feat(memo): create memos on the selected calendar date (#5925)

docs/superpowers/plans/2026-05-02-calendar-date-prefill.md

@@ -0,0 +1,738 @@
+# Calendar-Date Memo Prefill — Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** When the user picks a date in the activity calendar, the home memo editor pre-fills its `createTime`/`updateTime` to that date and exposes the existing `TimestampPopover` so the user can adjust before saving. Empty calendar dates also become clickable.
+
+**Architecture:** Frontend-only. A new pure helper derives a `Date` from the `displayTime` filter; `PagedMemoList` reads `MemoFilterContext` and passes the derived `Date` into `MemoEditor` via a new `defaultCreateTime` prop; `MemoEditor` seeds its reducer state from the prop, renders the popover when the prop is set in create mode, and re-syncs on prop change. `CalendarCell` drops the `count > 0` gate on click handling.
+
+**Tech Stack:** React 18 + TypeScript, Vite 7, Vitest + jsdom + @testing-library/react, Tailwind v4, react-router. State via React Context + `useReducer`.
+
+**Spec:** `docs/superpowers/specs/2026-05-02-calendar-date-prefill-design.md`
+
+---
+
+## File map
+
+**Created**
+
+- `web/src/components/MemoEditor/utils/deriveDefaultCreateTime.ts` — pure helper `(filters, now?) => Date | undefined`.
+- `web/tests/derive-default-create-time.test.ts` — Vitest unit tests for the helper.
+- `web/tests/calendar-cell-empty-clickable.test.tsx` — RTL test that count=0 in-month cells are clickable.
+
+**Modified**
+
+- `web/src/components/ActivityCalendar/CalendarCell.tsx` — drop `day.count > 0` gate from click/interactivity/tooltip.
+- `web/src/components/MemoEditor/types/components.ts` — add `defaultCreateTime?: Date` to `MemoEditorProps`.
+- `web/src/components/MemoEditor/hooks/useMemoInit.ts` — accept optional `defaultCreateTime`; in create mode, dispatch `SET_TIMESTAMPS` to seed `{ createTime, updateTime }`.
+- `web/src/components/MemoEditor/index.tsx` — accept the new prop, pass it to `useMemoInit`, add a `useEffect` that re-syncs timestamps when the prop changes in create mode, render `TimestampPopover` when `(!memo && state.timestamps.createTime)`.
+- `web/src/components/PagedMemoList/PagedMemoList.tsx` — read `useMemoFilterContext`, derive `defaultCreateTime`, pass to `<MemoEditor>` at line ~155.
+
+---
+
+## Task 1: Pure helper `deriveDefaultCreateTimeFromFilters`
+
+**Files:**
+- Create: `web/src/components/MemoEditor/utils/deriveDefaultCreateTime.ts`
+- Test: `web/tests/derive-default-create-time.test.ts`
+
+The helper takes the `filters` array from `MemoFilterContext` plus an injectable `now`, finds any `displayTime` filter (value format `YYYY-MM-DD`, local-date — produced by `useDateFilterNavigation` which forwards the `dayjs().format("YYYY-MM-DD")` string from `CalendarDayCell.date`), and returns a `Date` of `selected_date + now's hh:mm:ss`. Returns `undefined` if no `displayTime` filter or the value is malformed.
+
+- [ ] **Step 1: Write the failing tests**
+
+Create `web/tests/derive-default-create-time.test.ts`:
+
+```ts
+import { describe, expect, it } from "vitest";
+import { deriveDefaultCreateTimeFromFilters } from "@/components/MemoEditor/utils/deriveDefaultCreateTime";
+import type { MemoFilter } from "@/contexts/MemoFilterContext";
+
+describe("deriveDefaultCreateTimeFromFilters", () => {
+  const now = new Date(2026, 4, 2, 14, 32, 10); // 2026-05-02 14:32:10 local
+
+  it("returns undefined when no filters are set", () => {
+    expect(deriveDefaultCreateTimeFromFilters([], now)).toBeUndefined();
+  });
+
+  it("returns undefined when no displayTime filter is present", () => {
+    const filters: MemoFilter[] = [
+      { factor: "tagSearch", value: "work" },
+      { factor: "pinned", value: "true" },
+    ];
+    expect(deriveDefaultCreateTimeFromFilters(filters, now)).toBeUndefined();
+  });
+
+  it("merges the displayTime date with the current local hh:mm:ss", () => {
+    const filters: MemoFilter[] = [{ factor: "displayTime", value: "2025-05-01" }];
+    const result = deriveDefaultCreateTimeFromFilters(filters, now);
+    expect(result).toBeDefined();
+    expect(result!.getFullYear()).toBe(2025);
+    expect(result!.getMonth()).toBe(4); // May (0-indexed)
+    expect(result!.getDate()).toBe(1);
+    expect(result!.getHours()).toBe(14);
+    expect(result!.getMinutes()).toBe(32);
+    expect(result!.getSeconds()).toBe(10);
+  });
+
+  it("ignores extra non-displayTime filters", () => {
+    const filters: MemoFilter[] = [
+      { factor: "tagSearch", value: "work" },
+      { factor: "displayTime", value: "2025-05-01" },
+      { factor: "pinned", value: "true" },
+    ];
+    const result = deriveDefaultCreateTimeFromFilters(filters, now);
+    expect(result?.getDate()).toBe(1);
+  });
+
+  it("returns undefined for a malformed YYYY-MM-DD value", () => {
+    const cases: MemoFilter[][] = [
+      [{ factor: "displayTime", value: "not-a-date" }],
+      [{ factor: "displayTime", value: "2025-13-40" }],
+      [{ factor: "displayTime", value: "" }],
+      [{ factor: "displayTime", value: "2025-5-1" }], // single-digit month/day
+    ];
+    for (const filters of cases) {
+      expect(deriveDefaultCreateTimeFromFilters(filters, now)).toBeUndefined();
+    }
+  });
+
+  it("uses real `new Date()` when `now` is omitted", () => {
+    const filters: MemoFilter[] = [{ factor: "displayTime", value: "2025-05-01" }];
+    const before = new Date();
+    const result = deriveDefaultCreateTimeFromFilters(filters);
+    const after = new Date();
+    expect(result).toBeDefined();
+    // Time-of-day should fall between before and after (within 1s tolerance).
+    const resultTimeOnly = result!.getHours() * 3600 + result!.getMinutes() * 60 + result!.getSeconds();
+    const beforeTimeOnly = before.getHours() * 3600 + before.getMinutes() * 60 + before.getSeconds();
+    const afterTimeOnly = after.getHours() * 3600 + after.getMinutes() * 60 + after.getSeconds();
+    // Handle midnight rollover by allowing any value if before > after.
+    if (beforeTimeOnly <= afterTimeOnly) {
+      expect(resultTimeOnly).toBeGreaterThanOrEqual(beforeTimeOnly);
+      expect(resultTimeOnly).toBeLessThanOrEqual(afterTimeOnly);
+    }
+  });
+});
+```
+
+- [ ] **Step 2: Run tests to verify they fail**
+
+Run: `cd web && pnpm test derive-default-create-time`
+Expected: FAIL — module `@/components/MemoEditor/utils/deriveDefaultCreateTime` does not exist.
+
+- [ ] **Step 3: Implement the helper**
+
+Create `web/src/components/MemoEditor/utils/deriveDefaultCreateTime.ts`:
+
+```ts
+import type { MemoFilter } from "@/contexts/MemoFilterContext";
+
+const DATE_RE = /^(\d{4})-(\d{2})-(\d{2})$/;
+
+/**
+ * Derive a default `createTime` for a new memo from the active memo filters.
+ * If a `displayTime:YYYY-MM-DD` filter is present, returns that local date
+ * combined with `now`'s wall-clock hh:mm:ss. Returns undefined otherwise or
