Public drift ledger: contract changes the crawler observed, paged

Contract diffs listed by fingerprint (keyed hashes of public registry names under a published key; recomputable, not anonymous) - a contract-diff record, not a safety verdict. Schema mcpindex.drift.ledger/4. One section per request: events (tool contract changes), context_events (server instructions and prompt metadata) or fleet_events (publisher-wide changes, counted once). When ledger_schema is mcpindex.drift.ledger/3, events omits tools whose only change was part of a publisher-wide change; look those up with /api/v1/drift/any. events and context_events pages hold up to 1,000 rows, newest first; fleet_events pages are packed by size. With no parameters this returns page 0 of events. To read a whole section, request ?section=<name> and follow next_cursor until it is null. A cursor stays in the generation it was issued for, so every page of one walk comes from the same hourly publish; a superseded generation stays readable for at least an hour after the next publish, then its cursors answer 410. The /3 single-response dump is retired.