Sweep 22 Sep 2026 · 15:52Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
Reading a new release v2.1.280 Building the pages · 4/6 1043 findings $36.88 so far
Claude Code v2.1.261 ·

Detailed prompt-cache-break diagnostics (message0 shape/section diffing) sampled off by default

Detailed prompt-cache-break diffing telemetry exists but is sampled at zero by default.

TierNothing to try yethow much it should matter to you
Useful3my rating, 1 to 5
Signal3worth watching, 1 to 5
AreaPrompt Cachingwhat it touches
KindIn Developmentin v2.1.261,
Nothing to try yet Notable No documentation found

Detailed prompt-cache-break diffing telemetry exists but is sampled at zero by default.

New telemetry can capture a detailed structural snapshot of the first request message, including block kinds, lengths, hashes, named sections like preamble, claudeMd, and workerToolsContext, and worker tool/MCP-server counts, diffing it on a cache break to report changed, added, and removed sections and blocks. This collection is sampled via the gate tengu_iridescent_gem, which defaults to a sample rate of 0, so none of this data is captured unless that rate is raised remotely.

Read from
Names in the bundletengu_iridescent_gem
How sure we are
One source agreesOne thing we can check says the same as this entry.
The name it cites is new in this buildNew in this build: tengu_iridescent_gem

See this entry in the whole of v2.1.261 →