diff --git a/Makefile b/Makefile
index 6d37aac..5d76852 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: help sync migrate run test lint shell check test-usecases test-browser setup-usecases
+.PHONY: help sync migrate run test lint shell check test-usecases test-browser setup-usecases check-communication
 
 .DEFAULT_GOAL := help
 
@@ -36,3 +36,6 @@ test-browser: ## Browser journeys against isolated test app
 
 check: lint ## Full lint/regression gate, including every established browser journey
 	uv run pytest --verify-usecases -m '' --junitxml=var/test-results/check.xml
+
+check-communication: ## Send-free owner retry/privacy checks; set EMAIL_CONNECT_ROOT
+	uv run python scripts/check-communication.py --owner "$(EMAIL_CONNECT_ROOT)"
diff --git a/coulomb_social/apps/core/urls.py b/coulomb_social/apps/core/urls.py
index 4f0cc6e..2f0df2e 100644
--- a/coulomb_social/apps/core/urls.py
+++ b/coulomb_social/apps/core/urls.py
@@ -8,4 +8,6 @@ urlpatterns = [
     path("", views.landing, name="landing"),
     path("app/", views.app_home, name="app_home"),
     path("account/session/", views.account_session, name="account_session"),
+    path("account/data/", views.account_data, name="account_data"),
+    path("account/export/", views.account_export, name="account_export"),
 ]
diff --git a/coulomb_social/apps/core/views.py b/coulomb_social/apps/core/views.py
index 99b10f9..fe0d6d7 100644
--- a/coulomb_social/apps/core/views.py
+++ b/coulomb_social/apps/core/views.py
@@ -1,8 +1,19 @@
+from django.contrib import messages
+from django.contrib.auth import logout
 from django.contrib.auth.decorators import login_required
 from django.http import HttpRequest, HttpResponse, HttpResponseForbidden, JsonResponse
 from django.shortcuts import redirect, render
+from django.views.decorators.http import require_http_methods, require_safe
 
+from coulomb_social.apps.members.portability import (
+    delete_local_member,
+    deletion_blockers,
+    export_member,
+    has_foreign_ownership,
+    retained_spaces,
+)
 from coulomb_social.apps.spaces.assets import local_asset_url
+from coulomb_social.apps.spaces.pageops import PageOpsError
 from coulomb_social.apps.spaces.services import spaces_for_member
 
 from .principal import build_principal
@@ -57,3 +68,43 @@ def account_session(request: HttpRequest) -> HttpResponse:
 
 def healthz(_request: HttpRequest) -> JsonResponse:
     return JsonResponse({"status": "ok", "service": "coulomb-social"})
+
+
+@login_required
+@require_http_methods(["GET", "POST"])
+def account_data(request):
+    principal = build_principal(request, authz_resource_id="account_data")
+    member = principal.get("member")
+    if not principal["authz_allow"] or member is None:
+        return HttpResponseForbidden("Local account access unavailable.")
+    if request.method == "POST":
+        try:
+            if request.POST.get("confirmation") != "DELETE":
+                raise PageOpsError("Type DELETE to confirm local account removal")
+            delete_local_member(member)
+        except PageOpsError as exc:
+            messages.error(request, exc.message)
+        else:
+            logout(request)
+            messages.success(request, "Your local account was removed. Shared content is retained.")
+            return redirect("core:landing")
+    response = render(request, "core/account_data.html", {
+        "principal": principal, "member": member,
+        "retained_spaces": retained_spaces(member), "blockers": deletion_blockers(member),
+        "ownership_review": has_foreign_ownership(member),
+    })
+    response["Cache-Control"] = "private, no-store"
+    return response
+
+
+@login_required
+@require_safe
+def account_export(request):
+    principal = build_principal(request, authz_resource_id="account_export")
+    member = principal.get("member")
+    if not principal["authz_allow"] or member is None:
+        return HttpResponseForbidden("Local account access unavailable.")
+    response = JsonResponse(export_member(member), json_dumps_params={"indent": 2})
+    response["Content-Disposition"] = 'attachment; filename="coulomb-account.json"'
+    response["Cache-Control"] = "private, no-store"
+    return response
diff --git a/coulomb_social/apps/members/portability.py b/coulomb_social/apps/members/portability.py
new file mode 100644
index 0000000..e3f2a52
--- /dev/null
+++ b/coulomb_social/apps/members/portability.py
@@ -0,0 +1,82 @@
+"""App-local portability. Platform identity and shared content stay with their owners."""
+
+from django.db import transaction
+from django.db.models import Q
+
+from coulomb_social.apps.spaces import pageops
+from coulomb_social.apps.spaces.models import Space, SpaceMembership
+from coulomb_social.apps.spaces.pageops import PageOpsError
+
+from .models import Member
+
+
+def retained_spaces(member):
+    """Include archived spaces: archiving does not abandon their ownership."""
+    return Space.objects.filter(
+        Q(created_by=member) | Q(memberships__member=member, memberships__role="owner"),
+        tenant_id=member.tenant_id,
+    ).distinct().order_by("pk")
+
+
+def has_foreign_ownership(member):
+    return Space.objects.filter(created_by=member).exclude(tenant_id=member.tenant_id).exists()
+
+
+def deletion_blockers(member):
+    blockers = []
+    for space in retained_spaces(member):
+        successor = SpaceMembership.objects.filter(
+            space=space, role="owner", member__tenant_id=space.tenant_id,
+            member__user__is_active=True,
+        ).exclude(member=member).exists()
+        if not successor:
+            blockers.append(space)
+    return blockers
+
+
+def export_member(member):
+    """Only the requesting member's personal records; no tokens or other members."""
+    grants = SpaceMembership.objects.filter(member=member, space__tenant_id=member.tenant_id)
+    return {
+        "schema_version": 1,
+        "scope": "coulomb-social app-local records",
+        "member": {
+            field: str(getattr(member, field) or "") for field in (
+                "id", "tenant_id", "issuer", "subject", "user_engine_user_id",
+                "display_name", "email", "created_at", "updated_at", "last_login_at",
+            )
+        },
+        "user": {field: str(getattr(member.user, field) or "") for field in (
+            "id", "username", "email", "full_name", "date_joined",
+        )},
+        "memberships": [
+            {"space_id": str(g.space_id), "space_slug": g.space.slug, "role": g.role,
+             "created_at": g.created_at.isoformat()} for g in grants.select_related("space")
+        ],
+        "created_spaces": [
+            {"id": str(s.pk), "slug": s.slug, "title": s.title, "is_active": s.is_active}
+            for s in Space.objects.filter(created_by=member, tenant_id=member.tenant_id)
+        ],
+        "retention": (
+            "Shared pages and assets remain in their spaces. Backups follow operator retention."
+        ),
+        "platform_identity": "NetKingdom and user-engine records are managed separately.",
+    }
+
+
+@pageops.content_writer
+@transaction.atomic
+def delete_local_member(member):
+    # Serialize against sharing on the retained spaces, then against grants to
+    # this member. The FK cascades remove all grants and the local session user.
+    ids = list(retained_spaces(member).values_list("pk", flat=True))
+    list(Space.objects.filter(pk__in=ids).order_by("pk").select_for_update())
+    member = Member.objects.select_for_update().filter(pk=member.pk).first()
+    if member is None:
+        return
+    if has_foreign_ownership(member):
+        raise PageOpsError("An inconsistent ownership record needs operator review before removal")
+    if deletion_blockers(member):
+        raise PageOpsError("Give another active member owner access to every retained space first")
+    Space.objects.filter(created_by=member).update(created_by=None)
+    member.user.delete()
diff --git a/coulomb_social/apps/spaces/admin.py b/coulomb_social/apps/spaces/admin.py
index 4c23fc0..19990b5 100644
--- a/coulomb_social/apps/spaces/admin.py
+++ b/coulomb_social/apps/spaces/admin.py
@@ -1,5 +1,6 @@
 from django.contrib import admin
 
+from . import pageops
 from .models import Space, SpaceMembership
 
 
@@ -11,6 +12,11 @@ class SpaceMembershipInline(admin.TabularInline):
 
 @admin.register(Space)
 class SpaceAdmin(admin.ModelAdmin):
+    def save_model(self, request, obj, form, change):
+        with pageops.content_write_lock():
+            obj.full_clean()
+            super().save_model(request, obj, form, change)
+
     list_display = (
         "title",
         "slug",
diff --git a/coulomb_social/apps/spaces/import_tree.py b/coulomb_social/apps/spaces/import_tree.py
index 023728d..f930980 100644
--- a/coulomb_social/apps/spaces/import_tree.py
+++ b/coulomb_social/apps/spaces/import_tree.py
@@ -90,6 +90,10 @@ def validate_space_tree(
             raise pageops.PageOpsError("Destination must not be a symlink")
     if dest.exists() and not replace:
         raise pageops.PageOpsError("Destination already exists; pass replace=True to overwrite")
+    if dest.exists() and pageops.page_aliases(space_slug):
+        raise pageops.PageOpsError(
+            "Retained page addresses need reconciliation before replacing content"
+        )
     return tree, space_slug
 
 
@@ -97,6 +101,22 @@ def import_space_tree(
     tree: Path, *, tenant_id: str, slug: str | None = None,
     member: Member | None = None, title: str | None = None,
     replace: bool = False, memberships: list[tuple[Member, str]] | None = None,
+) -> ImportReport:
+    # Invalid proposals remain write-free, including lock-file creation.
+    validate_space_tree(tree, tenant_id=tenant_id, slug=slug, member=member,
+                        replace=replace, title=title)
+    for mapped, role in memberships or []:
+        if mapped.tenant_id != tenant_id or role not in SpaceMembership.Role.values:
+            raise pageops.PageOpsError("Invalid membership tenant or role")
+    return _import_space_tree(tree, tenant_id=tenant_id, slug=slug, member=member,
+                              title=title, replace=replace, memberships=memberships)
+
+
+@pageops.content_writer
+def _import_space_tree(
+    tree: Path, *, tenant_id: str, slug: str | None = None,
+    member: Member | None = None, title: str | None = None,
+    replace: bool = False, memberships: list[tuple[Member, str]] | None = None,
 ) -> ImportReport:
     """Stage content, then publish with DB writes; restore on ordinary errors.
 
diff --git a/coulomb_social/apps/spaces/models.py b/coulomb_social/apps/spaces/models.py
index f3ec814..7196334 100644
--- a/coulomb_social/apps/spaces/models.py
+++ b/coulomb_social/apps/spaces/models.py
@@ -84,6 +84,13 @@ class Space(models.Model):
     def __str__(self) -> str:
         return f"{self.title} ({self.slug})@{self.tenant_id}"
 
+    def clean(self):
+        super().clean()
+        if Space.objects.filter(slug=self.slug).exclude(pk=self.pk).exists():
+            raise ValidationError({"slug": "This content instance already uses that slug"})
+        if self.created_by_id and self.created_by.tenant_id != self.tenant_id:
+            raise ValidationError({"created_by": "Creator belongs to another tenant"})
+
     @property
     def has_content_binding(self) -> bool:
         return bool(self.forgejo_owner and self.forgejo_repo)
@@ -103,7 +110,7 @@ class Space(models.Model):
 
 
 class SpaceMembership(models.Model):
-    """Optional explicit membership; v1 list also allows tenant-wide visibility."""
+    """Explicit tenant-matched access; ungranted tenant members cannot read."""
 
     class Role(models.TextChoices):
         OWNER = "owner", "Owner"
@@ -130,3 +137,8 @@ class SpaceMembership(models.Model):
 
     def __str__(self) -> str:
         return f"{self.member_id}@{self.space.slug}:{self.role}"
+
+    def clean(self):
+        super().clean()
+        if self.space_id and self.member_id and self.space.tenant_id != self.member.tenant_id:
+            raise ValidationError({"member": "Member belongs to another tenant"})
diff --git a/coulomb_social/apps/spaces/pageops.py b/coulomb_social/apps/spaces/pageops.py
index 8692cf9..7e1ca6c 100644
--- a/coulomb_social/apps/spaces/pageops.py
+++ b/coulomb_social/apps/spaces/pageops.py
@@ -12,12 +12,20 @@ The app DB holds Space rows as an index; bodies live on disk.
 
 from __future__ import annotations
 
+import fcntl
+import hashlib
 import json
 import logging
+import os
 import re
 import shutil
+import tempfile
+import threading
+from contextlib import contextmanager
 from dataclasses import dataclass, field
+from functools import wraps
 from pathlib import Path
+from urllib.parse import quote, unquote, urlsplit
 
 from django.conf import settings
 from django.utils.text import slugify as django_slugify
@@ -25,6 +33,67 @@ from django.utils.text import slugify as django_slugify
 logger = logging.getLogger(__name__)
 
 _SLUG_RE = re.compile(r"^[a-z0-9]+(?:-[a-z0-9]+)*$")
+_WRITER_LOCK = threading.RLock()
+_WRITER_STATE = threading.local()
+
+
+@contextmanager
+def content_write_lock():
+    """Serialize cooperating app/import workers on one mounted content instance."""
+    with _WRITER_LOCK:
+        if getattr(_WRITER_STATE, "active", False):
+            yield
+            return
+        root = content_root()
+        root.mkdir(parents=True, exist_ok=True)
+        fd = os.open(root / ".writer.lock", os.O_CREAT | os.O_RDWR | os.O_NOFOLLOW, 0o600)
+        try:
+            fcntl.flock(fd, fcntl.LOCK_EX)
+            _WRITER_STATE.active = True
+            yield
+        finally:
+            _WRITER_STATE.active = False
+            os.close(fd)
+
+
+def content_writer(function):
+    @wraps(function)
+    def locked(*args, **kwargs):
+        with content_write_lock():
+            return function(*args, **kwargs)
+    return locked
+
+
+def _fsync_directory(path):
+    fd = os.open(path, os.O_RDONLY | os.O_DIRECTORY | os.O_NOFOLLOW)
+    try:
+        os.fsync(fd)
+    finally:
+        os.close(fd)
+
+
+def _remember(space_slug, page_slug, data):
+    """Immutable content-addressed versions are part of the paired content backup."""
+    directory = content_root() / ".revisions" / space_slug / page_slug
+    directory.mkdir(parents=True, exist_ok=True)
+    digest = hashlib.sha256(data).hexdigest()
+    path = directory / f"{digest}.md"
+    if path.exists():
+        if path.read_bytes() != data:
+            raise PageOpsError("Stored revision integrity check failed")
+        return
+    temporary = None
+    try:
+        with tempfile.NamedTemporaryFile(dir=directory, delete=False) as stream:
+            temporary = Path(stream.name)
+            stream.write(data)
+            stream.flush()
+            os.fsync(stream.fileno())
+        os.replace(temporary, path)
+        _fsync_directory(directory)
+    finally:
+        if temporary is not None:
+            temporary.unlink(missing_ok=True)
 
 
 class PageOpsError(Exception):
@@ -42,6 +111,7 @@ class PageDoc:
     body: str = ""
     meta: dict = field(default_factory=dict)
     path: str = ""
+    revision: str = ""
 
     @property
     def exists(self) -> bool:
@@ -58,6 +128,8 @@ def content_root() -> Path:
 
 
 def space_dir(space_slug: str) -> Path:
+    if not _SLUG_RE.fullmatch(space_slug):
+        raise PageOpsError("Invalid space slug")
     return content_root() / "spaces" / space_slug
 
 
@@ -70,8 +142,15 @@ def assets_dir(space_slug: str) -> Path:
 
 
 def page_file(space_slug: str, page_slug: str) -> Path:
+    if not _SLUG_RE.fullmatch(page_slug):
+        raise PageOpsError("Invalid page slug")
     name = "index.md" if page_slug == "index" else f"{page_slug}.md"
-    return pages_dir(space_slug) / name
+    path = pages_dir(space_slug) / name
+    for component in (content_root() / "spaces", space_dir(space_slug),
+                      pages_dir(space_slug), path):
+        if component.is_symlink():
+            raise PageOpsError("Content paths must not be symlinks")
+    return path
 
 
 def normalize_slug(value: str, *, allow_index: bool = True) -> str:
@@ -123,6 +202,7 @@ def parse_frontmatter(text: str) -> tuple[dict, str]:
 
 
 def dump_frontmatter(meta: dict, body: str) -> str:
+    body = body.replace("\r\n", "\n").replace("\r", "\n")
     lines = ["---"]
     for key, value in meta.items():
         if value is None or value == "":
@@ -141,11 +221,59 @@ def dump_frontmatter(meta: dict, body: str) -> str:
 
 def ensure_space_tree(space_slug: str) -> Path:
     root = space_dir(space_slug)
+    page_file(space_slug, "index")
+    if assets_dir(space_slug).is_symlink():
+        raise PageOpsError("Content paths must not be symlinks")
     pages_dir(space_slug).mkdir(parents=True, exist_ok=True)
     assets_dir(space_slug).mkdir(parents=True, exist_ok=True)
     return root
 
