diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7f09d9ca3..9287352e1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -119,9 +119,8 @@ and this project adheres to
   endpoints since the history panel started reading the collaboration server's
   `activity` and `changeset` routes instead. Gone with them:
   `Document.get_versions_slice`, `Document.delete_version`, the `version_id`
-  argument of
-  `get_content_response`, the `DOCUMENT_VERSIONS_PAGE_SIZE` setting, and the
-  `versions_retrieve` and `versions_destroy` abilities
+  argument of `get_content_response`, the `DOCUMENT_VERSIONS_PAGE_SIZE`
+  setting, and the `versions_retrieve` and `versions_destroy` abilities
 
   The `versions_list` ability stays and keeps its meaning — may this user see
   this document's history — now as a pure gate rather than the permission for
@@ -129,6 +128,21 @@ and this project adheres to
   collaboration server reads it to decide whether to ask this backend when the
   caller's access began, which is where the history it serves starts
 
+- 🔥(backend) remove `Document.content`. The collaboration server has owned the
+  content of the documents since the migration, and the version endpoints
+  removed above were the last thing in Django that read the legacy `{id}/file`
+  object; nothing had written it for as long. Gone with the property: its
+  setter, `Document.save_content`, `Document.get_content_response` and the
+  `save()` override that existed only to write the content — a document is
+  saved by `Model.save` alone now, and creating one no longer costs a `HEAD`
+  and a `PUT` against the object storage
+
+  The objects are untouched and must stay: the collaboration server seeds a
+  room from `{id}/file` on first access (`SOFT_MIGRATION`) and replays its
+  versions to rebuild the history. `Document.file_key` stays with them, and
+  `clean_document` goes on purging that object so that a document it reset
+  cannot be seeded back from what it left behind
+
 ### Fixed
 
 - 🐛(frontend) stop reconnecting to the collaboration server when it has refused
diff --git a/UPGRADE.md b/UPGRADE.md
index 2a48a7237..018fcec78 100644
--- a/UPGRADE.md
+++ b/UPGRADE.md
@@ -85,8 +85,9 @@ upgrade, in the order they are done, and end with the API changes.
   2. Then backfill the corpus, which the lazy seeding never finishes on its own
      — a document nobody opens stays in S3 forever. `python manage.py
      migrate_documents` hands every document to the collaboration server, which
-     replays its **full** S3 version history rather than its last snapshot, so
-     `/documents/{id}/versions/` and the history the editor shows agree. It is
+     replays its **full** S3 version history rather than its last snapshot,
+     so the history the editor shows reaches back to the document's first save
+     instead of beginning the day it reached the collaboration server. It is
      bounded (`--concurrency`, `--rate`, `--limit`, `--created-before`),
      resumable and safe to re-run: what became of every document is recorded in
      the new `impress_document_migration` table, a document the server refused
@@ -98,9 +99,18 @@ upgrade, in the order they are done, and end with the API changes.
   migrated — but an unmigrated document then opens as an *empty* room over
   content that is alive in S3.
 
-  Keep the media bucket, its objects and its versioning either way:
-  `/documents/{id}/versions/` still serves the version history from there, and
-  the full migration replays it.
+  The media bucket itself is not going anywhere: the attachments of the
+  documents live in it, under `{document-id}/attachments/`, and the backend
+  goes on uploading them, signing urls for them and scanning them through the
+  S3 API. What this upgrade adds to it is temporary, and has to be kept either
+  way: the legacy `{document-id}/file` objects **and their versions**. Django
+  has let go of that key — it neither reads nor writes it anymore, and the
+  endpoints that used to serve its versions are removed below — but the two
+  steps above are what read it now, the lazy seed taking its newest version and
+  the backfill replaying every one of them. They are the whole record of what
+  the documents were before the collaboration server, so leave the bucket
+  versioned and those objects in place until the backfill has covered the
+  corpus; there is no way back from deleting them.
 
