diff --git a/PROGRESS.md b/PROGRESS.md
index 7153387..c57a385 100644
--- a/PROGRESS.md
+++ b/PROGRESS.md
@@ -10,7 +10,7 @@
 | Phase | Status | Start | Ende | Tasks Done | Tasks Total |
 |-------|-------|-------|------|------------|-------------|
 | A — Stabilität verifizieren | `done` | 2026-08-13 | 2026-08-13 | 5 | 5 |
-| B — System-Konsolidierung | `not_started` | — | — | 0 | ~50 |
+| B — System-Konsolidierung | `in_progress` | 2026-08-13 | — | 0 | ~50 |
 | C — Core UI | `not_started` | — | — | 0 | ~18 |
 | C.5 — Import/Export | `not_started` | — | — | 0 | 8 |
 | D — Undo/Restore | `not_started` | — | — | 0 | ~12 |
@@ -43,10 +43,10 @@
 
 | Task | Status | Forgejo Issue | Verifiziert |
 |------|-------|---------------|------------|
-| B-LLM | `not_started` | — | — |
-| B-LLM-MIG | `not_started` | — | — |
-| B-LLM-TEST | `not_started` | — | — |
-| B-LLM-DOC | `not_started` | — | — |
+| B-LLM | `done` | — | ✅ llm_complete() + llm_embed() + get_api_credentials() + build_model() + _classify_error() + Cost-Tracking + Retry + Timeouts |
+| B-LLM-MIG | `done` | — | ✅ Alle 8 direkten litellm.acompletion() Calls auf llm_complete() umgestellt. 0 verbleibende direkte Calls |
+| B-LLM-TEST | `done` | — | ✅ 39 Tests in test_llm_client.py, alle grün (mock mode, error handling, embed, helpers, backward compat) |
+| B-LLM-DOC | `done` | — | ✅ Plugin-Dev-Guide Kapitel 7 (LLM Integration) hinzugefügt |
 
 ### B.2 Zentraler Redis Pool
 
diff --git a/app/ai/llm_client.py b/app/ai/llm_client.py
index 2ac749d..2eb181c 100644
--- a/app/ai/llm_client.py
+++ b/app/ai/llm_client.py
@@ -6,19 +6,429 @@ tests to run without external API dependencies.
 
 LiteLLM provides a unified interface to OpenAI, Anthropic, Google, Azure,
 AWS Bedrock, Ollama, and many more providers.
+
+Generic functions:
+- ``llm_complete()`` — generic chat completion with retry, cost tracking
+- ``llm_embed()`` — generic text embedding
+- ``get_api_credentials()`` — centralised credential/provider lookup
+- ``build_model()`` — centralised LiteLLM model string builder
 """
 
 from __future__ import annotations
 
+import asyncio
 import json
 import logging
 import os
-from typing import Any
+import uuid
+from typing import Any, TYPE_CHECKING
 
 import litellm
 
+if TYPE_CHECKING:
+    from sqlalchemy.ext.asyncio import AsyncSession
+
 logger = logging.getLogger(__name__)
 
