        This ensures we don't pass empty/None values unnecessarily.
+        """
+        # Setup mocks
+        mock_builder = Mock()
+        mock_builder_class.return_value = mock_builder
+
+        cli = LeannCLI()
+
+        # Mock load_documents to return a document so builder is created
+        cli.load_documents = Mock(return_value=[{"text": "test content", "metadata": {}}])
+
+        parser = cli.create_parser()
+
+        args = parser.parse_args(
+            [
+                "build",
+                "test-index",
+                "--docs",
+                str(tmp_path),
+                "--force",  # Force rebuild to ensure LeannBuilder is called
+            ]
+        )
+
+        import asyncio
+
+        asyncio.run(cli.build_index(args))
+
+        # Check that if embedding_options is passed, it doesn't have prompt_template
+        call_kwargs = mock_builder_class.call_args.kwargs
+        if call_kwargs.get("embedding_options"):
+            embedding_options = call_kwargs["embedding_options"]
+            # Either the key shouldn't exist, or it should be None
+            assert (
+                "prompt_template" not in embedding_options
+                or embedding_options["prompt_template"] is None
+            ), "prompt_template should not be set when flag not provided"
+
+    # R1 Tests: Build-time separate template storage
+    @patch("leann.cli.LeannBuilder")
+    def test_build_stores_separate_templates(self, mock_builder_class, tmp_path):
+        """
+        R1 Test 1: Verify that when both --embedding-prompt-template and
+        --query-prompt-template are provided to build command, both values
+        are stored separately in embedding_options dict as build_prompt_template
+        and query_prompt_template.
+
+        This test will fail because:
+        1. CLI doesn't accept --query-prompt-template flag yet
+        2. CLI doesn't store templates as separate build_prompt_template and
+           query_prompt_template keys
+
+        Expected behavior after implementation:
+        - .meta.json contains: {"embedding_options": {
+            "build_prompt_template": "doc: ",
+            "query_prompt_template": "query: "
+          }}
+        """
+        # Setup mocks
+        mock_builder = Mock()
+        mock_builder_class.return_value = mock_builder
+
+        cli = LeannCLI()
+
+        # Mock load_documents to return a document so builder is created
+        cli.load_documents = Mock(return_value=[{"text": "test content", "metadata": {}}])
+
+        parser = cli.create_parser()
+
+        build_template = "doc: "
+        query_template = "query: "
+        args = parser.parse_args(
+            [
+                "build",
+                "test-index",
+                "--docs",
+                str(tmp_path),
+                "--embedding-prompt-template",
+                build_template,
+                "--query-prompt-template",
+                query_template,
+                "--force",
+            ]
+        )
+
+        # Run the build command
+        import asyncio
+
+        asyncio.run(cli.build_index(args))
+
+        # Check that LeannBuilder was called with separate template keys
+        call_kwargs = mock_builder_class.call_args.kwargs
+        assert "embedding_options" in call_kwargs, "LeannBuilder should receive embedding_options"
+
+        embedding_options = call_kwargs["embedding_options"]
+        assert embedding_options is not None, (
+            "embedding_options should not be None when templates provided"
+        )
+
+        assert "build_prompt_template" in embedding_options, (
+            "embedding_options should contain 'build_prompt_template' key"
+        )
+        assert embedding_options["build_prompt_template"] == build_template, (
+            f"build_prompt_template should be '{build_template}'"
+        )
+
+        assert "query_prompt_template" in embedding_options, (
+            "embedding_options should contain 'query_prompt_template' key"
+        )
+        assert embedding_options["query_prompt_template"] == query_template, (
+            f"query_prompt_template should be '{query_template}'"
+        )
+
+        # Old key should NOT be present when using new separate template format
+        assert "prompt_template" not in embedding_options, (
+            "Old 'prompt_template' key should not be present with separate templates"
+        )
+
+    @patch("leann.cli.LeannBuilder")
+    def test_build_backward_compat_single_template(self, mock_builder_class, tmp_path):
+        """
+        R1 Test 2: Verify backward compatibility - when only
+        --embedding-prompt-template is provided (old behavior), it should
+        still be stored as 'prompt_template' in embedding_options.
+
+        This ensures existing workflows continue to work unchanged.
+
+        This test currently passes because it matches existing behavior, but it
+        documents the requirement that this behavior must be preserved after
+        implementing the separate template feature.
+
+        Expected behavior:
+        - .meta.json contains: {"embedding_options": {"prompt_template": "prompt: "}}
+        - No build_prompt_template or query_prompt_template keys
+        """
+        # Setup mocks
+        mock_builder = Mock()
+        mock_builder_class.return_value = mock_builder
+
+        cli = LeannCLI()
+
+        # Mock load_documents to return a document so builder is created
+        cli.load_documents = Mock(return_value=[{"text": "test content", "metadata": {}}])
+
+        parser = cli.create_parser()
+
+        template = "prompt: "
+        args = parser.parse_args(
+            [
+                "build",
+                "test-index",
+                "--docs",
+                str(tmp_path),
+                "--embedding-prompt-template",
+                template,
+                "--force",
+            ]
+        )
+
+        # Run the build command
+        import asyncio
+
+        asyncio.run(cli.build_index(args))
+
+        # Check that LeannBuilder was called with old format
+        call_kwargs = mock_builder_class.call_args.kwargs
+        assert "embedding_options" in call_kwargs, "LeannBuilder should receive embedding_options"
+
+        embedding_options = call_kwargs["embedding_options"]
+        assert embedding_options is not None, (
+            "embedding_options should not be None when template provided"
+        )
+
+        assert "prompt_template" in embedding_options, (
+            "embedding_options should contain old 'prompt_template' key for backward compat"
+        )
+        assert embedding_options["prompt_template"] == template, (
+            f"prompt_template should be '{template}'"
+        )
+
+        # New keys should NOT be present in backward compat mode
+        assert "build_prompt_template" not in embedding_options, (
+            "build_prompt_template should not be present with single template flag"
+        )
+        assert "query_prompt_template" not in embedding_options, (
+            "query_prompt_template should not be present with single template flag"
+        )
+
+    @patch("leann.cli.LeannBuilder")
+    def test_build_no_templates(self, mock_builder_class, tmp_path):
+        """
+        R1 Test 3: Verify that when no template flags are provided,
+        embedding_options has no prompt template keys.
+
+        This ensures clean defaults and no unnecessary keys in .meta.json.
+
+        This test currently passes because it matches existing behavior, but it
+        documents the requirement that this behavior must be preserved after
+        implementing the separate template feature.
+
+        Expected behavior:
+        - .meta.json has no prompt_template, build_prompt_template, or
+          query_prompt_template keys (or embedding_options is empty/None)
+        """
+        # Setup mocks
+        mock_builder = Mock()
+        mock_builder_class.return_value = mock_builder
+
+        cli = LeannCLI()
+
+        # Mock load_documents to return a document so builder is created
+        cli.load_documents = Mock(return_value=[{"text": "test content", "metadata": {}}])
+
+        parser = cli.create_parser()
+
+        args = parser.parse_args(["build", "test-index", "--docs", str(tmp_path), "--force"])
+
+        # Run the build command
+        import asyncio
+
+        asyncio.run(cli.build_index(args))
+
+        # Check that no template keys are present
+        call_kwargs = mock_builder_class.call_args.kwargs
+        if call_kwargs.get("embedding_options"):
+            embedding_options = call_kwargs["embedding_options"]
+
+            # None of the template keys should be present
+            assert "prompt_template" not in embedding_options, (
+                "prompt_template should not be present when no flags provided"
+            )
+            assert "build_prompt_template" not in embedding_options, (
+                "build_prompt_template should not be present when no flags provided"
+            )
+            assert "query_prompt_template" not in embedding_options, (
+                "query_prompt_template should not be present when no flags provided"
+            )
+
+
+class TestPromptTemplateFlowsToComputeEmbeddings:
+    """Tests for template flowing through to compute_embeddings function."""
+
+    @patch("leann.api.compute_embeddings")
+    def test_prompt_template_flows_to_compute_embeddings_via_provider_options(
+        self, mock_compute_embeddings, tmp_path
+    ):
+        """
+        Verify that the prompt template flows from CLI args through LeannBuilder
+        to compute_embeddings() function via provider_options parameter.
+
+        This is an integration test that verifies the complete flow:
+        CLI → embedding_options → LeannBuilder → compute_embeddings(provider_options)
+
+        This test will fail because:
+        1. CLI doesn't capture the argument yet
+        2. embedding_options doesn't include prompt_template
+        3. LeannBuilder doesn't pass it through to compute_embeddings
+        """
+        # Mock compute_embeddings to return dummy embeddings as numpy array
+        import numpy as np
+
+        mock_compute_embeddings.return_value = np.array([[0.1, 0.2, 0.3]], dtype=np.float32)
+
+        # Use real LeannBuilder (not mocked) to test the actual flow
+        cli = LeannCLI()
+
+        # Mock load_documents to return a simple document
+        cli.load_documents = Mock(return_value=[{"text": "test content", "metadata": {}}])
+
+        parser = cli.create_parser()
+
+        template = "search_document: "
+        args = parser.parse_args(
+            [
+                "build",
+                "test-index",
+                "--docs",
+                str(tmp_path),
+                "--embedding-prompt-template",
+                template,
+                "--backend-name",
+                "hnsw",  # Use hnsw backend
+                "--force",  # Force rebuild to ensure index is created
+            ]
+        )
+
+        # This should fail because the flow isn't implemented yet
+        import asyncio
+
+        asyncio.run(cli.build_index(args))
+
+        # Verify compute_embeddings was called with provider_options containing prompt_template
+        assert mock_compute_embeddings.called, "compute_embeddings should have been called"
+
+        # Check the call arguments
+        call_kwargs = mock_compute_embeddings.call_args.kwargs
+        assert "provider_options" in call_kwargs, (
+            "compute_embeddings should receive provider_options parameter"
+        )
+
+        provider_options = call_kwargs["provider_options"]
+        assert provider_options is not None, "provider_options should not be None"
+        assert "prompt_template" in provider_options, (
+            "provider_options should contain prompt_template key"
+        )
+        assert provider_options["prompt_template"] == template, (
+            f"Template should be '{template}', got {provider_options.get('prompt_template')}"
+        )
+
+
+class TestPromptTemplateArgumentHelp:
+    """Tests for argument help text and documentation."""
+
+    def test_build_command_prompt_template_has_help_text(self):
+        """
+        Verify that --embedding-prompt-template has descriptive help text.
+
+        Good help text is crucial for CLI usability.
+        """
+        cli = LeannCLI()
+        parser = cli.create_parser()
+
+        # Get the build subparser
+        # This is a bit tricky - we need to parse to get the help
+        # We'll check that the help includes relevant keywords
+        import io
+        from contextlib import redirect_stdout
+
+        f = io.StringIO()
+        try:
+            with redirect_stdout(f):
+                parser.parse_args(["build", "--help"])
+        except SystemExit:
+            pass  # --help causes sys.exit(0)
+
+        help_text = f.getvalue()
+        assert "--embedding-prompt-template" in help_text, (
+            "Help text should mention --embedding-prompt-template"
+        )
+        # Check for keywords that should be in the help
+        help_lower = help_text.lower()
+        assert any(keyword in help_lower for keyword in ["template", "prompt", "prepend"]), (
+            "Help text should explain what the prompt template does"
+        )
+
+    def test_search_command_prompt_template_has_help_text(self):
+        """
+        Verify that search command also has help text for --embedding-prompt-template.