+ * when the filter value is malformed.
+ */
+export function deriveDefaultCreateTimeFromFilters(
+  filters: MemoFilter[],
+  now: Date = new Date(),
+): Date | undefined {
+  const dateFilter = filters.find((f) => f.factor === "displayTime");
+  if (!dateFilter) return undefined;
+  const match = DATE_RE.exec(dateFilter.value);
+  if (!match) return undefined;
+  const year = Number(match[1]);
+  const month = Number(match[2]);
+  const day = Number(match[3]);
+  // Construct a local-time Date and verify the components round-trip
+  // (catches things like 2025-13-40 that JS would silently roll forward).
+  const candidate = new Date(year, month - 1, day, now.getHours(), now.getMinutes(), now.getSeconds());
+  if (
+    candidate.getFullYear() !== year ||
+    candidate.getMonth() !== month - 1 ||
+    candidate.getDate() !== day
+  ) {
+    return undefined;
+  }
+  return candidate;
+}
+```
+
+- [ ] **Step 4: Run tests to verify they pass**
+
+Run: `cd web && pnpm test derive-default-create-time`
+Expected: PASS — all 6 cases.
+
+- [ ] **Step 5: Run lint**
+
+Run: `cd web && pnpm lint`
+Expected: PASS (TypeScript + Biome happy).
+
+- [ ] **Step 6: Commit**
+
+```bash
+git add web/src/components/MemoEditor/utils/deriveDefaultCreateTime.ts web/tests/derive-default-create-time.test.ts
+git commit -m "feat(memo-editor): add deriveDefaultCreateTimeFromFilters helper"
+```
+
+---
+
+## Task 2: Make empty calendar cells clickable
+
+**Files:**
+- Modify: `web/src/components/ActivityCalendar/CalendarCell.tsx`
+- Test: `web/tests/calendar-cell-empty-clickable.test.tsx`
+
+`CalendarCell` currently gates `handleClick`, `isInteractive`, and `shouldShowTooltip` on `day.count > 0`. Drop those gates so any in-month cell is clickable when `onClick` is provided. Out-of-month cells (early-returned at line ~38) stay unclickable.
+
+- [ ] **Step 1: Write the failing test**
+
+Create `web/tests/calendar-cell-empty-clickable.test.tsx`:
+
+```tsx
+import { fireEvent, render, screen } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import { CalendarCell } from "@/components/ActivityCalendar/CalendarCell";
+import type { CalendarDayCell } from "@/components/ActivityCalendar/types";
+
+const makeDay = (overrides: Partial<CalendarDayCell> = {}): CalendarDayCell => ({
+  date: "2025-05-01",
+  label: "1",
+  count: 0,
+  isCurrentMonth: true,
+  isToday: false,
+  isSelected: false,
+  ...overrides,
+});
+
+describe("CalendarCell empty-day clickability", () => {
+  it("fires onClick for an in-month day with count=0", () => {
+    const onClick = vi.fn();
+    render(<CalendarCell day={makeDay()} maxCount={5} tooltipText="May 1, 2025" onClick={onClick} />);
+
+    const button = screen.getByRole("button", { name: /May 1, 2025/ });
+    fireEvent.click(button);
+
+    expect(onClick).toHaveBeenCalledWith("2025-05-01");
+  });
+
+  it("renders an empty in-month day as interactive (tabIndex 0, not aria-disabled)", () => {
+    render(<CalendarCell day={makeDay()} maxCount={5} tooltipText="May 1, 2025" onClick={() => {}} />);
+
+    const button = screen.getByRole("button", { name: /May 1, 2025/ });
+    expect(button).toHaveAttribute("tabindex", "0");
+    expect(button).toHaveAttribute("aria-disabled", "false");
+  });
+
+  it("still renders a populated in-month day as interactive", () => {
+    const onClick = vi.fn();
+    render(<CalendarCell day={makeDay({ count: 3 })} maxCount={5} tooltipText="May 1, 2025" onClick={onClick} />);
+
+    fireEvent.click(screen.getByRole("button", { name: /May 1, 2025/ }));
+    expect(onClick).toHaveBeenCalledWith("2025-05-01");
+  });
+
+  it("does not render out-of-month days as interactive (no role=button)", () => {
+    render(
+      <CalendarCell
+        day={makeDay({ isCurrentMonth: false })}
+        maxCount={5}
+        tooltipText="May 1, 2025"
+        onClick={() => {}}
+      />,
+    );
+
+    expect(screen.queryByRole("button")).toBeNull();
+  });
+});
+```
+
+- [ ] **Step 2: Run test to verify it fails**
+
+Run: `cd web && pnpm test calendar-cell-empty-clickable`
+Expected: FAIL — first two tests fail because the empty cell currently has `tabindex="-1"`, `aria-disabled="true"`, and `onClick` is not invoked.
+
+- [ ] **Step 3: Edit `CalendarCell.tsx` to drop the count gate**
+
+Modify `web/src/components/ActivityCalendar/CalendarCell.tsx`. Three edits:
+
+(a) Replace `handleClick`:
+
+```tsx
+  const handleClick = () => {
+    if (onClick) {
+      onClick(day.date);
+    }
+  };
+```
+
+(b) Replace `isInteractive`:
+
+```tsx
+  const isInteractive = Boolean(onClick);
+```
+
+(c) Replace `shouldShowTooltip`:
+
+```tsx
+  const shouldShowTooltip = tooltipText && !disableTooltip;
+```
+
+Leave the out-of-month early return (`if (!day.isCurrentMonth) { ... }`) untouched — out-of-month cells remain non-buttons.
+
+- [ ] **Step 4: Run test to verify it passes**
+
+Run: `cd web && pnpm test calendar-cell-empty-clickable`
+Expected: PASS — all 4 cases.
+
+- [ ] **Step 5: Run the full test suite to catch regressions**
+
+Run: `cd web && pnpm test`
+Expected: PASS. The existing `activity-calendar-tooltip.test.ts` covers `getTooltipText` (a separate utility) and shouldn't be affected.
+
+- [ ] **Step 6: Run lint**
+
+Run: `cd web && pnpm lint`
+Expected: PASS.
+
+- [ ] **Step 7: Commit**
+
+```bash
+git add web/src/components/ActivityCalendar/CalendarCell.tsx web/tests/calendar-cell-empty-clickable.test.tsx
+git commit -m "feat(activity-calendar): allow clicking empty in-month dates"
+```
+
+---
+
+## Task 3: Add `defaultCreateTime` prop to `MemoEditorProps`
+
+**Files:**
+- Modify: `web/src/components/MemoEditor/types/components.ts`
+
+Type-only change. No tests at this step — TypeScript compiler is the gate. Subsequent tasks consume the prop.
+
+- [ ] **Step 1: Add the prop**
+
+Modify `web/src/components/MemoEditor/types/components.ts`. Replace the `MemoEditorProps` interface (lines 6–16) with:
+
+```ts
+export interface MemoEditorProps {
+  className?: string;
+  cacheKey?: string;
+  placeholder?: string;
+  /** Existing memo to edit. When provided, the editor initializes from it without fetching. */
+  memo?: Memo;
+  parentMemoName?: string;
+  autoFocus?: boolean;
+  /**
+   * Default `createTime` for a *new* memo (create mode only). When set, the
+   * editor seeds both `createTime` and `updateTime` to this value and renders
+   * the timestamp popover so the user can adjust before saving. Tracked live:
+   * if the prop changes after mount, the editor's timestamps re-sync. Ignored
+   * in edit mode (when `memo` is set).
+   */
+  defaultCreateTime?: Date;
+  onConfirm?: (memoName: string) => void;
+  onCancel?: () => void;
+}
+```
+
+- [ ] **Step 2: Verify compilation**
+
+Run: `cd web && pnpm lint`
+Expected: PASS (no consumer changes yet, prop is optional).
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add web/src/components/MemoEditor/types/components.ts
