Initial commit

opc/llm/provider.py

@@ -0,0 +1,897 @@
+"""LLM provider layer built on LiteLLM for unified model access."""
+
+from __future__ import annotations
+
+import base64
+import hashlib
+import json
+import os
+from pathlib import Path
+from typing import Any, AsyncIterator
+from urllib.parse import urlparse
+
+from opc.core.windows_ssl import sanitize_windows_sslkeylogfile
+
+sanitize_windows_sslkeylogfile()
+
+import litellm
+from loguru import logger
+
+from opc.core.attachment_content import attachment_suffix
+from opc.core.attachment_store import AttachmentRef
+from opc.core.config import LLMConfig
+from opc.core.models import ModelCapabilitySet, RuntimeLLMEvent
+
+litellm.suppress_debug_info = True
+litellm.drop_params = True
+
+_MULTIMODAL_MODEL_HINTS = (
+    "gpt-4.1",
+    "gpt-4o",
+    "gpt-4.5",
+    "gpt-5",
+    "o1",
+    "o3",
+    "o4",
+    "claude-3",
+    "claude-sonnet-4",
+    "claude-opus-4",
+    "gemini",
+    "pixtral",
+    "llava",
+    "qwen-vl",
+    "qwen2-vl",
+    "qwen2.5-vl",
+    "internvl",
+    "minicpm-v",
+    "glm-4v",
+)
+
+_DOCUMENT_MODEL_HINTS = (
+    "gpt-4.1",
+    "gpt-4o",
+    "gpt-4.5",
+    "gpt-5",
+    "claude-3",
+    "claude-sonnet-4",
+    "claude-opus-4",
+    "gemini",
+)
+
+_VIDEO_MODEL_HINTS = (
+    "gemini",
+    "veo",
+    "video",
+)
+
+_TOOL_PROTOCOL_ERROR_HINTS = (
+    "no tool output found for function call",
+    "no tool output found",
+    "messages with role 'tool' must be a response to a preceding message with 'tool_calls'",
+    "assistant message with tool_calls",
+    "tool_calls must be followed by tool messages",
+    "missing tool response",
+    "missing tool output",
+    "tool_call_id",
+)
+
+
+def _normalized_model_name(model: str) -> str:
+    if "/" in model:
+        return model.split("/", 1)[1].strip().lower()
+    return model.strip().lower()
+
+
+_CONTEXT_WINDOW_OVERRIDES: tuple[tuple[str, int], ...] = (
+    ("gpt-5.4-pro", 1_050_000),
+    ("gpt-5.4-mini", 400_000),
+    ("gpt-5.4-nano", 400_000),
+    ("gpt-5.4", 1_050_000),
+    ("gpt-5-pro", 400_000),
+    ("gpt-5", 400_000),
+)
+
+
+_POE_CONTEXT_WINDOW_OVERRIDES: tuple[tuple[str, int], ...] = (
+    ("claude-sonnet-4.5", 64_000),
+    ("claude-sonnet-4-5", 64_000),
+)
+
+
+def _context_window_override(model: str) -> int | None:
+    normalized = _normalized_model_name(model)
+    for prefix, window in _CONTEXT_WINDOW_OVERRIDES:
+        if normalized == prefix or normalized.startswith(f"{prefix}-"):
+            return window
+    return None
+
+
+def _poe_context_window_override(model: str) -> int | None:
+    normalized = _normalized_model_name(model)
+    for prefix, window in _POE_CONTEXT_WINDOW_OVERRIDES:
+        if normalized == prefix or normalized.startswith(f"{prefix}-"):
+            return window
+    return None
+
+
+def _is_official_openai_base(api_base: str | None) -> bool:
+    normalized = str(api_base or "").strip()
+    if not normalized:
+        return True
+    try:
+        parsed = urlparse(normalized)
+    except Exception:
+        return False
+    hostname = (parsed.hostname or "").strip().lower()
+    return hostname in {"api.openai.com", "openai.com"}
+
+
+def _is_poe_base(api_base: str | None) -> bool:
+    normalized = str(api_base or "").strip()
+    if not normalized:
+        return False
+    try:
+        parsed = urlparse(normalized)
+    except Exception:
+        return False
+    hostname = (parsed.hostname or "").strip().lower()
+    return hostname == "api.poe.com"
+
+
+def _looks_like_multimodal_model(model: str) -> bool:
+    normalized = _normalized_model_name(model)
+    if any(hint in normalized for hint in _MULTIMODAL_MODEL_HINTS):
+        return True
+    return normalized.endswith("-vl") or "-vl-" in normalized or "_vl" in normalized
+
+
+def _looks_like_document_capable_model(model: str) -> bool:
+    normalized = _normalized_model_name(model)
+    return any(hint in normalized for hint in _DOCUMENT_MODEL_HINTS)
+
+
+def _looks_like_video_capable_model(model: str) -> bool:
+    normalized = _normalized_model_name(model)
+    return any(hint in normalized for hint in _VIDEO_MODEL_HINTS)
+
+
+def _parse_tool_arguments(tool_name: str, arguments: Any) -> tuple[Any, str | None, str | None]:
+    """Parse tool-call arguments and preserve failures for downstream recovery."""