+        """
+        cli = LeannCLI()
+        parser = cli.create_parser()
+
+        import io
+        from contextlib import redirect_stdout
+
+        f = io.StringIO()
+        try:
+            with redirect_stdout(f):
+                parser.parse_args(["search", "--help"])
+        except SystemExit:
+            pass  # --help causes sys.exit(0)
+
+        help_text = f.getvalue()
+        assert "--embedding-prompt-template" in help_text, (
+            "Search help text should mention --embedding-prompt-template"
+        )

tests/test_embedding_prompt_template.py

@@ -0,0 +1,281 @@
+"""Unit tests for prompt template prepending in OpenAI embeddings.
+
+This test suite defines the contract for prompt template functionality that allows
+users to prepend a consistent prompt to all embedding inputs. These tests verify:
+
+1. Template prepending to all input texts before embedding computation
+2. Graceful handling of None/missing provider_options
+3. Empty string template behavior (no-op)
+4. Logging of template application for observability
+5. Template application before token truncation
+
+All tests are written in Red Phase - they should FAIL initially because the
+implementation does not exist yet.
+"""
+
+from unittest.mock import MagicMock, Mock, patch
+
+import numpy as np
+import pytest
+from leann.embedding_compute import compute_embeddings_openai
+
+
+class TestPromptTemplatePrepending:
+    """Tests for prompt template prepending in compute_embeddings_openai."""
+
+    @pytest.fixture
+    def mock_openai_client(self):
+        """Create mock OpenAI client that captures input texts."""
+        mock_client = MagicMock()
+
+        # Mock the embeddings.create response
+        mock_response = Mock()
+        mock_response.data = [
+            Mock(embedding=[0.1, 0.2, 0.3]),
+            Mock(embedding=[0.4, 0.5, 0.6]),
+        ]
+        mock_client.embeddings.create.return_value = mock_response
+
+        return mock_client
+
+    @pytest.fixture
+    def mock_openai_module(self, mock_openai_client, monkeypatch):
+        """Mock the openai module to return our mock client."""
+        # Mock the API key environment variable
+        monkeypatch.setenv("OPENAI_API_KEY", "fake-test-key-for-mocking")
+
+        # openai is imported inside the function, so we need to patch it there
+        with patch("openai.OpenAI", return_value=mock_openai_client) as mock_openai:
+            yield mock_openai
+
+    def test_prompt_template_prepended_to_all_texts(self, mock_openai_module, mock_openai_client):
+        """Verify template is prepended to all input texts.
+
+        When provider_options contains "prompt_template", that template should
+        be prepended to every text in the input list before sending to OpenAI API.
+
+        This is the core functionality: the template acts as a consistent prefix
+        that provides context or instruction for the embedding model.
+        """
+        texts = ["First document", "Second document"]
+        template = "search_document: "
+        provider_options = {"prompt_template": template}
+
+        # Call compute_embeddings_openai with provider_options
+        result = compute_embeddings_openai(
+            texts=texts,
+            model_name="text-embedding-3-small",
+            provider_options=provider_options,
+        )
+
+        # Verify embeddings.create was called with templated texts
+        mock_openai_client.embeddings.create.assert_called_once()
+        call_args = mock_openai_client.embeddings.create.call_args
+
+        # Extract the input texts sent to API
+        sent_texts = call_args.kwargs["input"]
+
+        # Verify template was prepended to all texts
+        assert len(sent_texts) == 2, "Should send same number of texts"
+        assert sent_texts[0] == "search_document: First document", (
+            "Template should be prepended to first text"
+        )
+        assert sent_texts[1] == "search_document: Second document", (
+            "Template should be prepended to second text"
+        )
+
+        # Verify result is valid embeddings array
+        assert isinstance(result, np.ndarray)
+        assert result.shape == (2, 3), "Should return correct shape"
+
+    def test_template_not_applied_when_missing_or_empty(
+        self, mock_openai_module, mock_openai_client
+    ):
+        """Verify template not applied when provider_options is None, missing key, or empty string.
+
+        This consolidated test covers three scenarios where templates should NOT be applied:
+        1. provider_options is None (default behavior)
+        2. provider_options exists but missing 'prompt_template' key
+        3. prompt_template is explicitly set to empty string ""
+
+        In all cases, texts should be sent to the API unchanged.
+        """
+        # Scenario 1: None provider_options
+        texts = ["Original text one", "Original text two"]
+        result = compute_embeddings_openai(
+            texts=texts,
+            model_name="text-embedding-3-small",
+            provider_options=None,
+        )
+        call_args = mock_openai_client.embeddings.create.call_args
+        sent_texts = call_args.kwargs["input"]
+        assert sent_texts[0] == "Original text one", (
+            "Text should be unchanged with None provider_options"
+        )
+        assert sent_texts[1] == "Original text two"
+        assert isinstance(result, np.ndarray)
+        assert result.shape == (2, 3)
+
+        # Reset mock for next scenario
+        mock_openai_client.reset_mock()
+        mock_response = Mock()
+        mock_response.data = [
+            Mock(embedding=[0.1, 0.2, 0.3]),
+            Mock(embedding=[0.4, 0.5, 0.6]),
+        ]
+        mock_openai_client.embeddings.create.return_value = mock_response
+
+        # Scenario 2: Missing 'prompt_template' key
+        texts = ["Text without template", "Another text"]
+        provider_options = {"base_url": "https://api.openai.com/v1"}
+        result = compute_embeddings_openai(
+            texts=texts,
+            model_name="text-embedding-3-small",
+            provider_options=provider_options,
+        )
+        call_args = mock_openai_client.embeddings.create.call_args
+        sent_texts = call_args.kwargs["input"]
+        assert sent_texts[0] == "Text without template", "Text should be unchanged with missing key"
+        assert sent_texts[1] == "Another text"
+        assert isinstance(result, np.ndarray)
+
+        # Reset mock for next scenario
+        mock_openai_client.reset_mock()
+        mock_openai_client.embeddings.create.return_value = mock_response
+
+        # Scenario 3: Empty string template
+        texts = ["Text one", "Text two"]
+        provider_options = {"prompt_template": ""}
+        result = compute_embeddings_openai(
+            texts=texts,
+            model_name="text-embedding-3-small",
+            provider_options=provider_options,
+        )
+        call_args = mock_openai_client.embeddings.create.call_args
+        sent_texts = call_args.kwargs["input"]
+        assert sent_texts[0] == "Text one", "Empty template should not modify text"
+        assert sent_texts[1] == "Text two"
+        assert isinstance(result, np.ndarray)
+
+    def test_prompt_template_with_multiple_batches(self, mock_openai_module, mock_openai_client):
+        """Verify template is prepended in all batches when texts exceed batch size.
+
+        OpenAI API has batch size limits. When input texts are split into
+        multiple batches, the template should be prepended to texts in every batch.
+
+        This ensures consistency across all API calls.
+        """
+        # Create many texts that will be split into multiple batches
+        texts = [f"Document {i}" for i in range(1000)]
+        template = "passage: "
+        provider_options = {"prompt_template": template}
+
+        # Mock multiple batch responses
+        mock_response = Mock()
+        mock_response.data = [Mock(embedding=[0.1, 0.2, 0.3]) for _ in range(1000)]
+        mock_openai_client.embeddings.create.return_value = mock_response
+
+        result = compute_embeddings_openai(
+            texts=texts,
+            model_name="text-embedding-3-small",
+            provider_options=provider_options,
+        )
+
+        # Verify embeddings.create was called multiple times (batching)
+        assert mock_openai_client.embeddings.create.call_count >= 2, (
+            "Should make multiple API calls for large text list"
+        )
+
+        # Verify template was prepended in ALL batches
+        for call in mock_openai_client.embeddings.create.call_args_list:
+            sent_texts = call.kwargs["input"]
+            for text in sent_texts:
+                assert text.startswith(template), (
+                    f"All texts in all batches should start with template. Got: {text}"
+                )
+
+        # Verify result shape
+        assert result.shape[0] == 1000, "Should return embeddings for all texts"
+
+    def test_prompt_template_with_special_characters(self, mock_openai_module, mock_openai_client):
+        """Verify template with special characters is handled correctly.
+
+        Templates may contain special characters, Unicode, newlines, etc.
+        These should all be prepended correctly without encoding issues.
+        """
+        texts = ["Document content"]
+        # Template with various special characters
+        template = "🔍 Search query [EN]: "
+        provider_options = {"prompt_template": template}
+
+        result = compute_embeddings_openai(
+            texts=texts,
+            model_name="text-embedding-3-small",
+            provider_options=provider_options,
+        )
+
+        # Verify special characters in template were preserved
+        call_args = mock_openai_client.embeddings.create.call_args
+        sent_texts = call_args.kwargs["input"]
+
+        assert sent_texts[0] == "🔍 Search query [EN]: Document content", (
+            "Special characters in template should be preserved"
+        )
+
+        assert isinstance(result, np.ndarray)
+
+    def test_prompt_template_integration_with_existing_validation(
+        self, mock_openai_module, mock_openai_client
+    ):
+        """Verify template works with existing input validation.
+
+        compute_embeddings_openai has validation for empty texts and whitespace.
+        Template prepending should happen AFTER validation, so validation errors
+        are thrown based on original texts, not templated texts.
+
+        This ensures users get clear error messages about their input.
+        """
+        # Empty text should still raise ValueError even with template
+        texts = [""]
+        provider_options = {"prompt_template": "prefix: "}
+
+        with pytest.raises(ValueError, match="empty/invalid"):
+            compute_embeddings_openai(
+                texts=texts,
+                model_name="text-embedding-3-small",
+                provider_options=provider_options,
+            )
+
+    def test_prompt_template_with_api_key_and_base_url(
+        self, mock_openai_module, mock_openai_client
+    ):
+        """Verify template works alongside other provider_options.
+
+        provider_options may contain multiple settings: prompt_template,
+        base_url, api_key. All should work together correctly.
+        """
+        texts = ["Test document"]
+        provider_options = {
+            "prompt_template": "embed: ",
+            "base_url": "https://custom.api.com/v1",
+            "api_key": "test-key-123",
+        }
+
+        result = compute_embeddings_openai(
+            texts=texts,
+            model_name="text-embedding-3-small",
+            provider_options=provider_options,
+        )
+
+        # Verify template was applied
+        call_args = mock_openai_client.embeddings.create.call_args
+        sent_texts = call_args.kwargs["input"]
+        assert sent_texts[0] == "embed: Test document"
+
+        # Verify OpenAI client was created with correct base_url
+        mock_openai_module.assert_called()
+        client_init_kwargs = mock_openai_module.call_args.kwargs
+        assert client_init_kwargs["base_url"] == "https://custom.api.com/v1"
+        assert client_init_kwargs["api_key"] == "test-key-123"
+
+        assert isinstance(result, np.ndarray)

tests/test_lmstudio_bridge.py

@@ -0,0 +1,315 @@
+"""Unit tests for LM Studio TypeScript SDK bridge functionality.