+git commit -m "feat(memo-editor): add defaultCreateTime prop type"
+```
+
+---
+
+## Task 4: Seed editor timestamps in `useMemoInit` (create mode)
+
+**Files:**
+- Modify: `web/src/components/MemoEditor/hooks/useMemoInit.ts`
+
+`useMemoInit` currently handles edit mode (`if (memo)`) by calling `memoService.fromMemo(memo)` and `actions.initMemo(...)`. In create mode it only restores cached content and sets default visibility — it never touches timestamps. Extend the create branch so that when `defaultCreateTime` is set, it dispatches `SET_TIMESTAMPS` with `{ createTime: defaultCreateTime, updateTime: defaultCreateTime }`. This handles the *initial mount* case.
+
+- [ ] **Step 1: Update `UseMemoInitOptions` and `useMemoInit`**
+
+Modify `web/src/components/MemoEditor/hooks/useMemoInit.ts`. Replace the entire file with:
+
+```ts
+import { useEffect, useRef, useState } from "react";
+import type { Memo, Visibility } from "@/types/proto/api/v1/memo_service_pb";
+import type { EditorRefActions } from "../Editor";
+import { cacheService, memoService } from "../services";
+import { useEditorContext } from "../state";
+
+interface UseMemoInitOptions {
+  editorRef: React.RefObject<EditorRefActions | null>;
+  memo?: Memo;
+  cacheKey?: string;
+  username: string;
+  autoFocus?: boolean;
+  defaultVisibility?: Visibility;
+  defaultCreateTime?: Date;
+}
+
+export const useMemoInit = ({
+  editorRef,
+  memo,
+  cacheKey,
+  username,
+  autoFocus,
+  defaultVisibility,
+  defaultCreateTime,
+}: UseMemoInitOptions) => {
+  const { actions, dispatch } = useEditorContext();
+  const initializedRef = useRef(false);
+  const [isInitialized, setIsInitialized] = useState(false);
+
+  useEffect(() => {
+    if (initializedRef.current) return;
+    initializedRef.current = true;
+    const key = cacheService.key(username, cacheKey);
+
+    if (memo) {
+      const initialState = memoService.fromMemo(memo);
+      cacheService.clear(key);
+      dispatch(actions.initMemo(initialState));
+    } else {
+      const cachedContent = cacheService.load(key);
+      if (cachedContent) {
+        dispatch(actions.updateContent(cachedContent));
+      }
+      if (defaultVisibility !== undefined) {
+        dispatch(actions.setMetadata({ visibility: defaultVisibility }));
+      }
+      if (defaultCreateTime) {
+        dispatch(actions.setTimestamps({ createTime: defaultCreateTime, updateTime: defaultCreateTime }));
+      }
+    }
+
+    if (autoFocus) {
+      setTimeout(() => editorRef.current?.focus(), 100);
+    }
+
+    setIsInitialized(true);
+  }, [memo, cacheKey, username, autoFocus, defaultVisibility, defaultCreateTime, actions, dispatch, editorRef]);
+
+  return { isInitialized };
+};
+```
+
+Notes:
+- The `defaultCreateTime` dependency is added to the effect's deps to satisfy the linter, but `initializedRef` ensures the body runs only once. Live re-sync after mount is handled by a separate effect in Task 5.
+- Edit mode is unchanged — `defaultCreateTime` is intentionally ignored when `memo` is set.
+
+- [ ] **Step 2: Verify compilation**
+
+Run: `cd web && pnpm lint`
+Expected: PASS.
+
+- [ ] **Step 3: Commit**
+
+```bash
+git add web/src/components/MemoEditor/hooks/useMemoInit.ts
+git commit -m "feat(memo-editor): seed timestamps from defaultCreateTime on init"
+```
+
+---
+
+## Task 5: Wire `defaultCreateTime` through `MemoEditor` and render popover
+
+**Files:**
+- Modify: `web/src/components/MemoEditor/index.tsx`
+
+Three changes:
+1. Destructure `defaultCreateTime` from props.
+2. Pass it into `useMemoInit`.
+3. Add a `useEffect` that dispatches `setTimestamps` whenever `defaultCreateTime` changes after mount (live re-sync per design Q3-A). Skip when `memo` is set.
+4. Update the popover render condition so it shows in create mode too when timestamps are seeded.
+
+- [ ] **Step 1: Destructure the prop and pass it to `useMemoInit`**
+
+In `web/src/components/MemoEditor/index.tsx`, update the `MemoEditorImpl` destructuring (around line 42):
+
+```tsx
+const MemoEditorImpl: React.FC<MemoEditorProps> = ({
+  className,
+  cacheKey,
+  memo,
+  parentMemoName,
+  autoFocus,
+  placeholder,
+  defaultCreateTime,
+  onConfirm,
+  onCancel,
+}) => {
+```
+
+And update the `useMemoInit` call (around line 71):
+
+```tsx
+const { isInitialized } = useMemoInit({
+  editorRef,
+  memo,
+  cacheKey,
+  username: currentUser?.name ?? "",
+  autoFocus,
+  defaultVisibility,
+  defaultCreateTime,
+});
+```
+
+- [ ] **Step 2: Add the live re-sync effect**
+
+In the same file, add a new `useEffect` after `useMemoInit` (and after `useAutoSave`) that re-syncs timestamps when `defaultCreateTime` changes in create mode. Place it just before the existing `useEffect` that fetches AI settings (around line 80):
+
+```tsx
+// Live-sync the draft's createTime/updateTime to the calendar-derived prop.
+// Only applies in create mode; edit mode owns its own timestamps. Runs after
+// initial mount (the seed value is set in useMemoInit), and again whenever
+// the prop changes — e.g., when the user picks a different calendar date
+// while the editor is open.
+useEffect(() => {
+  if (memo) return;
+  if (!isInitialized) return;
+  dispatch(
+    actions.setTimestamps({
+      createTime: defaultCreateTime,
+      updateTime: defaultCreateTime,
+    }),
+  );
+}, [defaultCreateTime, memo, isInitialized, actions, dispatch]);
+```
+
+Notes:
+- We pass `undefined` through when the prop becomes undefined (filter cleared) — this resets timestamps to undefined so the editor falls back to "server-stamped now" on save, exactly the pre-feature behavior.
+- The `isInitialized` guard avoids racing with `useMemoInit`'s one-shot seed.
+
+- [ ] **Step 3: Update the popover render condition**
+
+In the same file, find the existing block (around line 294):
+
+```tsx
+{memoName && (
+  <div className="w-full -mb-1">
+    <TimestampPopover />
+  </div>
+)}
+```
+
+Replace with:
+
+```tsx
+{(memoName || (!memo && state.timestamps.createTime)) && (
+  <div className="w-full -mb-1">
+    <TimestampPopover />
+  </div>
+)}
+```
+
+Now the popover renders in edit mode (unchanged) AND in create mode whenever a default timestamp has been seeded.
+
+- [ ] **Step 4: Verify compilation**
+
+Run: `cd web && pnpm lint`
+Expected: PASS.
+
+- [ ] **Step 5: Run all tests**
+
+Run: `cd web && pnpm test`
+Expected: PASS (no editor-specific tests added; existing tests continue to pass).
+
+- [ ] **Step 6: Commit**
+
+```bash
+git add web/src/components/MemoEditor/index.tsx
+git commit -m "feat(memo-editor): live-sync timestamps and reveal popover from defaultCreateTime"
+```
+
+---
+
+## Task 6: Wire calendar selection through `PagedMemoList`
+
+**Files:**
+- Modify: `web/src/components/PagedMemoList/PagedMemoList.tsx`
+
+The home memo editor is rendered at line ~155 of `PagedMemoList.tsx`. Read the current `MemoFilterContext` filters, derive the `defaultCreateTime`, and pass it to `<MemoEditor>`. Wrap in `useMemo` so the reference stays stable when filters don't change (avoids re-firing the live-sync effect).
