docs(image-generation): emphasize Codex imagegen priority and forbid SVG/HTML substitution

Strengthen the shared image-generation backend selection rule:
- Codex `imagegen` MUST be used when listed in the available-skills inventory;
  invoke via the `Skill` tool with `skill: "imagegen"`.
- Never substitute SVG, HTML, canvas, or other code-based rendering when no
  raster backend can be resolved — fall through and ask the user instead.

Applied to docs/image-generation-tools.md and inlined into baoyu-article-illustrator
(plus its references/workflow.md), baoyu-comic, baoyu-cover-image, baoyu-image-cards,
baoyu-infographic, baoyu-slide-deck, baoyu-xhs-images per the self-containment rule.

docs/image-generation-tools.md

@@ -9,11 +9,14 @@ When a 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 the skill's `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):
-   - If the current runtime exposes a native image tool (e.g., Codex `imagegen`, Hermes `image_generate`), use it. Runtime-native tools are preferred by default — agents that know their own tool inventory should surface the native one here.
+   - **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-imagine`) unless the user has explicitly pinned a different `preferred_image_backend`.
+   - **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-imagine`), 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.
+
 Setting `preferred_image_backend: ask` forces the step-3 prompt every run regardless of available backends.
 
 ## The Preference Field

skills/baoyu-article-illustrator/SKILL.md

@@ -28,11 +28,14 @@ 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):
-   - If the current runtime exposes a native image tool (e.g., Codex `imagegen`, Hermes `image_generate`), use it. Runtime-native tools are preferred by default — agents that know their own tool inventory should surface the native one here.
+   - **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-imagine`) unless the user has explicitly pinned a different `preferred_image_backend`.
+   - **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-imagine`), 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.
+
 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.

skills/baoyu-article-illustrator/references/workflow.md

@@ -345,7 +345,14 @@ Prompt Files:
 
 ### 5.2 Select Generation Skill
 
-Check available skills. If multiple, ask user.
+Follow the `## Image Generation Tools` rule at the top of `SKILL.md`. Concretely:
+
+- If `imagegen` is in your available-skills list (Codex), use it — invoke via the `Skill` tool with `skill: "imagegen"`.
+- Else if the EXTEND.md pin is available, use it.
+- Else if exactly one non-native backend is installed, use it.
+- Else, ask the user.
+
+**Do not generate SVG, HTML, or any code-based vector as a substitute for the raster image.** If no raster backend can be resolved, ask the user how to proceed.
 
 ### 5.3 Process References ⚠️ REQUIRED if references saved in Step 1.0
 

skills/baoyu-comic/SKILL.md

@@ -32,11 +32,14 @@ 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):
-   - If the current runtime exposes a native image tool (e.g., Codex `imagegen`, Hermes `image_generate`), use it. Runtime-native tools are preferred by default — agents that know their own tool inventory should surface the native one here.
+   - **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-imagine`) unless the user has explicitly pinned a different `preferred_image_backend`.
+   - **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-imagine`), 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.
+
 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.

skills/baoyu-cover-image/SKILL.md

@@ -28,11 +28,14 @@ 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):
-   - If the current runtime exposes a native image tool (e.g., Codex `imagegen`, Hermes `image_generate`), use it. Runtime-native tools are preferred by default — agents that know their own tool inventory should surface the native one here.
+   - **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-imagine`) unless the user has explicitly pinned a different `preferred_image_backend`.
+   - **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-imagine`), 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.
+
 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.

skills/baoyu-image-cards/SKILL.md

@@ -28,11 +28,14 @@ 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):
-   - If the current runtime exposes a native image tool (e.g., Codex `imagegen`, Hermes `image_generate`), use it. Runtime-native tools are preferred by default — agents that know their own tool inventory should surface the native one here.
+   - **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-imagine`) unless the user has explicitly pinned a different `preferred_image_backend`.
+   - **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-imagine`), 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.
+
 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 file is the reproducibility record and lets you switch backends without regenerating prompts.

skills/baoyu-infographic/SKILL.md

@@ -28,11 +28,14 @@ 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):
-   - If the current runtime exposes a native image tool (e.g., Codex `imagegen`, Hermes `image_generate`), use it. Runtime-native tools are preferred by default — agents that know their own tool inventory should surface the native one here.
+   - **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-imagine`) unless the user has explicitly pinned a different `preferred_image_backend`.
+   - **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-imagine`), 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.
+
 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.

skills/baoyu-slide-deck/SKILL.md

@@ -32,11 +32,14 @@ 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):
-   - If the current runtime exposes a native image tool (e.g., Codex `imagegen`, Hermes `image_generate`), use it. Runtime-native tools are preferred by default — agents that know their own tool inventory should surface the native one here.
+   - **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-imagine`) unless the user has explicitly pinned a different `preferred_image_backend`.
+   - **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-imagine`), 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.
+
 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-slide-[slug].md`) BEFORE invoking any backend. The file is the reproducibility record and lets you switch backends without regenerating prompts.

skills/baoyu-xhs-images/SKILL.md

@@ -29,11 +29,14 @@ 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):
-   - If the current runtime exposes a native image tool (e.g., Codex `imagegen`, Hermes `image_generate`), use it. Runtime-native tools are preferred by default — agents that know their own tool inventory should surface the native one here.
+   - **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-imagine`) unless the user has explicitly pinned a different `preferred_image_backend`.
+   - **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-imagine`), 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.
+
 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 file is the reproducibility record and lets you switch backends without regenerating prompts.