 
+def page_aliases(space_slug):
+    page_file(space_slug, "index")  # Validate the trusted tree boundaries.
+    path = space_dir(space_slug) / ".page-aliases.json"
+    if path.is_symlink():
+        raise PageOpsError("Content paths must not be symlinks")
+    if not path.exists():
+        return {}
+    try:
+        aliases = json.loads(path.read_text(encoding="utf-8"))
+        if not isinstance(aliases, dict):
+            raise ValueError
+        for source, target in aliases.items():
+            if (not _SLUG_RE.fullmatch(source) or not isinstance(target, list)
+                    or len(target) != 2 or not all(
+                        isinstance(part, str) and _SLUG_RE.fullmatch(part) for part in target
+                    )):
+                raise ValueError
+        return aliases
+    except (ValueError, TypeError) as exc:
+        raise PageOpsError("Page-address history needs operator review") from exc
+
+
+@content_writer
+def remember_page_address(source_space, source_page, dest_space, dest_page):
+    source_page = normalize_slug(source_page)
+    dest_page = normalize_slug(dest_page)
+    space_dir(dest_space)
+    aliases = page_aliases(source_space)
+    aliases[source_page] = [dest_space, dest_page]
+    directory = space_dir(source_space)
+    temporary = None
+    try:
+        with tempfile.NamedTemporaryFile(dir=directory, delete=False) as stream:
+            temporary = Path(stream.name)
+            stream.write((json.dumps(aliases, sort_keys=True) + "\n").encode("utf-8"))
+            stream.flush()
+            os.fsync(stream.fileno())
+        os.replace(temporary, directory / ".page-aliases.json")
+        _fsync_directory(directory)
+    finally:
+        if temporary is not None:
+            temporary.unlink(missing_ok=True)
+
+
+@content_writer
 def write_page(
     space_slug: str,
     page_slug: str,
@@ -155,6 +283,7 @@ def write_page(
     visual: str = "",
     body: str = "",
     extra_meta: dict | None = None,
+    expected_revision: str | None = None,
 ) -> PageDoc:
     page_slug = normalize_slug(page_slug) if page_slug != "index" else "index"
     ensure_space_tree(space_slug)
@@ -167,7 +296,29 @@ def write_page(
     if extra_meta:
         meta.update(extra_meta)
     path = page_file(space_slug, page_slug)
-    path.write_text(dump_frontmatter(meta, body or ""), encoding="utf-8")
+    exists = path.is_file()
+    current = path.read_bytes() if exists else b""
+    if not exists and page_slug in page_aliases(space_slug):
+        raise PageOpsError("This page address is reserved by a renamed or moved page")
+    revision = hashlib.sha256(current).hexdigest() if exists else ""
+    if expected_revision is not None and expected_revision != revision:
+        raise PageOpsError("This page changed. Reopen it and merge your edits before saving")
+    data = dump_frontmatter(meta, body or "").encode("utf-8")
+    if exists:
+        _remember(space_slug, page_slug, current)
+    _remember(space_slug, page_slug, data)
+    temporary = None
+    try:
+        with tempfile.NamedTemporaryFile(dir=path.parent, delete=False) as stream:
+            temporary = Path(stream.name)
+            stream.write(data)
+            stream.flush()
+            os.fsync(stream.fileno())
+        os.replace(temporary, path)
+        _fsync_directory(path.parent)
+    finally:
+        if temporary is not None:
+            temporary.unlink(missing_ok=True)
     return read_page(space_slug, page_slug)
 
 
@@ -176,7 +327,8 @@ def read_page(space_slug: str, page_slug: str) -> PageDoc:
     path = page_file(space_slug, page_slug)
     if not path.is_file():
         return PageDoc(slug=page_slug, path="")
-    text = path.read_text(encoding="utf-8")
+    data = path.read_bytes()
+    text = data.decode("utf-8").replace("\r\n", "\n").replace("\r", "\n")
     meta, body = parse_frontmatter(text)
     return PageDoc(
         slug=page_slug,
@@ -186,6 +338,7 @@ def read_page(space_slug: str, page_slug: str) -> PageDoc:
         body=body,
         meta=meta,
         path=str(path),
+        revision=hashlib.sha256(data).hexdigest(),
     )
 
 
@@ -202,14 +355,81 @@ def list_pages(space_slug: str) -> list[PageDoc]:
     return docs
 
 
+@content_writer
 def delete_page(space_slug: str, page_slug: str) -> None:
     if page_slug == "index":
         raise PageOpsError("Cannot delete the space index page")
     path = page_file(space_slug, normalize_slug(page_slug))
     if path.is_file():
+        _remember(space_slug, page_slug, path.read_bytes())
         path.unlink()
+        _fsync_directory(path.parent)
 
 
+_BODY_ASSET = re.compile(
+    r"(?P<prefix>\]\(\s*<?|\]:\s*<?)(?P<url>(?:\.\./|\./)?assets/[^\s)>]+)"
+)
+
+
+def _copy_assets(source_space, dest_space, dest_page, visual, body):
+    """Copy local Visual and Markdown link/image destinations as one staged set."""
+    from .assets import asset_parts, open_local_asset
+
+    copied = {}
+    created = []
+
+    def copy_reference(reference, *, optional=False):
+        parsed = urlsplit(reference)
+        path = unquote(parsed.path)
+        for prefix in ("../assets/", "./assets/", "assets/"):
+            if path.startswith(prefix):
+                path = path[len(prefix):]
+                break
+        else:
+            raise PageOpsError("Local attachments must be inside the source space assets")
+        try:
+            parts = asset_parts(path)
+            if path not in copied:
+                try:
+                    source_file = open_local_asset(source_space, path)
+                except FileNotFoundError:
+                    if optional:
+                        return reference
+                    raise
+                # Include the relative-path hash to distinguish nested equal filenames.
+                suffix = (
+                    "" if len(parts) == 1 else f"-{hashlib.sha256(path.encode()).hexdigest()[:12]}"
+                )
+                dest_name = f"{dest_page}{suffix}-{parts[-1]}"
+                with source_file:
+                    with open_local_asset(dest_space, dest_name, create=True) as stream:
+                        created.append(assets_dir(dest_space) / dest_name)
+                        shutil.copyfileobj(source_file, stream)
+                        stream.flush()
+                        os.fsync(stream.fileno())
+                copied[path] = f"assets/{quote(dest_name)}"
+            suffix = (f"?{parsed.query}" if parsed.query else "")
+            suffix += f"#{parsed.fragment}" if parsed.fragment else ""
+            return copied[path] + suffix
+        except (OSError, ValueError) as exc:
+            raise PageOpsError(
+                "Cannot copy the destination Visual or body attachment safely"
+            ) from exc
+
+    try:
+        if visual and not visual.startswith(("http", "/")):
+            visual = copy_reference(visual, optional=True)
+        body = _BODY_ASSET.sub(
+            lambda match: match["prefix"] + copy_reference(match["url"]), body,
+        )
+        return visual, body, created
+    except BaseException:
+        for path in created:
+            path.unlink(missing_ok=True)
+        raise
+
+
+@content_writer
 def copy_page(
     source_space: str,
     source_page: str,
@@ -222,76 +442,49 @@ def copy_page(
     if not src.exists:
         raise PageOpsError("Source page not found")
     dest_page = normalize_slug(dest_page)
-    if page_file(dest_space, dest_page).is_file():
+    if (page_file(dest_space, dest_page).is_file()
+            or dest_page in page_aliases(dest_space)):
         raise PageOpsError("Destination page already exists")
     ensure_space_tree(dest_space)
-    # copy visual asset if relative
-    visual = src.visual
-    if visual and not visual.startswith("http") and not visual.startswith("/"):
-        from .assets import open_local_asset
-
-        if not visual.startswith("assets/"):
-            raise PageOpsError("Visual must be inside the source space assets")
-        try:
-            source_file = open_local_asset(source_space, visual[len("assets/"):])
-        except FileNotFoundError:
-            source_file = None
-        except (OSError, ValueError) as exc:
-            raise PageOpsError("Cannot copy this Visual safely") from exc
-        if source_file is not None:
-            dest_name = f"{dest_page}-{Path(visual).name}"
-            with source_file:
-                try:
-                    with open_local_asset(dest_space, dest_name, create=True) as destination_file:
-                        shutil.copyfileobj(source_file, destination_file)
-                except OSError as exc:
-                    raise PageOpsError("Cannot write the destination Visual safely") from exc
-            visual = f"assets/{dest_name}"
-    new_title = title if title is not None else (src.title or dest_page)
-    if new_title == src.title and source_space == dest_space:
-        new_title = f"{src.title} (copy)" if src.title else f"{dest_page}"
-    return write_page(
-        dest_space,
-        dest_page,
-        title=new_title,
-        abstractor=src.abstractor,
-        visual=visual,
-        body=src.body,
-        extra_meta={
-            k: v for k, v in src.meta.items()
-            if k not in {"title", "abstractor", "visual", "space"}
-        },
+    visual, body, created = _copy_assets(
+        source_space, dest_space, dest_page, src.visual, src.body,
     )
+    new_title = title if title is not None else (src.title or dest_page)
+    if title is None and new_title == src.title and source_space == dest_space:
+        new_title = f"{src.title} (copy)" if src.title else f"{dest_page}"
+    try:
+        return write_page(
+            dest_space, dest_page, title=new_title, abstractor=src.abstractor,
+            visual=visual, body=body, expected_revision="",
+            extra_meta={k: v for k, v in src.meta.items()
+                        if k not in {"title", "abstractor", "visual", "space"}},
+        )
+    except BaseException:
+        if not page_file(dest_space, dest_page).exists():
+            for path in created:
+                path.unlink(missing_ok=True)
+        raise
 
 
+@content_writer
 def transfer_page(
     source_space: str,
     source_page: str,
     dest_space: str,
     dest_page: str | None = None,
 ) -> PageDoc:
-    dest_page = dest_page or source_page
+    source_page = normalize_slug(source_page)
+    dest_page = normalize_slug(dest_page or source_page)
     if source_page == "index":
         raise PageOpsError("Cannot transfer the space index page")
-    doc = copy_page(source_space, source_page, dest_space, dest_page, title=None)
-    # restore original title (copy_page may suffix)
     src = read_page(source_space, source_page)
-    write_page(
-        dest_space,
-        dest_page,
-        title=src.title,
-        abstractor=src.abstractor,
-        visual=doc.visual,
-        body=src.body,
-        extra_meta={
-            k: v for k, v in src.meta.items()
-            if k not in {"title", "abstractor", "visual", "space"}
-        },
-    )
+    copy_page(source_space, source_page, dest_space, dest_page, title=src.title)
+    remember_page_address(source_space, source_page, dest_space, dest_page)
     delete_page(source_space, source_page)
     return read_page(dest_space, dest_page)
 
 
+@content_writer
 def init_space_content(
     space_slug: str,
     *,
@@ -313,6 +506,7 @@ def init_space_content(
     )
 
 
+@content_writer
 def rename_space_tree(old_slug: str, new_slug: str) -> None:
     old = space_dir(old_slug)
     new = space_dir(new_slug)
@@ -324,6 +518,7 @@ def rename_space_tree(old_slug: str, new_slug: str) -> None:
     old.rename(new)
 
 
+@content_writer
 def archive_space_tree(space_slug: str) -> None:
     """Soft-archive: rename tree to .archived-<slug> if present."""
     root = space_dir(space_slug)
@@ -331,7 +526,7 @@ def archive_space_tree(space_slug: str) -> None:
         return
     dest = content_root() / "spaces" / f".archived-{space_slug}"
     if dest.exists():
-        shutil.rmtree(dest)
+        raise PageOpsError("A retained archive already exists; resolve it before archiving again")
     root.rename(dest)
 
 
diff --git a/coulomb_social/apps/spaces/services.py b/coulomb_social/apps/spaces/services.py
index da39ea6..849fd4b 100644
--- a/coulomb_social/apps/spaces/services.py
+++ b/coulomb_social/apps/spaces/services.py
@@ -2,8 +2,9 @@
 
 from __future__ import annotations
 
+from django.core.exceptions import ValidationError
 from django.db import transaction
-from django.db.models import Q, QuerySet
+from django.db.models import Count, Q, QuerySet
 
 from coulomb_social.apps.members.models import Member
 
@@ -16,7 +17,10 @@ def spaces_for_member(member: Member | None) -> QuerySet[Space]:
     if member is None:
         return Space.objects.none()
 
-    qs = Space.objects.filter(tenant_id=member.tenant_id, is_active=True)
+    ambiguous = Space.objects.values("slug").annotate(n=Count("pk")).filter(n__gt=1)
+    qs = Space.objects.filter(tenant_id=member.tenant_id, is_active=True).exclude(
+        slug__in=ambiguous.values("slug")
+    )
     return (
         qs.filter(Q(memberships__member=member) | Q(created_by=member))
         .distinct()
@@ -34,17 +38,61 @@ def can_write_space(member: Member | None, space: Space) -> bool:
     """Require an exact tenant/space grant, not a same-slug visibility match."""
     if member is None or member.tenant_id != space.tenant_id or not space.is_active:
         return False
+    if Space.objects.filter(slug=space.slug).exclude(pk=space.pk).exists():
+        return False
     membership = SpaceMembership.objects.filter(space=space, member=member).first()
     if membership is not None:
         return membership.role in {SpaceMembership.Role.OWNER, SpaceMembership.Role.MEMBER}
     return space.created_by_id == member.pk
 
 
+def can_manage_space(member: Member | None, space: Space) -> bool:
+    if not can_write_space(member, space):
+        return False
+    grant = SpaceMembership.objects.filter(space=space, member=member).first()
+    return grant.role == SpaceMembership.Role.OWNER if grant else space.created_by_id == member.pk
+
+
+@transaction.atomic
+def set_space_access(member: Member, space: Space, target_id, role: str) -> None:
+    """Owners grant access to an existing, exact local member; never invite by email."""
+    space = Space.objects.select_for_update().get(pk=space.pk)
+    if not can_manage_space(member, space):
+        raise pageops.PageOpsError("Only a space owner can manage sharing")
+    try:
+        target = Member.objects.select_for_update().get(pk=target_id, tenant_id=space.tenant_id)
+    except (Member.DoesNotExist, ValidationError, ValueError, TypeError):
+        raise pageops.PageOpsError("Choose an existing member in this tenant") from None
+    if role not in {*SpaceMembership.Role.values, "remove"}:
+        raise pageops.PageOpsError("Choose a valid access role")
+    # A creator has an implicit grant. Do not claim to revoke that grant by
+    # deleting a membership that would simply re-enable the fallback.
+    if target.pk == space.created_by_id and role != SpaceMembership.Role.OWNER:
+        raise pageops.PageOpsError("The creator must retain owner access")
+    current = SpaceMembership.objects.filter(space=space, member=target).first()
+    if current and current.role == "owner" and role != "owner":
+        others = SpaceMembership.objects.filter(
+            space=space, role="owner", member__tenant_id=space.tenant_id,
+        ).exclude(member=target)
+        if not others.exists() and not (
+            space.created_by_id and space.created_by_id != target.pk
+            and space.created_by.tenant_id == space.tenant_id
+        ):
+            raise pageops.PageOpsError("Keep at least one owner")
+    if role == "remove":
+        SpaceMembership.objects.filter(space=space, member=target).delete()
+    else:
+        SpaceMembership.objects.update_or_create(
+            space=space, member=target, defaults={"role": role},
+        )
+
+
 def require_space_write(member: Member | None, space: Space) -> None:
     if not can_write_space(member, space):
         raise pageops.PageOpsError("You have read-only access to this space")
 
