CVE-2026-47715

@@ -441,6 +441,29 @@ def test_issue_details(self):
         response = self.client.get(f"/issues/issue/{self.issue.id}/event/{self.event.id}/details/")
         self.assertContains(response, self.issue.title())
 
+    def test_issue_event_views_do_not_show_events_from_other_projects(self):
+        other_project = Project.objects.create(name="other")
+        other_issue, _ = get_or_create_issue(other_project)
+        other_event = create_event(other_project, other_issue, event_data={
+            "event_id": uuid.uuid4().hex,
+            "timestamp": datetime.now(timezone.utc).isoformat(),
+            "platform": "python",
+            "exception": {"values": [{"type": "OtherProjectError", "value": "other project stack value"}]},
+            "request": {"headers": {"X-Secret": "other-project-header-value"}},
+            "breadcrumbs": {"values": [{"category": "other-project", "message": "other project breadcrumb"}]},
+        })
+
+        cases = [
+            (f"/issues/issue/{self.issue.id}/event/{other_event.id}/", "other project stack value"),
+            (f"/issues/issue/{self.issue.id}/event/{other_event.id}/details/", "other-project-header-value"),
+            (f"/issues/issue/{self.issue.id}/event/{other_event.id}/breadcrumbs/", "other project breadcrumb"),
+        ]
+        for url, marker in cases:
+            with self.subTest(url=url):
+                response = self.client.get(url)
+                self.assertEqual(response.status_code, 200)
+                self.assertNotContains(response, marker)
+
     def test_issue_tags(self):
         response = self.client.get(f"/issues/issue/{self.issue.id}/tags/")
         self.assertContains(response, self.issue.title())

@@ -422,11 +422,12 @@ def _get_event(qs, issue, event_pk, digest_order, nav, bounds):
     elif event_pk is not None:
         # we match on both internal and external id, trying internal first
         try:
-            return Event.objects.get(pk=event_pk)
+            return Event.objects.get(issue=issue, pk=event_pk)
         except Event.DoesNotExist:
             # we match on external id "for user ergonomics"; notes as in `event_by_id` apply, except for the fact that
-            # in this case we have project availab, guaranteeing uniqueness & fast lookup.
-            return Event.objects.get(project=issue.project, event_id=event_pk)
+            # in this case we have the project available, guaranteeing uniqueness & fast lookup.
+            # We also filter by issue to guarantee we do not escape the URL's issue scope.
+            return Event.objects.get(project=issue.project, issue=issue, event_id=event_pk)
 
     elif digest_order is not None:
         # "ergonomics" when people type this in the URL bar

@@ -4,7 +4,7 @@
 from sentry_sdk_extensions import capture_or_log_exception
 
 from bugsink.utils import assert_
-from .models import FileMetadata
+from .models import get_file_metadata_for_debug_id
 
 
 def get_single_object(archive):
@@ -15,7 +15,7 @@ def get_single_object(archive):
     return objects[0]
 
 
-def build_cfi_map_from_minidump_bytes(minidump_bytes):
+def build_cfi_map_from_minidump_bytes(minidump_bytes, project):
     process_state = symbolic.minidump.ProcessState.from_minidump_buffer(minidump_bytes)
 
     frame_info_map = symbolic.minidump.FrameInfoMap.new()
@@ -25,10 +25,11 @@ def build_cfi_map_from_minidump_bytes(minidump_bytes):
             continue
 
         dashed_debug_id = symbolic.debuginfo.id_from_breakpad(module.debug_id)
-        if FileMetadata.objects.filter(debug_id=dashed_debug_id, file_type="dbg").count() == 0:
+        file_metadata = get_file_metadata_for_debug_id(project, dashed_debug_id, "dbg")
+        if file_metadata is None:
             continue
 
-        dif_bytes = FileMetadata.objects.get(debug_id=dashed_debug_id, file_type="dbg").file.get_raw_data()
+        dif_bytes = file_metadata.file.get_raw_data()
         archive = symbolic.debuginfo.Archive.from_bytes(dif_bytes)
 
         debug_object = get_single_object(archive)
@@ -86,7 +87,7 @@ def _find_module_for_address(process_state, abs_addr: int):
     return None
 
 
-def event_threads_for_process_state(process_state):
+def event_threads_for_process_state(process_state, project):
     threads = []
     for thread_index, symbolic_thread in enumerate(process_state.threads()):
         frames = []
@@ -99,7 +100,7 @@ def event_threads_for_process_state(process_state):
             if module and module.debug_id:
                 dashed_debug_id = symbolic.debuginfo.id_from_breakpad(module.debug_id)
 
-                file_metadata = FileMetadata.objects.filter(debug_id=dashed_debug_id, file_type="dbg").first()
+                file_metadata = get_file_metadata_for_debug_id(project, dashed_debug_id, "dbg")
                 if file_metadata:
                     dif_bytes = file_metadata.file.get_raw_data()
 
@@ -121,7 +122,7 @@ def event_threads_for_process_state(process_state):
                             frame["filename"] = line_info.filename
                         frame["lineno"] = line_info.line
 
-                        src_meta = FileMetadata.objects.filter(debug_id=dashed_debug_id, file_type="src").first()
+                        src_meta = get_file_metadata_for_debug_id(project, dashed_debug_id, "src")
                         if src_meta and line_info.filename and line_info.line:
                             frame["pre_context"], frame["context_line"], frame["post_context"] = extract_source_context(
                                 src_meta.file.get_raw_data(), line_info.filename, line_info.line)

