{"version":"2.1.221","anchor":"much-richer-background-attach-timing-telemetry","canonical_anchor":"much-richer-background-attach-timing-telemetry","heading":"Much richer background-attach timing telemetry","tier":"internal","area":"Sessions","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221\/e\/much-richer-background-attach-timing-telemetry","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221","markdown":"### Much richer background-attach timing telemetry\n\nAttaching to a background session now records detailed timing, including a 30-second timeout flag.\n\n**What**\n\ntengu_bg_attach_outcome gains a large set of timing and content fields, purely observational.\n\n**Details**\n\n- New fields: attach_ms, content_paint_ms, prompt_idle_ms, timed_out, attach_censored, marks_expected, first_frame_kind (\"real\", \"dimhint\", \"unknown\"), surface, daemon_booted, attach_cold, msgs_loaded, msgs_in_jsonl and msgs_rendered_at_first_paint.\n- Measured from a caller-supplied t0, with a 30s watchdog that flags a timeout when no paint marks arrive.\n- The same fields are now attached to the connect-throw error path, failure_class `connect_throw`, and to detach and error results.\n- None of these field names exist in 2.1.220.\n\n**Evidence**\n\n`attach_censored`\n\n- Area: Sessions\n- Tier: Under the hood\n- Useful: 2\/5\n- Signal: 0\/5"}