From f95bea6dfa0d77fe575ed64b6a42a10ba5652d5d Mon Sep 17 00:00:00 2001
From: Rick Lupton <mail@ricklupton.name>
Date: Wed, 20 Nov 2024 21:56:29 +0000
Subject: [PATCH 1/2] Ignore unknown IDs in sorting CrdtSequence

Unknown IDs shouldn't happen anyway, but they have happened where the
part of the file where they were defined was not being parsed properly.
With this change the behaviour is more robust.
---
 src/rmscene/crdt_sequence.py |  7 ++++++-
 tests/test_crdt_sequence.py  | 11 +++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/rmscene/crdt_sequence.py b/src/rmscene/crdt_sequence.py
index 6207b90..8d32caa 100644
--- a/src/rmscene/crdt_sequence.py
+++ b/src/rmscene/crdt_sequence.py
@@ -2,6 +2,7 @@
 
 """
 
+import logging
 import typing as tp
 from typing import Iterable
 from collections import defaultdict
@@ -9,6 +10,8 @@
 
 from .tagged_block_common import CrdtId
 
+_logger = logging.getLogger(__name__)
+
 
 # If the type constraint is for a CrdtSequenceItem[Superclass], then a
 # CrdtSequenceItem[Subclass] would do, so it is covariant.
@@ -108,7 +111,9 @@ def toposort_items(items: Iterable[CrdtSequenceItem]) -> Iterable[CrdtId]:
 
     def _side_id(item, side):
         side_id = getattr(item, f"{side}_id")
-        if side_id == END_MARKER:
+        if side_id == END_MARKER or side_id not in item_dict:
+            if side_id != END_MARKER:
+                _logger.debug("Ignoring unknown %s_id %s of %s", side, side_id, item)
             return "__start" if side == "left" else "__end"
         else:
             return side_id
diff --git a/tests/test_crdt_sequence.py b/tests/test_crdt_sequence.py
index 79a8db0..2ef32bf 100644
--- a/tests/test_crdt_sequence.py
+++ b/tests/test_crdt_sequence.py
@@ -71,6 +71,17 @@ def test_unknown_id():
     assert result1 == [cid(28), cid(31), cid(33), cid(15)]
 
 
+def test_unknown_id_at_right():
+    items = [
+        make_item(14, 0, 0, 0, "A"),
+        make_item(19, 14, 15, 0, "V"),
+        # item 15 is not defined -- this shouldn't happen, as there should be a
+        # tombstone, but don't want to raise errors in this case
+    ]
+    result = list(CrdtSequence(items))
+    assert result == [cid(14), cid(19)]
+
+
 def test_iterates_in_order():
     # Order should be "AB"
     items = [

From 510788ace841ede7e02977d82c7c760e76c3a563 Mon Sep 17 00:00:00 2001
From: Rick Lupton <mail@ricklupton.name>
Date: Wed, 20 Nov 2024 22:05:16 +0000
Subject: [PATCH 2/2] Update changelog

---
 README.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/README.md b/README.md
index dc2e814..addae66 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,9 @@ To convert rm files to other formats, you can use [rmc](https://github.com/rickl
 
 ### Unreleased
 
+Fixes:
+- Fix AssertionError when some ids are missing in a `CrdtSequence` ([#36](https://github.com/ricklupton/rmscene/pull/36))
+
 ### v0.6.0
 
 New features: