Add "no vlm" indication to `FeedInit`

Stash it for now in the (now mutable by default) `.shm_write_opts` and
have the new `Flume._has_vlm: bool` (only set to false internally by
feed layer) which can be read via new public `.has_vlm()` predicate.
Move out the old `.ui/_fsp` helper logic to this flume method.

piker/data/feed.py

@@ -309,7 +309,7 @@ async def allocate_persistent_feed(
     init: FeedInit = validate_backend(
         mod,
         [symstr],
-        init_msgs,
+        init_msgs,  # NOTE: only 1 should be delivered for now..
     )
     mkt: MktPair = init.mkt_info
     fqme: str = mkt.fqme
@@ -355,6 +355,10 @@ async def allocate_persistent_feed(
         _hist_shm_token=hist_shm.token,
         izero_hist=izero_hist,
         izero_rt=izero_rt,
+
+        # NOTE: some instruments don't have this provided,
+        # eg. commodities and forex from ib.
+        _has_vlm=init.shm_write_opts['has_vlm'],
     )
 
     # for ambiguous names we simply register the

piker/data/flows.py

@@ -240,3 +240,23 @@ class Flume(Struct):
         )
         imx = times.shape[0] - 1
         return min(first, imx)
+
+    # only set by external msg or creator, never
+    # manually!
+    _has_vlm: bool = True
+
+    def has_vlm(self) -> bool:
+
+        if not self._has_vlm:
+            return False
+
+        # make sure that the instrument supports volume history
+        # (sometimes this is not the case for some commodities and
+        # derivatives)
+        vlm: np.ndarray = self.rt_shm.array['volume']
+        return not bool(
+            np.all(np.isin(vlm, -1))
+            or np.all(np.isnan(vlm))
+        )
+
+

piker/data/validate.py

@@ -25,6 +25,8 @@ from typing import (
     Any,
 )
 
+from msgspec import field
+
 from .types import Struct
 from ..accounting import (
     Asset,
@@ -52,8 +54,11 @@ class FeedInit(Struct, frozen=True):
 
     # NOTE: only field we use rn in ``.data.feed``
     # TODO: maybe make a SamplerConfig(Struct)?
-    shm_write_opts: dict[str, Any] = {}
+    shm_write_opts: dict[str, Any] = field(
-    # 'sum_tick_vlm': True
+        default_factory=lambda: {
+        'has_vlm': True,
+        'sum_tick_vlm': True,
+    })
 
 
 def validate_backend(

piker/ui/_display.py

@@ -62,7 +62,6 @@ from ._style import hcolor
 from ._fsp import (
     update_fsp_chart,
     start_fsp_displays,
-    has_vlm,
     open_vlm_displays,
 )
 from ._forms import (
@@ -1335,7 +1334,7 @@ async def display_symbol_data(
                 None | ChartPlotWidget
             ] = {}.fromkeys(feed.flumes)
             if (
-                has_vlm(ohlcv)
+                flume.has_vlm()
                 and vlm_chart is None
             ):
                 vlm_chart = vlm_charts[fqme] = await ln.start(

piker/ui/_fsp.py

@@ -72,14 +72,6 @@ from .._profile import Profiler
 log = get_logger(__name__)
 
 
-def has_vlm(ohlcv: ShmArray) -> bool:
-    # make sure that the instrument supports volume history
-    # (sometimes this is not the case for some commodities and
-    # derivatives)
-    vlm = ohlcv.array['volume']
-    return not bool(np.all(np.isin(vlm, -1)) or np.all(np.isnan(vlm)))
-
-
 def update_fsp_chart(
     viz,
     graphics_name: str,