+
+This test suite defines the contract for the LM Studio SDK bridge that queries
+model context length via Node.js subprocess. These tests verify:
+
+1. Successful SDK query returns context length
+2. Graceful fallback when Node.js not installed (FileNotFoundError)
+3. Graceful fallback when SDK not installed (npm error)
+4. Timeout handling (subprocess.TimeoutExpired)
+5. Invalid JSON response handling
+
+All tests are written in Red Phase - they should FAIL initially because the
+`_query_lmstudio_context_limit` function does not exist yet.
+
+The function contract:
+- Inputs: model_name (str), base_url (str, WebSocket format "ws://localhost:1234")
+- Outputs: context_length (int) or None on error
+- Requirements:
+  1. Call Node.js with inline JavaScript using @lmstudio/sdk
+  2. 10-second timeout (accounts for Node.js startup)
+  3. Graceful fallback on any error (returns None, doesn't raise)
+  4. Parse JSON response with contextLength field
+  5. Log errors at debug level (not warning/error)
+"""
+
+import subprocess
+from unittest.mock import Mock
+
+import pytest
+
+# Try to import the function - if it doesn't exist, tests will fail as expected
+try:
+    from leann.embedding_compute import _query_lmstudio_context_limit
+except ImportError:
+    # Function doesn't exist yet (Red Phase) - create a placeholder that will fail
+    def _query_lmstudio_context_limit(*args, **kwargs):
+        raise NotImplementedError(
+            "_query_lmstudio_context_limit not implemented yet - this is the Red Phase"
+        )
+
+
+class TestLMStudioBridge:
+    """Tests for LM Studio TypeScript SDK bridge integration."""
+
+    def test_query_lmstudio_success(self, monkeypatch):
+        """Verify successful SDK query returns context length.
+
+        When the Node.js subprocess successfully queries the LM Studio SDK,
+        it should return a JSON response with contextLength field. The function
+        should parse this and return the integer context length.
+        """
+
+        def mock_run(*args, **kwargs):
+            # Verify timeout is set to 10 seconds
+            assert kwargs.get("timeout") == 10, "Should use 10-second timeout for Node.js startup"
+
+            # Verify capture_output and text=True are set
+            assert kwargs.get("capture_output") is True, "Should capture stdout/stderr"
+            assert kwargs.get("text") is True, "Should decode output as text"
+
+            # Return successful JSON response
+            mock_result = Mock()
+            mock_result.returncode = 0
+            mock_result.stdout = '{"contextLength": 8192, "identifier": "custom-model"}'
+            mock_result.stderr = ""
+            return mock_result
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        # Test with typical LM Studio model
+        limit = _query_lmstudio_context_limit(
+            model_name="custom-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit == 8192, "Should return context length from SDK response"
+
+    def test_query_lmstudio_nodejs_not_found(self, monkeypatch):
+        """Verify graceful fallback when Node.js not installed.
+
+        When Node.js is not installed, subprocess.run will raise FileNotFoundError.
+        The function should catch this and return None (graceful fallback to registry).
+        """
+
+        def mock_run(*args, **kwargs):
+            raise FileNotFoundError("node: command not found")
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="custom-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit is None, "Should return None when Node.js not installed"
+
+    def test_query_lmstudio_sdk_not_installed(self, monkeypatch):
+        """Verify graceful fallback when @lmstudio/sdk not installed.
+
+        When the SDK npm package is not installed, Node.js will return non-zero
+        exit code with error message in stderr. The function should detect this
+        and return None.
+        """
+
+        def mock_run(*args, **kwargs):
+            mock_result = Mock()
+            mock_result.returncode = 1
+            mock_result.stdout = ""
+            mock_result.stderr = (
+                "Error: Cannot find module '@lmstudio/sdk'\nRequire stack:\n- /path/to/script.js"
+            )
+            return mock_result
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="custom-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit is None, "Should return None when SDK not installed"
+
+    def test_query_lmstudio_timeout(self, monkeypatch):
+        """Verify graceful fallback when subprocess times out.
+
+        When the Node.js process takes longer than 10 seconds (e.g., LM Studio
+        not responding), subprocess.TimeoutExpired should be raised. The function
+        should catch this and return None.
+        """
+
+        def mock_run(*args, **kwargs):
+            raise subprocess.TimeoutExpired(cmd=["node", "lmstudio_bridge.js"], timeout=10)
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="custom-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit is None, "Should return None on timeout"
+
+    def test_query_lmstudio_invalid_json(self, monkeypatch):
+        """Verify graceful fallback when response is invalid JSON.
+
+        When the subprocess returns malformed JSON (e.g., due to SDK error),
+        json.loads will raise ValueError/JSONDecodeError. The function should
+        catch this and return None.
+        """
+
+        def mock_run(*args, **kwargs):
+            mock_result = Mock()
+            mock_result.returncode = 0
+            mock_result.stdout = "This is not valid JSON"
+            mock_result.stderr = ""
+            return mock_result
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="custom-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit is None, "Should return None when JSON parsing fails"
+
+    def test_query_lmstudio_missing_context_length_field(self, monkeypatch):
+        """Verify graceful fallback when JSON lacks contextLength field.
+
+        When the SDK returns valid JSON but without the expected contextLength
+        field (e.g., error response), the function should return None.
+        """
+
+        def mock_run(*args, **kwargs):
+            mock_result = Mock()
+            mock_result.returncode = 0
+            mock_result.stdout = '{"identifier": "test-model", "error": "Model not found"}'
+            mock_result.stderr = ""
+            return mock_result
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="nonexistent-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit is None, "Should return None when contextLength field missing"
+
+    def test_query_lmstudio_null_context_length(self, monkeypatch):
+        """Verify graceful fallback when contextLength is null.
+
+        When the SDK returns contextLength: null (model couldn't be loaded),
+        the function should return None for registry fallback.
+        """
+
+        def mock_run(*args, **kwargs):
+            mock_result = Mock()
+            mock_result.returncode = 0
+            mock_result.stdout = '{"contextLength": null, "identifier": "test-model"}'
+            mock_result.stderr = ""
+            return mock_result
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="test-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit is None, "Should return None when contextLength is null"
+
+    def test_query_lmstudio_zero_context_length(self, monkeypatch):
+        """Verify graceful fallback when contextLength is zero.
+
+        When the SDK returns contextLength: 0 (invalid value), the function
+        should return None to trigger registry fallback.
+        """
+
+        def mock_run(*args, **kwargs):
+            mock_result = Mock()
+            mock_result.returncode = 0
+            mock_result.stdout = '{"contextLength": 0, "identifier": "test-model"}'
+            mock_result.stderr = ""
+            return mock_result
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="test-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit is None, "Should return None when contextLength is zero"
+
+    def test_query_lmstudio_with_custom_port(self, monkeypatch):
+        """Verify SDK query works with non-default WebSocket port.
+
+        LM Studio can run on custom ports. The function should pass the
+        provided base_url to the Node.js subprocess.
+        """
+
+        def mock_run(*args, **kwargs):
+            # Verify the base_url argument is passed correctly
+            command = args[0] if args else kwargs.get("args", [])
+            assert "ws://localhost:8080" in " ".join(command), (
+                "Should pass custom port to subprocess"
+            )
+
+            mock_result = Mock()
+            mock_result.returncode = 0
+            mock_result.stdout = '{"contextLength": 4096, "identifier": "custom-model"}'
+            mock_result.stderr = ""
+            return mock_result
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="custom-model", base_url="ws://localhost:8080"
+        )
+
+        assert limit == 4096, "Should work with custom WebSocket port"
+
+    @pytest.mark.parametrize(
+        "context_length,expected",
+        [
+            (512, 512),  # Small context
+            (2048, 2048),  # Common context
+            (8192, 8192),  # Large context
+            (32768, 32768),  # Very large context
+        ],
+    )
+    def test_query_lmstudio_various_context_lengths(self, monkeypatch, context_length, expected):
+        """Verify SDK query handles various context length values.
+
+        Different models have different context lengths. The function should
+        correctly parse and return any positive integer value.
+        """
+
+        def mock_run(*args, **kwargs):
+            mock_result = Mock()
+            mock_result.returncode = 0
+            mock_result.stdout = f'{{"contextLength": {context_length}, "identifier": "test"}}'
+            mock_result.stderr = ""
+            return mock_result
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        limit = _query_lmstudio_context_limit(
+            model_name="test-model", base_url="ws://localhost:1234"
+        )
+
+        assert limit == expected, f"Should return {expected} for context length {context_length}"
+
+    def test_query_lmstudio_logs_at_debug_level(self, monkeypatch, caplog):
+        """Verify errors are logged at DEBUG level, not WARNING/ERROR.
+
+        Following the graceful fallback pattern from Ollama implementation,
+        errors should be logged at debug level to avoid alarming users when
+        fallback to registry works fine.
+        """
+        import logging
+
+        caplog.set_level(logging.DEBUG, logger="leann.embedding_compute")
+
+        def mock_run(*args, **kwargs):
+            raise FileNotFoundError("node: command not found")
+
+        monkeypatch.setattr("subprocess.run", mock_run)
+
+        _query_lmstudio_context_limit(model_name="test-model", base_url="ws://localhost:1234")
+
+        # Check that debug logging occurred (not warning/error)
+        debug_logs = [record for record in caplog.records if record.levelname == "DEBUG"]
+        assert len(debug_logs) > 0, "Should log error at DEBUG level"
+
+        # Verify no WARNING or ERROR logs
+        warning_or_error_logs = [
+            record for record in caplog.records if record.levelname in ["WARNING", "ERROR"]
+        ]
+        assert len(warning_or_error_logs) == 0, (
+            "Should not log at WARNING/ERROR level for expected failures"
+        )

tests/test_prompt_template_e2e.py

@@ -0,0 +1,400 @@
+"""End-to-end integration tests for prompt template and token limit features.
+
+These tests verify real-world functionality with live services:
+- OpenAI-compatible APIs (OpenAI, LM Studio) with prompt template support
+- Ollama with dynamic token limit detection
+- Hybrid token limit discovery mechanism
+
+Run with: pytest tests/test_prompt_template_e2e.py -v -s
+Skip if services unavailable: pytest tests/test_prompt_template_e2e.py -m "not integration"
+
+Prerequisites:
+1. LM Studio running with embedding model: http://localhost:1234
+2. [Optional] Ollama running: ollama serve
+3. [Optional] Ollama model: ollama pull nomic-embed-text
+4. [Optional] Node.js + @lmstudio/sdk for context length detection
+"""
+
+import logging
+import socket
+
+import numpy as np
+import pytest
+import requests
+from leann.embedding_compute import (
+    compute_embeddings_ollama,
+    compute_embeddings_openai,
+    get_model_token_limit,
+)
+
+# Test markers for conditional execution
+pytestmark = pytest.mark.integration
+
+logger = logging.getLogger(__name__)
+
+
+def check_service_available(host: str, port: int, timeout: float = 2.0) -> bool:
+    """Check if a service is available on the given host:port."""
+    try:
+        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        sock.settimeout(timeout)
+        result = sock.connect_ex((host, port))
+        sock.close()
+        return result == 0
+    except Exception:
+        return False
+
+
+def check_ollama_available() -> bool:
+    """Check if Ollama service is available."""
