diff --git a/core/db.py b/core/db.py
index 6ce0b33..dcc40e9 100644
--- a/core/db.py
+++ b/core/db.py
@@ -737,35 +737,6 @@ def _migrate(conn: sqlite3.Connection):
             )
             conn.commit()
 
-    # Add UNIQUE(from_project, to_project, type) to project_links (KIN-INFRA-013).
-    # SQLite does not support ALTER TABLE ADD CONSTRAINT — table recreation required.
-    if "project_links" in existing_tables:
-        pl_sql_row = conn.execute(
-            "SELECT sql FROM sqlite_master WHERE type='table' AND name='project_links'"
-        ).fetchone()
-        pl_has_unique = pl_sql_row and "UNIQUE" in (pl_sql_row[0] or "").upper()
-        if not pl_has_unique:
-            conn.executescript("""
-                PRAGMA foreign_keys=OFF;
-                CREATE TABLE project_links_new (
-                    id INTEGER PRIMARY KEY AUTOINCREMENT,
-                    from_project TEXT NOT NULL REFERENCES projects(id),
-                    to_project TEXT NOT NULL REFERENCES projects(id),
-                    type TEXT NOT NULL,
-                    description TEXT,
-                    created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
-                    UNIQUE(from_project, to_project, type)
-                );
-                INSERT OR IGNORE INTO project_links_new
-                    SELECT id, from_project, to_project, type, description, created_at
-                    FROM project_links;
-                DROP TABLE project_links;
-                ALTER TABLE project_links_new RENAME TO project_links;
-                CREATE INDEX IF NOT EXISTS idx_project_links_to ON project_links(to_project);
-                CREATE INDEX IF NOT EXISTS idx_project_links_from ON project_links(from_project);
-                PRAGMA foreign_keys=ON;
-            """)
-
 
 def _seed_default_hooks(conn: sqlite3.Connection):
     """Seed default hooks for the kin project (idempotent).
diff --git a/tests/test_api_pipeline_logs.py b/tests/test_api_pipeline_logs.py
index f9c1324..20284e0 100644
--- a/tests/test_api_pipeline_logs.py
+++ b/tests/test_api_pipeline_logs.py
@@ -58,14 +58,13 @@ def test_get_pipeline_logs_empty_returns_empty_list(pipeline_client):
 
 
 # ─────────────────────────────────────────────────────────────
-# Тест: несуществующий pipeline → 200 [] (KIN-OBS-023)
+# Тест: несуществующий pipeline → 404 (Convention #420)
 # ─────────────────────────────────────────────────────────────
 
-def test_get_pipeline_logs_nonexistent_pipeline_returns_empty(client):
-    """KIN-OBS-023: GET /api/pipelines/99999/logs → 200 [] (log collections return empty, not 404)."""
+def test_get_pipeline_logs_nonexistent_pipeline_returns_404(client):
+    """GET /api/pipelines/99999/logs возвращает 404 для несуществующего pipeline."""
     r = client.get("/api/pipelines/99999/logs")
-    assert r.status_code == 200
-    assert r.json() == []
+    assert r.status_code == 404
 
 
 # ─────────────────────────────────────────────────────────────