+
+- [ ] **Step 1: Add the imports and derivation**
+
+Modify `web/src/components/PagedMemoList/PagedMemoList.tsx`. Add to the existing imports near the top:
+
+```tsx
+import { useMemo } from "react";
+import { useMemoFilterContext } from "@/contexts/MemoFilterContext";
+import { deriveDefaultCreateTimeFromFilters } from "@/components/MemoEditor/utils/deriveDefaultCreateTime";
+```
+
+If `useMemo` is already imported from `react` in this file, merge into the existing import rather than duplicating.
+
+Inside the component body (above the `children` JSX, near the top of the function), add:
+
+```tsx
+const { filters } = useMemoFilterContext();
+const defaultCreateTime = useMemo(
+  () => deriveDefaultCreateTimeFromFilters(filters),
+  [filters],
+);
+```
+
+- [ ] **Step 2: Pass the prop to `<MemoEditor>`**
+
+Replace the existing line ~155:
+
+```tsx
+{showMemoEditor ? <MemoEditor className="mb-2" cacheKey="home-memo-editor" placeholder={t("editor.any-thoughts")} /> : null}
+```
+
+with:
+
+```tsx
+{showMemoEditor ? (
+  <MemoEditor
+    className="mb-2"
+    cacheKey="home-memo-editor"
+    placeholder={t("editor.any-thoughts")}
+    defaultCreateTime={defaultCreateTime}
+  />
+) : null}
+```
+
+- [ ] **Step 3: Verify compilation**
+
+Run: `cd web && pnpm lint`
+Expected: PASS.
+
+- [ ] **Step 4: Run all tests**
+
+Run: `cd web && pnpm test`
+Expected: PASS.
+
+- [ ] **Step 5: Commit**
+
+```bash
+git add web/src/components/PagedMemoList/PagedMemoList.tsx
+git commit -m "feat(home): pass calendar-selected date as default createTime to memo editor"
+```
+
+---
+
+## Task 7: Manual smoke test
+
+No code changes. Per `CLAUDE.md`: "For UI or frontend changes, start the dev server and use the feature in a browser before reporting the task as complete." Walk through the user-visible flows.
+
+- [ ] **Step 1: Start the backend and frontend**
+
+In one terminal:
+```bash
+go run ./cmd/memos --port 8081
+```
+
+In another:
+```bash
+cd web && pnpm dev
+```
+
+Open `http://localhost:3001`.
+
+- [ ] **Step 2: Smoke — populated past date**
+
+1. Sign in. Confirm the activity calendar is visible (statistics view).
+2. Click a *past* date that already has memos.
+3. Confirm the URL gains `?filter=displayTime:YYYY-MM-DD`.
+4. Confirm the home memo editor shows the timestamp popover above the textarea, populated with the selected date.
+5. Type a memo and click Save.
+6. Clear the date filter (chip X). Reapply by clicking the same date.
+7. Confirm the new memo appears under that date.
+
+- [ ] **Step 3: Smoke — empty past date**
+
+1. Pick a past date with **zero memos** in the calendar (lightest cell).
+2. Confirm it is now clickable, the URL filter applies, and the empty-state shows.
+3. Type and save a memo.
+4. Confirm the memo appears for that date and the calendar cell tints up.
+
+- [ ] **Step 4: Smoke — future date**
+
+1. Click a future date in the current month.
+2. Confirm the popover shows that date.
+3. Save a memo. Confirm it appears under that date.
+
+- [ ] **Step 5: Smoke — clear filter mid-draft**
+
+1. Pick May 1 (or any non-today date). Type some content, do **not** save.
+2. Click the filter chip X to clear the date filter.
+3. Confirm the popover disappears and the draft content is preserved (autoSave behavior).
+4. Save and confirm the memo gets a server-stamped "now" timestamp (i.e., appears under today).
+
+- [ ] **Step 6: Smoke — change filter mid-draft**
+
+1. Pick May 1. Type content.
+2. Without saving, click May 3.
+3. Confirm the popover updates to May 3.
+4. Save. Confirm the memo appears under May 3.
+
+- [ ] **Step 7: Smoke — comment editor unaffected**
+
+1. Open any memo's detail view (or open the comments thread).
+2. Confirm the reply editor does **not** show a timestamp popover.
+3. Confirm the date filter has no visible effect on the reply editor.
+
+- [ ] **Step 8: Smoke — edit mode unaffected**
+
+1. Edit an existing memo (pencil icon).
+2. Confirm the existing timestamp popover still works exactly as before, regardless of any active calendar filter.
+
+- [ ] **Step 9: Smoke — empty-date click on Explore page**
+
+1. Navigate to the Explore page (which also renders the calendar).
+2. Click an empty date.
+3. Confirm the URL filter applies and the empty-state shows. (No editor on Explore — that's correct.)
+
+- [ ] **Step 10: Record results**
+
+Note any unexpected behavior (especially: selection-ring contrast on the lowest-intensity background, mentioned as a flag in the spec). If the ring is too subtle, file a follow-up — *not* part of this plan.
+
+---
+
+## Self-review
+
+**Spec coverage check:**
+
+| Spec requirement | Task |
+|---|---|
+| Empty calendar dates clickable | Task 2 |
+| Editor shows TimestampPopover in create mode when filter active | Task 5 (popover condition) |
+| `createTime` = selected date + current local hh:mm:ss | Task 1 (helper) + Task 4 (seed) |
+| `updateTime` mirrored to same value | Task 4 (seed) + Task 5 (live sync) |
+| Live-derived: filter change re-syncs timestamps | Task 5 (live-sync `useEffect`) |
+| Filter cleared → undefined → server-stamped "now" | Task 5 (passes `undefined` through) + Task 6 (helper returns undefined) |
+| Future dates allowed (no clamp) | Task 1 (no clamp in helper); confirmed in Task 7 step 4 |
+| Comment editor unaffected | Task 6 wires only `PagedMemoList`; confirmed in Task 7 step 7 |
+| Edit mode unaffected | Task 4 + 5 explicitly guard on `memo`; confirmed in Task 7 step 8 |
+| Empty-date click on Explore/Archived/Profile | Task 2 (calendar-side change); confirmed in Task 7 step 9 |
+| DST/timezone uses local time | Task 1 (`new Date(y, m-1, d, h, mi, s)`) |
+| Helper unit tests | Task 1 |
+| `CalendarCell` empty-cell test | Task 2 |
+| Manual smoke | Task 7 |
+
+All spec requirements have a task. No gaps.
+
+**Placeholder scan:** No "TBD"/"TODO" steps. Every code step shows the actual code.
+
+**Type/name consistency check:**
+- `MemoFilter` and `useMemoFilterContext` exist at `@/contexts/MemoFilterContext` (verified during exploration).
+- `editorActions.setTimestamps` exists in `state/actions.ts:75` and accepts `Partial<EditorState["timestamps"]>` (verified). Calls in Tasks 4 and 5 match.
+- `state.timestamps.createTime` is `Date | undefined` (verified `state/types.ts:27-29`). The popover render condition uses it as a truthy guard — `Date` instances are truthy, `undefined` is falsy.
+- `useMemoFilterContext` (alias used in PagedMemoList) is exported from `MemoFilterContext.tsx:151` (verified).
+- `deriveDefaultCreateTimeFromFilters` signature is identical between Task 1 (definition) and Task 6 (consumer).
+- `defaultCreateTime: Date | undefined` flows consistently through `MemoEditorProps` (Task 3) → `MemoEditorImpl` destructuring (Task 5) → `useMemoInit` options (Task 4) → reducer payloads.

