fix(canvas): register system.canvases and retire the home-canvas concept

posthog/hogql/database/schema/system.py

@@ -2188,6 +2188,61 @@ def ticket_assignment_join(join_to_add: LazyJoinToAdd, context: HogQLContext, no
 )
 
 
+canvases: PostgresTable = PostgresTable(
+    name="canvases",
+    postgres_table_name="posthog_canvas",
+    access_scope="canvas",
+    # Mirror the REST API's default filter: soft-deleted canvases are not exposed.
+    predicates=[parse_expr("deleted != true")],
+    description="Canvases (agent-built sandboxed browser apps, filed into channels); one row per canvas (soft-deleted canvases are excluded).",
+    fields={
+        "id": StringDatabaseField(name="id", description="Canvas UUID."),
+        "team_id": IntegerDatabaseField(name="team_id"),
+        "channel_id": StringDatabaseField(
+            name="channel_id", description="Channel the canvas is filed into (tasks Channel UUID)."
+        ),
+        "name": StringDatabaseField(name="name", description="Canvas name."),
+        "template_id": StringDatabaseField(
+            name="template_id", description="Template the canvas was created from, e.g. 'freeform'."
+        ),
+        "context": StringDatabaseField(
+            name="context", description="Author-written context (markdown) passed to generation tasks."
+        ),
+        "generation_task_id": StringDatabaseField(
+            name="generation_task_id",
+            nullable=True,
+            description="Task currently generating this canvas; joins to tasks.id.",
+        ),
+        "pinned_at": DateTimeDatabaseField(
+            name="pinned_at",
+            nullable=True,
+            description="When the canvas was pinned to its channel; NULL if not pinned.",
+        ),
+        "current_source_version_id": StringDatabaseField(
+            name="current_source_version_id",
+            nullable=True,
+            description="The canvas's head source version; NULL until the first publish.",
+        ),
+        "published_build_id": StringDatabaseField(
+            name="published_build_id",
+            nullable=True,
+            description="Build whose artifact the canvas app currently renders; NULL until the first successful build.",
+        ),
+        "created_by_id": IntegerDatabaseField(
+            name="created_by_id", nullable=True, description="User who created the canvas."
+        ),
+        "_deleted": BooleanDatabaseField(name="deleted", hidden=True),
+        "deleted": ExpressionField(
+            name="deleted",
+            expr=ast.Call(name="toInt", args=[ast.Field(chain=["_deleted"])]),
+            description="1 if the canvas has been deleted, 0 otherwise (always 0 here due to the table filter).",
+        ),
+        "created_at": DateTimeDatabaseField(name="created_at", description="When the canvas was created."),
+        "updated_at": DateTimeDatabaseField(name="updated_at", description="When the canvas was last updated."),
+    },
+)
+
+
 tags: PostgresTable = PostgresTable(
     name="tags",
     postgres_table_name="posthog_tag",
@@ -2229,6 +2284,7 @@ class SystemTables(TableNode):
             name="business_knowledge_documents", table=business_knowledge_documents
         ),
         "business_knowledge_sources": TableNode(name="business_knowledge_sources", table=business_knowledge_sources),
+        "canvases": TableNode(name="canvases", table=canvases),
         "cohort_calculation_history": TableNode(name="cohort_calculation_history", table=cohort_calculation_history),
         "cohorts": TableNode(name="cohorts", table=cohorts),
         "custom_property_definitions": TableNode(name="custom_property_definitions", table=custom_property_definitions),

posthog/hogql/database/schema/test/test_system_tables.py

@@ -581,6 +581,15 @@ def _create_task(team: Team, label: str):
     )
 
 
+def _create_canvas(team: Team, label: str):
+    Channel = apps.get_model("tasks", "Channel")
+    Canvas = apps.get_model("canvas", "Canvas")
+
+    with team_scope(team.pk):
+        channel = Channel.objects.create(team=team, name=f"channel_for_canvas_{label}")
+        return Canvas.objects.create(team=team, channel=channel, name=f"canvas_{label}")
+
+
 def _create_task_run(team: Team, label: str):
     Task = apps.get_model("tasks", "Task")
     TaskRun = apps.get_model("tasks", "TaskRun")
@@ -681,6 +690,7 @@ def _create_business_knowledge_chunk(team: Team, label: str):
     ("business_knowledge_chunks", _create_business_knowledge_chunk),
     ("business_knowledge_documents", _create_business_knowledge_document),
     ("business_knowledge_sources", _create_business_knowledge_source),
+    ("canvases", _create_canvas),
     ("cohorts", _create_cohort),
     ("cohort_calculation_history", _create_cohort_calculation_history),
     ("custom_property_definitions", _create_custom_property_definition),
@@ -820,6 +830,39 @@ def test_internal_environments_excluded(self):
         assert str(internal_env.pk) not in ids
 
 
+class TestSystemTablesCanvasDeletedExclusion(BaseTest):
+    """Verify the canvases system table excludes soft-deleted canvases,
+    mirroring the REST API's default filter."""
+
+    def test_generated_sql_includes_deleted_predicate(self):
+        db = Database.create_for(team=self.team, user=self.user)
+        context = HogQLContext(team_id=self.team.pk, enable_select_queries=True, database=db)
+        query, _ = prepare_and_print_ast(parse_select("SELECT id FROM system.canvases"), context, dialect="clickhouse")
+        assert "system__canvases.deleted" in query
+        assert f"equals(system__canvases.team_id, {self.team.pk})" in query
+
+
+class TestSystemTablesCanvasDeletedExclusionIsolation(NonAtomicBaseTest):
+    """End-to-end check that soft-deleted canvases are never returned via HogQL."""
+
+    CLASS_DATA_LEVEL_SETUP = False
+
+    def test_deleted_canvases_excluded(self):
+        Channel = apps.get_model("tasks", "Channel")
+        Canvas = apps.get_model("canvas", "Canvas")
+
+        with team_scope(self.team.pk):
+            channel = Channel.objects.create(team=self.team, name="canvas-exclusion-channel")
+            live_canvas = Canvas.objects.create(team=self.team, channel=channel, name="live")
+            deleted_canvas = Canvas.objects.create(team=self.team, channel=channel, name="deleted", deleted=True)
+
+        response = execute_hogql_query("SELECT id FROM system.canvases", team=self.team, user=self.user)
+        ids = {str(row[0]) for row in response.results}
+
+        assert str(live_canvas.pk) in ids
+        assert str(deleted_canvas.pk) not in ids
+
+
 class TestSystemTablesTaskInternalExclusion(BaseTest):
     """Verify the tasks system table excludes internal tasks (signals pipeline, etc.)
     mirroring the REST API's default filter."""