feat: the greeting varies, and one TODO closed against its own instruction

Four time bands rather than three — someone revising at 2am is not
having an evening — and the wording is keyed on the date, so it differs
when you come back and holds steady while you are here. A line that
changes under the reader on re-render looks like a glitch, not warmth.

Also closed: "References with in-text superscript markers". That was on
the list against an explicit instruction — "with refernec, but you dont
need in text reference". Leaving it open would have meant building it
eventually.

Frontend 293/293.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TqXevQJhxFrM7jJg82cgZN

docs/TODO.md

@@ -115,7 +115,9 @@ Captured so nothing is lost while the article writing runs.
       bank, answered correctly, average score.
 - [x] **The old performance card is gone** — a per-quiz graph needing two
       attempts, superseded by the session analysis.
-- [ ] **Vary the greeting** rather than one fixed line.
+- [x] **Vary the greeting** — done 2026-09-11. Four time bands including
+      the small hours, keyed on the date so it holds for a visit and differs
+      between days rather than changing under the reader mid-render.
 
 ### Questions I owe an answer to
 - [x] **What extracted the PDFs?** PyMuPDF (`fitz`) in `pdf_service.py`, with an
@@ -204,9 +206,10 @@ Captured so nothing is lost while the article writing runs.
 - [x] **Library browsed column by column** — done 2026-09-10. The articles page
       is now the column browser itself: topics and the articles filed under them
       share a column, separated by icon. Search still answers with a flat list.
-- [ ] **References** — a section titled "References" is pinned last and styled,
-      but the numbered list with superscript markers linking down to it is not
-      built.
+- [x] **References** — a section titled "References" is pinned last and styled.
+      The numbered list with in-text superscript markers is deliberately NOT
+      built: "with refernec, but you dont need in text reference". Closing this
+      rather than leaving it open against an instruction.
 - [ ] **Per-section notes and feedback** — a learner's own note attached to a
       section, and a feedback channel to the educator.
 - [ ] **High-yield / key-exam-info toggles** — mark spans and let the reader show

frontend/src/pages/DashboardPage.jsx

@@ -6,9 +6,30 @@ import LineChart from '../components/LineChart'
 import MyNote from '../components/MyNote'
 import { useAuth } from '../context/AuthContext'
 
-function greeting(name) {
-  const h = new Date().getHours()
-  const time = h < 12 ? 'Good morning' : h < 17 ? 'Good afternoon' : 'Good evening'
+/**
+ * The line at the top of the dashboard.
+ *
+ * One fixed greeting every visit is the kind of thing that stops being read
+ * after a week. These vary by the day rather than by the render, so it is
+ * different when you come back and stable while you are here — a line that
+ * changes under you as the page re-renders reads as a glitch, not as warmth.
+ * Late-night and early-morning get their own, because someone revising at
+ * 2am is not having an evening.
+ */
+const GREETINGS = {
+  night: ['Still up', 'Burning the midnight oil', 'Late one'],
+  morning: ['Good morning', 'Morning', 'Bright and early'],
+  afternoon: ['Good afternoon', 'Afternoon', 'Hello again'],
+  evening: ['Good evening', 'Evening', 'Winding down'],
+}
+
+export function greeting(name, now = new Date()) {
+  const h = now.getHours()
+  const slot = h < 5 ? 'night' : h < 12 ? 'morning' : h < 17 ? 'afternoon' : h < 22 ? 'evening' : 'night'
+  const options = GREETINGS[slot]
+  // Keyed on the date, so it holds for the whole visit.
+  const day = Math.floor(now.getTime() / 86400000)
+  const time = options[day % options.length]
   const first = name?.split(' ')[0] || ''
   return `${time}${first ? `, ${first}` : ''}`
 }

frontend/src/pages/greeting.test.js

@@ -0,0 +1,27 @@
+import { describe, expect, it } from 'vitest'
+import { greeting } from './DashboardPage'
+
+const at = (hour, day = 15) => new Date(2026, 8, day, hour, 0, 0)
+
+describe('the dashboard greeting', () => {
+  it('fits the hour, including the small hours', () => {
+    expect(greeting('Ada', at(2))).toMatch(/Still up|midnight|Late one/)
+    expect(greeting('Ada', at(9))).toMatch(/[Mm]orning|Bright/)
+    expect(greeting('Ada', at(14))).toMatch(/[Aa]fternoon|Hello/)
+    expect(greeting('Ada', at(19))).toMatch(/[Ee]vening|Winding/)
+    expect(greeting('Ada', at(23))).toMatch(/Still up|midnight|Late one/)
+  })
+
+  it('uses the first name only, and copes without one', () => {
+    expect(greeting('Ada Lovelace', at(9))).toMatch(/, Ada$/)
+    expect(greeting('', at(9))).not.toContain(',')
+    expect(greeting(undefined, at(9))).not.toContain(',')
+  })
+
+  it('holds steady through a visit but differs between days', () => {
+    // Same day, different minutes: the line must not change under the reader.
+    expect(greeting('Ada', at(9))).toBe(greeting('Ada', new Date(2026, 8, 15, 9, 45)))
+    const week = new Set([15, 16, 17, 18, 19].map(d => greeting('Ada', at(9, d))))
+    expect(week.size).toBeGreaterThan(1)
+  })
+})