diff --git a/internal/handler/entry_handler.go b/internal/handler/entry_handler.go
index f414a19..92703a2 100644
--- a/internal/handler/entry_handler.go
+++ b/internal/handler/entry_handler.go
@@ -19,12 +19,47 @@ func NewEntryHandler(svc *service.EntryService) *EntryHandler {
 
 func (h *EntryHandler) Routes(r chi.Router) {
 	r.Post("/entries/start", h.Start)
+	r.Post("/entries", h.CreateInterval)
 	r.Post("/entries/{id}/stop", h.StopByID)
 	r.Get("/entries", h.List)
 	r.Put("/entries/{id}", h.Update)
 	r.Delete("/entries/{id}", h.Delete)
 }
 
+// CreateInterval POST /api/entries  — create a completed interval with explicit times
+func (h *EntryHandler) CreateInterval(w http.ResponseWriter, r *http.Request) {
+	var body struct {
+		StartTime int64  `json:"start_time"`
+		EndTime   int64  `json:"end_time"`
+		Note      string `json:"note"`
+	}
+	if err := decodeJSON(r, &body); err != nil {
+		writeError(w, http.StatusBadRequest, "invalid JSON")
+		return
+	}
+	if body.StartTime == 0 || body.EndTime == 0 {
+		writeError(w, http.StatusBadRequest, "start_time and end_time are required")
+		return
+	}
+	entry, err := h.svc.CreateInterval(r.Context(), service.CreateIntervalInput{
+		StartTime: body.StartTime,
+		EndTime:   body.EndTime,
+		Note:      body.Note,
+	})
+	if err != nil {
+		switch {
+		case errors.Is(err, service.ErrCrossesMidnight):
+			writeError(w, http.StatusUnprocessableEntity, err.Error())
+		case errors.Is(err, service.ErrDayAlreadyClosed):
+			writeError(w, http.StatusConflict, err.Error())
+		default:
+			writeError(w, http.StatusInternalServerError, err.Error())
+		}
+		return
+	}
+	writeJSON(w, http.StatusCreated, entry)
+}
+
 // Start POST /api/entries/start
 func (h *EntryHandler) Start(w http.ResponseWriter, r *http.Request) {
 	var body struct {
diff --git a/internal/service/entry_service.go b/internal/service/entry_service.go
index 322e155..76e0dfd 100644
--- a/internal/service/entry_service.go
+++ b/internal/service/entry_service.go
@@ -176,6 +176,15 @@ func (s *EntryService) Update(ctx context.Context, id string, input UpdateEntryI
 		return nil, err
 	}
 
+	// Disallow editing entries that belong to a closed day.
+	closed, err := s.closedDays.GetByDayKey(ctx, e.DayKey)
+	if err != nil && !errors.Is(err, sql.ErrNoRows) {
+		return nil, err
+	}
+	if closed != nil {
+		return nil, ErrDayAlreadyClosed
+	}
+
 	if input.StartTime != nil {
 		e.StartTime = *input.StartTime
 		e.DayKey = s.dayKeyForMs(e.StartTime)
@@ -203,6 +212,50 @@ func (s *EntryService) Update(ctx context.Context, id string, input UpdateEntryI
 	return e, nil
 }
 
+// CreateIntervalInput holds fields for a manually created completed interval.
+type CreateIntervalInput struct {
+	StartTime int64
+	EndTime   int64
+	Note      string
+}
+
+// CreateInterval adds a completed interval with explicit start and end times.
+// Rules: same-day, end > start, day not closed, no currently running entry on that day (check running globally).
+func (s *EntryService) CreateInterval(ctx context.Context, input CreateIntervalInput) (*domain.Entry, error) {
+	if input.EndTime <= input.StartTime {
+		return nil, fmt.Errorf("end_time must be after start_time")
+	}
+
+	startDayKey := s.dayKeyForMs(input.StartTime)
+	endDayKey := s.dayKeyForMs(input.EndTime)
+	if startDayKey != endDayKey {
+		return nil, ErrCrossesMidnight
+	}
+
+	// Check day is not closed.
+	closed, err := s.closedDays.GetByDayKey(ctx, startDayKey)
+	if err != nil && !errors.Is(err, sql.ErrNoRows) {
+		return nil, err
+	}
+	if closed != nil {
+		return nil, ErrDayAlreadyClosed
+	}
+
+	nowMs := s.nowMs()
+	e := &domain.Entry{
+		ID:        uuid.New().String(),
+		StartTime: input.StartTime,
+		EndTime:   &input.EndTime,
+		Note:      input.Note,
+		DayKey:    startDayKey,
+		UpdatedAt: nowMs,
+	}
+	if err := s.entries.Create(ctx, e); err != nil {
+		return nil, err
+	}
+	return e, nil
+}
+
 // Delete soft-deletes an entry.
 func (s *EntryService) Delete(ctx context.Context, id string) error {
 	nowMs := s.nowMs()
diff --git a/internal/service/entry_service_test.go b/internal/service/entry_service_test.go
index 1a07cda..34f8371 100644
--- a/internal/service/entry_service_test.go
+++ b/internal/service/entry_service_test.go
@@ -2,6 +2,7 @@ package service_test
 
