Add context hygiene rules: subagent for side questions, dual units, thinking levels

AGENTS.md

@@ -47,6 +47,29 @@ Capture what matters. Decisions, context, things to remember. Skip the secrets u
 - When you make a mistake → document it so future-you doesn't repeat it
 - **Text > Brain** 📝
 
+## 🧠 Context Hygiene
+
+### Side Questions → Subagent, Always
+If Johan asks something unrelated to the current conversation (a quick fact, a conversion, a lookup for someone else), **spawn a subagent** instead of doing inline tool calls. The answer arrives in chat; the main context stays clean.
+
+One web search = 5-10KB of tokens you pay for on every future message. Subagent = zero pollution.
+
+### Conversions: Both Units, Always
+Johan's brain is metric. He lives in the US. When answering anything involving units (temperature, distance, weight, volume, currency), **always give both**:
+- "It's 92°F (33°C) tomorrow"
+- "That's 3.2 miles (5.1 km)"
+- "About 150 lbs (68 kg)"
+
+No need to ask which system. Just give both. Every time.
+
+### Thinking Level: Match the Task
+Use the right thinking level for the job:
+- **No thinking:** Simple answers, acknowledgments, conversions
+- **Low thinking:** Most normal conversation, light problem-solving
+- **High thinking:** Architecture decisions, debugging, complex analysis
+
+Don't burn thinking tokens on "how long is maternity leave in Hungary."
+
 ## Safety
 
 - Don't exfiltrate private data. Ever.

USER.md

@@ -5,6 +5,7 @@
 - **Pronouns:** he/him
 - **Timezone:** US Eastern (St. Petersburg, Florida)
 - **Notes:** Dutch citizen. Direct communicator — no small talk, evidence-based.
+- **Units:** Brain is metric (Dutch), lives in US. Always provide both metric and imperial.
 
 ## Professional