 - ⚠️ **The websocket url changed**, and so does what `/collaboration/` is
   routed to. The room is appended by the client, and the last segment of the
@@ -242,6 +252,22 @@ upgrade, in the order they are done, and end with the API changes.
   it. `/api/v1.0/documents/{document_id}/formatted-content/` is not affected.
   The `CONTENT_METADATA_CACHE_TIMEOUT` setting only tuned the cache of the
   removed `GET` and is no longer read, you can drop it from your configuration.
+- The endpoints `GET /api/v1.0/documents/{document_id}/versions/` and `GET,
+  DELETE /api/v1.0/documents/{document_id}/versions/{version_id}/` are removed.
+  They listed and served the S3 object versions of `{document_id}/file`, the
+  key the content of a document used to be stored under; nothing has written it
+  since the content moved to the collaboration server, so what they listed was
+  frozen at each document's migration date. The editor reads the history from
+  the collaboration server instead. If you integrate with Docs, stop calling
+  them: the `versions_retrieve` and `versions_destroy` abilities disappear from
+  the document payload along with them, and the `DOCUMENT_VERSIONS_PAGE_SIZE`
+  setting is no longer read, you can drop it from your configuration.
+
+  The `versions_list` ability stays, and keeps its meaning — may this user see
+  this document's history. It is a gate now rather than the permission for an
+  endpoint of ours: the frontend hides the history menu without it, and the
+  collaboration server reads it to decide whether to ask this backend when the
+  caller's access began, which is where the history it serves starts.
 - The JWKS of the resource server moved from `/api/{version}/jwks` to
   `/external_api/{version}/jwks`, alongside the rest of the resource server
   endpoints. `/api/{version}/jwks` now publishes the public key validating the
diff --git a/src/backend/core/factories.py b/src/backend/core/factories.py
index d918c073f..7d3d49054 100644
--- a/src/backend/core/factories.py
+++ b/src/backend/core/factories.py
@@ -32,8 +32,8 @@ YDOC_HELLO_WORLD_BASE64 = (
 
 # The same document as the raw Yjs update the collaboration server serves, which
 # is what a test faking `YHubService.get_ydoc` answers with (see the
-# `yhub_content` fixture). The base64 above is the legacy object storage format,
-# only the tests still about that storage have a use for it.
+# `yhub_content` fixture). The base64 above is what a test expecting the text of
+# that document reads it from.
 YDOC_HELLO_WORLD_UPDATE = base64.b64decode(YDOC_HELLO_WORLD_BASE64)
 
 
@@ -93,8 +93,7 @@ class DocumentFactory(factory.django.DjangoModelFactory):
     excerpt = factory.Sequence(lambda n: f"excerpt{n}")
     # No content: the collaboration server holds it, and a document built here
     # is one it knows nothing of. A test needing a document with content fakes
-    # what the collaboration server serves for it (`YHubService.get_ydoc`), and
-    # only the ones about the legacy object storage itself pass `content=`.
+    # what the collaboration server serves for it (`YHubService.get_ydoc`).
     creator = factory.SubFactory(UserFactory)
     deleted_at = None
     link_reach = factory.fuzzy.FuzzyChoice(
diff --git a/src/backend/core/models.py b/src/backend/core/models.py
index 483eabc7d..3e9c06f4e 100644
--- a/src/backend/core/models.py
+++ b/src/backend/core/models.py
@@ -4,7 +4,6 @@ Declare and configure the models for the impress core application
 
 # pylint: disable=too-many-lines
 
-import hashlib
 import smtplib
 import uuid
 from datetime import timedelta
@@ -17,8 +16,6 @@ from django.contrib.postgres.fields import ArrayField
 from django.contrib.postgres.indexes import GinIndex
 from django.contrib.sites.models import Site
 from django.core.cache import cache
-from django.core.files.base import ContentFile
-from django.core.files.storage import default_storage
 from django.core.mail import send_mail
 from django.db import models, transaction
 from django.db.models import Count
@@ -29,7 +26,6 @@ from django.utils.functional import cached_property
 from django.utils.translation import get_language, override
 from django.utils.translation import gettext_lazy as _
 
