diff --git a/ai/prompt-io/opencode/20261019T123725Z_eed58566_logger_compat_prompt_io.md b/ai/prompt-io/opencode/20261019T123725Z_eed58566_logger_compat_prompt_io.md
new file mode 100644
index 00000000..9d6f2b0f
--- /dev/null
+++ b/ai/prompt-io/opencode/20261019T123725Z_eed58566_logger_compat_prompt_io.md
@@ -0,0 +1,51 @@
+---
+created_at: 2026-10-19T12:37:25Z
+generated_by:
+  harness: opencode
+  provider: openai
+  model: openai/gpt-6.1-sol
+git_ref: eed58566
+scope: code
+substantive: true
+raw_file: 20261019T123725Z_eed58566_logger_compat_prompt_io.raw.md
+---
+
+## Prompt
+
+During the requested downstream/manual IB evaluation, the user reported
+immediate chart startup failure at the stale assertion
+`assert log.name == 'piker.service'` in maybe_spawn_daemon().
+The user then asked why continuing the post-mortem debugger ended with
+KeyboardInterrupt from the chart window's closeEvent().
+
+## Response summary
+
+Located the existing downstream logger compatibility commit
+c07e3cbde21807a4e193b3527ef8686a22cf4d96 and reproduced its code and
+existing regression tests in the evaluation worktree, unstaged.
+Preserved the earlier editable Tractor/dependency setup.
+Explained that closeEvent() sends SIGINT during chart teardown, adding
+a secondary KeyboardInterrupt after the original assertion unwinds.
+No window-close behaviour was modified.
+
+## Files changed
+
+- piker/log.py: exact package-prefix removal in both logger factories.
+- piker/service/_daemon.py: remove stale parent logger assertion.
+- piker/data/_daemon.py: retain setup, remove assertion-only local.
+- piker/brokers/_daemon.py: same broker startup compatibility fix.
+- piker/clearing/_ems.py: same EMS startup compatibility fix.
+- tests/test_logging.py: original four logger namespace regressions.
+
+## Verification
+
+- Logger regressions: four passed with --noconftest.
+- Normal pytest collection blocked by duplicate --ll registration.
+- Separate local TCP registrar smoke: pikerd/data daemon startup,
+  registration and teardown succeeded; no provider feed opened.
+- Imports resolve to this evaluation worktree and the evaluated
+  Tractor logging worktree.
+
+## Human edits
+
+None observed in this compatibility patch at capture time.
diff --git a/ai/prompt-io/opencode/20261019T123725Z_eed58566_logger_compat_prompt_io.raw.md b/ai/prompt-io/opencode/20261019T123725Z_eed58566_logger_compat_prompt_io.raw.md
new file mode 100644
index 00000000..3fdeeef1
--- /dev/null
+++ b/ai/prompt-io/opencode/20261019T123725Z_eed58566_logger_compat_prompt_io.raw.md
@@ -0,0 +1,46 @@
+---
+created_at: 2026-10-19T12:37:25Z
+generated_by:
+  harness: opencode
+  provider: openai
+  model: openai/gpt-6.1-sol
+git_ref: eed58566
+diff_cmd: git diff HEAD -- piker/log.py piker/service/_daemon.py piker/data/_daemon.py piker/brokers/_daemon.py piker/clearing/_ems.py
+---
+
+## Captured response
+
+Found it: downstream `c07e3cbd` (“Preserve exact `piker`
+logger namespaces”) removes this assertion and the equivalent
+ones in data, broker and EMS startup. It also fixes the logger
+prefix handling.
+
+That compatibility patch was present in our earlier evaluation
+stack but is absent from this base. I’ll apply its code and
+existing regression tests here as an unstaged patch.
+
+## Patch provenance
+
+The five production-file changes and tests/test_logging.py reproduce
+the code/test changes from c07e3cbde21807a4e193b3527ef8686a22cf4d96.
+This is a working-tree transplant, not a new commit or cherry-pick.
+The test file's Git blob is 437554461de44833940b24d77a565160fc3ac6e0,
+matching the original commit. piker/log.py matches that commit.
+
+## Verification output
+
+Logger tests with --noconftest: 4 passed in 0.36s.
+Normal pytest startup failed before collection because both Piker and
+modern Tractor register --ll. The logger tests use no project fixtures.
+An external disposable-registrar smoke script exercised open_pikerd(),
+maybe_spawn_datad('kraken'), registration and teardown successfully:
+Data daemon startup: OK
+
+## Follow-up response
+
+Yep—the traceback shows the window’s `closeEvent()` explicitly
+sending SIGINT to its own process, which raises `KeyboardInterrupt`.
+Continuing a post-mortem REPL lets the original assertion unwind;
+it doesn’t resume successful startup. The resulting window close
+then adds that KBI. It’s secondary shutdown behaviour, and it
+makes the original failure harder to read.
diff --git a/piker/brokers/_daemon.py b/piker/brokers/_daemon.py
index dafb3b81..8aa45f33 100644
--- a/piker/brokers/_daemon.py
+++ b/piker/brokers/_daemon.py
@@ -77,12 +77,11 @@ async def _setup_persistent_brokerd(
     # any further (level) configuration on their own B)
     actor: tractor.Actor = tractor.current_actor()
     tll: str = actor.loglevel
-    log = get_console_log(
+    get_console_log(
         level=loglevel or tll,
         name=f'{_util.subsys}.{brokername}',
         with_tractor_log=bool(tll),
     )
-    assert log.name == _util.subsys
 
