Spec Driven Development The End Of Vibe Coding Daniel Sogl [email protected] Principal Consultant | Speaker 

Daniel Sogl Spec Driven Development The End Of Vibe Coding About me Principal Consultant @ Thinktecture AG Focus Developer Productivity & Gen AI MVP Developer & Web Technologies Socials linktr.ee/daniel_sogl 

AI Agents Fail More Than You Think Spec Driven Development The End Of Vibe Coding The Problem Sources: SWE-Bench Pro (Sep 2025), Stack Overflow Survey 2025, CodeRabbit Report (Dec 2025) <25% SWE-Bench Pro Score 66% Spent More Time Fixing 2.74x Security Vulnerabilities 

Spec Driven Development The End Of Vibe Coding Five Core Limitations Of AI Coding Agents Context Management Lost in the middle problem Multi-File Coordination No dependency graphs Silent Failures Removes safety checks, fakes data Architecture Decisions Sees structure, not trade-offs Enterprise Context Misses implicit business logic 

Four Mechanisms How Specs Improve AI Spec Driven Development The End Of Vibe Coding Spec Driven Development Treat AI agents like literal-minded pair programmers, not search engines Complete Context Agent gets full picture upfront 1 Structured Reasoning Reduces hallucinations 2 Validation Checkpoints Humans verify before proceeding 3 Autonomous Implementation Specs + tests = guardrails 4 

What is Spec Driven Development (SDD)? Spec Driven Development The End Of Vibe Coding Spec Driven Development SDD is a development methodology where detailed specifications drive the entire development process — especially the collaboration with AI coding agents. Spec First Write the specification before any code AI-Optimized Specs give AI agents full context upfront Iterative Specs evolve alongside the project Consistency Uniform architecture across all features 1 2 3 4 

Spec Driven Development The End Of Vibe Coding How SDD Relates to TDD and BDD SDD Spec Driven Development What & Why Intent Level Human writes intent BDD Behavior Driven Development System Behavior Feature Level Given / When / Then TDD Test Driven Development Code Correctness Unit Level Red / Green / Refactor 

Real Results Spec Driven Development The End Of Vibe Coding Practical Implementation 250k Developers in 3 Months AWS Kiro - The New Stack 94% Satisfaction Score Delta Airlines (re:Invent) 16k+ Spec Kit Stars in Week 1 GitHub (Sept 2025) Specs are the new code. 80-90% of our work as programmers is structured communication Sean Grove, OpenAI Sources: AWS Kiro, AWS re:invent (2025), The New Code – AI Engineer (2025) 

Walking Through the 4 Phases Spec Driven Development The End Of Vibe Coding SDD In Action 1 Specify Define intent, constraints, acceptance criteria 2 Plan AI generates architecture from spec 3 Task Atomic, parallel work items 4 Implement Execute with spec as guardrails YOU AI + YOU AI AI 

Three approaches, one goal Spec Driven Development The End Of Vibe Coding SDD Tooling Landscape Choose your tool based on project type, team size, and preferred workflow. GitHub Spec Kit Open-source CLI, agent- agnostic Specify → Plan → Tasks Best for greenfield projects 1 OpenSpec Lightweight, iterative framework Propose → Apply → Archive Best for brownfield codebases 2 Kiro (AWS) Full IDE with built-in SDD Requirements → Design → Tasks Best for enterprise teams 3 

Your Repo, Your Rules Spec Driven Development The End Of Vibe Coding Setting Up SDD Three files to add to your repo — everything lives in version control. Constitution Project-level rules: tech stack, conventions, boundaries. Lives in repo root as CONSTITUTION.md 1 Specs Directory One Markdown file per feature in .specs/ folder. Plans & tasks generated alongside each spec. 2 Agent Config CLAUDE.md or .cursorrules Points agent to constitution & spec workflow. 3 

