diff --git a/.gitignore b/.gitignore
index 55d5b5a..471e767 100755
--- a/.gitignore
+++ b/.gitignore
@@ -255,3 +255,8 @@ dependency_links.txt
 top_level.txt
 
 .tox/
+
+# The OWID source copied into the 51Did package at build time by
+# ci/copy-owid-source.ps1. The submodule is the only copy that belongs in
+# the repository.
+fiftyone_pipeline_did/src/fiftyone_pipeline_did/_owid/
diff --git a/ci/build-package.ps1 b/ci/build-package.ps1
index aa54e6a..acbad7f 100644
--- a/ci/build-package.ps1
+++ b/ci/build-package.ps1
@@ -5,6 +5,12 @@ param (
     [string]$Version
 )
 
+# The 51Did package carries the OWID source inside itself, because the
+# dependency cannot come from a package registry. Copy it in before the
+# distributions are built, so that both the source distribution and the wheel
+# contain it. See ci/copy-owid-source.ps1 for the full reasoning.
+& "$PSScriptRoot/copy-owid-source.ps1" -RepoRoot $RepoName
+
 $packages = "fiftyone_pipeline_core", "fiftyone_pipeline_engines", "fiftyone_pipeline_engines_fiftyone", "fiftyone_pipeline_cloudrequestengine", "fiftyone_pipeline_translation", "fiftyone_pipeline_did"
 ./python/build-package-pypi.ps1 -RepoName $RepoName -Version $Version -Packages $packages
 
diff --git a/ci/build-project.ps1 b/ci/build-project.ps1
index a7589fe..a7ae240 100644
--- a/ci/build-project.ps1
+++ b/ci/build-project.ps1
@@ -3,6 +3,11 @@ param (
     [string]$RepoName
 )
 
+# The 51Did package is built from its own tox environment by the unit test
+# step, and that build needs the OWID source in place, so put it there before
+# anything builds. See ci/copy-owid-source.ps1 for the full reasoning.
+& "$PSScriptRoot/copy-owid-source.ps1" -RepoRoot $RepoName
+
 $packages = "fiftyone_pipeline_core", "fiftyone_pipeline_engines", "fiftyone_pipeline_engines_fiftyone", "fiftyone_pipeline_cloudrequestengine", "fiftyone_pipeline_translation"
 ./python/build-project.ps1 -RepoName $RepoName -Packages $packages
 
