diff --git a/docs/BUG_HISTORY.md b/docs/BUG_HISTORY.md
index bdf890a1..df271f96 100644
--- a/docs/BUG_HISTORY.md
+++ b/docs/BUG_HISTORY.md
@@ -5339,3 +5339,19 @@
 - 复发自：无
 - 修复版本：97620634
 
+## BUG-353 | 不确定时间只扫五档时段，补充描述里的钟点纠正用不上
+
+- 状态：resolved
+- 首次发现：2026-08-22
+- 最近更新：2026-08-22
+- 影响面：出生时间表单、`profiles.declared_window_start/end`、V9 Case 候选窗、普通咨询 declared window、账户 PATCH
+- 用户现象：用户已把不确定时间改成 14:30–15:00，或写在补充描述里，生时纠正和 Agent 仍按下午 12:00–17:59 扫描。
+- 触发条件：`birth_time_source=period_only` 且用户记得的是一段钟点而不是五档粗时段；旧资料把钟点写在 `birth_time_clue`。
+- 根因：`period_only` 只把 `birth_time_period` 映射成五档固定窗。`birth_time_clue` 不进 Case fingerprint、不进 `candidate_range`、也不被解析。Case 窗在创建时冻结，聊天工具不能改。正则解析备注会把“6—8 点”这类歧义话当成扫描分钟。
+- 修复：不确定路径改为开始/结束钟点，不再收集备注。保存 `declared_window_start/end`；自定义钟点优先于五档时段；开始结束相同则拒绝；允许跨午夜。旧 `afternoon` 等行回填对应钟点，用户可以收紧到 14:30–15:00。收紧后 fingerprint 变化，首页开新 Case。不解析 clue，保存时把 clue 写成 null。
+- 验证：`frontend/tests/birth-time-intake.test.ts` 锁定开始结束表单、14:30–15:00 持久化且不留下 afternoon 桶；`frontend/tests/declared-birth-window.test.ts` 锁定自定义钟点覆盖 afternoon；`frontend/tests/rectification-v9-case-service.test.ts` 锁定 Case 开窗 14:30–15:00 且 fingerprint 变化；`frontend/tests/consultation-route-service.test.ts` 锁定咨询窗；`frontend/tests/account-api.test.ts` 锁定 PATCH 接受开始结束、拒绝同一分钟。
+- 防复发：不得把备注正则解析成扫描窗。不得只扫五档时段而丢掉用户选择的开始结束。不得把自定义窗的中点写成 `reported_birth_time`。改窗必须开新 Case，旧会话继续展示冻结窗。
+- 相关记录：BUG-197、BUG-198
+- 复发自：BUG-197（不确定入口恢复后仍用五档时段加备注，备注从未进入扫描窗）
+- 修复版本：待提交
+
diff --git a/frontend/src/app/api/account/route.ts b/frontend/src/app/api/account/route.ts
index bbe86bdc..65408dfa 100644
--- a/frontend/src/app/api/account/route.ts
+++ b/frontend/src/app/api/account/route.ts
@@ -49,26 +49,43 @@ export async function GET() {
     const admin = createAdminSupabaseClient();
     let { data: profile, error: profileError } = await supabase
       .from("profiles")
-      .select("credits,active_birth_time,birth_time_status,birth_date,reported_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source,name,birth_time,rectification_case_id")
+      .select("credits,active_birth_time,birth_time_status,birth_date,reported_birth_time,birth_time_source,birth_time_period,declared_window_start,declared_window_end,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source,name,birth_time,rectification_case_id")
       .eq("id", userId)
       .single();
 
     if (profileError && isMissingProfileColumn(profileError)) {
-      const fallback = await supabase
+      const withoutDeclaredWindow = await supabase
         .from("profiles")
-        .select("credits,active_birth_time,birth_time_status,birth_date,reported_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,name,birth_time,rectification_case_id")
+        .select("credits,active_birth_time,birth_time_status,birth_date,reported_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source,name,birth_time,rectification_case_id")
         .eq("id", userId)
         .single();
-      profile = fallback.data ? {
-        ...fallback.data,
-        birth_place_label: undefined,
-        birth_place_type: undefined,
-        birth_place_provider: undefined,
-        birth_place_provider_id: undefined,
-        timezone_id: undefined,
-        timezone_source: undefined,
-      } : null;
-      profileError = fallback.error;
+      if (!withoutDeclaredWindow.error && withoutDeclaredWindow.data) {
+        profile = {
+          ...withoutDeclaredWindow.data,
+          declared_window_start: undefined,
+          declared_window_end: undefined,
+        };
+        profileError = withoutDeclaredWindow.error;
+      } else if (withoutDeclaredWindow.error && isMissingProfileColumn(withoutDeclaredWindow.error)) {
+        const fallback = await supabase
+          .from("profiles")
