Conciseness

The body is lean and assumes competence — it teaches non-obvious internal architecture without padding — but the embed vs fetchData distinction is explained twice (in 'The pattern' and again in 'Two data strategies') and the closing checklist recaps points already made, so minor trimming is possible.

Actionability

It provides a concrete numbered TSX template (useState instance creation, event subscription with disposal, render via <PositronDataGrid instance={...} />), named example subclasses, and specific decision guidance ('is the dataset bounded and small? Embed'). Placeholders like MySubclass and onDidSomething keep it just short of copy-paste-ready, fitting the mostly-executable anchor.

Workflow Clarity

The sequence is explicitly numbered (pick subclass, create once, subscribe, dispose, render), includes decision checkpoints ('Is there an existing subclass that fits?'), an error-detection feedback loop (anti-pattern symptoms with 'If you see those, delete the wrapper'), and a final checklist — matching the clear-sequence-with-validation anchor. No destructive or batch operations, so no cap applies.

Progressive Disclosure

A single-file skill (no references/, scripts/, or assets/ directories exist) with well-organized, clearly headed sections. However, at ~127 lines it exceeds the under-50-line single-file exception, and content such as the existing-subclasses reference list and strategy detail could plausibly live in a separate reference file, so structure is good rather than exemplary.

Specificity

The description names a concrete domain ('building a list, table, grid, or virtualized scrolling UI in Positron') and one concrete capability ('Avoids the common mistake of mediating props into the instance via useEffect'), but does not list several specific actions, so it matches the '1-2 concrete actions, not comprehensive' anchor rather than the several-actions anchor.

Completeness

It has an explicit 'when' ('Use when building a list, table, grid, or virtualized scrolling UI in Positron, or touching...') and a stated 'what' ('Avoids the common mistake of mediating props into the instance via useEffect'), but the 'what' is thin and does not enumerate capabilities, so it sits at the both-present-but-not-fully-explicit anchor.

Trigger Term Quality

Natural trigger phrases are strong ('list, table, grid, virtualized scrolling UI') and supplemented by class-name triggers ('DataGridInstance / PositronDataGrid'), but a few natural variations users might say (e.g. 'data explorer', 'virtual list', 'spreadsheet view') are absent, matching the good-but-incomplete keyword coverage anchor.

Distinctiveness Conflict Risk

The description is scoped to Positron and names unique class identifiers ('DataGridInstance / PositronDataGrid'), giving it a clear niche with distinct triggers and minimal risk of firing for unrelated skills.