fix: preserve YAML project cards regardless of key order

python/lean_pool/rebase.py

@@ -29,13 +29,14 @@
 import sys
 from pathlib import Path
 
+import yaml
+
 from lean_pool.exposition.source_text import code_view
 
 logger = logging.getLogger(__name__)
 
 REGISTRY = "LeanPool/projects.yml"
 INDEX = "LeanPool.lean"
-CARD_PREFIX = "  - slug: "
 # The only conflicts this module claims to resolve.
 RESOLVABLE = frozenset({INDEX, REGISTRY})
 
@@ -78,22 +79,61 @@ def render_index(root: Path) -> str:
     )
 
 
+def _project_nodes(text: str) -> yaml.SequenceNode:
+    """Read card boundaries from YAML rather than assuming a first key."""
+    root = yaml.compose(text, Loader=yaml.SafeLoader)
+    if not isinstance(root, yaml.MappingNode) or len(root.value) != 1:
+        raise ValueError("Expected a registry containing only projects")
+    key, projects = root.value[0]
+    if key.value != "projects" or not isinstance(projects, yaml.SequenceNode):
+        raise ValueError("Expected projects to be a sequence")
+    if projects.flow_style and projects.value:
+        raise ValueError("Project cards must use a block sequence")
+    if any(not isinstance(card, yaml.MappingNode) for card in projects.value):
+        raise ValueError("Each project card must be a mapping")
+    return projects
+
+
+def _card_slug(card: yaml.MappingNode) -> str:
+    """Require one unambiguous string slug, in any mapping position."""
+    slugs = [value for key, value in card.value if key.value == "slug"]
+    if (
+        len(slugs) != 1
+        or not isinstance(slugs[0], yaml.ScalarNode)
+        or slugs[0].tag != "tag:yaml.org,2002:str"
+        or not slugs[0].value.strip()
+    ):
+        raise ValueError("Each project card must have exactly one nonempty string slug")
+    return slugs[0].value
+
+
 def split_cards(text: str) -> tuple[str, list[tuple[str, str]]]:
     """Split a registry into its header and its cards, as verbatim text.
 
     Returns ``(header, [(slug, block)])`` where concatenating the header and
     every block reproduces ``text`` exactly.
     """
-    lines = text.splitlines(keepends=True)
-    starts = [i for i, line in enumerate(lines) if line.startswith(CARD_PREFIX)]
+    projects = _project_nodes(text)
+    nodes = projects.value
+    entries = [
+        token
+        for token in yaml.scan(text, Loader=yaml.SafeLoader)
+        if isinstance(token, yaml.tokens.BlockEntryToken)
+        and token.start_mark.column == projects.start_mark.column
+    ]
+    starts = [text.rfind("\n", 0, token.start_mark.index) + 1 for token in entries]
+    if len(starts) != len(nodes):
+        raise ValueError("Expected one sequence item per project card")
     if not starts:
         return text, []
-    header = "".join(lines[: starts[0]])
+    header = text[: starts[0]]
     cards: list[tuple[str, str]] = []
-    for index, start in enumerate(starts):
-        end = starts[index + 1] if index + 1 < len(starts) else len(lines)
-        slug = lines[start][len(CARD_PREFIX) :].strip()
-        cards.append((slug, "".join(lines[start:end])))
+    for index, (start, node) in enumerate(zip(starts, nodes, strict=True)):
+        end = starts[index + 1] if index + 1 < len(starts) else len(text)
+        slug = _card_slug(node)
+        if any(existing == slug for existing, _ in cards):
+            raise ValueError(f"Duplicate project slug: {slug}")
+        cards.append((slug, text[start:end]))
     return header, cards
 
 
@@ -122,7 +162,10 @@ def merge_registry(base: str, ours: str, theirs: str) -> str:
     # run into the first appended card.
     if merged and not merged.endswith("\n"):
         merged += "\n"
-    return merged + "".join(block for _, block in added)
+    result = merged + "".join(block for _, block in added)
+    # Reject incompatible layouts instead of pushing a malformed registry.
+    split_cards(result)
+    return result
 
 
 def resolvable(conflicts: list[str]) -> bool:

python/tests/test_rebase.py

@@ -5,6 +5,7 @@
 from pathlib import Path
 
 import pytest
+import yaml
 
 from lean_pool.rebase import (
     main,
@@ -155,6 +156,83 @@ def test_split_cards_round_trips() -> None:
     assert header + "".join(block for _, block in cards) == OURS
 
