spec-kit (GitHub)

GitHub's open-source (MIT, Python) toolkit for spec-driven-development — treating specifications as executable blueprints that "directly generate working implementations," not static docs. The canonical SDD toolkit (already compared in spec-driven-ai-tools, now ingested as a primary source).

The workflow (six slash commands)

/speckit.constitution (project principles/governance) → /speckit.specify (requirements/user stories) → /speckit.clarify (resolve ambiguities) → /speckit.plan (technical strategy) → /speckit.tasks (ordered, actionable tasks) → /speckit.implement (execute). Plus GitHub-issue creation and quality validation. Describe what & why before how.

Integration & design

• Works with 30+ AI coding agents (Copilot, Claude Code, Gemini, Cursor, …) via either slash-command prompts or agent-native skills (agent-skills).
• Modular: extensions (new capabilities) + presets (workflow tweaks); tool-agnostic, so teams can enforce org standards across agents.

Why it belongs here

The reference implementation of spec-driven-development and a clean example of process-as- markdown delivered as cross-agent skills/commands — the authoring-time discipline that agentic-coding-harness products wrap around. Greenfield + brownfield + iterative use.

Enterprise extension model (2026-10-07, Microsoft for Developers)

A follow-up post (Apoorv Gupta, Principal SWE at Microsoft) answers how a large org adapts Spec Kit without forking it: "stable core with explicit extension points," in four composable layers.

• Presets — stackable, priority-ordered overrides of templates/commands/prompts/terminology (e.g. a security preset, a domain preset, layered over an org baseline).
• Extensions — new capabilities (commands, integrations, quality gates, scripts, hooks) — e.g. a security-review command, an accessibility gate, work-tracker integration.
• Bundles — versioned, installable packages of presets + extensions, with pinned versions and provenance tracking.
• Workflows — chained commands/prompts/scripts/human checkpoints, with conditional paths, loops, and pause/resume (bug remediation, release readiness, security review).

Also: a governed catalog split — an org catalog (vetted, highest priority) vs. a community catalog (discovery-only; listing "confirms format and metadata, not a security review or endorsement of its code") — and a layered constitution (org baseline → domain/tech overlay → team customization), composing the single /speckit.constitution this page already describes into three inheritance levels. Adoption is staged: baseline → presets → extensions → curated catalog → bundles → automate only well-understood processes.

No CLI syntax or code in the post — conceptual/architectural, first-party (Microsoft on a GitHub-owned tool). Read as the governance layer the original six-command workflow needed once an org, not a single repo, is the unit of adoption.

Related

spec-driven-development · spec-driven-ai-tools · agent-skills · agentic-coding-harness