release aidev BREAKING SIG 4/5

Pi: session-affinity config breaking change, dynamic tool loading, Fable 5 xhigh/max

Removes the openai-responses sendSessionIdHeader flag — replace sendSessionIdHeader: false with sessionAffinityFormat: "openai-nosession" (breaking). Adds cache-friendly dynamic tool loading, a Ctrl+X copy shortcut, native xhigh/max thinking for Claude Fable 5, and toolChoice support.

PUBLISHED2026-07-14
OBSERVED2026-08-21
AGE1mo
SOURCES1

Breaking

  • Removed compat.sendSessionIdHeader from models.json; session affinity now set via compat.sessionAffinityFormat ("openai", "openai-nosession", or "openrouter") — migrate sendSessionIdHeader: false to sessionAffinityFormat: "openai-nosession" (#6496)

New features

  • Extensions can add tools during execution while supported Anthropic and OpenAI Responses models preserve prompt-cache prefixes
  • Ctrl+X copies the last assistant message, or selected message in /tree
  • Inherited native xhigh and max thinking levels for Claude Fable 5 across generated provider catalogs (#6490)
  • Inherited toolChoice support for OpenAI and Codex Responses, including required and named tool selection (#6588)

Fixes

  • Inherited OpenRouter context windows now use top provider's actual context length (#6481)
  • OpenRouter OpenAI-compatible session IDs now use x-session-id header (#6496)
  • /login amazon-bedrock now prompts for and saves an API key; ambient AWS creds keep SigV4 (#6532)
  • Cloudflare Workers AI / AI Gateway auth uses ambient account and gateway IDs (#6292)
  • Legacy terminal decoding for Alt+,/Alt+. fixed (#6523)
  • GitHub Copilot mai-code-1-flash-picker routes via /responses (#6544)
  • Branch summaries work with ambient-auth providers (#6595); Bedrock surfaces unhandled stop reasons (#6598)
  • System prompt cache invalidation fixed by dropping the date from the default prompt (#6621)
breakingfeatureapi-changefixmodel-support

COMMUNITY

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