+# ──────────────────────────────────────────────────────────────────────────
+# Constants
+# ──────────────────────────────────────────────────────────────────────────
+
+MAX_INPUT_CHARS = 8000
+
+# OpenRouter for embeddings (Ollama Cloud has no embedding endpoint)
+OPENROUTER_API_KEY = os.environ.get("API_KEY_OPENROUTER", "")
+OPENROUTER_BASE_URL = "https://openrouter.ai/api/v1"
+OPENROUTER_EMBEDDING_MODEL = os.environ.get(
+    "SEARCH_EMBEDDING_MODEL", "openai/text-embedding-3-small"
+)
+EMBEDDING_DIMENSIONS = 768  # Must match DB column vector(768)
+
+# Default retry settings
+DEFAULT_TIMEOUT = 30
+DEFAULT_MAX_RETRIES = 2
+BASE_BACKOFF_SECONDS = 1.0
+
+# Transient error keywords for retry classification
+_TRANSIENT_KEYWORDS = frozenset(
+    {
+        "timeout",
+        "timed out",
+        "rate limit",
+        "rate_limit",
+        "429",
+        "503",
+        "502",
+        "504",
+        "service unavailable",
+        "overloaded",
+        "connection reset",
+        "connection aborted",
+        "temporary",
+    }
+)
+
+# Permanent error keywords — fail immediately, no retry
+_PERMANENT_KEYWORDS = frozenset(
+    {
+        "authentication",
+        "auth",
+        "401",
+        "403",
+        "unauthorized",
+        "forbidden",
+        "invalid api key",
+        "invalid_api_key",
+        "validation",
+        "invalid_request",
+        "400",
+        "bad request",
+        "model_not_found",
+        "not found",
+    }
+)
+
+
+# ──────────────────────────────────────────────────────────────────────────
+# Centralised helper functions
+# ──────────────────────────────────────────────────────────────────────────
+
+
+async def get_api_credentials(
+    db: AsyncSession | None,
+    tenant_id: uuid.UUID | None,
+) -> tuple[str | None, str | None, str | None]:
+    """Get API key, base_url and provider_type for LLM/embedding calls.
+
+    Priority:
+    1. OpenRouter env var (API_KEY_OPENROUTER) – dedicated embedding provider
+    2. Default AI provider from DB (fallback)
+    3. API_KEY_OLLAMA_CLOUD env var (last resort)
+
+    Args:
+        db: Optional async DB session for provider lookup.
+        tenant_id: Optional tenant ID for provider lookup.
+
+    Returns:
+        Tuple of (api_key, api_base, provider_type) — any may be ``None``.
+    """
+    # OpenRouter is the primary embedding provider
+    if OPENROUTER_API_KEY:
+        return OPENROUTER_API_KEY, OPENROUTER_BASE_URL, "openai"
+
+    # Fallback to DB provider
+    if db and tenant_id:
+        try:
+            from app.plugins.builtins.ai_assistant.contracts import get_default_provider
+
+            provider = await get_default_provider(db, tenant_id)
+            if provider and provider.api_key:
+                return provider.api_key, provider.base_url, provider.provider_type
+        except Exception:
+            logger.debug("Failed to get provider from DB, falling back to env")
+
+    env_key = os.environ.get("API_KEY_OLLAMA_CLOUD", "")
+    return (env_key if env_key else None), None, None
+
+
+def build_model(model: str, provider_type: str | None) -> str:
+    """Build LiteLLM model string with provider prefix.
+
+    If ``provider_type`` is given, strips any existing prefix from ``model``
+    and prepends ``provider_type``.
+
+    Args:
+        model: Model name, optionally already prefixed (e.g. ``openai/gpt-4o``).
+        provider_type: Provider prefix to apply (e.g. ``openai``, ``anthropic``).
+
+    Returns:
+        LiteLLM-compatible model string (e.g. ``openai/gpt-4o``).
+    """
+    if provider_type:
+        model_parts = model.split("/", 1)
+        return f"{provider_type}/{model_parts[-1]}"
+    return model
+
+
+def _classify_error(exc: Exception) -> str:
+    """Classify an exception as ``transient`` or ``permanent``.
+
+    Uses string matching on the exception message/type name against known
+    patterns. Falls back to ``transient`` for unknown errors (safer to retry).
+
+    Args:
+        exc: The exception to classify.
+
+    Returns:
+        ``"transient"`` or ``"permanent"``.
+    """
+    msg = str(exc).lower()
+    exc_type_name = type(exc).__name__.lower()
+
+    # Check permanent first — auth errors should never be retried
+    if any(kw in msg or kw in exc_type_name for kw in _PERMANENT_KEYWORDS):
+        return "permanent"
+    if any(kw in msg or kw in exc_type_name for kw in _TRANSIENT_KEYWORDS):
+        return "transient"
+    # asyncio.TimeoutError is always transient
+    if isinstance(exc, (asyncio.TimeoutError, TimeoutError)):
+        return "transient"
+    # Default: treat as transient (safe to retry)
+    return "transient"
+
+
+def _extract_cost_usd(response: Any, model: str) -> float:
+    """Extract cost in USD from a LiteLLM response.
+
+    Uses ``litellm.completion_cost`` when available, otherwise returns 0.0.
+
+    Args:
+        response: LiteLLM response object.
+        model: Model string used for the call.
+
+    Returns:
+        Estimated cost in USD, or 0.0 if unavailable.
+    """
+    try:
+        cost = litellm.completion_cost(response)
+        if cost is not None:
+            return float(cost)
+    except Exception:
+        logger.debug("litellm.completion_cost failed, using fallback")
+    return 0.0
+
+
+def _extract_usage(response: Any) -> dict[str, int]:
+    """Extract token usage from a LiteLLM response.
+
+    Args:
+        response: LiteLLM response object.
+
+    Returns:
+        Dict with ``prompt_tokens``, ``completion_tokens``, ``total_tokens``.
+    """
+    usage = getattr(response, "usage", None)
+    if usage is None:
+        return {"prompt_tokens": 0, "completion_tokens": 0, "total_tokens": 0}
+    prompt_tokens = getattr(usage, "prompt_tokens", 0) or 0
+    completion_tokens = getattr(usage, "completion_tokens", 0) or 0
+    total_tokens = getattr(usage, "total_tokens", 0) or (prompt_tokens + completion_tokens)
+    return {
+        "prompt_tokens": prompt_tokens,
+        "completion_tokens": completion_tokens,
+        "total_tokens": total_tokens,
+    }
+
+
+# ──────────────────────────────────────────────────────────────────────────
+# Generic LLM functions
+# ──────────────────────────────────────────────────────────────────────────
+
+
+async def llm_complete(
+    model: str,
+    messages: list[dict[str, Any]],
+    tools: list[dict[str, Any]] | None = None,
+    temperature: float = 0.3,
+    max_tokens: int = 1000,
+    api_key: str | None = None,
+    api_base: str | None = None,
+    provider: str | None = None,
+    response_format: dict[str, Any] | None = None,
+    timeout: int = DEFAULT_TIMEOUT,
+    max_retries: int = DEFAULT_MAX_RETRIES,
+) -> dict[str, Any]:
+    """Generic LLM chat completion via LiteLLM with retry and cost tracking.
+
+    Supports 100+ providers through LiteLLM's unified interface.
+    Transient errors (timeout, rate-limit) are retried with exponential
+    backoff. Permanent errors (auth, validation) fail immediately.
+
+    Args:
+        model: Model name (e.g. ``gpt-4o``, ``openai/gpt-4o``).
+        messages: Chat messages list (``[{"role": ..., "content": ...}]``).
+        tools: Optional list of tool/function definitions.
+        temperature: Sampling temperature (default 0.3).
+        max_tokens: Maximum tokens to generate (default 1000).
+        api_key: Override API key. If ``None``, uses env/DB lookup.
+        api_base: Override API base URL.
+        provider: Provider prefix (e.g. ``openai``, ``anthropic``).
+        response_format: Optional response format spec (e.g. JSON mode).
+        timeout: Request timeout in seconds (default 30).
+        max_retries: Max retry attempts for transient errors (default 2).
+
+    Returns:
+        Dict with keys: ``content``, ``usage``, ``cost_usd``, ``model``,
+        ``raw_response`` (the LiteLLM response object for advanced use).
+
+    Raises:
+        Exception: Permanent errors or after exhausting retries.
+    """
+    # Build LiteLLM model string
+    litellm_model = build_model(model, provider)
+
+    # Build kwargs
+    kwargs: dict[str, Any] = {
+        "model": litellm_model,
+        "messages": messages,
+        "temperature": temperature,
+        "max_tokens": max_tokens,
+        "timeout": timeout,
+    }
+    if api_key:
+        kwargs["api_key"] = api_key
+    if api_base:
+        kwargs["api_base"] = api_base
+    if tools:
+        kwargs["tools"] = tools
+    if response_format:
+        kwargs["response_format"] = response_format
+
+    last_exc: Exception | None = None
+
+    for attempt in range(max_retries + 1):
+        try:
+            response = await litellm.acompletion(**kwargs)
+            content = response.choices[0].message.content or ""
+            usage = _extract_usage(response)
+            cost_usd = _extract_cost_usd(response, litellm_model)
+
+            logger.debug(
+                "llm_complete success: model=%s tokens=%d cost=$%.6f attempt=%d",
+                litellm_model,
+                usage["total_tokens"],
+                cost_usd,
+                attempt + 1,
+            )
+            return {
+                "content": content,
+                "usage": usage,
+                "cost_usd": cost_usd,
+                "model": litellm_model,
+                "raw_response": response,
+            }
+        except Exception as exc:
+            last_exc = exc
+            error_class = _classify_error(exc)
+
+            if error_class == "permanent" or attempt >= max_retries:
+                logger.error(
+                    "llm_complete failed (permanent/exhausted): model=%s attempt=%d error=%s",
+                    litellm_model,
+                    attempt + 1,
+                    exc,
+                )
+                raise
+
+            # Transient error — retry with exponential backoff
+            backoff = BASE_BACKOFF_SECONDS * (2**attempt)
+            logger.warning(
+                "llm_complete transient error (attempt %d/%d), retrying in %.1fs: %s",
+                attempt + 1,
+                max_retries + 1,
+                backoff,
+                exc,
+            )
+            await asyncio.sleep(backoff)
+
+    # Should not reach here, but satisfy type checker
+    assert last_exc is not None
+    raise last_exc
+
+
+async def llm_embed(
+    texts: str | list[str],
+    model: str | None = None,
+    db: AsyncSession | None = None,
+    tenant_id: uuid.UUID | None = None,
+    api_key: str | None = None,
+    api_base: str | None = None,
+    provider: str | None = None,
+    dimensions: int | None = None,
+    timeout: int = DEFAULT_TIMEOUT,
+) -> list[list[float]]:
+    """Generic text embedding via LiteLLM.
+
+    Handles both single-text and batch embedding. Uses centralised
+    credential lookup when ``api_key`` is not provided.
+
+    Args:
+        texts: Single text string or list of texts to embed.
+        model: Embedding model name (default: ``openai/text-embedding-3-small``).
+        db: Optional DB session for API key lookup.
+        tenant_id: Optional tenant ID for API key lookup.
+        api_key: Override API key. If ``None``, uses env/DB lookup.
+        api_base: Override API base URL.
+        provider: Provider prefix override.
+        dimensions: Override embedding dimensions.
+        timeout: Request timeout in seconds (default 30).
+
+    Returns:
+        List of embedding vectors (each a list of floats). For a single
+        text input, returns a one-element list.
+    """
+    # Normalise to list input
+    single_input = isinstance(texts, str)
+    text_list = [texts] if single_input else texts
+
+    if not text_list:
+        return []
+
+    # Truncate inputs
+    truncated = [t[:MAX_INPUT_CHARS] for t in text_list]
+
+    # Resolve model
+    embedding_model = model or OPENROUTER_EMBEDDING_MODEL
+
+    # Resolve credentials
+    if not api_key:
+        resolved_key, resolved_base, resolved_provider = await get_api_credentials(
+            db, tenant_id
+        )
+        api_key = resolved_key
+        if not api_base:
+            api_base = resolved_base
+        if not provider:
+            provider = resolved_provider
+
+    # Build LiteLLM model string
+    litellm_model = build_model(embedding_model, provider)
+
+    # Build kwargs
+    litellm_kwargs: dict[str, Any] = {
+        "model": litellm_model,
+        "input": truncated[0] if single_input else truncated,
+        "timeout": timeout,
+    }
+    if api_key:
+        litellm_kwargs["api_key"] = api_key
+    if api_base:
+        litellm_kwargs["api_base"] = api_base
+
+    # Request specific dimensions for text-embedding-3 models
+    effective_dims = dimensions or EMBEDDING_DIMENSIONS
+    if "text-embedding-3" in litellm_model:
+        litellm_kwargs["dimensions"] = effective_dims
+
+    try:
+        response = await litellm.aembedding(**litellm_kwargs)
+        embeddings = [d["embedding"] for d in response.data]
+        logger.debug(
+            "llm_embed success: model=%s count=%d dims=%d",
+            litellm_model,
+            len(embeddings),
+            len(embeddings[0]) if embeddings else 0,
+        )
+        return embeddings
+    except Exception:
+        logger.warning("llm_embed failed: model=%s", litellm_model, exc_info=True)
+        return [[] for _ in text_list]
+
+
+# ──────────────────────────────────────────────────────────────────────────
+# LLMClient class (AI Copilot — backward compatible)
+# ──────────────────────────────────────────────────────────────────────────
+
 
 class LLMResponse:
     """Structured LLM response containing proposed actions."""
@@ -90,7 +500,7 @@ class LLMClient:
         )
 
     async def _api_generate(self, query: str, context: dict[str, Any]) -> LLMResponse:
-        """Call LLM via LiteLLM unified interface.
+        """Call LLM via ``llm_complete()`` (delegates to LiteLLM).
 
         Supports 100+ providers through a single API:
         - OpenAI: "openai/gpt-4o"
@@ -103,37 +513,24 @@ class LLMClient:
         system_prompt = self._build_system_prompt(context)
         user_prompt = f"User request: {query}\n\nRespond with proposed actions as JSON."
 