+          .select("credits,active_birth_time,birth_time_status,birth_date,reported_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,name,birth_time,rectification_case_id")
+          .eq("id", userId)
+          .single();
+        profile = fallback.data ? {
+          ...fallback.data,
+          birth_place_label: undefined,
+          birth_place_type: undefined,
+          birth_place_provider: undefined,
+          birth_place_provider_id: undefined,
+          timezone_id: undefined,
+          timezone_source: undefined,
+        } : null;
+        profileError = fallback.error;
+      } else {
+        profile = withoutDeclaredWindow.data;
+        profileError = withoutDeclaredWindow.error;
+      }
     }
 
     if (profileError || !profile) {
@@ -170,28 +187,45 @@ export async function PATCH(request: Request) {
     const admin = createAdminSupabaseClient();
     let { data: currentProfile, error: currentProfileError } = await admin
       .from("profiles")
-      .select("birth_date,birth_time,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,birth_time_status,rectification_case_id,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source")
+      .select("birth_date,birth_time,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,declared_window_start,declared_window_end,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,birth_time_status,rectification_case_id,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source")
       .eq("id", userId)
       .maybeSingle();
     if (currentProfileError && isMissingProfileColumn(currentProfileError)) {
-      const fallback = await admin
+      const withoutDeclaredWindow = await admin
         .from("profiles")
-        .select("birth_date,birth_time,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,birth_time_status,rectification_case_id,country_code,province_code,city_code,district_code")
+        .select("birth_date,birth_time,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,birth_time_status,rectification_case_id,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source")
         .eq("id", userId)
         .maybeSingle();
-      currentProfile = fallback.data ? {
-        ...fallback.data,
-        latitude: undefined,
-        longitude: undefined,
-        timezone_offset: undefined,
-        birth_place_label: undefined,
-        birth_place_type: undefined,
-        birth_place_provider: undefined,
-        birth_place_provider_id: undefined,
-        timezone_id: undefined,
-        timezone_source: undefined,
-      } : null;
-      currentProfileError = fallback.error;
+      if (!withoutDeclaredWindow.error && withoutDeclaredWindow.data) {
+        currentProfile = {
+          ...withoutDeclaredWindow.data,
+          declared_window_start: undefined,
+          declared_window_end: undefined,
+        };
+        currentProfileError = withoutDeclaredWindow.error;
+      } else if (withoutDeclaredWindow.error && isMissingProfileColumn(withoutDeclaredWindow.error)) {
+        const fallback = await admin
+          .from("profiles")
+          .select("birth_date,birth_time,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,birth_time_status,rectification_case_id,country_code,province_code,city_code,district_code")
+          .eq("id", userId)
+          .maybeSingle();
+        currentProfile = fallback.data ? {
+          ...fallback.data,
+          latitude: undefined,
+          longitude: undefined,
+          timezone_offset: undefined,
+          birth_place_label: undefined,
+          birth_place_type: undefined,
+          birth_place_provider: undefined,
+          birth_place_provider_id: undefined,
+          timezone_id: undefined,
