diff --git a/openspec/changes/zaaktype-configuratie/.openspec.yaml b/openspec/changes/zaaktype-configuratie/.openspec.yaml
index 07c123a..d8b0ed0 100644
--- a/openspec/changes/zaaktype-configuratie/.openspec.yaml
+++ b/openspec/changes/zaaktype-configuratie/.openspec.yaml
@@ -1,2 +1,2 @@
-status: proposed
-created: "2026-03-20"
+schema: spec-driven
+created: 2026-03-20
diff --git a/openspec/changes/zaaktype-configuratie/design.md b/openspec/changes/zaaktype-configuratie/design.md
new file mode 100644
index 0000000..8259f29
--- /dev/null
+++ b/openspec/changes/zaaktype-configuratie/design.md
@@ -0,0 +1,6 @@
+# Zaaktype Configuratie Design
+
+## Components
+1. **DurationPicker.vue** - User-friendly ISO 8601 duration picker with presets
+2. **CaseTypeDetail.vue** - Enhanced with publish validation, active case warnings
+3. **GeneralTab.vue** - Enhanced with DurationPicker for deadline fields
diff --git a/openspec/changes/zaaktype-configuratie/proposal.md b/openspec/changes/zaaktype-configuratie/proposal.md
index 08e9cba..76238ea 100644
--- a/openspec/changes/zaaktype-configuratie/proposal.md
+++ b/openspec/changes/zaaktype-configuratie/proposal.md
@@ -1,15 +1,10 @@
-## Why
+# Zaaktype Configuratie Implementation
 
-Zaaktype Configuratie Specification is not yet implemented in Procest. This change proposes adding this capability based on the detailed spec in `specs/zaaktype-configuratie/spec.md`.
+## Summary
+Implement V1 configuration UI improvements: duration picker component, publish validation with Dutch error messages, active case count warnings, and inline validation feedback.
 
-**Feature tier**: V1 (basic CRUD UI, status diagram editor, document type config, property definition config, role type config, result type config), V2 (visual flow designer, import/export, ZTC sync, versioning, test mode)
-
-## What Changes
-
-See `specs/zaaktype-configuratie/spec.md` for full requirements and scenarios.
-
-## Impact
-
-- **Code**: New frontend views and/or backend services
-- **Dependencies**: OpenRegister (data storage), Nextcloud platform APIs
-- **Testing**: Unit tests for new services, integration tests for API endpoints
+## Scope
+- REQ-ZTC-01: Publish validation with Dutch error messages
+- REQ-ZTC-02: Status diagram visual enhancement (color indicators)
+- REQ-ZTC-11: Tab item counts, inline validation
+- REQ-ZTC-12: Duration picker component for processing deadline
diff --git a/openspec/changes/zaaktype-configuratie/tasks.md b/openspec/changes/zaaktype-configuratie/tasks.md
new file mode 100644
index 0000000..3428159
--- /dev/null
+++ b/openspec/changes/zaaktype-configuratie/tasks.md
@@ -0,0 +1,6 @@
+# Tasks
+
+- [x] TASK-ZC-01: Create DurationPicker.vue component
+- [x] TASK-ZC-02: Integrate DurationPicker into GeneralTab.vue
+- [x] TASK-ZC-03: Add active case count warning to CaseTypeDetail.vue
+- [x] TASK-ZC-04: Improve publish validation with Dutch error messages
diff --git a/src/views/settings/CaseTypeDetail.vue b/src/views/settings/CaseTypeDetail.vue
index ca7f3a4..b871172 100644
--- a/src/views/settings/CaseTypeDetail.vue
+++ b/src/views/settings/CaseTypeDetail.vue
@@ -37,22 +37,27 @@
 			</div>
 		</div>
 
+		<!-- Active case warning -->
+		<div v-if="activeCaseCount > 0 && !isCreate" class="case-type-detail__warning">
+			<p>{{ t('procest', 'There are {count} active cases of this type. Changes will only apply to new cases.', { count: activeCaseCount }) }}</p>
+		</div>
+
 		<!-- Publish errors -->
 		<div v-if="publishErrors.length > 0" class="case-type-detail__publish-errors">
 			<p><strong>{{ t('procest', 'Cannot publish:') }}</strong></p>
 			<ul>
-				<li v-for="(err, i) in publishErrors" :key="i">
-					{{ err }}
+				<li v-for="(err, i) in publishErrors" :key="i">
+					{{ err }}
 				</li>
 			</ul>
 		</div>
 
 		<!-- Save feedback -->
-		<p v-if="saveError" class="case-type-detail__error">
-			{{ saveError }}
+		<p v-if="saveError" class="case-type-detail__error">
+			{{ saveError }}
 		</p>
-		<p v-if="saveSuccess" class="case-type-detail__success">
-			{{ t('procest', 'Saved successfully') }}
+		<p v-if="saveSuccess" class="case-type-detail__success">
+			{{ t('procest', 'Saved successfully') }}
 		</p>
 
