A failed boot went straight back to the model as "fix it", so it guessed: one draft raised its memory three rounds in a row while the real cause, an empty setting the server can't run without, stayed untouched. Now a failed boot is investigated first: - Evidence: the server's distinct error lines (timestamps and repeats removed), and a web search on the most telling one, with the top answer read through the reader. - Diagnosis: the model states the cause, the evidence for it, its confidence and the exact fix. If unsure, it asks for up to 3 checks: a search, a page, the files the server writes (a first boot of the draft), or a boot test with settings or the startup command changed. Results go back to it, two rounds at most. - Fix: the model applies exactly the diagnosed fix and nothing unrelated. - Attempt log: each cause, fix and outcome. A fix that changed nothing rules its cause out; if the diagnosis returns to a ruled-out cause, the build stops instead of guessing, and the PR lists what the builder found. Boot rounds go up to 5, since rounds now end on a ruled-out cause rather than a fixed count. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>