• The pyramid was an economics argument, not a quality law. Unit tests were cheap and fast, so teams wrote many. Integration tests were slow and brittle, so teams wrote few. The shape encoded the cost structure of a previous era.
• Agents collapsed the cost of writing tests at every level. When authoring labor is no longer the constraint, the argument that produced the pyramid no longer holds. The shape was downstream of a price that just went to zero.
• A unit test the agent wrote shares the agent's blind spot. When one author writes the code and the test, both inherit the same misunderstanding. The test passes and the bug ships. Same-author tests confirm, they do not challenge.
• The seam is the cheapest test that still tells the truth. Integration and contract tests pin the boundaries between components the agent wired together. Coverage of seams, not lines, is the metric that survives agentic authorship.

Read the argument: The Test Pyramid Was an Economic Argument