{"version":"2.1.261","anchor":"new-prompt-cache-break-diagnostics-msg0-shape-tracking","canonical_anchor":"new-prompt-cache-break-diagnostics-msg0-shape-tracking","heading":"New prompt-cache-break diagnostics: msg0 shape tracking","tier":"internal","area":"Prompt Caching","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.261\/e\/new-prompt-cache-break-diagnostics-msg0-shape-tracking","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.261","markdown":"### New prompt-cache-break diagnostics: msg0 shape tracking\n\nNew internal diagnostics track the first message's shape to diagnose cache breaks.\n\nPrompt-cache-break diagnostics now capture a structured shape of the first message per cache source, covering block kinds, lengths, hashes, named sections, and worker-tool counts. When a cache break is attributed to the first message, this shape is diffed against the previous call, adding `msg0Sections`, `msg0ChangedSections`, `msg0AddedSections`\/`RemovedSections`, and `msg0ChangedBlocks` to the break-diagnosis telemetry.\n\n- Area: Prompt Caching\n- Tier: Under the hood\n- Useful: 2\/5\n- Signal: 2\/5"}