Source Intelligence
Follow Discord

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

← All of v2.1.91 Home All releases ←olderv2.1.90 v2.1.92newer→
Claude Code v2.1.91

Write Tool Append Mode [Gradual Rollout]

What

The Write tool gains a mode parameter with 'overwrite' (default) and 'append' options, allowing content to be added to the end of a file without rewriting it.

Status

Feature-flagged via tengu_maple_forge_w8k (default: false)

Details
  • New mode parameter on the Write tool schema
  • Description: "Use 'append' to add content to the end of an existing file instead of rewriting the full content — e.g. for logs, accumulating output, or adding entries"
  • Instruction: "Do NOT re-send the existing file contents" when appending
Evidence

Write append mode (gated by tengu_maple_forge_w8k, search for "mode:'append'")

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.91 →