Summary

You now know that Cogitave answers "which database, which infrastructure, which model" the same way every time: a stated default, a real decision tree, and a deviation rule gated on a measured need and an ADR - never per-team taste, and never guessed from memory.

In this module, you:

• Learned the three-layer guidance model from ADR-0021: selection guides say which family for which workload, the technology radar says what is adopted, and the domain standards say how to build with the choice.
• Learned the shared shape every decision guide follows - a default, a walkable decision tree, a machine-readable matrix an agent can query, and a deviation rule that requires a measured ceiling recorded in an ADR (or, for model selection, an eval).
• Walked the database selection tree to Cogitave Core's query layer for a full-text search need, the infrastructure selection tree to a container on managed Kubernetes for a long-running service, and the model selection posture to the most capable tier for a new, correctness-critical task.
• Learned that landing on the default needs nothing recorded; only leaving it does, and you now know exactly what that record must state.

That completes the four modules of the "Patterns and golden paths" path: reuse-first engineering, navigating the patterns catalog, inheriting the project baseline, and now using the decision guides to make a justified technology choice.

Next steps

• Patterns and golden paths - return to the path to claim your trophy.
• ADR-0021 - re-read the full decision that governs all three guides.
• Model selection - revisit the cost levers and the eval-gated routing rule before your next production model choice.