@@ -10,6 +10,7 @@
 import subprocess
 import tempfile
 from pathlib import Path
+from types import SimpleNamespace
 from zipfile import ZipFile, ZIP_DEFLATED
 
 from django.test import tag
@@ -30,6 +31,7 @@
 from bugsink.streams import MaxLengthExceeded
 
 from .models import Chunk, File, FileMetadata, get_file_metadata_for_debug_ids
+from .minidump import event_threads_for_process_state
 from .storage_registry import override_object_storages
 from .tasks import assemble_file
 from .views import CHUNK_UPLOAD_SIZE
@@ -449,6 +451,85 @@ def test_get_file_metadata_for_debug_ids_uses_project_scope_before_legacy_fallba
         self.assertEqual(scoped_metadata, result[scoped_debug_id])
         self.assertEqual(legacy_metadata, result[legacy_debug_id])
 
+    @patch("files.views.extract_dif_metadata")
+    def test_difs_assemble_stores_project_scoped_metadata(self, mock_extract_dif_metadata):
+        debug_id = uuid4()
+        data = b"debug"
+        checksum = sha1(data, usedforsecurity=False).hexdigest()
+        Chunk.objects.create(checksum=checksum, size=len(data), data=data)
+        mock_extract_dif_metadata.return_value = {"kind": "dbg"}
+
+        with bugsink_override_settings(FEATURE_MINIDUMPS=True):
+            response = self.client.post(
+                f"/api/0/projects/anyorg/{self.project.slug}/files/difs/assemble/",
+                json.dumps({
+                    checksum: {
+                        "chunks": [checksum],
+                        "debug_id": str(debug_id),
+                        "name": "debug-file",
+                    },
+                }),
+                content_type="application/json",
+                headers=self.token_headers,
+            )
+
+        self.assertEqual(200, response.status_code)
+        metadata = FileMetadata.objects.get(debug_id=debug_id, file_type="dbg")
+        self.assertEqual(self.project, metadata.project)
+        self.assertEqual("debug-file", metadata.file.filename)
+
+    @patch("files.minidump.extract_source_context")
+    @patch("files.minidump.symbolic.debuginfo.Archive.from_bytes")
+    @patch("files.minidump.symbolic.debuginfo.id_from_breakpad")
+    def test_minidump_symbolication_uses_project_scoped_debug_files(
+        self,
+        mock_id_from_breakpad,
+        mock_archive_from_bytes,
+        mock_extract_source_context,
+    ):
+        debug_id = uuid4()
+        other_project = Project.objects.create(name="other")
+        dbg_file = File.objects.create(checksum="d" * 40, filename="debug-file", size=0, data=b"debug")
+        src_file = File.objects.create(checksum="e" * 40, filename="source-bundle", size=0, data=b"source")
+
+        FileMetadata.objects.create(project=other_project, debug_id=debug_id, file_type="dbg", file=dbg_file)
+        FileMetadata.objects.create(project=other_project, debug_id=debug_id, file_type="src", file=src_file)
+
+        line_info = SimpleNamespace(function_name="otherFunction", filename="other.c", line=7)
+        symcache = SimpleNamespace(lookup=lambda rel: [line_info])
+        debug_object = SimpleNamespace(make_symcache=lambda: symcache)
+        archive = SimpleNamespace(iter_objects=lambda: [debug_object])
+        mock_id_from_breakpad.return_value = str(debug_id)
+        mock_archive_from_bytes.return_value = archive
+        mock_extract_source_context.return_value = (["pre"], "context", ["post"])
+
+        module = SimpleNamespace(addr=1000, size=100, debug_id="breakpad-debug-id")
+        frame = SimpleNamespace(instruction=1010)
+        thread = SimpleNamespace(thread_id=1, frames=lambda: [frame])
+        process_state = SimpleNamespace(
+            modules=lambda: [module],
+            threads=lambda: [thread],
+            requesting_thread=0,
+        )
+
+        # Positive case: the debug files work for the project they were uploaded to.
+        threads = event_threads_for_process_state(process_state, other_project)
+        rendered_frame = threads[0]["stacktrace"]["frames"][0]
+        self.assertEqual("otherFunction", rendered_frame["function"])
+        self.assertEqual("other.c", rendered_frame["filename"])
+        self.assertEqual(7, rendered_frame["lineno"])
+        self.assertEqual("context", rendered_frame["context_line"])
+
+        # Negative case: the same debug ID does not resolve across project boundaries.
+        mock_archive_from_bytes.reset_mock()
+        mock_extract_source_context.reset_mock()
+
+        threads = event_threads_for_process_state(process_state, self.project)
+        rendered_frame = threads[0]["stacktrace"]["frames"][0]
+        self.assertEqual({"instruction_addr": "0x3f2"}, rendered_frame)
+        mock_archive_from_bytes.assert_not_called()
+        mock_extract_source_context.assert_not_called()
+
     @tag("samples")
     def test_assemble_artifact_bundle(self):
         SAMPLES_DIR = os.getenv("SAMPLES_DIR", "../event-samples")

@@ -263,6 +263,10 @@ def difs_assemble(request, organization_slug, project_slug):
     if not get_settings().FEATURE_MINIDUMPS:
         return JsonResponse({"detail": "minidumps not enabled"}, status=404)
 