+          timezone_source: undefined,
+        } : null;
+        currentProfileError = fallback.error;
+      } else {
+        currentProfile = withoutDeclaredWindow.data;
+        currentProfileError = withoutDeclaredWindow.error;
+      }
     }
     if (currentProfileError) {
       return NextResponse.json({ error: "暂时无法核对现有出生资料" }, { status: 500 });
@@ -210,6 +244,12 @@ export async function PATCH(request: Request) {
       ...(payload.birth_time_period !== undefined
         ? { birth_time_period: payload.birth_time_period }
         : {}),
+      ...(payload.declared_window_start !== undefined
+        ? { declared_window_start: payload.declared_window_start }
+        : {}),
+      ...(payload.declared_window_end !== undefined
+        ? { declared_window_end: payload.declared_window_end }
+        : {}),
       ...(payload.birth_time_clue !== undefined
         ? { birth_time_clue: payload.birth_time_clue }
         : {}),
@@ -261,6 +301,30 @@ export async function PATCH(request: Request) {
       data = fallback.data;
       error = fallback.error;
     }
+    if (error && isMissingProfileColumn(error)) {
+      const {
+        declared_window_start: _start,
+        declared_window_end: _end,
+        ...withoutDeclaredWindow
+      } = withCoordinates;
+      void _start;
+      void _end;
+      const fallback = await writeProfile(withoutDeclaredWindow);
+      data = fallback.data;
+      error = fallback.error;
+    }
+    if (error && isMissingProfileColumn(error)) {
+      const {
+        declared_window_start: _start,
+        declared_window_end: _end,
+        ...withoutCoordinatesOrWindow
+      } = withoutCoordinates;
+      void _start;
+      void _end;
+      const fallback = await writeProfile(withoutCoordinatesOrWindow);
+      data = fallback.data;
+      error = fallback.error;
+    }
 
     if (!error && !data && invalidatesUnconfirmedApplication) {
       return NextResponse.json({
diff --git a/frontend/src/app/api/consult/route.ts b/frontend/src/app/api/consult/route.ts
index 8a043994..ed563592 100644
--- a/frontend/src/app/api/consult/route.ts
+++ b/frontend/src/app/api/consult/route.ts
@@ -341,7 +341,7 @@ export async function POST(request: Request) {
       async loadProfile(profileUserId) {
         const { data, error } = await supabase
           .from("profiles")
-          .select("name,birth_date,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,birth_time_status,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source")
+          .select("name,birth_date,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,declared_window_start,declared_window_end,birth_time_status,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source")
           .eq("id", profileUserId)
           .single();
         if (error || !data) throw new ConsultationProfileTruthError("profile_unavailable");
diff --git a/frontend/src/app/api/onboarding/route.ts b/frontend/src/app/api/onboarding/route.ts
index e6291810..ccab3ae5 100644
--- a/frontend/src/app/api/onboarding/route.ts
+++ b/frontend/src/app/api/onboarding/route.ts
@@ -20,7 +20,7 @@ function createProfileRepository(
     async loadProfile(userId) {
       return admin
         .from("profiles")
-        .select("id,name,birth_date,birth_time,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,birth_time_status,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source,onboarding_payload,onboarding_version,onboarding_generated_at")
+        .select("id,name,birth_date,birth_time,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,declared_window_start,declared_window_end,birth_time_clue,uncertainty_before_minutes,uncertainty_after_minutes,birth_time_status,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset,birth_place_label,birth_place_type,birth_place_provider,birth_place_provider_id,timezone_id,timezone_source,onboarding_payload,onboarding_version,onboarding_generated_at")
