Cover Image Generator skill

Cover Image Generator

Generate elegant cover images for articles with 5-dimensional customization.

User Input Tools

When this skill prompts the user, follow this tool-selection rule (priority order):

1. Prefer built-in user-input tools exposed by the current agent runtime — e.g., AskUserQuestion, request_user_input, clarify, ask_user, or any equivalent.
2. Fallback: if no such tool exists, emit a numbered plain-text message and ask the user to reply with the chosen number/answer for each question.
3. Batching: if the tool supports multiple questions per call, combine all applicable questions into a single call; if only single-question, ask them one at a time in priority order.

Concrete AskUserQuestion references below are examples — substitute the local equivalent in other runtimes.

Image Generation Tools

When this skill needs to render an image, resolve the backend in this order:

1. Current-request override — if the user names a specific backend in the current message, use it.
2. Saved preference — if EXTEND.md sets preferred_image_backend to a backend available right now, use it.
3. Auto-select (when the preference is auto, unset, or the pinned backend isn't available):
   • Codex (imagegen) — first, inspect your available-skills / tool inventory. If a skill named imagegen is listed, you are running inside Codex and MUST use it: invoke via the Skill tool with skill: "imagegen", passing the saved prompt file's content (plus output path and aspect ratio per Codex imagegen's own args). Codex imagegen is the official raster backend in that runtime and outranks any non-native skill (e.g., baoyu-image-gen) unless the user has explicitly pinned a different preferred_image_backend.
   • Codex via codex exec (codex-imagegen) — if the current runtime exposes no native imagegen skill but the codex CLI is on PATH with an active codex login, route through baoyu-image-gen --provider codex-cli (preferred), or — if baoyu-image-gen is unavailable — invoke the bundled wrapper directly. Details, parameters, and the runtime-discovery procedure live in references/codex-imagegen.md — load that file only when this branch is selected.
   • Cursor (GenerateImage) — if the runtime exposes a native GenerateImage tool, you are running inside Cursor and it outranks any non-native skill the same way Codex imagegen does. Two hard caveats: (a) it has no aspect-ratio parameter — state the target aspect ratio / dimensions explicitly in the prompt text passed as description; (b) it does not accept an output directory — it saves to a tool-managed location, so after generation copy/move the file to the skill's expected output path (e.g., outputs/.../NN-xxx.png). Reference images go in reference_image_paths.
   • Other runtime-native tools — if the runtime exposes a different native image tool (e.g., Hermes image_generate), use it the same way.
   • Otherwise, if exactly one non-native backend is installed (e.g., baoyu-image-gen), use it.
   • Otherwise (multiple non-native backends with no runtime-native tool), ask the user once — batch with any other initial questions.
4. If none are available, tell the user and ask how to proceed.

⛔ Never substitute SVG, HTML, canvas, or other code-based rendering for raster image generation. Codex imagegen's own description says it should be used "when the output should be a bitmap asset rather than repo-native code or vector." If you cannot resolve a raster backend via step 3, fall through to step 4 and ask the user — do not silently emit SVG, write inline <svg> markup, or produce HTML/CSS art as a substitute. This applies even if the article/section seems "diagram-like": the consumer skill calling this rule has already decided that a raster image is what it needs.

⛔ Never repair rendered text by painting over a generated bitmap. Do not use ImageMagick, Pillow, Canvas, SVG, HTML/CSS, OCR scripts, or any other programmatic overlay to cover, rewrite, erase, stroke, or replace title/subtitle text inside an already generated cover image. If text is wrong or unclear, regenerate from a corrected prompt, switch to a lower-text or no-title variant, or ask the user which imperfect candidate to keep.

Setting preferred_image_backend: ask forces the step-3 prompt every run regardless of available backends. Users change the pinned backend via the ## Changing Preferences section below.

Prompt file requirement (hard): write each image's full, final prompt to a standalone file under prompts/ (naming: NN-{type}-[slug].md) BEFORE invoking any backend. The backend receives the prompt file (or its content); the file is the reproducibility record and lets you switch backends without regenerating prompts.

Concrete tool names (imagegen, GenerateImage, image_generate, baoyu-image-gen) above are examples — substitute the local equivalents under the same rule.

Confirmation Policy

Default behavior: confirm before generation.

• Treat explicit skill invocation, a file path, matched keywords/presets, EXTEND.md defaults, and any documented auto-selection as recommendation inputs only. None of them authorizes skipping confirmation.
• Do not start Step 3 or Step 4 until the user confirms the dimensions / aspect / language / backend choices.
• Skip confirmation only when the current request explicitly says to do so, for example: --quick, "直接生成", "不用确认", "跳过确认", "按默认出图", or equivalent wording. quick_mode: true in EXTEND.md counts as a standing explicit opt-out — set it only when you want every run to skip Step 2.
• If confirmation is skipped explicitly, state the assumed dimensions / aspect / language / backend in the next user-facing update before generating.