 
+@pageops.content_writer
 @transaction.atomic
 def create_space(
     member: Member,
@@ -54,6 +102,8 @@ def create_space(
     slug: str | None = None,
     visual: str = "",
 ) -> Space:
+    if member is None:
+        raise pageops.PageOpsError("Sign in with a local member profile before creating a space")
     title = (title or "").strip()
     if not title:
         raise pageops.PageOpsError("Title is required")
@@ -85,6 +135,7 @@ def create_space(
     return space
 
 
+@pageops.content_writer
 @transaction.atomic
 def update_space(
     member: Member,
@@ -93,8 +144,14 @@ def update_space(
     title: str | None = None,
     abstractor: str | None = None,
     visual: str | None = None,
+    expected_revision: str | None = None,
 ) -> Space:
     require_space_write(member, space)
+    index = pageops.read_page(space.slug, "index")
+    if expected_revision is not None and index.revision != expected_revision:
+        raise pageops.PageOpsError(
+            "This space changed. Reopen it and merge your edits before saving"
+        )
     if title is not None:
         space.title = title.strip() or space.title
     if abstractor is not None:
@@ -103,7 +160,6 @@ def update_space(
         space.visual = visual
     space.save()
     # Keep index.md in sync
-    index = pageops.read_page(space.slug, "index")
     body = index.body if index.exists else f"# {space.title}\n"
     pageops.write_page(
         space.slug,
@@ -112,21 +168,21 @@ def update_space(
         abstractor=space.description,
         visual=space.visual,
         body=body,
-        extra_meta={"bubble_type": "space"},
+        extra_meta={**{k: v for k, v in index.meta.items()
+                      if k not in {"title", "abstractor", "visual", "space"}},
+                    "bubble_type": "space"},
+        expected_revision=expected_revision,
     )
     return space
 
 
+@pageops.content_writer
 @transaction.atomic
 def archive_space(member: Member, space: Space) -> Space:
     require_space_write(member, space)
     space.is_active = False
     space.save(update_fields=["is_active", "updated_at"])
-    try:
-        pageops.archive_space_tree(space.slug)
-    except Exception:
-        # Tree archive is best-effort
-        pass
+    pageops.archive_space_tree(space.slug)
     return space
 
 
@@ -134,6 +190,7 @@ def list_space_pages(space: Space) -> list[pageops.PageDoc]:
     return pageops.list_pages(space.slug)
 
 
+@pageops.content_writer
 def put_space_page(
     member: Member,
     space: Space,
@@ -144,6 +201,7 @@ def put_space_page(
     visual: str = "",
     body: str = "",
     extra_meta: dict | None = None,
+    expected_revision: str | None = None,
 ) -> pageops.PageDoc:
     require_space_write(member, space)
     metadata = (pageops.read_page(space.slug, page_slug).meta
@@ -157,6 +215,7 @@ def put_space_page(
         body=body,
         extra_meta={k: v for k, v in metadata.items()
                     if k not in {"title", "abstractor", "visual", "space"}},
+        expected_revision=expected_revision,
     )
 
 
@@ -181,6 +240,27 @@ def copy_space_page(
     )
 
 
+@pageops.content_writer
+def save_space_page(member, space, source_slug, target_slug, *, expected_revision, **fields):
+    require_space_write(member, space)
+    source = pageops.read_page(space.slug, source_slug)
+    if expected_revision is None or source.revision != expected_revision:
+        raise pageops.PageOpsError(
+            "This page changed. Reopen it and merge your edits before saving"
+        )
+    if source_slug == "index" and target_slug != "index":
+        raise pageops.PageOpsError("The space index file is fixed")
+    if target_slug != source_slug and pageops.page_file(space.slug, target_slug).exists():
+        raise pageops.PageOpsError("A page with that slug already exists")
+    doc = put_space_page(member, space, target_slug, extra_meta=source.meta,
+                         expected_revision=expected_revision if source_slug == target_slug else "",
+                         **fields)
+    if source_slug != target_slug:
+        pageops.remember_page_address(space.slug, source_slug, space.slug, target_slug)
+        pageops.delete_page(space.slug, source_slug)
+    return doc
+
+
 def transfer_space_page(
     member: Member,
     space: Space,
diff --git a/coulomb_social/apps/spaces/urls.py b/coulomb_social/apps/spaces/urls.py
index 1240df3..41991f2 100644
--- a/coulomb_social/apps/spaces/urls.py
+++ b/coulomb_social/apps/spaces/urls.py
@@ -13,6 +13,7 @@ urlpatterns = [
     path("new/", views.space_create, name="create"),
     path("<slug:slug>/assets/<path:asset_path>", views.space_asset, name="asset"),
     path("<slug:slug>/edit/", views.space_edit, name="edit"),
+    path("<slug:slug>/sharing/", views.space_sharing, name="sharing"),
     path("<slug:slug>/archive/", views.space_archive, name="archive"),
     path("<slug:slug>/refresh/", views.space_refresh, name="refresh"),
     path("<slug:slug>/pages/new/", views.page_new, name="page_new"),
diff --git a/coulomb_social/apps/spaces/views.py b/coulomb_social/apps/spaces/views.py
index 7990bb4..2f2056a 100644
--- a/coulomb_social/apps/spaces/views.py
+++ b/coulomb_social/apps/spaces/views.py
@@ -31,15 +31,18 @@ from .content import (
     forgejo_repo_url,
     load_space_page,
 )
-from .models import Space
+from .models import Space, SpaceMembership
 from .services import (
     archive_space,
+    can_manage_space,
     can_write_space,
     copy_space_page,
     create_space,
     get_space_for_member,
     list_space_pages,
     put_space_page,
+    save_space_page,
+    set_space_access,
     spaces_for_member,
     transfer_space_page,
     update_space,
@@ -48,6 +51,12 @@ from .services import (
 logger = logging.getLogger(__name__)
 
 
+def _mutation_error(exc):
+    if isinstance(exc, pageops.PageOpsError):
+        return exc.message
+    return "The content write could not be confirmed. Reopen the page before retrying."
+
+
 @login_required
 @require_safe
 def space_asset(request: HttpRequest, slug: str, asset_path: str) -> HttpResponse:
@@ -101,8 +110,8 @@ def space_create(request: HttpRequest) -> HttpResponse:
             )
             messages.success(request, f"Space “{space.title}” created.")
             return redirect("spaces:detail", slug=space.slug)
-        except pageops.PageOpsError as exc:
-            messages.error(request, exc.message)
+        except (pageops.PageOpsError, OSError) as exc:
+            messages.error(request, _mutation_error(exc))
     return render(
         request,
         "spaces/form.html",
@@ -130,17 +139,23 @@ def space_edit(request: HttpRequest, slug: str) -> HttpResponse:
         return HttpResponseForbidden("You have read-only access to this space.")
     if request.method == "POST":
         try:
+            if "revision" not in request.POST:
+                raise pageops.PageOpsError("Reopen this space before saving")
             update_space(
                 member,
                 space,
                 title=(request.POST.get("title") or "").strip(),
                 abstractor=(request.POST.get("abstractor") or "").strip(),
                 visual=(request.POST.get("visual") or "").strip(),
+                expected_revision=request.POST.get("revision"),
             )
             messages.success(request, "Space updated.")
             return redirect("spaces:detail", slug=space.slug)
-        except pageops.PageOpsError as exc:
-            messages.error(request, exc.message)
+        except (pageops.PageOpsError, OSError) as exc:
+            messages.error(request, _mutation_error(exc))
+            space.title = request.POST.get("title", space.title)
+            space.description = request.POST.get("abstractor", space.description)
+            space.visual = request.POST.get("visual", space.visual)
     return render(
         request,
         "spaces/form.html",
@@ -150,6 +165,8 @@ def space_edit(request: HttpRequest, slug: str) -> HttpResponse:
             "form_title": f"Edit {space.title}",
             "space": space,
             "submit_label": "Save",
+            "revision": (request.POST.get("revision", "") if request.method == "POST"
+                         else pageops.read_page(space.slug, "index").revision),
         },
     )
 
@@ -169,8 +186,8 @@ def space_archive(request: HttpRequest, slug: str) -> HttpResponse:
     try:
         archive_space(member, space)
         messages.success(request, f"Space “{space.title}” archived.")
-    except pageops.PageOpsError as exc:
-        messages.error(request, exc.message)
+    except (pageops.PageOpsError, OSError) as exc:
+        messages.error(request, _mutation_error(exc))
     return redirect("core:app_home")
 
 
@@ -185,6 +202,33 @@ def space_detail(request: HttpRequest, slug: str) -> HttpResponse:
         return HttpResponseNotFound("Space not found.")
 
     page = request.GET.get("page") or "index"
+    # Old incoming links survive rename/move, but every hop still requires an
+    # active exact tenant/space grant. Never redirect an unauthorized reader.
+    try:
+        page = pageops.normalize_slug(page)
+        target_space, target_page = space, page
+        visited = set()
+        while not pageops.read_page(target_space.slug, target_page).exists:
+            key = (target_space.slug, target_page)
+            if key in visited or len(visited) >= 16:
+                return HttpResponseNotFound("Page not found.")
+            visited.add(key)
+            alias = pageops.page_aliases(target_space.slug).get(target_page)
+            if alias is None:
+                break
+            target_space = get_space_for_member(member, alias[0])
+            if target_space is None:
+                return HttpResponseNotFound("Page not found.")
+            target_page = alias[1]
+        if (target_space.pk, target_page) != (space.pk, page):
+            if not pageops.read_page(target_space.slug, target_page).exists:
+                return HttpResponseNotFound("Page not found.")
+            target = reverse("spaces:detail", kwargs={"slug": target_space.slug})
+            response = redirect(f"{target}?page={target_page}")
+            response["Cache-Control"] = "private, no-store"
+            return response
+    except pageops.PageOpsError:
+        return HttpResponseNotFound("Page not found.")
     rendered = load_space_page(space, page)
     pages = list_space_pages(space)
     return render(
@@ -198,6 +242,7 @@ def space_detail(request: HttpRequest, slug: str) -> HttpResponse:
             "space_visual_url": local_asset_url(space.slug, space.visual),
             "pages": pages,
             "can_write": can_write_space(member, space),
+            "can_manage": can_manage_space(member, space),
             "forgejo_repo_url": forgejo_repo_url(space),
             "forgejo_edit_url": forgejo_edit_url(space, page),
             "forgejo_blob_url": forgejo_blob_url(space, page),
@@ -205,6 +250,36 @@ def space_detail(request: HttpRequest, slug: str) -> HttpResponse:
     )
 
 
+@login_required
+@require_http_methods(["GET", "POST"])
+def space_sharing(request, slug):
+    principal, forbid = _principal_or_forbid(request, "space_sharing")
+    if forbid:
+        return forbid
+    member = principal.get("member")
+    space = get_space_for_member(member, slug)
+    if space is None:
+        return HttpResponseNotFound("Space not found.")
+    if not can_manage_space(member, space):
+        return HttpResponseForbidden("Only a space owner can manage sharing.")
+    if request.method == "POST":
+        try:
+            set_space_access(member, space, request.POST.get("member_id"),
+                             request.POST.get("role", ""))
+        except (pageops.PageOpsError, OSError) as exc:
+            messages.error(request, _mutation_error(exc))
+        else:
+            messages.success(request, "Space access updated.")
+            return redirect("spaces:sharing", slug=slug)
+    response = render(request, "spaces/sharing.html", {
+        "space": space, "roles": SpaceMembership.Role.choices,
+        "grants": space.memberships.filter(member__tenant_id=space.tenant_id)
+        .select_related("member"),
+    })
+    response["Cache-Control"] = "private, no-store"
+    return response
+
+
 @login_required
 @require_http_methods(["GET", "POST"])
 def page_edit(request: HttpRequest, slug: str, page_slug: str = "index") -> HttpResponse:
@@ -221,8 +296,8 @@ def page_edit(request: HttpRequest, slug: str, page_slug: str = "index") -> Http
     if page_slug != "index":
         try:
             page_slug = pageops.normalize_slug(page_slug)
-        except pageops.PageOpsError as exc:
-            messages.error(request, exc.message)
+        except (pageops.PageOpsError, OSError) as exc:
+            messages.error(request, _mutation_error(exc))
             return redirect("spaces:detail", slug=slug)
 
     doc = pageops.read_page(space.slug, page_slug)
@@ -237,41 +312,18 @@ def page_edit(request: HttpRequest, slug: str, page_slug: str = "index") -> Http
                 target_slug = "index"
             else:
                 target_slug = pageops.normalize_slug(new_slug)
-            if target_slug != page_slug and page_slug != "index":
-                # rename: write new, delete old
-                if pageops.page_file(space.slug, target_slug).is_file():
-                    raise pageops.PageOpsError("A page with that slug already exists")
-                put_space_page(
-                    member,
-                    space,
-                    target_slug,
-                    title=title,
-                    abstractor=abstractor,
-                    visual=visual,
-                    body=body,
-                    extra_meta=doc.meta,
-                )
-                pageops.delete_page(space.slug, page_slug)
-                page_slug = target_slug
-            else:
-                put_space_page(
-                    member,
-                    space,
-                    target_slug,
-                    title=title,
-                    abstractor=abstractor,
-                    visual=visual,
-                    body=body,
-                )
-                page_slug = target_slug
+            save_space_page(member, space, page_slug, target_slug,
+                            expected_revision=request.POST.get("revision"),
+                            title=title, abstractor=abstractor, visual=visual, body=body)
+            page_slug = target_slug
             clear_content_cache_for_space(space)
             messages.success(request, "Page saved.")
             target = reverse("spaces:detail", kwargs={"slug": space.slug})
             if page_slug != "index":
                 target = f"{target}?page={page_slug}"
             return redirect(target)
-        except pageops.PageOpsError as exc:
-            messages.error(request, exc.message)
+        except (pageops.PageOpsError, OSError) as exc:
+            messages.error(request, _mutation_error(exc))
             doc = pageops.PageDoc(
                 slug=page_slug,
                 title=title,
@@ -279,6 +331,7 @@ def page_edit(request: HttpRequest, slug: str, page_slug: str = "index") -> Http
                 visual=visual,
                 body=body,
                 path=doc.path,
+                revision=request.POST.get("revision", ""),
             )
 
     return render(
@@ -289,6 +342,7 @@ def page_edit(request: HttpRequest, slug: str, page_slug: str = "index") -> Http
             "display_name": principal["display_name"],
             "space": space,
             "doc": doc,
+            "submitted_slug": request.POST.get("slug", page_slug),
             "is_new": not doc.exists,
             "form_title": "Edit or rename page" if doc.exists else "New page",
         },
@@ -331,13 +385,14 @@ def page_new(request: HttpRequest, slug: str) -> HttpResponse:
                 abstractor=abstractor,
                 visual=visual,
                 body=body,
+                expected_revision="",
             )
             clear_content_cache_for_space(space)
             messages.success(request, "Page created.")
             target = reverse("spaces:detail", kwargs={"slug": space.slug})
             return redirect(f"{target}?page={page_slug}")
-        except pageops.PageOpsError as exc:
-            messages.error(request, exc.message)
+        except (pageops.PageOpsError, OSError) as exc:
+            messages.error(request, _mutation_error(exc))
 
     return render(
         request,
@@ -377,8 +432,8 @@ def page_delete(request: HttpRequest, slug: str, page_slug: str) -> HttpResponse
         pageops.delete_page(space.slug, page_slug)
         clear_content_cache_for_space(space)
         messages.success(request, f"Page “{page_slug}” deleted.")
-    except pageops.PageOpsError as exc:
-        messages.error(request, exc.message)
+    except (pageops.PageOpsError, OSError) as exc:
+        messages.error(request, _mutation_error(exc))
     return redirect("spaces:detail", slug=slug)
 
