Ultracode becomes an on/off toggle that works at any effort level

What

Ultracode, which runs dynamic workflows (Claude orchestrating extra work) on every task, used to be one of the effort levels, shown as "xhigh + workflows". It is now a separate on/off switch for the session that you combine with any effort level.

• The /effort picker has a separate row reading Ultracode: on or off with "select to turn it" on or off and "dynamic workflows on every task". Selecting it sends ultracode on or ultracode off.
• The row only appears when workflows are available and the model supports xhigh effort. Workflow availability comes from the tengu_workflows_enabled gate unless CLAUDE_CODE_WORKFLOWS or the disableWorkflows / enableWorkflows settings override it.
• /effort usage now reads auto|ultracode [on|off], with a section headed "Ultracode (any effort level, this session only):".
• Cycling effort levels left and right no longer includes ultracode, and a current ultracode value is no longer mapped to max or high.
• A new session-only ultracode setting is described as "standing dynamic-workflow orchestration at any effort level".
• The status label shows the real effort level and adds " · ultracode" when it is on.
• The per-model supportsUltra field was dropped.
• SDK session state and get_settings report ultracodeRequested and ultracodeAvailable next to ultracode (applied.ultracode). ultracodeAvailable is true when dynamic workflows are enabled and the model supports it; hosts should only offer an Ultracode control while it is true. The ultracode description no longer says it implies xhigh effort.
• The check that the live model's effort still matches the recorded level no longer passes the ultracode setting.
• Skipping the limit on concurrent subagents (helper agents Claude starts) now only happens when ultracode is on and the model supports it, rather than depending on the effort level. The separate tengu_amber_kestrel bypass is unchanged. The limit itself is still set with CLAUDE_CODE_MAX_CONCURRENT_SUBAGENTS.

Why

If you used ultracode before, it now behaves differently: you pick your effort level and turn ultracode on or off on top of it. Sessions at a high effort level without ultracode may now hit the subagent limit where they did not before, and SDK hosts can tell "requested but unavailable" apart from "on".