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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial

Claude Code v2.1.223 ·

"Investigate first" system prompt experiment removed

Claude no longer spends up to a minute investigating before asking you a clarifying question.

You'll notice No documentation found Removed
JSON All of v2.1.223
You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
System PromptArea: what it touches
RemovedKind: in v2.1.223,
RemovedSection of the release
What

The experiment that told Claude to spend up to a minute on read-only investigation before asking a clarifying question has been taken out entirely.

Details
  • Gone: the CLAUDE_CODE_INVESTIGATE_FIRST environment variable, the tengu_slate_harrier gate, and its prompt-cache entry.
  • The shortened "compact" variant of the "Executing actions with care" block was removed too.
  • Only the full-length version of that block remains.
Evidence

# Executing actions with care

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Read from
Feature flag
tengu_slate_harrier Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.223: not a boolean we can read

These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.

Read once, for one account on one subscription tier, against v2.1.223. It isn't a statement about your account. What a flag value here can and cannot tell you

What has happened since
Flag reading moved The flag server now returns "off" for tengu_slate_harrier, read as this account. A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.
Flag reading moved The flag server now returns nothing at all, having stopped carrying it for tengu_slate_harrier, read as this account. A reading is one sample. Claude Code evaluates its flags remotely, so no client sees the targeting rule behind a value and this says nothing about your account.

See this across every release →

See this entry in the whole of v2.1.223 →

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