+    project = Project.objects.filter(slug=project_slug, is_deleted=False).first()
+    if project is None:
+        return JsonResponse({"detail": "Project not found: %s" % project_slug}, status=404)
+
     # TODO move to tasks.something.delay
     # TODO think about the right transaction around this
     data = json.loads(request.body)
@@ -288,39 +292,33 @@ def difs_assemble(request, organization_slug, project_slug):
 
     for file_checksum, file_info in data.items():
         if file_checksum in existing_files:
-            response[file_checksum] = {
-                "state": ChunkFileState.OK,
-                "missingChunks": [],
-                # if it is ever needed, we could add something akin to the below, but so far we've not seen client-side
-                # actually using this; let's add it on-demand.
-                # "dif": json_repr_with_key_info_about(existing_files[file_checksum]),
-            }
-            continue
-
-        file_chunks = file_info.get("chunks", [])
-
-        # the sentry-cli sends an empty "chunks" list when just polling for file existence; since we already handled the
-        # case of existing files above, we can simply return NOT_FOUND here.
-        if not file_chunks:
-            response[file_checksum] = {
-                "state": ChunkFileState.NOT_FOUND,
-                "missingChunks": [],
-            }
-            continue
-
-        missing_chunks = [c for c in file_chunks if c not in available_chunks]
-        if missing_chunks:
-            response[file_checksum] = {
-                "state": ChunkFileState.NOT_FOUND,
-                "missingChunks": missing_chunks,
-            }
-            continue
-
-        file, _ = assemble_file(file_checksum, file_chunks, filename=file_info["name"])
+            file = existing_files[file_checksum]
+        else:
+            file_chunks = file_info.get("chunks", [])
+
+            # the sentry-cli sends an empty "chunks" list when just polling for file existence; since we already handled
+            # the case of existing files above, we can simply return NOT_FOUND here.
+            if not file_chunks:
+                response[file_checksum] = {
+                    "state": ChunkFileState.NOT_FOUND,
+                    "missingChunks": [],
+                }
+                continue
+
+            missing_chunks = [c for c in file_chunks if c not in available_chunks]
+            if missing_chunks:
+                response[file_checksum] = {
+                    "state": ChunkFileState.NOT_FOUND,
+                    "missingChunks": missing_chunks,
+                }
+                continue
+
+            file, _ = assemble_file(file_checksum, file_chunks, filename=file_info["name"])
 
         symbolic_metadata = extract_dif_metadata(file.get_raw_data())
 
         FileMetadata.objects.get_or_create(
+            project=project,
             debug_id=file_info.get("debug_id"),  # TODO : .get implies "no debug_id", but in that case it's useless
             file_type=symbolic_metadata["kind"],  # NOTE: symbolic's kind goes into file_type...
             defaults={

@@ -248,7 +248,7 @@ def process_minidump(cls, ingested_at, ingestion_id, minidump_bytes, project, re
         event_data["platform"] = "native"
         event_data["errors"] = []
 
-        merge_minidump_event(event_data, minidump_bytes)
+        merge_minidump_event(event_data, minidump_bytes, project)
 
         # write the event data to disk:
         filename = get_filename_for_event_id(ingestion_id)
@@ -374,7 +374,7 @@ def digest_event(cls, event_metadata, event_data, digested_at=None, minidump_byt
             # we merge after validation: validation is about what's provided _externally_, not our own merging.
             # TODO error handling
             # TODO should not be inside immediate_atomic if it turns out to be slow
-            merge_minidump_event(event_data, minidump_bytes)
+            merge_minidump_event(event_data, minidump_bytes, project)
 
         # I resisted the temptation to put `get_denormalized_fields_for_data` in an if-statement: you basically "always"
         # need this info... except when duplicate event-ids are sent. But the latter is the exception, and putting this

@@ -6,8 +6,8 @@
 from files.minidump import build_cfi_map_from_minidump_bytes, event_threads_for_process_state
 
 
-def merge_minidump_event(data, minidump_bytes):
-    frame_info_map = build_cfi_map_from_minidump_bytes(minidump_bytes)
+def merge_minidump_event(data, minidump_bytes, project):
+    frame_info_map = build_cfi_map_from_minidump_bytes(minidump_bytes, project)
     process_state = symbolic.ProcessState.from_minidump_buffer(minidump_bytes, frame_infos=frame_info_map)
 
     data['level'] = 'fatal' if process_state.crashed else 'info'
@@ -26,7 +26,7 @@ def merge_minidump_event(data, minidump_bytes):
     os['version'] = info.os_version
     device['arch'] = info.cpu_family
 
-    threads = event_threads_for_process_state(process_state)
+    threads = event_threads_for_process_state(process_state, project)
     data.setdefault("threads", {})["values"] = threads
 
     if process_state.requesting_thread > -1:

@@ -136,7 +136,7 @@ def _select_frames(frames, in_app_only):
 def render_stacktrace_md(event, in_app_only=False, include_locals=True):
     parsed = event.get_parsed_data()
     try:
-        apply_sourcemaps(parsed)
+        apply_sourcemaps(parsed, event.project)
     except Exception as e:
         if settings.DEBUG or settings.I_AM_RUNNING == "TEST":
             # when developing/testing, I _do_ want to get notified

@@ -10,7 +10,7 @@
 
 from compat.timestamp import format_timestamp
 
-from files.models import FileMetadata
+from files.models import get_file_metadata_for_debug_ids
 from files.tasks import record_file_accesses
 
 
@@ -113,7 +113,7 @@ def _postgres_fix(memoryview_or_bytes):
     return memoryview_or_bytes
 
 
-def apply_sourcemaps(event_data):
+def apply_sourcemaps(event_data, project):
     images = event_data.get("debug_meta", {}).get("images", [])
     if not images:
         return
@@ -124,11 +124,7 @@ def apply_sourcemaps(event_data):
         if "debug_id" in image and "code_file" in image and image["type"] == "sourcemap"
     }
 
-    metadata_obj_lookup = {
-        metadata_obj.debug_id: metadata_obj
-        for metadata_obj in FileMetadata.objects.filter(
-            debug_id__in=debug_id_for_filename.values(), file_type="source_map").select_related("file")
-    }
+    metadata_obj_lookup = get_file_metadata_for_debug_ids(project, debug_id_for_filename.values(), "source_map")
 
     metadata_ids = [metadata_obj.id for metadata_obj in metadata_obj_lookup.values()]
     delay_on_commit(record_file_accesses, metadata_ids, format_timestamp(datetime.now(timezone.utc)))
@@ -190,7 +186,7 @@ def apply_sourcemaps(event_data):
                 frame["debug_id"] = str(debug_id_for_filename[frame["filename"]])
 