Options

Option	Description
--type <name>	hero, conceptual, typography, metaphor, scene, minimal
--palette <name>	warm, elegant, cool, dark, earth, vivid, pastel, mono, retro, duotone, macaron
--rendering <name>	flat-vector, hand-drawn, painterly, digital, pixel, chalk, screen-print
--style <name>	Preset shorthand (see Style Presets)
--text <level>	none, title-only, title-subtitle, text-rich
--mood <level>	subtle, balanced, bold
--font <name>	clean, handwritten, serif, display
--aspect <ratio>	16:9 (default), 2.35:1, 4:3, 3:2, 1:1, 3:4
--lang <code>	Title language (en, zh, ja, etc.)
--no-title	Alias for --text none
--quick	Skip confirmation, use auto-selection
--ref <files...>	Reference images for style/composition guidance

Five Dimensions

Dimension	Values	Default
Type	hero, conceptual, typography, metaphor, scene, minimal	auto
Palette	warm, elegant, cool, dark, earth, vivid, pastel, mono, retro, duotone, macaron	auto
Rendering	flat-vector, hand-drawn, painterly, digital, pixel, chalk, screen-print	auto
Text	none, title-only, title-subtitle, text-rich	title-only
Mood	subtle, balanced, bold	balanced
Font	clean, handwritten, serif, display	clean

Auto-selection rules: references/auto-selection.md

Galleries

Types: hero, conceptual, typography, metaphor, scene, minimal → Details: references/types.md

Palettes: warm, elegant, cool, dark, earth, vivid, pastel, mono, retro, duotone, macaron → Details: references/palettes/

Renderings: flat-vector, hand-drawn, painterly, digital, pixel, chalk, screen-print → Details: references/renderings/

Text Levels: none (pure visual) | title-only (default) | title-subtitle | text-rich (with tags) → Details: references/dimensions/text.md

Mood Levels: subtle (low contrast) | balanced (default) | bold (high contrast) → Details: references/dimensions/mood.md

Fonts: clean (sans-serif) | handwritten | serif | display (bold decorative) → Details: references/dimensions/font.md

File Structure

Output directory per default_output_dir preference:

• same-dir: {article-dir}/
• imgs-subdir: {article-dir}/imgs/
• independent (default): cover-image/{topic-slug}/

<output-dir>/
├── source-{slug}.{ext}    # Source files
├── refs/                  # Reference images (if provided)
│   ├── ref-01-{slug}.{ext}
│   └── ref-01-{slug}.md   # Description file
├── prompts/cover.md       # Generation prompt
└── cover.png              # Output image

Slug: 2-4 words, kebab-case. Conflict: append -YYYYMMDD-HHMMSS

Workflow

Progress Checklist

Cover Image Progress:
- [ ] Step 0: Check preferences (EXTEND.md) ⛔ BLOCKING
- [ ] Step 1: Analyze content + save refs + determine output dir
- [ ] Step 2: Confirm options (6 dimensions) ⚠️ unless --quick
- [ ] Step 3: Create prompt
- [ ] Step 4: Generate image
- [ ] Step 5: Completion report

Flow

Input → [Step 0: Preferences] ─┬─ Found → Continue
                               └─ Not found → First-Time Setup ⛔ BLOCKING → Save EXTEND.md → Continue
        ↓
Analyze + Save Refs → [Output Dir] → [Confirm: 6 Dimensions] → Prompt → Generate → Complete
                                              ↓
                                     (skip if --quick or all specified)

Step 0: Load Preferences ⛔ BLOCKING

Check EXTEND.md in priority order — the first one found wins:

Priority	Path	Scope
1	.baoyu-skills/baoyu-cover-image/EXTEND.md	Project
2	${XDG_CONFIG_HOME:-$HOME/.config}/baoyu-skills/baoyu-cover-image/EXTEND.md	XDG
3	$HOME/.baoyu-skills/baoyu-cover-image/EXTEND.md	User home

Result	Action
Found	Load, display summary → Continue
Not found	⛔ Run first-time setup (references/config/first-time-setup.md) → Save → Continue

CRITICAL: If not found, complete setup BEFORE any other steps or questions.

Step 1: Analyze Content

1. Save reference images (if provided) → references/workflow/reference-images.md
2. Save source content (if pasted, save to source.md)
3. Analyze content: topic, tone, keywords, visual metaphors
4. Deep analyze references ⚠️: Extract specific, concrete elements (see reference-images.md)
5. Detect language: Compare source, user input, EXTEND.md preference
6. Determine output directory: Per File Structure rules

⚠️ People in Reference Images:

If reference images contain people who should appear in the cover:

• Model supports --ref (default): Copy image to refs/, pass via --ref at generation. No description file needed — the model sees the face directly.
• Model does NOT support --ref (Jimeng, Seedream 3.0): Create refs/ref-NN-{slug}.md with per-character description (hair, glasses, skin tone, clothing). Embed as MUST/REQUIRED instructions in prompt text.

