feat(linking): explicit [#42] card references

src/lib/linking/reference.test.ts

@@ -0,0 +1,50 @@
+import { describe, it, expect } from "vitest";
+import { extractCardReference } from "@/lib/linking/reference";
+
+describe("extractCardReference", () => {
+  it("finds a bracketed reference at the end of the subject", () => {
+    expect(extractCardReference("feat(stock): inline qty editing [#42]")).toBe(42);
+  });
+
+  it("finds one anywhere in the message, including the body", () => {
+    expect(extractCardReference("[#7] fix: thing")).toBe(7);
+    expect(extractCardReference("fix: thing\n\nRefs [#7]\n")).toBe(7);
+  });
+
+  it("returns null when there is none", () => {
+    expect(extractCardReference("feat(stock): inline qty editing")).toBeNull();
+    expect(extractCardReference("")).toBeNull();
+  });
+
+  it("ignores a bare #42 without brackets", () => {
+    // Bare hashes appear constantly in prose — colours, issue numbers from
+    // other systems, ordinals. Requiring brackets makes the reference a
+    // deliberate act rather than a guess.
+    expect(extractCardReference("fix: matches #42 in the old tracker")).toBeNull();
+    expect(extractCardReference("style: use #ff8a5c")).toBeNull();
+  });
+
+  it("takes the first reference when several appear", () => {
+    // One commit links to at most one card, so a second reference cannot be
+    // honoured. First wins, deterministically.
+    expect(extractCardReference("fix: thing [#3] and also [#9]")).toBe(3);
+  });
+
+  it("rejects zero and negative numbers", () => {
+    expect(extractCardReference("fix: thing [#0]")).toBeNull();
+    expect(extractCardReference("fix: thing [#-4]")).toBeNull();
+  });
+
+  it("rejects a non-numeric reference", () => {
+    expect(extractCardReference("fix: thing [#abc]")).toBeNull();
+    expect(extractCardReference("fix: thing [#]")).toBeNull();
+  });
+
+  it("tolerates whitespace inside the brackets", () => {
+    expect(extractCardReference("fix: thing [# 42 ]")).toBe(42);
+  });
+
+  it("rejects an absurdly large number rather than overflowing", () => {
+    expect(extractCardReference(`fix: thing [#${"9".repeat(20)}]`)).toBeNull();
+  });
+});

src/lib/linking/reference.ts

@@ -0,0 +1,27 @@
+/**
+ * Explicit card references in commit messages: `[#42]`.
+ *
+ * Brackets are required. A bare `#42` appears far too often in ordinary prose —
+ * hex colours, issue numbers from other trackers, ordinals — and a linker that
+ * guesses at those attaches work to the wrong card, which is worse than not
+ * linking it at all.
+ *
+ * This is the override, not the daily habit: scope matching carries most
+ * commits. It exists for the times auto-linking gets it wrong.
+ */
+
+/** Above this, the value is not a card number; it is a typo or an overflow. */
+const MAX_CARD_NUMBER = 1_000_000;
+
+const REFERENCE = /\[#\s*(\d+)\s*\]/;
+
+export function extractCardReference(message: string): number | null {
+  const match = REFERENCE.exec(message ?? "");
+  if (!match) return null;
+
+  const value = Number(match[1]);
+  if (!Number.isInteger(value)) return null;
+  if (value < 1 || value > MAX_CARD_NUMBER) return null;
+
+  return value;
+}