diff --git a/piker/fsp/_engine.py b/piker/fsp/_engine.py
index aafaf76c..dac672bb 100644
--- a/piker/fsp/_engine.py
+++ b/piker/fsp/_engine.py
@@ -1,5 +1,5 @@
 # piker: trading gear for hackers
-# Copyright (C) Tyler Goodlet (in stewardship of piker0)
+# Copyright (C) Tyler Goodlet (in stewardship of pikers)
 
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License as published by
@@ -27,29 +27,19 @@ import pyqtgraph as pg
 import trio
 from trio_typing import TaskStatus
 import tractor
+from tractor._portal import NamespacePath
 
 from ..log import get_logger, get_console_log
 from .. import data
 from ..data import attach_shm_array
 from ..data.feed import Feed
 from ..data._sharedmem import ShmArray
-from ._momo import _rsi, _wma
-from ._volume import _tina_vwap, dolla_vlm
+# from ._momo import _rsi, _wma
+# from ._volume import _tina_vwap, dolla_vlm
+from ._api import _load_builtins
 
 log = get_logger(__name__)
 
-_fsp_builtins = {
-    'rsi': _rsi,
-    'wma': _wma,
-    'vwap': _tina_vwap,
-    'dolla_vlm': dolla_vlm,
-}
-
-# TODO: things to figure the heck out:
-# - how to handle non-plottable values (pyqtgraph has facility for this
-#   now in `arrayToQPath()`)
-# - composition of fsps / implicit chaining syntax (we need an issue)
-
 
 @dataclass
 class TaskTracker:
@@ -88,7 +78,7 @@ async def fsp_compute(
     src: ShmArray,
     dst: ShmArray,
 
-    func_name: str,
+    # func_name: str,
     func: Callable,
 
     attach_stream: bool = False,
@@ -115,15 +105,27 @@ async def fsp_compute(
     # and get historical output
     history_output = await out_stream.__anext__()
 
+    func_name = func.__name__
     profiler(f'{func_name} generated history')
 
-    # build a struct array which includes an 'index' field to push
-    # as history
+    # build struct array with an 'index' field to push as history
     history = np.array(
         np.arange(len(history_output)),
         dtype=dst.array.dtype
     )
-    history[func_name] = history_output
+
+    # TODO: push using a[['f0', 'f1', .., 'fn']] = .. syntax no?
+    # if the output array is multi-field then push
+    # each respective field.
+    fields = getattr(history.dtype, 'fields', None)
+    if fields:
+        for key in fields.keys():
+            if key in history.dtype.fields:
+                history[func_name] = history_output
+
+    # single-key output stream
+    else:
+        history[func_name] = history_output
 
     # TODO: XXX:
     # THERE'S A BIG BUG HERE WITH THE `index` field since we're
@@ -164,8 +166,9 @@ async def fsp_compute(
                 async for processed in out_stream:
 
                     log.debug(f"{func_name}: {processed}")
+                    key, output = processed
                     index = src.index
-                    dst.array[-1][func_name] = processed
+                    dst.array[-1][key] = output
 
                     # NOTE: for now we aren't streaming this to the consumer
                     # stream latest array index entry which basically just acts
@@ -194,7 +197,7 @@ async def cascade(
     src_shm_token: dict,
     dst_shm_token: tuple[str, np.dtype],
 
-    func_name: str,
+    ns_path: NamespacePath,
 
     zero_on_step: bool = False,
     loglevel: Optional[str] = None,
@@ -213,10 +216,14 @@ async def cascade(
     src = attach_shm_array(token=src_shm_token)
     dst = attach_shm_array(readonly=False, token=dst_shm_token)
 
-    func: Callable = _fsp_builtins.get(func_name)
+    # func: Callable = _fsp_builtins.get(tuple(ns_path))
+    func: Fsp = _load_builtins().get(
+        NamespacePath(ns_path)
+    )
+
     if not func:
         # TODO: assume it's a func target path
-        raise ValueError('Unknown fsp target: {func_name}')
+        raise ValueError(f'Unknown fsp target: {ns_path}')
 
