From issue trees to subagents — porting strategy craft into Claude Code.
The MECE issue tree was the canonical strategy artefact for fifty years. It turns out it maps almost perfectly onto a Claude Code sub‑agent graph. The decomposition discipline I learned at McKinsey is the single most valuable thing I brought into agentic engineering — and it transfers more cleanly than any code skill.
Draft in progress
What this essay will cover.
- The classical issue tree — root question, MECE branches, hypothesis at each leaf, evidence to test it. Why every McKinsey project really did start this way and why it works.
- The structural isomorphism — a Claude Code sub‑agent graph is the same artefact: root prompt, decomposed sub‑prompts, evidence (tool calls and outputs), recombination at the root. Same shape, different substrate.
- What transfers — MECE discipline, hypothesis‑first thinking, the rigour of the "so what?" test at each level, the partner habit of pruning a branch you've fallen in love with.
- What doesn't — the human apprenticeship around the tree (debating the branches with an EM, watching a partner reshape it in front of you) doesn't transfer; the model is not the EM, and pretending it is leads to lazy decomposition.
- The practical pattern I now use — a written root prompt, three to five sub‑agents, each with a specific evidence target, a synthesiser at the end. Looks remarkably like a McKinsey workplan.
- Why this is the most underrated career capital from a consulting background — the shape of how you decompose problems is the moat. AI fluency without decomposition discipline is just polished noise.
— Full essay coming. The thesis stands; the longer version walks through a concrete Frollie example.
— Lucas, November 2025