Where this fits in the series: This article sits between Part 5 (the 75% wall — design around it, don't fix it) and Part 6 (the layered L0→L1→L2→L3 pipeline built from community feedback). It asks the upstream question: how does an agent loop know when to stop? The "demand red line vs. format red line" distinction below anticipates the L0 (evidence gate) vs. L1 (contract regex) split formalized in Part 6. The "no semantic-layer red line" claim is the same boundary later named the DPI bound.
The scope of this article is limited to tasks with objectively verifiable acceptance criteria (code, structured output, assertable results). For open-ended semantic tasks (writing copy, drafting analysis), the Red Line Principle does not apply.
Scope restated: The conclusions in this article hold only under the following conditions — the task has an objective verification standard, and that standard can be predefined by a human (code output matching expectations, schema validation passing, all tests green). For open-ended semantic tasks (writing copy, drafting analysis, generating creative content), no known automatic convergence signal exists within the scope of these experiments; refer to Rules 3 and 4. All data below is within this scope.