+    if not isinstance(arguments, str):
+        return arguments, None, None
+
+    raw = arguments
+    try:
+        parsed = json.loads(raw)
+        return parsed, raw, None
+    except json.JSONDecodeError as e:
+        snippet = raw[:500].replace("\n", "\\n")
+        error = f"Invalid tool arguments JSON for `{tool_name}`: {e.msg} at char {e.pos}"
+        logger.warning(f"{error}. Raw snippet: {snippet}")
+        return raw, raw, error
+
+
+class LLMProvider:
+    """Unified LLM interface via LiteLLM supporting tool calls."""
+
+    # Well-known provider API-key env vars that litellm reads directly when no
+    # explicit api_key is passed. Used only by ``has_credentials()`` to avoid a
+    # false "no credentials" verdict for env-based setups. Missing a provider
+    # here just preserves the old behavior (a real LLM attempt), never a wrong
+    # skip of a working key.
+    _CREDENTIAL_ENV_VARS = (
+        "OPENAI_API_KEY",
+        "ANTHROPIC_API_KEY",
+        "OPENROUTER_API_KEY",
+        "AZURE_API_KEY",
+        "AZURE_OPENAI_API_KEY",
+        "GEMINI_API_KEY",
+        "GOOGLE_API_KEY",
+        "MISTRAL_API_KEY",
+        "GROQ_API_KEY",
+        "DEEPSEEK_API_KEY",
+        "TOGETHERAI_API_KEY",
+        "ARK_API_KEY",
+    )
+
+    def __init__(self, config: LLMConfig, opc_home: Path | None = None) -> None:
+        self.config = config
+        self.opc_home = opc_home
+        self._total_tokens_in = 0
+        self._total_tokens_out = 0
+        self._total_cost = 0.0
+
+        self._api_key = config.api_key or (
+            os.environ.get(config.api_key_env) if config.api_key_env else None
+        ) or None
+        self._api_base = config.api_base or None
+
+    def has_credentials(self) -> bool:
+        """Whether an LLM call can plausibly authenticate.
+
+        True when a key is configured (``api_key`` / ``api_key_env``) or a
+        well-known provider env var is present. False only when no credential
+        is found anywhere — callers use that to skip LLM work that would
+        certainly fail (e.g. native agent selection when an external agent can
+        run the task instead). A False at worst degrades to rule-based behavior,
+        which stays functional; it never blocks execution.
+        """
+        if self._api_key:
+            return True
+        return any(os.environ.get(var) for var in self._CREDENTIAL_ENV_VARS)
+
+    @property
+    def stats(self) -> dict[str, Any]:
+        return {
+            "tokens_in": self._total_tokens_in,
+            "tokens_out": self._total_tokens_out,
+            "estimated_cost": self._total_cost,
+        }
+
+    def _select_model(self, task_type: str | None = None) -> str:
+        if task_type and task_type in self.config.routing:
+            return self.config.routing[task_type]
+        return self.config.default_model
+
+    def _config_context_window_override(self, model: str) -> int | None:
+        """User-configured context window for models litellm cannot map.
