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 ·

New telemetry: prefix-break diagnostics with sampled hashing

New sampled telemetry records detailed hashes around cache-prefix breaks.

TierUnder the hoodhow much it should matter to you
Useful1my rating, 1 to 5
Signal1worth watching, 1 to 5
AreaPrompt Cachingwhat it touches
KindInternal Changesin v2.1.261,
Under the hood No documentation found

New sampled telemetry records detailed hashes around cache-prefix breaks.

A new tengu_prefix_break_hashes telemetry event records detailed per-message-block hashes and diffs (types, roles, folded attachment info) around a cache-prefix break. It's gated by a sampling rate read from remote config, limited to first-party API usage, and excluded for HIPAA accounts.

Read from
Names in the bundletengu_prefix_break_hashes
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 →