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Tools2026-09-04 · source-backed
2.1.260 adds a likely cause (changed tool definitions, changed system prompt, idled past TTL) to both /cost and the status line's prompt_cache field. The same release fixes prompt caching on Fable 5.1 not covering context attached after tool results, which meant that context was re-sent as uncached input on every tool-call turn, and stops /effort changes mid-session from invalidating the cache on Fable. For long agent sessions the Fable fix is the material one: tool-heavy turns were paying full input price for the attached context. Claude Code changelog
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The changelog through 2.1.235 (code.claude.com) confirms the todo-tool removal from Opus 4.8, Sonnet 5, Fable 5, and Mythos 5+ that ran here on 2026-08-15 is restorable with that flag. Everything else in this window has already been covered: the Bash memory cgroups and the tod...
Claude Code 2.1.229 shipped a config flag most people will scroll past: CLAUDE_CODE_WORKFLOW_PREFIX_STAGGER_MS. What it does is delay the launch of sibling agents that share a prompt prefix, so the second through Nth agents read the warm cache instead of each writing their own...
It now dedupes local CLAUDE.md files against checked-in ones, proposes trimming content it can derive from the codebase, ranks unused skills, MCP servers, and plugins by context cost, and flags slow hooks. Background subagents run by default and, when launched from claude agen...
Claude Code 2.1.233 added an environment variable configuring the WebFetch session URL cache TTL, with the default unchanged at 15 minutes (Claude Code Changelog). That default is a real problem for any agent polling a status page, a CI endpoint or a changelog inside a long se...
This one rearranged my week. An essay published August 4 walks through Databricks' independent benchmark of coding harnesses against its own multi-million-line codebase. Pi, a harness with four built-in tools and a system prompt under 1,000 tokens, paired with Opus 4.8 at xhig...
Three separate Anthropic changes over about two weeks point the same direction, and none of them announced themselves as a strategy. Claude Code 2.1.238 added claude self-hosted-runner --defer-shutdown-max-min, which keeps serving attached sessions on SIGTERM, parks whatever's...
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