feat: add context file support

api/core/file/file_manager.py

@@ -1,4 +1,5 @@
 import base64
+import logging
 from collections.abc import Mapping
 
 from configs import dify_config
@@ -10,7 +11,10 @@ from core.model_runtime.entities import (
     TextPromptMessageContent,
     VideoPromptMessageContent,
 )
-from core.model_runtime.entities.message_entities import PromptMessageContentUnionTypes
+from core.model_runtime.entities.message_entities import (
+    MultiModalPromptMessageContent,
+    PromptMessageContentUnionTypes,
+)
 from core.tools.signature import sign_tool_file
 from extensions.ext_storage import storage
 
@@ -18,6 +22,8 @@ from . import helpers
 from .enums import FileAttribute
 from .models import File, FileTransferMethod, FileType
 
+logger = logging.getLogger(__name__)
+
 
 def get_attr(*, file: File, attr: FileAttribute):
     match attr:
@@ -89,6 +95,8 @@ def to_prompt_message_content(
         "format": f.extension.removeprefix("."),
         "mime_type": f.mime_type,
         "filename": f.filename or "",
+        # Encoded file reference for context restoration: "transfer_method:related_id" or "remote:url"
+        "file_ref": _encode_file_ref(f),
     }
     if f.type == FileType.IMAGE:
         params["detail"] = image_detail_config or ImagePromptMessageContent.DETAIL.LOW
@@ -96,6 +104,17 @@ def to_prompt_message_content(
     return prompt_class_map[f.type].model_validate(params)
 
 
+def _encode_file_ref(f: File) -> str | None:
+    """Encode file reference as 'transfer_method:id_or_url' string."""
+    if f.transfer_method == FileTransferMethod.REMOTE_URL:
+        return f"remote:{f.remote_url}" if f.remote_url else None
+    elif f.transfer_method == FileTransferMethod.LOCAL_FILE:
+        return f"local:{f.related_id}" if f.related_id else None
+    elif f.transfer_method == FileTransferMethod.TOOL_FILE:
+        return f"tool:{f.related_id}" if f.related_id else None
+    return None
+
+
 def download(f: File, /):
     if f.transfer_method in (
         FileTransferMethod.TOOL_FILE,
@@ -164,3 +183,128 @@ def _to_url(f: File, /):
         return sign_tool_file(tool_file_id=f.related_id, extension=f.extension)
     else:
         raise ValueError(f"Unsupported transfer method: {f.transfer_method}")
+
+
+def restore_multimodal_content(
+    content: MultiModalPromptMessageContent,
+) -> MultiModalPromptMessageContent:
+    """
+    Restore base64_data or url for multimodal content from file_ref.
+
+    file_ref format: "transfer_method:id_or_url" (e.g., "local:abc123", "remote:https://...")
+
+    Args:
+        content: MultiModalPromptMessageContent with file_ref field
+
+    Returns:
+        MultiModalPromptMessageContent with restored base64_data or url
+    """
+    # Skip if no file reference or content already has data
+    if not content.file_ref:
+        return content
+    if content.base64_data or content.url:
+        return content
+
+    try:
+        file = _build_file_from_ref(
+            file_ref=content.file_ref,
+            file_format=content.format,
+            mime_type=content.mime_type,
+            filename=content.filename,
+        )
+        if not file:
+            return content
+
+        # Restore content based on config
+        if dify_config.MULTIMODAL_SEND_FORMAT == "base64":
+            restored_base64 = _get_encoded_string(file)
+            return content.model_copy(update={"base64_data": restored_base64})
+        else:
+            restored_url = _to_url(file)
+            return content.model_copy(update={"url": restored_url})
+
+    except Exception as e:
+        logger.warning("Failed to restore multimodal content: %s", e)
+        return content
+
+
+def _build_file_from_ref(
+    file_ref: str,
+    file_format: str | None,
+    mime_type: str | None,
+    filename: str | None,
+) -> File | None:
+    """
+    Build a File object from encoded file_ref string.
+
+    Args:
+        file_ref: Encoded reference "transfer_method:id_or_url"
+        file_format: The file format/extension (without dot)
+        mime_type: The mime type
+        filename: The filename
+
+    Returns:
+        File object with storage_key loaded, or None if not found
+    """
+    from sqlalchemy import select
+    from sqlalchemy.orm import Session
+
+    from extensions.ext_database import db
+    from models.model import UploadFile
+    from models.tools import ToolFile
+
+    # Parse file_ref: "method:value"
+    if ":" not in file_ref:
+        logger.warning("Invalid file_ref format: %s", file_ref)
+        return None
+
+    method, value = file_ref.split(":", 1)
+    extension = f".{file_format}" if file_format else None
+
+    if method == "remote":
+        return File(
+            tenant_id="",
+            type=FileType.IMAGE,
+            transfer_method=FileTransferMethod.REMOTE_URL,
+            remote_url=value,
+            extension=extension,
+            mime_type=mime_type,
+            filename=filename,
+            storage_key="",
+        )
+
+    # Query database for storage_key
+    with Session(db.engine) as session:
+        if method == "local":
+            stmt = select(UploadFile).where(UploadFile.id == value)
+            upload_file = session.scalar(stmt)
+            if upload_file:
+                return File(
+                    tenant_id=upload_file.tenant_id,
+                    type=FileType(upload_file.extension)
+                    if hasattr(FileType, upload_file.extension.upper())
+                    else FileType.IMAGE,
+                    transfer_method=FileTransferMethod.LOCAL_FILE,
+                    related_id=value,
+                    extension=extension or ("." + upload_file.extension if upload_file.extension else None),
+                    mime_type=mime_type or upload_file.mime_type,
+                    filename=filename or upload_file.name,
+                    storage_key=upload_file.key,
+                )
+        elif method == "tool":
+            stmt = select(ToolFile).where(ToolFile.id == value)
+            tool_file = session.scalar(stmt)
+            if tool_file:
+                return File(
+                    tenant_id=tool_file.tenant_id,
+                    type=FileType.IMAGE,
+                    transfer_method=FileTransferMethod.TOOL_FILE,
+                    related_id=value,
+                    extension=extension,
+                    mime_type=mime_type or tool_file.mimetype,
+                    filename=filename or tool_file.name,
+                    storage_key=tool_file.file_key,
+                )
+
+    logger.warning("File not found for file_ref: %s", file_ref)
+    return None