 
+@pytest.mark.parametrize("indent", ["", "  ", "    "])
+def test_split_cards_uses_yaml_boundaries_and_decoded_slugs(indent: str) -> None:
+    """Key order, quoting, comments and nested lists do not change card identity."""
+    text = (
+        "# Keep this header\nprojects:\n"
+        f'{indent}- title: "First: project"\n'
+        f"{indent}  summary: |\n{indent}    - slug: not-a-card\n"
+        f"{indent}  tags:\n{indent}    - slug: nested\n"
+        f"{indent}  slug: 'alpha' # Keep this comment\n"
+        f'{indent}- slug: "beta"\n{indent}  title: Beta\n'
+    )
+    header, cards = split_cards(text)
+    assert [slug for slug, _ in cards] == ["alpha", "beta"]
+    assert header + "".join(block for _, block in cards) == text
+
+
+def test_merge_preserves_title_first_added_cards_verbatim() -> None:
+    """Regression: the automatic updater must not silently drop a title-first card."""
+    added = "  - title: Delta\n    slug: 'delta' # quoted identity\n"
+    merged = merge_registry(BASE, OURS, BASE + added)
+    assert merged == OURS + added
+    assert [card["slug"] for card in yaml.safe_load(merged)["projects"]] == [
+        "alpha",
+        "beta",
+        "gamma",
+        "delta",
+    ]
+
+
+def test_merge_preserves_cards_with_keys_below_the_dash() -> None:
+    """A standalone YAML sequence marker is a valid card boundary too."""
+    added = "  - # project comment\n    title: Delta\n    slug: delta\n"
+    merged = merge_registry(BASE, OURS, BASE + added)
+    assert merged == OURS + added
+    assert yaml.safe_load(merged)["projects"][-1]["slug"] == "delta"
+
+
+def test_merge_recognizes_title_first_base_and_main_cards() -> None:
+    """Reordered keys and quoted slugs must not duplicate existing cards."""
+    base = "projects:\n  - title: Alpha\n    slug: 'alpha'\n"
+    ours = base + '  - title: Delta\n    slug: "delta"\n'
+    theirs = "projects:\n  - slug: alpha\n    title: Alpha\n"
+    theirs += "  - slug: delta\n    title: Delta\n"
+    assert merge_registry(base, ours, theirs) == ours
+
+
+@pytest.mark.parametrize(
+    "text",
+    [
+        "projects:\n  - title: Missing slug\n",
+        "projects:\n  - slug: alpha\n    slug: beta\n",
+        "projects:\n  - slug: alpha\n  - slug: 'alpha'\n",
+        "projects:\n  - slug: 123\n",
+        "projects:\n  - slug: ''\n",
+        "projects: [{slug: alpha}, {slug: beta}]\n",
+        "projects:\n  - &card {slug: alpha}\n  - *card\n",
+        "projects:\n  - not-a-mapping\n",
+        "projects: {}\n",
+    ],
+)
+def test_split_cards_rejects_ambiguous_registries(text: str) -> None:
+    """Malformed identities and unsupported layouts fail before anything is pushed."""
+    with pytest.raises(ValueError):
+        split_cards(text)
+
+
+def test_split_cards_covers_every_real_project() -> None:
+    """Every YAML project, including title-first entries, gets a verbatim block."""
+    root = Path(__file__).resolve().parents[2]
+    text = (root / "LeanPool/projects.yml").read_text(encoding="utf-8")
+    header, cards = split_cards(text)
+    assert [slug for slug, _ in cards] == [
+        card["slug"] for card in yaml.safe_load(text)["projects"]
+    ]
+    assert header + "".join(block for _, block in cards) == text
+
+
 def test_merge_keeps_both_additions() -> None:
     """The merged registry has the card main added and the card we added."""
     merged = merge_registry(BASE, OURS, THEIRS)