     # open a data feed stream with requested broker
     async with data.feed.maybe_open_feed(
@@ -231,11 +238,12 @@ async def cascade(
 
     ) as (feed, quote_stream):
 
-        profiler(f'{func_name}: feed up')
+        profiler(f'{func}: feed up')
 
         assert src.token == feed.shm.token
         # last_len = new_len = len(src.array)
 
+        func_name = func.__name__
         async with (
             trio.open_nursery() as n,
         ):
@@ -252,7 +260,7 @@ async def cascade(
                 src=src,
                 dst=dst,
 
-                func_name=func_name,
+                # func_name=func_name,
                 func=func
             )
 
diff --git a/piker/ui/_fsp.py b/piker/ui/_fsp.py
index 22196f23..97dd5022 100644
--- a/piker/ui/_fsp.py
+++ b/piker/ui/_fsp.py
@@ -29,6 +29,7 @@ import numpy as np
 from pydantic import create_model
 import tractor
 # from tractor.trionics import gather_contexts
+from tractor._portal import NamespacePath
 import pyqtgraph as pg
 import trio
 from trio_typing import TaskStatus
@@ -38,57 +39,25 @@ from .._cacheables import maybe_open_context
 from ..calc import humanize
 from ..data._sharedmem import (
     ShmArray,
-    maybe_open_shm_array,
     try_read,
 )
 from ._chart import (
     ChartPlotWidget,
     LinkedSplits,
 )
-from .. import fsp
 from ._forms import (
     FieldsForm,
     mk_form,
     open_form_input_handling,
 )
+from ..fsp._api import maybe_mk_fsp_shm, Fsp
+from ..fsp import cascade
+from ..fsp._volume import tina_vwap, dolla_vlm
 from ..log import get_logger
 
 log = get_logger(__name__)
 
 
-def maybe_mk_fsp_shm(
-    sym: str,
-    field_name: str,
-    display_name: Optional[str] = None,
-    readonly: bool = True,
-
-) -> (ShmArray, bool):
-    '''
-    Allocate a single row shm array for an symbol-fsp pair if none
-    exists, otherwise load the shm already existing for that token.
-
-    '''
-    uid = tractor.current_actor().uid
-    if not display_name:
-        display_name = field_name
-
-    # TODO: load function here and introspect
-    # return stream type(s)
-
-    # TODO: should `index` be a required internal field?
-    fsp_dtype = np.dtype([('index', int), (field_name, float)])
-
-    key = f'{sym}.fsp.{display_name}.{".".join(uid)}'
-
-    shm, opened = maybe_open_shm_array(
-        key,
-        # TODO: create entry for each time frame
-        dtype=fsp_dtype,
-        readonly=True,
-    )
-    return shm, opened
-
-
 def has_vlm(ohlcv: ShmArray) -> bool:
     # make sure that the instrument supports volume history
     # (sometimes this is not the case for some commodities and
@@ -148,11 +117,13 @@ async def open_fsp_sidepane(
     assert len(conf) == 1  # for now
 
     # add (single) selection widget
-    for display_name, config in conf.items():
-        schema[display_name] = {
+    for name, config in conf.items():
+        # schema[display_name] = {
+        # name = target.__name__
+        schema[name] = {
                 'label': '**fsp**:',
                 'type': 'select',
-                'default_value': [display_name],
+                'default_value': [name],
             }
 
