feat(agent): Gradio-powered LangGraph agent chat with streaming, tool calls, file upload, conversation persistence

- Gradio 5.50.0 ChatInterface with type='messages' streaming
- LangGraph create_react_agent with InMemorySaver checkpointer
- 4 @tool functions: search_dashboards, get_health_summary, list_environments, get_task_status
- Structured ChatMessage metadata (7 discriminator types: stream_token, tool_start/end/error, confirm_required, confirm_resolved, error)
- HITL resume via second submit() with interrupt_before/Command
- Dual-identity RBAC: service JWT + user JWT for tool calls
- File upload (10 MB limit, pdfplumber/xlsx/JSON parser)
- Conversation persistence via POST /api/agent/conversations/save
- REST API: list, history, archive conversations; multi-tab gate; LLM config
- LLM provider selection via Admin -> LLM Settings (assistant_planner_provider)
- Svelte 5 AgentChatModel with stream event queue, dedup, stream_status watcher
- MarkdownRenderer using svelte-markdown with semantic Tailwind tokens
- ToolCallCard (3 states: executing/completed/failed)
- ConversationList with search, date grouping, infinite scroll
- ConnectionIndicator with Gradio health status
- /agent route with two-column layout
- Vite proxy /api/agent/gradio -> Gradio SSE
- Fixed: not_() SQLAlchemy operator, route collision with _admin_routes
- Fixed: conversation_id -> id normalization, .pyc cache staleness
- Fixed: event.data array parsing (Gradio returns [jsonStr, null])
- Requirements pinned: gradio==5.50.0, pydantic>=2.7,<=2.12.3

backend/src/agent/document_parser.py

@@ -0,0 +1,87 @@
+# backend/src/agent/document_parser.py
+# #region AgentChat.Document.Parser [C:3] [TYPE Module] [SEMANTICS agent-chat,document,parser]
+# @defgroup AgentChat Parse PDF and XLSX files into text/structured data.
+# @RELATION DEPENDS_ON -> [EXT:pdfplumber]
+# @RELATION DEPENDS_ON -> [EXT:openpyxl]
+# @PRE File exists, valid format, ≤10MB.
+# @POST Returns extracted text (PDF) or structured dict (XLSX).
+
+from pathlib import Path
+
+
+class ParseError(Exception):
+    """Raised when document parsing fails."""
+
+
+def parse_pdf(file_path: str) -> str:
+    """Extract text from PDF using pdfplumber (primary) with PyPDF2 fallback."""
+    try:
+        import pdfplumber
+    except ImportError:
+        raise ParseError("pdfplumber not installed") from None
+
+    try:
+        with pdfplumber.open(file_path) as pdf:
+            pages = []
+            for page in pdf.pages:
+                text = page.extract_text()
+                if text:
+                    pages.append(text)
+            return "\n\n".join(pages) if pages else ""
+    except Exception as e:
+        # Fallback to PyPDF2
+        try:
+            import PyPDF2
+            with open(file_path, "rb") as f:
+                reader = PyPDF2.PdfReader(f)
+                return "\n\n".join(p.extract_text() for p in reader.pages if p.extract_text())
+        except Exception:
+            raise ParseError(f"Failed to parse PDF: {e}") from None
+
+
+def parse_xlsx(file_path: str) -> str:
+    """Extract structured data from XLSX — sheet names + cell data."""
+    try:
+        import openpyxl
+    except ImportError:
+        raise ParseError("openpyxl not installed") from None
+
+    try:
+        wb = openpyxl.load_workbook(file_path, read_only=True, data_only=True)
+        parts = []
+        for sheet_name in wb.sheetnames:
+            ws = wb[sheet_name]
+            rows = []
+            for row in ws.iter_rows(values_only=True):
+                cells = [str(c) if c is not None else "" for c in row]
+                rows.append("\t".join(cells))
+            parts.append(f"=== Sheet: {sheet_name} ===\n" + "\n".join(rows))
+        return "\n\n".join(parts)
+    except Exception as e:
+        raise ParseError(f"Failed to parse XLSX: {e}") from e
+
+
+def parse_upload(file_data) -> str:
+    """Parse an uploaded file based on its extension.
+
+    Args:
+        file_data: str (file path) or dict with "name" and "path"/"file_path" keys.
+    """
+    if isinstance(file_data, str):
+        path = file_data
+        name = Path(path).name
+    else:
+        name = file_data.get("name", "")
+        path = file_data.get("path", file_data.get("file_path", ""))
+    ext = Path(name).suffix.lower()
+
+    if ext == ".pdf":
+        return parse_pdf(path)
+    elif ext in (".xlsx", ".xls"):
+        return parse_xlsx(path)
+    elif ext in (".json", ".csv", ".txt"):
+        with open(path, encoding="utf-8", errors="replace") as f:
+            return f.read(100_000)  # truncate at ~100k chars
+    else:
+        raise ParseError(f"Unsupported format: {ext}. Supported: PDF, XLSX, JSON, CSV, TXT")
+# #endregion AgentChat.Document.Parser