pencil-agent-skill

name	pencil-agent-skill
description	Use the Pencil Workbench to create and edit vector graphics, including illustrations, diagrams, and UI components, with human review.

Use this skill when you are working with the Pencil Agentic App, the Pencil Workbench, or tools named pencil_*.

System Of Record

• Pencil middleware tools are the persistence path. Do not claim a design is saved, imported, exported, reviewed, archived, or versioned until the matching tool succeeds.
• Prefer the current Workbench document from env.pencilDocumentId or pencilContextJson.
• Mutating Pencil core tools update the working copy. They do not create a version. Use pencil_save_version for durable review checkpoints.
• Use pencil_create_sample_document when the user wants a realistic starting case or asks to verify the app with real dashboard data.

Workbench Context

Workbench state variables may include:

• pencilDocumentId: selected document.
• pencilVersionId: selected version.
• pencilNodeId: selected node.
• pencilSelectionJson: compact selection context.
• pencilContextJson: compact document, version, and graph context.
• pencilDirty: local dirty state.

When context is present, parse it before choosing tools. Only create a new document when no current document exists or the user explicitly asks for a new one.

File Import And Export

• Import .fig and .pen with pencil_import_file.
• Pass /workspace/..., workspace-relative paths, or portable file references directly.
• Export with pencil_export_file. Return the workspace path/reference, MIME type, size, and sha256.
• Do not return large base64 payloads to the user.

Node Editing

• Before creating a new design, call pencil_list_typography_presets, choose one preset for the content and language, and use only its returned managed font family names. Do not invent font URLs.
• Call pencil_get_document before modifying existing user-edited documents.
• Call pencil_get_node before targeted edits to a selected node.
• Use selected pencil_* core tools for layout, style, structure, variables, analysis, and node reads/writes.
• For complex pages, render a small empty root frame first, then add one major region per pencil_render call with parent_id and insert_index. Keep the returned node ids for targeted follow-up work.
• Use replace_id to replace one placeholder or incorrect region. Do not regenerate an already successful page merely because another region failed.
• When using pencil_render, write OpenPencil JSX with flex="col" or flex="row" for auto-layout direction. Use gap, p/px/py/pt/pr/pb/pl, w/h, bg, rounded, stroke, and strokeWidth props. Do not use flow for auto-layout direction; flow is reserved for reading direction.
• If pencil_render returns success=false, recoverable=true, and a renderDraftId, call pencil_render_patch. Pass the returned revision and replace only the smallest uniquely matching oldText fragment. Never resend the complete JSX while an active draft is available.
• A failed render draft does not modify the document. A successful patch commits exactly one new working-copy revision.
• For complex auto-layout changes, prefer pencil_set_layout and pencil_set_layout_child, then read the document summary before saving a version.
• Always pass documentId.
• Keep changeSummary short and operational.

Failure Recovery

If an import, export, graph edit, or save fails:

1. For a recoverable render diagnostic, repair its retained source with pencil_render_patch before reporting a terminal failure.
2. Record unrecoverable failures with pencil_report_failure.
3. Tell the user what failed and whether it is recoverable.
4. Suggest a concrete next step, such as reloading the document, saving the current working copy, or retrying with a smaller target selection.