See reference-images.md for full decision table.

Step 2: Confirm Options ⚠️

Hard gate: this step is mandatory per the Confirmation Policy — Steps 3–4 cannot start until the user confirms here (or explicitly opts out with --quick / quick_mode: true / equivalent wording in the current request).

MUST use AskUserQuestion tool to present options as interactive selection — NOT plain text tables. Present up to 4 questions in a single AskUserQuestion call (Type, Palette, Rendering, Font + Settings). Each question shows the recommended option first with reason, followed by alternatives.

Full confirmation flow and question format: references/workflow/confirm-options.md

Condition	Skipped	Still Asked
--quick or quick_mode: true	6 dimensions	Aspect ratio (unless --aspect)
All 6 + --aspect specified	All	None

Step 3: Create Prompt

Save to prompts/cover.md. Template: references/workflow/prompt-template.md

CRITICAL - References in Frontmatter:

• Files saved to refs/ → Add to frontmatter references list
• Style extracted verbally (no file) → Omit references, describe in body
• Before writing → Verify: test -f refs/ref-NN-{slug}.{ext}

Reference elements in body MUST be detailed, prefixed with "MUST"/"REQUIRED", with integration approach.

Step 4: Generate Image

1. Backup existing cover.png if regenerating
2. Select backend via the ## Image Generation Tools rule at the top: use whatever is available; if multiple, ask the user once. Do this once per session before any generation.
3. Write the full final prompt to prompts/01-cover-[slug].md (hard requirement) BEFORE invoking the backend.
4. Process references from prompt frontmatter:
   • direct usage → pass via --ref (use ref-capable backend)
   • style/palette → extract traits, append to prompt
5. Generate: Call the chosen backend with the prompt file, output path, aspect ratio.
   • codex-imagegen: see references/codex-imagegen.md for the invocation contract (preferred baoyu-image-gen --provider codex-cli path, runtime wrapper discovery, parameter notes, stdout schema, batch semantics).
   • Codex imagegen (native) or other runtime-native tools / baoyu-image-gen skill: per the rule in ## Image Generation Tools above.
6. On failure: auto-retry once

Step 5: Completion Report

Cover Generated!

Topic: [topic]
Type: [type] | Palette: [palette] | Rendering: [rendering]
Text: [text] | Mood: [mood] | Font: [font] | Aspect: [ratio]
Title: [title or "visual only"]
Language: [lang] | Watermark: [enabled/disabled]
References: [N images or "extracted style" or "none"]
Location: [directory path]

Files:
✓ source-{slug}.{ext}
✓ prompts/cover.md
✓ cover.png

Image Modification

Action	Steps
Regenerate	Backup → Update prompt file FIRST → Regenerate
Change dimension	Backup → Confirm new value → Update prompt → Regenerate

Text correction policy:

• If the title/subtitle is misspelled, garbled, hard to read, or visually weak, do not patch the bitmap with code.
• For text-correction regenerations, write a new prompt file and a new output path so the flawed candidate is preserved for comparison.
• Post-processing is limited to crop, resize, compression, or format conversion that does not alter text or the main composition.

Composition Principles

• Whitespace: 40-60% breathing room
• Visual anchor: Main element centered or offset left
• Characters: Simplified silhouettes; NO realistic humans
• Title: Use exact title from user/source; never invent

Changing Preferences

EXTEND.md lives at the path noted in Step 0. Three ways to change it:

• Edit directly — open EXTEND.md and change fields. Full schema: references/config/preferences-schema.md.
• Reconfigure interactively — delete EXTEND.md (or ask "reconfigure baoyu-cover-image preferences" / "重新配置"). The next run re-triggers first-time setup.
• Common one-line edits:
  • preferred_image_backend: auto — default; runtime-native tool wins, falls back to the only installed backend, asks only if multiple non-native are present.
  • preferred_image_backend: codex-imagegen — pin to Codex's built-in.
  • preferred_image_backend: baoyu-image-gen — pin to the baoyu-image-gen skill.
  • preferred_image_backend: ask — confirm backend every run.
  • watermark.enabled: true, preferred_type, preferred_palette, preferred_rendering, default_aspect, quick_mode: true, language — shift the auto-selection defaults and confirmation flow.

References

Dimensions: text.md | mood.md | font.md Palettes: references/palettes/ Renderings: references/renderings/ Types: references/types.md Auto-Selection: references/auto-selection.md Style Presets: references/style-presets.md Compatibility: references/compatibility.md Visual Elements: references/visual-elements.md Workflow: confirm-options.md | prompt-template.md | reference-images.md Config: preferences-schema.md | first-time-setup.md | watermark-guide.md