+
+        Per-model overrides win over the scalar default. Both come from
+        ``LLMConfig`` so proxy/self-hosted models (doubao, minimax, glm, …)
+        can report a real context window to the usage ring and compaction.
+        """
+        per_model = getattr(self.config, "context_window_overrides", None) or {}
+        normalized = _normalized_model_name(model)
+        for key, window in per_model.items():
+            candidate = _normalized_model_name(str(key))
+            if candidate and (normalized == candidate or normalized.startswith(f"{candidate}-")):
+                try:
+                    value = int(window)
+                except (TypeError, ValueError):
+                    continue
+                if value > 0:
+                    return value
+        try:
+            scalar = int(getattr(self.config, "context_window", 0) or 0)
+        except (TypeError, ValueError):
+            scalar = 0
+        return scalar if scalar > 0 else None
+
+    def get_context_window(self, task_type: str | None = None, model: str | None = None) -> int | None:
+        resolved_model = model or self._select_model(task_type)
+        config_override = self._config_context_window_override(resolved_model)
+        if config_override is not None:
+            return config_override
+        poe_override = _poe_context_window_override(resolved_model) if _is_poe_base(self._api_base) else None
+        if poe_override is not None:
+            return poe_override
+        override = _context_window_override(resolved_model) if _is_official_openai_base(self._api_base) else None
+        if override is not None:
+            return override
+        try:
+            limit = litellm.get_max_tokens(resolved_model)
+            return int(limit) if limit else None
+        except Exception as e:
+            logger.warning(f"Unable to resolve context window for model={resolved_model}: {e}")
+            return None
+
+    def count_input_tokens(
+        self,
+        messages: list[dict[str, Any]],
+        tools: list[dict[str, Any]] | None = None,
+        task_type: str | None = None,
+        model: str | None = None,
+    ) -> int | None:
+        resolved_model = model or self._select_model(task_type)
+        try:
+            return int(litellm.token_counter(
+                model=resolved_model,
+                messages=messages,
+                tools=tools,
+            ))
+        except Exception as e:
+            logger.warning(f"Unable to count prompt tokens for model={resolved_model}: {e}")
+            return None
+
+    def count_text_tokens(
+        self,
+        text: str,
+        task_type: str | None = None,
+        model: str | None = None,
+    ) -> int | None:
+        resolved_model = model or self._select_model(task_type)
+        try:
+            return int(litellm.token_counter(
+                model=resolved_model,
+                text=text,
+            ))
+        except Exception as e:
+            logger.warning(f"Unable to count text tokens for model={resolved_model}: {e}")
+            return None
+
+    def get_capabilities(
+        self,
+        task_type: str | None = None,
+        model: str | None = None,
+    ) -> ModelCapabilitySet:
+        resolved_model = model or self._select_model(task_type)
+        normalized = _normalized_model_name(resolved_model)
+        provider_family = resolved_model.split("/", 1)[0].strip().lower() if "/" in resolved_model else ""
+        supports_thinking = any(hint in normalized for hint in ("o1", "o3", "o4", "gpt-5", "claude", "reason"))
+        return ModelCapabilitySet(
+            model=resolved_model,
+            supports_streaming=True,
+            supports_tool_calling=True,
+            supports_streaming_tool_calls=True,
+            supports_thinking=supports_thinking,
+            supports_multimodal=_looks_like_multimodal_model(resolved_model),
+            supports_documents=_looks_like_document_capable_model(resolved_model),
+            supports_video=_looks_like_video_capable_model(resolved_model),
+            provider_family=provider_family,
+            metadata={
+                "api_base": self._api_base or "",
+            },
+        )
+
+    def build_cache_fingerprint(
+        self,
+        *,
+        messages: list[dict[str, Any]],
+        tools: list[dict[str, Any]] | None = None,
+        task_type: str | None = None,
+        model: str | None = None,
+        extra: dict[str, Any] | None = None,
+    ) -> str:
+        resolved_model = model or self._select_model(task_type)