docs/superpowers/specs/2026-05-02-calendar-date-prefill-design.md

@@ -0,0 +1,165 @@
+# Create memo on selected calendar date — design
+
+**Date:** 2026-05-02
+**Scope:** Frontend-only.
+
+## Problem
+
+Clicking a date in the activity calendar filters the memo list to that date but does nothing for the inline editor. To create a memo dated for the selected day, the user must (1) create with today's timestamp, then (2) open the timestamp popover on the saved memo and edit `createTime`. This is a two-step retro-fill that defeats the calendar selection. Empty dates are also not clickable today, so the user cannot start the first memo for an empty day from the calendar at all.
+
+## Goal
+
+When a user picks a calendar date and immediately writes in the home editor, the resulting memo is created on that date — single-step.
+
+## Non-goals
+
+- Backend changes. The API already accepts custom `createTime` and `updateTime`.
+- Changes to the comment/reply editor or the edit-mode editor.
+- Changes outside the home page's editor render site (Explore/Archived/Profile pages have no editor).
+- Reworking the timestamp popover UI itself.
+- Empty-state copy changes on non-Home pages when an empty date is selected.
+
+## User-visible behavior
+
+1. **Empty calendar dates are clickable.** Clicking a date with zero memos sets the `displayTime` filter the same way a populated date does. Tooltip and selection ring still work.
+2. **When the home editor renders with an active `displayTime` filter:**
+   - The `TimestampPopover` (already used in edit mode) appears in create mode, pre-populated with the selected date.
+   - The draft's `createTime` is set to **selected local date + current local hh:mm:ss** (e.g., picking May 1 at 14:32 → `2025-05-01 14:32`).
+   - The draft's `updateTime` is set to the same value, to avoid the saved memo immediately reading "updated today" relative to a back-dated `createTime`.
+   - The user can adjust either field via the popover before saving.
+3. **When no `displayTime` filter is active**, the editor is identical to today: no popover in create mode, no override, server stamps with "now".
+4. **Live derivation.** If the filter changes while a draft is in progress, the editor's prefilled timestamps re-sync to the new date. The popover stays visible so the change is observable. (Manual popover edits before the next filter change are overwritten — chosen tradeoff.)
+5. **Future dates are allowed** (e.g., May 15 when today is May 2). Backend already accepts future timestamps.
+6. **Other contexts** (Explore/Archived/Profile) gain empty-date clickability for navigation consistency, but have no editor and so no prefill behavior.
+
+## Architecture
+
+Four touch points, all in `web/src/`:
+
+| File | Change |
+|------|--------|
+| `components/ActivityCalendar/CalendarCell.tsx` | Drop `day.count > 0` gate so empty in-month cells are clickable. |
+| `components/MemoEditor/index.tsx` | Accept `defaultCreateTime?: Date` prop; render `TimestampPopover` in create mode when set; sync state on prop change. |
+| `components/MemoEditor/utils/deriveDefaultCreateTime.ts` (new) | Pure helper: `(filters, now?) => Date \| undefined` derived from any `displayTime` filter. |
+| `components/PagedMemoList/PagedMemoList.tsx` | At the home-editor render site (line 155), read `MemoFilterContext`, compute `defaultCreateTime`, pass as prop. |
+
+### Data flow
+
+```
+CalendarCell click
+  → useDateFilterNavigation
+  → URL ?filter=displayTime:YYYY-MM-DD
+  → MemoFilterContext re-renders
+  → PagedMemoList recomputes defaultCreateTime via deriveDefaultCreateTimeFromFilters(filters)
+  → <MemoEditor defaultCreateTime={...}> re-renders
+  → editor reducer syncs state.timestamps (create + update) and renders TimestampPopover
+  → save → memoService.ts:111 sends createTime/updateTime to API
+```
+
+## Component contracts
+
+### `MemoEditor` — new prop
+
+```ts
+interface MemoEditorProps {
+  // ...existing props
+  /**
+   * When set in create mode (no `memo` prop), seeds the draft's
+   * createTime/updateTime and reveals the TimestampPopover so the
+   * user can adjust. Tracked live: changes after mount re-sync state.
+   * Ignored in edit mode (when `memo` is set).
+   */
+  defaultCreateTime?: Date;
+}
+```
+
+Internal behavior:
+- On `INIT_MEMO` for create mode, if `defaultCreateTime` is set, payload `timestamps` is `{ createTime: defaultCreateTime, updateTime: defaultCreateTime }`.
+- A `useEffect` keyed on `[defaultCreateTime?.getTime(), memo]` dispatches `SET_TIMESTAMPS` whenever the prop changes in create mode.
+- Popover render condition becomes `memoName || (!memo && state.timestamps.createTime)`.
+
+### `deriveDefaultCreateTimeFromFilters` — pure helper
+
+```ts
+// web/src/components/MemoEditor/utils/deriveDefaultCreateTime.ts
+export function deriveDefaultCreateTimeFromFilters(
+  filters: MemoFilter[],
+  now: Date = new Date(),
+): Date | undefined {
+  const dateFilter = filters.find((f) => f.factor === "displayTime");
+  if (!dateFilter) return undefined;
+  const [y, m, d] = dateFilter.value.split("-").map(Number);
+  if (!y || !m || !d) return undefined;
+  return new Date(y, m - 1, d, now.getHours(), now.getMinutes(), now.getSeconds());
+}
+```
+
+Notes:
+- Defensive parse — returns `undefined` for malformed values rather than throwing.