 
@@ -417,8 +472,8 @@ def page_copy(request: HttpRequest, slug: str, page_slug: str) -> HttpResponse:
             if doc.slug != "index":
                 target = f"{target}?page={doc.slug}"
             return redirect(target)
-        except pageops.PageOpsError as exc:
-            messages.error(request, exc.message)
+        except (pageops.PageOpsError, OSError) as exc:
+            messages.error(request, _mutation_error(exc))
     return render(
         request,
         "spaces/page_copy.html",
@@ -468,8 +523,8 @@ def page_transfer(request: HttpRequest, slug: str, page_slug: str) -> HttpRespon
             if doc.slug != "index":
                 target = f"{target}?page={doc.slug}"
             return redirect(target)
-        except pageops.PageOpsError as exc:
-            messages.error(request, exc.message)
+        except (pageops.PageOpsError, OSError) as exc:
+            messages.error(request, _mutation_error(exc))
     return render(
         request,
         "spaces/page_transfer.html",
diff --git a/coulomb_social/templates/base.html b/coulomb_social/templates/base.html
index 3794a7f..e34d7f0 100644
--- a/coulomb_social/templates/base.html
+++ b/coulomb_social/templates/base.html
@@ -154,6 +154,7 @@
           <div class="menu-panel" role="menu">
             <div class="menu-meta">Signed in</div>
             <a href="{% url 'core:account_session' %}" role="menuitem">Session details</a>
+            <a href="{% url 'core:account_data' %}" role="menuitem">Your app data</a>
             <a href="{% url 'identity:logout' %}" role="menuitem">Sign out</a>
           </div>
         </details>
diff --git a/coulomb_social/templates/core/account_data.html b/coulomb_social/templates/core/account_data.html
new file mode 100644
index 0000000..ce2e007
--- /dev/null
+++ b/coulomb_social/templates/core/account_data.html
@@ -0,0 +1,26 @@
+{% extends "base.html" %}
+{% block title %}Your app data — {{ site_name }}{% endblock %}
+{% block content %}
+<h1>Your app data</h1>
+<p>Your member ID: <code>{{ member.id }}</code>. Share this ID with a space owner to request access.</p>
+<p><a class="btn" href="{% url 'core:account_export' %}">Export my account records</a></p>
+<p>The export includes your local profile, identity references and memberships. Pages and assets remain in their spaces.</p>
+<h2>Leaving the app</h2>
+<p>Removing your local account removes its profile and space grants and signs you out.
+Shared pages and assets stay with their spaces. Existing backups follow the operator's retention policy.
+Your platform identity and mailbox remain active; signing in again creates a new local profile without your old grants.</p>
+<h2>Spaces you are responsible for</h2>
+<ul>{% for space in retained_spaces %}<li>{{ space.title }}{% if not space.is_active %} (archived){% endif %}</li>{% empty %}<li>None</li>{% endfor %}</ul>
+{% if ownership_review %}
+<p>An inconsistent ownership record needs operator review before removal.</p>
+{% elif blockers %}
+<p>Before removal, give another active member owner access to each of these spaces:</p>
+<ul>{% for space in blockers %}<li>{{ space.title }}</li>{% endfor %}</ul>
+{% else %}
+<form method="post">{% csrf_token %}
+<label for="confirmation">Type DELETE to remove your local account</label>
+<input id="confirmation" name="confirmation" type="text" required autocomplete="off">
+<button class="btn secondary" type="submit">Remove local account</button>
+</form>
+{% endif %}
+{% endblock %}
diff --git a/coulomb_social/templates/spaces/detail.html b/coulomb_social/templates/spaces/detail.html
index 79b2650..14f3571 100644
--- a/coulomb_social/templates/spaces/detail.html
+++ b/coulomb_social/templates/spaces/detail.html
@@ -97,6 +97,7 @@
     <div class="content-actions" style="margin:0;">
       <a class="btn secondary small" href="{% url 'spaces:edit' space.slug %}">Edit space</a>
       <a class="btn secondary small" href="{% url 'spaces:page_new' space.slug %}">New page</a>
+      {% if can_manage %}<a class="btn secondary small" href="{% url 'spaces:sharing' space.slug %}">Share space</a>{% endif %}
     </div>
     {% endif %}
   </div>
diff --git a/coulomb_social/templates/spaces/form.html b/coulomb_social/templates/spaces/form.html
index 4514353..0998383 100644
--- a/coulomb_social/templates/spaces/form.html
+++ b/coulomb_social/templates/spaces/form.html
@@ -34,6 +34,7 @@
 
   <form method="post" class="card" style="margin-top:1rem;">
     {% csrf_token %}
+    {% if space %}<input type="hidden" name="revision" value="{{ revision }}">{% endif %}
     <label for="id_title">Title</label>
     <input type="text" id="id_title" name="title" required maxlength="255"
            value="{% if space %}{{ space.title }}{% endif %}" autocomplete="off">
diff --git a/coulomb_social/templates/spaces/page_form.html b/coulomb_social/templates/spaces/page_form.html
index 43ccd26..349e8c5 100644
--- a/coulomb_social/templates/spaces/page_form.html
+++ b/coulomb_social/templates/spaces/page_form.html
@@ -34,6 +34,7 @@
 
   <form method="post" class="card" style="margin-top:1rem;">
     {% csrf_token %}
+    <input type="hidden" name="revision" value="{{ doc.revision }}">
     <label for="id_title">Title</label>
     <input type="text" id="id_title" name="title" maxlength="255"
            value="{{ doc.title }}" autocomplete="off"
@@ -44,7 +45,7 @@
       <input type="text" id="id_slug" name="slug" value="index" readonly maxlength="80">
     {% else %}
       <input type="text" id="id_slug" name="slug" maxlength="80"
-             value="{{ doc.slug }}"
+             value="{{ submitted_slug|default:doc.slug }}"
              pattern="[a-z0-9]+(?:-[a-z0-9]+)*"
              placeholder="page-slug" autocomplete="off"
              {% if is_new %}required{% endif %}>
diff --git a/coulomb_social/templates/spaces/sharing.html b/coulomb_social/templates/spaces/sharing.html
new file mode 100644
index 0000000..b9c5b6e
--- /dev/null
+++ b/coulomb_social/templates/spaces/sharing.html
@@ -0,0 +1,21 @@
+{% extends "base.html" %}
+{% block title %}Share {{ space.title }} — {{ site_name }}{% endblock %}
+{% block content %}
+<p><a href="{% url 'spaces:detail' space.slug %}">← {{ space.title }}</a></p>
+<h1>Share space</h1>
+<p>Ask the person for the member ID shown in Your app data. They must already have signed in to this tenant.
+Viewers can read and copy content. Members can edit. Owners can also manage sharing.
+Access covers every page and image in this space. This action does not send email.</p>
+<form method="post" class="card">{% csrf_token %}
+<label for="member_id">Member ID</label>
+<input id="member_id" name="member_id" type="text" required autocomplete="off">
+<label for="role">Access</label>
+<select id="role" name="role">
+{% for value, label in roles %}<option value="{{ value }}" {% if value == 'viewer' %}selected{% endif %}>{{ label }}</option>{% endfor %}
+<option value="remove">Remove access</option>
+</select>
+<p><button class="btn" type="submit">Update access</button></p>
+</form>
+<h2>Current access</h2>
+<ul>{% for grant in grants %}<li>{{ grant.member.display_name|default:grant.member.subject }} — {{ grant.get_role_display }} — <code>{{ grant.member_id }}</code></li>{% empty %}<li>The creator has owner access.</li>{% endfor %}</ul>
+{% endblock %}
diff --git a/docs/release/communication-regressions-2026-10-08.json b/docs/release/communication-regressions-2026-10-08.json
new file mode 100644
index 0000000..ba930e7
--- /dev/null
+++ b/docs/release/communication-regressions-2026-10-08.json
@@ -0,0 +1,36 @@
+{
+  "schema_version": 1,
+  "owner": "email-connect",
+  "passed": true,
+  "network": "all socket connects and DNS resolution denied",
+  "tests": 39,
+  "skipped": 0,
+  "failed": 0,
+  "missing_required_tests": [],
+  "source_sha256": {
+    "src/email_connect/__init__.py": "0f1ae5e9251f80b0bd5220b1d7bf91735d6ea273e07aa26cb7852a7950be7087",
+    "src/email_connect/adapter_contract.py": "5059b2eaaac2408f4e247bb468a97960eb3f823e63c3eeb151a1c2250e1f3bbf",
+    "src/email_connect/cli.py": "6ac6ae8acd091ba2d2102589be3b75fe3a48392309e40e61f8383deb3329ad42",
+    "src/email_connect/config.py": "6ca89fb7c3e1f35bc4faedfba8c3313d4366b2cb7830ef88ed3f7d2313f7867e",
+    "src/email_connect/evidence.py": "42cca03234a79dc78033ec1fbaf0b1785e6089ef3f3128e2e9d666ed239a3582",
+    "src/email_connect/mailbox.py": "7f0fe7e19ce1f814269609c4236152042f0f49bf3b517114b3b3f6f482471362",
+    "src/email_connect/models.py": "7f8136646b663a097280286dccce76a90abb7190ea0712fff7da32d47526521c",
+    "src/email_connect/parser.py": "786b291256ddfac5a8622c743622508cdd9f45f06156d0f5487ce399fad1287c",
+    "src/email_connect/recipients.py": "68792f44f0d2ba204649542aa8bd6b0f209d89c675baa4fc0767f1250a29045f",
+    "src/email_connect/reporting.py": "8f8ce5f98e4347b778893d08a9e58f2bab3b44b80c159fcf52d0b5772429737c",
+    "src/email_connect/scanner.py": "6266cbad2dbc610c1f6df1c051ded2ee55b43d7ff30af6eab38721924931c1ed",
+    "src/email_connect/storage.py": "57fbd6d3b2e7541c0bf52d87a4f7361a4ff4a03511620d2a1c3789632b73afeb",
+    "src/email_connect/transactional.py": "e917616911d11b00ec60d9ff129a7db804184051a24b8aa23d8809c8c2195cb2",
+    "tests/test_transactional.py": "7b443defb15b25427257045def348af0d7e5819c27659a52b7a53d78599301e6"
+  },
+  "contract_sha256": "7bcd65c29e572c0abbd3784e7ad1e8341f963aa12345c901f7946eac4e999c1d",
+  "acceptance_complete": false,
+  "remaining_acceptance": [
+    "CSOC-UC-009 isolated issuer reset, inbox and app browser journey",
+    "CSOC-UC-010/011 isolated registration and invitation browser journeys",
+    "Independent caller authentication, tenant/template scope, limits and scoped status",
+    "Platform sender and independent ledger backup custody admission",
+    "Named inbound/reply/bounce operations, alignment and retention",
+    "Per-flow productive user acceptance"
+  ]
+}
diff --git a/docs/release/sharing-portability-review-2026-10-08.md b/docs/release/sharing-portability-review-2026-10-08.md
new file mode 100644
index 0000000..e8ddca3
--- /dev/null
+++ b/docs/release/sharing-portability-review-2026-10-08.md
@@ -0,0 +1,118 @@
+# WP-0008 / WP-0010 implementation review — 2026-10-08
+
+This is a local source review. The current production release remains revision15;
+these changes have not been packaged or deployed. Both workplans remain active.
+Technical implementation decision: `9ffb5125-5551-4101-9025-5b6f72f40940`.
+
+## Product behavior now implemented
+
+Space owners can open **Share space**, enter an existing tenant member's ID and
+grant Viewer, Member or Owner access, or remove a grant. The member finds their
+ID under **Your app data**. No directory/email enumeration or notification send
+is involved. Viewers can read/copy content; members can write; only owners manage
+access. Creator access and the last owner cannot be revoked through this flow.
+Revocation denies subsequent page/image reads immediately.
+
+**Your app data** exports the requesting person's local profile, platform identity
+references, memberships and created-space metadata as a private JSON download.
+It excludes credentials, session tokens and other people's profiles. It does not
+export platform-owned account records or claim that shared pages belong to one
+person. Shared content is retained when a member leaves.
+
+The exit screen explains retained content/backups and lists ownership obligations,
+including archived spaces. Removal requires another active same-tenant owner for
+every retained space and typing DELETE. It clears creator attribution, deletes
+the app-local Member/User and their grants, and signs out; old sessions can no
+longer authenticate. NetKingdom/user-engine/mailbox identity remains separate.
+Signing in again creates a new local profile without the old grants. Corrupt
+cross-tenant creator links require operator review without disclosing foreign
+space titles. No live profile was removed while testing.
+
+## Storage, revision and link behavior
+
+The existing slug-keyed content layout is retained. App reads, lists and service
+writes fail closed on any duplicate slug, including inactive/foreign index rows.
+App creation/import and admin metadata saves serialize through the same mounted
+content writer lock; admin validation rejects global slug collisions and
+cross-tenant creator/grant links. Ordinary sharing cannot create a cross-tenant
+grant. Raw database/filesystem maintenance remains a paused-writer operation;
+this increment does not introduce a database-wide global slug constraint or
+tenant-directory migration. Production tenancy/cohort reconciliation stays T04.
+
+Cooperating threads/processes use a reentrant Python lock and Linux `flock` on
+`CONTENT_ROOT/.writer.lock`. App/import filesystem writes are serialized. Local
+account removal also takes that lock so new owned spaces cannot race its exit
+check. The existing one-instance persistent volume and paused-writer backup
+protocol remain required; this is not a distributed multi-node writer protocol.
+
+Page/space edit forms carry an exact byte-hash revision. A stale or missing
+revision preserves the submitted text and asks the writer to reopen/merge instead
+of overwriting another save. New-page/copy destination collisions also remain
+protected under the lock. Writes stage complete files, fsync, atomically replace
+the active file and fsync the directory. Browser CRLF is normalized to LF.
+Original imported metadata, including source identifiers, survives page rename
+and space-index edits.
+
+Exact previous/new Markdown versions live at
+`CONTENT_ROOT/.revisions/<space>/<page>/<sha256>.md`, including before deletion.
+They are private content-plane recovery material covered by the paired backup;
+they are not pushed to Forgejo. Retention/capacity admission and acceptance of
+this revision mechanism remain T02/T05 obligations. No automatic purge exists.
+An existing archived tree is retained rather than overwritten by a later archive.
+
+Copy/move stages local Visual and Markdown inline/reference-linked attachments,
+rewrites their destination URLs, distinguishes equal nested filenames and
+preserves query/fragment suffixes. Destination collisions, missing linked assets,
+traversal and symlinks refuse the operation; partial newly created assets are
+removed when publication fails. The source remains on failed destination writes.
+Uncertain completed writes preserve the destination for review. Product errors
+do not disclose private filesystem diagnostics. Raw HTML and arbitrary custom
+Markdown conventions still require corpus reconciliation.
+
+Rename/move retains `.page-aliases.json` in the original space. Old incoming page
+addresses resolve to the current page only after checking active exact grants at
+every hop, including both source and destination spaces. Old addresses cannot be
+reused for unrelated content. Denied destinations, loops and missing targets
+fail closed. Content replacement/import refuses retained aliases until their
+disposition is explicitly reconciled. Multi-file moves are not crash-atomic;
+paired recovery and attended maintenance remain the recovery protocol.
+
+## Communication regression implementation
+
+UC-009–012 are registered with synthetic fixtures and `established: false`.
+UC-009 preserves its recorded personal recovery acceptance; the other cases
+remain candidates. Empty browser bindings are explicit gaps rather than claimed
+end-to-end protection. UC-008's existing mandatory tests remain registered.
+
+`make check-communication EMAIL_CONNECT_ROOT=/path/to/email-connect` copies only
+owner Python source and its synthetic transactional test module to a private
+temporary directory. It strips inherited credentials, denies network connects
+and DNS, disables plugin autoload, and verifies 21 exact required test functions
+without skip/xfail. The original owner checkout remains untouched. A redacted
+receipt hashes the actual executed source/test/contract and reports results plus
+outstanding owner/user acceptance. No production account, provider or mailbox is
+used. See `communication-regressions-2026-10-08.json`.
+
+## Validation and remaining live gates
+
+`make check`: **182 passed**, repository-wide Ruff clean, both real Chromium
+journeys run. New cases cover sharing/revocation, personal export, CSRF, last-owner
+and archived-content retention, old-session denial, ambiguous storage, concurrent
+threads/processes, stale forms, blank imported pages, symlinks, linked attachments,
+incoming-address access and failed destination publication. Communication runner
+tests prove environment isolation, network denial and refused missing/disabled
+coverage. Owner gate: **39 passed, zero skips**. Django system check passes;
+`makemigrations --check --dry-run` finds no schema changes.
+
+WP-0008-T01/T02/T03/T04/T05/T06/T08/T09 remain open for the relevant pinned release,
+deployment/operational capacity, offsite custody/retention and recovery admission,
+actual corpus/tenancy/privacy reconciliation, service contract and productive
+per-journey user acceptance. Existing RPF-WP-0053 admission/activation handoffs
+remain the live backup dependency; no new offsite capture or timer is activated.
+
+WP-0010-T04/T05/T06 remain open for independent caller authentication, approved
+tenant/template limits and scoped status, platform sender custody, ledger backup
+admission (EMAIL-WP-0007-T03/T04 and RPF-WP-0053-T05), named reply/bounce ownership,
+inbound access/alignment/retention and isolated owner-spanning browser journeys.
+No external owner admission, new caller, email send, mailbox scan, runtime change,
+productive transfer acceptance or Bubble retirement is inferred from these tests.
diff --git a/docs/usecases/catalog.md b/docs/usecases/catalog.md
index 203bcc9..1470ee4 100644
--- a/docs/usecases/catalog.md
+++ b/docs/usecases/catalog.md
@@ -36,11 +36,11 @@ acceptance. Do not mark transfer accepted on the strength of tests alone.
 |---|---|---|---|---|
 | CSOC-UC-001 | Returning/new member signs in and reaches their work | Login/signup strings and historical identity evidence; original transfer journey inferred | OIDC + registration entry implemented; current cohort onboarding and live Case B need review | WP-0008-T01/T03; pending |
 | CSOC-UC-002 | Writer finds an existing space and opens a page to continue work | `vw_spaces`, `vw_pages`, space/page fields; inferred; one historical import rehearsal | Space/page navigation and markdown implemented; nominated real content, visuals, missing hierarchy and recognizability need review | T03/T05; pending |
-| CSOC-UC-003 | Writer creates and maintains a space/page with Title, Abstractor, Visual and body | Space/page create/edit symbols and captured card UI; inferred | Metadata/body forms implemented; Visual serving, safe content versioning and restart persistence outstanding | T01/T04/T05; pending |
-| CSOC-UC-004 | Writer makes an independent copy, or moves a page to another workspace | Copy icons captured; exact Bubble transfer action unresolved | Copy/move implemented; arbitrary assets/links and actual original semantics need comparison | T04/T05; pending |
-| CSOC-UC-005 | Reader sees shared work; outsider cannot access it; writer remains able to edit | Members/Guests/IsPrivate fields; original privacy rules inferred | First slice enforces viewer write denial and explicit membership/creator reads; membership management and exact Bubble privacy still outstanding | T04; pending |
-| CSOC-UC-006 | Member can take their app-local information with them or leave with a clear content outcome | Platform-contract portability need; Bubble equivalent **unknown** | Export/delete not implemented; ownership/retention UX requires definition | T04; pending |
-| CSOC-UC-007 | Member returns after a restart/incident and their work is still there | Continuity requirement, not a captured Bubble action | Persistent volume and paired DB/content restore evidence outstanding | T01/T02; pending |
+| CSOC-UC-003 | Writer creates and maintains a space/page with Title, Abstractor, Visual and body | Space/page create/edit symbols and captured card UI; inferred | Visuals are live; local revisions and stale-edit protection implemented; new release and revision/retention acceptance pending | T01/T04/T05; pending |
+| CSOC-UC-004 | Writer makes an independent copy, or moves a page to another workspace | Copy icons captured; exact Bubble transfer action unresolved | Local linked-attachment copy and guarded incoming-address preservation implemented; actual corpus/custom conventions and original semantics need comparison | T04/T05; pending |
+| CSOC-UC-005 | Reader sees shared work; outsider cannot access it; writer remains able to edit | Members/Guests/IsPrivate fields; original privacy rules inferred | Owner-managed same-tenant sharing/revocation, viewer denial and ambiguous-storage guards implemented locally; release, tenancy and original privacy review remain | T04; pending |
+| CSOC-UC-006 | Member can take their app-local information with them or leave with a clear content outcome | Platform-contract portability need; Bubble equivalent **unknown** | Local personal JSON export and reviewed exit screen implemented; shared content retained, successor owner required; deployment and productive user acceptance pending | T04; pending |
+| CSOC-UC-007 | Member returns after a restart/incident and their work is still there | Continuity requirement, not a captured Bubble action | Persistent storage and actual paired restore are evidenced; offsite custody/retention, monitoring and operational rollback remain | T01/T02; pending |
 | CSOC-UC-008 | Prepare the next ReichelAg founder call from the full previous protocol, write the new notes, copy them for manual email distribution | User-confirmed 2026-10-06; exact Bubble UI not freshly observed | Duplicate/edit implemented; clipboard action added; latest real protocol, mail-client paste and persistence review pending | T03/T05/T08/T09/T10; pending |
 