+    if not check_service_available("localhost", 11434):
+        return False
+    try:
+        response = requests.get("http://localhost:11434/api/tags", timeout=2.0)
+        return response.status_code == 200
+    except Exception:
+        return False
+
+
+def check_lmstudio_available() -> bool:
+    """Check if LM Studio service is available."""
+    if not check_service_available("localhost", 1234):
+        return False
+    try:
+        response = requests.get("http://localhost:1234/v1/models", timeout=2.0)
+        return response.status_code == 200
+    except Exception:
+        return False
+
+
+def get_lmstudio_first_model() -> str:
+    """Get the first available model from LM Studio."""
+    try:
+        response = requests.get("http://localhost:1234/v1/models", timeout=5.0)
+        data = response.json()
+        models = data.get("data", [])
+        if models:
+            return models[0]["id"]
+    except Exception:
+        pass
+    return None
+
+
+class TestPromptTemplateOpenAI:
+    """End-to-end tests for prompt template with OpenAI-compatible APIs (LM Studio)."""
+
+    @pytest.mark.skipif(
+        not check_lmstudio_available(), reason="LM Studio service not available on localhost:1234"
+    )
+    def test_lmstudio_embedding_with_prompt_template(self):
+        """Test prompt templates with LM Studio using OpenAI-compatible API."""
+        model_name = get_lmstudio_first_model()
+        if not model_name:
+            pytest.skip("No models loaded in LM Studio")
+
+        texts = ["artificial intelligence", "machine learning"]
+        prompt_template = "search_query: "
+
+        # Get embeddings with prompt template via provider_options
+        provider_options = {"prompt_template": prompt_template}
+        embeddings = compute_embeddings_openai(
+            texts=texts,
+            model_name=model_name,
+            base_url="http://localhost:1234/v1",
+            api_key="lm-studio",  # LM Studio doesn't require real key
+            provider_options=provider_options,
+        )
+
+        assert embeddings is not None
+        assert len(embeddings) == 2
+        assert all(isinstance(emb, np.ndarray) for emb in embeddings)
+        assert all(len(emb) > 0 for emb in embeddings)
+
+        logger.info(
+            f"✓ LM Studio embeddings with prompt template: {len(embeddings)} vectors, {len(embeddings[0])} dimensions"
+        )
+
+    @pytest.mark.skipif(not check_lmstudio_available(), reason="LM Studio service not available")
+    def test_lmstudio_prompt_template_affects_embeddings(self):
+        """Verify that prompt templates actually change embedding values."""
+        model_name = get_lmstudio_first_model()
+        if not model_name:
+            pytest.skip("No models loaded in LM Studio")
+
+        text = "machine learning"
+        base_url = "http://localhost:1234/v1"
+        api_key = "lm-studio"
+
+        # Get embeddings without template
+        embeddings_no_template = compute_embeddings_openai(
+            texts=[text],
+            model_name=model_name,
+            base_url=base_url,
+            api_key=api_key,
+            provider_options={},
+        )
+
+        # Get embeddings with template
+        embeddings_with_template = compute_embeddings_openai(
+            texts=[text],
+            model_name=model_name,
+            base_url=base_url,
+            api_key=api_key,
+            provider_options={"prompt_template": "search_query: "},
+        )
+
+        # Embeddings should be different when template is applied
+        assert not np.allclose(embeddings_no_template[0], embeddings_with_template[0])
+
+        logger.info("✓ Prompt template changes embedding values as expected")
+
+
+class TestPromptTemplateOllama:
+    """End-to-end tests for prompt template with Ollama."""
+
+    @pytest.mark.skipif(
+        not check_ollama_available(), reason="Ollama service not available on localhost:11434"
+    )
+    def test_ollama_embedding_with_prompt_template(self):
+        """Test prompt templates with Ollama using any available embedding model."""
+        # Get any available embedding model
+        try:
+            response = requests.get("http://localhost:11434/api/tags", timeout=2.0)
+            models = response.json().get("models", [])
+
+            embedding_models = []
+            for model in models:
+                name = model["name"]
+                base_name = name.split(":")[0]
+                if any(emb in base_name for emb in ["embed", "bge", "minilm", "e5", "nomic"]):
+                    embedding_models.append(name)
+
+            if not embedding_models:
+                pytest.skip("No embedding models available in Ollama")
+
+            model_name = embedding_models[0]
+
+            texts = ["artificial intelligence", "machine learning"]
+            prompt_template = "search_query: "
+
+            # Get embeddings with prompt template via provider_options
+            provider_options = {"prompt_template": prompt_template}
+            embeddings = compute_embeddings_ollama(
+                texts=texts,
+                model_name=model_name,
+                is_build=False,
+                host="http://localhost:11434",
+                provider_options=provider_options,
+            )
+
+            assert embeddings is not None
+            assert len(embeddings) == 2
+            assert all(isinstance(emb, np.ndarray) for emb in embeddings)
+            assert all(len(emb) > 0 for emb in embeddings)
+
+            logger.info(
+                f"✓ Ollama embeddings with prompt template: {len(embeddings)} vectors, {len(embeddings[0])} dimensions"
+            )
+
+        except Exception as e:
+            pytest.skip(f"Could not test Ollama prompt template: {e}")
+
+    @pytest.mark.skipif(not check_ollama_available(), reason="Ollama service not available")
+    def test_ollama_prompt_template_affects_embeddings(self):
+        """Verify that prompt templates actually change embedding values with Ollama."""
+        # Get any available embedding model
+        try:
+            response = requests.get("http://localhost:11434/api/tags", timeout=2.0)
+            models = response.json().get("models", [])
+
+            embedding_models = []
+            for model in models:
+                name = model["name"]
+                base_name = name.split(":")[0]
+                if any(emb in base_name for emb in ["embed", "bge", "minilm", "e5", "nomic"]):
+                    embedding_models.append(name)
+
+            if not embedding_models:
+                pytest.skip("No embedding models available in Ollama")
+
+            model_name = embedding_models[0]
+            text = "machine learning"
+            host = "http://localhost:11434"
+
+            # Get embeddings without template
+            embeddings_no_template = compute_embeddings_ollama(
+                texts=[text], model_name=model_name, is_build=False, host=host, provider_options={}
+            )
+
+            # Get embeddings with template
+            embeddings_with_template = compute_embeddings_ollama(
+                texts=[text],
+                model_name=model_name,
+                is_build=False,
+                host=host,
+                provider_options={"prompt_template": "search_query: "},
+            )
+
+            # Embeddings should be different when template is applied
+            assert not np.allclose(embeddings_no_template[0], embeddings_with_template[0])
+
+            logger.info("✓ Ollama prompt template changes embedding values as expected")
+
+        except Exception as e:
+            pytest.skip(f"Could not test Ollama prompt template: {e}")
+
+
+class TestLMStudioSDK:
+    """End-to-end tests for LM Studio SDK integration."""
+
+    @pytest.mark.skipif(not check_lmstudio_available(), reason="LM Studio service not available")
+    def test_lmstudio_model_listing(self):
+        """Test that we can list models from LM Studio."""
+        try:
+            response = requests.get("http://localhost:1234/v1/models", timeout=5.0)
+            assert response.status_code == 200
+
+            data = response.json()
+            assert "data" in data
+
+            models = data["data"]
+            logger.info(f"✓ LM Studio models available: {len(models)}")
+
+            if models:
+                logger.info(f"  First model: {models[0].get('id', 'unknown')}")
+        except Exception as e:
+            pytest.skip(f"LM Studio API error: {e}")
+
+    @pytest.mark.skipif(not check_lmstudio_available(), reason="LM Studio service not available")
+    def test_lmstudio_sdk_context_length_detection(self):
+        """Test context length detection via LM Studio SDK bridge (requires Node.js + SDK)."""
+        model_name = get_lmstudio_first_model()
+        if not model_name:
+            pytest.skip("No models loaded in LM Studio")
+
+        try:
+            from leann.embedding_compute import _query_lmstudio_context_limit
+
+            # SDK requires WebSocket URL (ws://)
+            context_length = _query_lmstudio_context_limit(
+                model_name=model_name, base_url="ws://localhost:1234"
+            )
+
+            if context_length is None:
+                logger.warning(
+                    "⚠ LM Studio SDK bridge returned None (Node.js or SDK may not be available)"
+                )
+                pytest.skip("Node.js or @lmstudio/sdk not available - SDK bridge unavailable")
+            else:
+                assert context_length > 0
+                logger.info(
+                    f"✓ LM Studio context length detected via SDK: {context_length} for {model_name}"
+                )
+
+        except ImportError:
+            pytest.skip("_query_lmstudio_context_limit not implemented yet")
+        except Exception as e:
+            logger.error(f"LM Studio SDK test error: {e}")
+            raise
+
+
+class TestOllamaTokenLimit:
+    """End-to-end tests for Ollama token limit discovery."""
+
+    @pytest.mark.skipif(not check_ollama_available(), reason="Ollama service not available")
+    def test_ollama_token_limit_detection(self):
+        """Test dynamic token limit detection from Ollama /api/show endpoint."""
+        # Get any available embedding model
+        try:
+            response = requests.get("http://localhost:11434/api/tags", timeout=2.0)
+            models = response.json().get("models", [])
+
+            embedding_models = []
+            for model in models:
+                name = model["name"]
+                base_name = name.split(":")[0]
+                if any(emb in base_name for emb in ["embed", "bge", "minilm", "e5", "nomic"]):
+                    embedding_models.append(name)
+
+            if not embedding_models:
+                pytest.skip("No embedding models available in Ollama")
+
+            test_model = embedding_models[0]
+
+            # Test token limit detection
+            limit = get_model_token_limit(model_name=test_model, base_url="http://localhost:11434")
+
+            assert limit > 0
+            logger.info(f"✓ Ollama token limit detected: {limit} for {test_model}")
+
+        except Exception as e:
+            pytest.skip(f"Could not test Ollama token detection: {e}")
+
+
+class TestHybridTokenLimit:
+    """End-to-end tests for hybrid token limit discovery mechanism."""
+
+    def test_hybrid_discovery_registry_fallback(self):
+        """Test fallback to static registry for known OpenAI models."""
+        # Use a known OpenAI model (should be in registry)
+        limit = get_model_token_limit(
+            model_name="text-embedding-3-small",
+            base_url="http://fake-server:9999",  # Fake URL to force registry lookup
+        )
+
+        # text-embedding-3-small should have 8192 in registry
+        assert limit == 8192
+        logger.info(f"✓ Hybrid discovery (registry fallback): {limit} tokens")
+
+    def test_hybrid_discovery_default_fallback(self):
+        """Test fallback to safe default for completely unknown models."""
+        limit = get_model_token_limit(
+            model_name="completely-unknown-model-xyz-12345",
+            base_url="http://fake-server:9999",
+            default=512,
+        )
+
+        # Should get the specified default
+        assert limit == 512
+        logger.info(f"✓ Hybrid discovery (default fallback): {limit} tokens")
+
+    @pytest.mark.skipif(not check_ollama_available(), reason="Ollama service not available")
+    def test_hybrid_discovery_ollama_dynamic_first(self):
+        """Test that Ollama models use dynamic discovery first."""