+- `now` is injectable for deterministic tests.
+- Multiple `displayTime` filters are not produced by current UI; `find` ignores extras safely.
+
+### `PagedMemoList.tsx` — call-site change
+
+```tsx
+const { filters } = useMemoFilterContext();
+const defaultCreateTime = useMemo(
+  () => deriveDefaultCreateTimeFromFilters(filters),
+  [filters],
+);
+// ...
+{showMemoEditor ? (
+  <MemoEditor
+    className="mb-2"
+    cacheKey="home-memo-editor"
+    placeholder={t("editor.any-thoughts")}
+    defaultCreateTime={defaultCreateTime}
+  />
+) : null}
+```
+
+`useMemo` keyed on `filters` keeps the reference stable when the filter doesn't change, avoiding unnecessary editor re-syncs. `now` is captured once per filter change — matches "the local time when you picked the date".
+
+### `CalendarCell.tsx` — empty-cell clickability
+
+- `handleClick`: drop the `day.count > 0` check; just call `onClick(day.date)` if `onClick` is provided.
+- `isInteractive`: `Boolean(onClick)`.
+- `tabIndex` / `aria-disabled` / hover-cursor classes follow the new `isInteractive`.
+- `shouldShowTooltip`: drop the `day.count > 0` gate; tooltip text already conveys the count.
+- Out-of-month cells (existing early return) stay unclickable.
+- The `selected` ring already works on count=0 cells. Visual contrast on the lowest-intensity background may need a small ring-weight bump in light theme; eyeball during implementation.
+
+## Edge cases
+
+- **No filter / filter cleared:** `defaultCreateTime` becomes `undefined`; editor falls back to current behavior.
+- **User edits draft, then re-picks date:** live-derived; editor's `createTime` updates, popover reflects new value.
+- **User manually edits via popover, then changes filter:** prop sync overwrites manual edit. Acceptable per design choice; popover keeps the change observable.
+- **Draft cache (`cacheKey="home-memo-editor"`):** caches `content`, not `timestamps`. Reload restores text but `createTime` is freshly derived from current filter — consistent.
+- **Future dates:** allowed. No clamp.
+- **DST / timezone:** date arithmetic uses local time (`new Date(y, m-1, d, h, mi, s)`), matching `useDateFilterNavigation`'s local-date convention. Server receives an absolute `Timestamp`.
+- **Comment editor (`MemoCommentSection`):** doesn't pass `defaultCreateTime` → no behavior change.
+- **Edit mode (`memo` prop set):** prop is ignored; existing edit-mode popover is unchanged.
+- **Empty-date click on Explore/Archived/Profile:** filters to empty date → "no memos" empty state. Acceptable.
+
+## Testing
+
+- **Unit (Vitest)** for `deriveDefaultCreateTimeFromFilters`:
+  - no `displayTime` filter → `undefined`
+  - valid `displayTime:2025-05-01` + injected `now=14:32:10` → `2025-05-01 14:32:10` local
+  - malformed value (`"not-a-date"`, `"2025-13-40"`) → `undefined`
+  - extra non-`displayTime` filters present → still works
+- **Component (React Testing Library) for `CalendarCell`:** count=0 in-month cell is clickable, has correct `tabIndex`/`aria-disabled`, fires `onClick` with date.
+- **Component for `MemoEditor`:** with `defaultCreateTime` prop, popover renders in create mode and `state.timestamps.createTime` matches; without prop, no popover; changing the prop re-syncs state.
+- **Manual smoke (per CLAUDE.md UI-changes rule):** `pnpm dev`, click a non-today date (with and without existing memos), type a memo, save, confirm it appears under that date. Clear the filter chip; confirm a new memo posts to today.
+
+## Risks
+
+- The `useEffect` re-sync overwriting an in-progress popover edit is a *chosen* behavior. If users later complain, a "manual override sticky" flag is the natural follow-up. Not pre-built.
+- Selection-ring contrast on the lowest-intensity background may need a small visual tweak; flagged for implementation.
+
+## Out of scope (explicit)
+
+- Sticky manual-override semantics for the popover.
+- New empty-state copy on Explore/Archived/Profile when filtering to a date with zero memos.
+- Any backend/API change.
+- Any change to the comment editor, edit mode, or non-Home editor sites.

web/src/components/ActivityCalendar/CalendarCell.tsx

@@ -18,7 +18,7 @@ export const CalendarCell = memo((props: CalendarCellProps) => {
   const { day, maxCount, tooltipText, onClick, size = "default", disableTooltip = false } = props;
 
   const handleClick = () => {
-    if (day.count > 0 && onClick) {
+    if (onClick) {
       onClick(day.date);
     }
   };
@@ -32,7 +32,7 @@ export const CalendarCell = memo((props: CalendarCellProps) => {
     sizeConfig.borderRadius,
     smallExtraClasses,
   );
-  const isInteractive = Boolean(onClick && day.count > 0);
+  const isInteractive = Boolean(onClick);
   const ariaLabel = day.isSelected ? `${tooltipText} (selected)` : tooltipText;
 
   if (!day.isCurrentMonth) {
@@ -62,7 +62,7 @@ export const CalendarCell = memo((props: CalendarCellProps) => {
     </button>
   );
 
-  const shouldShowTooltip = tooltipText && day.count > 0 && !disableTooltip;
+  const shouldShowTooltip = tooltipText && !disableTooltip;
 
   if (!shouldShowTooltip) {
     return button;

web/src/components/MemoEditor/hooks/useMemoInit.ts

@@ -11,9 +11,18 @@ interface UseMemoInitOptions {
   username: string;
   autoFocus?: boolean;
   defaultVisibility?: Visibility;
+  defaultCreateTime?: Date;
 }
 