 ### Concrete scenario specification for the first review
@@ -64,7 +64,8 @@ edit the copy and confirm the source is independent; move another page and
 verify source removal, destination content and access.
 For UC-005: reader can open the shared page, sees read-only access and cannot
 change it by direct requests; outsider gets no content; destination write
-permission is checked before copy/move. Exact sharing UI remains part of T04.
+permission is checked before copy/move. Review the locally implemented Share
+space UI after its release; original privacy equivalence remains T04.
 For UC-006: compare the app-local export and proposed leaving behavior before
 confirming deletion; platform account handling is explicitly separate.
 For UC-007: compare the pre-incident content and access with an isolated restore.
diff --git a/docs/usecases/communication-regressions.json b/docs/usecases/communication-regressions.json
new file mode 100644
index 0000000..9f8afd4
--- /dev/null
+++ b/docs/usecases/communication-regressions.json
@@ -0,0 +1,36 @@
+{
+  "schema_version": 1,
+  "owner": "email-connect",
+  "test_file": "tests/test_transactional.py",
+  "required_tests": [
+    "test_rejects_auth_recipient_template_and_key",
+    "test_sends_fixed_template_once",
+    "test_resend_is_separate_event_and_sends_again",
+    "test_suppression_blocks_send",
+    "test_provider_timeout_temporary_and_permanent_are_redacted",
+    "test_status_authenticates_without_sending_and_redacts_errors",
+    "test_registration_verification_is_digest_only_and_single_use",
+    "test_registration_cancellation_is_single_use_and_prevents_verification",
+    "test_mailbox_evidence_is_not_authorization",
+    "test_lost_post_send_record_never_resends_after_restart",
+    "test_definitive_failure_retries_but_changed_payload_is_rejected",
+    "test_disconnect_after_smtp_acceptance_never_releases_reservation",
+    "test_verification_retry_after_restart_returns_same_receipt",
+    "test_verification_binding_cannot_change_on_retry",
+    "test_verification_uncertain_send_is_not_repeated_after_restart",
+    "test_verification_acceptance_record_failure_does_not_resend",
+    "test_verification_definitive_deferral_allows_retry_and_cancels_old_handle",
+    "test_verification_permanent_failure_stays_terminal",
+    "test_verification_concurrent_connections_reserve_before_provider_call",
+    "test_verification_tenant_and_client_operations_are_separate",
+    "test_legacy_verification_is_preserved_without_resending"
+  ],
+  "remaining_acceptance": [
+    "CSOC-UC-009 isolated issuer reset, inbox and app browser journey",
+    "CSOC-UC-010/011 isolated registration and invitation browser journeys",
+    "Independent caller authentication, tenant/template scope, limits and scoped status",
+    "Platform sender and independent ledger backup custody admission",
+    "Named inbound/reply/bounce operations, alignment and retention",
+    "Per-flow productive user acceptance"
+  ]
+}
diff --git a/docs/usecases/first-transfer-review.md b/docs/usecases/first-transfer-review.md
index 234ddff..5777bf6 100644
--- a/docs/usecases/first-transfer-review.md
+++ b/docs/usecases/first-transfer-review.md
@@ -32,7 +32,10 @@ accept migration or a live release.
   Private page covers are visible per founder review. Missing Spaces-list
   preview is corrected in revision15; live owner preview/hash preservation and
   actual production-pair isolated recovery pass. List-preview review is pending.
-- Writer, reader and outsider access; sharing and portability UX: pending T04.
+- Writer, reader and outsider access; owner sharing/revocation, personal export
+  and retained-content exit UI are implemented locally and browser-tested.
+  Release and productive user review remain T04; see
+  [implementation review](../release/sharing-portability-review-2026-10-08.md).
 - Content restart durability and paired real-content isolated restore verified.
   Durable backup custody/retention and operational rollback remain T02.
 
diff --git a/docs/usecases/platform-communication.md b/docs/usecases/platform-communication.md
index 43e3155..44a830b 100644
--- a/docs/usecases/platform-communication.md
+++ b/docs/usecases/platform-communication.md
@@ -5,10 +5,11 @@ SMTP; application invitation/verification delivery uses the existing
 email-connect service. ReichelAg protocol distribution remains UC-008's manual
 clipboard/email workflow.
 
-These stable IDs extend the discovery catalogue. They are not yet entries in
-the executable product registry: owner-spanning browser coverage is still
-required under T06. Personal recovery has user acceptance; the gap in its
-automated end-to-end protection remains explicit.
+These stable IDs are registered in `registry.json` with synthetic fixture
+references, app-side fast checks and `established: false`. Owner-spanning browser
+coverage is still required under T06. Personal recovery retains its recorded
+user acceptance; it is not marked as an established automated journey until
+its full fast/browser contract can be protected. UC-010–012 remain candidates.
 
 | ID | Actor, goal and steps | Expected outcome / evidence | Status and owner |
 | --- | --- | --- | --- |
@@ -36,11 +37,11 @@ live sends are part of the gate.
 | Registration handoff | `tests/test_shell.py::test_registration_link_uses_only_configured_destination` | UC-010 browser request/verify/cancel; preserve tenant/client binding through owner flow |
 | Invitation auth/template/recipient/key/suppression | email-connect `tests/test_transactional.py`: `test_rejects_auth_recipient_template_and_key`, `test_suppression_blocks_send` | Separate caller identities, caller/template/tenant scope, request limits; no authority from payload `source` |
 | Invitation retry / uncertain outcome | Owner tests `test_sends_fixed_template_once`, `test_resend_is_separate_event_and_sends_again`, `test_lost_post_send_record_never_resends_after_restart`, `test_definitive_failure_retries_but_changed_payload_is_rejected`, `test_disconnect_after_smtp_acceptance_never_releases_reservation` | Per-caller event namespace, bounded retry schedule and operator handling of unknown outcomes |
-| Verification privacy and replay | Owner tests `test_registration_verification_is_digest_only_and_single_use`, `test_registration_cancellation_is_single_use_and_prevents_verification`, `test_mailbox_evidence_is_not_authorization` | Retry-safe challenge creation/submission; expired-handle and binding denials through browser; failure/redaction across every verification path |
+| Verification privacy and replay | Owner tests `test_registration_verification_is_digest_only_and_single_use`, `test_registration_cancellation_is_single_use_and_prevents_verification`, `test_mailbox_evidence_is_not_authorization`, plus retry/restart/concurrency functions bound below | Expired-handle and binding denials through an isolated owner-spanning browser journey |
 | Provider failure / diagnostic redaction | Owner tests `test_provider_timeout_temporary_and_permanent_are_redacted`, `test_status_authenticates_without_sending_and_redacts_errors` | No tokens, recipient/body or provider details in diagnostic projections; caller-scoped status; provider acceptance and inbox receipt shown separately |
 | Reply/bounce operations | Offline scanner fixtures exist in email-connect | Named monitored inbox, authorized inbound access, correlated bounce → suppression, bounded retention and support escalation |
 
