Spec-Driven Development (SDD)

Measure twice, code once.

Spec-Driven Development (SDD) is a built-in methodology for Gemini CLI that enables Context-Driven Development. Inspired by Conductor, it turns Gemini CLI into a proactive project manager that follows a strict protocol to specify, plan, and implement software features and bug fixes.

Instead of just writing code, SDD ensures a consistent, high-quality lifecycle for every task: Context -> Spec & Plan -> Implement.

The philosophy behind SDD is simple: control your code. By treating context as a managed artifact alongside your code, you transform your repository into a single source of truth that drives every agent interaction with deep, persistent project awareness.

Features

Plan before you build: Create specs and plans that guide the agent for new and existing codebases.
Maintain context: Ensure AI follows style guides, tech stack choices, and product goals.
Iterate safely: Review plans before code is written, keeping you firmly in the loop.
Work as a team: Set project-level context for your product, tech stack, and workflow preferences that become a shared foundation for your team.
Build on existing projects: Intelligent initialization for both new (Greenfield) and existing (Brownfield) projects.
Smart revert: A git-aware revert command that understands logical units of work (tracks, phases, tasks) rather than just commit hashes.

Usage

SDD is designed to manage the entire lifecycle of your development tasks. It is one of the planning workflows supported by Gemini CLI.

Enabling SDD

SDD is currently an experimental feature. To use it, you must enable the experimental.sdd flag in your settings:

Open the settings dialog by running /settings.
Press / to enter search mode and type SDD.
Enable Spec-Driven Development (SDD).
Restart the CLI for the changes to take effect.

Alternatively, you can navigate to the Experimental category to find the setting, or enable it manually in your ~/.gemini/settings.json file:

{
  "experimental": {
    "sdd": true
  }
}

Note on Token Consumption: SDD's context-driven approach involves reading and analyzing your project's context, specifications, and plans. This can lead to increased token consumption, especially in larger projects or during extensive planning and implementation phases. You can check the token consumption in the current session by running /stats model.

1. Set Up the Project (Run Once)

When you run /spec setup, SDD helps you define the core components of your project context. This context is then used for building new components or features by you or anyone on your team.

Product: Define project context (e.g. users, product goals, high-level features).
Product guidelines: Define standards (e.g. prose style, brand messaging, visual identity).
Tech stack: Configure technical preferences (e.g. language, database, frameworks).
Workflow: Set team preferences (e.g. TDD, commit strategy).

Generated Artifacts:

.gemini/specs/product.md
.gemini/specs/product-guidelines.md
.gemini/specs/tech-stack.md
.gemini/specs/workflow.md
.gemini/specs/code_styleguides/
.gemini/specs/tracks.md

/spec setup

2. Start a New Track (Feature or Bug)

When you’re ready to take on a new feature or bug fix, run /spec create. This initializes a track — a high-level unit of work. SDD helps you generate two critical artifacts:

Specs: The detailed requirements for the specific job. What are we building and why?
Plan: An actionable to-do list containing phases, tasks, and sub-tasks.

Generated Artifacts:

.gemini/specs/tracks/<track_id>/spec.md
.gemini/specs/tracks/<track_id>/plan.md
.gemini/specs/tracks/<track_id>/metadata.json

/spec create
# OR with a description
/spec create "Add a dark mode toggle to the settings page"

3. Implement the Track

Once you approve the plan, run /spec implement. Your coding agent then works through the plan.md file, checking off tasks as it completes them.

Updated Artifacts:

.gemini/specs/tracks.md (Status updates)
.gemini/specs/tracks/<track_id>/plan.md (Status updates)
Project context files (Synchronized on completion)

/spec implement

SDD will:

Select the next pending task.
Follow the defined workflow (e.g., TDD: Write Test -> Fail -> Implement -> Pass).
Update the status in the plan as it progresses.
Verify Progress: Guide you through a manual verification step at the end of each phase to ensure everything works as expected.

During implementation, you can also:

Check status: Get a high-level overview of your project's progress.
```
/spec status
```
Revert work: Undo a feature or a specific task if needed.
```
/spec revert
```
Review work: Review completed work against guidelines and the plan.
```
/spec review
```

Commands Reference

Command	Description	Artifacts
`/spec setup`	Scaffolds the project and sets up the SDD environment. Run this once per project.	`.gemini/specs/product.md` `.gemini/specs/product-guidelines.md` `.gemini/specs/tech-stack.md` `.gemini/specs/workflow.md` `.gemini/specs/tracks.md`
`/spec create`	Starts a new feature or bug track. Generates `spec.md` and `plan.md`.	`.gemini/specs/tracks/<id>/spec.md` `.gemini/specs/tracks/<id>/plan.md` `.gemini/specs/tracks.md`
`/spec implement`	Executes the tasks defined in the current track's plan.	`.gemini/specs/tracks.md` `.gemini/specs/tracks/<id>/plan.md`
`/spec status`	Displays the current progress of the tracks file and active tracks.	Reads `.gemini/specs/tracks.md`
`/spec revert`	Reverts a track, phase, or task by analyzing git history.	Reverts git history
`/spec review`	Reviews completed work against guidelines and the plan.	Reads `plan.md`, `product-guidelines.md`

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