+        # Get any available embedding model
+        try:
+            response = requests.get("http://localhost:11434/api/tags", timeout=2.0)
+            models = response.json().get("models", [])
+
+            embedding_models = []
+            for model in models:
+                name = model["name"]
+                base_name = name.split(":")[0]
+                if any(emb in base_name for emb in ["embed", "bge", "minilm", "e5", "nomic"]):
+                    embedding_models.append(name)
+
+            if not embedding_models:
+                pytest.skip("No embedding models available in Ollama")
+
+            test_model = embedding_models[0]
+
+            # Should query Ollama /api/show dynamically
+            limit = get_model_token_limit(model_name=test_model, base_url="http://localhost:11434")
+
+            assert limit > 0
+            logger.info(f"✓ Hybrid discovery (Ollama dynamic): {limit} tokens for {test_model}")
+
+        except Exception as e:
+            pytest.skip(f"Could not test hybrid Ollama discovery: {e}")
+
+
+if __name__ == "__main__":
+    print("\n" + "=" * 70)
+    print("INTEGRATION TEST SUITE - Real Service Testing")
+    print("=" * 70)
+    print("\nThese tests require live services:")
+    print("  • LM Studio: http://localhost:1234 (with embedding model loaded)")
+    print("  • [Optional] Ollama: http://localhost:11434")
+    print("  • [Optional] Node.js + @lmstudio/sdk for SDK bridge tests")
+    print("\nRun with: pytest tests/test_prompt_template_e2e.py -v -s")
+    print("=" * 70 + "\n")

tests/test_prompt_template_persistence.py

@@ -0,0 +1,808 @@
+"""
+Integration tests for prompt template metadata persistence and reuse.
+
+These tests verify the complete lifecycle of prompt template persistence:
+1. Template is saved to .meta.json during index build
+2. Template is automatically loaded during search operations
+3. Template can be overridden with explicit flag during search
+4. Template is reused during chat/ask operations
+
+These are integration tests that:
+- Use real file system with temporary directories
+- Run actual build and search operations
+- Inspect .meta.json file contents directly
+- Mock embedding servers to avoid external dependencies
+- Use small test codebases for fast execution
+
+Expected to FAIL in Red Phase because metadata persistence verification is not yet implemented.
+"""
+
+import json
+import tempfile
+from pathlib import Path
+from unittest.mock import Mock, patch
+
+import numpy as np
+import pytest
+from leann.api import LeannBuilder, LeannSearcher
+
+
+class TestPromptTemplateMetadataPersistence:
+    """Tests for prompt template storage in .meta.json during build."""
+
+    @pytest.fixture
+    def temp_index_dir(self):
+        """Create temporary directory for test indexes."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            yield Path(tmpdir)
+
+    @pytest.fixture
+    def mock_embeddings(self):
+        """Mock compute_embeddings to return dummy embeddings."""
+        with patch("leann.api.compute_embeddings") as mock_compute:
+            # Return dummy embeddings as numpy array
+            mock_compute.return_value = np.array([[0.1, 0.2, 0.3]], dtype=np.float32)
+            yield mock_compute
+
+    def test_prompt_template_saved_to_metadata(self, temp_index_dir, mock_embeddings):
+        """
+        Verify that when build is run with embedding_options containing prompt_template,
+        the template value is saved to .meta.json file.
+
+        This is the core persistence requirement - templates must be saved to allow
+        reuse in subsequent search operations without re-specifying the flag.
+
+        Expected failure: .meta.json exists but doesn't contain embedding_options
+        with prompt_template, or the value is not persisted correctly.
+        """
+        # Setup test data
+        index_path = temp_index_dir / "test_index.leann"
+        template = "search_document: "
+
+        # Build index with prompt template in embedding_options
+        builder = LeannBuilder(
+            backend_name="hnsw",
+            embedding_model="text-embedding-3-small",
+            embedding_mode="openai",
+            embedding_options={"prompt_template": template},
+        )
+
+        # Add a simple document
+        builder.add_text("This is a test document for indexing")
+
+        # Build the index
+        builder.build_index(str(index_path))
+
+        # Verify .meta.json was created and contains the template
+        meta_path = temp_index_dir / "test_index.leann.meta.json"
+        assert meta_path.exists(), ".meta.json file should be created during build"
+
+        # Read and parse metadata
+        with open(meta_path, encoding="utf-8") as f:
+            meta_data = json.load(f)
+
+        # Verify embedding_options exists in metadata
+        assert "embedding_options" in meta_data, (
+            "embedding_options should be saved to .meta.json when provided"
+        )
+
+        # Verify prompt_template is in embedding_options
+        embedding_options = meta_data["embedding_options"]
+        assert "prompt_template" in embedding_options, (
+            "prompt_template should be saved within embedding_options"
+        )
+
+        # Verify the template value matches what we provided
+        assert embedding_options["prompt_template"] == template, (
+            f"Template should be '{template}', got '{embedding_options.get('prompt_template')}'"
+        )
+
+    def test_prompt_template_absent_when_not_provided(self, temp_index_dir, mock_embeddings):
+        """
+        Verify that when no prompt template is provided during build,
+        .meta.json either doesn't have embedding_options or prompt_template key.
+
+        This ensures clean metadata without unnecessary keys when features aren't used.
+
+        Expected behavior: Build succeeds, .meta.json doesn't contain prompt_template.
+        """
+        index_path = temp_index_dir / "test_no_template.leann"
+
+        # Build index WITHOUT prompt template
+        builder = LeannBuilder(
+            backend_name="hnsw",
+            embedding_model="text-embedding-3-small",
+            embedding_mode="openai",
+            # No embedding_options provided
+        )
+
+        builder.add_text("Document without template")
+        builder.build_index(str(index_path))
+
+        # Verify metadata
+        meta_path = temp_index_dir / "test_no_template.leann.meta.json"
+        assert meta_path.exists()
+
+        with open(meta_path, encoding="utf-8") as f:
+            meta_data = json.load(f)
+
+        # If embedding_options exists, it should not contain prompt_template
+        if "embedding_options" in meta_data:
+            embedding_options = meta_data["embedding_options"]
+            assert "prompt_template" not in embedding_options, (
+                "prompt_template should not be in metadata when not provided"
+            )
+
+
+class TestPromptTemplateAutoLoadOnSearch:
+    """Tests for automatic loading of prompt template during search operations.
+
+    NOTE: Over-mocked test removed (test_prompt_template_auto_loaded_on_search).
+    This functionality is now comprehensively tested by TestQueryPromptTemplateAutoLoad
+    which uses simpler mocking and doesn't hang.
+    """
+
+    @pytest.fixture
+    def temp_index_dir(self):
+        """Create temporary directory for test indexes."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            yield Path(tmpdir)
+
+    @pytest.fixture
+    def mock_embeddings(self):
+        """Mock compute_embeddings to capture calls and return dummy embeddings."""
+        with patch("leann.api.compute_embeddings") as mock_compute:
+            mock_compute.return_value = np.array([[0.1, 0.2, 0.3]], dtype=np.float32)
+            yield mock_compute
+
+    def test_search_without_template_in_metadata(self, temp_index_dir, mock_embeddings):
+        """
+        Verify that searching an index built WITHOUT a prompt template
+        works correctly (backward compatibility).
+
+        The searcher should handle missing prompt_template gracefully.
+
+        Expected behavior: Search succeeds, no template is used.
+        """
+        # Build index without template
+        index_path = temp_index_dir / "no_template.leann"
+
+        builder = LeannBuilder(
+            backend_name="hnsw",
+            embedding_model="text-embedding-3-small",
+            embedding_mode="openai",
+        )
+        builder.add_text("Document without template")
+        builder.build_index(str(index_path))
+
+        # Reset mocks
+        mock_embeddings.reset_mock()
+
+        # Create searcher and search
+        searcher = LeannSearcher(index_path=str(index_path))
+
+        # Verify no template in embedding_options
+        assert "prompt_template" not in searcher.embedding_options, (
+            "Searcher should not have prompt_template when not in metadata"
+        )
+
+
+class TestQueryPromptTemplateAutoLoad:
+    """Tests for automatic loading of separate query_prompt_template during search (R2).
+
+    These tests verify the new two-template system where:
+    - build_prompt_template: Applied during index building
+    - query_prompt_template: Applied during search operations
+
+    Expected to FAIL in Red Phase (R2) because query template extraction
+    and application is not yet implemented in LeannSearcher.search().
+    """
+
+    @pytest.fixture
+    def temp_index_dir(self):
+        """Create temporary directory for test indexes."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            yield Path(tmpdir)
+
+    @pytest.fixture
+    def mock_compute_embeddings(self):
+        """Mock compute_embeddings to capture calls and return dummy embeddings."""
+        with patch("leann.embedding_compute.compute_embeddings") as mock_compute:
+            mock_compute.return_value = np.array([[0.1, 0.2, 0.3]], dtype=np.float32)
+            yield mock_compute
+
+    def test_search_auto_loads_query_template(self, temp_index_dir, mock_compute_embeddings):
+        """
+        Verify that search() automatically loads and applies query_prompt_template from .meta.json.
+
+        Given: Index built with separate build_prompt_template and query_prompt_template
+        When: LeannSearcher.search("my query") is called
+        Then: Query embedding is computed with "query: my query" (query template applied)
+
+        This is the core R2 requirement - query templates must be auto-loaded and applied
+        during search without user intervention.
+
+        Expected failure: compute_embeddings called with raw "my query" instead of
+        "query: my query" because query template extraction is not implemented.
+        """
+        # Setup: Build index with separate templates in new format
+        index_path = temp_index_dir / "query_template.leann"
+
+        builder = LeannBuilder(
+            backend_name="hnsw",
+            embedding_model="text-embedding-3-small",
+            embedding_mode="openai",
+            embedding_options={
+                "build_prompt_template": "doc: ",
+                "query_prompt_template": "query: ",
+            },
+        )
+        builder.add_text("Test document")
+        builder.build_index(str(index_path))
+
+        # Reset mock to ignore build calls
+        mock_compute_embeddings.reset_mock()
+
+        # Act: Search with query
+        searcher = LeannSearcher(index_path=str(index_path))
+
+        # Mock the backend search to avoid actual search
+        with patch.object(searcher.backend_impl, "search") as mock_backend_search:
+            mock_backend_search.return_value = {
+                "labels": [["test_id_0"]],  # IDs (nested list for batch support)
+                "distances": [[0.9]],  # Distances (nested list for batch support)
+            }
+
+            searcher.search("my query", top_k=1, recompute_embeddings=False)
+
+        # Assert: compute_embeddings was called with query template applied
+        assert mock_compute_embeddings.called, "compute_embeddings should be called during search"
+
+        # Get the actual text passed to compute_embeddings
+        call_args = mock_compute_embeddings.call_args
+        texts_arg = call_args[0][0]  # First positional arg (list of texts)
+
+        assert len(texts_arg) == 1, "Should compute embedding for one query"
+        assert texts_arg[0] == "query: my query", (
+            f"Query template should be applied: expected 'query: my query', got '{texts_arg[0]}'"
+        )
+
+    def test_search_backward_compat_single_template(self, temp_index_dir, mock_compute_embeddings):
+        """
+        Verify backward compatibility with old single prompt_template format.
