ctx.tools.register(definition, { when }) adds a synchronous or asynchronous
condition. AgentLoop resolves conditions once per proposed step with the
agent, the model selection that step preparation captured, and the turn
signal, before prompt assembly and agent/pre-step. The resulting
ResolvedToolSet governs tool declarations, Native dispatch, PTC bindings,
and nested calls for that step and its retries, and the turn disposes it
when the proposal is rejected or fails, when no step opens, and after the
step. A false condition removes the tool everywhere; a thrown condition
ends the turn with TOOL_ACTIVATION_FAILED. Calls whose registration was
replaced or removed during the step return UNKNOWN_TOOL.
system-prompt/assemble now transforms PromptPresentation without a tool
array, so tool declarations stay provider-owned. exit_plan_mode is declared
only for steps whose selected plan state is active, the same state that
renders plan guidance; it still rejects a call before the selection is
logged.
Model selection stays as master defines it; this change adds no model
selection event or Agent field.
Log tool changes as developer messages independently of model capability,
fold committed headers and updates into Session.toolHistory(), and let the
LLM runtime construct deferred and retained declarations for routes that
declare a toolUpdate mode. DeepSeek serializes updates as system-role
tool_addition/tool_removal blocks with defer_loading and the tool-changes
beta header. An unchanged restored tool continues the series and is
re-offered through its recorded blocks instead of rewriting declarations.
Replace the obsolete rejection tests with wire assertions and add coverage
for the session fold, loop emission, route projection, config validation,
and the beta header. Chat and Trajectory changes land separately.
Yichen Jiang