What Makes a Good Specification Spec Driven Development The End Of Vibe Coding Anatomy of a Spec A spec is a structured Markdown document that captures the three pillars every AI agent needs to succeed. Intent What should be built and why? Describes the goal, user story, and motivation behind the feature. Constraints Tech stack, patterns, and boundaries the agent must follow. Prevents architectural drift. Acceptance Criteria Concrete, testable conditions that define done. The agent validates its own output against these. 1 2 3 

Do's & Don'ts Spec Driven Development The End Of Vibe Coding Writing Good Specs ✓ Do ✗ Don't • Be specific about behavior and edge cases • Define explicit acceptance criteria • List constraints: what NOT to do • Reference existing code patterns • Include error handling expectations • Describe implementation details • Write vague requirements ("make it fast") • Assume the agent knows your codebase • Mix multiple features in one spec • Skip non-functional requirements 

Boundaries Before Code Spec Driven Development The End Of Vibe Coding Constitution Design & Development • Test-First (BDD / Gherkin) • DDD + SOLID Principles • API-First, Mobile-First • Ubiquitous Language Architecture & Quality • Vertical Slice Architecture • Security + Observability by Default • Definition of Done • Dependency Management Mandatory Workflow Specify → Contract → Plan → Tasks → Red → Green → Refactor → Review 

The only file you write by hand "As a user I want a SPA to search and explore Pokémon." • Search & Discovery • Pokémon Cards • Detail View • Loading & Error Handling Spec Driven Development The End Of Vibe Coding The Spec 

From spec + prompt to a full architecture plan Input: Spec + Prompt • Tech stack, testing, CI/CD Output: Architecture Plan • Components, data flow, files Review + approve before coding. Spec Driven Development The End Of Vibe Coding The Plan 

Atomic, parallel, ready to execute Atomic work units • One task = one file, one concern • Explicit dependencies, parallel execution Each task includes • Description, affected files, acceptance criteria • Test commands for self-validation Spec Driven Development The End Of Vibe Coding The Tasks 

All green. Spec validated. Agent executes against the spec • Sequential tasks, respects dependencies • Self-validates via tests after each task The result • All tests green — spec fully validated • Ready for human code review Spec Driven Development The End Of Vibe Coding Implementation 

Spec → Plan → Tasks → Running Code Spec Driven Development The End Of Vibe Coding Live Coding Feed Spec Hand Pokémon spec to the AI agent Watch Execution Agent plans, creates tasks, implements Review Output Review generated code against the spec All Green Tests pass, working Pokémon app LIVE DEMO 1 2 3 4 

Spec Driven Development The End Of Vibe Coding Where SDD Excels Greenfield Projects Spec becomes single source of truth Complex Features Agents need structure to avoid breaking contracts Multi-Agent Coordination Specs prevent conflicting implementations Compliance & Audit Specs as traceable control surfaces Rule of thumb: If it takes 2+ prompts to explain, write a spec. 

Know the Limits Spec Driven Development The End Of Vibe Coding When NOT to Use SDD Small Bug Fixes Spec overhead exceeds the change Rapid Prototyping Uncertain requirements — specs need clarity UI-Heavy / Creative Work Visual design needs iteration, not specs One-Off Scripts Throwaway code — just vibe code it Rule of thumb: If you can explain the task in one sentence, skip the spec. 

What to remember from this talk Spec Driven Development The End Of Vibe Coding Key Takeaways AI agents are powerful but limited — <25% success on realistic tasks SDD: Intent as truth, not code as truth — Specs drive everything Specifications become executable through AI — From docs to working software Choose your tool: Spec Kit · OpenSpec · Kiro — Greenfield · Brownfield · Enterprise Industry convergence on structured intent — SDD is becoming standard practice 

Spec Driven Development The End Of Vibe Coding “ ” Exceptional at pattern completion, not at mind reading. — Den Delimarsky, GitHub Principal PM 

Thanks for your attention Daniel Sogl https://linktr.ee/daniel_sogl