three claude code agents, one codebase, zero coordination on memory. agent one fixed a test. agent two refactored the module that test covered. agent three wrote docs for the original version. none of them knew the others existed, but all three read and wrote to the same context. the merge was silent and wrong. each agent's observations poisoned the next agent's reads. added per-agent write scopes the next day. sqlite table per agent, cross-agent reads go through an explicit merge step. zero conflicts since.