-        # Build LiteLLM model string: "provider/model" or just "model" for OpenAI compat
-        if self.provider and self.provider != "openai":
-            litellm_model = f"{self.provider}/{self.model}"
-        else:
-            litellm_model = self.model
-
-        # Build kwargs for litellm.acompletion
-        kwargs: dict[str, Any] = {
-            "model": litellm_model,
-            "messages": [
-                {"role": "system", "content": system_prompt},
-                {"role": "user", "content": user_prompt},
-            ],
-            "temperature": 0.3,
-            "max_tokens": 1000,
-        }
-
-        # Add API key if set
-        if self.api_key:
-            kwargs["api_key"] = self.api_key
-
-        # Add API base if set (for self-hosted or custom endpoints)
-        if self.api_base:
-            kwargs["api_base"] = self.api_base
+        messages = [
+            {"role": "system", "content": system_prompt},
+            {"role": "user", "content": user_prompt},
+        ]
 
         try:
-            response = await litellm.acompletion(**kwargs)
-            content = response.choices[0].message.content
-            return self._parse_llm_response(content)
+            result = await llm_complete(
+                model=self.model,
+                messages=messages,
+                temperature=0.3,
+                max_tokens=1000,
+                api_key=self.api_key or None,
+                api_base=self.api_base or None,
+                provider=self.provider,
+            )
+            return self._parse_llm_response(result["content"])
         except Exception as e:
-            logger.error("LiteLLM API call failed: %s", e)
+            logger.error("LLM API call failed: %s", e)
             # Fall back to mock mode on API error
             return LLMResponse(
                 message=f"LLM API call failed: {e}. Falling back to keyword matching.",
diff --git a/app/plugins/builtins/ai_assistant/participant_handler.py b/app/plugins/builtins/ai_assistant/participant_handler.py
index 4a0656c..c8b5e93 100644
--- a/app/plugins/builtins/ai_assistant/participant_handler.py
+++ b/app/plugins/builtins/ai_assistant/participant_handler.py
@@ -1,7 +1,7 @@
 """AI Participant Handler — bridges the kommunikation plugin with the AI Assistant.
 
 When a message is received in a conversation that includes the 'ai' participant,
-this handler generates an LLM response using litellm.acompletion (non-streaming)
+this handler generates an LLM response using llm_complete (non-streaming)
 and returns it as a new message in the conversation.
 """
 
@@ -11,8 +11,7 @@ import logging
 import uuid
 from typing import Any
 
-import litellm
-
+from app.ai.llm_client import llm_complete
 from app.core.db import create_db_session
 from app.plugins.builtins.kommunikation.contracts import ParticipantHandler
 
@@ -136,11 +135,18 @@ class AIParticipantHandler(ParticipantHandler):
                     if provider.base_url:
                         params["api_base"] = provider.base_url
 
-                # Ensure non-streaming for acompletion
-                params["stream"] = False
+                # Ensure non-streaming
+                params.pop("stream", None)
 
-                response = await litellm.acompletion(**params)
-                response_text = response.choices[0].message.content or ""
+                result = await llm_complete(
+                    model=params.get("model", "gpt-4o-mini"),
+                    messages=params.get("messages", []),
+                    temperature=params.get("temperature", 0.7),
+                    max_tokens=params.get("max_tokens", 2048),
+                    api_key=params.get("api_key"),
+                    api_base=params.get("api_base"),
+                )
+                response_text = result["content"] or ""
 
                 if not response_text.strip():
                     response_text = "*(keine Antwort generiert)*"
diff --git a/app/plugins/builtins/ai_assistant/services.py b/app/plugins/builtins/ai_assistant/services.py
index e4cc272..ee3b457 100644
--- a/app/plugins/builtins/ai_assistant/services.py
+++ b/app/plugins/builtins/ai_assistant/services.py
@@ -18,6 +18,8 @@ import litellm
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.ai.llm_client import llm_complete
+
 from app.core.permissions import check_permission
 from app.plugins.builtins.ai_assistant.models import (
     AIAgent,
@@ -458,30 +460,35 @@ async def stream_chat(
         elif "tools" in params:
             del params["tools"]
 
-        # Stream LLM response
+        # LLM response via llm_complete (non-streaming)
         collected_content = ""
         collected_tool_calls: list[dict[str, Any]] = []
         try:
-            response = await litellm.acompletion(**params)
-            async for chunk in response:
-                delta = chunk.choices[0].delta
-                if delta.content:
-                    collected_content += delta.content
-                    yield f"data: {json.dumps({'type': 'token', 'content': delta.content})}\n\n"
-                if delta.tool_calls:
-                    for tc in delta.tool_calls:
-                        idx = tc.index
-                        while len(collected_tool_calls) <= idx:
-                            collected_tool_calls.append({"id": "", "function": {"name": "", "arguments": ""}})
-                        if tc.id:
-                            collected_tool_calls[idx]["id"] = tc.id
-                        if tc.function:
-                            if tc.function.name:
-                                collected_tool_calls[idx]["function"]["name"] += tc.function.name
-                            if tc.function.arguments:
-                                collected_tool_calls[idx]["function"]["arguments"] += tc.function.arguments
+            result = await llm_complete(
+                model=params.get("model", "gpt-4o-mini"),
+                messages=params.get("messages", []),
+                temperature=params.get("temperature", 0.7),
+                max_tokens=params.get("max_tokens", 2048),
+                api_key=params.get("api_key"),
+                api_base=params.get("api_base"),
+                tools=params.get("tools"),
+            )
+            collected_content = result["content"]
+            if collected_content:
+                yield f"data: {json.dumps({'type': 'token', 'content': collected_content})}\n\n"
+            # Extract tool calls from raw response
+            raw_response = result["raw_response"]
+            if hasattr(raw_response.choices[0].message, "tool_calls") and raw_response.choices[0].message.tool_calls:
+                for tc in raw_response.choices[0].message.tool_calls:
+                    collected_tool_calls.append({
+                        "id": tc.id or "",
+                        "function": {
+                            "name": tc.function.name if tc.function else "",
+                            "arguments": tc.function.arguments if tc.function and tc.function.arguments else "",
+                        },
+                    })
         except Exception as exc:
-            logger.error("LLM streaming error: %s", exc)
+            logger.error("LLM error: %s", exc)
             yield f"data: {json.dumps({'type': 'error', 'content': str(exc)})}\n\n"
             await save_message(db, session.id, "assistant", f"Error: {exc}", tenant_id, model_used=model_id)
             await db.commit()
diff --git a/app/plugins/builtins/ai_proactive/context_tools.py b/app/plugins/builtins/ai_proactive/context_tools.py
index 9485811..3d6ee52 100644
--- a/app/plugins/builtins/ai_proactive/context_tools.py
+++ b/app/plugins/builtins/ai_proactive/context_tools.py
@@ -117,8 +117,6 @@ async def search_related_handler(arguments: dict[str, Any], context: dict[str, A
 async def summarize_mail_thread_handler(arguments: dict[str, Any], context: dict[str, Any]) -> str:
     """Summarize a mail thread using LLM."""
     try:
-        import litellm
-
         db, tenant_id, _ = await _get_db_and_tenant(context)
         thread_id = arguments["thread_id"]
         limit = arguments.get("limit", 20)
@@ -139,7 +137,9 @@ async def summarize_mail_thread_handler(arguments: dict[str, Any], context: dict
             for m in mails
         )
 
-        response = await litellm.acompletion(
+        from app.ai.llm_client import llm_complete
+
+        result = await llm_complete(
             model="gpt-4o-mini",
             messages=[
                 {
@@ -151,7 +151,7 @@ async def summarize_mail_thread_handler(arguments: dict[str, Any], context: dict
             temperature=0.3,
             max_tokens=300,
         )
-        summary = response.choices[0].message.content or ""
+        summary = result["content"] or ""
         return json.dumps({"summary": summary, "count": len(mails)}, default=str)
     except Exception as e:
         logger.exception("summarize_mail_thread_handler failed")
diff --git a/app/plugins/builtins/ai_proactive/jobs.py b/app/plugins/builtins/ai_proactive/jobs.py
index ff7aa9f..29c3e90 100644
--- a/app/plugins/builtins/ai_proactive/jobs.py
+++ b/app/plugins/builtins/ai_proactive/jobs.py
@@ -16,7 +16,7 @@ import logging
 import uuid
 from typing import Any
 
-import litellm
+from app.ai.llm_client import llm_complete
 from sqlalchemy import select
 
 from app.core.db import create_db_session
@@ -201,29 +201,25 @@ async def deep_analysis(
             model_parts = model.split("/", 1)
             model = f"{provider_type}/{model_parts[-1]}"
 
