diff --git a/CHANGELOG.yaml b/CHANGELOG.yaml
index 1ff055c1..c8047117 100644
--- a/CHANGELOG.yaml
+++ b/CHANGELOG.yaml
@@ -16,6 +16,7 @@
   fixes:
   - "OpenRouter Client: A failed model/provider list fetch at startup no longer sticks until the server is restarted — later config saves and client status refreshes now retry it. Setting the API key for the first time during initial setup also correctly triggers the provider fetch."
   - "Generation Error Dialog: When several generations failed at the same time (e.g. an API throttle hitting both a summarization and a background task), only the most recent error could be answered — the earlier generation was never resumed and its result (such as a scene summary) was silently lost. Error dialogs are now queued and answered one after another, and pending dialogs are cancelled cleanly when the scene is unloaded or the frontend disconnects."
+  - "Timeline Rollback: Previewing a revision could fail with an 'unhashable type' error when the scene's changelog contained deltas that diverged from the base snapshot — reconstruction now repairs the affected message history (and other list data) instead of crashing the timeline."
 
 0.38.0:
   features:
diff --git a/src/talemate/changelog.py b/src/talemate/changelog.py
index c0fc77e0..7525e294 100644
--- a/src/talemate/changelog.py
+++ b/src/talemate/changelog.py
@@ -119,6 +119,18 @@ EXCLUDE_FROM_DELTAS_REGEX = [
     # re.compile(r"root\['some_array'\]\[\d+\]\['volatile_field'\]"),
 ]
 
+# Scene-data fields that must always be lists. Delta application with
+# force=True can leave an int-keyed dict in their place when an iterable op
+# targets a path whose parent is missing (baseline divergence) — deepdiff
+# creates ``{index: item}`` instead of a list.
+_LIST_FIELDS = (
+    "history",
+    "archived_history",
+    "layered_history",
+    "active_characters",
+    "game_state_watch_paths",
+)
+
 
 # Helper minimal scene reference compatible with this module's helpers
 class _SceneRef:
@@ -685,6 +697,61 @@ def _get_overall_latest_revision(scene: "Scene") -> int:
     return latest_rev
 
 
+def _coerce_forced_list(value) -> tuple[list | None, bool]:
+    """Convert a force-mode artifact — an int-keyed dict where a list is
+    expected — back into a list ordered by index.
+
+    Returns ``(converted_list, True)`` when the value was such an artifact,
+    ``(None, False)`` otherwise. Dicts with any non-index key are left alone.
+    """
+    if not isinstance(value, dict):
+        return None, False
+
+    indexed: list[tuple[int, object]] = []
+    for key, item in value.items():
+        if isinstance(key, bool):
+            return None, False
+        if isinstance(key, int):
+            indexed.append((key, item))
+        elif isinstance(key, str) and re.fullmatch(r"-?\d+", key):
+            # int keys become strings when the data round-trips through JSON
+            indexed.append((int(key), item))
+        else:
+            return None, False
+
+    indexed.sort(key=lambda pair: pair[0])
+    return [item for _, item in indexed], True
+
+
+def _repair_forced_list_fields(data: dict) -> int:
+    """Restore list fields that force-mode delta application turned into
+    int-keyed dicts (see ``_LIST_FIELDS``), including the nested layers of
+    ``layered_history``.
+
+    Returns the number of fields repaired.
+    """
+    repaired: list[str] = []
+
+    for field in _LIST_FIELDS:
+        converted, was_forced = _coerce_forced_list(data.get(field))
+        if was_forced:
+            data[field] = converted
+            repaired.append(field)
+
+    layered = data.get("layered_history")
+    if isinstance(layered, list):
+        for i, layer in enumerate(layered):
+            converted, was_forced = _coerce_forced_list(layer)
+            if was_forced:
+                layered[i] = converted
+                repaired.append(f"layered_history[{i}]")
+
+    if repaired:
+        log.warning("repaired_forced_list_fields", fields=repaired)
+
+    return len(repaired)
+
+
 def _repair_history(data: dict) -> int:
     """Backfill required SceneMessage fields on bare-fragment history entries.
 
@@ -729,6 +796,7 @@ async def reconstruct_cleanup(data: dict) -> dict:
         )
         data["shared_context"] = ""
 
+    _repair_forced_list_fields(data)
     _repair_history(data)
     return data
 
diff --git a/tests/test_changelog.py b/tests/test_changelog.py
index 8d2ffda6..9d973071 100644
--- a/tests/test_changelog.py
+++ b/tests/test_changelog.py
@@ -1294,6 +1294,132 @@ async def test_reconstruct_cleanup_repairs_bare_history_entries():
     assert repaired["asset_type"] == "scene_illustration"
 
