StoryWriter Agent

File	lib/agents/storyWriter.ts
Orchestrated by	lib/agents/storyOrchestrator.ts
Model	gemini-2.5-pro (Vertex AI)
Triggered by	Story generation — after SafetyGuardian approves

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What it does

Writes a complete children's story in the requested language and page count. Only runs after SafetyGuardian has approved the prompt. Produces story text per page plus an English image prompt for each page (used by the Illustrator agent).

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Tools

Tool	When called	Parameters
submit_story	Once, with the complete story	title: string, pages: Page[]

The agent calls submit_story exactly once with the full story JSON.

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Output structure

{
  "title": "Luna and the Golden Key",
  "pages": [
    {
      "pageNumber": 1,
      "text": "Story text in the target language...",
      "imagePrompt": "Detailed English illustration prompt for Imagen..."
    },
    {
      "pageNumber": 2,
      "text": "...",
      "imagePrompt": "..."
    }
  ]
}

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Rules enforced by the agent prompt

• Story text is written in the target language (Indonesian, French, Portuguese, etc.)
• imagePrompt is always in English — required by Imagen for image generation
• Page count is 4–6 depending on pageCount input (clamped: min 4, max 6)
• Content is age-appropriate for 5–12, positive endings, simple vocabulary
• Each page text is 2–4 sentences, suitable for one storybook page

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Supported languages

Code	Language
en	English
id	Indonesian
es	Spanish
fr	French
pt	Portuguese (Brazil)
pt_pt	Portuguese (Portugal)
de	German
it	Italian
ja	Japanese
ko	Korean
zh	Chinese (Simplified)
ar	Arabic
hi	Hindi
ru	Russian
vi	Vietnamese
ms	Malay
fil	Filipino
tet	Tetum
my	Burmese (Myanmar)
lo	Lao
km	Khmer (Cambodia)

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Flow

StoryOrchestrator (after SafetyGuardian approves)
    │
    ▼
StoryWriter LLM call
    │
    └── submit_story({ title, pages[] })
            │
            ▼
    JSON extracted → returned to orchestrator
            │
            ▼
    Pages sent to Illustrator + Narrator (parallel)

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Observability span

Span name: agent/StoryWriter

Attribute	Example value
agent.name	StoryWriter
agent.model	gemini-2.5-pro
agent.language	id
agent.pageCount	5
agent.pages_generated	5
agent.success	true
agent.duration_ms	14200

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Simulation test cases

Run with npm run simulate:

Scenario	Expected
English story — valid structure	title + pages[], all fields present
Indonesian story	Story text contains Indonesian words
Exact page count — 5 pages	pages.length === 5
Non-English story — image prompts in English	imagePrompt contains English words