brokerd: slim RPC caps + `ib` client-id offset

Caps-sec tightening now that `brokerd` is trading-only: NO
`piker.data.*` (feed) mods are RPC-enabled in the (live,
credentialed) trading actor anymore.

Deats,
- drop `_data_mods` for a minimal `_brokerd_service_mods`
  (just `piker.brokers._daemon`); dedup-compose with the
  backend's set in `spawn_brokerd()`.
- `broker_init()` reads the backend's `_brokerd_mods`
  (fallback: `__enable_modules__` for flat backends).
- fail fast in `spawn_brokerd()` via `validate.get_eps()`
  when a backend offers NO live order-ctl eps (eg.
  `kucoin`, `deribit`) -> tells the caller to use
  paper-mode instead of booting a dead actor; analogous
  warning in `datad_init()` for datad-ep-less backends.
- offset `ib`'s default `client_id` per daemon-kind in
  `load_aio_clients()`: post-split BOTH `datad.ib` and
  `brokerd.ib` connect to the same gw/tws endpoint and the
  shared default (6116 + linear retry incrs) would collide
  and burn the full conn-timeout retry cycle; datad gets
  +16, ad-hoc (test/cli) actors +32.
- drop the import-cleanup leftovers (`exceptiongroup`,
  `_FeedsBus` type-only import) and the now-resolved
  "expose datad" TODO in `.cli`.

(this patch was generated in some part by [`claude-code`][claude-code-gh])
[claude-code-gh]: https://github.com/anthropics/claude-code

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Prompt-IO: ai/prompt-io/claude/20260610T171344Z_eee19de0_prompt_io.md

ai/prompt-io/claude/20260610T171344Z_eee19de0_prompt_io.md

@@ -0,0 +1,43 @@
+---
+model: claude-fable-5[1m]
+service: claude
+session: 32d15f9a-b2d3-4c26-bdc9-190219141a25
+timestamp: 2026-06-10T17:13:44Z
+git_ref: datad_service
+diff_cmd: git log -1 -p --follow -- ai/prompt-io/claude/20260610T171344Z_eee19de0_prompt_io.md
+scope: code
+substantive: true
+raw_file: 20260610T171344Z_eee19de0_prompt_io.raw.md
+---
+
+## Prompt
+
+Same session-initiating `brokerd`-split instruction (see
+`20260610T170859Z_75cefe10_prompt_io.md`); this is the
+approved plan's final "stage 4": caps-sec slimming of
+the (live, credentialed) trading actor + the `ib`
+dual-daemon `client_id` collision mitigation flagged in
+the plan's risk register.
+
+## Response summary
+
+`brokerd` loses ALL `piker.data.*` (feed) RPC mods;
+spawn fails fast for datad-only backends with a "use
+paper-mode" error; `ib`'s default api-gw `client_id`
+gets a per-daemon-kind offset so `datad.ib` +
+`brokerd.ib` don't collide on connect.
+
+## Files changed
+
+- `piker/brokers/_daemon.py` — `_data_mods` -> minimal
+  `_brokerd_service_mods`; `broker_init()` reads
+  `_brokerd_mods` (fallback `__enable_modules__`);
+  `spawn_brokerd()` fail-fast via `validate.get_eps()`
+- `piker/brokers/ib/api.py` — role-based `client_id`
+  offset in `load_aio_clients()`
+- `piker/cli/__init__.py` — resolved "expose datad"
+  TODO
+
+## Human edits
+
+None — committed as generated.

ai/prompt-io/claude/20260610T171344Z_eee19de0_prompt_io.raw.md

@@ -0,0 +1,41 @@
+---
+model: claude-fable-5[1m]
+service: claude
+timestamp: 2026-06-10T17:13:44Z
+git_ref: datad_service
+diff_cmd: git log -1 -p --follow -- ai/prompt-io/claude/20260610T171344Z_eee19de0_prompt_io.md
+---
+
+NOTE: diff-ref mode entry (code committed in the same
+commit as this log); backfilled from the live dev
+session transcript per the `/prompt-io` skill rules.
+
+> `git log -1 -p --follow -- piker/brokers/_daemon.py`
+
+Generated: the fail-fast originally landed in
+`broker_init()` but was relocated to `spawn_brokerd()`
+mid-implementation after realizing `piker ledger`
+calls `broker_init()` directly even for paper accounts
+on datad-only backends (would have crashed the cli);
+the service-spawn path is the correct enforcement
+seam. Error text:
+
+  Backend 'kucoin' offers NO `brokerd` (live
+  order-control) eps!? It is likely a datad-only
+  provider, use paper-mode for clearing instead.
+
+(verified live via a `trio.run()` unit check.)
+
+> `git log -1 -p --follow -- piker/brokers/ib/api.py`
+
+Generated: in `load_aio_clients()`, when `client_id`
+is the 6116 default: `datad`-named actors offset +16
+(disjoint from `brokerd`'s linear `client_id + i`
+retry range), other non-`brokerd` (ad-hoc test/cli)
+actors +32. Rationale from the plan's risk register:
+post-split BOTH per-broker daemons connect to the same
+TWS/gw endpoint; a shared default id collides and
+burns up to `connect_timeout * retries` (90s) in
+retry cycles.
+
+> `git log -1 -p --follow -- piker/cli/__init__.py`

piker/brokers/_daemon.py

@@ -25,10 +25,8 @@ from contextlib import (
 )
 from types import ModuleType
 from typing import (
-    TYPE_CHECKING,
     AsyncContextManager,
 )
-import exceptiongroup as eg
 
 import tractor
 import trio
@@ -40,27 +38,20 @@ from piker.log import (
 from . import _util
 from . import get_brokermod
 