 import (
 	"context"
+	"errors"
 	"testing"
 	"time"
 
@@ -134,3 +135,98 @@ func TestListEntries(t *testing.T) {
 		t.Fatalf("expected 3 entries, got %d", len(entries))
 	}
 }
+
+func TestCreateInterval(t *testing.T) {
+	ctx := context.Background()
+	svc := newTestServices(t)
+
+	now := time.Now().UTC()
+	startMs := now.Add(-2 * time.Hour).UnixMilli()
+	endMs := now.Add(-1 * time.Hour).UnixMilli()
+
+	entry, err := svc.CreateInterval(ctx, service.CreateIntervalInput{
+		StartTime: startMs,
+		EndTime:   endMs,
+		Note:      "manual entry",
+	})
+	if err != nil {
+		t.Fatalf("CreateInterval: %v", err)
+	}
+	if entry.EndTime == nil {
+		t.Fatal("expected EndTime to be set")
+	}
+	if *entry.EndTime != endMs {
+		t.Errorf("expected EndTime %d, got %d", endMs, *entry.EndTime)
+	}
+	if entry.Note != "manual entry" {
+		t.Errorf("expected note 'manual entry', got %q", entry.Note)
+	}
+}
+
+func TestCreateIntervalEndBeforeStart(t *testing.T) {
+	ctx := context.Background()
+	svc := newTestServices(t)
+
+	now := time.Now().UTC().UnixMilli()
+	_, err := svc.CreateInterval(ctx, service.CreateIntervalInput{
+		StartTime: now,
+		EndTime:   now - 1000,
+	})
+	if err == nil {
+		t.Fatal("expected error for end_time before start_time")
+	}
+}
+
+func TestCreateIntervalCrossesMidnight(t *testing.T) {
+	ctx := context.Background()
+	svc := newTestServices(t)
+
+	yesterday := time.Now().UTC().Add(-24 * time.Hour)
+	startMs := time.Date(yesterday.Year(), yesterday.Month(), yesterday.Day(), 23, 0, 0, 0, time.UTC).UnixMilli()
+	endMs := time.Now().UTC().Add(time.Hour).UnixMilli()
+
+	_, err := svc.CreateInterval(ctx, service.CreateIntervalInput{
+		StartTime: startMs,
+		EndTime:   endMs,
+	})
+	if err == nil {
+		t.Fatal("expected ErrCrossesMidnight")
+	}
+	if !errors.Is(err, service.ErrCrossesMidnight) {
+		t.Fatalf("expected ErrCrossesMidnight, got %v", err)
+	}
+}
+
+func TestUpdateRejectsClosedDay(t *testing.T) {
+	ctx := context.Background()
+
+	db, err := store.Open(":memory:")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	entryStore := store.NewEntryStore(db)
+	closedDayStore := store.NewClosedDayStore(db)
+	settingsStore := store.NewSettingsStore(db)
+	tz, _ := time.LoadLocation("UTC")
+	svc := service.NewEntryService(entryStore, closedDayStore, settingsStore, tz)
+	daySvc := service.NewDayService(entryStore, closedDayStore, settingsStore, tz)
+
+	entry, _ := svc.Start(ctx, "")
+	svc.Stop(ctx)
+
+	today := time.Now().UTC().Format("2006-01-02")
+	if _, err := daySvc.CloseDay(ctx, today); err != nil {
+		t.Fatalf("CloseDay: %v", err)
+	}
+
+	note := "should fail"
+	_, err = svc.Update(ctx, entry.ID, service.UpdateEntryInput{Note: &note})
+	if err == nil {
+		t.Fatal("expected error updating entry in closed day")
+	}
+	if !errors.Is(err, service.ErrDayAlreadyClosed) {
+		t.Fatalf("expected ErrDayAlreadyClosed, got %v", err)
+	}
+}
diff --git a/web/src/lib/api/client.ts b/web/src/lib/api/client.ts
index ca8d53a..7e9339b 100644
--- a/web/src/lib/api/client.ts
+++ b/web/src/lib/api/client.ts
@@ -85,6 +85,8 @@ export interface Settings {
 