-from botocore.exceptions import ClientError
 from rest_framework.exceptions import ValidationError
 from timezone_field import TimeZoneField
 from treebeard.mp_tree import MP_Node, MP_NodeManager, MP_NodeQuerySet
@@ -955,7 +951,7 @@ class DocumentManager(MP_NodeManager.from_queryset(DocumentQuerySet)):
 
 # pylint: disable=too-many-public-methods
 class Document(MP_Node, BaseModel):
-    """Pad document carrying the content."""
+    """Pad document, the content of which lives in the collaboration server."""
 
     title = models.CharField(_("title"), max_length=255, null=True, blank=True)
     excerpt = models.TextField(_("excerpt"), max_length=300, null=True, blank=True)
@@ -993,8 +989,6 @@ class Document(MP_Node, BaseModel):
         null=True,
     )
 
-    _content = None
-
     # Tree structure
     alphabet = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
     steplen = 7  # nb siblings max: 3,521,614,606,208
@@ -1033,39 +1027,6 @@ class Document(MP_Node, BaseModel):
         self._ancestors_link_definition = None
         self._computed_link_definition = None
 
-    def save(self, *args, **kwargs):
-        """Write content to object storage only if _content has changed."""
-        super().save(*args, **kwargs)
-        if self._content:
-            self.save_content(self._content)
-
-    def save_content(self, content):
-        """Save content to object storage."""
-
-        file_key = self.file_key
-        bytes_content = content.encode("utf-8")
-
-        # Attempt to directly check if the object exists using the storage client.
-        try:
-            response = default_storage.connection.meta.client.head_object(
-                Bucket=default_storage.bucket_name, Key=file_key
-            )
-        except ClientError as excpt:
-            # If the error is a 404, the object doesn't exist, so we should create it.
-            if excpt.response["Error"]["Code"] == "404":
-                has_changed = True
-            else:
-                raise
-        else:
-            # Compare the existing ETag with the MD5 hash of the new content.
-            has_changed = (
-                response["ETag"].strip('"') != hashlib.md5(bytes_content).hexdigest()  # noqa: S324
-            )
-
-        if has_changed:
-            content_file = ContentFile(bytes_content)
-            default_storage.save(file_key, content_file)
-
     def is_leaf(self):
         """
         :returns: True if the node is has no children
@@ -1083,35 +1044,17 @@ class Document(MP_Node, BaseModel):
 
     @property
     def file_key(self):
-        """Key of the object storage file to which the document content is stored"""
+        """
+        Key of the legacy object storage file that used to hold the content.
+
+        The collaboration server owns the content now, and Django neither reads
+        nor writes this object any more. The key outlives it: the collaboration
+        server seeds a room from that object on first access and replays its
+        versions to rebuild the history, and `clean_document` purges it so that
+        a document it reset cannot be seeded back from what it left behind.
+        """
         return f"{self.key_base}/file"
 
-    @property
-    def content(self):
-        """Return the json content from object storage if available"""
-        if self._content is None and self.id:
-            try:
-                response = self.get_content_response()
-            except FileNotFoundError, ClientError:
-                pass
-            else:
-                self._content = response["Body"].read().decode("utf-8")
-        return self._content
-
-    @content.setter
-    def content(self, content):
-        """Cache the content, don't write to object storage yet"""
-        if not isinstance(content, str):
-            raise ValueError("content should be a string.")
-
-        self._content = content
-
-    def get_content_response(self):
-        """Get the content of the document from object storage"""
-        return default_storage.connection.meta.client.get_object(
-            Bucket=default_storage.bucket_name, Key=self.file_key
-        )
-
     def get_nb_accesses_cache_key(self):
         """Generate a unique cache key for each document."""
         return f"document_{self.id!s}_nb_accesses"
diff --git a/src/backend/core/tests/documents/test_api_documents_children_create.py b/src/backend/core/tests/documents/test_api_documents_children_create.py
index 679edca8f..8cb92dd70 100644
--- a/src/backend/core/tests/documents/test_api_documents_children_create.py
+++ b/src/backend/core/tests/documents/test_api_documents_children_create.py
@@ -354,7 +354,6 @@ def test_api_documents_children_create_with_docx_file_success(
     children = Document.objects.get(pk=response.json()["id"])
     assert children.title == "My Important Document.docx"
     # the content is saved by the collaboration server, not by Django
-    assert children.content is None
     mock_yhub.assert_called_once_with(user=user)
     mock_yhub.return_value.create_ydoc.assert_called_once_with(children, converted_yjs)
 