diff --git a/ci/copy-owid-source.ps1 b/ci/copy-owid-source.ps1
new file mode 100644
index 0000000..84ffbd5
--- /dev/null
+++ b/ci/copy-owid-source.ps1
@@ -0,0 +1,76 @@
+param (
+    # The root of the pipeline-python working copy. Defaults to the parent of
+    # this script, which is right for a developer checkout, and is passed
+    # explicitly by the CI scripts because they run from the workspace above
+    # the clone.
+    [string]$RepoRoot = (Split-Path $PSScriptRoot -Parent)
+)
+$ErrorActionPreference = "Stop"
+
+# Copies the OWID source into the 51Did package as the private module
+# fiftyone_pipeline_did._owid, so that a published wheel can be imported
+# without the OWID library being installed separately.
+#
+# The dependency cannot come from a package registry. The 51Degrees fork of
+# OWID is not published to PyPI, and the name "owid" on PyPI belongs to an
+# unrelated project, so declaring install_requires=["owid"] would install the
+# wrong thing. The name here carries a leading underscore so that installing
+# the 51Did package never claims the top level name "owid" on a consumer's
+# machine.
+#
+# Nothing is fetched over the network, because owid-python is a submodule and
+# CI clones with --recurse-submodules. Nothing is written back to the
+# repository either, as the copy is ignored by git and main keeps the
+# submodule as the single source of the OWID code.
+
+$owidRepo = Join-Path $RepoRoot "owid-python"
+$owidSource = Join-Path $owidRepo "owid"
+$target = Join-Path $RepoRoot `
+    "fiftyone_pipeline_did/src/fiftyone_pipeline_did/_owid"
+
+if (-not (Test-Path (Join-Path $owidSource "__init__.py"))) {
+    throw "OWID source not found at '$owidSource'. Run " +
+        "'git submodule update --init --recursive' first, or clone with " +
+        "--recurse-submodules."
+}
+
+# The commit the copy was taken from, so the notice can say exactly which
+# version of the OWID source is inside the package.
+$commit = (git -C $owidRepo rev-parse HEAD 2>$null)
+if (-not $commit) {
+    $commit = (git -C $RepoRoot rev-parse "HEAD:owid-python" 2>$null)
+}
+if (-not $commit) {
+    throw "Could not determine the owid-python commit to record in the notice."
+}
+
+if (Test-Path $target) {
+    Remove-Item -Path $target -Recurse -Force
+}
+$null = New-Item -ItemType Directory -Path $target -Force
+
+Copy-Item -Path (Join-Path $owidSource "*.py") -Destination $target -Force
+Copy-Item -Path (Join-Path $owidRepo "LICENSE") `
+    -Destination (Join-Path $target "LICENSE") -Force
+
+$notice = @"
+The Python modules in this directory are the OWID (Open Web Id) library. They
+are copied into the fiftyone_pipeline_did package at build time and are not
+part of the 51Degrees source, so they keep their own licence, which is the
+Apache License 2.0 in the LICENSE file beside this notice, and not the EUPL
+1.2 that covers the rest of the package.
+
+Copyright 2026 51 Degrees Mobile Experts Limited (51degrees.com)
+
+Taken from the 51Degrees fork of the OWID project,
+https://github.com/51Degrees/owid-python, at commit
+$commit
+which follows https://github.com/SWAN-community/owid-python.
+
+The modules are placed under the private name _owid so that installing this
+package does not claim the top level name "owid", which on PyPI belongs to an
+unrelated project. Import OWID from the fork itself rather than from here.
+"@
+Set-Content -Path (Join-Path $target "NOTICE") -Value $notice -Encoding utf8
+
+Write-Output "Copied OWID source at $commit into '$target'"
diff --git a/fiftyone_pipeline_did/MANIFEST.in b/fiftyone_pipeline_did/MANIFEST.in
index 3fed507..48e2f00 100644
--- a/fiftyone_pipeline_did/MANIFEST.in
+++ b/fiftyone_pipeline_did/MANIFEST.in
@@ -1,2 +1,7 @@
 include version.txt
 include readme.md
+# The OWID source carried inside this package under the private name _owid is
+# Apache-2.0, so its licence and the notice naming where the source came from
+# have to travel with it in both the sdist and the wheel.
+include src/fiftyone_pipeline_did/_owid/LICENSE
+include src/fiftyone_pipeline_did/_owid/NOTICE
diff --git a/fiftyone_pipeline_did/examples/creator_context_web/server.py b/fiftyone_pipeline_did/examples/creator_context_web/server.py
index 9452a23..39902a8 100644
--- a/fiftyone_pipeline_did/examples/creator_context_web/server.py
+++ b/fiftyone_pipeline_did/examples/creator_context_web/server.py
@@ -80,8 +80,9 @@
 # The package from this repository rather than a published one, so the
 # branch is what runs. When the package is installed the import succeeds
 # directly, and otherwise the package source beside this example is used,
-# which is how a checkout runs the demo without an install step. The OWID
-# library the package builds on must be installed either way (see the
+# which is how a checkout runs the demo without an install step. Running
+# from the source needs the OWID copy that ci/copy-owid-source.ps1 puts in
+# place, so run pwsh ./setup.ps1 from the repository root first (see the
 # package readme).
 try:
     from fiftyone_pipeline_did import (
diff --git a/fiftyone_pipeline_did/readme.md b/fiftyone_pipeline_did/readme.md
index e4d9fed..bb2c704 100644
--- a/fiftyone_pipeline_did/readme.md
+++ b/fiftyone_pipeline_did/readme.md
@@ -38,9 +38,34 @@ as `PROBABILISTIC`.
 
 `FodId` builds on the OWID envelope library
 ([SWAN-community/owid-python](https://github.com/SWAN-community/owid-python),
-package `owid`), consumed via the `51Degrees/owid-python` fork (git submodule;
-switch to upstream once published). `Owid` is composed, not subclassed:
-`FodId` holds an `Owid` and delegates OWID-level concerns to it.
+package `owid`), consumed via the
+[51Degrees/owid-python](https://github.com/51Degrees/owid-python) fork, which
+is a git submodule of this repository and will move to upstream once that is
+published. `Owid` is composed, not subclassed, so `FodId` holds an `Owid` and
+delegates OWID-level concerns to it.
+
+The published package does not take OWID from PyPI. The 51Degrees fork is not
+published there, and the name `owid` on PyPI belongs to an unrelated project,
+so a declared dependency would install the wrong thing. Instead
+`ci/copy-owid-source.ps1` copies the fork's source into the package as the
+private module `fiftyone_pipeline_did._owid` before the distribution is built,
+carrying the Apache-2.0 licence and a notice naming the source commit with it.
+The leading underscore keeps the top level name `owid` free on the consumer's
+machine. The only third party requirement the package declares is
+`cryptography`, which OWID uses for the signatures.
+
+Nothing changes for a developer working in this repository, because the
+submodule stays where it is and the same script puts the copy in place.
+Run `pwsh ./setup.ps1` from the repository root, or
+`git submodule update --init --recursive` followed by
+`pwsh ./ci/copy-owid-source.ps1`, before building or running the tests. The
+tests and examples import the fork under its own name, `owid`, which is how
+they build signed envelopes to test against.
+
+The two OWID types the public API refers to are re-exported from the package
+itself, so a caller never has to reach into the private module. Catch
+`fiftyone_pipeline_did.OwidError` for an OWID level failure, and use
+`fiftyone_pipeline_did.Owid` for the envelope that `FodId.from_owid` takes.
 