+        payload = {
+            "model": resolved_model,
+            "messages": messages,
+            "tools": tools or [],
+            "extra": extra or {},
+        }
+        raw = json.dumps(payload, ensure_ascii=False, sort_keys=True, default=str)
+        return hashlib.sha256(raw.encode("utf-8")).hexdigest()
+
+    def is_context_overflow_error(self, error: Exception) -> bool:
+        if isinstance(error, litellm.exceptions.ContextWindowExceededError):
+            return True
+        message = str(error).lower()
+        keywords = (
+            "context window",
+            "context length",
+            "maximum context length",
+            "prompt is too long",
+            "too many tokens",
+            "context_length_exceeded",
+            "token limit exceeded",
+        )
+        return any(keyword in message for keyword in keywords)
+
+    def is_tool_protocol_error(self, error: Exception) -> bool:
+        message = str(error).lower()
+        return any(hint in message for hint in _TOOL_PROTOCOL_ERROR_HINTS)
+
+    @staticmethod
+    def sanitize_tool_call_history(messages: list[dict[str, Any]]) -> list[dict[str, Any]]:
+        """Drop incomplete or stray assistant/tool tool-call transcripts."""
+        sanitized: list[dict[str, Any]] = []
+        pending_ids: list[str] = []
+        buffered_block: list[dict[str, Any]] = []
+
+        def _copy_message(message: dict[str, Any]) -> dict[str, Any]:
+            cloned = dict(message)
+            if isinstance(message.get("tool_calls"), list):
+                cloned["tool_calls"] = [dict(item) for item in message["tool_calls"]]
+            return cloned
+
+        for message in messages:
+            role = str(message.get("role", "") or "").strip()
+            if not pending_ids:
+                if role == "assistant" and isinstance(message.get("tool_calls"), list) and message["tool_calls"]:
+                    ids = [
+                        str(item.get("id", "") or "").strip()
+                        for item in message["tool_calls"]
+                        if isinstance(item, dict) and str(item.get("id", "") or "").strip()
+                    ]
+                    if not ids:
+                        continue
+                    buffered_block = [_copy_message(message)]
+                    pending_ids = ids
+                    continue
+                if role == "tool":
+                    continue
+                sanitized.append(_copy_message(message))
+                continue
+
+            if role == "tool":
+                tool_call_id = str(message.get("tool_call_id", "") or "").strip()
+                if tool_call_id and tool_call_id in pending_ids:
+                    buffered_block.append(_copy_message(message))
+                    pending_ids = [item for item in pending_ids if item != tool_call_id]
+                    if not pending_ids:
+                        sanitized.extend(buffered_block)
+                        buffered_block = []
+                continue
+
+            if role == "assistant" and isinstance(message.get("tool_calls"), list) and message["tool_calls"]:
+                ids = [
+                    str(item.get("id", "") or "").strip()
+                    for item in message["tool_calls"]
+                    if isinstance(item, dict) and str(item.get("id", "") or "").strip()
+                ]
+                buffered_block = [_copy_message(message)] if ids else []
+                pending_ids = ids
+                continue
+
+            buffered_block = []
+            pending_ids = []
+            sanitized.append(_copy_message(message))
+
+        return sanitized
+
+    def prepare_user_message_content(
+        self,
+        content: str,
+        *,
+        attachment_refs: list[dict[str, Any]] | None = None,
+        task_type: str | None = None,
+    ) -> str | list[dict[str, Any]]:
+        text = str(content or "")
+        refs = list(attachment_refs or [])
+        if not refs:
+            return text
+
+        model = self._select_model(task_type)
+        parts = self._build_direct_attachment_parts(model, refs)
+        if not parts:
+            return text
+
+        content_parts: list[dict[str, Any]] = []
+        if text:
+            content_parts.append({"type": "text", "text": text})
+        content_parts.extend(parts)
+        return content_parts
+
+    async def chat(
+        self,
+        messages: list[dict[str, Any]],
+        tools: list[dict[str, Any]] | None = None,
+        task_type: str | None = None,
+        temperature: float | None = None,