diff --git a/src/backend/core/tests/documents/test_api_documents_content_updated.py b/src/backend/core/tests/documents/test_api_documents_content_updated.py
index fa7b5ac69..dd093d3de 100644
--- a/src/backend/core/tests/documents/test_api_documents_content_updated.py
+++ b/src/backend/core/tests/documents/test_api_documents_content_updated.py
@@ -222,8 +222,7 @@ def test_api_documents_content_updated_rolled_key(yhub_jwks):
 def test_api_documents_content_updated():
     """The collaboration server should be able to refresh the date of a document."""
     with freeze_time("2026-08-01 12:00:00"):
-        # no content: writing one to S3 under a frozen clock breaks its signature
-        document = factories.DocumentFactory(title="my document", content="")
+        document = factories.DocumentFactory(title="my document")
 
     with freeze_time("2026-08-06 12:00:00"):
         response = APIClient().post(
diff --git a/src/backend/core/tests/documents/test_api_documents_create_for_owner.py b/src/backend/core/tests/documents/test_api_documents_create_for_owner.py
index c27d57b16..c9c45a938 100644
--- a/src/backend/core/tests/documents/test_api_documents_create_for_owner.py
+++ b/src/backend/core/tests/documents/test_api_documents_create_for_owner.py
@@ -219,7 +219,6 @@ def test_api_documents_create_for_owner_existing(mock_convert_md, mock_yhub):
 
     assert document.title == "My Document"
     # the content is saved by the collaboration server, not by Django
-    assert document.content is None
     mock_yhub.return_value.create_ydoc.assert_called_once_with(
         document, CONVERTED_CONTENT
     )
@@ -289,7 +288,6 @@ def test_api_documents_create_for_owner_new_user(mock_convert_md, mock_yhub):
 
     assert document.title == "My Document"
     # the content is saved by the collaboration server, not by Django
-    assert document.content is None
     mock_yhub.return_value.create_ydoc.assert_called_once_with(
         document, CONVERTED_CONTENT
     )
@@ -401,7 +399,6 @@ def test_api_documents_create_for_owner_existing_user_email_no_sub_with_fallback
 
     assert document.title == "My Document"
     # the content is saved by the collaboration server, not by Django
-    assert document.content is None
     mock_yhub.return_value.create_ydoc.assert_called_once_with(
         document, CONVERTED_CONTENT
     )
@@ -503,7 +500,6 @@ def test_api_documents_create_for_owner_new_user_no_sub_no_fallback_allow_duplic
 
     assert document.title == "My Document"
     # the content is saved by the collaboration server, not by Django
-    assert document.content is None
     mock_yhub.return_value.create_ydoc.assert_called_once_with(
         document, CONVERTED_CONTENT
     )
diff --git a/src/backend/core/tests/documents/test_api_documents_create_with_file.py b/src/backend/core/tests/documents/test_api_documents_create_with_file.py
index 89066c965..4bf07a940 100644
--- a/src/backend/core/tests/documents/test_api_documents_create_with_file.py
+++ b/src/backend/core/tests/documents/test_api_documents_create_with_file.py
@@ -76,10 +76,9 @@ def test_api_documents_create_with_docx_file_success(mock_convert, mock_yhub, se
     assert response.status_code == 201
     document = Document.objects.get()
     assert document.title == "My Important Document.docx"
-    # the content is saved by the collaboration server, not by Django
-    assert document.content is None
     assert document.accesses.filter(role="owner", user=user).exists()
 
