Order PR stack tables by base chain

Author: fjord-oai

src/core/CommitMetadata.order.test.ts

@@ -10,6 +10,24 @@ test("stack_order preserves stack group order", () => {
   expect(ids(actual)).toEqual(["A", "B", "C"]);
 });
 
+test("stack_order derives stack group order from base chain", () => {
+  const commit_range = range(["A", "B", "C"]);
+  commit_range.group_list.reverse();
+
+  const actual = CommitMetadata.stack_order(commit_range);
+
+  expect(ids(actual)).toEqual(["A", "B", "C"]);
+});
+
+test("stack_order does not drop groups with incomplete base links", () => {
+  const commit_range = range(["A", "B", "C"]);
+  commit_range.group_list[1]!.base = "missing";
+
+  const actual = CommitMetadata.stack_order(commit_range);
+
+  expect(ids(actual)).toEqual(["A", "B", "C"]);
+});
+
 test("rebase_order reverses stack order", () => {
   const commit_range = range(["A", "B", "C"]);
   const actual = CommitMetadata.rebase_order(commit_range);

src/core/CommitMetadata.ts

@@ -331,7 +331,46 @@ export async function range(commit_group_map?: CommitGroupMap) {
 }
 
 export function stack_order(commit_range: CommitRange): CommitGroupList {
-  return [...commit_range.group_list];
+  const group_by_id = new Map(commit_range.group_list.map((group) => [group.id, group]));
+  const children_by_base = new Map<string, CommitGroupList>();
+
+  for (const group of commit_range.group_list) {
+    if (!group.base || !group_by_id.has(group.base)) {
+      continue;
+    }
+
+    const children = children_by_base.get(group.base) || [];
+    children.push(group);
+    children_by_base.set(group.base, children);
+  }
+
+  const ordered_group_list: CommitGroupList = [];
+  const visited = new Set<string>();
+
+  function visit(group: CommitGroupList[number]) {
+    if (visited.has(group.id)) {
+      return;
+    }
+
+    visited.add(group.id);
+    ordered_group_list.push(group);
+
+    for (const child of children_by_base.get(group.id) || []) {
+      visit(child);
+    }
+  }
+
+  for (const group of commit_range.group_list) {
+    if (!group.base || !group_by_id.has(group.base)) {
+      visit(group);
+    }
+  }
+
+  for (const group of commit_range.group_list) {
+    visit(group);
+  }
+
+  return ordered_group_list;
 }
 
 export function rebase_order(commit_range: CommitRange): CommitGroupList {