Add weighted random workflow steps and a random choice agent tool

api/openapi.yaml

@@ -1817,8 +1817,9 @@ components:
     WorkflowStep:
       type: object
       description: >
-        Exactly one of stage (with its model or agents, and prompt), order or parallel. A stage gets the outputs of
-        the stages that end the step before it: the last stage of an order, every branch's last stage of a parallel.
+        Exactly one of stage (with its model or agents, and prompt), order, parallel or random. A stage gets the outputs
+        of the stages that end the step before it: the last stage of an order, every branch's last stage of a parallel,
+        the last stage of the step a random picked.
       properties:
         stage: { type: string, x-go-type-skip-optional-pointer: true, description: "The stage's name, one line of 1 to 100 characters, unique within the workflow." }
         model: { type: string, x-go-type-skip-optional-pointer: true, description: "The stage agent's model, which also picks its vendor: gpt-* models run on Codex, gemini-* models on Antigravity, every other model on Claude Code. Required without agents, refused with them." }
@@ -1831,6 +1832,17 @@ components:
           type: array
           items: { $ref: "#/components/schemas/WorkflowStep" }
           description: Branches run at the same time, each getting the outputs of the step before the parallel.
+        random:
+          type: array
+          items: { $ref: "#/components/schemas/WorkflowStep" }
+          description: >
+            Steps of which one runs, picked at random when a run or review starts, each with its weight as the chance
+            of being picked. The run's definition holds the step it picked in place of the random.
+        weight:
+          type: number
+          format: double
+          x-go-type-skip-optional-pointer: true
+          description: "Its chance of being picked in the random it is directly in, from 0 to 1; the weights of a random's steps add up to 1, and a step without one has 0. Refused anywhere else."
         agents:
           type: array
           items: { $ref: "#/components/schemas/TeamMember" }