Copy timestamps from source to FSP dest buffer

Slice up to history's length worth of (latest) time stamps from source
series read at the start of the history init phase.

piker/fsp/_engine.py

@@ -112,8 +112,9 @@ async def fsp_compute(
         flume.rt_shm,
     )
 
-    # Conduct a single iteration of fsp with historical bars input
-    # and get historical output
+    # HISTORY COMPUTE PHASE
+    # conduct a single iteration of fsp with historical bars input
+    # and get historical output, pack into 
     history_output: Union[
         dict[str, np.ndarray],  # multi-output case
         np.ndarray,  # single output case
@@ -130,7 +131,8 @@ async def fsp_compute(
     # each respective field.
     fields = getattr(dst.array.dtype, 'fields', None).copy()
     fields.pop('index')
-    history: Optional[np.ndarray] = None  # TODO: nptyping here!
+    history_by_field: Optional[np.ndarray] = None
+    src_time = src.array['time']
 
     if (
         fields and
@@ -146,7 +148,7 @@ async def fsp_compute(
             if key in history_output:
                 output = history_output[key]
 
-                if history is None:
+                if history_by_field is None:
 
                     if output is None:
                         length = len(src.array)
@@ -156,7 +158,7 @@ async def fsp_compute(
                     # using the first output, determine
                     # the length of the struct-array that
                     # will be pushed to shm.
-                    history = np.zeros(
+                    history_by_field = np.zeros(
                         length,
                         dtype=dst.array.dtype
                     )
@@ -164,7 +166,7 @@ async def fsp_compute(
                 if output is None:
                     continue
 
-                history[key] = output
+                history_by_field[key] = output
 
     # single-key output stream
     else:
@@ -173,11 +175,13 @@ async def fsp_compute(
                 f'`{func_name}` is a single output FSP and should yield an '
                 '`np.ndarray` for history'
             )
-        history = np.zeros(
+        history_by_field = np.zeros(
             len(history_output),
             dtype=dst.array.dtype
         )
-        history[func_name] = history_output
+        history_by_field[func_name] = history_output
+
+    history_by_field['time'] = src_time[-len(history_by_field):]
 
     # TODO: XXX:
     # THERE'S A BIG BUG HERE WITH THE `index` field since we're
@@ -194,7 +198,10 @@ async def fsp_compute(
 
     # TODO: can we use this `start` flag instead of the manual
     # setting above?
-    index = dst.push(history, start=first)
+    index = dst.push(
+        history_by_field,
+        start=first,
+    )
 
     profiler(f'{func_name} pushed history')
     profiler.finish()

piker/fsp/_volume.py

@@ -268,8 +268,7 @@ async def flow_rates(
         'dark_dvlm_rate': None,
     }
 
-    # TODO: 3.10 do ``anext()``
-    quote = await source.__anext__()
+    quote = await anext(source)
 
     # ltr = 0
     # lvr = 0