+        max_tokens: int | None = None,
+        **kwargs: Any,
+    ) -> dict[str, Any]:
+        model = self._select_model(task_type)
+        temp = temperature if temperature is not None else self.config.temperature
+        max_tok = max_tokens if max_tokens is not None else self.config.max_tokens
+
+        call_kwargs: dict[str, Any] = {
+            "model": model,
+            "messages": messages,
+            "temperature": temp,
+            "max_tokens": max_tok,
+            **kwargs,
+        }
+        if self._api_base:
+            call_kwargs["api_base"] = self._api_base
+        if self._api_key:
+            call_kwargs["api_key"] = self._api_key
+        if tools:
+            call_kwargs["tools"] = tools
+            call_kwargs["tool_choice"] = "auto"
+
+        logger.debug(f"LLM call: model={model}, base={self._api_base or 'default'}, msgs={len(messages)}, tools={len(tools or [])}")
+
+        try:
+            response = await litellm.acompletion(**call_kwargs)
+        except Exception as e:
+            logger.error(f"LLM call failed: {e}")
+            raise
+
+        usage = getattr(response, "usage", None)
+        cost = 0.0
+        if usage:
+            self._total_tokens_in += getattr(usage, "prompt_tokens", 0)
+            self._total_tokens_out += getattr(usage, "completion_tokens", 0)
+            try:
+                cost = litellm.completion_cost(completion_response=response)
+                self._total_cost += cost
+            except Exception:
+                pass
+
+        choice = response.choices[0]
+        message = choice.message
+
+        result: dict[str, Any] = {
+            "content": message.content or "",
+            "tool_calls": [],
+            "finish_reason": choice.finish_reason,
+            "model": model,
+            "cost": cost,
+            "usage": {
+                "prompt_tokens": getattr(usage, "prompt_tokens", 0) if usage else 0,
+                "completion_tokens": getattr(usage, "completion_tokens", 0) if usage else 0,
+            },
+        }
+
+        if message.tool_calls:
+            for tc in message.tool_calls:
+                args, raw_args, parse_error = _parse_tool_arguments(tc.function.name, tc.function.arguments)
+                tool_call = {
+                    "id": tc.id,
+                    "function": tc.function.name,
+                    "arguments": args,
+                }
+                if raw_args is not None:
+                    tool_call["arguments_raw"] = raw_args
+                if parse_error:
+                    tool_call["arguments_parse_error"] = parse_error
+                result["tool_calls"].append(tool_call)
+
+        return result
+
+    def normalize_stream_event(
+        self,
+        chunk: Any,
+        *,
+        model: str,
+    ) -> list[RuntimeLLMEvent]:
+        events: list[RuntimeLLMEvent] = []
+        usage = getattr(chunk, "usage", None)
+        if usage:
+            events.append(RuntimeLLMEvent(
+                event_type="usage",
+                model=model,
+                payload={
+                    "prompt_tokens": getattr(usage, "prompt_tokens", 0),
+                    "completion_tokens": getattr(usage, "completion_tokens", 0),
+                    "context_window": self.get_context_window(model=model),
+                },
+            ))
+
+        choices = getattr(chunk, "choices", None) or []
+        if not choices:
+            return events
+
+        choice = choices[0]
+        delta = getattr(choice, "delta", None)
+        if delta is not None:
+            text = getattr(delta, "content", None)
+            if text:
+                events.append(RuntimeLLMEvent(
+                    event_type="assistant_delta",
+                    model=model,
+                    payload={"text": text},
+                ))
+            thinking_text = (
+                getattr(delta, "reasoning", None)
+                or getattr(delta, "reasoning_content", None)
+                or getattr(delta, "thinking", None)
+            )
+            if thinking_text:
+                events.append(RuntimeLLMEvent(
+                    event_type="thinking_delta",
+                    model=model,
+                    payload={"text": str(thinking_text)},
+                ))
+            tool_calls = getattr(delta, "tool_calls", None) or []
+            for tool_call in tool_calls:
+                function = getattr(tool_call, "function", None)
+                events.append(RuntimeLLMEvent(
+                    event_type="tool_call_delta",