 export const entries = {
 	start: (note = '') => request<Entry>('POST', '/entries/start', { note }),
+	createInterval: (startTime: number, endTime: number, note = '') =>
+		request<Entry>('POST', '/entries', { start_time: startTime, end_time: endTime, note }),
 	stop: (id: string) => request<Entry>('POST', `/entries/${id}/stop`),
 	list: (from?: string, to?: string) => {
 		const params = new URLSearchParams();
diff --git a/web/src/lib/utils.ts b/web/src/lib/utils.ts
index 600f51d..d091317 100644
--- a/web/src/lib/utils.ts
+++ b/web/src/lib/utils.ts
@@ -71,7 +71,21 @@ export function formatDelta(ms: number): string {
 	return `${sign}${formatDurationShort(Math.abs(ms))}`;
 }
 
-/** Workday bit mask: Mon=1, Tue=2, Wed=4, Thu=8, Fri=16, Sat=32, Sun=64 */
+/** Parse "HH:MM" time string on a given dayKey (YYYY-MM-DD) into unix ms (local time). */
+export function parseTimeInput(dayKey: string, hhmm: string): number | null {
+	if (!/^\d{2}:\d{2}$/.test(hhmm)) return null;
+	const [h, m] = hhmm.split(':').map(Number);
+	if (h > 23 || m > 59) return null;
+	const d = new Date(`${dayKey}T${hhmm}:00`);
+	return isNaN(d.getTime()) ? null : d.getTime();
+}
+
+/** Format unix ms as "HH:MM" in local time (for time inputs). */
+export function toTimeInput(ms: number): string {
+	const d = new Date(ms);
+	return `${pad(d.getHours())}:${pad(d.getMinutes())}`;
+}
+
 export const WEEKDAY_BITS = [1, 2, 4, 8, 16, 32, 64]; // Mon..Sun
 
 /** JS getDay() → our bit (Sun=0 in JS → bit 64) */
diff --git a/web/src/routes/today/+page.svelte b/web/src/routes/today/+page.svelte
index f7a0997..32c7d65 100644
--- a/web/src/routes/today/+page.svelte
+++ b/web/src/routes/today/+page.svelte
@@ -1,7 +1,7 @@
 <script lang="ts">
 	import { onMount, onDestroy } from 'svelte';
 	import { entries, days, type Entry, type ClosedDay, ApiError } from '$lib/api/client';
-	import { todayKey, formatTime, formatDuration, formatDurationShort } from '$lib/utils';
+	import { todayKey, formatTime, formatDuration, formatDurationShort, parseTimeInput, toTimeInput } from '$lib/utils';
 
 	let today = todayKey();
 	let entryList: Entry[] = $state([]);
@@ -12,6 +12,20 @@
 	let error = $state('');
 	let loading = $state(false);
 
+	// Add-interval form
+	let showAddForm = $state(false);
+	let addStart = $state('');
+	let addEnd = $state('');
+	let addNote = $state('');
+	let addError = $state('');
+
+	// Inline edit state
+	let editingId = $state<string | null>(null);
+	let editStart = $state('');
+	let editEnd = $state('');
+	let editNote = $state('');
+	let editError = $state('');
+
 	let timer: ReturnType<typeof setInterval> | null = null;
 
