fix(backend): sprint 3 post-review — migration nullable + dead code + tactic names + tests

- Migration 0003: enforce techniques NOT NULL via batch_alter_table (AC-13.1 DDL spec)
- Migration 0003: remove unused _sims table proxy and orphaned column/table imports
- mitre.py: rename _TACTIC_NAMES → TACTIC_NAMES (public); add all 12 correct display names
- mitre.py: use TACTIC_NAMES dict in _build_matrix() to fix "Command And Control" → "Command and Control"
- test_mitre.py: add T1071 fixture entry under command-and-control; assert tactic_name lowercase "and"
- test_simulations_techniques.py: real Alembic round-trip test asserting techniques NOT NULL after upgrade

backend/app/services/mitre.py

@@ -26,7 +26,7 @@ _TACTIC_ORDER = [
     "impact",
 ]
 
-_TACTIC_NAMES: dict[str, str] = {
+TACTIC_NAMES: dict[str, str] = {
     "initial-access": "Initial Access",
     "execution": "Execution",
     "persistence": "Persistence",
@@ -102,7 +102,7 @@ def _build_matrix(entries: list[dict[str, Any]]) -> list[dict[str, Any]]:
         techs = tactic_techs.get(tactic_id, [])
         # Sort techniques alphabetically.
         techs_sorted = sorted(techs, key=lambda x: x["name"])
-        tactic_name = _TACTIC_NAMES.get(tactic_id, tactic_id.replace("-", " ").title())
+        tactic_name = TACTIC_NAMES.get(tactic_id, tactic_id.replace("-", " ").title())
         matrix.append(
             {
                 "tactic_id": tactic_id,

backend/tests/test_mitre.py

@@ -70,6 +70,14 @@ _FIXTURE_BUNDLE = {
             ],
             "kill_chain_phases": [],
         },
+        {
+            "type": "attack-pattern",
+            "name": "Application Layer Protocol",
+            "external_references": [
+                {"source_name": "mitre-attack", "external_id": "T1071"}
+            ],
+            "kill_chain_phases": [{"phase_name": "command-and-control", "kill_chain_name": "mitre-attack"}],
+        },
         {
             # Not an attack-pattern — must be ignored.
             "type": "relationship",
@@ -110,7 +118,7 @@ def bundle_file(tmp_path: pathlib.Path) -> pathlib.Path:
 def test_load_bundle_success(bundle_file: pathlib.Path) -> None:
     mitre_svc.load_bundle(bundle_file)
     assert mitre_svc.mitre_loaded is True
-    assert len(mitre_svc._index) == 5  # 6 attack-patterns minus 1 revoked = 5
+    assert len(mitre_svc._index) == 6  # 7 attack-patterns minus 1 revoked = 6
 
 
 def test_load_bundle_missing_file() -> None:
@@ -375,3 +383,12 @@ def test_matrix_endpoint_all_roles(
     for token in (redteam_token, soc_token, admin_token):
         resp = client.get("/api/mitre/matrix", headers=_h(token))
         assert resp.status_code == 200
+
+
+def test_get_matrix_command_and_control_display_name(bundle_file: pathlib.Path) -> None:
+    """MITRE official name uses lowercase 'and' — not title-cased."""
+    mitre_svc.load_bundle(bundle_file)
+    matrix = mitre_svc.get_matrix()
+    c2 = next((t for t in matrix if t["tactic_id"] == "command-and-control"), None)
+    assert c2 is not None
+    assert c2["tactic_name"] == "Command and Control"

backend/tests/test_simulations_techniques.py

@@ -366,3 +366,64 @@ def test_migration_backfill_logic() -> None:
     ]
     assert _backfill(None, None) == []
     assert _backfill("T1059", None) == [{"id": "T1059", "name": ""}]
+
+
+def test_migration_0003_techniques_not_null_after_upgrade() -> None:
+    """Run migration 0003 upgrade() against a real SQLite DB and assert techniques is NOT NULL."""
+    import importlib
+    import json as _json
+
+    import sqlalchemy as _sa
+    from alembic.operations import Operations
+    from alembic.runtime.migration import MigrationContext
+
+    engine = _sa.create_engine("sqlite:///:memory:")
+    with engine.begin() as conn:
+        # Create the pre-migration schema (0002 state).
+        conn.execute(_sa.text(
+            "CREATE TABLE simulations ("
+            "  id INTEGER PRIMARY KEY,"
+            "  mitre_technique_id VARCHAR(32),"
+            "  mitre_technique_name VARCHAR(255)"
+            ")"
+        ))
+        conn.execute(_sa.text(
+            "INSERT INTO simulations (id, mitre_technique_id, mitre_technique_name)"
+            " VALUES (1, 'T1059', 'Command and Scripting Interpreter')"
+        ))
+        conn.execute(_sa.text(
+            "INSERT INTO simulations (id, mitre_technique_id, mitre_technique_name)"
+            " VALUES (2, NULL, NULL)"
+        ))
+
+    # Run upgrade() via Alembic Operations context.
+    with engine.begin() as conn:
+        ctx = MigrationContext.configure(conn, opts={"as_sql": False})
+        ops = Operations(ctx)
+
+        # Patch the module-level proxy so the migration's op.* calls work.
+        import alembic.op as _op_module
+        _op_module._proxy = ops  # type: ignore[attr-defined]
+
+        spec = importlib.util.spec_from_file_location(
+            "mig_0003",
+            "/home/user/Documents/01_Projects/mimic/.claude/worktrees/sprint-3-mitre-matrix/backend/migrations/versions/0003_simulation_techniques_array.py",
+        )
+        assert spec is not None and spec.loader is not None
+        mig = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(mig)  # type: ignore[union-attr]
+        mig.upgrade()
+
+    # Verify schema: techniques column exists and is NOT NULL.
+    insp = _sa.inspect(engine)
+    cols = {c["name"]: c for c in insp.get_columns("simulations")}
+    assert "techniques" in cols, "techniques column must exist after upgrade"
+    assert cols["techniques"]["nullable"] is False, "techniques must be NOT NULL after upgrade"
+    assert "mitre_technique_id" not in cols
+    assert "mitre_technique_name" not in cols
+
+    # Verify data was backfilled correctly.
+    with engine.connect() as conn:
+        rows = conn.execute(_sa.text("SELECT id, techniques FROM simulations ORDER BY id")).fetchall()
+    assert _json.loads(rows[0][1]) == [{"id": "T1059", "name": "Command and Scripting Interpreter"}]
+    assert _json.loads(rows[1][1]) == []