docs: Data Designer Got Skills dev note

[johnnygreco]

Summary

• First draft of the "Data Designer Got Skills" dev note covering the new agent-first CLI and Claude Code skill for Data Designer
• Includes hero benchmark figure, baseline and skill trace embeds, mascot image, and full prose across all sections
• Benchmarked across 228 sessions each for skill and baseline: ~80% fewer tokens, ~90% fewer errors, ~47% faster, improved quality (4.0 → 4.7)

[greptile-apps]

Greptile Summary

This PR introduces the "Data Designer Got Skills" dev note, documenting the new agent-first CLI and Claude Code skill for Data Designer. It covers motivation, design decisions, benchmark results (228 sessions each for skill vs. baseline), and getting-started instructions. Alongside the prose, it ships the plugin.json and marketplace registration needed to publish the skill, and reorganises existing dev-note assets from a flat images/ directory into per-post assets/<post-name>/ subdirectories.

Key changes:

• New dev note data-designer-got-skills.md with benchmark figures and embedded session traces
• New skills/data-designer/.claude-plugin/plugin.json and top-level .claude-plugin/marketplace.json to register the skill in the Claude Code marketplace
• Asset path refactoring for three existing posts (design-principles, search-agent, structured-outputs-from-nemotron) to match the new directory layout
• Minor grammatical issue: "1 errors" in trace-baseline.html should be "1 error"

Confidence Score: 5/5

• This PR is safe to merge; it is a documentation and metadata-only change with one trivial grammatical fix remaining.
• All changes are documentation, static assets, and plugin metadata — no runtime code is affected. The asset path refactoring is straightforward and consistent across all three updated posts. The only issue found is a cosmetic grammar mistake ("1 errors") in an HTML trace embed, which has no functional impact.
• No files require special attention beyond the one-line grammar fix in trace-baseline.html.

Important Files Changed

Filename	Overview
docs/devnotes/posts/data-designer-got-skills.md	New dev note covering the agent-first CLI and Claude Code skill; prose, benchmark data, and embed snippets look correct and consistent with each other.
docs/devnotes/posts/assets/data-designer-got-skills/trace-baseline.html	Baseline session trace HTML; contains a minor grammatical error ("1 errors" → "1 error") on line 9, otherwise structurally sound.
docs/devnotes/posts/assets/data-designer-got-skills/trace-skill.html	Skill session trace HTML containing the shared CSS block; the style coupling concern (raised in a previous thread) is the only known issue.
skills/data-designer/.claude-plugin/plugin.json	New plugin metadata file; all required fields present and consistent with marketplace.json and SKILL.md.
.claude-plugin/marketplace.json	New marketplace registration file; plugin name, source path, and keywords are all consistent with the skill directory structure.
mkdocs.yml	Adds the new dev note entry at the top of the nav list (most-recent-first ordering), consistent with existing pattern.

Sequence Diagram

sequenceDiagram
    participant User
    participant ClaudeCode as Claude Code
    participant Skill as data-designer Skill
    participant CLI as data-designer CLI

    User->>ClaudeCode: /data-designer [dataset description]
    ClaudeCode->>Skill: Load SKILL.md + select workflow mode
    Skill->>CLI: data-designer agent context
    CLI-->>Skill: Curated code-derived context (column types, samplers, models)
    Skill->>ClaudeCode: Write config script
    ClaudeCode->>CLI: data-designer validate <file>
    CLI-->>ClaudeCode: Validation result
    alt Validation fails
        ClaudeCode->>ClaudeCode: Self-correct config
        ClaudeCode->>CLI: data-designer validate <file>
        CLI-->>ClaudeCode: Validation result
    end
    ClaudeCode->>CLI: data-designer preview <file>
    CLI-->>ClaudeCode: Sample records
    ClaudeCode->>CLI: data-designer create <file> --num-records N
    CLI-->>User: Generated dataset

Loading

Prompt To Fix All With AI

This is a comment left during a code review.
Path: docs/devnotes/posts/assets/data-designer-got-skills/trace-baseline.html
Line: 9

Comment:
**Grammatical error in error count label**

`"1 errors"` is grammatically incorrect for a singular count. It should read `"1 error"`.

```suggestion
<span class="st-stat err">1 error</span>
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (10): Last reviewed commit: "slope-guard tweaks" | Re-trigger Greptile}

[nabinchha]

🚀