A Line of Documentation Was Acting as a Global Config Flag

I spent a morning hunting for a setting that did not exist. A while back I turned off Claude's co-authorship trailer in my commits — a deliberate choice at the time. Last week I decided I wanted it back. So I went looking for the switch I'd flipped. ~/.claude/settings.json : no key. settings.local.json : no key. ~/.claude.json , parsed as JSON, top-level plus all 38 project entries : no key. The 27 .claude/settings*.json files scattered across my two working drives: no key. Every CLAUDE.md and AGENTS.md I own: no mentions. Environment variables: nothing. A final sweep of my entire user directory — every *.json and *.md — returned three raw hits: a changelog and two copies of an editor extension's JSON schema. The note I wrote when that finished was two words: "Cero hits reales." Zero real hits. There was exactly one thing anywhere on disk that turned attribution off, and it was a sentence: ~/.claude/rules/ecc/common/git-workflow.md:12 Note: Attribution disabled globally via ~/.claude/settings.json. It had a Chinese twin, same file path with zh/ instead of common/ , same line 12. Both files are rules files. Rules files get loaded into every session. So every session opened with a line of documentation asserting, flatly and falsely, that a global setting was off — and the model behaved accordingly. The switch I remembered flipping never existed as a switch. The prose was the switch. The key that sentence gestured at, includeCoAuthoredBy , is deprecated and replaced by attribution . Neither is present in any of my configs, which means the default was active the whole time. The feature was on. Only the description of the world said otherwise, and the description won. The thesis Here's what I take from that, and from two more receipts this week: in an agent system, prose and constants are not documentation about the control plane. They are the control plane. I run a personal multi-agent system on top of Claude Code — 19 specialized agents, root-driven, single-writer, coo