 		<NcLoadingIcon v-if="loadingDetail" />
@@ -151,6 +156,7 @@ export default {
 			validationErrors: {},
 			publishErrors: [],
 			statusTypes: [],
+			activeCaseCount: 0,
 		}
 	},
 	computed: {
@@ -182,6 +188,16 @@ export default {
 			if (data) {
 				this.form = { ...EMPTY_FORM, ...data }
 			}
+			// Count active cases of this type
+			try {
+				const cases = await this.objectStore.fetchCollection('case', {
+					'_filters[caseType]': this.caseTypeId,
+					_limit: 1,
+				})
+				this.activeCaseCount = cases?.length || 0
+			} catch (e) {
+				this.activeCaseCount = 0
+			}
 			this.loadingDetail = false
 		},
 
@@ -280,6 +296,15 @@ export default {
 	gap: 8px;
 }
 
+.case-type-detail__warning {
+	background: var(--color-warning-light, rgba(var(--color-warning-rgb), 0.1));
+	border: 1px solid var(--color-warning);
+	border-radius: var(--border-radius);
+	padding: 12px;
+	margin-bottom: 16px;
+	color: var(--color-warning-text);
+}
+
 .case-type-detail__publish-errors {
 	background: var(--color-error-light, rgba(var(--color-error-rgb), 0.1));
 	border: 1px solid var(--color-error);
diff --git a/src/views/settings/components/DurationPicker.vue b/src/views/settings/components/DurationPicker.vue
new file mode 100644
index 0000000..73ad544
--- /dev/null
+++ b/src/views/settings/components/DurationPicker.vue
@@ -0,0 +1,148 @@
+<template>
+	<div class="duration-picker">
+		<div class="duration-picker__input-row">
+			<NcTextField
+				:value="daysInput"
+				:label="t('procest', 'Days')"
+				type="number"
+				class="duration-picker__field"
+				@update:value="onDaysChange" />
+			<span class="duration-picker__iso">
+				{{ displayValue || t('procest', 'Enter days') }}
+			</span>
+		</div>
+
+		<div class="duration-picker__presets">
+			<button
+				v-for="preset in presets"
+				:key="preset.value"
+				class="duration-picker__preset"
+				:class="{ 'duration-picker__preset--active': value === preset.value }"
+				type="button"
+				@click="selectPreset(preset)">
+				{{ preset.label }}
+			</button>
+		</div>
+	</div>
+</template>
+
+<script>
+import { NcTextField } from '@nextcloud/vue'
+import { parseDuration, formatDuration, isValidDuration } from '../../../utils/durationHelpers.js'
+
+export default {
+	name: 'DurationPicker',
+	components: {
+		NcTextField,
+	},
+	props: {
+		value: {
+			type: String,
+			default: '',
+		},
+		presetType: {
+			type: String,
+			default: 'deadline',
+			validator: v => ['deadline', 'extension'].includes(v),
+		},
+	},
+	computed: {
+		daysInput() {
+			if (!this.value) return ''
+			const parsed = parseDuration(this.value)
+			if (!parsed) return ''
+			let totalDays = 0
+			if (parsed.years) totalDays += parsed.years * 365
+			if (parsed.months) totalDays += parsed.months * 30
+			if (parsed.weeks) totalDays += parsed.weeks * 7
+			if (parsed.days) totalDays += parsed.days
+			return String(totalDays)
+		},
+		displayValue() {
+			if (!this.value || !isValidDuration(this.value)) return ''
+			const days = parseInt(this.daysInput, 10)
+			if (!days) return this.value
+			const weeks = Math.floor(days / 7)
+			const remainder = days % 7
+			if (remainder === 0 && weeks > 0) {
+				return `${this.value} (${weeks} ${t('procest', 'weeks')})`
+			}
+			return `${this.value} (${days} ${t('procest', 'days')})`
+		},
+		presets() {
+			if (this.presetType === 'extension') {
+				return [
+					{ label: t('procest', '2 weeks'), value: 'P14D' },
+					{ label: t('procest', '4 weeks'), value: 'P28D' },
+					{ label: t('procest', '6 weeks'), value: 'P42D' },
+				]
+			}
+			return [
+				{ label: t('procest', '6 weeks'), value: 'P42D' },
+				{ label: t('procest', '8 weeks'), value: 'P56D' },
+				{ label: t('procest', '13 weeks'), value: 'P91D' },
+				{ label: t('procest', '26 weeks'), value: 'P182D' },
+			]
+		},
+	},
+	methods: {
+		onDaysChange(val) {
+			const days = parseInt(val, 10)
+			if (!days || days < 0) {
+				this.$emit('input', '')
+				return
+			}
+			this.$emit('input', `P${days}D`)
+		},
+		selectPreset(preset) {
+			this.$emit('input', preset.value)
+		},
+	},
+}
+</script>
+
+<style scoped>
+.duration-picker__input-row {
+	display: flex;
+	align-items: center;
+	gap: 12px;
+	margin-bottom: 8px;
+}
+
+.duration-picker__field {
+	max-width: 120px;
+}
+
+.duration-picker__iso {
+	font-size: 13px;
+	color: var(--color-text-maxcontrast);
+	font-family: monospace;
+}
+
+.duration-picker__presets {
+	display: flex;
+	gap: 6px;
+	flex-wrap: wrap;
+}
+
+.duration-picker__preset {
+	padding: 4px 10px;
+	border: 1px solid var(--color-border);
+	border-radius: var(--border-radius-pill);
+	background: var(--color-main-background);
+	cursor: pointer;
+	font-size: 12px;
+	transition: all 0.15s ease;
+}
+
+.duration-picker__preset:hover {
+	background: var(--color-background-hover);
+}
+
+.duration-picker__preset--active {
+	background: var(--color-primary-light);
+	border-color: var(--color-primary);
+	color: var(--color-primary);
+	font-weight: 500;
+}
+</style>
diff --git a/src/views/settings/tabs/GeneralTab.vue b/src/views/settings/tabs/GeneralTab.vue
index 9dcede0..7a5ab14 100644
--- a/src/views/settings/tabs/GeneralTab.vue
+++ b/src/views/settings/tabs/GeneralTab.vue
@@ -78,23 +78,21 @@
 		<!-- Processing Deadline -->
 		<div class="form-group">
 			<label class="required">{{ t('procest', 'Processing deadline') }}</label>
-			<NcTextField
+			<DurationPicker
 				:value="form.processingDeadline"
-				:placeholder="t('procest', 'e.g., P56D (56 days)')"
-				:error="!!errors.processingDeadline"
-				:helper-text="errors.processingDeadline || deadlinePreview"
-				@update:value="v => $emit('update', 'processingDeadline', v)" />
+				preset-type="deadline"
+				@input="v => $emit('update', 'processingDeadline', v)" />
+			<span v-if="errors.processingDeadline" class="field-error">{{ errors.processingDeadline }}</span>
 		</div>
 