+
+        Given: Index with old format (single prompt_template, no query_prompt_template)
+        When: LeannSearcher.search("my query") is called
+        Then: Query embedding computed with "doc: my query" (old template applied)
+
+        This ensures indexes built with the old single-template system continue
+        to work correctly with the new search implementation.
+
+        Expected failure: Old template not recognized/applied because backward
+        compatibility logic is not implemented.
+        """
+        # Setup: Build index with old single-template format
+        index_path = temp_index_dir / "old_template.leann"
+
+        builder = LeannBuilder(
+            backend_name="hnsw",
+            embedding_model="text-embedding-3-small",
+            embedding_mode="openai",
+            embedding_options={"prompt_template": "doc: "},  # Old format
+        )
+        builder.add_text("Test document")
+        builder.build_index(str(index_path))
+
+        # Reset mock
+        mock_compute_embeddings.reset_mock()
+
+        # Act: Search
+        searcher = LeannSearcher(index_path=str(index_path))
+
+        with patch.object(searcher.backend_impl, "search") as mock_backend_search:
+            mock_backend_search.return_value = {"labels": [["test_id_0"]], "distances": [[0.9]]}
+
+            searcher.search("my query", top_k=1, recompute_embeddings=False)
+
+        # Assert: Old template was applied
+        call_args = mock_compute_embeddings.call_args
+        texts_arg = call_args[0][0]
+
+        assert texts_arg[0] == "doc: my query", (
+            f"Old prompt_template should be applied for backward compatibility: "
+            f"expected 'doc: my query', got '{texts_arg[0]}'"
+        )
+
+    def test_search_backward_compat_no_template(self, temp_index_dir, mock_compute_embeddings):
+        """
+        Verify backward compatibility when no template is present in .meta.json.
+
+        Given: Index with no template in .meta.json (very old indexes)
+        When: LeannSearcher.search("my query") is called
+        Then: Query embedding computed with "my query" (no template, raw query)
+
+        This ensures the most basic backward compatibility - indexes without
+        any template support continue to work as before.
+
+        Expected failure: May fail if default template is incorrectly applied,
+        or if missing template causes error.
+        """
+        # Setup: Build index without any template
+        index_path = temp_index_dir / "no_template.leann"
+
+        builder = LeannBuilder(
+            backend_name="hnsw",
+            embedding_model="text-embedding-3-small",
+            embedding_mode="openai",
+            # No embedding_options at all
+        )
+        builder.add_text("Test document")
+        builder.build_index(str(index_path))
+
+        # Reset mock
+        mock_compute_embeddings.reset_mock()
+
+        # Act: Search
+        searcher = LeannSearcher(index_path=str(index_path))
+
+        with patch.object(searcher.backend_impl, "search") as mock_backend_search:
+            mock_backend_search.return_value = {"labels": [["test_id_0"]], "distances": [[0.9]]}
+
+            searcher.search("my query", top_k=1, recompute_embeddings=False)
+
+        # Assert: No template applied (raw query)
+        call_args = mock_compute_embeddings.call_args
+        texts_arg = call_args[0][0]
+
+        assert texts_arg[0] == "my query", (
+            f"No template should be applied when missing from metadata: "
+            f"expected 'my query', got '{texts_arg[0]}'"
+        )
+
+    def test_search_override_via_provider_options(self, temp_index_dir, mock_compute_embeddings):
+        """
+        Verify that explicit provider_options can override stored query template.
+
+        Given: Index with query_prompt_template: "query: "
+        When: search() called with provider_options={"prompt_template": "override: "}
+        Then: Query embedding computed with "override: test" (override takes precedence)
+
+        This enables users to experiment with different query templates without
+        rebuilding the index, or to handle special query types differently.
+
+        Expected failure: provider_options parameter is accepted via **kwargs but
+        not used. Query embedding computed with raw "test" instead of "override: test"
+        because override logic is not implemented.
+        """
+        # Setup: Build index with query template
+        index_path = temp_index_dir / "override_template.leann"
+
+        builder = LeannBuilder(
+            backend_name="hnsw",
+            embedding_model="text-embedding-3-small",
+            embedding_mode="openai",
+            embedding_options={
+                "build_prompt_template": "doc: ",
+                "query_prompt_template": "query: ",
+            },
+        )
+        builder.add_text("Test document")
+        builder.build_index(str(index_path))
+
+        # Reset mock
+        mock_compute_embeddings.reset_mock()
+
+        # Act: Search with override
+        searcher = LeannSearcher(index_path=str(index_path))
+
+        with patch.object(searcher.backend_impl, "search") as mock_backend_search:
+            mock_backend_search.return_value = {"labels": [["test_id_0"]], "distances": [[0.9]]}
+
+            # This should accept provider_options parameter
+            searcher.search(
+                "test",
+                top_k=1,
+                recompute_embeddings=False,
+                provider_options={"prompt_template": "override: "},
+            )
+
+        # Assert: Override template was applied
+        call_args = mock_compute_embeddings.call_args
+        texts_arg = call_args[0][0]
+
+        assert texts_arg[0] == "override: test", (
+            f"Override template should take precedence: "
+            f"expected 'override: test', got '{texts_arg[0]}'"
+        )
+
+
+class TestPromptTemplateReuseInChat:
+    """Tests for prompt template reuse in chat/ask operations."""
+
+    @pytest.fixture
+    def temp_index_dir(self):
+        """Create temporary directory for test indexes."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            yield Path(tmpdir)
+
+    @pytest.fixture
+    def mock_embeddings(self):
+        """Mock compute_embeddings to return dummy embeddings."""
+        with patch("leann.api.compute_embeddings") as mock_compute:
+            mock_compute.return_value = np.array([[0.1, 0.2, 0.3]], dtype=np.float32)
+            yield mock_compute
+
+    @pytest.fixture
+    def mock_embedding_server_manager(self):
+        """Mock EmbeddingServerManager for chat tests."""
+        with patch("leann.searcher_base.EmbeddingServerManager") as mock_manager_class:
+            mock_manager = Mock()
+            mock_manager.start_server.return_value = (True, 5557)
+            mock_manager_class.return_value = mock_manager
+            yield mock_manager
+
+    @pytest.fixture
+    def index_with_template(self, temp_index_dir, mock_embeddings):
+        """Build an index with a prompt template."""
+        index_path = temp_index_dir / "chat_template_index.leann"
+        template = "document_query: "
+
+        builder = LeannBuilder(
+            backend_name="hnsw",
+            embedding_model="text-embedding-3-small",
+            embedding_mode="openai",
+            embedding_options={"prompt_template": template},
+        )
+
+        builder.add_text("Test document for chat")
+        builder.build_index(str(index_path))
+
+        return str(index_path), template
+
+
+class TestPromptTemplateIntegrationWithEmbeddingModes:
+    """Tests for prompt template compatibility with different embedding modes."""
+
+    @pytest.fixture
+    def temp_index_dir(self):
+        """Create temporary directory for test indexes."""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            yield Path(tmpdir)
+
+    @pytest.mark.parametrize(
+        "mode,model,template,filename_prefix",
+        [
+            (
+                "openai",
+                "text-embedding-3-small",
+                "Represent this for searching: ",
+                "openai_template",
+            ),
+            ("ollama", "nomic-embed-text", "search_query: ", "ollama_template"),
+            ("sentence-transformers", "facebook/contriever", "query: ", "st_template"),
+        ],
+    )
+    def test_prompt_template_metadata_with_embedding_modes(
+        self, temp_index_dir, mode, model, template, filename_prefix
+    ):
+        """Verify prompt template is saved correctly across different embedding modes.
+
+        Tests that prompt templates are persisted to .meta.json for:
+        - OpenAI mode (primary use case)
+        - Ollama mode (also supports templates)
+        - Sentence-transformers mode (saved for forward compatibility)
+
+        Expected behavior: Template is saved to .meta.json regardless of mode.
+        """
+        with patch("leann.api.compute_embeddings") as mock_compute:
+            mock_compute.return_value = np.array([[0.1, 0.2, 0.3]], dtype=np.float32)
+
+            index_path = temp_index_dir / f"{filename_prefix}.leann"
+
+            builder = LeannBuilder(
+                backend_name="hnsw",
+                embedding_model=model,
+                embedding_mode=mode,
+                embedding_options={"prompt_template": template},
+            )
+
+            builder.add_text(f"{mode.capitalize()} test document")
+            builder.build_index(str(index_path))
+
+            # Verify metadata
+            meta_path = temp_index_dir / f"{filename_prefix}.leann.meta.json"
+            with open(meta_path, encoding="utf-8") as f:
+                meta_data = json.load(f)
+
+            assert meta_data["embedding_mode"] == mode
+            # Template should be saved for all modes (even if not used by some)
+            if "embedding_options" in meta_data:
+                assert meta_data["embedding_options"]["prompt_template"] == template
+
+
+class TestQueryTemplateApplicationInComputeEmbedding:
+    """Tests for query template application in compute_query_embedding() (Bug Fix).
+
+    These tests verify that query templates are applied consistently in BOTH
+    code paths (server and fallback) when computing query embeddings.
+
+    This addresses the bug where query templates were only applied in the
+    fallback path, not when using the embedding server (the default path).
+
+    Bug Context:
+    - Issue: Query templates were stored in metadata but only applied during
+      fallback (direct) computation, not when using embedding server
+    - Fix: Move template application to BEFORE any computation path in
+      compute_query_embedding() (searcher_base.py:107-110)
+    - Impact: Critical for models like EmbeddingGemma that require task-specific
+      templates for optimal performance
+
+    These tests ensure the fix works correctly and prevent regression.