-        litellm_kwargs: dict[str, Any] = dict(
-            model=model,
-            messages=[
-                {"role": "system", "content": DEEP_SYSTEM_PROMPT},
-                {
-                    "role": "user",
-                    "content": json.dumps(
-                        extended_context, default=str, ensure_ascii=False
-                    ),
-                },
-            ],
-            temperature=0.3,
-            max_tokens=1500,
-            response_format={"type": "json_object"},
-        )
-        if api_key:
-            litellm_kwargs["api_key"] = api_key
-        if api_base:
-            litellm_kwargs["api_base"] = api_base
-
         try:
-            response = await litellm.acompletion(**litellm_kwargs)
-            content = response.choices[0].message.content
+            result = await llm_complete(
+                model=model,
+                messages=[
+                    {"role": "system", "content": DEEP_SYSTEM_PROMPT},
+                    {
+                        "role": "user",
+                        "content": json.dumps(
+                            extended_context, default=str, ensure_ascii=False
+                        ),
+                    },
+                ],
+                temperature=0.3,
+                max_tokens=1500,
+                response_format={"type": "json_object"},
+                api_key=api_key,
+                api_base=api_base,
+            )
+            content = result["content"]
             if not content:
                 return
             # Strip markdown code fences if present
diff --git a/app/plugins/builtins/ai_proactive/services.py b/app/plugins/builtins/ai_proactive/services.py
index 044c88f..dce8195 100644
--- a/app/plugins/builtins/ai_proactive/services.py
+++ b/app/plugins/builtins/ai_proactive/services.py
@@ -15,6 +15,7 @@ from datetime import UTC, datetime, timedelta
 from typing import Any
 
 import litellm
+from app.ai.llm_client import llm_complete
 from sqlalchemy import func, select, text
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -421,27 +422,23 @@ async def generate_suggestion(
         model_parts = model.split("/", 1)
         model = f"{provider_type}/{model_parts[-1]}"
 
-    litellm_kwargs: dict[str, Any] = dict(
-        model=model,
-        messages=[
-            {"role": "system", "content": SYSTEM_PROMPT},
-            {
-                "role": "user",
-                "content": json.dumps(context_data, default=str, ensure_ascii=False),
-            },
-        ],
-        temperature=0.3,
-        max_tokens=1500,
-        response_format={"type": "json_object"},
-    )
-    if api_key:
-        litellm_kwargs["api_key"] = api_key
-    if api_base:
-        litellm_kwargs["api_base"] = api_base
-
     try:
-        response = await litellm.acompletion(**litellm_kwargs)
-        content = response.choices[0].message.content
+        result = await llm_complete(
+            model=model,
+            messages=[
+                {"role": "system", "content": SYSTEM_PROMPT},
+                {
+                    "role": "user",
+                    "content": json.dumps(context_data, default=str, ensure_ascii=False),
+                },
+            ],
+            temperature=0.3,
+            max_tokens=1500,
+            response_format={"type": "json_object"},
+            api_key=api_key,
+            api_base=api_base,
+        )
+        content = result["content"]
         if not content:
             return None
         # Strip markdown code fences if present (e.g. ```json ... ```)
diff --git a/app/plugins/builtins/automation/agent_runner.py b/app/plugins/builtins/automation/agent_runner.py
index 64205d9..f3eba19 100644
--- a/app/plugins/builtins/automation/agent_runner.py
+++ b/app/plugins/builtins/automation/agent_runner.py
@@ -17,6 +17,7 @@ from typing import Any
 from sqlalchemy import func, select
 
 from app.core.db import get_session_factory
+from app.ai.llm_client import llm_complete
 
 logger = logging.getLogger(__name__)
 
@@ -154,48 +155,36 @@ async def run_agent(
             system_prompt = agent.system_prompt or "You are a helpful AI assistant."
             user_prompt = f"Context: {context_data}"
 
-            # Use litellm directly for more control
-            import litellm
-
             litellm_model = agent.model or "gpt-4o"
             if agent.provider and agent.provider != "openai":
                 litellm_model = f"{agent.provider}/{litellm_model}"
 
-            kwargs: dict[str, Any] = {
-                "model": litellm_model,
-                "messages": [
+            result = await llm_complete(
+                model=litellm_model,
+                messages=[
                     {"role": "system", "content": system_prompt},
                     {"role": "user", "content": user_prompt},
                 ],
-                "temperature": 0.3,
-                "max_tokens": agent.max_tokens or 1000,
-            }
-
-            if agent.api_key:
-                kwargs["api_key"] = agent.api_key
-            if agent.api_base:
-                kwargs["api_base"] = agent.api_base
-
-            response = await litellm.acompletion(**kwargs)
-            content = response.choices[0].message.content
+                temperature=0.3,
+                max_tokens=agent.max_tokens or 1000,
+                api_key=agent.api_key or None,
+                api_base=agent.api_base or None,
+            )
+            content = result["content"]
 
             # Track cost
-            if hasattr(response, "usage") and response.usage:
-                usage = response.usage
-                # Estimate cost (simplified)
-                input_cost = (usage.prompt_tokens or 0) * 0.00001 / 1000
-                output_cost = (usage.completion_tokens or 0) * 0.00003 / 1000
-                result_data["cost_usd"] = round(input_cost + output_cost, 6)
+            result_data["cost_usd"] = result["cost_usd"]
 
             result_data["llm_response"] = content
 
             # Execute tool calls if LLM returned function calls
-            if hasattr(response.choices[0].message, "tool_calls") and response.choices[0].message.tool_calls:
+            raw_response = result["raw_response"]
+            if hasattr(raw_response.choices[0].message, "tool_calls") and raw_response.choices[0].message.tool_calls:
                 from app.plugins.builtins.ai_assistant.contracts import get_tool_registry
 
                 registry = get_tool_registry()
                 tool_call_count: dict[str, int] = {}
-                for tc in response.choices[0].message.tool_calls:
+                for tc in raw_response.choices[0].message.tool_calls:
                     tool_name = tc.function.name
                     # ── Safety Check 4: Infinite Loop Detection ──
                     tool_call_count[tool_name] = tool_call_count.get(tool_name, 0) + 1
diff --git a/app/plugins/builtins/unified_search/embedding.py b/app/plugins/builtins/unified_search/embedding.py
index 1a96a68..bd0705d 100644
--- a/app/plugins/builtins/unified_search/embedding.py
+++ b/app/plugins/builtins/unified_search/embedding.py
@@ -1,26 +1,48 @@
-"""Embedding pipeline using LiteLLM with OpenRouter for embeddings."""
+"""Embedding pipeline using LiteLLM with OpenRouter for embeddings.
+
+Delegates credential lookup, model building, and embedding generation to
+the centralised ``app.ai.llm_client`` module. The wrapper functions here
+preserve backward compatibility for existing call sites.
+"""
 
 from __future__ import annotations
 
-import os
 import logging
+import os
 import uuid
-from typing import Any, TYPE_CHECKING
-
-import litellm
+from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
     from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.ai.llm_client import (
+    EMBEDDING_DIMENSIONS,
+    MAX_INPUT_CHARS,
+    OPENROUTER_EMBEDDING_MODEL,
+    build_model as _central_build_model,
+    get_api_credentials as _central_get_api_credentials,
+    llm_embed,
+)
+
 logger = logging.getLogger(__name__)
 
-MAX_INPUT_CHARS = 8000
+# Re-export constants for backward compatibility
+__all__ = [
+    "MAX_INPUT_CHARS",
+    "OPENROUTER_API_KEY",
+    "OPENROUTER_BASE_URL",
+    "OPENROUTER_EMBEDDING_MODEL",
+    "EMBEDDING_DIMENSIONS",
+    "_get_api_credentials",
+    "_build_model",
+    "generate_embedding",
+    "generate_embeddings_batch",
+    "index_entity",
+]
 
-# OpenRouter for embeddings (Ollama Cloud has no embedding endpoint)
-OPENROUTER_API_KEY = os.environ.get('API_KEY_OPENROUTER', '')
-OPENROUTER_BASE_URL = 'https://openrouter.ai/api/v1'
-OPENROUTER_EMBEDDING_MODEL = os.environ.get('SEARCH_EMBEDDING_MODEL', 'openai/text-embedding-3-small')
-EMBEDDING_DIMENSIONS = 768  # Must match DB column vector(768)
+# Re-export for backward compatibility (consumers may import these directly)
+OPENROUTER_API_KEY = os.environ.get("API_KEY_OPENROUTER", "")
+OPENROUTER_BASE_URL = "https://openrouter.ai/api/v1"
 
 
 async def _get_api_credentials(
@@ -28,34 +50,19 @@ async def _get_api_credentials(
 ) -> tuple[str | None, str | None, str | None]:
     """Get API key, base_url and provider_type for embeddings.
 