-Fresh owner baseline: 27 transactional tests pass at source
+Historical owner baseline (2026-10-07): 27 transactional tests pass at source
 `73702b7e1a1671948b0545ef32d6e0de9cca9c65`, clean checkout.
 This is local source evidence, not a deployed version or fresh inbox receipt.
 Reproduction from this repository's installed Python environment:
@@ -52,7 +53,28 @@ PYTHONDONTWRITEBYTECODE=1 PYTHONPATH=/home/worsch/email-connect/src \
   --basetemp=/tmp/csoc-email-owner-tests
 ```
 
-Before registering these as protected executable journeys, bind exact fast and
-browser node IDs in their owning repositories, arrange the isolated cross-owner
-harness, and link owner regression receipts here. `make check` currently
-protects UC-008; it does not execute the issuer/email-connect suites.
+## Reproducible owner regression gate — 2026-10-08
+
+Run `make check-communication EMAIL_CONNECT_ROOT=/path/to/email-connect`.
+`communication-regressions.json` binds 21 required test functions covering
+authorization/template/recipient denial, suppression, provider failure and
+redaction, invitation uncertainty and verification restart/concurrency safety.
+The runner copies only Python source and that synthetic test module to a private
+temporary tree. It denies socket connects and DNS, strips inherited credentials,
+disables plugin autoload, and refuses removed or skipped/xfail contract coverage.
+It leaves the owner checkout untouched. Gate tests in `make check` prove those
+failure boundaries. No mailbox, SMTP, issuer or live account is contacted.
+
+The redacted receipt at `var/test-results/communication.json` binds exact
+executed source/test/contract hashes and records counts, missing tests and
+outstanding acceptance. The current owner check passes **39 tests, zero skips**.
+This closes the stale verification-retry baseline above: accepted and uncertain
+outcomes now retain their reservations across retries/restarts; definitive
+retryable refusals cancel the failed challenge before retry.
+
+Before marking UC-009–012 as established protected journeys, bind the missing
+browser node IDs in their owners, arrange the isolated issuer/mailbox/application
+harness, and record owner admission. `make check` protects UC-008 and tests the
+new app UI; `check-communication` is a separate explicitly selected owner gate.
+Neither check closes independent caller/sender/limits, ledger backup admission,
+inbox ownership, DNS alignment or productive per-flow user acceptance.
diff --git a/docs/usecases/registry.json b/docs/usecases/registry.json
index 98b7b87..ed06615 100644
--- a/docs/usecases/registry.json
+++ b/docs/usecases/registry.json
@@ -35,6 +35,93 @@
         "Paste into the user's usual mail client and review presentation",
         "Confirm live persistence and measured paired restore before transfer"
       ]
+    },
+    {
+      "id": "CSOC-UC-009",
+      "title": "Personal account recovery",
+      "established": false,
+      "confirmation": "user-confirmed",
+      "transfer_status": "accepted",
+      "narrative": "docs/usecases/platform-communication.md",
+      "fixture": "tests/usecases/fixtures/platform-communication-009.json",
+      "contract": [
+        "Request a new password reset, receive it privately and sign in to the workspace",
+        "Identity credentials and reset handles remain outside the application"
+      ],
+      "tests": {
+        "fast": [
+          "tests/test_identity_regressions.py::test_consumed_callback_state_cannot_be_replayed",
+          "tests/test_identity_regressions.py::test_same_email_different_identity_cannot_take_over_member"
+        ],
+        "browser": []
+      },
+      "owner_regression_contract": "docs/usecases/communication-regressions.json",
+      "manual_review": [
+        "Isolated owner-spanning browser coverage and admission remain required"
+      ],
+      "acceptance_ref": "history/20261006T185411Z-personal-workspace-acceptance.md"
+    },
+    {
+      "id": "CSOC-UC-010",
+      "title": "Registration verification",
+      "established": false,
+      "confirmation": "inferred",
+      "transfer_status": "pending-user-review",
+      "narrative": "docs/usecases/platform-communication.md",
+      "fixture": "tests/usecases/fixtures/platform-communication-010.json",
+      "contract": [
+        "Single-use tenant/client-bound verification is retry-safe and conveys no authorization"
+      ],
+      "tests": {
+        "fast": [
+          "tests/test_shell.py::test_registration_link_uses_only_configured_destination"
+        ],
+        "browser": []
+      },
+      "owner_regression_contract": "docs/usecases/communication-regressions.json",
+      "manual_review": [
+        "Isolated owner-spanning browser coverage and admission remain required"
+      ]
+    },
+    {
+      "id": "CSOC-UC-011",
+      "title": "Member invitation",
+      "established": false,
+      "confirmation": "inferred",
+      "transfer_status": "pending-user-review",
+      "narrative": "docs/usecases/platform-communication.md",
+      "fixture": "tests/usecases/fixtures/platform-communication-011.json",
+      "contract": [
+        "Fixed invitation template, one provider submission per event, suppression and safe retries"
+      ],
+      "tests": {
+        "fast": [],
+        "browser": []
+      },
+      "owner_regression_contract": "docs/usecases/communication-regressions.json",
+      "manual_review": [
+        "Isolated owner-spanning browser coverage and admission remain required"
+      ]
+    },
+    {
+      "id": "CSOC-UC-012",
+      "title": "Application notification and reply",
+      "established": false,
+      "confirmation": "inferred",
+      "transfer_status": "deferred",
+      "narrative": "docs/usecases/platform-communication.md",
+      "fixture": "tests/usecases/fixtures/platform-communication-012.json",
+      "contract": [
+        "Each application notification needs an admitted caller, template, recipient purpose and monitored reply route"
+      ],
+      "tests": {
+        "fast": [],
+        "browser": []
+      },
+      "owner_regression_contract": "docs/usecases/communication-regressions.json",
+      "manual_review": [
+        "Isolated owner-spanning browser coverage and admission remain required"
+      ]
     }
   ]
 }
diff --git a/scripts/check-communication.py b/scripts/check-communication.py
new file mode 100644
index 0000000..bb96687
--- /dev/null
+++ b/scripts/check-communication.py
@@ -0,0 +1,114 @@
+#!/usr/bin/env python3
+"""Run exact owner retry/privacy regressions on a private, network-denied snapshot.
+
+Only source and one synthetic test module are copied. The owner's configuration,
+environment, caches and runtime databases are neither read nor mutated.
+"""
+
+import argparse
+import hashlib
+import json
+import os
+import subprocess
+import sys
+import tempfile
+import xml.etree.ElementTree as ET
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+CONTRACT = ROOT / "docs/usecases/communication-regressions.json"
+GUARD = '''
+import socket
+import pytest
+
+def forbidden(*args, **kwargs):
+    raise RuntimeError("Communication regressions forbid all network access")
+
+def pytest_sessionstart(session):
+    socket.socket.connect = forbidden
+    socket.socket.connect_ex = forbidden
+    socket.getaddrinfo = forbidden
+    socket.create_connection = forbidden
+
+def pytest_collection_modifyitems(items):
+    for item in items:
+        if any(item.get_closest_marker(m) for m in ("skip", "skipif", "xfail")):
+            raise pytest.UsageError("Communication contracts cannot skip or xfail")
+'''
+
+
+def check(owner, receipt):
+    contract = json.loads(CONTRACT.read_text(encoding="utf-8"))
+    if contract["schema_version"] != 1:
+        raise ValueError("Unsupported communication contract")
+    owner = owner.resolve(strict=True)
+    source = owner / "src/email_connect"
+    test = owner / contract["test_file"]
+    if not source.is_dir() or not test.is_file() or source.is_symlink() or test.is_symlink():
+        raise ValueError("Owner source and synthetic test module must be regular local files")
+    files = sorted(source.rglob("*.py")) + [test]
+    if any(p.is_symlink() for p in files):
+        raise ValueError("Owner Python sources must not be symlinks")
+    # Snapshot exact bytes first. Hash receipts bind the code actually executed,
+    # including an uncommitted source change, rather than assuming a HEAD pin.
+    hashes = {}
+    with tempfile.TemporaryDirectory(prefix="csoc-communication-") as private:
+        workspace = Path(private)
+        for path in files:
+            relative = path.relative_to(owner)
+            data = path.read_bytes()
+            hashes[str(relative)] = hashlib.sha256(data).hexdigest()
+            target = workspace / relative
+            target.parent.mkdir(parents=True, exist_ok=True)
+            target.write_bytes(data)
+        (workspace / "conftest.py").write_text(GUARD, encoding="utf-8")
+        (workspace / "pytest.ini").write_text("[pytest]\n", encoding="utf-8")
+        report = workspace / "result.xml"
+        result = subprocess.run(
+            [sys.executable, "-m", "pytest", "-q", "-c", str(workspace / "pytest.ini"),
+             str(workspace / contract["test_file"]), "-p", "no:cacheprovider",
+             "--junitxml", str(report), "--basetemp", str(workspace / "test-data")],
+            cwd=workspace, capture_output=True, timeout=120,
+            env={"PATH": os.defpath, "PYTHONPATH": str(workspace / "src"),
+                 "PYTHONDONTWRITEBYTECODE": "1", "PYTEST_DISABLE_PLUGIN_AUTOLOAD": "1"},
+        )
+        cases = ET.parse(report).findall(".//testcase") if report.is_file() else []
+        covered = {case.attrib["name"].split("[", 1)[0] for case in cases}
+        missing = sorted(set(contract["required_tests"]) - covered)
+        disabled = sum(len(case.findall("skipped")) for case in cases)
+        failed = sum(len(case.findall("failure")) + len(case.findall("error")) for case in cases)
+        passed = result.returncode == 0 and bool(cases) and not (missing or disabled or failed)
+        evidence = {
+            "schema_version": 1, "owner": contract["owner"], "passed": passed,
+            "network": "all socket connects and DNS resolution denied",
+            "tests": len(cases), "skipped": disabled, "failed": failed,
+            "missing_required_tests": missing, "source_sha256": hashes,
+            "contract_sha256": hashlib.sha256(CONTRACT.read_bytes()).hexdigest(),
+            "acceptance_complete": False,
+            "remaining_acceptance": contract["remaining_acceptance"],
+        }
+        # Do not publish raw pytest output: reports contain no message bodies,
+        # handles, bearer values or provider diagnostics, including on failures.
+        receipt.parent.mkdir(parents=True, exist_ok=True)
+        receipt.write_text(json.dumps(evidence, indent=2) + "\n", encoding="utf-8")
+        return evidence
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--owner", type=Path, required=True)
+    parser.add_argument("--receipt", type=Path,
+                        default=ROOT / "var/test-results/communication.json")
+    args = parser.parse_args()
+    try:
+        evidence = check(args.owner, args.receipt)
+    except (OSError, ValueError, KeyError, subprocess.TimeoutExpired, ET.ParseError):
+        print("Communication check could not produce a valid isolated receipt", file=sys.stderr)
+        return 1
+    print(json.dumps({key: evidence[key] for key in
+                      ("passed", "tests", "skipped", "failed", "missing_required_tests")}))
+    return 0 if evidence["passed"] else 1
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/scripts/test-sharing-browser.mjs b/scripts/test-sharing-browser.mjs
new file mode 100644
index 0000000..c59b290
--- /dev/null
+++ b/scripts/test-sharing-browser.mjs
@@ -0,0 +1,71 @@
+import assert from 'node:assert/strict';
+import { chromium } from 'playwright';
+
+const base = new URL(process.argv[2]);
+if (base.protocol !== 'http:' || !['localhost', '127.0.0.1'].includes(base.hostname)) {
+  throw new Error('Sharing checks require an isolated loopback server');
+}
+const browser = await chromium.launch({headless: true});
+try {
+  const context = await browser.newContext();
+  await context.route('**/*', route => new URL(route.request().url()).origin === base.origin
+    ? route.continue() : route.abort());
+  const page = await context.newPage();
+  page.setDefaultTimeout(10000);
+  async function login(subject) {
+    await page.goto(`${base.origin}/auth/dev-login/`);
+    await page.getByLabel('Subject').fill(subject);
+    await page.getByLabel('Tenant').fill('tenant:sharing-test');
+    await page.getByRole('button', {name: 'Establish session'}).click();
+    await page.waitForURL('**/app/');
+  }
+  const detail = `${base.origin}/app/spaces/shared-browser/`;
+  await login('sharing-reader');
+  await page.goto(`${base.origin}/account/data/`);
+  const readerId = await page.locator('main code').first().innerText();
+  assert.match(readerId, /^[0-9a-f-]{36}$/);
+  await login('sharing-owner');
+  await page.goto(detail);
+  await page.getByRole('link', {name: 'Share space', exact: true}).click();
+  await page.getByLabel('Member ID').fill(readerId);
+  await page.getByLabel('Access', {exact: true}).selectOption('viewer');
+  await page.getByRole('button', {name: 'Update access'}).click();
+  await page.waitForURL('**/sharing/');
+  assert.match(await page.locator('main').innerText(), /Space access updated/);
+  await login('sharing-reader');
+  await page.goto(`${detail}?page=notes`);
+  assert.match(await page.locator('#page-content').innerText(), /Original notes/);
+  assert.equal(await page.getByRole('link', {name: 'Share space', exact: true}).count(), 0);
+  assert.equal(await page.getByRole('link', {name: 'Edit page', exact: true}).count(), 0);
+  await login('sharing-owner');
+  await page.goto(`${detail}pages/notes/edit/`);
+  const otherTab = await context.newPage();
+  await otherTab.goto(`${detail}pages/notes/edit/`);
+  await page.getByLabel('Body (markdown)').fill('First saved notes');
+  await page.getByRole('button', {name: 'Save page'}).click();
+  await page.waitForURL('**?page=notes');
+  await otherTab.getByLabel('Body (markdown)').fill('Unsaved second-tab notes');
+  await otherTab.getByRole('button', {name: 'Save page'}).click();
+  assert.match(await otherTab.locator('main').innerText(), /Reopen it and merge/);
+  assert.equal(await otherTab.getByLabel('Body (markdown)').inputValue(), 'Unsaved second-tab notes');
+  await otherTab.close();
+  await page.goto(`${detail}sharing/`);
+  await page.getByLabel('Member ID').fill(readerId);
+  await page.getByLabel('Access', {exact: true}).selectOption('owner');
+  await page.getByRole('button', {name: 'Update access'}).click();
+  await page.waitForURL('**/sharing/');
+  await page.goto(`${base.origin}/account/data/`);
+  await page.getByLabel('Type DELETE to remove your local account').fill('DELETE');
+  await page.getByRole('button', {name: 'Remove local account'}).click();
+  await page.waitForURL(base.origin + '/');
+  assert.equal(await page.locator('header').getByRole('link', {name: 'Sign in', exact: true}).count(), 1);
+  await login('sharing-reader');
+  await page.goto(`${detail}?page=notes`);
+  assert.match(await page.locator('#page-content').innerText(), /First saved notes/);
+  await page.goto(`${base.origin}/account/data/`);
+  assert.match(await page.locator('main').innerText(), /Before removal/);
+  assert.equal(await page.getByRole('button', {name: 'Remove local account'}).count(), 0);
+  console.log('Sharing, concurrent edits and retained-content exit passed');
+} finally {
+  await browser.close();
+}
diff --git a/tests/test_communication_gate.py b/tests/test_communication_gate.py
new file mode 100644
index 0000000..ad47813
--- /dev/null
+++ b/tests/test_communication_gate.py
@@ -0,0 +1,57 @@
+"""Prove the cross-owner gate cannot send, hide skips or leak inherited credentials."""
+
+import importlib.util
+import json
+from pathlib import Path
+
+import pytest
+
+
+@pytest.fixture
+def gate(tmp_path, monkeypatch):
+    script = Path(__file__).resolve().parents[1] / "scripts/check-communication.py"
+    spec = importlib.util.spec_from_file_location("communication_gate", script)
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    contract = tmp_path / "contract.json"
+    contract.write_text(json.dumps({
+        "schema_version": 1, "owner": "synthetic-owner",
+        "test_file": "tests/test_contract.py", "required_tests": ["test_contract"],
+        "remaining_acceptance": ["User review remains separate"],
+    }))
+    monkeypatch.setattr(module, "CONTRACT", contract)
+    owner = tmp_path / "owner"
+    (owner / "src/email_connect").mkdir(parents=True)
+    (owner / "src/email_connect/__init__.py").write_text("")
+    (owner / "tests").mkdir()
+    return module, owner, tmp_path / "receipt.json"
+
+
+def test_communication_gate_scrubs_credentials_and_does_not_modify_owner(gate, monkeypatch):
+    module, owner, receipt = gate
+    monkeypatch.setenv("SMTP_PASSWORD", "synthetic-inherited-secret")
+    test = owner / "tests/test_contract.py"
+    test.write_text(
+        "import os\ndef test_contract():\n    assert 'SMTP_PASSWORD' not in os.environ\n"
+    )
+    before = sorted(p.relative_to(owner) for p in owner.rglob("*"))
+    evidence = module.check(owner, receipt)
+    assert evidence["passed"] and evidence["tests"] == 1
+    assert evidence["acceptance_complete"] is False
+    assert "synthetic-inherited-secret" not in receipt.read_text()
+    assert sorted(p.relative_to(owner) for p in owner.rglob("*")) == before
+
+
+@pytest.mark.parametrize("body", [
+    ("import socket\ndef test_contract():\n"
+     "    socket.create_connection(('smtp.example.test', 25))\n"),
+    "import pytest\n@pytest.mark.skip\ndef test_contract():\n    pass\n",
+    "def test_renamed():\n    pass\n",
+])
+def test_communication_gate_refuses_network_disabled_or_missing_contract(gate, body):
+    module, owner, receipt = gate