         # add parameters for selection "options"
@@ -180,7 +151,7 @@ async def open_fsp_sidepane(
     # https://pydantic-docs.helpmanual.io/usage/models/#dynamic-model-creation
     FspConfig = create_model(
         'FspConfig',
-        name=display_name,
+        name=name,
         **params,
     )
     sidepane.model = FspConfig()
@@ -228,8 +199,9 @@ async def run_fsp_ui(
     linkedsplits: LinkedSplits,
     shm: ShmArray,
     started: trio.Event,
-    func_name: str,
-    display_name: str,
+    target: Fsp,
+    # func_name: str,
+    # display_name: str,
     conf: dict[str, dict],
     loglevel: str,
     # profiler: pg.debug.Profiler,
@@ -245,12 +217,14 @@ async def run_fsp_ui(
 
     '''
     # profiler(f'started UI task for fsp: {func_name}')
+    name = target.__name__
 
     async with (
         # side UI for parameters/controls
         open_fsp_sidepane(
             linkedsplits,
-            {display_name: conf},
+            {name: conf},
+            # {display_name: conf},
         ) as sidepane,
     ):
         await started.wait()
@@ -264,24 +238,29 @@ async def run_fsp_ui(
                 chart = linkedsplits.subplots[overlay_with]
 
             chart.draw_curve(
-                name=display_name,
+                # name=display_name,
+                name=name,
                 data=shm.array,
                 overlay=True,
                 color='default_light',
-                array_key=func_name,
+                # array_key=func_name,
+                array_key=name,
                 separate_axes=conf.get('separate_axes', False),
                 **conf.get('chart_kwargs', {})
             )
             # specially store ref to shm for lookup in display loop
-            chart._overlays[display_name] = shm
+            # chart._overlays[display_name] = shm
+            chart._overlays[name] = shm
 
         else:
             # create a new sub-chart widget for this fsp
             chart = linkedsplits.add_plot(
-                name=display_name,
+                name=name,
+                # name=display_name,
                 array=shm.array,
 
-                array_key=func_name,
+                # array_key=func_name,
+                array_key=name,
                 sidepane=sidepane,
 
                 # curve by default
@@ -299,7 +278,8 @@ async def run_fsp_ui(
             # should **not** be the same sub-chart widget
             assert chart.name != linkedsplits.chart.name
 
-        array_key = func_name
+        # array_key = func_name
+        array_key = name
 
         # profiler(f'fsp:{func_name} chart created')
 
@@ -307,7 +287,8 @@ async def run_fsp_ui(
         update_fsp_chart(
             chart,
             shm,
-            display_name,
+            name,
+            # display_name,
             array_key=array_key,
         )
 
@@ -410,7 +391,7 @@ class FspAdmin:
         started: trio.Event,
         dst_shm: ShmArray,
         conf: dict,
-        func_name: str,
+        target: Fsp,
         loglevel: str,
 
     ) -> None:
@@ -420,11 +401,12 @@ class FspAdmin:
 
         '''
         brokername, sym = self.linked.symbol.front_feed()
+        ns_path = NamespacePath.from_ref(target)
         async with (
             portal.open_context(
 
                 # chaining entrypoint
-                fsp.cascade,
+                cascade,
 
                 # data feed key
                 brokername=brokername,
@@ -435,7 +417,8 @@ class FspAdmin:
                 dst_shm_token=dst_shm.token,
 
                 # target
-                func_name=func_name,
+                ns_path=str(ns_path),
+                # func_name=func_name,
 
                 loglevel=loglevel,
                 zero_on_step=conf.get('zero_on_step', False),
@@ -444,8 +427,13 @@ class FspAdmin:
             ctx.open_stream() as stream,
         ):
             # register output data
-            self._registry[(brokername, sym, func_name)] = (
-                stream, dst_shm, complete)
+            self._registry[
+                (brokername, sym, ns_path)
+            ] = (
+                stream,
+                dst_shm,
+                complete
+            )
 
             started.set()
 
@@ -455,7 +443,8 @@ class FspAdmin:
     async def start_engine_task(
         self,
 
-        display_name: str,
+        target: Fsp,
+        # display_name: str,
         conf: dict[str, dict[str, Any]],
 
         worker_name: Optional[str] = None,
@@ -464,17 +453,21 @@ class FspAdmin:
     ) -> (ShmArray, trio.Event):
 
