Files
hao-ai-lab-FastVideo/v2/runtime/session.py
T
SolitaryThinker 4e331eb7ff [refactor] v2: use absolute imports (v2.*) everywhere instead of relative
Mechanical conversion of every relative import under v2/ to an absolute v2.* path
(from .x / ..x / ...x -> from v2.<pkg>.x) so imports are unambiguous, grep-able, and
stable when code is copied/moved between entrypoints (VideoGenerator, CLI, server).

Surgical prefix-only rewrite: only the 'from <dots><module>' prefix changed — import
names, parentheses, multi-line formatting, comments, and ordering are byte-for-byte
preserved (no collapsing, no reorder, no unrelated reformatting).

- 471 imports across 125 files; v2/tests/ was already absolute (untouched).
- Validated: all 125 files compile, every 'from v2.* import' target resolves to a real
  module/package, zero relative imports remain (full sweep), CPU mini suite green
  (202 passed, 2 skipped).
2026-07-04 17:15:34 +00:00

84 lines
4.3 KiB
Python

"""WorldModelSession — a long-lived interactive world-model rollout (design_v3 §16, §12, §15e).
The realtime/interactive plane, made concrete. A one-shot ``engine.run`` generates a clip and forgets;
a *session* continues the world: each ``.act(action)`` resumes the causal ``chunk_rollout`` loop from
the **persistent world state** carried on the ``Session`` (its ``kv_handle``), streams frames as chunks
complete, and honors **step-boundary cancellation**. This exercises the seams a one-shot path never
touches — cross-request persistent context, the ``CHUNK_ROLLOUT`` loop driven incrementally, the
``Stream`` frame channel, and ``CancelScope`` — using the exact runtime primitives the engine uses
(``RuntimeLoopContext`` + ``LoopRunner``), so interleaving two sessions is still parity-safe.
Cancellation is transactional: the persistent world state advances only on a *completed* act, so a
cancelled rollout leaves the session resumable from the last good frame.
"""
from __future__ import annotations
from typing import Any, Callable
from v2._enums import ExecutionProfile
from v2.loop.driver import LoopRunner
from v2.models.common import text_encode_node_fn
from v2.request import DiffusionParams, TaskType, make_request
from v2.request.requests import Session
from v2.request.streams import Stream
from v2.runtime.context import RuntimeLoopContext
class WorldModelSession:
def __init__(self, engine: Any, model_id: str, *, session_id: str = "world",
window: int = 2, loop_id: str = "chunk_rollout"):
self.engine = engine
self.model_id = model_id
self.window = window # how many prior chunks of world state to carry forward
self.loop_id = loop_id
self.session = Session(session_id=session_id)
self.stream = Stream(session_id)
self.session.streams["video"] = self.stream
self.world_context: list = [] # the persistent world chunks (the §16 cross-request KV)
self.session.kv_handle = self.world_context
self.step = 0
@property
def instance(self) -> Any:
if self.model_id not in self.engine._registry:
raise KeyError(f"no model {self.model_id!r} registered on engine")
return self.engine._registry[self.model_id][0]
def act(self, action: str, *, seed: int | None = None,
step_hook: Callable[["WorldModelSession", int], None] | None = None) -> Any:
"""Advance the world by one action, continuing from persistent context; stream frames.
Raises ``request.Cancelled`` if cancelled at a step boundary — and because the world state is
only committed after the loop completes, a cancelled act leaves the session resumable."""
inst = self.instance
req = make_request(TaskType.V2W, self.model_id, action,
diffusion=DiffusionParams(seed=self.step if seed is None else seed))
slots: dict[str, Any] = {}
text_encode_node_fn(inst, slots, req, None)
slots["world_context"] = list(self.world_context) # thread the persistent state in
ctx = RuntimeLoopContext(
inst, observers=self.engine.observers, interceptors=self.engine.interceptors,
slots=slots, stream=self.stream, cancel_scope=self.session.cancel_scope,
profile=ExecutionProfile.SERVE, metrics={},
request_id=f"{self.session.session_id}.{self.step}")
runner = LoopRunner(inst.loop(self.loop_id), ctx, req, inst)
n = 0
while not runner.done:
if step_hook is not None:
step_hook(self, n) # test seam: may call self.cancel() at a boundary
runner.step() # peek() raises request.Cancelled if cancelled
n += 1
result = runner.result
new_chunks = list(result.outputs.get("chunks") or [])
self.world_context = (self.world_context + new_chunks)[-self.window:] # slide window; commit
self.session.kv_handle = self.world_context
self.step += 1
return result
def frames(self) -> list:
"""All streamed media chunks so far across the session (the realtime frame channel)."""
return [e for e in self.stream.events if e.type == "media.chunk"]
def cancel(self) -> None:
self.session.cancel_scope.cancel()