Data Skill

Data Access Skill

Work with raw local data through the data tool. Check the tool in your tool list for the full schema; this skill covers strategy, not parameters.

The two path namespaces

• reports/q3.csv — workspace-relative (the workflow's own scratch space, always readable and writable)
• mnt/<mount_name>/file.csv — an external folder the operator approved; read-only unless its writable flag is on

You MUST start with list on an empty path: it returns the workspace root AND the mounts enabled on this node (with their writable flags). Never guess mount names.

Reading — pick the honest tier, page deliberately

read auto-detects text / csv / json / pdf / html / xlsx / image / binary from the extension; as_type forces a tier when the extension lies.

• Everything is paged with offset / limit. Check truncated and rows_total / lines_total / pages_total before summarizing — a truncated read is a sample, not the file.
• Skim first, then zoom: read with the default limit to see the shape, then page into the region that matters. Do not crank limit to the max on the first read of an unknown file.
• CSV/XLSX return columns + rows; JSON deep structures are pruned at depth 8 (pruned_paths tells you where — read a subpath as text if you need what was pruned).
• Images return metadata plus a file reference — if the host model supports vision the image itself becomes visible; otherwise use the vision tool.
• Binary files return a reference and checksum, never content. Pass the reference's path to a tool that can handle the format.

Writing — bounded and non-destructive

• write replaces, append extends; both are UTF-8 text, workspace or writable mounts only.
• There is NO delete. Do not try to empty files as a substitute; tell the user deletion is a manual action in the gallery panel.
• copy_to_workspace imports a mount file into the workspace (never overwrites — it suffixes). Use it before operations that need a workspace reference: previews, drags, vision on mount images.

Anti-patterns

• Guessing paths instead of list/search first.
• Re-reading a whole file when you already have the page you need — results persist in your context; reread only new offsets.
• Reading a huge JSON as json when you need one field — read as text and page, or search first.
• Asking for a mount that is not in your list result: mounts are operator-controlled; you cannot add them.