 ## Usage
 
diff --git a/fiftyone_pipeline_did/setup.py b/fiftyone_pipeline_did/setup.py
index f531de7..63661d2 100644
--- a/fiftyone_pipeline_did/setup.py
+++ b/fiftyone_pipeline_did/setup.py
@@ -46,16 +46,21 @@ def read(file_name):
     long_description=read("readme.md"),
     long_description_content_type='text/markdown',
     python_requires=">=3.9",
-    packages=["fiftyone_pipeline_did"],
+    packages=["fiftyone_pipeline_did", "fiftyone_pipeline_did._owid"],
     package_dir={"": "src"},
-    # OWID is provided by the 51Degrees owid-python fork, which is consumed via
-    # the git submodule / editable install (see tox.ini) rather than declared as
-    # a PyPI dependency. The name "owid" on PyPI belongs to an unrelated project,
-    # and the 51Degrees fork is not published to PyPI, so a bare
-    # install_requires=['owid'] would resolve to the wrong package. If this
-    # package is ever published standalone, depend on a 51Degrees-namespaced
-    # OWID distribution here instead.
-    install_requires=[],
+    # The OWID source is carried inside this package as the private module
+    # fiftyone_pipeline_did._owid, copied out of the 51Degrees owid-python
+    # fork by ci/copy-owid-source.ps1 before the distribution is built. It
+    # cannot
+    # come from a package registry, because the 51Degrees fork is not
+    # published to PyPI and the name "owid" there belongs to an unrelated
+    # project, so a bare install_requires=["owid"] would install the wrong
+    # thing. The module is private (leading underscore) so that installing
+    # this package never claims the top level name "owid" on a consumer's
+    # machine. Its only third party requirement is cryptography, which is
+    # declared below and does come from PyPI.
+    package_data={"fiftyone_pipeline_did._owid": ["LICENSE", "NOTICE"]},
+    install_requires=["cryptography>=41"],
     license="EUPL-1.2",
     classifiers=[
         "Development Status :: 5 - Production/Stable",
diff --git a/fiftyone_pipeline_did/src/fiftyone_pipeline_did/__init__.py b/fiftyone_pipeline_did/src/fiftyone_pipeline_did/__init__.py
index 803a5e9..d37b086 100644
--- a/fiftyone_pipeline_did/src/fiftyone_pipeline_did/__init__.py
+++ b/fiftyone_pipeline_did/src/fiftyone_pipeline_did/__init__.py
@@ -52,6 +52,12 @@
     SignatureReason,
     SignatureResult,
 )
+# The OWID library is carried inside this package as the private module
+# _owid, because it cannot be installed from a package registry (see the
+# package readme). The envelope type and the error type are re-exported here
+# so that callers have supported names for the two of them that the public
+# API refers to, as the private module itself is not part of that API.
+from ._owid import Owid, OwidError
 from .fod_id import DATE_EPOCH, FodId
 from .id_type import IdType
 
@@ -71,4 +77,6 @@
     "DidArgumentError",
     "DidNotSupportedError",
     "DEFAULT_ENDPOINT",
+    "Owid",
+    "OwidError",
 ]
diff --git a/fiftyone_pipeline_did/src/fiftyone_pipeline_did/did_client.py b/fiftyone_pipeline_did/src/fiftyone_pipeline_did/did_client.py
index 6bcd9bd..996fac3 100644
--- a/fiftyone_pipeline_did/src/fiftyone_pipeline_did/did_client.py
+++ b/fiftyone_pipeline_did/src/fiftyone_pipeline_did/did_client.py
@@ -54,7 +54,7 @@
 from enum import Enum
 from typing import Any, Callable, Dict, List, Optional, Tuple, Union
 
-from owid import Version
+from ._owid import Version
 
 from .fod_id import DATE_EPOCH, FodId
 from .id_type import IdType
diff --git a/fiftyone_pipeline_did/src/fiftyone_pipeline_did/fod_id.py b/fiftyone_pipeline_did/src/fiftyone_pipeline_did/fod_id.py
index f0ff59d..ded5ad1 100644
--- a/fiftyone_pipeline_did/src/fiftyone_pipeline_did/fod_id.py
+++ b/fiftyone_pipeline_did/src/fiftyone_pipeline_did/fod_id.py
@@ -24,7 +24,7 @@
 
 from datetime import datetime, timezone
 
-from owid import Owid, Version
+from ._owid import Owid, Version
 
 from .id_type import IdType
 
@@ -39,8 +39,9 @@ class FodId:
     returned by the 51Degrees Cloud service.
 