+    """
+
+    @pytest.fixture
+    def temp_index_with_template(self):
+        """Create a temporary index with query template in metadata"""
+        with tempfile.TemporaryDirectory() as tmpdir:
+            index_dir = Path(tmpdir)
+            index_file = index_dir / "test.leann"
+            meta_file = index_dir / "test.leann.meta.json"
+
+            # Create minimal metadata with query template
+            metadata = {
+                "version": "1.0",
+                "backend_name": "hnsw",
+                "embedding_model": "text-embedding-embeddinggemma-300m-qat",
+                "dimensions": 768,
+                "embedding_mode": "openai",
+                "backend_kwargs": {
+                    "graph_degree": 32,
+                    "complexity": 64,
+                    "distance_metric": "cosine",
+                },
+                "embedding_options": {
+                    "base_url": "http://localhost:1234/v1",
+                    "api_key": "test-key",
+                    "build_prompt_template": "title: none | text: ",
+                    "query_prompt_template": "task: search result | query: ",
+                },
+            }
+
+            meta_file.write_text(json.dumps(metadata, indent=2))
+
+            # Create minimal HNSW index file (empty is okay for this test)
+            index_file.write_bytes(b"")
+
+            yield str(index_file)
+
+    def test_query_template_applied_in_fallback_path(self, temp_index_with_template):
+        """Test that query template is applied when using fallback (direct) path"""
+        from leann.searcher_base import BaseSearcher
+
+        # Create a concrete implementation for testing
+        class TestSearcher(BaseSearcher):
+            def search(self, query_vectors, top_k, complexity, beam_width=1, **kwargs):
+                return {"labels": [], "distances": []}
+
+        searcher = object.__new__(TestSearcher)
+        searcher.index_path = Path(temp_index_with_template)
+        searcher.index_dir = searcher.index_path.parent
+
+        # Load metadata
+        meta_file = searcher.index_dir / f"{searcher.index_path.name}.meta.json"
+        with open(meta_file) as f:
+            searcher.meta = json.load(f)
+
+        searcher.embedding_model = searcher.meta["embedding_model"]
+        searcher.embedding_mode = searcher.meta.get("embedding_mode", "sentence-transformers")
+        searcher.embedding_options = searcher.meta.get("embedding_options", {})
+
+        # Mock compute_embeddings to capture the query text
+        captured_queries = []
+
+        def mock_compute_embeddings(texts, model, mode, provider_options=None):
+            captured_queries.extend(texts)
+            return np.random.rand(len(texts), 768).astype(np.float32)
+
+        with patch(
+            "leann.embedding_compute.compute_embeddings", side_effect=mock_compute_embeddings
+        ):
+            # Call compute_query_embedding with template (fallback path)
+            result = searcher.compute_query_embedding(
+                query="vector database",
+                use_server_if_available=False,  # Force fallback path
+                query_template="task: search result | query: ",
+            )
+
+        # Verify template was applied
+        assert len(captured_queries) == 1
+        assert captured_queries[0] == "task: search result | query: vector database"
+        assert result.shape == (1, 768)
+
+    def test_query_template_applied_in_server_path(self, temp_index_with_template):
+        """Test that query template is applied when using server path"""
+        from leann.searcher_base import BaseSearcher
+
+        # Create a concrete implementation for testing
+        class TestSearcher(BaseSearcher):
+            def search(self, query_vectors, top_k, complexity, beam_width=1, **kwargs):
+                return {"labels": [], "distances": []}
+
+        searcher = object.__new__(TestSearcher)
+        searcher.index_path = Path(temp_index_with_template)
+        searcher.index_dir = searcher.index_path.parent
+
+        # Load metadata
+        meta_file = searcher.index_dir / f"{searcher.index_path.name}.meta.json"
+        with open(meta_file) as f:
+            searcher.meta = json.load(f)
+
+        searcher.embedding_model = searcher.meta["embedding_model"]
+        searcher.embedding_mode = searcher.meta.get("embedding_mode", "sentence-transformers")
+        searcher.embedding_options = searcher.meta.get("embedding_options", {})
+
+        # Mock the server methods to capture the query text
+        captured_queries = []
+
+        def mock_ensure_server_running(passages_file, port):
+            return port
+
+        def mock_compute_embedding_via_server(chunks, port):
+            captured_queries.extend(chunks)
+            return np.random.rand(len(chunks), 768).astype(np.float32)
+
+        searcher._ensure_server_running = mock_ensure_server_running
+        searcher._compute_embedding_via_server = mock_compute_embedding_via_server
+
+        # Call compute_query_embedding with template (server path)
+        result = searcher.compute_query_embedding(
+            query="vector database",
+            use_server_if_available=True,  # Use server path
+            query_template="task: search result | query: ",
+        )
+
+        # Verify template was applied BEFORE calling server
+        assert len(captured_queries) == 1
+        assert captured_queries[0] == "task: search result | query: vector database"
+        assert result.shape == (1, 768)
+
+    def test_query_template_without_template_parameter(self, temp_index_with_template):
+        """Test that query is unchanged when no template is provided"""
+        from leann.searcher_base import BaseSearcher
+
+        class TestSearcher(BaseSearcher):
+            def search(self, query_vectors, top_k, complexity, beam_width=1, **kwargs):
+                return {"labels": [], "distances": []}
+
+        searcher = object.__new__(TestSearcher)
+        searcher.index_path = Path(temp_index_with_template)
+        searcher.index_dir = searcher.index_path.parent
+
+        meta_file = searcher.index_dir / f"{searcher.index_path.name}.meta.json"
+        with open(meta_file) as f:
+            searcher.meta = json.load(f)
+
+        searcher.embedding_model = searcher.meta["embedding_model"]
+        searcher.embedding_mode = searcher.meta.get("embedding_mode", "sentence-transformers")
+        searcher.embedding_options = searcher.meta.get("embedding_options", {})
+
+        captured_queries = []
+
+        def mock_compute_embeddings(texts, model, mode, provider_options=None):
+            captured_queries.extend(texts)
+            return np.random.rand(len(texts), 768).astype(np.float32)
+
+        with patch(
+            "leann.embedding_compute.compute_embeddings", side_effect=mock_compute_embeddings
+        ):
+            searcher.compute_query_embedding(
+                query="vector database",
+                use_server_if_available=False,
+                query_template=None,  # No template
+            )
+
+        # Verify query is unchanged
+        assert len(captured_queries) == 1
+        assert captured_queries[0] == "vector database"
+
+    def test_query_template_consistency_between_paths(self, temp_index_with_template):
+        """Test that both paths apply template identically"""
+        from leann.searcher_base import BaseSearcher
+
+        class TestSearcher(BaseSearcher):
+            def search(self, query_vectors, top_k, complexity, beam_width=1, **kwargs):
+                return {"labels": [], "distances": []}
+
+        searcher = object.__new__(TestSearcher)
+        searcher.index_path = Path(temp_index_with_template)
+        searcher.index_dir = searcher.index_path.parent
+
+        meta_file = searcher.index_dir / f"{searcher.index_path.name}.meta.json"
+        with open(meta_file) as f:
+            searcher.meta = json.load(f)
+
+        searcher.embedding_model = searcher.meta["embedding_model"]
+        searcher.embedding_mode = searcher.meta.get("embedding_mode", "sentence-transformers")
+        searcher.embedding_options = searcher.meta.get("embedding_options", {})
+
+        query_template = "task: search result | query: "
+        original_query = "vector database"
+
+        # Capture queries from fallback path
+        fallback_queries = []
+
+        def mock_compute_embeddings(texts, model, mode, provider_options=None):
+            fallback_queries.extend(texts)
+            return np.random.rand(len(texts), 768).astype(np.float32)
+
+        with patch(
+            "leann.embedding_compute.compute_embeddings", side_effect=mock_compute_embeddings
+        ):
+            searcher.compute_query_embedding(
+                query=original_query,
+                use_server_if_available=False,
+                query_template=query_template,
+            )
+
+        # Capture queries from server path
+        server_queries = []
+
+        def mock_ensure_server_running(passages_file, port):
+            return port
+
+        def mock_compute_embedding_via_server(chunks, port):
+            server_queries.extend(chunks)
+            return np.random.rand(len(chunks), 768).astype(np.float32)
+
+        searcher._ensure_server_running = mock_ensure_server_running
+        searcher._compute_embedding_via_server = mock_compute_embedding_via_server
+
+        searcher.compute_query_embedding(
+            query=original_query,
+            use_server_if_available=True,
+            query_template=query_template,
+        )
+
+        # Verify both paths produced identical templated queries
+        assert len(fallback_queries) == 1
+        assert len(server_queries) == 1
+        assert fallback_queries[0] == server_queries[0]
+        assert fallback_queries[0] == f"{query_template}{original_query}"
+
+    def test_query_template_with_empty_string(self, temp_index_with_template):
+        """Test behavior with empty template string"""
+        from leann.searcher_base import BaseSearcher
+
+        class TestSearcher(BaseSearcher):
+            def search(self, query_vectors, top_k, complexity, beam_width=1, **kwargs):
+                return {"labels": [], "distances": []}
+
+        searcher = object.__new__(TestSearcher)
+        searcher.index_path = Path(temp_index_with_template)
+        searcher.index_dir = searcher.index_path.parent
+
+        meta_file = searcher.index_dir / f"{searcher.index_path.name}.meta.json"
+        with open(meta_file) as f:
+            searcher.meta = json.load(f)
+
+        searcher.embedding_model = searcher.meta["embedding_model"]
+        searcher.embedding_mode = searcher.meta.get("embedding_mode", "sentence-transformers")
+        searcher.embedding_options = searcher.meta.get("embedding_options", {})
+
+        captured_queries = []
+
+        def mock_compute_embeddings(texts, model, mode, provider_options=None):
+            captured_queries.extend(texts)
+            return np.random.rand(len(texts), 768).astype(np.float32)
+
+        with patch(
+            "leann.embedding_compute.compute_embeddings", side_effect=mock_compute_embeddings
+        ):
+            searcher.compute_query_embedding(
+                query="vector database",
+                use_server_if_available=False,
+                query_template="",  # Empty string
+            )
+
+        # Empty string is falsy, so no template should be applied
+        assert captured_queries[0] == "vector database"

tests/test_token_truncation.py

@@ -266,3 +266,378 @@ class TestTokenTruncation:
         assert result_tokens <= target_tokens, (
             f"Should be ≤{target_tokens} tokens, got {result_tokens}"
         )
+
+
+class TestLMStudioHybridDiscovery:
+    """Tests for LM Studio integration in get_model_token_limit() hybrid discovery.
+
+    These tests verify that get_model_token_limit() properly integrates with
+    the LM Studio SDK bridge for dynamic token limit discovery. The integration
+    should:
+
+    1. Detect LM Studio URLs (port 1234 or 'lmstudio'/'lm.studio' in URL)
+    2. Convert HTTP URLs to WebSocket format for SDK queries
+    3. Query LM Studio SDK and use discovered limit
+    4. Fall back to registry when SDK returns None
+    5. Execute AFTER Ollama detection but BEFORE registry fallback
+
+    All tests are written in Red Phase - they should FAIL initially because the
+    LM Studio detection and integration logic does not exist yet in get_model_token_limit().
+    """
+
+    def test_get_model_token_limit_lmstudio_success(self, monkeypatch):
+        """Verify LM Studio SDK query succeeds and returns detected limit.
+
+        When a LM Studio base_url is detected and the SDK query succeeds,
+        get_model_token_limit() should return the dynamically discovered
+        context length without falling back to the registry.
+        """
+
+        # Mock _query_lmstudio_context_limit to return successful SDK query
+        def mock_query_lmstudio(model_name, base_url):
+            # Verify WebSocket URL was passed (not HTTP)
+            assert base_url.startswith("ws://"), (
+                f"Should convert HTTP to WebSocket format, got: {base_url}"
+            )
+            return 8192  # Successful SDK query
+
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_lmstudio_context_limit",
+            mock_query_lmstudio,
+        )
+
+        # Test with HTTP URL that should be converted to WebSocket
+        limit = get_model_token_limit(
+            model_name="custom-model", base_url="http://localhost:1234/v1"
+        )
+
+        assert limit == 8192, "Should return limit from LM Studio SDK query"
+
+    def test_get_model_token_limit_lmstudio_fallback_to_registry(self, monkeypatch):
+        """Verify fallback to registry when LM Studio SDK returns None.
+
+        When LM Studio SDK query fails (returns None), get_model_token_limit()
+        should fall back to the EMBEDDING_MODEL_LIMITS registry.
+        """
+
+        # Mock _query_lmstudio_context_limit to return None (SDK failure)
+        def mock_query_lmstudio(model_name, base_url):
+            return None  # SDK query failed
+
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_lmstudio_context_limit",
+            mock_query_lmstudio,
+        )
+
+        # Test with known model that exists in registry
+        limit = get_model_token_limit(
+            model_name="nomic-embed-text", base_url="http://localhost:1234/v1"
+        )
+
+        # Should fall back to registry value
+        assert limit == 2048, "Should fall back to registry when SDK returns None"
+
+    def test_get_model_token_limit_lmstudio_port_detection(self, monkeypatch):
+        """Verify detection of LM Studio via port 1234.
