sgl-project/sglang · error · ValueError

invalid duration in action segment {segment!r}

Error message

invalid duration in action segment {segment!r}

What it means

Raised by parse_sana_wm_action_string when the frames part of a segment (after the last '-') is not all digits or is <= 0. Duration must be a positive integer.

Source

Thrown at python/sglang/multimodal_gen/runtime/pipelines_core/stages/model_specific_stages/sana_wm/base.py:133

            raise ValueError(f"{error_label} must be list[list[str]]")
        out.append([str(key).lower() for key in frame_actions])
    return out


def parse_sana_wm_action_string(action: str) -> list[list[str]]:
    cleaned = "".join(action.replace("，", ",").split())
    if not cleaned:
        raise ValueError("action string is empty")

    per_frame: list[list[str]] = []
    for segment in cleaned.split(","):
        if not segment or "-" not in segment:
            raise ValueError(
                f"invalid action segment {segment!r}; expected '<keys>-<frames>'"
            )
        keys_part, duration = segment.rsplit("-", 1)
        if not duration.isdigit() or int(duration) <= 0:
            raise ValueError(f"invalid duration in action segment {segment!r}")

        if keys_part.lower() == "none":
            keys: list[str] = []
        else:
            bad = sorted(
                {
                    char
                    for char in keys_part.lower()
                    if char not in _SANA_WM_ALLOWED_ACTION_KEYS
                }
            )
            if bad:
                raise ValueError(
                    f"unknown action keys {bad}; allowed keys are "
                    f"{sorted(_SANA_WM_ALLOWED_ACTION_KEYS)}"
                )
            keys = sorted(set(keys_part.lower()))
        # Fresh list per frame: repeated frames must NOT alias one list object

View on GitHub (pinned to 0132848349)

Solutions

1. Use a positive integer duration: 'ab-4' not 'ab-0' or 'ab-4.5'
2. Clamp/round durations upstream: f'{max(1, round(d))}'
3. Reject the request early with a clear message if duration parses to < 1

Example fix

// before
segment = 'ab-0'
// after
segment = 'ab-1'

assert all(p.isdigit() and int(p) > 0 for p in (seg.rsplit('-',1)[1] for seg in segments))

def durations_valid(s: str) -> bool:
    return all((lambda d: d.isdigit() and int(d) > 0)(seg.rsplit('-',1)[-1]) for seg in s.split(',') if seg)

When it happens

Trigger: Segments like 'ab-0', 'ab--1', 'ab-4.5', 'ab-x', or 'ab-' (empty duration). The code does segment.rsplit('-',1) then checks duration.isdigit() and int(duration) > 0.

Common situations: Zero or negative frame counts from user input; float durations like '4.5'; negative numbers creating '--1' after rsplit.

Related errors

• action string is empty
• invalid action segment {segment!r}; expected '<keys>-<frames
• unknown action keys {bad}; allowed keys are {sorted(_SANA_WM
• plucker_emb token count {plucker_emb.shape[1]} != latent tok
• chunk_size must be > 0, got {chunk_size}.

AI-assisted analysis of sgl-project/sglang@0132848349 (2026-08-28). Data as JSON: /api/errors/66a2b1726a59be10. Report an issue: GitHub.