+    (owner / "tests/test_contract.py").write_text(body)
+    evidence = module.check(owner, receipt)
+    assert evidence["passed"] is False
+    assert "smtp.example.test" not in receipt.read_text()
+    assert "RuntimeError" not in receipt.read_text()
diff --git a/tests/test_content_revisions.py b/tests/test_content_revisions.py
new file mode 100644
index 0000000..828ee4c
--- /dev/null
+++ b/tests/test_content_revisions.py
@@ -0,0 +1,285 @@
+"""Conflict/failure and attachment fidelity checks with synthetic local content."""
+
+import subprocess
+import sys
+from concurrent.futures import ThreadPoolExecutor
+from pathlib import Path
+
+import pytest
+from django.urls import reverse
+
+from coulomb_social.apps.spaces import pageops
+from coulomb_social.apps.spaces.services import create_space, save_space_page
+from tests.test_space_permissions import make_member
+
+
+@pytest.fixture
+def trees(tmp_path, settings):
+    settings.CONTENT_ROOT = str(tmp_path / "content")
+    for slug in ("source", "destination"):
+        pageops.init_space_content(slug, title=slug)
+    return tmp_path / "content"
+
+
+def test_simultaneous_edits_have_one_winner_and_durable_old_and_new_versions(trees):
+    before = pageops.write_page("source", "notes", title="Notes", body="Original")
+    original = Path(before.path).read_bytes()
+
+    def save(body):
+        try:
+            pageops.write_page("source", "notes", title="Notes", body=body,
+                               expected_revision=before.revision)
+            return "saved"
+        except pageops.PageOpsError:
+            return "conflict"
+
+    with ThreadPoolExecutor(max_workers=2) as pool:
+        assert sorted(pool.map(save, ("First edit", "Second edit"))) == ["conflict", "saved"]
+    versions = [p.read_bytes() for p in (trees / ".revisions/source/notes").glob("*.md")]
+    assert original in versions
+    assert Path(before.path).read_bytes() in versions
+    assert len(versions) == 2
+    pageops.delete_page("source", "notes")
+    assert not Path(before.path).exists()
+    assert original in versions
+
+
+def test_failed_atomic_publish_leaves_original_readable_and_history_retained(trees, monkeypatch):
+    doc = pageops.write_page("source", "notes", title="Notes", body="Original")
+    original = Path(doc.path).read_bytes()
+    replace = pageops.os.replace
+
+    def fail_page(source, destination):
+        if Path(destination) == Path(doc.path):
+            raise OSError("synthetic disk failure")
+        return replace(source, destination)
+
+    monkeypatch.setattr(pageops.os, "replace", fail_page)
+    with pytest.raises(OSError):
+        pageops.write_page("source", "notes", title="Notes", body="New")
+    assert Path(doc.path).read_bytes() == original
+    assert sorted(p.name for p in Path(doc.path).parent.iterdir()) == ["index.md", "notes.md"]
+
+
+def test_empty_imported_page_has_a_real_revision_and_can_be_edited(trees):
+    pageops.page_file("source", "empty").write_bytes(b"")
+    source = pageops.read_page("source", "empty")
+    assert source.exists and source.revision
+    pageops.write_page("source", "empty", body="New notes", expected_revision=source.revision)
+    assert pageops.read_page("source", "empty").body == "New notes\n"
+    assert any(p.read_bytes() == b"" for p in (trees / ".revisions/source/empty").glob("*.md"))
+
+
+@pytest.mark.parametrize("operation", ["copy", "move"])
+def test_body_assets_reference_links_visual_and_nested_equal_names_survive(trees, operation):
+    assets = pageops.assets_dir("source")
+    (assets / "nested").mkdir()
+    (assets / "diagram.png").write_bytes(b"synthetic image one")
+    (assets / "nested/diagram.png").write_bytes(b"synthetic image two")
+    body = ('![Diagram](../assets/diagram.png)\n'
+            '![Nested][picture]\n\n[picture]: assets/nested/diagram.png\n'
+            '[File](assets/diagram.png#detail)\n')
+    source = pageops.write_page("source", "notes", title="Notes", body=body,
+                                visual="assets/diagram.png")
+    original = Path(source.path).read_bytes()
+    if operation == "copy":
+        doc = pageops.copy_page("source", "notes", "destination", "new-notes")
+        assert Path(source.path).read_bytes() == original
+    else:
+        doc = pageops.transfer_page("source", "notes", "destination", "new-notes")
+        assert not Path(source.path).exists()
+    assert doc.visual == "assets/new-notes-diagram.png"
+    assert "![Diagram](assets/new-notes-diagram.png)" in doc.body
+    assert "[File](assets/new-notes-diagram.png#detail)" in doc.body
+    assert "assets/nested/" not in doc.body
+    assert sorted(p.read_bytes() for p in pageops.assets_dir("destination").iterdir()) == [
+        b"synthetic image one", b"synthetic image two",
+    ]
+
+
+def test_attachment_failure_rolls_back_partial_copy_and_does_not_move_source(trees):
+    (pageops.assets_dir("source") / "present.png").write_bytes(b"synthetic image")
+    source = pageops.write_page("source", "notes", title="Notes",
+                                body="![One](assets/present.png)\n![Two](assets/missing.png)")
+    before = Path(source.path).read_bytes()
+    with pytest.raises(pageops.PageOpsError, match="attachment safely"):
+        pageops.transfer_page("source", "notes", "destination", "notes")
+    assert Path(source.path).read_bytes() == before
+    assert list(pageops.assets_dir("destination").iterdir()) == []
+    assert not pageops.read_page("destination", "notes").exists
+
+
+@pytest.mark.django_db
+def test_stale_rename_and_missing_revision_preserve_user_input_and_current_page(trees, client):
+    owner = make_member("owner")
+    space = create_space(owner, title="Conflict", slug="conflict")
+    before = pageops.write_page(space.slug, "notes", title="Notes", body="Original")
+    pageops.write_page(space.slug, "notes", title="Notes", body="Other writer")
+    client.force_login(owner.user)
+    url = reverse("spaces:page_edit", args=[space.slug, "notes"])
+    for revision in (None, before.revision):
+        fields = {"title": "Mine", "slug": "renamed", "body": "My unsaved notes"}
+        if revision is not None:
+            fields["revision"] = revision
+        response = client.post(url, fields)
+        assert response.status_code == 200
+        assert b"Reopen it and merge" in response.content
+        assert b"My unsaved notes" in response.content
+        assert pageops.read_page(space.slug, "notes").body == "Other writer\n"
+        assert not pageops.read_page(space.slug, "renamed").exists
+    current = pageops.read_page(space.slug, "notes")
+    save_space_page(owner, space, "notes", "renamed", expected_revision=current.revision,
+                    title="Merged", body="Other writer plus my notes")
+    assert not pageops.read_page(space.slug, "notes").exists
+
+
+@pytest.mark.django_db
+def test_space_edit_conflict_does_not_overwrite_new_index_body_or_metadata(trees, client):
+    owner = make_member("owner")
+    space = create_space(owner, title="Conflict", slug="conflict")
+    before = pageops.read_page(space.slug, "index")
+    pageops.write_page(space.slug, "index", title="Conflict", body="Another writer's index",
+                       extra_meta={"source_id": "synthetic-source"})
+    client.force_login(owner.user)
+    fields = {"title": "My title", "abstractor": "My abstract", "revision": before.revision}
+    url = reverse("spaces:edit", args=[space.slug])
+    response = client.post(url, fields)
+    assert b"space changed" in response.content and b"My title" in response.content
+    space.refresh_from_db()
+    assert space.title == "Conflict"
+    current = pageops.read_page(space.slug, "index")
+    assert current.body == "Another writer's index\n"
+    fields["revision"] = current.revision
+    assert client.post(url, fields).status_code == 302
+    assert pageops.read_page(space.slug, "index").meta["source_id"] == "synthetic-source"
+
+
+def test_page_symlink_cannot_read_or_overwrite_another_space(trees):
+    target = pageops.page_file("destination", "index")
+    pageops.page_file("source", "linked").symlink_to(target)
+    before = target.read_bytes()
+    with pytest.raises(pageops.PageOpsError, match="symlink"):
+        pageops.read_page("source", "linked")
+    with pytest.raises(pageops.PageOpsError, match="symlink"):
+        pageops.write_page("source", "linked", body="Tampered")
+    assert target.read_bytes() == before
+
+
+@pytest.mark.django_db
+def test_incoming_page_addresses_survive_rename_move_and_enforce_every_grant(trees, client):
+    from coulomb_social.apps.spaces.services import set_space_access, transfer_space_page
+
+    owner, reader = make_member("owner"), make_member("reader")
+    source = create_space(owner, title="Shared", slug="shared")
+    target = create_space(owner, title="Private", slug="private")
+    set_space_access(owner, source, reader.pk, "viewer")
+    doc = pageops.write_page(source.slug, "notes", title="Notes", body="Retained content")
+    save_space_page(owner, source, "notes", "renamed", expected_revision=doc.revision,
+                    title="Notes", body=doc.body)
+    client.force_login(reader.user)
+    old_url = reverse("spaces:detail", args=[source.slug]) + "?page=notes"
+    response = client.get(old_url, follow=True)
+    assert response.status_code == 200
+    assert b"Retained content" in response.content
+    transfer_space_page(owner, source, "renamed", target, dest_slug="moved")
+    assert client.get(old_url).status_code == 404
+    assert b"Private" not in client.get(old_url).content
+    set_space_access(owner, target, reader.pk, "viewer")
+    response = client.get(old_url, follow=True)
+    assert response.status_code == 200
+    assert b"Retained content" in response.content
+    assert response.redirect_chain == [
+        (reverse("spaces:detail", args=[target.slug]) + "?page=moved", 302),
+    ]
+    with pytest.raises(pageops.PageOpsError, match="reserved"):
+        pageops.write_page(source.slug, "notes", body="Hijack previous address")
+    set_space_access(owner, source, reader.pk, "remove")
+    assert client.get(old_url).status_code == 404
+
+
+def test_failed_destination_publish_rolls_back_assets_and_keeps_source(trees, monkeypatch):
+    assets = pageops.assets_dir("source")
+    (assets / "diagram.png").write_bytes(b"synthetic image")
+    source = pageops.write_page("source", "notes", body="![Diagram](assets/diagram.png)")
+    before = Path(source.path).read_bytes()
+    original = pageops.os.replace
+
+    def fail_target(old, new):
+        if Path(new) == pageops.page_file("destination", "notes"):
+            raise OSError("synthetic destination failure")
+        return original(old, new)
+
+    monkeypatch.setattr(pageops.os, "replace", fail_target)
+    with pytest.raises(OSError):
+        pageops.transfer_page("source", "notes", "destination", "notes")
+    assert Path(source.path).read_bytes() == before
+    assert not pageops.read_page("destination", "notes").exists
+    assert list(pageops.assets_dir("destination").iterdir()) == []
+    assert not pageops.page_aliases("source")
+
+
+@pytest.mark.django_db
+def test_destination_disk_failure_is_visible_without_losing_source(trees, client, monkeypatch):
+    owner = make_member("owner")
+    space = create_space(owner, title="Work", slug="work")
+    source = pageops.write_page(space.slug, "notes", title="Notes", body="Original notes")
+    original = pageops.os.replace
+
+    def fail_target(old, new):
+        if Path(new) == pageops.page_file(space.slug, "copy"):
+            raise OSError("synthetic private storage path must not be disclosed")
+        return original(old, new)
+
+    monkeypatch.setattr(pageops.os, "replace", fail_target)
+    client.force_login(owner.user)
+    response = client.post(reverse("spaces:page_copy", args=[space.slug, source.slug]), {
+        "dest_slug": "copy", "title": "Copy",
+    })
+    assert response.status_code == 200
+    assert b"could not be confirmed" in response.content
+    assert b"private storage path" not in response.content
+    assert pageops.read_page(space.slug, "notes").body == "Original notes\n"
+    assert not pageops.read_page(space.slug, "copy").exists
+
+
+def test_separate_processes_share_the_writer_lock_and_reject_stale_revision(trees):
+    doc = pageops.write_page("source", "notes", title="Notes", body="Original")
+    code = '''
+import sys
+from django.conf import settings
+settings.configure(CONTENT_ROOT=sys.argv[1])
+from coulomb_social.apps.spaces import pageops
+if sys.argv[3] == "hold":
+    with pageops.content_write_lock():
+        print("locked", flush=True)
+        sys.stdin.readline()
+        pageops.write_page("source", "notes", body="First process", expected_revision=sys.argv[2])
+else:
+    print("attempting", flush=True)
+    try:
+        pageops.write_page("source", "notes", body="Second process", expected_revision=sys.argv[2])
+    except pageops.PageOpsError:
+        print("conflict", flush=True)
+'''
+    children = []
+    try:
+        for mode in ("hold", "write"):
+            child = subprocess.Popen(
+                [sys.executable, "-c", code, str(trees), doc.revision, mode],
+                stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True,
+            )
+            children.append(child)
+            assert child.stdout.readline().strip() == ("locked" if mode == "hold" else "attempting")
+        with pytest.raises(subprocess.TimeoutExpired):
+            children[1].communicate(timeout=0.25)
+        _, errors = children[0].communicate(input="release\n", timeout=10)
+        assert children[0].returncode == 0, errors
+        output, errors = children[1].communicate(timeout=10)
+        assert children[1].returncode == 0, errors
+        assert output.strip() == "conflict"
+        assert pageops.read_page("source", "notes").body == "First process\n"
+    finally:
+        for child in children:
+            if child.poll() is None:
+                child.terminate()
+            child.communicate(timeout=10)
diff --git a/tests/test_member_portability.py b/tests/test_member_portability.py
new file mode 100644
index 0000000..0b04bb8
--- /dev/null
+++ b/tests/test_member_portability.py
@@ -0,0 +1,170 @@
+"""App-local sharing/exit with synthetic identities and retained shared work."""
+
+import pytest
+from django.core.exceptions import ValidationError
+from django.test import Client
+from django.urls import reverse
+
+from coulomb_social.apps.members.models import Member, User
+from coulomb_social.apps.members.portability import delete_local_member
+from coulomb_social.apps.spaces import pageops
+from coulomb_social.apps.spaces.models import Space, SpaceMembership
+from coulomb_social.apps.spaces.services import create_space, set_space_access
+from tests.test_space_permissions import make_member
+
+pytestmark = pytest.mark.django_db
+
+
+@pytest.fixture
+def people(tmp_path, settings, client):
+    settings.CONTENT_ROOT = str(tmp_path / "content")
+    owner, reader, outsider = [make_member(s) for s in ("owner", "reader", "outsider")]
+    space = create_space(owner, title="Retained work", slug="retained-work")
+    client.force_login(owner.user)
+    return owner, reader, outsider, space
+
+
+def test_owner_shares_reader_then_revokes_without_email(people, client):
+    owner, reader, _, space = people
+    url = reverse("spaces:sharing", kwargs={"slug": space.slug})
+    assert b"Share space" in client.get(reverse("spaces:detail", args=[space.slug])).content
+    assert client.post(url, {"member_id": str(reader.pk), "role": "viewer"}).status_code == 302
+    client.force_login(reader.user)
+    assert client.get(reverse("spaces:detail", args=[space.slug])).status_code == 200
+    assert client.get(url).status_code == 403
+    assert client.post(url, {"member_id": str(owner.pk), "role": "remove"}).status_code == 403
+    client.force_login(owner.user)
+    assert client.post(url, {"member_id": str(reader.pk), "role": "remove"}).status_code == 302
+    client.force_login(reader.user)
+    assert client.get(reverse("spaces:detail", args=[space.slug])).status_code == 404
+
+
+@pytest.mark.parametrize("target", ["foreign", "missing", "malformed"])
+def test_sharing_rejects_foreign_missing_and_malformed_ids(people, client, target):
+    _, _, _, space = people
+    ids = {"foreign": str(make_member("foreign", tenant="tenant:b").pk),
+           "missing": "00000000-0000-0000-0000-000000000000", "malformed": "bad-id"}
+    url = reverse("spaces:sharing", args=[space.slug])
+    response = client.post(url, {"member_id": ids[target], "role": "owner"})
+    assert response.status_code == 200
+    assert b"existing member in this tenant" in response.content
+    assert space.memberships.count() == 1
+
+
+def test_creator_and_last_owner_cannot_be_revoked(people):
+    owner, reader, _, space = people
+    with pytest.raises(pageops.PageOpsError, match="creator"):
+        set_space_access(owner, space, owner.pk, "remove")
+    set_space_access(owner, space, reader.pk, "owner")
+    space.created_by = None
+    space.save()
+    set_space_access(reader, space, owner.pk, "remove")
+    with pytest.raises(pageops.PageOpsError, match="at least one owner"):
+        set_space_access(reader, space, reader.pk, "viewer")
+
+
+def test_export_is_personal_tenant_scoped_and_never_exports_secrets(people, client):
+    owner, reader, _, space = people
+    reader.email = "other-person@example.test"
+    reader.save()
+    set_space_access(owner, space, reader.pk, "viewer")
+    foreign = Space.objects.create(tenant_id="tenant:b", slug="foreign", title="Foreign")
+    SpaceMembership.objects.create(space=foreign, member=owner, role="viewer")
+    session = client.session
+    session["access_token"] = "synthetic-secret"
+    session.save()
+    response = client.get(reverse("core:account_export"))
+    assert response.status_code == 200
+    assert response["Cache-Control"] == "private, no-store"
+    assert response["Content-Disposition"].startswith("attachment;")
+    data = response.json()
