---
model: claude-fable-5[1m]
service: claude
session: 32d15f9a-b2d3-4c26-bdc9-190219141a25
timestamp: 2026-06-10T17:11:42Z
git_ref: datad_service
diff_cmd: git log -1 -p --follow -- ai/prompt-io/claude/20260610T171142Z_119d2c04_prompt_io.md
scope: code
substantive: true
raw_file: 20260610T171142Z_119d2c04_prompt_io.raw.md
---

## Prompt

Same session-initiating `brokerd`-split instruction (see
`20260610T170859Z_75cefe10_prompt_io.md`); this is the
approved plan's "stage 1": introduce the `datad` daemon
machinery additively (nothing routes through it yet).
User-decided constraint applied: `datad.<broker>` is a
SIBLING of `brokerd.<broker>` under `pikerd`, spawned
via the existing `Services` + `maybe_spawn_daemon()`
machinery.

## Response summary

New `piker/data/_daemon.py` hosting the
`datad.<broker>` feed-only daemon-actor: lifetime
fixture owning the actor-global `_FeedsBus`, init/spawn
fns mirroring `.brokers._daemon` conventions and the
`samplerd` sub-daemon precedent, plus root-mod
registration, `piker.service` re-exports and a spawn
test.

## Files changed

- `piker/data/_daemon.py` — NEW:
  `_setup_persistent_datad()`, `datad_init()`,
  `spawn_datad()`, `maybe_spawn_datad()`,
  `_datad_service_mods`
- `piker/service/_actor_runtime.py` — add
  `piker.data._daemon` to `_root_modules`
- `piker/service/__init__.py` — re-export spawn eps
- `tests/test_services.py` — add `test_datad_spawn`

## Human edits

None — committed as generated.