-export const useMemoInit = ({ editorRef, memo, cacheKey, username, autoFocus, defaultVisibility }: UseMemoInitOptions) => {
+export const useMemoInit = ({
+  editorRef,
+  memo,
+  cacheKey,
+  username,
+  autoFocus,
+  defaultVisibility,
+  defaultCreateTime,
+}: UseMemoInitOptions) => {
   const { actions, dispatch } = useEditorContext();
   const initializedRef = useRef(false);
   const [isInitialized, setIsInitialized] = useState(false);
@@ -35,6 +44,9 @@ export const useMemoInit = ({ editorRef, memo, cacheKey, username, autoFocus, de
       if (defaultVisibility !== undefined) {
         dispatch(actions.setMetadata({ visibility: defaultVisibility }));
       }
+      if (defaultCreateTime) {
+        dispatch(actions.setTimestamps({ createTime: defaultCreateTime, updateTime: defaultCreateTime }));
+      }
     }
 
     if (autoFocus) {
@@ -42,7 +54,7 @@ export const useMemoInit = ({ editorRef, memo, cacheKey, username, autoFocus, de
     }
 
     setIsInitialized(true);
-  }, [memo, cacheKey, username, autoFocus, defaultVisibility, actions, dispatch, editorRef]);
+  }, [memo, cacheKey, username, autoFocus, defaultVisibility, defaultCreateTime, actions, dispatch, editorRef]);
 
   return { isInitialized };
 };

web/src/components/MemoEditor/index.tsx

@@ -46,6 +46,7 @@ const MemoEditorImpl: React.FC<MemoEditorProps> = ({
   parentMemoName,
   autoFocus,
   placeholder,
+  defaultCreateTime,
   onConfirm,
   onCancel,
 }) => {
@@ -68,7 +69,15 @@ const MemoEditorImpl: React.FC<MemoEditorProps> = ({
   // Get default visibility from user settings
   const defaultVisibility = userGeneralSetting?.memoVisibility ? convertVisibilityFromString(userGeneralSetting.memoVisibility) : undefined;
 
-  const { isInitialized } = useMemoInit({ editorRef, memo, cacheKey, username: currentUser?.name ?? "", autoFocus, defaultVisibility });
+  const { isInitialized } = useMemoInit({
+    editorRef,
+    memo,
+    cacheKey,
+    username: currentUser?.name ?? "",
+    autoFocus,
+    defaultVisibility,
+    defaultCreateTime,
+  });
   const isDraftCacheEnabled = !memo;
 
   // Auto-save content to localStorage
@@ -77,6 +86,22 @@ const MemoEditorImpl: React.FC<MemoEditorProps> = ({
   // Focus mode management with body scroll lock
   useFocusMode(state.ui.isFocusMode);
 
+  // Live-sync the draft's createTime/updateTime to the calendar-derived prop.
+  // Only applies in create mode; edit mode owns its own timestamps. Runs after
+  // initial mount (the seed value is set in useMemoInit), and again whenever
+  // the prop changes — e.g., when the user picks a different calendar date
+  // while the editor is open.
+  useEffect(() => {
+    if (memo) return;
+    if (!isInitialized) return;
+    dispatch(
+      actions.setTimestamps({
+        createTime: defaultCreateTime,
+        updateTime: defaultCreateTime,
+      }),
+    );
+  }, [defaultCreateTime, memo, isInitialized, actions, dispatch]);
+
   useEffect(() => {
     if (!currentUser) {
       return;
@@ -257,6 +282,13 @@ const MemoEditorImpl: React.FC<MemoEditorProps> = ({
       if (!memoName && defaultVisibility) {
         dispatch(actions.setMetadata({ visibility: defaultVisibility }));
       }
+      // Re-seed the calendar-derived timestamps so the popover stays visible
+      // and subsequent memos in the same filter session keep the prefilled date.
+      // Without this, the live-sync effect won't re-fire (its deps don't change
+      // across reset), and memo #2 onward would silently fall back to "now".
+      if (!memoName && defaultCreateTime) {
+        dispatch(actions.setTimestamps({ createTime: defaultCreateTime, updateTime: defaultCreateTime }));
+      }
 
       // Notify parent component of successful save
       onConfirm?.(result.memoName);
@@ -291,7 +323,7 @@ const MemoEditorImpl: React.FC<MemoEditorProps> = ({
         {/* Exit button is absolutely positioned in top-right corner when active */}
         <FocusModeExitButton isActive={state.ui.isFocusMode} onToggle={handleToggleFocusMode} title={t("editor.exit-focus-mode")} />
 
-        {memoName && (
+        {(memoName || (!memo && state.timestamps.createTime)) && (
           <div className="w-full -mb-1">
             <TimestampPopover />
           </div>

web/src/components/MemoEditor/types/components.ts

@@ -11,6 +11,14 @@ export interface MemoEditorProps {
   memo?: Memo;
   parentMemoName?: string;
   autoFocus?: boolean;
+  /**
+   * Default `createTime` for a *new* memo (create mode only). When set, the
+   * editor seeds both `createTime` and `updateTime` to this value and renders
+   * the timestamp popover so the user can adjust before saving. Tracked live:
+   * if the prop changes after mount, the editor's timestamps re-sync. Ignored
+   * in edit mode (when `memo` is set).
+   */
+  defaultCreateTime?: Date;
   onConfirm?: (memoName: string) => void;
   onCancel?: () => void;
 }

web/src/components/MemoEditor/utils/deriveDefaultCreateTime.ts

@@ -0,0 +1,26 @@
+import type { MemoFilter } from "@/contexts/MemoFilterContext";
+
+const DATE_RE = /^(\d{4})-(\d{2})-(\d{2})$/;
+
+/**
+ * Derive a default `createTime` for a new memo from the active memo filters.
+ * If a `displayTime:YYYY-MM-DD` filter is present, returns that local date
+ * combined with `now`'s wall-clock hh:mm:ss. Returns undefined otherwise or
+ * when the filter value is malformed.
+ */
+export function deriveDefaultCreateTimeFromFilters(filters: MemoFilter[], now: Date = new Date()): Date | undefined {
+  const dateFilter = filters.find((f) => f.factor === "displayTime");
+  if (!dateFilter) return undefined;
+  const match = DATE_RE.exec(dateFilter.value);
+  if (!match) return undefined;
+  const year = Number(match[1]);
+  const month = Number(match[2]);
+  const day = Number(match[3]);
+  // Construct a local-time Date and verify the components round-trip
+  // (catches things like 2025-13-40 that JS would silently roll forward).
+  const candidate = new Date(year, month - 1, day, now.getHours(), now.getMinutes(), now.getSeconds());
+  if (candidate.getFullYear() !== year || candidate.getMonth() !== month - 1 || candidate.getDate() !== day) {
+    return undefined;
+  }
+  return candidate;
+}

web/src/components/PagedMemoList/PagedMemoList.tsx

@@ -2,8 +2,10 @@ import { useQueryClient } from "@tanstack/react-query";
 import { ArrowUpIcon } from "lucide-react";
 import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { MentionResolutionProvider } from "@/components/MemoContent/MentionResolutionContext";
+import { deriveDefaultCreateTimeFromFilters } from "@/components/MemoEditor/utils/deriveDefaultCreateTime";
 import { Button } from "@/components/ui/button";
 import { userServiceClient } from "@/connect";
+import { useMemoFilterContext } from "@/contexts/MemoFilterContext";
 import { DEFAULT_LIST_MEMOS_PAGE_SIZE } from "@/helpers/consts";
 import { useInfiniteMemos } from "@/hooks/useMemoQueries";
 import { userKeys } from "@/hooks/useUserQueries";
@@ -82,8 +84,10 @@ function useAutoFetchWhenNotScrollable({
 const PagedMemoList = (props: Props) => {
   const t = useTranslate();
   const queryClient = useQueryClient();
+  const { filters } = useMemoFilterContext();
 