 
-def get_sourcemap_images(event_data):
+def get_sourcemap_images(event_data, project):
     # NOTE: butchered copy/paste of apply_sourcemaps; refactoring for DRY is a TODO
     images = event_data.get("debug_meta", {}).get("images", [])
     if not images:
@@ -202,11 +198,7 @@ def get_sourcemap_images(event_data):
         if "debug_id" in image and "code_file" in image and image["type"] == "sourcemap"
     }
 
-    metadata_obj_lookup = {
-        metadata_obj.debug_id: metadata_obj
-        for metadata_obj in FileMetadata.objects.filter(
-            debug_id__in=debug_id_for_filename.values(), file_type="source_map").select_related("file")
-    }
+    metadata_obj_lookup = get_file_metadata_for_debug_ids(project, debug_id_for_filename.values(), "source_map")
 
     return [
         (basename(filename),

@@ -27,6 +27,6 @@ def download_link(self, obj):
 
 @admin.register(FileMetadata)
 class FileMetadataAdmin(admin.ModelAdmin):
-    list_display = ('debug_id', 'file_type', 'file', 'created_at')
-    search_fields = ('file__checksum', 'debug_id', 'file_type')
-    readonly_fields = ('file', 'debug_id', 'file_type', 'data', 'created_at')
+    list_display = ('debug_id', 'file_type', 'project', 'file', 'created_at')
+    search_fields = ('file__checksum', 'debug_id', 'file_type', 'project__name', 'project__slug')
+    readonly_fields = ('file', 'project', 'debug_id', 'file_type', 'data', 'created_at')

@@ -0,0 +1,30 @@
+from django.core.management.base import BaseCommand
+
+from bugsink.transaction import immediate_atomic
+from files.models import File, FileMetadata
+
+
+class Command(BaseCommand):
+    """Delete projectless sourcemaps kept only for the project-scoping transition.
+
+    After sourcemap metadata became project-scoped, old projectless metadata
+    still works as a compatibility fallback. Run this command when you prefer
+    to remove that fallback immediately and force sourcemaps to be re-uploaded
+    with explicit project slugs.
+    """
+
+    help = "Delete legacy projectless sourcemaps."
+
+    def handle(self, *args, **options):
+        with immediate_atomic():
+            legacy_metadata = FileMetadata.objects.filter(project__isnull=True, file_type="source_map")
+            file_ids = list(legacy_metadata.values_list("file_id", flat=True))
+            metadata_count = legacy_metadata.count()
+
+            legacy_metadata.delete()
+
+            orphan_files = File.objects.filter(id__in=file_ids, metadatas__isnull=True)
+            file_count = orphan_files.count()
+            orphan_files.delete()
+
+        self.stdout.write(f"Deleted {metadata_count} legacy sourcemap metadata rows and {file_count} files.")

@@ -0,0 +1,32 @@
+# Generated by Django 5.2.12 on 2026-05-19 07:49
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('files', '0003_file_storage_backend'),
+        ('projects', '0017_project_issue_count'),
+    ]
+
+    operations = [
+        migrations.AlterUniqueTogether(
+            name='filemetadata',
+            unique_together=set(),
+        ),
+        migrations.AddField(
+            model_name='filemetadata',
+            name='project',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, to='projects.project'),
+        ),
+        migrations.AddConstraint(
+            model_name='filemetadata',
+            constraint=models.UniqueConstraint(condition=models.Q(('debug_id__isnull', False), ('file_type__isnull', False), ('project__isnull', False)), fields=('project', 'debug_id', 'file_type'), name='filemeta_project_debug_type'),
+        ),
+        migrations.AddConstraint(
+            model_name='filemetadata',
+            constraint=models.UniqueConstraint(condition=models.Q(('debug_id__isnull', False), ('file_type__isnull', False), ('project__isnull', True)), fields=('debug_id', 'file_type'), name='filemeta_legacy_debug_type'),
+        ),
+    ]

@@ -3,6 +3,7 @@
 from io import BytesIO
 from django.db import models
 from django.db import transaction
+from django.db.models import Q
 
 from functools import partial
 
@@ -137,6 +138,11 @@ def _cleanup_objects_on_storage(todos):
 class FileMetadata(models.Model):
     file = models.ForeignKey(File, null=False, on_delete=models.CASCADE, related_name="metadatas")
 
+    # FileMetadata as provided by the client (e.g. in a manifest); security-wise any facts noted here are not guaranteed
+    # to be correct / cannot be trusted. Our security boundary is: FileMetadata is bound to a Project, so you can only
+    # pollute your own Project's FileMetadata.
+    project = models.ForeignKey("projects.Project", null=True, blank=True, on_delete=models.CASCADE)
+
     # debug_id & file_type nullability: such data exists in manifest.json; we are future-proof for it although we
     # currently don't store it as such.
     debug_id = models.UUIDField(max_length=40, null=True, blank=True)
@@ -149,7 +155,64 @@ def __str__(self):
         return f"debug_id: {self.debug_id} ({self.file_type})"
 
