Targets the three design_v3 claims that were most load-bearing AND least
exercised (sessions/realtime, training-plane boundary, the WorkUnit-generality
falsifier). All fit with no new runtime primitive (127 tests pass).
1. Interactive world-model session (runtime/session.py, §9.8) — the Session
plane had ZERO coverage. WorldModelSession drives the causal chunk_rollout
loop as a long-lived session: persistent cross-request world state on the
Session.kv_handle, frame streaming, transactional step-boundary cancellation
(a cancelled act leaves the world resumable), no cross-session smearing.
Added only a continuation seam to the chunk loop (init seeds context from a
world_context slot; default empty = unchanged one-shot path). 5 tests.
2. End-to-end RL over a cross-model workflow (training/methods/workflow_rl.py,
§9.9) — trains BOTH flux-t2i and wan-i2v from ONE final-video reward. Rolls
out the whole workflow with SDE capture in both instances; the same final
advantage drives FlowGRPO PPO on each stage's transformer; two WeightSyncPlans
on two instances. The earlier model (T2I) is trained by a reward on the final
video — end-to-end credit across a model boundary — proven causal by a control
(constant reward => zero advantage => nothing moves). 4 tests.
3. Heterogeneous WorkUnit co-scheduling (models/tiled/, §9.10) — the §17
falsifier. VAETileLoop makes VAE decode a loop of VAE_TILE units; tiling is
exact (== one-shot, C0), and VAE_TILE + DIFFUSION_STEP pipelines interleave
bit-identically and co-run in one batch. Validates the mechanism; the
economic half (does it pay) stays a port-time measurement. 4 tests.
designv4 §9.8–§9.10 + falsifier/layout/closing updates (127 tests, 20 files).
Answers "what's the right way to name/register custom pipelines like T2I→I2V":
treat a Workflow like a card — a stable namespaced id in the same servable
namespace, declared dependencies, and a two-level registry. No new concepts;
mirrors how cards are registered (and vllm-omni's pipeline_registry).
- program/workflow.py: Workflow gains `requires` (the cards it composes, derived
from stages) and `validate(engine)` (fail-fast if a required card is absent,
P7). New WorkflowRegistry: declarative workflow_id -> builder catalog for
out-of-tree/ad hoc use.
- runtime/engine.py: `_workflows` registry + register_workflow (validates deps,
rejects id collision with a model_id) + serves(); engine.run routes a request
whose model_id is a workflow to workflow.run — addressable exactly like a model.
Single-model hot path untouched.
- runtime/async_engine.py + serving/server.py: serves() and /models include
workflows (discoverable as servables).
- models/__init__.py: declarative `_WORKFLOWS` catalog (the cross-model analog of
_BUILDERS) + register_workflows() helper; build_image_video_engine now registers
the workflow too. Adding a custom pipeline = one catalog line.
- Naming convention: dotted/namespaced workflow_id (`image_video.t2i_i2v`),
distinct from kebab model ids, collision-checked. Renamed from `t2i_then_i2v`.
- tests (+5, 12 total in the file): addressable by id, requires/validate, id
collision, registry catalog, register_workflows helper. Full suite 114 passed.
- designv4 §9.6: the naming & registration convention documented.
Directory rename (git mv, history preserved) plus rewrite of all references: absolute imports in
tests, the zero-dep runner, docstrings, comments, and the README. No behavior change.
Run: python3 -m pytest v2/tests/ -q ; python3 v2/run_tests.py ; python3 -m v2.examples
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