docs(baoyu-article-illustrator,baoyu-comic,baoyu-infographic,baoyu-slide-deck,baoyu-xhs-images): point codex-imagegen flow at baoyu-image-gen --provider codex-cli

Add a `Codex via codex exec` branch to each skill's backend-selection
ladder and ship a per-skill references/codex-imagegen.md with the
invocation contract (preferred baoyu-image-gen --provider codex-cli
path, direct-wrapper fallback, parameter notes, stdout schema, batch
semantics).

skills/baoyu-comic/SKILL.md

@@ -1,7 +1,7 @@
 ---
 name: baoyu-comic
 description: Knowledge comic creator supporting multiple art styles and tones. Creates original educational comics with detailed panel layouts and batch-capable image generation. Use when user asks to create "知识漫画", "教育漫画", "biography comic", "tutorial comic", or "Logicomix-style comic".
-version: 1.117.3
+version: 1.117.4
 metadata:
   openclaw:
     homepage: https://github.com/JimLiu/baoyu-skills#baoyu-comic
@@ -33,6 +33,7 @@ When this skill needs to render an image, resolve the backend in this order:
 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](references/codex-imagegen.md) — load that file only when this branch is selected.
    - **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.
@@ -247,6 +248,8 @@ Analyze → [Check Existing?] → [Confirm: Style + Reviews] → Storyboard →
 
 **Pick a backend once per session** using the `## Image Generation Tools` rule at the top. If the backend is a repo skill (e.g., `baoyu-image-gen`), read its `SKILL.md` and use its documented interface rather than its scripts.
 
+**`codex-imagegen` invocation**: when the rule resolves to `codex-imagegen`, see [references/codex-imagegen.md](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 — n=1 per call so page batches must dispatch one wrapper call per page).
+
 **7.1 Character sheet** — generate it (to `characters/characters.png`, aspect `4:3`) when the comic is multi-page with recurring characters. Skip for simple presets (e.g., four-panel minimalist) or single-page comics. Compress to JPEG before use-as-`--ref` (`sips -s format jpeg -s formatOptions 80 …` on macOS, `pngquant --quality=65-80 …` elsewhere) to avoid payload failures. The prompt file at `characters/characters.md` must exist before invoking the backend.
 
 **7.2 Pages** — each page's prompt MUST already be at `prompts/NN-{cover|page}-[slug].md` before invoking the backend; the file is the reproducibility record. Strategy depends on the character sheet:

skills/baoyu-comic/references/codex-imagegen.md

@@ -0,0 +1,65 @@
+# `codex-imagegen` Wrapper Invocation
+
+Load this reference only when the [Image Generation Tools](../SKILL.md#image-generation-tools) rule has resolved to `codex-imagegen` — i.e., the current runtime exposes no native `imagegen` skill but `codex` CLI is on `PATH` with an active `codex login`.
+
+## Preferred path: route through `baoyu-image-gen`
+
+If the `baoyu-image-gen` skill is available in this runtime, **always** invoke through it rather than calling the wrapper directly. It handles retry/cache/batch/EXTEND.md preferences uniformly with every other provider.
+
+```bash
+${BUN_X} <baoyu-image-gen-base>/scripts/main.ts \
+  --provider codex-cli \
+  --image <ABSOLUTE_output> \
+  --promptfiles <ABSOLUTE_prompts/NN-{cover|page}-[slug].md> \
+  --ar <ratio> \
+  [--ref <ABSOLUTE_file>]...
+```
+
+Resolve `<baoyu-image-gen-base>` the same way you resolve any sibling skill — through your runtime's skill registry (`Skill` tool, plugin marketplace, or `$HOME/.baoyu-skills/baoyu-image-gen/`).
+
+## Fallback: spawn the wrapper directly
+
+Only when `baoyu-image-gen` is NOT installed in the current runtime. Discover the wrapper's location at runtime — do NOT hard-code `../../packages/...` from this skill:
+
+1. **Honor explicit override**: if `$BAOYU_CODEX_IMAGEGEN_BIN` is set and points to a real file, use that path. It may be `.ts` (spawn `bun <path>`) or `.sh`/binary (spawn directly).
+2. **Search the plugin root**: walk up from this skill's directory looking for `packages/baoyu-codex-imagegen/src/main.ts`. If found, that is the wrapper. Spawn it with `bun`.
+3. **Last resort**: tell the user that `codex-imagegen` is not available in this runtime and ask whether to install the `baoyu-skills` plugin (or set `BAOYU_CODEX_IMAGEGEN_BIN`) or pick another backend.
+
+Once located, the invocation shape is:
+
+```bash
+bun <WRAPPER>/main.ts \
+  --image <ABSOLUTE_output> \
+  --prompt-file <ABSOLUTE_prompts/NN-{cover|page}-[slug].md> \
+  --aspect <ratio> \
+  [--ref <ABSOLUTE_file>]... \
+  [--timeout <ms>] \
+  [--cache-dir ~/.cache/baoyu-codex-imagegen] \
+  [--log-file <ABSOLUTE_jsonl_log_path>]
+```
+
+If `bun` is missing, `npx -y bun <WRAPPER>/main.ts ...` works as a fallback.
+
+## Parameter notes
+
+- **All filesystem inputs** are auto-resolved against `process.cwd()` when relative, but agents should pass absolute paths to be robust against cwd drift.
+- **`--timeout`** defaults to `300000` (5 min) per `codex exec` attempt. Raise (e.g. `--timeout 600000` for 10 min) on slow networks or large prompts.
+- **`--cache-dir`** is off by default. Enable for repeatable runs to skip redundant generations of the same prompt+aspect+refs.
+- **Authentication**: the wrapper uses the user's Codex subscription — no `OPENAI_API_KEY` is read or sent.
+
+## Stdout contract
+
+Single JSON line:
+
+- Success: `{"status":"ok","path":"...","bytes":N,"elapsed_seconds":N,"thread_id":"...","attempts":N,"cached":bool,...}`
+- Failure: `{"status":"error","path":"...","bytes":0,"error":"...","error_kind":"..."}`
+
+`error_kind` values: `codex_not_installed`, `invalid_args`, `prompt_file_missing`, `spawn_failed`, `timeout`, `no_image_gen_tool_use`, `output_missing`, `invalid_png`, `agent_refused`, `lock_busy`.
+
+On retryable errors (timeout, spawn_failed, no_image_gen_tool_use, output_missing, invalid_png, agent_refused), ask the user whether to retry or fall back to another backend.
+
+## Batch semantics
+
+- Codex `image_gen` returns **one image per call** (`n=1` only). Multi-image jobs must dispatch one wrapper call per image.
+- The wrapper does NOT accept a `--sessionId` flag. Chain/scene consistency must come from `--ref` reference images.
+- `--size` and `--quality` are silently ignored — Codex picks pixel dimensions from `--aspect`.