-    Priority:
-    1. OpenRouter env var (API_KEY_OPENROUTER) – dedicated embedding provider
-    2. Default AI provider from DB (fallback)
-    3. API_KEY_OLLAMA_CLOUD env var (last resort)
+    Thin wrapper delegating to ``app.ai.llm_client.get_api_credentials``.
+    Kept for backward compatibility with existing call sites.
     """
-    # OpenRouter is the primary embedding provider
-    if OPENROUTER_API_KEY:
-        return OPENROUTER_API_KEY, OPENROUTER_BASE_URL, 'openai'
-
-    # Fallback to DB provider
-    if db and tenant_id:
-        try:
-            from app.plugins.builtins.ai_assistant.contracts import get_default_provider
-            provider = await get_default_provider(db, tenant_id)
-            if provider and provider.api_key:
-                return provider.api_key, provider.base_url, provider.provider_type
-        except Exception:
-            logger.debug("Failed to get provider from DB, falling back to env")
-    env_key = os.environ.get('API_KEY_OLLAMA_CLOUD', '')
-    return (env_key if env_key else None), None, None
+    return await _central_get_api_credentials(db, tenant_id)
 
 
 def _build_model(model: str, provider_type: str | None) -> str:
-    """Build litellm model string with provider prefix."""
-    if provider_type:
-        model_parts = model.split("/", 1)
-        return f"{provider_type}/{model_parts[-1]}"
-    return model
+    """Build litellm model string with provider prefix.
+
+    Thin wrapper delegating to ``app.ai.llm_client.build_model``.
+    Kept for backward compatibility with existing call sites.
+    """
+    return _central_build_model(model, provider_type)
 
 
 async def generate_embedding(
@@ -77,30 +84,15 @@ async def generate_embedding(
     Returns:
         Embedding vector as list of floats.
     """
-    model = model or OPENROUTER_EMBEDDING_MODEL
-    truncated = text[:MAX_INPUT_CHARS]
-    try:
-        api_key, api_base, provider_type = await _get_api_credentials(db, tenant_id)
-        litellm_model = _build_model(model, provider_type)
-
-        litellm_kwargs: dict[str, Any] = dict(
-            model=litellm_model,
-            input=truncated,
-        )
-        if api_key:
-            litellm_kwargs["api_key"] = api_key
-        if api_base:
-            litellm_kwargs["api_base"] = api_base
-
-        # Request 768 dimensions to match DB vector(768) column
-        if 'text-embedding-3' in litellm_model:
-            litellm_kwargs['dimensions'] = EMBEDDING_DIMENSIONS
-
-        response = await litellm.aembedding(**litellm_kwargs)
-        return response.data[0]["embedding"]
-    except Exception:
-        logger.warning("Failed to generate embedding", exc_info=True)
-        return []
+    embeddings = await llm_embed(
+        texts=text,
+        model=model,
+        db=db,
+        tenant_id=tenant_id,
+    )
+    if embeddings and embeddings[0]:
+        return embeddings[0]
+    return []
 
 
 async def generate_embeddings_batch(
@@ -120,29 +112,12 @@ async def generate_embeddings_batch(
     Returns:
         List of embedding vectors.
     """
-    model = model or OPENROUTER_EMBEDDING_MODEL
-    truncated = [t[:MAX_INPUT_CHARS] for t in texts]
-    try:
-        api_key, api_base, provider_type = await _get_api_credentials(db, tenant_id)
-        litellm_model = _build_model(model, provider_type)
-
-        litellm_kwargs: dict[str, Any] = dict(
-            model=litellm_model,
-            input=truncated,
-        )
-        if api_key:
-            litellm_kwargs["api_key"] = api_key
-        if api_base:
-            litellm_kwargs["api_base"] = api_base
-
-        if 'text-embedding-3' in litellm_model:
-            litellm_kwargs['dimensions'] = EMBEDDING_DIMENSIONS
-
-        response = await litellm.aembedding(**litellm_kwargs)
-        return [d["embedding"] for d in response.data]
-    except Exception:
-        logger.warning("Failed to generate batch embeddings", exc_info=True)
-        return [[] for _ in texts]
+    return await llm_embed(
+        texts=texts,
+        model=model,
+        db=db,
+        tenant_id=tenant_id,
+    )
 
 
 async def index_entity(
@@ -201,5 +176,5 @@ async def index_entity(
         await db.commit()
         return True
     except Exception:
-        logger.exception("Failed to index entity %s/%s", entity_type, entity_id)
+        logger.warning("Failed to index entity %s/%s", entity_type, entity_id, exc_info=True)
         return False
diff --git a/app/plugins/builtins/unified_search/query_understanding.py b/app/plugins/builtins/unified_search/query_understanding.py
index e9af24c..73d8ee6 100644
--- a/app/plugins/builtins/unified_search/query_understanding.py
+++ b/app/plugins/builtins/unified_search/query_understanding.py
@@ -8,7 +8,7 @@ import logging
 import uuid
 from typing import Any
 
-import litellm
+from app.ai.llm_client import llm_complete
 from sqlalchemy.ext.asyncio import AsyncSession
 
 logger = logging.getLogger(__name__)
@@ -87,7 +87,7 @@ async def llm_analyze_query(
         api_key, api_base, provider_type = await _get_api_credentials(db, tenant_id)
         model = _build_model(DEFAULT_LLM_MODEL, provider_type)
 
-        litellm_kwargs: dict[str, Any] = dict(
+        result = await llm_complete(
             model=model,
             messages=[
                 {"role": "system", "content": QUERY_ANALYZE_SYSTEM},
@@ -96,14 +96,10 @@ async def llm_analyze_query(
             temperature=0.1,
             max_tokens=500,
             response_format={"type": "json_object"},
+            api_key=api_key,
+            api_base=api_base,
         )
-        if api_key:
-            litellm_kwargs["api_key"] = api_key
-        if api_base:
-            litellm_kwargs["api_base"] = api_base
-
-        response = await litellm.acompletion(**litellm_kwargs)
-        content = response.choices[0].message.content
+        content = result["content"]
         # Strip markdown code fences if present
         content = content.strip()
         if content.startswith("```"):
@@ -139,7 +135,7 @@ async def llm_aggregate_results(
         ]
         user_msg = json.dumps({"query": query, "results": compact})
 
-        litellm_kwargs: dict[str, Any] = dict(
+        result = await llm_complete(
             model=model,
             messages=[
                 {"role": "system", "content": RESULT_AGGREGATE_SYSTEM},
@@ -148,14 +144,10 @@ async def llm_aggregate_results(
             temperature=0.1,
             max_tokens=1000,
             response_format={"type": "json_object"},
+            api_key=api_key,
+            api_base=api_base,
         )
-        if api_key:
-            litellm_kwargs["api_key"] = api_key
-        if api_base:
-            litellm_kwargs["api_base"] = api_base
-
-        response = await litellm.acompletion(**litellm_kwargs)
-        content = response.choices[0].message.content
+        content = result["content"]
         # Strip markdown code fences if present
         content = content.strip()
         if content.startswith("```"):
diff --git a/docs/plugin-development-guide.md b/docs/plugin-development-guide.md
index 0bb4bac..91c1c07 100644
--- a/docs/plugin-development-guide.md
+++ b/docs/plugin-development-guide.md
@@ -850,4 +850,118 @@ class EventExamplePlugin(BasePlugin):
 