         .eq("id", userId)
         .maybeSingle();
     },
diff --git a/frontend/src/app/globals.css b/frontend/src/app/globals.css
index 900c86c5..ca82a8f6 100644
--- a/frontend/src/app/globals.css
+++ b/frontend/src/app/globals.css
@@ -2050,8 +2050,17 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
 .birth-time-source-option b { font-size: var(--type-body-sm); line-height: 1.35; }
 .birth-time-source-option small { font-size: var(--type-caption); line-height: 1.5; }
 .birth-time-detail-grid { grid-template-columns: minmax(0, .9fr) minmax(0, 1.1fr); gap: var(--space-3); padding: var(--space-4); border: 1px solid var(--color-border); border-radius: var(--radius-lg); background: var(--color-canvas-soft); }
-.birth-time-period-details { align-items: start; }
-.birth-time-period-details > label { align-self: start; }
+.birth-time-window-details { align-items: start; }
+.birth-time-window-details > label { align-self: start; }
+.birth-time-window-intro {
+  grid-column: 1 / -1;
+  margin: 0;
+  color: var(--color-ink-secondary);
+  font-size: var(--type-caption);
+  line-height: 1.5;
+}
+.birth-time-window-details .birth-time-skip-button { grid-column: 1 / -1; justify-self: start; min-height: 40px; padding-inline: 13px; border-color: transparent; background: transparent; color: var(--color-action); font-size: var(--type-caption); }
+.birth-time-window-details .birth-time-skip-button:hover { background: color-mix(in srgb, var(--color-action-soft) 72%, transparent); }
 .birth-time-detail-grid > label { gap: 7px; }
 .birth-time-detail-grid > label > span { color: var(--color-ink-secondary); font-size: var(--type-caption); font-weight: 700; }
 .birth-time-detail-grid textarea {
@@ -2081,8 +2090,6 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
 .birth-time-detail-grid textarea::-webkit-resizer {
   background: color-mix(in srgb, var(--color-border-strong) 70%, transparent);
 }
-.birth-time-period-details .birth-time-skip-button { grid-column: 1 / -1; justify-self: start; min-height: 40px; padding-inline: 13px; border-color: transparent; background: transparent; color: var(--color-action); font-size: var(--type-caption); }
-.birth-time-period-details .birth-time-skip-button:hover { background: color-mix(in srgb, var(--color-action-soft) 72%, transparent); }
 .birth-time-detail-note[role="status"] { display: grid; gap: var(--space-3); padding: var(--space-4); border: 1px solid var(--color-border); border-radius: var(--radius-md); background: var(--color-canvas-soft); }
 .birth-time-detail-note[role="status"] p { margin: 0; }
 .onboarding-card-actions { align-items: center; justify-content: space-between; gap: var(--space-4); padding-top: var(--space-2); }
@@ -2091,7 +2098,7 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
 @media (max-width: 620px) {
   .onboarding-card-heading { align-items: flex-start; flex-direction: column; gap: var(--space-2); }
   .birth-time-source-list, .birth-time-detail-grid { grid-template-columns: 1fr; }
-  .birth-time-period-details .birth-time-skip-button { grid-column: auto; justify-self: stretch; }
+  .birth-time-window-details .birth-time-skip-button { grid-column: auto; justify-self: stretch; }
   .onboarding-card-actions { align-items: stretch; flex-direction: column; }
   .onboarding-card-actions .button-primary { width: 100%; }
 }
diff --git a/frontend/src/app/page.tsx b/frontend/src/app/page.tsx
index 32cd6de1..110780d9 100644
--- a/frontend/src/app/page.tsx
+++ b/frontend/src/app/page.tsx
@@ -61,6 +61,7 @@ import {