     # unblock caller
     await ctx.started()
diff --git a/piker/clearing/_ems.py b/piker/clearing/_ems.py
index 1d152926..4280dee0 100644
--- a/piker/clearing/_ems.py
+++ b/piker/clearing/_ems.py
@@ -810,11 +810,10 @@ async def _setup_persistent_emsd(
 ) -> None:
 
     if loglevel:
-        _log = get_console_log(
+        get_console_log(
             level=loglevel,
             name=subsys,
         )
-        assert _log.name == 'piker.clearing'
 
     global _router
 
diff --git a/piker/data/_daemon.py b/piker/data/_daemon.py
index 116d1346..27f27a90 100644
--- a/piker/data/_daemon.py
+++ b/piker/data/_daemon.py
@@ -86,12 +86,11 @@ async def _setup_persistent_datad(
     # their own B)
     actor: tractor.Actor = tractor.current_actor()
     tll: str = actor.loglevel
-    log = get_console_log(
+    get_console_log(
         level=loglevel or tll,
         name=f'{_util.subsys}.{brokername}',
         with_tractor_log=bool(tll),
     )
-    assert log.name == _util.subsys
 
     # XXX: ALSO enable console logging for the provider
     # backend's mod subtree (eg. `piker.brokers.ib.*`)
diff --git a/piker/log.py b/piker/log.py
index 0145debf..f5989fbf 100644
--- a/piker/log.py
+++ b/piker/log.py
@@ -36,6 +36,15 @@ from pygments import (
 _proj_name: str = 'piker'
 
 
+def _relative_name(
+    name: str|None,
+) -> str|None:
+    if name:
+        return name.removeprefix(f'{_proj_name}.')
+
+    return None
+
+
 def get_logger(
     name: str|None = None,
     **tractor_log_kwargs,
@@ -47,17 +56,9 @@ def get_logger(
     See `tractor.log.get_logger()` for details.
 
     '''
-    pkg_name: str = _proj_name
-    if (
-        name
-        and
-        pkg_name in name
-    ):
-        name: str = name.lstrip(f'{_proj_name}.')
-
     return tractor.log.get_logger(
-        name=name,
-        pkg_name=pkg_name,
+        name=_relative_name(name),
+        pkg_name=_proj_name,
         **tractor_log_kwargs,
     )
 
@@ -81,14 +82,6 @@ def get_console_log(
     You do it.. Bp
 
     '''
-    pkg_name: str = _proj_name
-    if (
-        name
-        and
-        pkg_name in name
-    ):
-        name: str = name.lstrip(f'{_proj_name}.')
-
     tll: str|None = None
     if (
         with_tractor_log is not False
@@ -111,8 +104,8 @@ def get_console_log(
 
     return tractor.log.get_console_log(
         level=level,
-        name=name,
-        pkg_name=pkg_name,
+        name=_relative_name(name),
+        pkg_name=_proj_name,
         **tractor_log_kwargs,
     )
 
diff --git a/piker/service/_daemon.py b/piker/service/_daemon.py
index e6e372df..d89bcaf2 100644
--- a/piker/service/_daemon.py
+++ b/piker/service/_daemon.py
@@ -72,7 +72,6 @@ async def maybe_spawn_daemon(
         level=loglevel,
         name=__name__,
     )
-    assert log.name == 'piker.service'
 
     # serialize access to this section to avoid
     # 2 or more tasks racing to create a daemon
diff --git a/tests/test_logging.py b/tests/test_logging.py
new file mode 100644
index 00000000..43755446
--- /dev/null
+++ b/tests/test_logging.py
@@ -0,0 +1,44 @@
+'''
+Package logger namespace regression tests.
+
+'''
+import pytest
+
+from piker.log import (
+    get_console_log,
+    get_logger,
+)
+
+
+@pytest.mark.parametrize(
+    'factory',
+    [
+        get_logger,
+        get_console_log,
+    ],
+)
+@pytest.mark.parametrize(
+    'name',
+    [
+        'piker.service._daemon',
+        'piker.paper',
+    ],
+)
+def test_package_logger_name(
+    factory,
+    name: str,
+):
+    '''
+    `str.lstrip('piker.')` treated the package prefix as a set of
+    removable characters. A submodule beginning with any of those
+    characters, such as `piker.paper`, was silently renamed to
+    `piker.aper`, while service code asserted a stale parent name.
+
+    Exercise both logger factories with service and prefix-sensitive
+    submodule names, proving they retain the exact requested package
+    namespace.
+
+    '''
+    log = factory(name=name)
+
+    assert log.name == name