+    assert data["member"]["id"] == str(owner.pk)
+    assert [g["space_slug"] for g in data["memberships"]] == [space.slug]
+    for private in (b"synthetic-secret", b"other-person@example.test", b"password", b"Foreign"):
+        assert private not in response.content
+    client.force_login(reader.user)
+    assert client.get(reverse("core:account_export")).json()["member"]["id"] == str(reader.pk)
+
+
+@pytest.mark.parametrize("archived", [False, True])
+def test_exit_blocks_last_owner_and_retains_content(people, client, archived):
+    owner, _, _, space = people
+    space.is_active = not archived
+    space.save()
+    before = pageops.page_file(space.slug, "index").read_bytes()
+    url = reverse("core:account_data")
+    assert b"Before removal" in client.get(url).content
+    assert client.post(url, {"confirmation": "DELETE"}).status_code == 200
+    assert Member.objects.filter(pk=owner.pk).exists()
+    assert pageops.page_file(space.slug, "index").read_bytes() == before
+
+
+def test_exit_with_successor_removes_local_grants_and_all_old_sessions(people, client):
+    owner, reader, _, space = people
+    set_space_access(owner, space, reader.pk, "owner")
+    other_session = Client()
+    other_session.force_login(owner.user)
+    before = pageops.page_file(space.slug, "index").read_bytes()
+    url = reverse("core:account_data")
+    assert client.post(url, {"confirmation": "wrong"}).status_code == 200
+    response = client.post(url, {"confirmation": "DELETE"})
+    assert response.status_code == 302
+    assert not Member.objects.filter(pk=owner.pk).exists()
+    assert not User.objects.filter(pk=owner.user_id).exists()
+    space.refresh_from_db()
+    assert space.created_by_id is None
+    assert pageops.page_file(space.slug, "index").read_bytes() == before
+    assert other_session.get(reverse("core:app_home")).status_code == 302
+    client.force_login(reader.user)
+    assert client.get(reverse("spaces:detail", args=[space.slug])).status_code == 200
+
+
+def test_inactive_successor_cannot_release_owner_responsibility(people):
+    owner, reader, _, space = people
+    set_space_access(owner, space, reader.pk, "owner")
+    reader.user.is_active = False
+    reader.user.save()
+    with pytest.raises(pageops.PageOpsError, match="another active member"):
+        delete_local_member(owner)
+
+
+def test_account_and_sharing_posts_require_csrf(people):
+    owner, reader, _, space = people
+    guarded = Client(enforce_csrf_checks=True)
+    guarded.force_login(owner.user)
+    assert guarded.post(reverse("core:account_data"), {"confirmation": "DELETE"}).status_code == 403
+    assert guarded.post(reverse("spaces:sharing", args=[space.slug]), {
+        "member_id": str(reader.pk), "role": "owner",
+    }).status_code == 403
+
+
+def test_admin_validation_rejects_cross_tenant_grants_and_colliding_storage(people):
+    _, _, _, space = people
+    foreign = make_member("foreign", tenant="tenant:b")
+    with pytest.raises(ValidationError, match="another tenant"):
+        SpaceMembership(space=space, member=foreign).full_clean()
+    with pytest.raises(ValidationError, match="already uses that slug"):
+        Space(tenant_id=foreign.tenant_id, slug=space.slug, title="Collision").full_clean()
+
+
+def test_corrupt_foreign_creator_is_blocked_without_disclosing_other_tenant(people, client):
+    owner, _, _, _ = people
+    Space.objects.create(tenant_id="tenant:b", slug="foreign", title="Foreign private title",
+                         created_by=owner)
+    response = client.get(reverse("core:account_data"))
+    assert b"operator review" in response.content
+    assert b"Foreign private title" not in response.content
+    response = client.post(reverse("core:account_data"), {"confirmation": "DELETE"})
+    assert b"Foreign private title" not in response.content
+    assert Member.objects.filter(pk=owner.pk).exists()
+
+
+def test_legacy_ambiguous_storage_denies_pages_lists_and_writes(people, client):
+    owner, _, _, space = people
+    Space.objects.create(tenant_id="tenant:b", slug=space.slug, title="Collision")
+    assert client.get(reverse("spaces:detail", args=[space.slug])).status_code == 404
+    assert client.get(reverse("spaces:page_edit", args=[space.slug, "index"])).status_code == 404
+    assert space.title.encode() not in client.get(reverse("core:app_home")).content
+    with pytest.raises(pageops.PageOpsError, match="read-only"):
+        from coulomb_social.apps.spaces.services import put_space_page
+        put_space_page(owner, space, "notes", title="Attempt")
diff --git a/tests/test_reichelag_workflow.py b/tests/test_reichelag_workflow.py
index 75cad7a..ac0b40a 100644
--- a/tests/test_reichelag_workflow.py
+++ b/tests/test_reichelag_workflow.py
@@ -37,7 +37,8 @@ def test_full_protocol_duplicate_edit_and_clipboard_control(tmp_path, settings,
     edited = scenario["next_body"]
     response = client.post(reverse("spaces:page_edit", kwargs={
         "slug": space.slug, "page_slug": "next-call",
-    }), {"title": "Next call", "slug": "next-call", "body": edited})
+    }), {"title": "Next call", "slug": "next-call", "body": edited,
+         "revision": pageops.read_page(space.slug, "next-call").revision})
     assert response.status_code == 302
     assert pageops.read_page(space.slug, "previous-call").body == body
     response = client.get(reverse("spaces:detail", kwargs={"slug": space.slug}) + "?page=next-call")
@@ -99,6 +100,7 @@ def test_protocol_naming_rename_and_collision_safety(tmp_path, settings, client)
         "slug": space.slug, "page_slug": duplicate.slug,
     })
     fields = {"title": "Renamed call", "slug": source.slug,
+              "revision": duplicate.revision,
               "abstractor": duplicate.abstractor, "visual": duplicate.visual,
               "body": duplicate.body}
     response = client.post(edit_url, fields)
@@ -119,7 +121,7 @@ def test_protocol_naming_rename_and_collision_safety(tmp_path, settings, client)
     assert renamed.meta["source_modified_at"] == "12345"
     assert Path(source.path).read_bytes() == source_bytes
     # Changing title alone preserves the filename and imported source metadata.
-    fields.update(title="Corrected title", slug="renamed-call")
+    fields.update(title="Corrected title", slug="renamed-call", revision=renamed.revision)
     response = client.post(reverse("spaces:page_edit", kwargs={
         "slug": space.slug, "page_slug": "renamed-call",
     }), fields)
@@ -137,13 +139,15 @@ def test_protocol_naming_rename_and_collision_safety(tmp_path, settings, client)
     assert Path(renamed.path).read_bytes() == protected
     # Renaming to index is refused; changing an index title cannot move its file.
     fields["slug"] = "index"
+    fields["revision"] = renamed.revision
     response = client.post(reverse("spaces:page_edit", kwargs={
         "slug": space.slug, "page_slug": renamed.slug,
     }), fields)
     assert response.status_code == 200 and b"already exists" in response.content
     response = client.post(reverse("spaces:page_edit", kwargs={
         "slug": space.slug, "page_slug": "index",
-    }), {"title": "Index title", "slug": "move-index", "body": "Index notes\n"})
+    }), {"title": "Index title", "slug": "move-index", "body": "Index notes\n",
+         "revision": pageops.read_page(space.slug, "index").revision})
     assert response.status_code == 302
     assert pageops.read_page(space.slug, "index").title == "Index title"
     assert not pageops.read_page(space.slug, "move-index").exists
diff --git a/tests/test_space_crud.py b/tests/test_space_crud.py
index e1a57c9..45c2b32 100644
--- a/tests/test_space_crud.py
+++ b/tests/test_space_crud.py
@@ -71,7 +71,8 @@ def test_edit_space_updates_index_frontmatter(client, settings, content_root):
     )
     r = client.post(
         reverse("spaces:edit", kwargs={"slug": "lab"}),
-        {"title": "Lab 2", "abstractor": "New abstract", "visual": "assets/v.jpg"},
+        {"title": "Lab 2", "abstractor": "New abstract", "visual": "assets/v.jpg",
+         "revision": pageops.read_page("lab", "index").revision},
     )
     assert r.status_code == 302
     space = Space.objects.get(slug="lab")
@@ -146,6 +147,7 @@ def test_page_crud_copy_transfer(client, settings, content_root):
         reverse("spaces:page_edit", kwargs={"slug": "alpha", "page_slug": "notes"}),
         {
             "title": "Notes v2",
+            "revision": pageops.read_page("alpha", "notes").revision,
             "slug": "notes",
             "abstractor": "Updated",
             "visual": "assets/n.jpg",
diff --git a/tests/usecases/fixtures/platform-communication-009.json b/tests/usecases/fixtures/platform-communication-009.json
new file mode 100644
index 0000000..ffb210a
--- /dev/null
+++ b/tests/usecases/fixtures/platform-communication-009.json
@@ -0,0 +1,8 @@
+{
+  "synthetic": true,
+  "usecase_id": "CSOC-UC-009",
+  "tenant": "tenant:communication-test",
+  "recipient": "member@example.test",
+  "transport": "injected provider; no live sends",
+  "identity_authority": "isolated owner fixture"
+}
diff --git a/tests/usecases/fixtures/platform-communication-010.json b/tests/usecases/fixtures/platform-communication-010.json
new file mode 100644
index 0000000..c665b24
--- /dev/null
+++ b/tests/usecases/fixtures/platform-communication-010.json
@@ -0,0 +1,8 @@
+{
+  "synthetic": true,
+  "usecase_id": "CSOC-UC-010",
+  "tenant": "tenant:communication-test",
+  "recipient": "member@example.test",
+  "transport": "injected provider; no live sends",
+  "identity_authority": "isolated owner fixture"
+}
diff --git a/tests/usecases/fixtures/platform-communication-011.json b/tests/usecases/fixtures/platform-communication-011.json
new file mode 100644
index 0000000..af52f60
--- /dev/null
+++ b/tests/usecases/fixtures/platform-communication-011.json
@@ -0,0 +1,8 @@
+{
+  "synthetic": true,
+  "usecase_id": "CSOC-UC-011",
+  "tenant": "tenant:communication-test",
+  "recipient": "member@example.test",
+  "transport": "injected provider; no live sends",
+  "identity_authority": "isolated owner fixture"
+}
diff --git a/tests/usecases/fixtures/platform-communication-012.json b/tests/usecases/fixtures/platform-communication-012.json
new file mode 100644
index 0000000..9a69011
--- /dev/null
+++ b/tests/usecases/fixtures/platform-communication-012.json
@@ -0,0 +1,8 @@
+{
+  "synthetic": true,
+  "usecase_id": "CSOC-UC-012",
+  "tenant": "tenant:communication-test",
+  "recipient": "member@example.test",
+  "transport": "injected provider; no live sends",
+  "identity_authority": "isolated owner fixture"
+}
diff --git a/tests/usecases/test_sharing_browser.py b/tests/usecases/test_sharing_browser.py
new file mode 100644
index 0000000..1cee22d
--- /dev/null
+++ b/tests/usecases/test_sharing_browser.py
@@ -0,0 +1,35 @@
+"""Candidate sharing/portability journey; synthetic app-only browser checks."""
+
+import subprocess
+from pathlib import Path
+
+import pytest
+
+from coulomb_social.apps.spaces.services import create_space, put_space_page
+from tests.test_space_permissions import make_member
+
+
+@pytest.mark.browser
+@pytest.mark.django_db(transaction=True)
+def test_sharing_conflict_and_account_exit_through_ui(tmp_path, settings, request):
+    settings.DEBUG = True
+    settings.OIDC_ENABLED = False
+    settings.USER_ENGINE_BASE_URL = ""
+    settings.FLEX_AUTH_BASE_URL = ""
+    settings.FORGEJO_BASE_URL = ""
+    settings.CONTENT_ROOT = str(tmp_path / "content")
+    owner = make_member("sharing-owner", tenant="tenant:sharing-test")
+    reader = make_member("sharing-reader", tenant="tenant:sharing-test")
+    # Dev login uses this same exact issuer/subject association.
+    for member in (owner, reader):
+        member.issuer = "https://local.dev/issuer"
+        member.save()
+    space = create_space(owner, title="Synthetic shared work", slug="shared-browser")
+    put_space_page(owner, space, "notes", title="Notes", body="Original notes")
+    server = request.getfixturevalue("live_server")
+    root = Path(__file__).resolve().parents[2]
+    result = subprocess.run(
+        ["node", str(root / "scripts/test-sharing-browser.mjs"), str(server)],
+        cwd=root, capture_output=True, text=True, timeout=120,
+    )
+    assert result.returncode == 0, result.stdout + result.stderr
diff --git a/workplans/CSOC-WP-0008-production-transfer-acceptance.md b/workplans/CSOC-WP-0008-production-transfer-acceptance.md
index 74edba0..ad3eda8 100644
--- a/workplans/CSOC-WP-0008-production-transfer-acceptance.md
+++ b/workplans/CSOC-WP-0008-production-transfer-acceptance.md
@@ -8,7 +8,7 @@ status: active
 owner: codex
 topic_slug: coulomb-social
 created: "2026-10-06"
-updated: "2026-10-07"
+updated: "2026-10-08"
 origin: residual
 origin_ref: CSOC-WP-0007
 depends_on:
@@ -639,3 +639,40 @@ upgrade20.58seconds, app1/1. Read-only live list preview/image bytes, outsider
 exclusion, owner grant and all75stored hashes verified. Health/static200,
 clipboard unchanged. Snapshot-helper pin/7tests/server dry-run pass. T09 awaits
 founder list-preview/full workflow review; other T02/T04/T05 requirements stay open.
+
+
+## Sharing, portability and content revision increment — 2026-10-08
+
+T04 local implementation now provides owner-only Share space grants/revocation
+by exact same-tenant member ID, with viewer/member/owner roles, creator/last-owner
+protection and immediate subsequent-read denial. Your app data exports only the
+requesting member's local records; explicit DELETE removes local Member/User and
+grants, invalidates old sessions and retains shared content with another active
+same-tenant owner. Archived spaces still require a successor. Platform identity
+is separate. Corrupt foreign ownership blocks removal without disclosing names.
+Lists/pages/service writes now deny duplicate slug-keyed storage, and serialized
+app/import/admin writes plus admin validation reject ordinary collisions and
+cross-tenant grants. Production tenancy/privacy and privileged maintenance
+reconciliation remain T04; no database-wide global constraint is claimed.
+
+T05 local implementation adds immutable content-addressed previous/new versions,
+atomic fsync-backed publication, stale page/space form rejection with retained
+input, and cooperating thread/process writer locks. Blank imported pages remain
+editable; original source metadata survives renaming/index edits. Visual and
+Markdown body-linked attachments copy with rewritten destinations and failure
+cleanup; old incoming page addresses survive rename/move with source/destination
+permission checks and reserved-address reuse denial. Replacing an imported tree
+with retained addresses now requires reconciliation. Existing archives are never
+overwritten silently. Raw HTML/custom Markdown, actual corpus fidelity,
+revision retention/capacity acceptance and crash/operational recovery remain open.
+
+Full make check: **182 passed**, Ruff clean, mandatory UC-008 and new sharing/
+concurrent-edit/account-exit Chromium journeys pass. New failure, parallel
+thread/process, tenant, ownership, CSRF, blank-page, attachment and incoming-link
+checks pass. Django system check passes; no schema changes detected. Review:
+docs/release/sharing-portability-review-2026-10-08.md. Source implementation
+choice: decision9ffb5125-5551-4101-9025-5b6f72f40940. This is not acceptance of a
+durable retention policy or authority for deployment/cutover. No private corpus,
+member profile, live image, offsite archive or timer changed. T01/T02/T03/T04/T05/
+T06/T08/T09 remain live for their existing admission, deployment, reconciliation
+and productive user acceptance gates; this workplan remains active.
diff --git a/workplans/CSOC-WP-0010-platform-email-facilities.md b/workplans/CSOC-WP-0010-platform-email-facilities.md
index 213c5d1..16c18d4 100644
--- a/workplans/CSOC-WP-0010-platform-email-facilities.md
+++ b/workplans/CSOC-WP-0010-platform-email-facilities.md
@@ -186,3 +186,32 @@ end-to-end journeys: T06 remains open until isolated issuer/mailbox/app browser
 coverage and owner regression bindings are delivered. UC-008 stays protected by
 make check; protocol distribution remains manual. WP-0008-T07 lint debt closed;
 full application gate98passed. No Bubble/apex cutover or new notification send.
+
+
+## Executable communication regression increment — 2026-10-08
+
+T06 registers UC-009–012 with synthetic fixture references and explicit
+established:false/browser gaps. UC-009 retains its existing personal recovery
+acceptance; the remaining flows are candidates. The UC-008 protected registry
+and manual email distribution remain intact. communication-regressions.json
+binds21 exact owner functions; make check-communication snapshots Python source
+and the synthetic transactional test into a private temporary tree, denies all
+socket connects/DNS, strips inherited credentials, disables plugin autoload,
+refuses skipped/xfail or missing contract tests and produces redacted source/
+test/contract-hash receipts. The owner checkout is not changed.
+
+Actual current owner gate: **39 passed, zero skips**, including verification
+restart/uncertain/concurrent retry safety. Local runner failure tests prove
+network denial, environment isolation and missing/disabled-coverage refusal.
+Application gate: **182 passed**, Ruff and both real Chromium journeys pass.
+Review: docs/release/sharing-portability-review-2026-10-08.md; public owner receipt:
+docs/release/communication-regressions-2026-10-08.json. This closes stale baseline
+reporting, not owner admission or full end-to-end automated protection.
+
+T04/T05/T06 remain progress: independent caller/template/tenant admission, limits,
+caller-scoped status, platform sender and independent ledger backup custody,
+inbound/reply/bounce ownership, alignment/retention and isolated issuer/mailbox/app
+browser journeys still need owner returns. EMAIL-WP-0007-T03/T04 and
+RPF-WP-0053-T05 remain the live ledger custody/activation handoffs. No external
+owner source/runtime, mailbox access, caller admission or email send changed;
+no productive new communication flow was accepted or this workplan finished.