   birthTimePersistenceValues,
   declaredBirthInputChanged,
   describeBirthTimeDraft,
+  hydrateDeclaredWindowDraft,
   isDeclaredBirthProfileComplete,
   isBirthTimeDraftReady,
   birthTimeDraftReadyHint,
@@ -358,6 +359,8 @@ const emptyProfile: Profile = {
   reportedTime: "",
   birthTimeSource: "",
   birthTimePeriod: "",
+  declaredWindowStart: "",
+  declaredWindowEnd: "",
   birthTimeClue: "",
   uncertaintyBeforeMinutes: null,
   uncertaintyAfterMinutes: null,
@@ -659,6 +662,8 @@ function readProfile(value: unknown): Profile {
     active_birth_time?: unknown;
     birth_time_source?: unknown;
     birth_time_period?: unknown;
+    declared_window_start?: unknown;
+    declared_window_end?: unknown;
     birth_time_clue?: unknown;
     uncertainty_before_minutes?: unknown;
     uncertainty_after_minutes?: unknown;
@@ -696,6 +701,13 @@ function readProfile(value: unknown): Profile {
   const reportedTime = persistedReportedTime || (source === "legacy_import" ? time : "");
   const knownPeriods = ["early_morning", "morning", "afternoon", "evening", "late_night"] as const;
   const period = knownPeriods.find((item) => item === profile.birth_time_period) ?? "";
+  const windowStart = typeof profile.declared_window_start === "string" ? profile.declared_window_start.slice(0, 5) : "";
+  const windowEnd = typeof profile.declared_window_end === "string" ? profile.declared_window_end.slice(0, 5) : "";
+  const declaredWindow = hydrateDeclaredWindowDraft({
+    period,
+    start: windowStart,
+    end: windowEnd,
+  });
   const knownStatuses = ["reported", "assessing", "rectifying", "candidate", "accepted", "confirmed"] as const;
   const status = knownStatuses.find((item) => item === profile.birth_time_status)
     ?? (time ? "confirmed" : "");
@@ -723,8 +735,10 @@ function readProfile(value: unknown): Profile {
     time: typeof time === "string" ? time : "",
     reportedTime: typeof reportedTime === "string" ? reportedTime : "",
     birthTimeSource: source,
-    birthTimePeriod: period,
-    birthTimeClue: typeof profile.birth_time_clue === "string" ? profile.birth_time_clue.slice(0, 240) : "",
+    birthTimePeriod: declaredWindow.birthTimePeriod,
+    declaredWindowStart: declaredWindow.declaredWindowStart,
+    declaredWindowEnd: declaredWindow.declaredWindowEnd,
+    birthTimeClue: "",
     uncertaintyBeforeMinutes: typeof profile.uncertainty_before_minutes === "number" ? profile.uncertainty_before_minutes : null,
     uncertaintyAfterMinutes: typeof profile.uncertainty_after_minutes === "number" ? profile.uncertainty_after_minutes : null,
     birthTimeStatus: status,
@@ -1475,7 +1489,9 @@ export default function Home() {
               time: isCompletedCandidatePreview ? "04:53" : isRectificationPreview || isAssessmentLoadingPreview ? "" : "12:30",
               reportedTime: isRectificationPreview ? "14:30" : isAssessmentLoadingPreview || isCompletedCandidatePreview ? "" : "12:30",
               birthTimeSource: isRectificationPreview ? "approximate" : isAssessmentLoadingPreview || isCompletedCandidatePreview ? "period_only" : "legacy_import",
-              birthTimePeriod: isAssessmentLoadingPreview || isCompletedCandidatePreview ? "early_morning" : "",
+              ...hydrateDeclaredWindowDraft({
+                period: isAssessmentLoadingPreview || isCompletedCandidatePreview ? "early_morning" : "",
+              }),
               birthTimeClue: "",
               uncertaintyBeforeMinutes: isRectificationPreview ? 30 : null,
               uncertaintyAfterMinutes: isRectificationPreview ? 30 : null,
diff --git a/frontend/src/components/birth-time-intake.tsx b/frontend/src/components/birth-time-intake.tsx
index fb015225..bd67915c 100644