 	async function load() {
@@ -112,6 +126,84 @@
 		}
 	}
 
+	// ── Add interval ────────────────────────────────────────────────────────────
+
+	function openAddForm() {
+		addStart = '';
+		addEnd = '';
+		addNote = '';
+		addError = '';
+		showAddForm = true;
+	}
+
+	function closeAddForm() {
+		showAddForm = false;
+		addError = '';
+	}
+
+	async function handleAddInterval() {
+		addError = '';
+		const startMs = parseTimeInput(today, addStart);
+		const endMs = parseTimeInput(today, addEnd);
+		if (startMs === null) { addError = 'Invalid start time'; return; }
+		if (endMs === null) { addError = 'Invalid end time'; return; }
+		if (endMs <= startMs) { addError = 'End must be after start'; return; }
+		try {
+			const e = await entries.createInterval(startMs, endMs, addNote);
+			entryList = [...entryList, e].sort((a, b) => a.start_time - b.start_time);
+			closeAddForm();
+		} catch (e) {
+			addError = e instanceof ApiError ? e.message : String(e);
+		}
+	}
+
+	// ── Inline edit ─────────────────────────────────────────────────────────────
+
+	function startEdit(entry: Entry) {
+		editingId = entry.id;
+		editStart = toTimeInput(entry.start_time);
+		editEnd = entry.end_time ? toTimeInput(entry.end_time) : '';
+		editNote = entry.note;
+		editError = '';
+	}
+
+	function cancelEdit() {
+		editingId = null;
+		editError = '';
+	}
+
+	async function saveEdit(entry: Entry) {
+		editError = '';
+		const startMs = parseTimeInput(today, editStart);
+		if (startMs === null) { editError = 'Invalid start time'; return; }
+
+		// end_time: only required if the entry is not running
+		let endMs: number | undefined;
+		if (!entry.end_time && editEnd === '') {
+			// still running, no end — that's fine, don't send end_time
+		} else {
+			const parsed = parseTimeInput(today, editEnd);
+			if (parsed === null) { editError = 'Invalid end time'; return; }
+			if (parsed <= startMs) { editError = 'End must be after start'; return; }
+			endMs = parsed;
+		}
+
+		try {
+			const updated = await entries.update(entry.id, {
+				start_time: startMs,
+				...(endMs !== undefined ? { end_time: endMs } : {}),
+				note: editNote
+			});
+			entryList = entryList
+				.map((e) => (e.id === updated.id ? updated : e))
+				.sort((a, b) => a.start_time - b.start_time);
+			if (running?.id === updated.id) running = updated;
+			editingId = null;
+		} catch (e) {
+			editError = e instanceof ApiError ? e.message : String(e);
+		}
+	}
+
 	const totalWorkedMs = $derived(
 		entryList.reduce((sum, e) => {
 			if (e.end_time === null) return sum;
@@ -166,28 +258,78 @@
 
