feat(ai): automate end-to-end PRD, architecture, and task generation directly from Objective

vibn-frontend/app/api/projects/[projectId]/plan/generate/route.ts

@@ -0,0 +1,172 @@
+import { NextResponse } from "next/server";
+import { authSession } from "@/lib/auth/session-server";
+import { query, queryOne } from "@/lib/db-postgres";
+import { callVibnChat } from "@/lib/ai/vibn-chat-model";
+
+// Generate a complete PRD, Tech Architecture, and Execution Plan based on the objective
+
+export async function POST(
+  req: Request,
+  ctx: { params: Promise<{ projectId: string }> }
+) {
+  const { projectId } = await ctx.params;
+  const session = await authSession();
+  if (!session?.user?.email) {
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+  }
+
+  const projectRow = await queryOne<{ data: any; slug: string }>(
+    `SELECT data, slug FROM fs_projects
+     JOIN fs_users u ON u.id = fs_projects.user_id
+     WHERE fs_projects.id = $1 AND u.data->>'email' = $2 LIMIT 1`,
+    [projectId, session.user.email]
+  );
+  if (!projectRow) return NextResponse.json({ error: "Project not found" }, { status: 404 });
+
+  const body = await req.json().catch(() => ({}));
+  const objective = String(body.objective || projectRow.data?.plan?.vision || "").trim();
+
+  if (!objective) {
+    return NextResponse.json({ error: "Objective is required to generate a PRD." }, { status: 400 });
+  }
+
+  // We run three sequential LLM calls to construct the complete Spec Kit documentation
+
+  // 1. Generate the Product Spec (User Stories & Requirements)
+  const specPrompt = `You are a Principal Product Manager writing a Product Requirements Document (PRD).
+Based on the following Objective, generate a structured PRD using Markdown.
+DO NOT talk about technology (databases, frameworks, APIs). Focus purely on user value and capabilities.
+
+OBJECTIVE:
+${objective}
+
+You MUST follow this exact structure:
+
+## User Scenarios & Testing
+List the 3-5 most critical User Stories, prioritized.
+### User Story 1 - [Brief Title] (Priority: P1)
+[Description]
+**Acceptance Scenarios**:
+1. **Given** [state], **When** [action], **Then** [outcome]
+
+### User Story 2 - [Brief Title] (Priority: P2)
+[Repeat...]
+
+## Functional Requirements
+- **FR-001**: System MUST [capability]
+- **FR-002**: Users MUST be able to [interaction]
+
+## Success Criteria
+- **SC-001**: [Measurable business outcome]`;
+
+  const specResponse = await callVibnChat({
+    systemPrompt: specPrompt,
+    messages: [{ role: "user", content: "Generate the PRD." }],
+    temperature: 0.2
+  });
+  const specMd = specResponse.text || "Failed to generate PRD.";
+
+  // 2. Generate the Technical Architecture (Plan)
+  const planPrompt = `You are a Principal Software Architect.
+Based on the following PRD, define the Technical Architecture required to build it.
+Your choices must default to: Next.js (App Router), Postgres, Tailwind CSS, NextAuth, and Stripe (if payments).
+
+PRD:
+${specMd}
+
+You MUST follow this exact structure:
+
+## Technical Context
+- **Language/Framework**: Next.js 15 (App Router), TypeScript
+- **Database**: Postgres (via Prisma or raw SQL)
+- **Styling**: Tailwind CSS
+- **Authentication**: [Decide auth strategy]
+
+## Data Model
+List the core database tables and their relationships.
+- **[EntityName]**: [fields...]
+
+## File Structure
+Provide a high-level file tree representing the required Next.js pages and API routes.
+\`\`\`text
+src/app/
+  page.tsx
+  api/
+\`\`\``;
+
+  const planResponse = await callVibnChat({
+    systemPrompt: planPrompt,
+    messages: [{ role: "user", content: "Generate the Technical Architecture." }],
+    temperature: 0.1
+  });
+  const planMd = planResponse.text || "Failed to generate Architecture.";
+
+  // 3. Generate the Execution Plan (Tasks)
+  const tasksPrompt = `You are a Technical Project Manager.
+Based on the PRD and Technical Architecture, break the implementation down into an atomic, dependency-ordered Task List.
+You MUST format each task EXACTLY as a markdown bullet with a checkbox, a phase tag, and a description containing the file paths.
+
+PRD:
+${specMd}
+
+ARCHITECTURE:
+${planMd}
+
+You MUST follow this exact structure:
+
+## Phase 1: Setup & Foundation
+- [ ] [Phase 1] Initialize Next.js project and layout
+- [ ] [Phase 1] Setup Postgres database schema
+
+## Phase 2: [User Story 1 Title]
+- [ ] [US1] Build API route for [feature]
+- [ ] [US1] Build frontend UI component in src/app/[route]/page.tsx
+
+## Phase 3: [User Story 2 Title]
+- [ ] [US2] ...`;
+
+  const tasksResponse = await callVibnChat({
+    systemPrompt: tasksPrompt,
+    messages: [{ role: "user", content: "Generate the Execution Plan tasks." }],
+    temperature: 0.1
+  });
+  const tasksMd = tasksResponse.text || "";
+
+  // 4. Parse the tasks string into the JSON array expected by the DB
+  // Extract all `- [ ] [Group] Task description` lines
+  const taskLines = tasksMd.match(/- \[[ x]\] \[(.*?)\] (.*)/g) || [];
+  const parsedTasks = taskLines.map(line => {
+    const match = line.match(/- \[[ x]\] \[(.*?)\] (.*)/);
+    if (!match) return null;
+    return {
+      id: Math.random().toString(36).slice(2, 11),
+      title: `[${match[1]}] ${match[2]}`, // Fixed backticks
+      description: "",
+      status: "open",
+      createdAt: new Date().toISOString()
+    };
+  }).filter(Boolean);
+
+  // 5. Update the Database Plan
+  const currentPlan = projectRow.data?.plan || {};
+  
+  // Save the PRD under decisions (we can render it specially in the UI)
+  const newDecisions = [
+    { id: "prd_spec", title: "Product Specification", choice: "Auto-generated PRD", why: specMd },
+    { id: "prd_arch", title: "Technical Architecture", choice: "Auto-generated Plan", why: planMd }
+  ];
+
+  const updatedPlan = {
+    ...currentPlan,
+    vision: objective,
+    tasks: parsedTasks.length > 0 ? parsedTasks : currentPlan.tasks,
+    decisions: newDecisions
+  };
+
+  await query(
+    `UPDATE fs_projects SET data = jsonb_set(data, '{plan}', $2::jsonb) WHERE id = $1`,
+    [projectId, JSON.stringify(updatedPlan)]
+  );
+
+  return NextResponse.json({ plan: updatedPlan });
+}