         # unpack FSP details from config dict
-        func_name = conf['func_name']
-
+        # func_name = conf['func_name']
+        # func_name = target.__name__
+        fqsn = self.linked.symbol.front_feed()
         # allocate an output shm array
         dst_shm, opened = maybe_mk_fsp_shm(
-            self.linked.symbol.front_feed(),
-            field_name=func_name,
-            display_name=display_name,
+            fqsn,
+            # field_name=func_name,
+            # display_name=display_name,
+            target=target,
             readonly=True,
         )
-        if not opened:
-            raise RuntimeError(f'Already started FSP {func_name}')
+        # if not opened:
+        #     raise RuntimeError(
+        #         f'Already started FSP `{fqsn}:{func_name}`'
+        #     )
 
         portal = self.cluster.get(worker_name) or self.rr_next_portal()
         complete = trio.Event()
@@ -487,7 +480,8 @@ class FspAdmin:
             started,
             dst_shm,
             conf,
-            func_name,
+            # func_name,
+            target,
             loglevel,
         )
 
@@ -495,16 +489,21 @@ class FspAdmin:
 
     async def open_fsp_chart(
         self,
-        display_name: str,
+
+        target: Fsp,
+        # display_name: str,
+
         conf: dict,  # yeah probably dumb..
         loglevel: str = 'error',
 
     ) -> (trio.Event, ChartPlotWidget):
 
-        func_name = conf['func_name']
+        # func_name = conf['func_name']
+        # func_name = target.__name__
 
         shm, started = await self.start_engine_task(
-            display_name,
+            target,
+            # display_name,
             conf,
             loglevel,
         )
@@ -517,8 +516,9 @@ class FspAdmin:
                 self.linked,
                 shm,
                 started,
-                func_name,
-                display_name,
+                # func_name,
+                # display_name,
+                target,
 
                 conf=conf,
                 loglevel=loglevel,
@@ -671,8 +671,9 @@ async def open_vlm_displays(
 
             # spawn and overlay $ vlm on the same subchart
             shm, started = await admin.start_engine_task(
-                'dolla_vlm',
-                # linked.symbol.front_feed(),  # data-feed symbol key
+                # 'dolla_vlm',
+                dolla_vlm,
+
                 {  # fsp engine conf
                     'func_name': 'dolla_vlm',
                     'zero_on_step': True,
@@ -759,15 +760,18 @@ async def open_vlm_displays(
                     axis.size_to_values()
 
         # built-in vlm fsps
-        for display_name, conf in {
-            'vwap': {
-                'func_name': 'vwap',
+        # for display_name, conf in {
+        for target, conf in {
+            # 'vwap': {
+            tina_vwap: {
+                # 'func_name': 'vwap',
                 'overlay': 'ohlc',  # overlays with OHLCV (main) chart
                 'anchor': 'session',
             },
         }.items():
             started = await admin.open_fsp_chart(
-                display_name,
+                # display_name,
+                target,
                 conf,
             )
 
@@ -822,20 +826,22 @@ async def start_fsp_displays(
         open_fsp_admin(linked, ohlcv) as admin,
     ):
         statuses = []
-        for display_name, conf in fsp_conf.items():
+        # for display_name, conf in fsp_conf.items():
+        for target, conf in fsp_conf.items():
             started = await admin.open_fsp_chart(
-                display_name,
+                # display_name,
+                target,
                 conf,
             )
             done = linked.window().status_bar.open_status(
-                f'loading fsp, {display_name}..',
+                f'loading fsp, {target}..',
                 group_key=group_status_key,
             )
             statuses.append((started, done))
 
         for fsp_loaded, status_cb in statuses:
             await fsp_loaded.wait()
-            profiler(f'attached to fsp portal: {display_name}')
+            profiler(f'attached to fsp portal: {target}')
             status_cb()
 
     # blocks on nursery until all fsp actors complete