 
+@pytest.mark.asyncio
+async def test_reconstruct_cleanup_repairs_forced_dict_history():
+    """An int-keyed dict where history should be a list (Delta force=True
+    artifact) is converted back to a list ordered by index — issue #81."""
+    data = {
+        "history": {
+            2: {"message": "third", "typ": "narrator", "source": "ai", "flags": 0},
+            1: {"message": "second", "typ": "narrator", "source": "ai", "flags": 0},
+        }
+    }
+
+    result = await reconstruct_cleanup(data)
+
+    history = result["history"]
+    assert isinstance(history, list)
+    assert [entry["message"] for entry in history] == ["second", "third"]
+    # the preview handler slices this — must not raise
+    assert history[-20:] == history
+
+
+@pytest.mark.asyncio
+async def test_reconstruct_cleanup_repairs_forced_dict_history_string_keys():
+    """Index keys arrive as strings when the corrupted data round-tripped
+    through JSON — those convert too, and bare entries still get repaired."""
+    data = {"history": {"1": {"asset_id": "abc123"}, "0": {"m": 0}}}
+
+    result = await reconstruct_cleanup(data)
+
+    history = result["history"]
+    assert isinstance(history, list)
+    assert len(history) == 2
+    assert history[1]["asset_id"] == "abc123"
+    # _repair_history runs after the coercion and backfills required fields
+    for entry in history:
+        assert entry["typ"] == "narrator"
+        assert "message" in entry
+
+
+@pytest.mark.asyncio
+async def test_reconstruct_cleanup_repairs_all_forced_list_fields():
+    """Every list field is normalized, including nested layered_history layers."""
+    data = {
+        "history": {0: {"message": "a", "typ": "narrator"}},
+        "archived_history": {0: {"text": "summary"}},
+        "layered_history": {0: [{"text": "layer0"}], 1: {0: {"text": "layer1"}}},
+        "active_characters": {0: "Alice", 1: "Bob"},
+        "game_state_watch_paths": {0: "game.state.foo"},
+    }
+
+    result = await reconstruct_cleanup(data)
+
+    assert isinstance(result["history"], list)
+    assert result["archived_history"] == [{"text": "summary"}]
+    assert result["layered_history"] == [[{"text": "layer0"}], [{"text": "layer1"}]]
+    assert result["active_characters"] == ["Alice", "Bob"]
+    assert result["game_state_watch_paths"] == ["game.state.foo"]
+
+
+@pytest.mark.asyncio
+async def test_reconstruct_cleanup_leaves_legit_dicts_and_lists_alone():
+    """Dicts with non-index keys and healthy lists pass through untouched."""
+    data = {
+        "history": [{"message": "a", "typ": "narrator", "source": "ai", "flags": 0}],
+        # malformed digit-ish key — must not be treated as an index (and must
+        # not raise from int())
+        "archived_history": {"--5": {"text": "x"}},
+        "character_data": {"Alice": {"name": "Alice"}},
+        "agent_state": {"0_custom": True, "narrator": {}},
+    }
+
+    result = await reconstruct_cleanup(data)
+
+    assert result["history"] == data["history"]
+    assert result["archived_history"] == {"--5": {"text": "x"}}
+    assert result["character_data"] == {"Alice": {"name": "Alice"}}
+    assert result["agent_state"] == {"0_custom": True, "narrator": {}}
+
+
+@pytest.mark.asyncio
+async def test_reconstruct_scene_data_repairs_forced_dict_history(mock_scene):
+    """End-to-end issue #81 repro: an iterable_item_added delta targeting a
+    missing history parent makes Delta(force=True) build history as an
+    int-keyed dict — reconstruction must still return a sliceable list."""
+    base_data = {"characters": [], "entries": []}  # no history at all
+    base_path = _base_path(mock_scene)
+    os.makedirs(os.path.dirname(base_path), exist_ok=True)
+    with open(base_path, "w") as f:
+        json.dump(base_data, f)
+
+    log_data = {
+        "version": 1,
+        "base": f"{mock_scene.filename}.base.json",
+        "start_rev": 0,
+        "deltas": [
+            {
+                "rev": 1,
+                "ts": 1672531200,
+                "delta": {
+                    "iterable_item_added": {
+                        "root['history'][1]": {
+                            "message": "hello",
+                            "typ": "narrator",
+                            "source": "ai",
+                            "flags": 0,
+                        }
+                    }
+                },
+                "meta": {},
+            }
+        ],
+        "latest_rev": 1,
+    }
+    log_path = _changelog_log_path(mock_scene, 0)
+    with open(log_path, "w") as f:
+        json.dump(log_data, f)
+
+    result = await reconstruct_scene_data(mock_scene, to_rev=1)
+
+    history = result["history"]
+    assert isinstance(history, list)
+    assert len(history) == 1
+    assert history[0]["message"] == "hello"
+    # the timeline preview slice that crashed in issue #81
+    assert history[-20:] == history
+
+
 @pytest.mark.asyncio
 async def test_reconstruct_scene_data_repairs_force_true_corruption(mock_scene):
     """End-to-end: orphan dict-add on a non-existent history index reconstructs to a loadable entry."""