[aikins01]

Several pages fell behind the product changes merged in telemetry-dev/telemetry.dev since mid-October, and a few described behavior that no longer matches. All of the changes described here are deployed.

• Cost by token class (telemetry-dev/telemetry.dev#648, telemetry-dev/telemetry.dev#666). A new section on the Cost calculation page says how the server splits a calculated cost into input, cache read, cache write, reasoning, and output, which spans have no split, and how the worked example splits. The Traces page says where the span panel shows it, and the MCP page lists the five get_trace fields.
• Trace and session pages (telemetry-dev/telemetry.dev#622, telemetry-dev/telemetry.dev#637, telemetry-dev/telemetry.dev#655, telemetry-dev/telemetry.dev#675). The span panel now shows the span ID, the time split of an agent span, event levels, and a Truncated at source badge, and it loads values of up to 2,000,000 characters. Enter and Space open a span from the tree. The Not captured text links to privacy settings. The session page reads 4,000-character previews of prompts and replies. The log details said they show the full message; they show the first 1,000 characters.
• Lists and links (telemetry-dev/telemetry.dev#616, telemetry-dev/telemetry.dev#625, telemetry-dev/telemetry.dev#655). The traces lists take the traces that started in the range. Overview model and provider rows open the spans list with the Operation: model calls chip and the Overview's range. Sessions are listed by the start of their latest trace.
• MCP errors (telemetry-dev/telemetry.dev#572, telemetry-dev/telemetry.dev#607). The MCP page lists the error codes in _meta and says that unknown arguments are refused.
• Accept telemetry (telemetry-dev/telemetry.dev#569, telemetry-dev/telemetry.dev#595). The Projects page gets a section on turning it off, and the OTLP error table gets the 403 project_not_accepting_telemetry row it was missing.
• Evals and prompts (telemetry-dev/telemetry.dev#570, telemetry-dev/telemetry.dev#580, telemetry-dev/telemetry.dev#628). The experiment action example used @main; it now uses the experiment-action-v1 tag, as the product page does. The Evals API says that text with U+0000 or a lone surrogate gets 400 invalid_request. The Prompts page says that a label cannot point to a version with a broken include, that moving or removing a label ends its rollout, that a rollout does not reach prompts that include this one, and when a label removal is refused.

Two merged SDK changes are not released yet, so the SDK and action text still describes the released versions: sending each value whole with the 16 MiB record cut and the 64 MiB queue budget (telemetry-dev/telemetry#148, in @telemetry-dev/sdk 0.2.3 and telemetry-dev 0.3.3), and the experiment action fixes (telemetry-dev/telemetry#154 and telemetry-dev/telemetry#157, in experiment-action 1.0.1). Those pages need an update once the release PR telemetry-dev/telemetry#146 merges.

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	telemetry-docs	798350e	Commit Preview URL Branch Preview URL	Oct 31 2026, 05:49 PM