Add AI-assisted world and character drafting flows

apps/web/server/api/v1/campaigns/[id]/characters/suggest.post.ts

@@ -0,0 +1,77 @@
+import { CharacterDraftSchema } from '@dng/shared'
+import { z } from 'zod'
+import { buildJsonCompletion, parseJsonCompletion } from '~/server/utils/ai-provider'
+import {
+  requireCampaignAccess,
+  requireStageTwoSafeText,
+  requireStageTwoUser,
+  stageTwoApiError,
+  stageTwoDatabase,
+  stageTwoUuid,
+} from '~/server/utils/stage-two-supabase'
+
+const BodySchema = z.object({
+  concept: z.string().trim().max(600).default(''),
+  controller: z.enum(['human', 'ai']).default('human'),
+}).strict()
+
+export default defineEventHandler(async (event) => {
+  try {
+    const user = await requireStageTwoUser(event)
+    const campaignId = stageTwoUuid(getRouterParam(event, 'id'), 'campaign id')
+    const access = await requireCampaignAccess(campaignId, user.id)
+    const body = BodySchema.parse((await readBody(event)) ?? {})
+    if (body.controller === 'ai' && !access.owner) {
+      throw createError({ statusCode: 403, statusMessage: 'Only the campaign owner can add AI heroes.' })
+    }
+    if (body.concept) requireStageTwoSafeText(body.concept)
+
+    const worlds = await stageTwoDatabase<Array<Record<string, unknown>>>(
+      `worlds?select=title,genre,tone,premise,content_boundaries&` +
+      `id=eq.${String(access.campaign.world_id)}&limit=1`,
+    )
+    const world = worlds[0]
+    if (!world) throw createError({ statusCode: 404, statusMessage: 'Campaign world not found.' })
+
+    const completion = buildJsonCompletion(useRuntimeConfig(), {
+      system: `You create an original, editable Dungeons & Ground character draft for a private 13+ TTRPG campaign. Adapt archetype, equipment and voice to the supplied genre, but always use STR, DEX, CON, INT, WIS and CHA. Keep an alpha hero grounded: ability scores 7–16, max HP 8–20, Defense 10–16, proficiency 2. Give 2–5 useful starting items and a distinctive persona. Never use protected franchise characters. Return only the requested JSON.`,
+      messages: [{
+        role: 'user',
+        content: JSON.stringify({
+          world,
+          currentScene: access.campaign.current_scene,
+          heroKind: body.controller === 'ai' ? 'persistent AI companion' : 'human player character',
+          requestedConcept: body.concept || 'Surprise me with a character who creates interesting choices for this party.',
+        }),
+      }],
+      schemaName: 'character_draft',
+      jsonSchema: CharacterDraftSchema.toJSONSchema(),
+    })
+
+    const controller = new AbortController()
+    const timeout = setTimeout(() => controller.abort(), 30_000)
+    let response: Response
+    try {
+      response = await fetch(completion.endpoint, {
+        method: 'POST',
+        headers: completion.headers,
+        body: JSON.stringify(completion.body),
+        signal: controller.signal,
+      })
+    } finally {
+      clearTimeout(timeout)
+    }
+    if (!response.ok) throw createError({ statusCode: 502, statusMessage: 'The character coauthor is temporarily unavailable.' })
+
+    let character
+    try {
+      character = CharacterDraftSchema.parse(parseJsonCompletion(await response.json()))
+    } catch {
+      throw createError({ statusCode: 502, statusMessage: 'The coauthor returned an invalid character draft.' })
+    }
+    requireStageTwoSafeText(JSON.stringify(character))
+    return { character }
+  } catch (error) {
+    stageTwoApiError(error)
+  }
+})