     A 51Did is described at three levels. The **51Did** is the identifier as a
-    whole. The **envelope** is the signed :class:`owid.Owid` that carries it
-    (version, domain, date, payload, signature), re-issued fresh on every call.
+    whole. The **envelope** is the signed
+    :class:`~fiftyone_pipeline_did.Owid` that carries it (version, domain,
+    date, payload, signature), re-issued fresh on every call.
     The **value** is the stable, comparable part of the payload after the Flags
     and License Id, exposed as :attr:`hash`. Two 51Dids for the same inputs
     share the same value even though their envelopes differ. *Compare values,
@@ -77,8 +78,8 @@ class FodId:
     PAYLOAD_LENGTH = HASH_OFFSET + HASH_LENGTH
 
     def __init__(self, owid: Owid) -> None:
-        """Promotes an already-parsed :class:`owid.Owid` into a 51Did by
-        unpacking its payload.
+        """Promotes an already-parsed :class:`~fiftyone_pipeline_did.Owid`
+        into a 51Did by unpacking its payload.
 
         The OWID is **copied** (round-tripped through its byte form), not
         aliased, so a ``FodId`` can never desync from its envelope if the caller
@@ -87,8 +88,8 @@ def __init__(self, owid: Owid) -> None:
 
         Raises :class:`TypeError` if ``owid`` is ``None``, :class:`ValueError`
         if the payload is shorter than the minimum for its identifier type, and
-        :class:`owid.OwidError` if the OWID cannot be serialized (e.g. it is
-        unsigned).
+        :class:`~fiftyone_pipeline_did.OwidError` if the OWID cannot be
+        serialized (e.g. it is unsigned).
         """
         if owid is None:
             raise TypeError("owid must not be None")
@@ -141,7 +142,8 @@ def from_base64(cls, base64: str) -> "FodId":
         never converts an identifier it received from a link.
 
         Raises :class:`TypeError` if ``base64`` is ``None`` and
-        :class:`owid.OwidError` if it is not valid base64 or not a valid OWID.
+        :class:`~fiftyone_pipeline_did.OwidError` if it is not valid base64
+        or not a valid OWID.
         """
         if base64 is None:
             raise TypeError("base64 must not be None")
@@ -177,7 +179,8 @@ def from_byte_array(cls, buffer: bytes) -> "FodId":
         """Parses a 51Did from the raw bytes of an OWID envelope.
 
         Raises :class:`TypeError` if ``buffer`` is ``None`` and
-        :class:`owid.OwidError` if the bytes are not a valid OWID.
+        :class:`~fiftyone_pipeline_did.OwidError` if the bytes are not a
+        valid OWID.
         """
         if buffer is None:
             raise TypeError("buffer must not be None")
diff --git a/fiftyone_pipeline_did/tests/test_fodid.py b/fiftyone_pipeline_did/tests/test_fodid.py
index 7e1388a..517acaf 100644
--- a/fiftyone_pipeline_did/tests/test_fodid.py
+++ b/fiftyone_pipeline_did/tests/test_fodid.py
@@ -24,9 +24,9 @@
 import unittest
 from datetime import datetime, timezone
 
-from owid import Owid, Crypto, Creator, OwidError
+from owid import Owid, Crypto, Creator
 
-from fiftyone_pipeline_did import FodId, IdType
+from fiftyone_pipeline_did import FodId, IdType, OwidError
 
 TEST_DOMAIN = "51degrees.com"
 # 0xA5: usage bits plus the HashedEmail type tag in bits 6-7.
diff --git a/setup.ps1 b/setup.ps1
index 03a86e7..f986699 100644
--- a/setup.ps1
+++ b/setup.ps1
@@ -1,6 +1,12 @@
+# The 51Did package builds against the OWID source, which lives in the
+# owid-python submodule and is copied into the package rather than installed
+# from a package registry. See ci/copy-owid-source.ps1 for why.
+& "$PSScriptRoot/ci/copy-owid-source.ps1"
+
 python -m pip install -e fiftyone_pipeline_cloudrequestengine/
 python -m pip install -e fiftyone_pipeline_core/
 python -m pip install -e fiftyone_pipeline_translation/
 python -m pip install -e fiftyone_pipeline_engines/
 python -m pip install -e fiftyone_pipeline_engines_fiftyone/
+python -m pip install -e owid-python/
 python -m pip install flask