feat(domain): allocation rules become a dated series

Post.standingRule becomes Post.rules: RuleVersion[], resolved by ruleAt() as
the last version effective at or before a month. Per-month overrides still win
outright; a post with no applicable version allocates zero rather than
applying its earliest rule backwards.

allocationFor keeps its signature, so the fold, the views and the ODS export
are untouched. Settings gets a read-only rule summary for now; the history
editor follows.

src/store/actions.test.ts

@@ -77,34 +77,16 @@ describe("months", () => {
 describe("posts", () => {
   test("addPost appends with the next order value", () => {
     const data = draft();
-    const post = actions.addPost(data, "Travel", "EUR", {
-      kind: "percentOfIncome",
-      percent: 5,
-    });
+    const post = actions.addPost(data, "Travel", "EUR");
     expect(post.order).toBe(3);
     expect(post.archived).toBe(false);
     expect(data.posts).toHaveLength(4);
   });
 
-  test("addPost rounds a fixed standing rule's amount and a percent's percent", () => {
+  test("addPost starts the post unbudgeted", () => {
     const data = draft();
-    const fixedPost = actions.addPost(data, "Rent", "DKK", {
-      kind: "fixed",
-      amount: { amount: 12.345, currency: "DKK" },
-    });
-    expect(fixedPost.standingRule).toEqual({
-      kind: "fixed",
-      amount: { amount: 12.35, currency: "DKK" },
-    });
-
-    const percentPost = actions.addPost(data, "Travel", "EUR", {
-      kind: "percentOfIncome",
-      percent: 12.3456,
-    });
-    expect(percentPost.standingRule).toEqual({
-      kind: "percentOfIncome",
-      percent: 12.35,
-    });
+    const post = actions.addPost(data, "Travel", "EUR");
+    expect(post.rules).toEqual([]);
   });
 
   test("setPostArchived toggles without deleting", () => {
@@ -140,26 +122,6 @@ describe("posts", () => {
     expect(post.currency).toBe("DKK");
   });
 
-  test("updatePost rounds a fixed standing rule's amount and a percent's percent", () => {
-    const data = draft();
-    const postId = data.posts[0]!.id;
-    actions.updatePost(data, postId, {
-      standingRule: { kind: "fixed", amount: { amount: 12.345, currency: "DKK" } },
-    });
-    expect(data.posts.find((p) => p.id === postId)!.standingRule).toEqual({
-      kind: "fixed",
-      amount: { amount: 12.35, currency: "DKK" },
-    });
-
-    actions.updatePost(data, postId, {
-      standingRule: { kind: "percentOfIncome", percent: 12.3456 },
-    });
-    expect(data.posts.find((p) => p.id === postId)!.standingRule).toEqual({
-      kind: "percentOfIncome",
-      percent: 12.35,
-    });
-  });
-
   test("an unknown post id throws", () => {
     expect(() => actions.updatePost(draft(), "ghost", { name: "x" })).toThrow(/ghost/);
   });

src/store/actions.ts

@@ -102,19 +102,14 @@ export function setRuleOverride(
   month.ruleOverrides[postId] = roundRule(rule);
 }
 
-export function addPost(
-  draft: Dataset,
-  name: string,
-  currency: Currency,
-  standingRule: Rule,
-): Post {
+export function addPost(draft: Dataset, name: string, currency: Currency): Post {
   const post: Post = {
     id: newId(),
     name,
     order: draft.posts.length,
     archived: false,
     currency,
-    standingRule: roundRule(standingRule),
+    rules: [],
   };
   draft.posts.push(post);
   return post;
@@ -127,9 +122,6 @@ export function updatePost(
 ): void {
   const post = requirePost(draft, postId);
   const resolved: Partial<Omit<Post, "id">> = { ...changes };
-  if (changes.standingRule) {
-    resolved.standingRule = roundRule(changes.standingRule);
-  }
   Object.assign(post, resolved);
 }