+                    model=model,
+                    payload={
+                        "index": getattr(tool_call, "index", 0),
+                        "id": getattr(tool_call, "id", ""),
+                        "name": getattr(function, "name", "") if function else "",
+                        "arguments": getattr(function, "arguments", "") if function else "",
+                    },
+                ))
+
+        finish_reason = getattr(choice, "finish_reason", None)
+        if finish_reason:
+            events.append(RuntimeLLMEvent(
+                event_type="message_stop",
+                model=model,
+                payload={"finish_reason": finish_reason},
+            ))
+        return events
+
+    async def chat_stream(
+        self,
+        messages: list[dict[str, Any]],
+        tools: list[dict[str, Any]] | None = None,
+        task_type: str | None = None,
+        temperature: float | None = None,
+        max_tokens: int | None = None,
+        **kwargs: Any,
+    ) -> AsyncIterator[RuntimeLLMEvent]:
+        model = self._select_model(task_type)
+        temp = temperature if temperature is not None else self.config.temperature
+        max_tok = max_tokens if max_tokens is not None else self.config.max_tokens
+
+        call_kwargs: dict[str, Any] = {
+            "model": model,
+            "messages": messages,
+            "temperature": temp,
+            "max_tokens": max_tok,
+            "stream": True,
+            **kwargs,
+        }
+        if self._api_base:
+            call_kwargs["api_base"] = self._api_base
+        if self._api_key:
+            call_kwargs["api_key"] = self._api_key
+        if tools:
+            call_kwargs["tools"] = tools
+            call_kwargs["tool_choice"] = "auto"
+
+        logger.debug(
+            f"LLM stream call: model={model}, base={self._api_base or 'default'}, msgs={len(messages)}, tools={len(tools or [])}"
+        )
+
+        last_usage = {"prompt_tokens": 0, "completion_tokens": 0}
+        yield RuntimeLLMEvent(event_type="message_start", model=model, payload={"model": model})
+
+        try:
+            stream = await litellm.acompletion(**call_kwargs)
+            if hasattr(stream, "__aiter__"):
+                async for chunk in stream:
+                    for event in self.normalize_stream_event(chunk, model=model):
+                        if event.event_type == "usage":
+                            total_prompt = int(event.payload.get("prompt_tokens", 0) or 0)
+                            total_completion = int(event.payload.get("completion_tokens", 0) or 0)
+                            delta_prompt = max(0, total_prompt - last_usage["prompt_tokens"])
+                            delta_completion = max(0, total_completion - last_usage["completion_tokens"])
+                            last_usage["prompt_tokens"] = total_prompt
+                            last_usage["completion_tokens"] = total_completion
+                            cost = 0.0
+                            try:
+                                prompt_cost, completion_cost = litellm.cost_per_token(
+                                    model=model,
+                                    prompt_tokens=delta_prompt,
+                                    completion_tokens=delta_completion,
+                                )
+                                cost = float(prompt_cost or 0.0) + float(completion_cost or 0.0)
+                            except Exception:
+                                cost = 0.0
+                            self._total_tokens_in += delta_prompt
+                            self._total_tokens_out += delta_completion
+                            self._total_cost += cost
+                            event.payload = {
+                                **dict(event.payload),
+                                "prompt_tokens": delta_prompt,
+                                "completion_tokens": delta_completion,
+                                "prompt_tokens_total": total_prompt,
+                                "completion_tokens_total": total_completion,
+                                "estimated_cost_delta": cost,
+                                "estimated_cost_total": self._total_cost,
+                                "context_window": event.payload.get("context_window") or self.get_context_window(model=model),
+                                "model": model,
+                            }
+                        yield event
+            else:
+                # Provider fallback: treat the response as a single non-streaming completion.