-if TYPE_CHECKING:
-    from ..data import _FeedsBus
-
 log = get_logger(name=__name__)
 
-# `brokerd` enabled modules
-# TODO: move this def to the `.data` subpkg..
+# `brokerd`-actor-always-enabled mods.
 # NOTE: keeping this list as small as possible is part of our caps-sec
-# model and should be treated with utmost care!
-_data_mods: str = [
-    'piker.brokers.core',
-    'piker.brokers.data',
+# model and should be treated with utmost care! In particular NO
+# `piker.data.*` feed mods should be enabled in this (live,
+# credentialed) trading actor; all data-feed serving is the
+# domain of the `datad.<broker>` sibling daemon, see
+# `piker.data._daemon._datad_service_mods`.
+_brokerd_service_mods: list[str] = [
     'piker.brokers._daemon',
-    'piker.data',
-    'piker.data.feed',
-    'piker.data._sampling'
 ]
 
 
-# TODO: we should rename the daemon to datad prolly once we split up
-# broker vs. data tasks into separate actors?
 @tractor.context
 async def _setup_persistent_brokerd(
     ctx: tractor.Context,
@@ -119,8 +110,10 @@ def broker_init(
 
     This includes:
     - load the appropriate <brokername>.py pkg module,
-    - reads any declared `__enable_modules__: listr[str]` which will be
-      passed to `tractor.ActorNursery.start_actor(enabled_modules=<this>)`
+    - reads any declared `_brokerd_mods: list[str]` (falling
+      back to the full `__enable_modules__` set for
+      not-yet-split backends) which will be passed to
+      `tractor.ActorNursery.start_actor(enable_modules=)`
       at actor start time,
     - deliver a references to the daemon lifetime fixture, which
       for now is always the `_setup_persistent_brokerd()` context defined
@@ -155,8 +148,14 @@ def broker_init(
     ]
     for submodname in getattr(
         brokermod,
-        '__enable_modules__',
-        [],
+        '_brokerd_mods',
+        # fallback for (flat, less mature) backends which
+        # don't yet declare a daemon-kind mod split.
+        getattr(
+            brokermod,
+            '__enable_modules__',
+            [],
+        ),
     ):
         subpath: str = f'{modpath}.{submodname}'
         enabled.append(subpath)
@@ -184,6 +183,22 @@ async def spawn_brokerd(
         f'backend: {brokername!r}'
     )
 
+    # fail fast on (data-only) backends which don't offer
+    # ANY live order-control eps; the caller should instead
+    # be using paper-mode (and thus never spawning us)!
+    from ..data.validate import get_eps
+    brokerd_eps: dict = get_eps(
+        get_brokermod(brokername),
+        'brokerd',
+    )
+    if not brokerd_eps:
+        raise RuntimeError(
+            f'Backend {brokername!r} offers NO `brokerd` '
+            f'(live order-control) eps!?\n'
+            f'It is likely a datad-only provider, use '
+            f'paper-mode for clearing instead.\n'
+        )
+
     (
         brokermode,
         tractor_kwargs,
@@ -205,7 +220,11 @@ async def spawn_brokerd(
     dname: str = tractor_kwargs.pop('name')  # f'brokerd.{brokername}'
     portal = await Services.actor_n.start_actor(
         dname,
-        enable_modules=_data_mods + tractor_kwargs.pop('enable_modules'),
+        enable_modules=list(dict.fromkeys(
+            _brokerd_service_mods
+            +
+            tractor_kwargs.pop('enable_modules')
+        )),
         debug_mode=Services.debug_mode,
         **tractor_kwargs
     )

piker/brokers/ib/api.py

@@ -1340,6 +1340,21 @@ async def load_aio_clients(
     ib = None
     client = None
 
+    # XXX: post (brokerd vs. datad)-split BOTH per-broker
+    # daemons connect to the same API gw/tws endpoint(s); to
+    # avoid `clientId` collisions (and the long conn-timeout
+    # retry cycle they cause) we offset the data-daemon's
+    # default id-range to be disjoint from `brokerd.ib`'s
+    # (which also retries with `client_id + i` increments).
+    if client_id == 6116:  # the default from above
+        aname: str = tractor.current_actor().name
+        if 'datad' in aname:
+            client_id += 16
+        # ad-hoc (test/cli) actors get their own range to
+        # avoid clashing with any live daemon-tree's conns.
+        elif 'brokerd' not in aname:
+            client_id += 32
+
     # attempt to get connection info from config; if no .toml entry
     # exists, we try to load from a default localhost connection.
     localhost = '127.0.0.1'

piker/cli/__init__.py

@@ -250,7 +250,6 @@ def cli(
 
     # TODO: load endpoints from `conf::[network].pikerd`
     # - pikerd vs. regd, separate registry daemon?
-    # - expose datad vs. brokerd?
     # - bind emsd with certain perms on public iface?
     regaddrs: list[tuple[str, int]] = regaddr or [(
         _default_registry_host,