feat: retain pending publications (#97)

src/fenris/store.py

@@ -12,7 +12,7 @@ from typing import Optional
 
 
 # Schema version - increment on each migration
-SCHEMA_VERSION = 3
+SCHEMA_VERSION = 4
 
 
 # Packaged default placement (spec §8.3). The config may override it, but a
@@ -221,6 +221,19 @@ def _create_schema(conn: sqlite3.Connection):
         )
     """)
 
+    _create_pending_publications(conn)
+
+
+def _create_pending_publications(conn: sqlite3.Connection) -> None:
+    """Create private staging for valid observations awaiting derivation."""
+    conn.execute("""
+        CREATE TABLE IF NOT EXISTS pending_publications (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            sample_ts TEXT NOT NULL,
+            payload TEXT NOT NULL
+        )
+    """)
+
 
 def _apply_migrations(conn: sqlite3.Connection, current_version: int):
     """Apply forward-only migrations from current_version to SCHEMA_VERSION.
@@ -275,6 +288,12 @@ def _apply_migrations(conn: sqlite3.Connection, current_version: int):
             """)
         current_version = 3
 
+    # Migration 3→4: retain acquired observations until derived evidence can
+    # be published atomically (issue #97, ADR 0011).
+    if current_version < 4:
+        _create_pending_publications(conn)
+        current_version = 4
+
 
 def migrate_to_latest(store_path: Path) -> int:
     """Apply forward-only migrations to bring the store to SCHEMA_VERSION.