     class Meta:
-        # it's _imaginable_ that the below does not actually hold (we just trust the CLI, after all), but that wouldn't
-        # make any sense, so we just enforce a property that makes sense. Pro: lookups work. Con: if the client sends
-        # garbage, this is not exposed.
-        unique_together = (("debug_id", "file_type"),)
+        # The below is basically the ["project", "debug_id", "file_type"] uniqueness constraint we want, but with a
+        # twist to allow legacy data without project. We can remove the legacy constraint after a long transition
+        # period, e.g. May 2027, at which point the first constraint can be simplified to a normal uniqueness constraint
+        # on the three fields. (just the single unique_together constraint doesn't work because of the nullability of
+        # project, which would allow multiple entries with the same debug_id and file_type but null project because
+        # nulls are not considered equal in SQL)
+        constraints = [
+            models.UniqueConstraint(
+                fields=["project", "debug_id", "file_type"],
+                condition=Q(project__isnull=False, debug_id__isnull=False, file_type__isnull=False),
+                name="filemeta_project_debug_type",
+            ),
+            models.UniqueConstraint(
+                fields=["debug_id", "file_type"],
+                condition=Q(project__isnull=True, debug_id__isnull=False, file_type__isnull=False),
+                name="filemeta_legacy_debug_type",
+            ),
+        ]
+
+
+def get_file_metadata_for_debug_ids(project, debug_ids, file_type):
+    """Return {debug_id: FileMetadata} for debug files visible to project."""
+    debug_ids = set(debug_ids)
+    if not debug_ids:
+        return {}
+
+    result = {
+        metadata.debug_id: metadata
+        for metadata in FileMetadata.objects.filter(
+            project=project,
+            debug_id__in=debug_ids,
+            file_type=file_type,
+        ).select_related("file")
+    }
+
+    missing_debug_ids = debug_ids - set(result)
+    if missing_debug_ids:
+        # Compatibility for sourcemaps/debug files uploaded before project-scoped metadata existed. This keeps old
+        # installs working for now, but should be removed after a long transition period, e.g. May 2027.
+        result.update({
+            metadata.debug_id: metadata
+            for metadata in FileMetadata.objects.filter(
+                project__isnull=True,
+                debug_id__in=missing_debug_ids,
+                file_type=file_type,
+            ).select_related("file")
+        })
+
+    return result
+
+
+def get_file_metadata_for_debug_id(project, debug_id, file_type):
+    result = list(get_file_metadata_for_debug_ids(project, [debug_id], file_type).values())
+    if len(result) == 0:
+        return None
+
+    if len(result) > 1:
+        # Should be prevented by database constraints; getting here would mean our lookup logic is wrong.
+        raise RuntimeError("Multiple FileMetadata objects found for one debug_id")
+
+    return result[0]

@@ -109,7 +109,7 @@ def find_in_code_debug_ids(local_file):
 
 
 @shared_task
-def assemble_artifact_bundle(bundle_checksum, chunk_checksums):
+def assemble_artifact_bundle(bundle_checksum, chunk_checksums, project_ids):
     # arguably, you could just wrap-around each operation, "around everything" guarantees a fully consistent update on
     # the data and we don't do this that often that it's assumed to matter.
     with immediate_atomic():
@@ -119,6 +119,7 @@ def assemble_artifact_bundle(bundle_checksum, chunk_checksums):
         # support that, but if we ever were to support it we'd need a separate method/param to distinguish it.
 
         bundle_file, _ = assemble_file(bundle_checksum, chunk_checksums, filename=f"{bundle_checksum}.zip")
+
         max_file_size = get_settings().MAX_FILE_SIZE
         with tempfile.TemporaryDirectory() as tempdir:
             with bundle_file.open_for_read() as f:
@@ -153,14 +154,16 @@ def assemble_artifact_bundle(bundle_checksum, chunk_checksums):
 
                                 continue
 
-                            FileMetadata.objects.get_or_create(
-                                debug_id=debug_id,
-                                file_type=file_type,
-                                defaults={
-                                    "file": file,
-                                    "data": json.dumps(manifest_entry),
-                                }
-                            )
+                            for project_id in project_ids:
+                                FileMetadata.objects.get_or_create(
+                                    project_id=project_id,
+                                    debug_id=debug_id,
+                                    file_type=file_type,
+                                    defaults={
+                                        "file": file,
+                                        "data": json.dumps(manifest_entry),
+                                    }
+                                )
 
                             # the in-code regexes show up in the _minified_ source only (the sourcemap's original source
                             # code will not have been "polluted" with it yet, since it's the original).
@@ -188,7 +191,11 @@ def assemble_file(checksum, chunk_checksums, filename):
     # NOTE: unimplemented checks/tricks
     # * total file-size v.s. some max
     # * explicit check chunk availability
-    # * skip this whole thing when the (whole-file) checksum exists
+
+    try:
+        return File.objects.get(checksum=checksum), False
+    except File.DoesNotExist:
+        pass  # i.e. continue below
 
     chunks = Chunk.objects.filter(checksum__in=chunk_checksums)
     chunks_dicts = {chunk.checksum: chunk for chunk in chunks}

@@ -29,7 +29,7 @@
 from bugsink.app_settings import override_settings as bugsink_override_settings
 from bugsink.streams import MaxLengthExceeded
 
