feat: inline data file viewer for tabular data

[dimavedenyapin]

Summary

• Inline data file previews in agent chat: when a tool call reads/writes a CSV, JSON, Excel, or TSV file, an interactive table automatically renders below the tool call
• Fullscreen dialog with search/filter, column sorting, and expanded row limits (5000 rows)
• Smart attachment handling: tabular file attachments open in the built-in viewer instead of the OS default app
• File parsing in main process via papaparse (CSV/TSV) and xlsx (Excel), keeping the renderer thread fast

Architecture

Layer	Change
Main process	New fileViewer:readTabularFile and fileViewer:getFileInfo IPC handlers + attachments:resolvePath
Preload	Exposed fileViewer and attachments.resolvePath namespaces
Renderer	New DataFilePreview (inline) and DataFileDialog (fullscreen) components
AgentTranscriptPanel	Auto-detects tabular files in ToolCallMessage tool inputs
TaskAttachments	Routes tabular file clicks to DataFileDialog

Supported Formats

CSV, TSV, JSON, JSONL, XLSX, XLS (Parquet placeholder for future)

Screenshot generated with Remotion

The PR screenshot above was rendered programmatically using Remotion (scripts/remotion/).

Test plan

• Attach a CSV file to a task → click it → DataFileDialog opens with sortable table
• Run agent that reads a .csv file → inline DataFilePreview appears in chat transcript
• Click "View full table" or expand icon → fullscreen dialog opens
• Sort columns by clicking headers, verify sort order toggles
• Attach a .json array file → verify it opens in data viewer
• Attach a .xlsx file → verify Excel parsing works
• Verify non-tabular files (.pdf, .png) still open with OS default app

🤖 Generated with Claude Code