Mastering Local Spec-Driven Development

Beyond Vibe Coding: Mastering Local Spec-Driven Development

With GitHub Spec-Kit and Ollama

🚀

Spec-Kit + Ollama

Privacy-first, Engineering-led AI Development

The era of AI-assisted software development is moving fast. First came autocomplete, then came chat, and lately, the developer community has been swept up in the concept of "vibe coding"—the practice of describing what you want in loose, natural language and letting an AI agent figure out the entire implementation.

While vibe coding feels like magic for quick scripts and prototypes, it quickly breaks down when building complex, production-ready software. Without architectural direction or clear constraints, AI agents often write brittle code, hallucinate APIs, or lose the plot entirely.

To build reliable software with AI, we need to bridge the gap between creative "vibes" and engineering discipline. Enter Specification-Driven Development (SDD) with GitHub's Spec-Kit, powered by the ultimate local AI engine: Ollama.

What is Spec-Driven Development (SDD)?

Spec-Driven Development flips the traditional AI coding script. Instead of treating software specifications as disposable scaffolding, SDD makes them the central, executable source of truth.

[ Diagram: Specification-Driven Development Lifecycle ]

Constitution

→

Specify

→

Plan

→

Analyze

→

Implement

GitHub’s open-source Spec-Kit provides a framework to standardize this process through predictable phases:

/speckit.constitution

Defines project governing principles, coding standards, and UI/UX constraints.

/speckit.specify

Details the specific feature requirements and user stories.

/speckit.plan

Generates a technical implementation plan and architecture based on your stack.

/speckit.analyze

Runs rigorous cross-artifact consistency checks before writing code.

/speckit.implement

Executes the verified plan and tasks sequentially to generate high-quality code that satisfies all constraints.

Why Run Models Locally?

Absolute Privacy

Proprietary source code and API keys never leave your machine.

Zero Cost

Stop watching API bills skyrocket during complex debugging loops.

Offline Capability

Code from anywhere without relying on an active internet connection.

Total Control

Models are immutable until you decide to update them.

Preparing Your Local Engine

Create a custom Modelfile for high precision and large context support:

# Start from a strong base coding model
FROM qwen2.5-coder:32b

# Coding requires high precision
PARAMETER temperature 0.1

# Set context window to 64k tokens
PARAMETER num_ctx 65536

SYSTEM """
You are an expert software architect executing SDD. 
Adhere strictly to project constitution and specifications.
"""

$ ollama create local-spec-coder -f Modelfile

Hooking Up Spec-Kit

To connect AI agents to local models, Ollama provides the powerful ollama launch command, which handles API routing automatically.

1. Claude Code Integration

$ specify init . --ai claude
$ ollama launch claude --model local-spec-coder

Ollama intercepts API calls and injects dummy keys to drop you instantly into the interactive terminal.

2. Codex CLI Integration

$ specify init . --ai codex
$ ollama launch codex --model local-spec-coder

Ollama manages the config.toml updates required to register your local provider.

3. OpenCode Integration

$ specify init . --ai opencode
$ ollama launch opencode --model local-spec-coder

Generates the proper provider block inside OpenCode's configuration JSON automatically.