+    # the content is saved by the collaboration server, not by Django
     mock_yhub.assert_called_once_with(user=user)
     mock_yhub.return_value.create_ydoc.assert_called_once_with(document, converted_yjs)
 
@@ -176,10 +175,9 @@ def test_api_documents_create_with_markdown_file_success(
     assert response.status_code == 201
     document = Document.objects.get()
     assert document.title == "readme.md"
-    # the content is saved by the collaboration server, not by Django
-    assert document.content is None
     assert document.accesses.filter(role="owner", user=user).exists()
 
+    # the content is saved by the collaboration server, not by Django
     mock_yhub.return_value.create_ydoc.assert_called_once_with(document, converted_yjs)
 
     # Verify the converter was called correctly
@@ -383,7 +381,6 @@ def test_api_documents_create_without_file_still_works():
     assert response.status_code == 201
     document = Document.objects.get()
     assert document.title == "Regular document without file"
-    assert document.content is None
     assert document.accesses.filter(role="owner", user=user).exists()
 
     mock_capture.assert_called_once_with(
@@ -465,7 +462,6 @@ def test_api_documents_create_with_file_preserves_content_format(
 
     # The update is sent untouched, it is not base64 encoded on the way
     mock_yhub.return_value.create_ydoc.assert_called_once_with(document, converted_yjs)
-    assert document.content is None
 
     # The successful conversion should be tracked in PostHog
     mock_capture.assert_any_call(
diff --git a/src/backend/core/tests/documents/test_api_documents_duplicate.py b/src/backend/core/tests/documents/test_api_documents_duplicate.py
index 7ce23dfda..0dadc4f82 100644
--- a/src/backend/core/tests/documents/test_api_documents_duplicate.py
+++ b/src/backend/core/tests/documents/test_api_documents_duplicate.py
@@ -145,7 +145,6 @@ def test_api_documents_duplicate_success(index, mock_yhub):
     duplicated_document = models.Document.objects.get(id=response.json()["id"])
     assert duplicated_document.title == "Copy of document with an image"
     # the content is copied through the collaboration server
-    assert duplicated_document.content is None
     mock_yhub.return_value.create_ydoc.assert_called_once_with(
         duplicated_document, update
     )
@@ -248,7 +247,6 @@ def test_api_documents_duplicate_with_accesses_admin(role, mock_yhub):
     duplicated_document = models.Document.objects.get(id=response.json()["id"])
     assert duplicated_document.title == "Copy of document with accesses"
     # the content is copied through the collaboration server
-    assert duplicated_document.content is None
     mock_yhub.return_value.create_ydoc.assert_called_once_with(
         duplicated_document, YDOC_HELLO_WORLD_UPDATE
     )
@@ -307,7 +305,6 @@ def test_api_documents_duplicate_with_accesses_non_admin(role, mock_yhub):
     duplicated_document = models.Document.objects.get(id=response.json()["id"])
     assert duplicated_document.title == "Copy of document with accesses"
     # the content is copied through the collaboration server
-    assert duplicated_document.content is None
     mock_yhub.return_value.create_ydoc.assert_called_once_with(
         duplicated_document, YDOC_HELLO_WORLD_UPDATE
     )
@@ -359,7 +356,6 @@ def test_api_documents_duplicate_non_root_document(role, mock_yhub):
     duplicated_document = models.Document.objects.get(id=response.json()["id"])
     assert duplicated_document.title == "Copy of document with accesses"
     # the content is copied through the collaboration server
-    assert duplicated_document.content is None
     mock_yhub.return_value.create_ydoc.assert_called_once_with(
         duplicated_document, YDOC_HELLO_WORLD_UPDATE
     )
@@ -636,8 +632,6 @@ def test_api_documents_duplicate_with_descendants_and_attachments(mock_yhub):
     assert dup_child.attachments == [image_key_child]
 