 	<!-- Entry list -->
 	<section class="entries">
-		<h2>Entries</h2>
+		<div class="entries-header">
+			<h2>Entries</h2>
+			{#if !closedDay}
+				<button class="btn-add" onclick={openAddForm} title="Add interval">+ Add interval</button>
+			{/if}
+		</div>
+
+		<!-- Add-interval form -->
+		{#if showAddForm}
+			<div class="interval-form">
+				<h3>Add interval</h3>
+				{#if addError}<p class="form-error">{addError}</p>{/if}
+				<div class="form-row">
+					<label>
+						Start
+						<input type="time" bind:value={addStart} required />
+					</label>
+					<label>
+						End
+						<input type="time" bind:value={addEnd} required />
+					</label>
+					<label class="note-label">
+						Note
+						<input type="text" bind:value={addNote} placeholder="Optional" />
+					</label>
+				</div>
+				<div class="form-actions">
+					<button class="btn save" onclick={handleAddInterval}>Save</button>
+					<button class="btn cancel" onclick={closeAddForm}>Cancel</button>
+				</div>
+			</div>
+		{/if}
+
 		{#if entryList.length === 0}
 			<p class="empty">No entries yet today.</p>
 		{:else}
 			{#each entryList as entry (entry.id)}
-				<div class="entry" class:running={entry.end_time === null}>
-					<span class="time">{formatTime(entry.start_time)}</span>
-					<span class="dash">→</span>
-					<span class="time">{entry.end_time ? formatTime(entry.end_time) : '…'}</span>
-					{#if entry.end_time}
-						<span class="dur">{formatDuration(entry.end_time - entry.start_time)}</span>
-					{/if}
-					{#if entry.note}
-						<span class="note">{entry.note}</span>
-					{/if}
-					{#if entry.auto_stopped}
-						<span class="badge auto">auto-stopped</span>
-					{/if}
-					{#if !closedDay}
-						<button class="del" onclick={() => handleDeleteEntry(entry.id)} title="Delete">✕</button>
-					{/if}
-				</div>
+				{#if editingId === entry.id}
+					<!-- Inline edit row -->
+					<div class="entry editing">
+						{#if editError}<p class="form-error">{editError}</p>{/if}
+						<div class="edit-row">
+							<input type="time" bind:value={editStart} class="time-input" />
+							<span class="dash">→</span>
+							<input type="time" bind:value={editEnd} class="time-input" placeholder="--:--" disabled={!entry.end_time && editEnd === ''} />
+							<input type="text" bind:value={editNote} class="note-input" placeholder="Note" />
+						</div>
+						<div class="edit-actions">
+							<button class="btn save sm" onclick={() => saveEdit(entry)}>Save</button>
+							<button class="btn cancel sm" onclick={cancelEdit}>Cancel</button>
+						</div>
+					</div>
+				{:else}
+					<div class="entry" class:running={entry.end_time === null}>
+						<span class="time">{formatTime(entry.start_time)}</span>
+						<span class="dash">→</span>
+						<span class="time">{entry.end_time ? formatTime(entry.end_time) : '…'}</span>
+						{#if entry.end_time}
+							<span class="dur">{formatDuration(entry.end_time - entry.start_time)}</span>
+						{/if}
+						{#if entry.note}
+							<span class="note">{entry.note}</span>
+						{/if}
+						{#if entry.auto_stopped}
+							<span class="badge auto">auto-stopped</span>
+						{/if}
+						{#if !closedDay}
+							<button class="edit-btn" onclick={() => startEdit(entry)} title="Edit">✎</button>
+							<button class="del" onclick={() => handleDeleteEntry(entry.id)} title="Delete">✕</button>
+						{/if}
+					</div>
+				{/if}
 			{/each}
 			<div class="total">Total: {formatDurationShort(totalWorkedMs)}</div>
 		{/if}
@@ -196,7 +338,8 @@
 
