𝐁𝐌𝐀𝐃 𝐯𝐬 𝐒𝐩𝐞𝐜 𝐊𝐢𝐭 𝐯𝐬 𝐊𝐢𝐫𝐨 𝐯𝐬 𝐒𝐮𝐩𝐞𝐫𝐩𝐨𝐰𝐞𝐫𝐬: 𝐖𝐡𝐚𝐭 𝐀𝐜𝐭𝐮𝐚𝐥𝐥𝐲 𝐓𝐫𝐚𝐧𝐬𝐟𝐞𝐫𝐬

Four spec-driven development frameworks with nothing in common on paper - two from the Scrum branch, one from Extreme Programming, one from AWS - converge on the same four structural mechanics. And they don't advertise why.

Most of what these frameworks sell you is ritual. The core - externalizing state to files, passing exact file paths instead of pointers, resetting context between steps, dispatching fresh subagents with no memory of prior conversation - transfers without the framework, installer, or vocabulary. Why? Because none of them invented it. An LLM's context window is not memory. That constraint forces the shape.

The convergence isn't a coincidence of good taste. It's a forced consequence of the medium.

I compared BMAD, GitHub's Spec Kit, Amazon's Kiro, and Superpowers by reading their full implementations. Different lineages, different vendors, different philosophies on PRDs and approval gates. Same four mechanics underneath. One productive disagreement on the fifth. Everything else is packaging.

𝐓𝐡𝐞 𝐫𝐞𝐚𝐥 𝐪𝐮𝐞𝐬𝐭𝐢𝐨𝐧: if frontier context windows grow large enough that externalizing state stops paying for itself, does this argument weaken? Yes. That's a falsifiability condition, not a hypothetical. A team that mistook ceremony for discipline abandoned a framework, burned two days on review gates built for six-month projects, and went back to unstructured prompting. They didn't lose spec-driven development. They lost the four mechanics tangled inside it.

Knowing which four mechanics matter and which are ritual is the difference between frameworks that stick and frameworks you discard.

Read the full analysis:

https://ranjankumar.in/spec-driven-development-invariants-not-frameworks

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