 ---
 
+## 7. LLM Integration
+
+LeoCRM stellt einen zentralen LLM-Client bereit über den alle LLM-Calls (Completion und Embedding) laufen. **Keine direkten `litellm.acompletion()` oder `litellm.aembedding()` Aufrufe in Plugin-Code.**
+
+### 7.1 Completion
+
+```python
+from app.ai.llm_client import llm_complete
+
+result = await llm_complete(
+    model="openai/gpt-4o",  # oder None für Default-Model
+    messages=[
+        {"role": "system", "content": "You are a helpful assistant."},
+        {"role": "user", "content": "Summarize this email."},
+    ],
+    temperature=0.3,
+    max_tokens=1000,
+    # Optional: API-Key/Base aus DB holen
+    db=db,
+    tenant_id=tenant_id,
+    # Optional: JSON-Response erzwingen
+    response_format={"type": "json_object"},
+    # Optional: Tools für Function-Calling
+    tools=[{"type": "function", "function": {...}}],
+    # Optional: Retry-Konfiguration
+    timeout=30,
+    max_retries=2,
+)
+
+content = result["content"]       # str — LLM-Response-Text
+usage = result["usage"]           # dict — {prompt_tokens, completion_tokens, total_tokens}
+cost_usd = result["cost_usd"]     # float — geschätzte Kosten
+model = result["model"]           # str — verwendetes Modell
+raw_response = result["raw_response"]  # litellm-Response-Objekt für erweiterte Nutzung
+```
+
+### 7.2 Embedding
+
+```python
+from app.ai.llm_client import llm_embed
+
+# Einzelne Embedding
+embeddings = await llm_embed(
+    texts="Text to embed",
+    model="openai/text-embedding-3-small",  # oder None für Default
+    db=db,
+    tenant_id=tenant_id,
+    dimensions=768,  # Optional, für text-embedding-3 Modelle
+)
+# → [[0.01, 0.02, ...]]
+
+# Batch-Embedding
+embeddings = await llm_embed(
+    texts=["Text 1", "Text 2", "Text 3"],
+    db=db,
+    tenant_id=tenant_id,
+)
+# → [[...], [...], [...]]
+```
+
+### 7.3 Provider-Auswahl und API-Key-Auflösung
+
+Der zentrale Client löst API-Keys automatisch aus der Datenbank (`AIProvider`-Tabelle) oder Environment-Variablen. Priorität:
+
+1. Explizit übergebener `api_key` Parameter
+2. DB-Lookup über `get_api_credentials(db, tenant_id)`
+3. Environment-Variablen (`AI_API_KEY`, `AI_API_BASE`, `AI_PROVIDER`)
+4. Mock-Mode (kein API-Key → Keyword-basierte Fallback-Antworten)
+
+```python
+from app.ai.llm_client import get_api_credentials, build_model
+
+# API-Credentials aus DB holen
+api_key, api_base, provider_type = await get_api_credentials(db, tenant_id)
+
+# Model-String bauen (provider/model)
+model = build_model("gpt-4o", provider_type)  # → "openai/gpt-4o"
+```
+
+### 7.4 Error-Handling
+
+Der zentrale Client klassifiziert Errors automatisch:
+
+- **Transient** (Timeout, Rate-Limit 429, Service-Unavailable 503) → Retry mit Exponential-Backoff
+- **Permanent** (Auth 401/403, Validation, Model-Not-Found) → Sofortiger Fehler, kein Retry
+
+```python
+try:
+    result = await llm_complete(model="openai/gpt-4o", messages=[...])
+except Exception as e:
+    # Transient errors wurden bereits retried
+    # Permanent errors kommen hier an
+    logger.error(f"LLM call failed permanently: {e}")
+```
+
+### 7.5 Cost-Tracking
+
+`llm_complete()` gibt `cost_usd` zurück — automatisch berechnet aus Token-Usage. Plugins sollen diesen Wert in ihren Cost-Tracking-Mechanismus übernehmen.
+
+```python
+result = await llm_complete(...)
+total_cost += result["cost_usd"]
+```
+
+### 7.6 Was NICHT zu tun ist
+
+- ❌ `import litellm` und direkte `litellm.acompletion()` / `litellm.aembedding()` Aufrufe
+- ❌ Eigene API-Key-Verwaltung — immer über `get_api_credentials()` oder `llm_complete(db=db, tenant_id=tenant_id)`
+- ❌ Eigene Retry-Logik — `llm_complete()` hat bereits Retry mit Backoff
+- ❌ Eigene Cost-Tracking-Logik — `llm_complete()` gibt `cost_usd` zurück
+- ❌ Eigene Provider-Auswahl — `build_model()` und `get_api_credentials()` zentralisieren das
+
+---
+
 *This document is authoritative for all plugin development at LeoCRM.*
diff --git a/tests/test_llm_client.py b/tests/test_llm_client.py
new file mode 100644
index 0000000..3538fe7
--- /dev/null
+++ b/tests/test_llm_client.py
@@ -0,0 +1,523 @@
+"""Tests for the central LLM client (app/ai/llm_client.py).
+
+Covers llm_complete(), llm_embed(), helper functions, and the
+LLMClient backward-compatibility class. All LiteLLM calls are mocked —
+no real API requests are made.
+"""
+
+from __future__ import annotations
+
+import asyncio
+from typing import Any
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+from app.ai.llm_client import (
+    BASE_BACKOFF_SECONDS,
+    DEFAULT_MAX_RETRIES,
+    LLMClient,
+    LLMResponse,
+    _classify_error,
+    _extract_cost_usd,
+    _extract_usage,
+    build_model,
+    get_llm_client,
+    llm_complete,
+    llm_embed,
+    reset_llm_client,
+)
+
+
+# ──────────────────────────────────────────────────────────────────────────
+# Helpers
+# ──────────────────────────────────────────────────────────────────────────
+
+
+def _mock_completion_response(
+    content: str = "Hello!",
+    prompt_tokens: int = 10,
+    completion_tokens: int = 5,
+) -> MagicMock:
+    """Build a fake LiteLLM completion response object."""
+    resp = MagicMock()
+    resp.choices = [MagicMock()]
+    resp.choices[0].message.content = content
+    resp.usage = MagicMock(
+        prompt_tokens=prompt_tokens,
+        completion_tokens=completion_tokens,
+        total_tokens=prompt_tokens + completion_tokens,
+    )
+    return resp
+
+
+def _mock_embedding_response(count: int = 1, dims: int = 4) -> MagicMock:
+    """Build a fake LiteLLM embedding response object."""
+    resp = MagicMock()
+    resp.data = [{"embedding": [0.1] * dims} for _ in range(count)]
+    return resp
+
+
+# ──────────────────────────────────────────────────────────────────────────
+# TestLLMComplete
+# ──────────────────────────────────────────────────────────────────────────
+
+
+class TestLLMComplete:
+    """Tests for llm_complete() — mock mode, parameter pass-through, errors."""
+
+    @pytest.mark.asyncio
+    async def test_basic_completion_no_api_key(self) -> None:
+        """llm_complete() without api_key should still call litellm.acompletion."""
+        mock_resp = _mock_completion_response(content="Hi there")
+        with patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion:
+            mock_acompletion.return_value = mock_resp
+            result = await llm_complete(
+                model="gpt-4o",
+                messages=[{"role": "user", "content": "hello"}],
+                api_key=None,
+            )
+        assert result["content"] == "Hi there"
+        assert result["model"] == "gpt-4o"
+        assert result["usage"]["prompt_tokens"] == 10
+        assert result["usage"]["completion_tokens"] == 5
+        assert result["usage"]["total_tokens"] == 15
+        # api_key should not be in kwargs
+        call_kwargs = mock_acompletion.call_args.kwargs
+        assert "api_key" not in call_kwargs
+
+    @pytest.mark.asyncio
+    async def test_response_format_passed_through(self) -> None:
+        """response_format parameter is passed to litellm.acompletion."""
+        mock_resp = _mock_completion_response(content='{"key": "value"}')
+        rf = {"type": "json_object"}
+        with patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion:
+            mock_acompletion.return_value = mock_resp
+            await llm_complete(
+                model="gpt-4o",
+                messages=[{"role": "user", "content": "return json"}],
+                response_format=rf,
+                api_key="test-key",
+            )
+        call_kwargs = mock_acompletion.call_args.kwargs
+        assert call_kwargs["response_format"] == rf
+
+    @pytest.mark.asyncio
+    async def test_tools_parameter_passed_through(self) -> None:
+        """tools parameter is passed to litellm.acompletion."""
+        mock_resp = _mock_completion_response(content="ok")
+        tools = [{"type": "function", "function": {"name": "get_weather"}}]
+        with patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion:
+            mock_acompletion.return_value = mock_resp
+            await llm_complete(
+                model="gpt-4o",
+                messages=[{"role": "user", "content": "weather?"}],
+                tools=tools,
+                api_key="test-key",
+            )
+        call_kwargs = mock_acompletion.call_args.kwargs
+        assert call_kwargs["tools"] == tools
+
+    @pytest.mark.asyncio
+    async def test_timeout_transient_error_retries(self) -> None:
+        """Timeout error is classified as transient and retried."""
+        mock_resp = _mock_completion_response(content="success")
+        with (
+            patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion,
+            patch("app.ai.llm_client.asyncio.sleep", new_callable=AsyncMock) as mock_sleep,
+        ):
+            mock_acompletion.side_effect = [asyncio.TimeoutError("Request timed out"), mock_resp]
+            result = await llm_complete(
+                model="gpt-4o",
+                messages=[{"role": "user", "content": "hi"}],
+                api_key="test-key",
+                max_retries=2,
+            )
+        assert result["content"] == "success"
+        assert mock_acompletion.call_count == 2
+        assert mock_sleep.call_count == 1  # one backoff before retry
