The flow registers its long-handle author on the harness PDS, and a retry reuses that PDS: the account from the first attempt was still registered, so the retry failed on `Handle already taken` before it reached the browser. Derive the label from the clock, which stays inside the PDS's 18-character service-domain cap and still outgrows the chat column. Verified with `hack/e2e-web-local.sh chat-long-handle.spec.ts --repeat-each=2` against one harness: all four runs pass.