+                choice = stream.choices[0]
+                message = choice.message
+                if getattr(message, "content", None):
+                    yield RuntimeLLMEvent(
+                        event_type="assistant_delta",
+                        model=model,
+                        payload={"text": message.content},
+                    )
+                for tc in getattr(message, "tool_calls", None) or []:
+                    yield RuntimeLLMEvent(
+                        event_type="tool_call_delta",
+                        model=model,
+                        payload={
+                            "index": 0,
+                            "id": getattr(tc, "id", ""),
+                            "name": getattr(getattr(tc, "function", None), "name", ""),
+                            "arguments": getattr(getattr(tc, "function", None), "arguments", ""),
+                        },
+                    )
+                usage = getattr(stream, "usage", None)
+                if usage:
+                    cost = 0.0
+                    prompt_tokens = int(getattr(usage, "prompt_tokens", 0) or 0)
+                    completion_tokens = int(getattr(usage, "completion_tokens", 0) or 0)
+                    try:
+                        prompt_cost, completion_cost = litellm.cost_per_token(
+                            model=model,
+                            prompt_tokens=prompt_tokens,
+                            completion_tokens=completion_tokens,
+                        )
+                        cost = float(prompt_cost or 0.0) + float(completion_cost or 0.0)
+                    except Exception:
+                        cost = 0.0
+                    self._total_tokens_in += prompt_tokens
+                    self._total_tokens_out += completion_tokens
+                    self._total_cost += cost
+                    yield RuntimeLLMEvent(
+                        event_type="usage",
+                        model=model,
+                        payload={
+                            "prompt_tokens": prompt_tokens,
+                            "completion_tokens": completion_tokens,
+                            "prompt_tokens_total": prompt_tokens,
+                            "completion_tokens_total": completion_tokens,
+                            "estimated_cost_delta": cost,
+                            "estimated_cost_total": self._total_cost,
+                            "context_window": self.get_context_window(model=model),
+                            "model": model,
+                        },
+                    )
+                yield RuntimeLLMEvent(
+                    event_type="message_stop",
+                    model=model,
+                    payload={"finish_reason": getattr(choice, "finish_reason", "stop")},
+                )
+        except Exception as e:
+            logger.error(f"LLM stream failed: {e}")
+            yield RuntimeLLMEvent(
+                event_type="error",
+                model=model,
+                payload={"message": str(e)},
+            )
+            raise
+
+    async def simple_chat(
+        self,
+        prompt: str,
+        system: str | None = None,
+        task_type: str | None = None,
+    ) -> str:
+        messages: list[dict[str, Any]] = []
+        if system:
+            messages.append({"role": "system", "content": system})
+        messages.append({"role": "user", "content": prompt})
+        result = await self.chat(messages, task_type=task_type)
+        return result["content"]
+
+    def get_tool_definitions(self, tools: list[dict[str, Any]]) -> list[dict[str, Any]]:
+        """Convert internal tool definitions to OpenAI function-calling format."""