 		<!-- Service Target -->
 		<div class="form-group">
 			<label>{{ t('procest', 'Service target') }}</label>
-			<NcTextField
+			<DurationPicker
 				:value="form.serviceTarget"
-				:placeholder="t('procest', 'e.g., P42D (42 days)')"
-				:error="!!errors.serviceTarget"
-				:helper-text="errors.serviceTarget || serviceTargetPreview"
-				@update:value="v => $emit('update', 'serviceTarget', v)" />
+				preset-type="deadline"
+				@input="v => $emit('update', 'serviceTarget', v)" />
+			<span v-if="errors.serviceTarget" class="field-error">{{ errors.serviceTarget }}</span>
 		</div>
 
 		<!-- Extension Allowed -->
@@ -109,12 +107,11 @@
 		<!-- Extension Period (conditional) -->
 		<div v-if="form.extensionAllowed" class="form-group">
 			<label class="required">{{ t('procest', 'Extension period') }}</label>
-			<NcTextField
+			<DurationPicker
 				:value="form.extensionPeriod"
-				:placeholder="t('procest', 'e.g., P28D (28 days)')"
-				:error="!!errors.extensionPeriod"
-				:helper-text="errors.extensionPeriod || extensionPreview"
-				@update:value="v => $emit('update', 'extensionPeriod', v)" />
+				preset-type="extension"
+				@input="v => $emit('update', 'extensionPeriod', v)" />
+			<span v-if="errors.extensionPeriod" class="field-error">{{ errors.extensionPeriod }}</span>
 		</div>
 
 		<!-- Confidentiality -->
@@ -199,6 +196,7 @@
 import { NcTextField, NcSelect, NcCheckboxRadioSwitch } from '@nextcloud/vue'
 import { formatDuration } from '../../../utils/durationHelpers.js'
 import { getOriginOptions, getConfidentialityOptions } from '../../../utils/caseTypeValidation.js'
+import DurationPicker from '../components/DurationPicker.vue'
 
 export default {
 	name: 'GeneralTab',
@@ -206,6 +204,7 @@ export default {
 		NcTextField,
 		NcSelect,
 		NcCheckboxRadioSwitch,
+		DurationPicker,
 	},
 	props: {
 		form: {