-from .models import Chunk, File, FileMetadata
+from .models import Chunk, File, FileMetadata, get_file_metadata_for_debug_ids
 from .storage_registry import override_object_storages
 from .tasks import assemble_file
 from .views import CHUNK_UPLOAD_SIZE
@@ -58,7 +58,7 @@ class FilesTests(TransactionTestCase):
     def setUp(self):
         super().setUp()
         self.user = User.objects.create_user(username='test', password='test')
-        self.project = Project.objects.create()
+        self.project = Project.objects.create(name="test")
         ProjectMembership.objects.create(project=self.project, user=self.user)
         self.client.force_login(self.user)
         self.auth_token = AuthToken.objects.create()
@@ -206,7 +206,7 @@ def test_artifact_bundle_rejects_extracted_file_larger_than_max_file_size(self):
                     with self.assertRaises(MaxLengthExceeded):
                         self.client.post(
                             "/api/0/organizations/anyorg/artifactbundle/assemble/",
-                            json.dumps({"checksum": checksum, "chunks": [checksum], "projects": ["unused"]}),
+                            json.dumps({"checksum": checksum, "chunks": [checksum], "projects": [self.project.slug]}),
                             content_type="application/json",
                             headers=self.token_headers,
                         )
@@ -222,7 +222,11 @@ def test_artifact_bundle_assemble_does_not_use_checksum_as_temp_filename(self):
             try:
                 self.client.post(
                     "/api/0/organizations/anyorg/artifactbundle/assemble/",
-                    json.dumps({"checksum": str(probe_path), "chunks": [real_checksum], "projects": ["unused"]}),
+                    json.dumps({
+                        "checksum": str(probe_path),
+                        "chunks": [real_checksum],
+                        "projects": [self.project.slug],
+                    }),
                     content_type="application/json",
                     headers=self.token_headers,
                 )
@@ -421,6 +425,30 @@ def test_uuid_behavior_of_django(self):
                 fms = FileMetadata.objects.filter(debug_id__in=[test_with])
                 self.assertEqual(1, fms.count())
 
+    def test_get_file_metadata_for_debug_ids_uses_project_scope_before_legacy_fallback(self):
+        scoped_debug_id = uuid4()
+        legacy_debug_id = uuid4()
+        file = File.objects.create(checksum="a" * 40, filename="scoped.js.map", size=0)
+        legacy_file = File.objects.create(checksum="b" * 40, filename="legacy.js.map", size=0)
+
+        scoped_metadata = FileMetadata.objects.create(
+            project=self.project,
+            debug_id=scoped_debug_id,
+            file_type="source_map",
+            file=file,
+        )
+        FileMetadata.objects.create(debug_id=scoped_debug_id, file_type="source_map", file=legacy_file)
+        legacy_metadata = FileMetadata.objects.create(debug_id=legacy_debug_id, file_type="source_map", file=file)
+
+        result = get_file_metadata_for_debug_ids(
+            self.project,
+            [scoped_debug_id, legacy_debug_id],
+            "source_map",
+        )
+
+        self.assertEqual(scoped_metadata, result[scoped_debug_id])
+        self.assertEqual(legacy_metadata, result[legacy_debug_id])
+
     @tag("samples")
     def test_assemble_artifact_bundle(self):
         SAMPLES_DIR = os.getenv("SAMPLES_DIR", "../event-samples")
@@ -461,7 +489,7 @@ def test_assemble_artifact_bundle(self):
                     checksum,  # single-chunk upload, so this works
                 ],
                 "projects": [
-                    "unused_for_now"
+                    self.project.slug
                 ]
             }
 
@@ -551,7 +579,7 @@ def test_assemble_artifact_bundle_small_chunks(self):
             "checksum": checksum,
             "chunks": seen_checksums,
             "projects": [
-                "unused_for_now"
+                self.project.slug
             ]
         }
 
@@ -587,6 +615,7 @@ def setUp(self):
         super().setUp()
         auth = AuthToken.objects.create(description="test token")
         self.token = auth.token
+        self.project = Project.objects.create(name="test")
 
         # sentry-cli asks _us_ for our own URL...
         self.enterContext(bugsink_override_settings(BASE_URL=self.live_server_url))
@@ -597,7 +626,7 @@ def setUp(self):
         self.enterContext(override_settings(DEBUG_PROPAGATE_EXCEPTIONS=True))
         self.tempdir = self.enterContext(tempfile.TemporaryDirectory())
 
-    def _run(self, args):
+    def _run(self, args, expect_success=True):
         sp = subprocess.run(
             args,
             cwd=self.tempdir,
@@ -608,8 +637,12 @@ def _run(self, args):
             stdout=subprocess.PIPE,
             stderr=subprocess.STDOUT,  # merge stderr into stdout so we can see it in test failures
         )
-        if sp.returncode != 0:
-            raise Exception(f"Command {args} failed with output:\n{sp.stdout.decode('utf-8')}")
+        output = sp.stdout.decode('utf-8')
+        if expect_success and sp.returncode != 0:
+            raise Exception(f"Command {args} failed with output:\n{output}")
+        if not expect_success and sp.returncode == 0:
+            raise Exception(f"Command {args} unexpectedly succeeded with output:\n{output}")
+        return output
 
     def test_sentry_cli_upload(self):
         # Test-the-test (these things should live in your env, as per requirements.development.txt)
@@ -647,7 +680,7 @@ def test_sentry_cli_upload(self):
             "--org",
             "bugsinkhasnoorgs",
             "--project",
-            "ignoredfornow",
+            self.project.slug,
             "upload",
             str(map_path),
         ])
@@ -660,6 +693,50 @@ def test_sentry_cli_upload(self):
         self.assertEqual(
             UUID('9b40e0f3-8084-5931-94d4-8d941780a177'),
             FileMetadata.objects.get(file__filename="captureException.js.map").debug_id)
+        self.assertEqual(self.project, FileMetadata.objects.get(file__filename="captureException.js.map").project)
+
+        # sentry-cli sourcemaps upload with bogus project
+        output = self._run([
+            sentry_cli,
+            "--log-level=debug",
+            "--url",
+            self.live_server_url,
+            "sourcemaps",
+            "--org",
+            "bugsinkhasnoorgs",
+            "--project",
+            "intentionallynonexistentproject",
+            "upload",
+            str(map_path),
+        ], expect_success=False)
+        self.assertIn("Unknown project(s): intentionallynonexistentproject", output)
+
+        # sentry-cli sourcemaps upload with multiple projects
+        other_project = Project.objects.create(name="other")
+        self._run([
+            sentry_cli,
+            "--log-level=debug",
+            "--url",
+            self.live_server_url,
+            "sourcemaps",
+            "--org",
+            "bugsinkhasnoorgs",
+            "--project",
+            self.project.slug,
+            "--project",
+            other_project.slug,
+            "upload",
+            str(map_path),
+        ])
+
+        self.assertEqual(
+            {self.project.id, other_project.id},
+            set(
+                FileMetadata.objects
+                .filter(file__filename="captureException.js.map")
+                .values_list("project", flat=True)
+            ),
+        )
 