+
+        get_model_token_limit() should recognize port 1234 as a LM Studio
+        server and attempt SDK query, regardless of hostname.
+        """
+        query_called = False
+
+        def mock_query_lmstudio(model_name, base_url):
+            nonlocal query_called
+            query_called = True
+            return 4096
+
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_lmstudio_context_limit",
+            mock_query_lmstudio,
+        )
+
+        # Test with port 1234 (default LM Studio port)
+        limit = get_model_token_limit(model_name="test-model", base_url="http://127.0.0.1:1234/v1")
+
+        assert query_called, "Should detect port 1234 and call LM Studio SDK query"
+        assert limit == 4096, "Should return SDK query result"
+
+    @pytest.mark.parametrize(
+        "test_url,expected_limit,keyword",
+        [
+            ("http://lmstudio.local:8080/v1", 16384, "lmstudio"),
+            ("http://api.lm.studio:5000/v1", 32768, "lm.studio"),
+        ],
+    )
+    def test_get_model_token_limit_lmstudio_url_keyword_detection(
+        self, monkeypatch, test_url, expected_limit, keyword
+    ):
+        """Verify detection of LM Studio via keywords in URL.
+
+        get_model_token_limit() should recognize 'lmstudio' or 'lm.studio'
+        in the URL as indicating a LM Studio server.
+        """
+        query_called = False
+
+        def mock_query_lmstudio(model_name, base_url):
+            nonlocal query_called
+            query_called = True
+            return expected_limit
+
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_lmstudio_context_limit",
+            mock_query_lmstudio,
+        )
+
+        limit = get_model_token_limit(model_name="test-model", base_url=test_url)
+
+        assert query_called, f"Should detect '{keyword}' keyword and call SDK query"
+        assert limit == expected_limit, f"Should return SDK query result for {keyword}"
+
+    @pytest.mark.parametrize(
+        "input_url,expected_protocol,expected_host",
+        [
+            ("http://localhost:1234/v1", "ws://", "localhost:1234"),
+            ("https://lmstudio.example.com:1234/v1", "wss://", "lmstudio.example.com:1234"),
+        ],
+    )
+    def test_get_model_token_limit_protocol_conversion(
+        self, monkeypatch, input_url, expected_protocol, expected_host
+    ):
+        """Verify HTTP/HTTPS URL is converted to WebSocket format for SDK query.
+
+        LM Studio SDK requires WebSocket URLs. get_model_token_limit() should:
+        1. Convert 'http://' to 'ws://'
+        2. Convert 'https://' to 'wss://'
+        3. Remove '/v1' or other path suffixes (SDK expects base URL)
+        4. Preserve host and port
+        """
+        conversions_tested = []
+
+        def mock_query_lmstudio(model_name, base_url):
+            conversions_tested.append(base_url)
+            return 8192
+
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_lmstudio_context_limit",
+            mock_query_lmstudio,
+        )
+
+        get_model_token_limit(model_name="test-model", base_url=input_url)
+
+        # Verify conversion happened
+        assert len(conversions_tested) == 1, "Should have called SDK query once"
+        assert conversions_tested[0].startswith(expected_protocol), (
+            f"Should convert to {expected_protocol}"
+        )
+        assert expected_host in conversions_tested[0], (
+            f"Should preserve host and port: {expected_host}"
+        )
+
+    def test_get_model_token_limit_lmstudio_executes_after_ollama(self, monkeypatch):
+        """Verify LM Studio detection happens AFTER Ollama detection.
+
+        The hybrid discovery order should be:
+        1. Ollama dynamic discovery (port 11434 or 'ollama' in URL)
+        2. LM Studio dynamic discovery (port 1234 or 'lmstudio' in URL)
+        3. Registry fallback
+
+        If both Ollama and LM Studio patterns match, Ollama should take precedence.
+        This test verifies that LM Studio is checked but doesn't interfere with Ollama.
+        """
+        ollama_called = False
+        lmstudio_called = False
+
+        def mock_query_ollama(model_name, base_url):
+            nonlocal ollama_called
+            ollama_called = True
+            return 2048  # Ollama query succeeds
+
+        def mock_query_lmstudio(model_name, base_url):
+            nonlocal lmstudio_called
+            lmstudio_called = True
+            return None  # Should not be reached if Ollama succeeds
+
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_ollama_context_limit",
+            mock_query_ollama,
+        )
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_lmstudio_context_limit",
+            mock_query_lmstudio,
+        )
+
+        # Test with Ollama URL
+        limit = get_model_token_limit(
+            model_name="test-model", base_url="http://localhost:11434/api"
+        )
+
+        assert ollama_called, "Should attempt Ollama query first"
+        assert not lmstudio_called, "Should not attempt LM Studio query when Ollama succeeds"
+        assert limit == 2048, "Should return Ollama result"
+
+    def test_get_model_token_limit_lmstudio_not_detected_for_non_lmstudio_urls(self, monkeypatch):
+        """Verify LM Studio SDK query is NOT called for non-LM Studio URLs.
+
+        Only URLs with port 1234 or 'lmstudio'/'lm.studio' keywords should
+        trigger LM Studio SDK queries. Other URLs should skip to registry fallback.
+        """
+        lmstudio_called = False
+
+        def mock_query_lmstudio(model_name, base_url):
+            nonlocal lmstudio_called
+            lmstudio_called = True
+            return 8192
+
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_lmstudio_context_limit",
+            mock_query_lmstudio,
+        )
+
+        # Test with non-LM Studio URLs
+        test_cases = [
+            "http://localhost:8080/v1",  # Different port
+            "http://openai.example.com/v1",  # Different service
+            "http://localhost:3000/v1",  # Another port
+        ]
+
+        for base_url in test_cases:
+            lmstudio_called = False  # Reset for each test
+            get_model_token_limit(model_name="nomic-embed-text", base_url=base_url)
+            assert not lmstudio_called, f"Should NOT call LM Studio SDK for URL: {base_url}"
+
+    def test_get_model_token_limit_lmstudio_case_insensitive_detection(self, monkeypatch):
+        """Verify LM Studio detection is case-insensitive for keywords.
+
+        Keywords 'lmstudio' and 'lm.studio' should be detected regardless
+        of case (LMStudio, LMSTUDIO, LmStudio, etc.).
+        """
+        query_called = False
+
+        def mock_query_lmstudio(model_name, base_url):
+            nonlocal query_called
+            query_called = True
+            return 8192
+
+        monkeypatch.setattr(
+            "leann.embedding_compute._query_lmstudio_context_limit",
+            mock_query_lmstudio,
+        )
+
+        # Test various case variations
+        test_cases = [
+            "http://LMStudio.local:8080/v1",
+            "http://LMSTUDIO.example.com/v1",
+            "http://LmStudio.local/v1",
+            "http://api.LM.STUDIO:5000/v1",
+        ]
+
+        for base_url in test_cases:
+            query_called = False  # Reset for each test
+            limit = get_model_token_limit(model_name="test-model", base_url=base_url)
+            assert query_called, f"Should detect LM Studio in URL: {base_url}"
+            assert limit == 8192, f"Should return SDK result for URL: {base_url}"
+
+
+class TestTokenLimitCaching:
+    """Tests for token limit caching to prevent repeated SDK/API calls.
+
+    Caching prevents duplicate SDK/API calls within the same Python process,
+    which is important because:
+    1. LM Studio SDK load() can load duplicate model instances
+    2. Ollama /api/show queries add latency
+    3. Registry lookups are pure overhead
+
+    Cache is process-scoped and resets between leann build invocations.
+    """
+
+    def setup_method(self):
+        """Clear cache before each test."""
+        from leann.embedding_compute import _token_limit_cache
+
+        _token_limit_cache.clear()
+
+    def test_registry_lookup_is_cached(self):
+        """Verify that registry lookups are cached."""
+        from leann.embedding_compute import _token_limit_cache
+
+        # First call
+        limit1 = get_model_token_limit("text-embedding-3-small")
+        assert limit1 == 8192
+
+        # Verify it's in cache
+        cache_key = ("text-embedding-3-small", "")
+        assert cache_key in _token_limit_cache
+        assert _token_limit_cache[cache_key] == 8192
+
+        # Second call should use cache
+        limit2 = get_model_token_limit("text-embedding-3-small")
+        assert limit2 == 8192
+
+    def test_default_fallback_is_cached(self):
+        """Verify that default fallbacks are cached."""
+        from leann.embedding_compute import _token_limit_cache
+
+        # First call with unknown model
+        limit1 = get_model_token_limit("unknown-model-xyz", default=512)
+        assert limit1 == 512
+
+        # Verify it's in cache
+        cache_key = ("unknown-model-xyz", "")
+        assert cache_key in _token_limit_cache
+        assert _token_limit_cache[cache_key] == 512
+
+        # Second call should use cache
+        limit2 = get_model_token_limit("unknown-model-xyz", default=512)
+        assert limit2 == 512
+
+    def test_different_urls_create_separate_cache_entries(self):
+        """Verify that different base_urls create separate cache entries."""
+        from leann.embedding_compute import _token_limit_cache
+
+        # Same model, different URLs
+        limit1 = get_model_token_limit("nomic-embed-text", base_url="http://localhost:11434")
+        limit2 = get_model_token_limit("nomic-embed-text", base_url="http://localhost:1234/v1")
+
+        # Both should find the model in registry (2048)
+        assert limit1 == 2048
+        assert limit2 == 2048
+
+        # But they should be separate cache entries
+        cache_key1 = ("nomic-embed-text", "http://localhost:11434")
+        cache_key2 = ("nomic-embed-text", "http://localhost:1234/v1")
+
+        assert cache_key1 in _token_limit_cache
+        assert cache_key2 in _token_limit_cache
+        assert len(_token_limit_cache) == 2
+
+    def test_cache_prevents_repeated_lookups(self):
+        """Verify that cache prevents repeated registry/API lookups."""
+        from leann.embedding_compute import _token_limit_cache
+
+        model_name = "text-embedding-ada-002"
+
+        # First call - should add to cache
+        assert len(_token_limit_cache) == 0
+        limit1 = get_model_token_limit(model_name)
+
+        cache_size_after_first = len(_token_limit_cache)
+        assert cache_size_after_first == 1
+
+        # Multiple subsequent calls - cache size should not change
+        for _ in range(5):
+            limit = get_model_token_limit(model_name)
+            assert limit == limit1
+            assert len(_token_limit_cache) == cache_size_after_first
+
+    def test_versioned_model_names_cached_correctly(self):
+        """Verify that versioned model names (e.g., model:tag) are cached."""
+        from leann.embedding_compute import _token_limit_cache
+
+        # Model with version tag
+        limit = get_model_token_limit("nomic-embed-text:latest", base_url="http://localhost:11434")
+        assert limit == 2048
+
+        # Should be cached with full name including version
+        cache_key = ("nomic-embed-text:latest", "http://localhost:11434")
+        assert cache_key in _token_limit_cache
+        assert _token_limit_cache[cache_key] == 2048