feat(auth): generated one-time passwords for new accounts

src/lib/auth/initial-password.test.ts

@@ -0,0 +1,34 @@
+import { describe, it, expect } from "vitest";
+import { ALPHABET, generateInitialPassword } from "@/lib/auth/initial-password";
+
+describe("generateInitialPassword", () => {
+  it("produces three groups of four, hyphen separated", () => {
+    expect(generateInitialPassword()).toMatch(/^[a-z0-9]{4}-[a-z0-9]{4}-[a-z0-9]{4}$/);
+  });
+
+  it("clears PocketBase's eight-character minimum", () => {
+    expect(generateInitialPassword().length).toBeGreaterThanOrEqual(8);
+  });
+
+  it("omits characters that are misread when typed from a screen", () => {
+    // The owner reads this aloud or copies it by hand into an email, so 0/O
+    // and 1/l/I must not both be possible.
+    for (const banned of ["0", "o", "1", "l", "i"]) {
+      expect(ALPHABET).not.toContain(banned);
+    }
+  });
+
+  it("draws only from the declared alphabet", () => {
+    for (let i = 0; i < 50; i++) {
+      for (const char of generateInitialPassword().replace(/-/g, "")) {
+        expect(ALPHABET).toContain(char);
+      }
+    }
+  });
+
+  it("does not repeat across calls", () => {
+    const seen = new Set<string>();
+    for (let i = 0; i < 200; i++) seen.add(generateInitialPassword());
+    expect(seen.size).toBe(200);
+  });
+});

src/lib/auth/initial-password.ts

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+/**
+ * A one-time password for a newly issued client-manager account.
+ *
+ * Generated rather than chosen, because the alternative is the owner inventing
+ * one password and reusing it for every client they onboard.
+ *
+ * Uses the Web Crypto API, not Math.random. Math.random is seeded from
+ * predictable state and is not a credential source; the two are one character
+ * apart to write and worlds apart in consequence.
+ */
+
+/**
+ * Deliberately excludes 0/o, 1/l/i and u/v — the pairs that get misread when
+ * the owner copies this into an email or reads it over the phone.
+ */
+export const ALPHABET = "23456789abcdefghjkmnpqrstwxyz";
+
+const GROUPS = 3;
+const GROUP_LENGTH = 4;
+
+export function generateInitialPassword(): string {
+  const bytes = new Uint32Array(GROUPS * GROUP_LENGTH);
+  crypto.getRandomValues(bytes);
+
+  const chars = Array.from(
+    bytes,
+    (value) => ALPHABET[value % ALPHABET.length]
+  );
+
+  const groups: string[] = [];
+  for (let i = 0; i < GROUPS; i++) {
+    groups.push(chars.slice(i * GROUP_LENGTH, (i + 1) * GROUP_LENGTH).join(""));
+  }
+
+  return groups.join("-");
+}