 
 MINIMAL_JS = """\

@@ -15,6 +15,7 @@
 from bugsink.transaction import durable_atomic, immediate_atomic
 from bugsink.streams import handle_request_content_encoding, copy_stream_limited, MaxLengthExceeded
 from bsmain.models import AuthToken
+from projects.models import Project
 
 from .models import Chunk, File, FileMetadata
 from .tasks import assemble_artifact_bundle, assemble_file
@@ -26,6 +27,10 @@
 _KIBIBYTE = 1024
 _MEBIBYTE = 1024 * _KIBIBYTE
 CHUNK_UPLOAD_SIZE = 2 * _MEBIBYTE
+PROJECT_REQUIRED_MESSAGE = (
+    "Starting with Bugsink 2.2.0, sourcemap uploads must name existing Bugsink project slugs. "
+    "Use sentry-cli --project <project-slug>."
+)
 
 
 def get_chunk_upload_settings(request, organization_slug):
@@ -135,6 +140,23 @@ def first_require_auth_token(request, *args, **kwargs):
     return first_require_auth_token
 
 
+def get_artifact_bundle_projects(data):
+    project_slugs = data.get("projects") or []
+    if not isinstance(project_slugs, list):
+        return None, PROJECT_REQUIRED_MESSAGE
+
+    if not project_slugs:
+        return None, PROJECT_REQUIRED_MESSAGE
+
+    projects = list(Project.objects.filter(slug__in=project_slugs, is_deleted=False))
+    projects_by_slug = {project.slug: project for project in projects}
+    unknown_slugs = sorted(set(project_slugs) - set(projects_by_slug))
+    if unknown_slugs:
+        return None, PROJECT_REQUIRED_MESSAGE + " Unknown project(s): %s." % ", ".join(unknown_slugs)
+
+    return [projects_by_slug[slug] for slug in dict.fromkeys(project_slugs)], None
+
+
 @csrf_exempt
 @requires_auth_token
 def chunk_upload(request, organization_slug):
@@ -214,6 +236,9 @@ def artifact_bundle_assemble(request, organization_slug):
     data = json.loads(request.body)
     checksum = data["checksum"]
     chunk_checksums = data["chunks"]
+    projects, error = get_artifact_bundle_projects(data)
+    if error is not None:
+        return JsonResponse({"error": error}, status=400)
 
     # sentry-cli >= 3.x calls this endpoint before uploading chunks (to learn which ones are missing), then uploads
     # only the missing chunks, and then polls this endpoint again. We must return the actual missing chunks; returning
@@ -226,7 +251,7 @@ def artifact_bundle_assemble(request, organization_slug):
     if missing_chunks:
         return JsonResponse({"state": ChunkFileState.NOT_FOUND, "missingChunks": missing_chunks})
 
-    assemble_artifact_bundle.delay(checksum, chunk_checksums)
+    assemble_artifact_bundle.delay(checksum, chunk_checksums, [project.id for project in projects])
     # In the ALWAYS_EAGER setup, we process the bundle inline, so arguably we could return "OK" here too; "CREATED" is
     # what sentry returns though, so for faithful mimicking it's the safest bet.
     return JsonResponse({"state": ChunkFileState.CREATED, "missingChunks": []})

@@ -4,11 +4,13 @@
 import uuid
 import json
 import hashlib
-from io import StringIO
+import gzip
+from io import BytesIO, StringIO
 from glob import glob
 from unittest import TestCase as RegularTestCase
 from unittest.mock import patch
 from datetime import datetime, timezone
+from zipfile import ZIP_DEFLATED, ZipFile
 
 from django.test import TestCase as DjangoTestCase
 from django.contrib.auth import get_user_model
@@ -24,6 +26,7 @@
 from bsmain.management.commands.send_json import Command as SendJsonCommand
 from compat.dsn import get_header_value
 from events.models import Event
+from bsmain.models import AuthToken
 from ingest.views import BaseIngestAPIView
 from issues.factories import get_or_create_issue
 from tags.models import store_tags
@@ -407,7 +410,7 @@ class ViewTests(TransactionTestCase):
     def setUp(self):
         super().setUp()
         self.user = User.objects.create_user(username='test', password='test')
-        self.project = Project.objects.create()
+        self.project = Project.objects.create(name="test")
         ProjectMembership.objects.create(project=self.project, user=self.user)
         self.issue, _ = get_or_create_issue(self.project)
         self.event = create_event(self.project, self.issue, project_digest_order=1)
@@ -607,6 +610,96 @@ def lookup_left(self, line, column):
         self.assertContains(response, "good-source.ts")
         self.assertContains(response, "mappedFunction</span> line <span class=\"font-bold\">11</span>")
 