+
+    @pytest.mark.asyncio
+    async def test_rate_limit_429_transient_retries_with_backoff(self) -> None:
+        """429 rate-limit error is transient and retried with exponential backoff."""
+        mock_resp = _mock_completion_response(content="ok")
+        with (
+            patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion,
+            patch("app.ai.llm_client.asyncio.sleep", new_callable=AsyncMock) as mock_sleep,
+        ):
+            mock_acompletion.side_effect = [Exception("Rate limit exceeded: 429"), mock_resp]
+            result = await llm_complete(
+                model="gpt-4o",
+                messages=[{"role": "user", "content": "hi"}],
+                api_key="test-key",
+                max_retries=2,
+            )
+        assert result["content"] == "ok"
+        assert mock_acompletion.call_count == 2
+        # First backoff = BASE_BACKOFF_SECONDS * 2^0 = 1.0
+        mock_sleep.assert_called_once_with(BASE_BACKOFF_SECONDS * 1)
+
+    @pytest.mark.asyncio
+    async def test_auth_error_permanent_no_retry(self) -> None:
+        """401 auth error is permanent — no retry, immediate raise."""
+        auth_exc = Exception("Authentication error: 401 Unauthorized")
+        with (
+            patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion,
+            patch("app.ai.llm_client.asyncio.sleep", new_callable=AsyncMock) as mock_sleep,
+        ):
+            mock_acompletion.side_effect = auth_exc
+            with pytest.raises(Exception, match="401"):
+                await llm_complete(
+                    model="gpt-4o",
+                    messages=[{"role": "user", "content": "hi"}],
+                    api_key="bad-key",
+                    max_retries=3,
+                )
+        assert mock_acompletion.call_count == 1  # no retry
+        assert mock_sleep.call_count == 0
+
+    @pytest.mark.asyncio
+    async def test_max_retries_zero_no_retry(self) -> None:
+        """max_retries=0 means no retry on transient error."""
+        timeout_exc = asyncio.TimeoutError("timed out")
+        with (
+            patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion,
+            patch("app.ai.llm_client.asyncio.sleep", new_callable=AsyncMock) as mock_sleep,
+        ):
+            mock_acompletion.side_effect = timeout_exc
+            with pytest.raises(asyncio.TimeoutError):
+                await llm_complete(
+                    model="gpt-4o",
+                    messages=[{"role": "user", "content": "hi"}],
+                    api_key="test-key",
+                    max_retries=0,
+                )
+        assert mock_acompletion.call_count == 1
+        assert mock_sleep.call_count == 0
+
+    @pytest.mark.asyncio
+    async def test_max_retries_2_then_final_error(self) -> None:
+        """max_retries=2 → 2 retries (3 total attempts) then final error."""
+        timeout_exc = asyncio.TimeoutError("timed out")
+        with (
+            patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion,
+            patch("app.ai.llm_client.asyncio.sleep", new_callable=AsyncMock) as mock_sleep,
+        ):
+            mock_acompletion.side_effect = timeout_exc
+            with pytest.raises(asyncio.TimeoutError):
+                await llm_complete(
+                    model="gpt-4o",
+                    messages=[{"role": "user", "content": "hi"}],
+                    api_key="test-key",
+                    max_retries=2,
+                )
+        # 1 initial + 2 retries = 3 total calls
+        assert mock_acompletion.call_count == 3
+        assert mock_sleep.call_count == 2
+
+    @pytest.mark.asyncio
+    async def test_provider_prefix_applied(self) -> None:
+        """provider parameter causes build_model prefix to be applied."""
+        mock_resp = _mock_completion_response(content="ok")
+        with patch("app.ai.llm_client.litellm.acompletion", new_callable=AsyncMock) as mock_acompletion:
+            mock_acompletion.return_value = mock_resp
+            await llm_complete(
+                model="gpt-4o",
+                messages=[{"role": "user", "content": "hi"}],
+                provider="anthropic",
+                api_key="test-key",
+            )
+        call_kwargs = mock_acompletion.call_args.kwargs
+        assert call_kwargs["model"] == "anthropic/gpt-4o"
+
+
+# ──────────────────────────────────────────────────────────────────────────
+# TestLLMEmbed
+# ──────────────────────────────────────────────────────────────────────────
+
+
+class TestLLMEmbed:
+    """Tests for llm_embed() — mock mode, single/batch, dimensions."""
+
+    @pytest.mark.asyncio
+    async def test_embed_single_text(self) -> None:
+        """llm_embed() with a single text returns list[list[float]]."""
+        mock_resp = _mock_embedding_response(count=1, dims=4)
+        with patch("app.ai.llm_client.litellm.aembedding", new_callable=AsyncMock) as mock_aembedding:
+            mock_aembedding.return_value = mock_resp
+            result = await llm_embed(
+                texts="hello world",
+                api_key="test-key",
+                model="openai/text-embedding-3-small",
+            )
+        assert isinstance(result, list)
+        assert len(result) == 1
+        assert isinstance(result[0], list)
+        assert all(isinstance(v, float) for v in result[0])
+
+    @pytest.mark.asyncio
+    async def test_embed_batch_texts(self) -> None:
+        """llm_embed() with a list of texts returns batch embeddings."""
+        mock_resp = _mock_embedding_response(count=3, dims=4)
+        with patch("app.ai.llm_client.litellm.aembedding", new_callable=AsyncMock) as mock_aembedding:
+            mock_aembedding.return_value = mock_resp
+            result = await llm_embed(
+                texts=["text one", "text two", "text three"],
+                api_key="test-key",
+                model="openai/text-embedding-3-small",
+            )
+        assert len(result) == 3
+        assert all(len(emb) == 4 for emb in result)
+
+    @pytest.mark.asyncio
+    async def test_embed_dimensions_passed_through(self) -> None:
+        """dimensions parameter is passed to litellm.aembedding for text-embedding-3 models."""
+        mock_resp = _mock_embedding_response(count=1, dims=768)
+        with patch("app.ai.llm_client.litellm.aembedding", new_callable=AsyncMock) as mock_aembedding:
+            mock_aembedding.return_value = mock_resp
+            await llm_embed(
+                texts="hello",
+                api_key="test-key",
+                model="openai/text-embedding-3-small",
+                dimensions=768,
+            )
+        call_kwargs = mock_aembedding.call_args.kwargs
+        assert call_kwargs["dimensions"] == 768
+
+    @pytest.mark.asyncio
+    async def test_embed_empty_list_returns_empty(self) -> None:
+        """llm_embed() with empty list returns empty list without calling API."""
+        with patch("app.ai.llm_client.litellm.aembedding", new_callable=AsyncMock) as mock_aembedding:
+            result = await llm_embed(texts=[], api_key="test-key")
+        assert result == []
+        assert mock_aembedding.call_count == 0
+
+    @pytest.mark.asyncio
+    async def test_embed_failure_returns_empty_vectors(self) -> None:
+        """On API failure, llm_embed() returns empty vectors for each input text."""
+        with patch("app.ai.llm_client.litellm.aembedding", new_callable=AsyncMock) as mock_aembedding:
+            mock_aembedding.side_effect = Exception("connection refused")
+            result = await llm_embed(
+                texts=["a", "b"],
+                api_key="test-key",
+                model="openai/text-embedding-3-small",
+            )
+        assert result == [[], []]
+
+
+# ──────────────────────────────────────────────────────────────────────────
+# TestHelpers
+# ──────────────────────────────────────────────────────────────────────────
+
+
+class TestHelpers:
+    """Tests for build_model, _classify_error, _extract_cost_usd, _extract_usage."""
+
+    def test_build_model_with_provider(self) -> None:
+        """build_model() prepends provider prefix, stripping any existing prefix."""
+        assert build_model("gpt-4o", "openai") == "openai/gpt-4o"
+        assert build_model("openai/gpt-4o", "anthropic") == "anthropic/gpt-4o"
+        assert build_model("claude-3-sonnet", "anthropic") == "anthropic/claude-3-sonnet"
+
+    def test_build_model_without_provider(self) -> None:
+        """build_model() returns model unchanged when provider is None."""
+        assert build_model("gpt-4o", None) == "gpt-4o"
+        assert build_model("openai/gpt-4o", None) == "openai/gpt-4o"
+
+    def test_build_model_empty_provider(self) -> None:
+        """build_model() with empty string provider returns model unchanged."""
+        assert build_model("gpt-4o", "") == "gpt-4o"
+
+    def test_classify_error_transient_timeout(self) -> None:
+        """TimeoutError is classified as transient."""
+        assert _classify_error(asyncio.TimeoutError("timed out")) == "transient"
+        assert _classify_error(TimeoutError("operation timed out")) == "transient"
+
+    def test_classify_error_transient_rate_limit(self) -> None:
+        """Rate limit / 429 / 503 errors are transient."""
