Subagents

Opus decides. Sonnet and Haiku do the legwork.

Main thread Opus designs, decides, debugs repo-scoutHaiku find every place X appears schema-ladder-scoutHaiku inventory the database migrations ai-docs-auditorSonnet docs that drifted from the code security-reviewerSonnet secrets, PII, unsafe paths
Each spawn gets a short brief and a named model. What comes back is findings, not file dumps, so the main thread's context stays clean.
HaikuMechanical work with one right answer: searches, counts, inventories.
SonnetBounded reasoning against a clear spec: audits, reviews, code for a settled design.
Opus: never a subagentArchitecture and debugging stay on the main thread, where the context is.