+    @patch("events.utils.ecma426.loads")
+    def test_sourcemap_uploads_are_project_scoped_when_rendering_events(self, mock_ecma426_loads):
+        debug_id = uuid.uuid4()
+        auth_token = AuthToken.objects.create()
+        other_project = Project.objects.create(name="other")
+        ProjectMembership.objects.create(project=other_project, user=self.user)
+        other_issue, _ = get_or_create_issue(other_project)
+        sourcemap = json.dumps({
+            "version": 3,
+            "sources": ["other-project-source.ts"],
+            "sourcesContent": ["other project source"],
+            "names": [],
+            "mappings": "",
+        })
+        bundle = BytesIO()
+        with ZipFile(bundle, "w", compression=ZIP_DEFLATED) as zf:
+            zf.writestr("manifest.json", json.dumps({
+                "files": {
+                    "~/app.js.map": {
+                        "url": "~/app.js.map",
+                        "type": "source_map",
+                        "headers": {"debug-id": str(debug_id)},
+                    },
+                },
+            }))
+            zf.writestr("~/app.js.map", sourcemap)
+
+        bundle_data = bundle.getvalue()
+        checksum = hashlib.sha1(bundle_data, usedforsecurity=False).hexdigest()
+        upload = BytesIO(gzip.compress(bundle_data))
+        upload.name = checksum
+
+        response = self.client.post(
+            "/api/0/organizations/anyorg/chunk-upload/",
+            data={"file_gzip": upload},
+            headers={"Authorization": f"Bearer {auth_token.token}"},
+        )
+        self.assertEqual(200, response.status_code)
+
+        response = self.client.post(
+            "/api/0/organizations/anyorg/artifactbundle/assemble/",
+            json.dumps({"checksum": checksum, "chunks": [checksum], "projects": [other_project.slug]}),
+            content_type="application/json",
+            headers={"Authorization": f"Bearer {auth_token.token}"},
+        )
+        self.assertEqual(200, response.status_code)
+
+        class FakeMapping:
+            source = "other-project-source.ts"
+            original_line = 0
+            name = "mappedFunction"
+
+        class GoodSourceMap:
+            def lookup_left(self, line, column):
+                if (line, column) == (5, 12):
+                    return FakeMapping()
+
+        mock_ecma426_loads.return_value = GoodSourceMap()
+
+        event_data = {
+            "event_id": uuid.uuid4().hex,
+            "timestamp": datetime.now(timezone.utc).isoformat(),
+            "platform": "javascript",
+            "exception": {
+                "values": [{
+                    "type": "Error",
+                    "value": "test",
+                    "stacktrace": {"frames": [{"filename": "good.js", "lineno": 6, "colno": 12, "in_app": True}]},
+                }]
+            },
+            "debug_meta": {
+                "images": [{"type": "sourcemap", "code_file": "good.js", "debug_id": str(debug_id)}]
+            },
+        }
+
+        # Positive case: the sourcemap works for the project it was uploaded to.
+        other_event = create_event(other_project, other_issue, event_data=event_data, project_digest_order=1)
+        response = self.client.get(f"/issues/issue/{other_issue.id}/event/{other_event.id}/")
+        self.assertEqual(200, response.status_code)
+        self.assertContains(response, "other-project-source.ts")
+        self.assertContains(response, "mappedFunction</span> line <span class=\"font-bold\">1</span>")
+
+        # Negative case: the same debug ID does not resolve across project boundaries.
+        event = create_event(self.project, self.issue, event_data=event_data, project_digest_order=2)
+
+        response = self.client.get(f"/issues/issue/{self.issue.id}/event/{event.id}/")
+        self.assertEqual(200, response.status_code)
+        self.assertContains(response, f"No sourcemaps found for Debug ID {debug_id}")
+        self.assertNotContains(response, "other project source")
+
 
 @tag("samples")
 @tag("integration")

@@ -482,7 +482,7 @@ def issue_event_stacktrace(request, issue, event_pk=None, digest_order=None, nav
         sentry_sdk.capture_exception(e)
 
     try:
-        apply_sourcemaps(parsed_data)
+        apply_sourcemaps(parsed_data, issue.project)
     except Exception as e:
         if settings.DEBUG or settings.I_AM_RUNNING == "TEST":
             # when developing/testing, I _do_ want to get notified
@@ -683,7 +683,7 @@ def issue_event_details(request, issue, event_pk=None, digest_order=None, nav=No
     contexts = get_contexts_enriched_with_ua(parsed_data)
 
     try:
-        sourcemaps_images = get_sourcemap_images(parsed_data)
+        sourcemaps_images = get_sourcemap_images(parsed_data, issue.project)
     except Exception as e:
         if settings.DEBUG or settings.I_AM_RUNNING == "TEST":
             # when developing/testing, I _do_ want to get notified

@@ -420,6 +420,19 @@ def test_issue_list_view(self):
         response = self.client.get(f"/issues/{self.project.id}/")
         self.assertContains(response, self.issue.title())
 
+    def test_issue_list_bulk_action_ignores_issues_from_other_projects(self):
+        other_project = Project.objects.create(name="other")
+        other_issue, _ = get_or_create_issue(other_project)
+
+        response = self.client.post(
+            f"/issues/{self.project.id}/",
+            {"issue_ids[]": [str(other_issue.id)], "action": "resolve"},
+        )
+
+        self.assertEqual(response.status_code, 200)
+        other_issue.refresh_from_db()
+        self.assertFalse(other_issue.is_resolved)
+
     def test_issue_stacktrace(self):
         response = self.client.get(f"/issues/issue/{self.issue.id}/event/{self.event.id}/")
         self.assertContains(response, self.issue.title())

@@ -291,7 +291,7 @@ def issue_list(request, project_pk, state_filter="open"):
 def _issue_list_pt_1(request, project, state_filter="open"):
     if request.method == "POST":
         issue_ids = request.POST.getlist('issue_ids[]')
-        issue_qs = Issue.objects.filter(pk__in=issue_ids)
+        issue_qs = Issue.objects.filter(project=project, is_deleted=False, pk__in=issue_ids)
         illegal_conditions = _q_for_invalid_for_action(request.POST["action"])
         # list() is necessary because we need to evaluate the qs before any actions are actually applied (if we don't,
         # actions are always marked as illegal, because they are applied first, then checked (and applying twice is