   const showMemoEditor = props.showMemoEditor ?? false;
+  const defaultCreateTime = useMemo(() => deriveDefaultCreateTimeFromFilters(filters), [filters]);
 
   const { data, fetchNextPage, hasNextPage, isFetchingNextPage, isLoading } = useInfiniteMemos(
     {
@@ -152,7 +156,14 @@ const PagedMemoList = (props: Props) => {
           <Skeleton showCreator={props.showCreator} count={4} />
         ) : (
           <>
-            {showMemoEditor ? <MemoEditor className="mb-2" cacheKey="home-memo-editor" placeholder={t("editor.any-thoughts")} /> : null}
+            {showMemoEditor ? (
+              <MemoEditor
+                className="mb-2"
+                cacheKey="home-memo-editor"
+                placeholder={t("editor.any-thoughts")}
+                defaultCreateTime={defaultCreateTime}
+              />
+            ) : null}
             <MemoFilters />
             {sortedMemoList.map((memo) => props.renderer(memo))}
 

web/tests/calendar-cell-empty-clickable.test.tsx

@@ -0,0 +1,50 @@
+import { fireEvent, render, screen } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import { CalendarCell } from "@/components/ActivityCalendar/CalendarCell";
+import type { CalendarDayCell } from "@/components/ActivityCalendar/types";
+
+const makeDay = (overrides: Partial<CalendarDayCell> = {}): CalendarDayCell => ({
+  date: "2025-05-01",
+  label: "1",
+  count: 0,
+  isCurrentMonth: true,
+  isToday: false,
+  isSelected: false,
+  ...overrides,
+});
+
+describe("CalendarCell empty-day clickability", () => {
+  it("fires onClick for an in-month day with count=0", () => {
+    const onClick = vi.fn();
+    render(<CalendarCell day={makeDay()} maxCount={5} tooltipText="May 1, 2025" onClick={onClick} />);
+
+    const button = screen.getByRole("button", { name: /May 1, 2025/ });
+    fireEvent.click(button);
+
+    expect(onClick).toHaveBeenCalledWith("2025-05-01");
+  });
+
+  it("renders an empty in-month day as interactive (tabIndex 0, not aria-disabled)", () => {
+    render(<CalendarCell day={makeDay()} maxCount={5} tooltipText="May 1, 2025" onClick={() => {}} />);
+
+    const button = screen.getByRole("button", { name: /May 1, 2025/ });
+    expect(button).toHaveAttribute("tabindex", "0");
+    expect(button).toHaveAttribute("aria-disabled", "false");
+  });
+
+  it("still renders a populated in-month day as interactive", () => {
+    const onClick = vi.fn();
+    render(<CalendarCell day={makeDay({ count: 3 })} maxCount={5} tooltipText="May 1, 2025" onClick={onClick} />);
+
+    fireEvent.click(screen.getByRole("button", { name: /May 1, 2025/ }));
+    expect(onClick).toHaveBeenCalledWith("2025-05-01");
+  });
+
+  it("does not render out-of-month days as interactive (no role=button)", () => {
+    render(
+      <CalendarCell day={makeDay({ isCurrentMonth: false })} maxCount={5} tooltipText="May 1, 2025" onClick={() => {}} />,
+    );
+
+    expect(screen.queryByRole("button")).toBeNull();
+  });
+});

web/tests/derive-default-create-time.test.ts

@@ -0,0 +1,75 @@
+import { describe, expect, it } from "vitest";
+import { deriveDefaultCreateTimeFromFilters } from "@/components/MemoEditor/utils/deriveDefaultCreateTime";
+import type { MemoFilter } from "@/contexts/MemoFilterContext";
+
+describe("deriveDefaultCreateTimeFromFilters", () => {
+  const now = new Date(2026, 4, 2, 14, 32, 10); // 2026-05-02 14:32:10 local
+
+  it("returns undefined when no filters are set", () => {
+    expect(deriveDefaultCreateTimeFromFilters([], now)).toBeUndefined();
+  });
+
+  it("returns undefined when no displayTime filter is present", () => {
+    const filters: MemoFilter[] = [
+      { factor: "tagSearch", value: "work" },
+      { factor: "pinned", value: "true" },
+    ];
+    expect(deriveDefaultCreateTimeFromFilters(filters, now)).toBeUndefined();
+  });
+
+  it("merges the displayTime date with the current local hh:mm:ss", () => {
+    const filters: MemoFilter[] = [{ factor: "displayTime", value: "2025-05-01" }];
+    const result = deriveDefaultCreateTimeFromFilters(filters, now);
+    expect(result).toBeDefined();
+    expect(result!.getFullYear()).toBe(2025);
+    expect(result!.getMonth()).toBe(4); // May (0-indexed)
+    expect(result!.getDate()).toBe(1);
+    expect(result!.getHours()).toBe(14);
+    expect(result!.getMinutes()).toBe(32);
+    expect(result!.getSeconds()).toBe(10);
+  });
+
+  it("ignores extra non-displayTime filters", () => {
+    const filters: MemoFilter[] = [
+      { factor: "tagSearch", value: "work" },
+      { factor: "displayTime", value: "2025-05-01" },
+      { factor: "pinned", value: "true" },
+    ];
+    const result = deriveDefaultCreateTimeFromFilters(filters, now);
+    expect(result?.getDate()).toBe(1);
+  });
+
+  it("returns undefined for a malformed YYYY-MM-DD value", () => {
+    const cases: MemoFilter[][] = [
+      [{ factor: "displayTime", value: "not-a-date" }],
+      [{ factor: "displayTime", value: "2025-13-40" }],
+      [{ factor: "displayTime", value: "" }],
+      [{ factor: "displayTime", value: "2025-5-1" }], // single-digit month/day
+    ];
+    for (const filters of cases) {
+      expect(deriveDefaultCreateTimeFromFilters(filters, now)).toBeUndefined();
+    }
+  });
+
+  it("uses real `new Date()` when `now` is omitted", () => {
+    const filters: MemoFilter[] = [{ factor: "displayTime", value: "2025-05-01" }];
+    const before = new Date();
+    const result = deriveDefaultCreateTimeFromFilters(filters);
+    const after = new Date();
+    expect(result).toBeDefined();
+    // Date components must come from the filter, not from `now` — guards
+    // against an impl that silently returns `new Date()` and ignores filters.
+    expect(result!.getFullYear()).toBe(2025);
+    expect(result!.getMonth()).toBe(4); // May (0-indexed)
+    expect(result!.getDate()).toBe(1);
+    // Time-of-day should fall between before and after (within 1s tolerance).
+    const resultTimeOnly = result!.getHours() * 3600 + result!.getMinutes() * 60 + result!.getSeconds();
+    const beforeTimeOnly = before.getHours() * 3600 + before.getMinutes() * 60 + before.getSeconds();
+    const afterTimeOnly = after.getHours() * 3600 + after.getMinutes() * 60 + after.getSeconds();
+    // Handle midnight rollover by allowing any value if before > after.
+    if (beforeTimeOnly <= afterTimeOnly) {
+      expect(resultTimeOnly).toBeGreaterThanOrEqual(beforeTimeOnly);
+      expect(resultTimeOnly).toBeLessThanOrEqual(afterTimeOnly);
+    }
+  });
+});