     # the content of the whole subtree is copied through the collaboration server
-    assert duplicated_root.content is None
-    assert dup_child.content is None
     assert mock_yhub.return_value.create_ydoc.call_args_list == [
         mock.call(duplicated_root, root_update),
         mock.call(dup_child, child_update),
diff --git a/src/backend/core/tests/external_api/test_external_api_documents.py b/src/backend/core/tests/external_api/test_external_api_documents.py
index 183b092ed..ca154870c 100644
--- a/src/backend/core/tests/external_api/test_external_api_documents.py
+++ b/src/backend/core/tests/external_api/test_external_api_documents.py
@@ -302,10 +302,9 @@ def test_external_api_documents_create_with_markdown_file_success(
     document = models.Document.objects.get(id=data["id"])
 
     assert document.title == "readme.md"
-    # the content is saved by the collaboration server, not by Django
-    assert document.content is None
     assert document.accesses.filter(role="owner", user=user_specific_sub).exists()
 
+    # the content is saved by the collaboration server, not by Django
     mock_yhub.assert_called_once_with(user=user_specific_sub)
     mock_yhub.return_value.create_ydoc.assert_called_once_with(document, converted_yjs)
 
diff --git a/src/backend/core/tests/test_models_documents.py b/src/backend/core/tests/test_models_documents.py
index 14f6d920d..1f5fd327f 100644
--- a/src/backend/core/tests/test_models_documents.py
+++ b/src/backend/core/tests/test_models_documents.py
@@ -12,7 +12,6 @@ from django.contrib.auth.models import AnonymousUser
 from django.core import mail
 from django.core.cache import cache
 from django.core.exceptions import ValidationError
-from django.core.files.storage import default_storage
 from django.test.utils import override_settings
 from django.utils import timezone
 
@@ -908,34 +907,6 @@ def test_models_document_get_abilities_ai_access_public(is_authenticated, reach)
     assert abilities["ai_translate"] == is_authenticated
 
 
-def test_models_documents_version_duplicate():
-    """A new version should be created in object storage only if the content has changed."""
-    document = factories.DocumentFactory(content=factories.YDOC_HELLO_WORLD_BASE64)
-
-    file_key = str(document.pk)
-    response = default_storage.connection.meta.client.list_object_versions(
-        Bucket=default_storage.bucket_name, Prefix=file_key
-    )
-    assert len(response["Versions"]) == 1
-
-    # Save again with the same content
-    document.save()
-
-    response = default_storage.connection.meta.client.list_object_versions(
-        Bucket=default_storage.bucket_name, Prefix=file_key
-    )
-    assert len(response["Versions"]) == 1
-
-    # Save modified content
-    document.content = "new content"
-    document.save()
-
-    response = default_storage.connection.meta.client.list_object_versions(
-        Bucket=default_storage.bucket_name, Prefix=file_key
-    )
-    assert len(response["Versions"]) == 2
-
-
 def test_models_documents__email_invitation__success():
     """
     The email invitation is sent successfully.
diff --git a/src/backend/demo/tests/test_commands_create_demo.py b/src/backend/demo/tests/test_commands_create_demo.py
index 8c2e58566..cdb2acd9c 100644
--- a/src/backend/demo/tests/test_commands_create_demo.py
+++ b/src/backend/demo/tests/test_commands_create_demo.py
@@ -44,14 +44,12 @@ def test_commands_create_demo(collaboration_server):
     assert models.Document.objects.count() >= 10
     assert models.DocumentAccess.objects.count() > 10
 
-    # every document was seeded with its content in the collaboration server,
-    # and nothing was written to the object storage
+    # every document was seeded with its content in the collaboration server
     assert collaboration_server.call_count == 10
     seeded = {call.args[0].id for call in collaboration_server.call_args_list}
     assert seeded == set(models.Document.objects.values_list("id", flat=True))
     for call in collaboration_server.call_args_list:
         document, update = call.args
-        assert document.content is None
 
         # the structure BlockNote stores, so the editor opens a real document
         xml = yjs_to_xml(update)