{"version":"2.1.221","anchor":"background-attach-telemetry-gets-cold-start-and-surface-dime","canonical_anchor":"background-attach-telemetry-gets-cold-start-and-surface-dime","heading":"Background attach telemetry gets cold-start and surface dimensions","tier":"internal","area":"Telemetry","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221\/e\/background-attach-telemetry-gets-cold-start-and-surface-dime","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221","markdown":"### Background attach telemetry gets cold-start and surface dimensions\n\nBackground attach events now record cold starts, surface and first frame details.\n\n**What**\n\nThe `tengu_bg_attach_outcome` event carries considerably more detail about how an attach happened.\n\n**Details**\n\n- New attributes: `attach_cold`, `daemon_booted`, `first_frame_kind`, `surface`, a validated `via`, plus message-count fields.\n- Those attribute names were added to the low-cardinality attribute allowlist.\n- `via` is now filtered against a fixed set (starting, running, resuming and so on) rather than passed through as-is.\n\n**Evidence**\n\n`first_frame_kind`\n\n- Area: Telemetry\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 0\/5"}