+        formatted = []
+        for tool in tools:
+            formatted.append({
+                "type": "function",
+                "function": {
+                    "name": tool["name"],
+                    "description": tool.get("description", ""),
+                    "parameters": tool.get("parameters", {"type": "object", "properties": {}}),
+                },
+            })
+        return formatted
+
+    def _build_direct_attachment_parts(
+        self,
+        model: str,
+        attachment_refs: list[dict[str, Any]],
+    ) -> list[dict[str, Any]]:
+        capabilities = self._attachment_capabilities(model)
+        if not capabilities["enabled"]:
+            return []
+
+        parts: list[dict[str, Any]] = []
+        for ref_dict in attachment_refs:
+            try:
+                ref = AttachmentRef.from_dict(ref_dict)
+                data_url = self._attachment_data_url(ref)
+            except Exception as exc:
+                logger.warning(f"Skipping direct attachment payload: {exc}")
+                continue
+
+            if not data_url:
+                continue
+
+            if ref.mime_type.startswith("image/") and capabilities["image_mode"]:
+                parts.append(self._build_attachment_part("image_url", ref, data_url))
+            elif ref.mime_type == "application/pdf" and capabilities["pdf_mode"]:
+                parts.append(self._build_attachment_part(str(capabilities["pdf_mode"]), ref, data_url))
+            elif ref.mime_type.startswith("video/") and capabilities["video_mode"]:
+                parts.append(self._build_attachment_part(str(capabilities["video_mode"]), ref, data_url))
+
+        return parts
+
+    def _build_attachment_part(
+        self,
+        mode: str,
+        ref: AttachmentRef,
+        data_url: str,
+    ) -> dict[str, Any]:
+        if mode == "image_url":
+            return {
+                "type": "image_url",
+                "image_url": {"url": data_url},
+            }
+        if mode == "video_url":
+            return {
+                "type": "video_url",
+                "video_url": {"url": data_url},
+            }
+        if mode == "file":
+            return {
+                "type": "file",
+                "file": {
+                    "file_data": data_url,
+                    "filename": ref.filename,
+                },
+            }
+        raise ValueError(f"Unsupported attachment transport mode: {mode}")
+
+    def _attachment_capabilities(self, model: str) -> dict[str, Any]:
+        provider = model.split("/", 1)[0].strip().lower()
+        api_base = (self._api_base or "").lower()
+
+        image_mode: str | None = None
+        pdf_mode: str | None = None
+        video_mode: str | None = None
+
+        if "api.poe.com" in api_base:
+            image_mode = "image_url"
+            pdf_mode = "file"
+            if _looks_like_multimodal_model(model):
+                video_mode = "file"
+        elif "openrouter.ai" in api_base:
+            image_mode = "image_url"
+            pdf_mode = "file"
+            if _looks_like_video_capable_model(model):
+                video_mode = "video_url"
+        elif provider in {"openai", "azure", "anthropic"}:
+            image_mode = "image_url"
+            pdf_mode = "file"
+        elif provider in {"google", "gemini", "vertex_ai", "vertex"}:
+            image_mode = "image_url"
+            pdf_mode = "file"
+            if _looks_like_video_capable_model(model):
+                video_mode = "video_url"
+        elif _looks_like_multimodal_model(model):
+            image_mode = "image_url"
+            pdf_mode = "file" if _looks_like_document_capable_model(model) else None
+            if _looks_like_video_capable_model(model):
+                video_mode = "video_url"
+
+        return {
+            "enabled": bool(image_mode or pdf_mode or video_mode),
+            "image_mode": image_mode,
+            "pdf_mode": pdf_mode,
+            "video_mode": video_mode,
+        }
+
+    def _attachment_data_url(self, ref: AttachmentRef) -> str | None:
+        path = self._resolve_attachment_path(ref)
+        if path is None:
+            return None
+        payload = base64.b64encode(path.read_bytes()).decode("ascii")
+        mime_type = ref.mime_type or _guess_mime_from_filename(ref.filename)
+        return f"data:{mime_type};base64,{payload}"
+
+    def _resolve_attachment_path(self, ref: AttachmentRef) -> Path | None:
+        if not self.opc_home or not ref.disk_path:
+            return None
+        resolved = (self.opc_home / ref.disk_path).resolve()
+        opc_home_resolved = self.opc_home.resolve()
+        if not str(resolved).startswith(str(opc_home_resolved)):
+            raise ValueError(f"Attachment path escapes OPC home: {ref.disk_path}")
+        return resolved
+
+
+def _guess_mime_from_filename(filename: str) -> str:
+    suffix = attachment_suffix(filename)
+    if suffix == ".pdf":
+        return "application/pdf"
+    if suffix == ".docx":
+        return "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
+    if suffix == ".xlsx":
+        return "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
+    if suffix == ".pptx":
+        return "application/vnd.openxmlformats-officedocument.presentationml.presentation"
+    if suffix == ".mp4":
+        return "video/mp4"
+    if suffix in {".mpeg", ".mpg"}:
+        return "video/mpeg"
+    if suffix == ".mov":
+        return "video/quicktime"
+    if suffix == ".webm":
+        return "video/webm"
+    return "application/octet-stream"