Can I get setup:upgrade to run automatically after di.xml changes?

Yes — PostToolUse hook scoped to Edit and Write. In .claude/settings.json: {"PostToolUse": [{"matcher": "Edit|Write", "hooks": [{"type": "command", "command": "if echo $CLAUDE_TOOL_INPUT | grep -qE 'di\\.xml|module\\.xml|db_schema'; then docker exec magento bin/magento setup:upgrade; fi"}]}]}. Two warnings: (a) setup:upgrade is slow (~30s on a fat install) — consider running setup:di:compile alone for di.xml-only edits; (b) the hook command runs synchronously and blocks the next tool call, so a session where you're rapid-firing edits will feel like syrup. Tune the matcher tight.