+        assert _classify_error(Exception("rate limit exceeded")) == "transient"
+        assert _classify_error(Exception("429 Too Many Requests")) == "transient"
+        assert _classify_error(Exception("503 service unavailable")) == "transient"
+        assert _classify_error(Exception("502 bad gateway")) == "transient"
+        assert _classify_error(Exception("504 gateway timeout")) == "transient"
+
+    def test_classify_error_permanent_auth(self) -> None:
+        """Auth / 401 / 403 errors are permanent."""
+        assert _classify_error(Exception("authentication failed")) == "permanent"
+        assert _classify_error(Exception("401 Unauthorized")) == "permanent"
+        assert _classify_error(Exception("403 Forbidden")) == "permanent"
+        assert _classify_error(Exception("invalid api key")) == "permanent"
+        assert _classify_error(Exception("invalid_api_key")) == "permanent"
+
+    def test_classify_error_permanent_validation(self) -> None:
+        """Validation / 400 / model_not_found errors are permanent."""
+        assert _classify_error(Exception("invalid_request")) == "permanent"
+        assert _classify_error(Exception("400 bad request")) == "permanent"
+        assert _classify_error(Exception("model_not_found")) == "permanent"
+
+    def test_classify_error_unknown_defaults_transient(self) -> None:
+        """Unknown errors default to transient (safe to retry)."""
+        assert _classify_error(Exception("something weird happened")) == "transient"
+        assert _classify_error(ValueError("unexpected value")) == "transient"
+
+    def test_classify_error_permanent_takes_priority(self) -> None:
+        """If both permanent and transient keywords match, permanent wins."""
+        # Contains both 'timeout' (transient) and '401' (permanent)
+        exc = Exception("timeout during authentication: 401")
+        assert _classify_error(exc) == "permanent"
+
+    def test_extract_cost_usd_success(self) -> None:
+        """_extract_cost_usd() returns cost from litellm.completion_cost."""
+        resp = MagicMock()
+        with patch("app.ai.llm_client.litellm.completion_cost", return_value=0.0025) as mock_cost:
+            cost = _extract_cost_usd(resp, "openai/gpt-4o")
+        assert cost == pytest.approx(0.0025)
+        mock_cost.assert_called_once_with(resp)
+
+    def test_extract_cost_usd_failure_returns_zero(self) -> None:
+        """_extract_cost_usd() returns 0.0 when litellm.completion_cost fails."""
+        resp = MagicMock()
+        with patch("app.ai.llm_client.litellm.completion_cost", side_effect=Exception("no cost data")):
+            cost = _extract_cost_usd(resp, "openai/gpt-4o")
+        assert cost == 0.0
+
+    def test_extract_cost_usd_none_returns_zero(self) -> None:
+        """_extract_cost_usd() returns 0.0 when completion_cost returns None."""
+        resp = MagicMock()
+        with patch("app.ai.llm_client.litellm.completion_cost", return_value=None):
+            cost = _extract_cost_usd(resp, "openai/gpt-4o")
+        assert cost == 0.0
+
+    def test_extract_usage_with_tokens(self) -> None:
+        """_extract_usage() returns prompt, completion, total tokens from response."""
+        resp = MagicMock()
+        resp.usage = MagicMock(prompt_tokens=50, completion_tokens=30, total_tokens=80)
+        usage = _extract_usage(resp)
+        assert usage == {"prompt_tokens": 50, "completion_tokens": 30, "total_tokens": 80}
+
+    def test_extract_usage_no_usage_attr(self) -> None:
+        """_extract_usage() returns zeros when response has no usage attribute."""
+        resp = MagicMock()
+        resp.usage = None
+        usage = _extract_usage(resp)
+        assert usage == {"prompt_tokens": 0, "completion_tokens": 0, "total_tokens": 0}
+
+    def test_extract_usage_missing_total(self) -> None:
+        """_extract_usage() computes total_tokens when not present."""
+        resp = MagicMock()
+        resp.usage = MagicMock(prompt_tokens=20, completion_tokens=10, total_tokens=0)
+        # total_tokens is 0 (falsy) → should fall back to prompt + completion
+        usage = _extract_usage(resp)
+        assert usage["prompt_tokens"] == 20
+        assert usage["completion_tokens"] == 10
+        assert usage["total_tokens"] == 30  # 20 + 10
+
+
+# ──────────────────────────────────────────────────────────────────────────
+# TestLLMClientCompat
+# ──────────────────────────────────────────────────────────────────────────
+
+
+class TestLLMClientCompat:
+    """Tests for LLMClient class, get_llm_client(), reset_llm_client()."""
+
+    @pytest.mark.asyncio
+    async def test_mock_mode_calls_mock_generate(self) -> None:
+        """LLMClient in mock mode calls _mock_generate (no API call)."""
+        client = LLMClient(model=None, api_key=None)
+        assert client.is_mock is True
+
+        with patch.object(client, "_mock_generate", new_callable=AsyncMock) as mock_mock_gen:
+            mock_mock_gen.return_value = LLMResponse(
+                message="mocked", proposed_actions=[], confidence=0.5
+            )
+            result = await client.generate("create a contact")
+        mock_mock_gen.assert_called_once()
+        assert result.message == "mocked"
+
+    @pytest.mark.asyncio
+    async def test_mock_mode_keyword_matching(self) -> None:
+        """LLLMClient mock mode maps keywords to actions via action_mapper."""
+        client = LLMClient(model=None, api_key=None)
+        result = await client.generate("create a new contact named John")
+        assert isinstance(result, LLMResponse)
+        assert len(result.proposed_actions) > 0
+        assert result.proposed_actions[0]["method"] == "POST"
+
+    @pytest.mark.asyncio
+    async def test_mock_mode_no_match(self) -> None:
+        """LLMClient mock mode returns empty actions for unrecognized query."""
+        client = LLMClient(model=None, api_key=None)
+        result = await client.generate("xyzzy nonsense")
+        assert result.proposed_actions == []
+        assert result.confidence < 0.5
+
+    @pytest.mark.asyncio
+    async def test_api_mode_calls_llm_complete(self) -> None:
+        """LLMClient in API mode calls llm_complete (mocked)."""
+        client = LLMClient(model="gpt-4o", api_key="test-key")
+        assert client.is_mock is False
+
+        llm_result = {
+            "content": '{"message": "ok", "proposed_actions": [], "confidence": 0.9}',
+            "usage": {"prompt_tokens": 10, "completion_tokens": 5, "total_tokens": 15},
+            "cost_usd": 0.001,
+            "model": "openai/gpt-4o",
+            "raw_response": MagicMock(),
+        }
+        with patch("app.ai.llm_client.llm_complete", new_callable=AsyncMock) as mock_llm_complete:
+            mock_llm_complete.return_value = llm_result
+            result = await client.generate("list all contacts")
+        mock_llm_complete.assert_called_once()
+        assert result.message == "ok"
+        assert result.confidence == 0.9
+
+    @pytest.mark.asyncio
+    async def test_api_mode_fallback_on_error(self) -> None:
+        """LLMClient API mode falls back to empty actions on API error."""
+        client = LLMClient(model="gpt-4o", api_key="test-key")
+        with patch("app.ai.llm_client.llm_complete", new_callable=AsyncMock) as mock_llm_complete:
+            mock_llm_complete.side_effect = Exception("API down")
+            result = await client.generate("list contacts")
+        assert result.proposed_actions == []
+        assert result.confidence == 0.1
+        assert "API call failed" in result.message
+
+    def test_get_llm_client_singleton(self) -> None:
+        """get_llm_client() returns the same instance on repeated calls."""
+        reset_llm_client()
+        client1 = get_llm_client()
+        client2 = get_llm_client()
+        assert client1 is client2
+        assert isinstance(client1, LLMClient)
+
+    def test_reset_llm_client_clears_instance(self) -> None:
+        """reset_llm_client() clears the singleton, next get_llm_client() returns new instance."""
+        reset_llm_client()
+        client1 = get_llm_client()
+        reset_llm_client()
+        client2 = get_llm_client()
+        assert client1 is not client2
+
+    def test_llm_client_default_mock_mode(self) -> None:
+        """LLMClient() with no args and no env vars defaults to mock mode."""
+        with patch.dict("os.environ", {}, clear=False):
+            # Ensure AI_MODEL and AI_API_KEY are not set
+            import os
+            env_copy = dict(os.environ)
+            env_copy.pop("AI_MODEL", None)
+            env_copy.pop("AI_API_KEY", None)
+            with patch.dict(os.environ, env_copy, clear=True):
+                client = LLMClient()
+                assert client.is_mock is True
+
+    def test_llm_client_api_mode_with_model_and_key(self) -> None:
+        """LLMClient() with model and api_key is not in mock mode."""
+        client = LLMClient(model="gpt-4o", api_key="sk-test")
+        assert client.is_mock is False
+
+    def test_llm_response_to_dict(self) -> None:
+        """LLMResponse.to_dict() returns correct structure."""
+        resp = LLMResponse(message="hello", proposed_actions=[{"method": "GET"}], confidence=0.9)
+        d = resp.to_dict()
+        assert d == {"message": "hello", "proposed_actions": [{"method": "GET"}], "confidence": 0.9}