 <style>
 	h1 { margin: 0 0 1rem; font-size: 1.4rem; }
-	h2 { font-size: 1rem; margin: 1.5rem 0 0.5rem; color: #495057; }
+	h2 { font-size: 1rem; margin: 0; color: #495057; }
+	h3 { margin: 0 0 0.75rem; font-size: 0.95rem; color: #343a40; }
 	.error { color: #c0392b; background: #fde8e4; padding: 0.5rem; border-radius: 6px; }
 	.closed-banner { display: flex; align-items: center; justify-content: space-between;
 		padding: 0.75rem 1rem; border-radius: 8px; margin-bottom: 1rem; font-weight: 500; }
@@ -210,24 +353,49 @@
 	.timer.idle { color: #6c757d; }
 	.start-row { display: flex; gap: 0.5rem; justify-content: center; margin-top: 1rem; }
 	.start-row input { padding: 0.5rem 0.75rem; border: 1px solid #ced4da; border-radius: 6px; font-size: 0.95rem; width: 220px; }
-	.btn { padding: 0.55rem 1.4rem; border: none; border-radius: 6px; font-size: 1rem; font-weight: 600; transition: opacity 0.15s; }
+	.btn { padding: 0.55rem 1.4rem; border: none; border-radius: 6px; font-size: 1rem; font-weight: 600; transition: opacity 0.15s; cursor: pointer; }
 	.btn:hover { opacity: 0.88; }
 	.btn.start { background: #2c7be5; color: #fff; margin-top: 1rem; }
 	.btn.stop { background: #e74c3c; color: #fff; margin-top: 1rem; }
 	.btn.close-day { background: #343a40; color: #fff; margin-top: 1rem; display: block; }
+	.btn.save { background: #2c7be5; color: #fff; }
+	.btn.cancel { background: #e9ecef; color: #343a40; }
+	.btn.sm { padding: 0.3rem 0.8rem; font-size: 0.875rem; }
 	.quick-mark { display: flex; gap: 0.5rem; align-items: center; margin-top: 1rem; flex-wrap: wrap; }
 	.quick-mark span { color: #6c757d; font-size: 0.875rem; }
-	.quick-mark button { padding: 0.35rem 0.75rem; border: 1px solid #ced4da; background: #fff; border-radius: 6px; font-size: 0.875rem; }
+	.quick-mark button { padding: 0.35rem 0.75rem; border: 1px solid #ced4da; background: #fff; border-radius: 6px; font-size: 0.875rem; cursor: pointer; }
 	.quick-mark button:hover { background: #e9ecef; }
-	.entries { border-top: 1px solid #dee2e6; margin-top: 1.5rem; padding-top: 0.5rem; }
+	.entries { border-top: 1px solid #dee2e6; margin-top: 1.5rem; padding-top: 0.75rem; }
+	.entries-header { display: flex; align-items: center; justify-content: space-between; margin-bottom: 0.5rem; }
+	.btn-add { background: none; border: 1px solid #2c7be5; color: #2c7be5; border-radius: 6px;
+		padding: 0.25rem 0.75rem; font-size: 0.85rem; font-weight: 600; cursor: pointer; }
+	.btn-add:hover { background: #eaf3ff; }
+	/* Add-interval form */
+	.interval-form { background: #f8f9fa; border: 1px solid #dee2e6; border-radius: 8px;
+		padding: 1rem; margin-bottom: 1rem; }
+	.form-row { display: flex; gap: 1rem; flex-wrap: wrap; align-items: flex-end; }
+	.form-row label { display: flex; flex-direction: column; gap: 0.25rem; font-size: 0.85rem; color: #495057; }
+	.form-row input[type="time"], .form-row input[type="text"] {
+		padding: 0.4rem 0.6rem; border: 1px solid #ced4da; border-radius: 6px; font-size: 0.9rem; }
+	.note-label { flex: 1; min-width: 160px; }
+	.form-actions { display: flex; gap: 0.5rem; margin-top: 0.75rem; }
+	.form-error { color: #c0392b; font-size: 0.85rem; margin: 0 0 0.5rem; }
+	/* Entry rows */
 	.entry { display: flex; align-items: center; gap: 0.5rem; padding: 0.5rem 0; border-bottom: 1px solid #f1f3f5; font-size: 0.9rem; }
 	.entry.running { background: #eaf3ff; border-radius: 6px; padding: 0.5rem 0.5rem; }
+	.entry.editing { display: block; background: #f8f9fa; border: 1px solid #dee2e6; border-radius: 6px; padding: 0.6rem 0.75rem; margin-bottom: 0.25rem; }
+	.edit-row { display: flex; align-items: center; gap: 0.5rem; flex-wrap: wrap; }
+	.time-input { width: 90px; padding: 0.3rem 0.4rem; border: 1px solid #ced4da; border-radius: 5px; font-size: 0.9rem; font-variant-numeric: tabular-nums; }
+	.note-input { flex: 1; min-width: 120px; padding: 0.3rem 0.5rem; border: 1px solid #ced4da; border-radius: 5px; font-size: 0.9rem; }
+	.edit-actions { display: flex; gap: 0.5rem; margin-top: 0.5rem; }
 	.time { font-variant-numeric: tabular-nums; color: #343a40; }
 	.dash { color: #adb5bd; }
 	.dur { font-variant-numeric: tabular-nums; color: #6c757d; margin-left: auto; }
 	.note { color: #495057; font-style: italic; }
 	.badge.auto { font-size: 0.75rem; background: #fff3cd; color: #856404; padding: 0.1rem 0.4rem; border-radius: 4px; }
-	.del { margin-left: 0.5rem; background: none; border: none; color: #adb5bd; font-size: 1rem; padding: 0 0.25rem; }
+	.edit-btn { margin-left: auto; background: none; border: none; color: #adb5bd; font-size: 1rem; padding: 0 0.25rem; cursor: pointer; }
+	.edit-btn:hover { color: #2c7be5; }
+	.del { background: none; border: none; color: #adb5bd; font-size: 1rem; padding: 0 0.25rem; cursor: pointer; }
 	.del:hover { color: #e74c3c; }
 	.total { text-align: right; padding: 0.5rem 0; color: #495057; font-weight: 600; }
 	.empty { color: #6c757d; font-style: italic; }