--- a/frontend/src/components/birth-time-intake.tsx
+++ b/frontend/src/components/birth-time-intake.tsx
@@ -6,7 +6,6 @@ import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@
 import { birthTimeConsultationOptionsCopy } from "@/lib/birth-time-consultation-consent";
 import {
   birthTimeDisplayState,
-  birthTimePeriodOptions,
   birthTimeSourceDefaults,
   birthTimeSourceOptions,
   type BirthTimeDraft,
@@ -30,9 +29,18 @@ function splitBirthTime(value: string) {
 type BirthClockSelectProps = {
   readonly value: string;
   readonly onChange: (value: string) => void;
+  readonly ariaLabel?: string;
+  readonly hourLabel?: string;
+  readonly minuteLabel?: string;
 };
 
-function BirthClockSelect({ value, onChange }: BirthClockSelectProps) {
+function BirthClockSelect({
+  value,
+  onChange,
+  ariaLabel = "选择出生时间",
+  hourLabel = "出生时间小时",
+  minuteLabel = "出生时间分钟",
+}: BirthClockSelectProps) {
   const currentTime = value || "";
   const [timeParts, setTimeParts] = useState(() => splitBirthTime(currentTime));
 
@@ -44,9 +52,9 @@ function BirthClockSelect({ value, onChange }: BirthClockSelectProps) {
   };
 
   return (
-    <div className="birth-time-clock-selects" aria-label="选择出生时间">
+    <div className="birth-time-clock-selects" aria-label={ariaLabel}>
       <Select required value={timeParts.hour || null} onValueChange={(nextValue) => patchTime("hour", nextValue)}>
-        <SelectTrigger aria-label="出生时间小时">
+        <SelectTrigger aria-label={hourLabel}>
           <SelectValue placeholder="时" />
         </SelectTrigger>
         <SelectContent className="birth-time-clock-menu" style={{ width: 108, minWidth: 108 }}>
@@ -55,7 +63,7 @@ function BirthClockSelect({ value, onChange }: BirthClockSelectProps) {
       </Select>
       <span className="birth-time-clock-separator" aria-hidden="true">:</span>
       <Select required value={timeParts.minute || null} onValueChange={(nextValue) => patchTime("minute", nextValue)}>
-        <SelectTrigger aria-label="出生时间分钟">
+        <SelectTrigger aria-label={minuteLabel}>
           <SelectValue placeholder="分" />
         </SelectTrigger>
         <SelectContent className="birth-time-clock-menu" style={{ width: 108, minWidth: 108 }}>
@@ -168,36 +176,28 @@ export function BirthTimeIntakeFields({ value, onPatch }: BirthTimeIntakeProps)
       )}
 
       {source === "period_only" && (
-        <div className="birth-time-detail-grid birth-time-period-details onboarding-card-reveal">
+        <div className="birth-time-detail-grid birth-time-window-details onboarding-card-reveal">
+          <p className="birth-time-window-intro">选择你记得的开始和结束时间。可以跨午夜，例如 23:00 到 03:59。</p>
           <label>
-            <span>请选择最接近的时间范围</span>
-            <Select
-              required
-              value={value.birthTimePeriod || null}
-              onValueChange={(nextValue) => {
-                if (typeof nextValue === "string") onPatch({ birthTimePeriod: nextValue });
-              }}
-            >
-              <SelectTrigger aria-label="最接近的时间范围">
-                <SelectValue placeholder="请选择大致时段">
-                  {(selectedValue) => birthTimePeriodOptions.find((option) => option.value === selectedValue)?.label ?? "请选择大致时段"}
-                </SelectValue>
-              </SelectTrigger>
-              <SelectContent>
-                {birthTimePeriodOptions.map((option) => (
-                  <SelectItem key={option.value} value={option.value}>{option.label}</SelectItem>
-                ))}
-              </SelectContent>
-            </Select>
+            <span>开始</span>
+            <BirthClockSelect
+              key={`start-${value.declaredWindowStart}`}
+              value={value.declaredWindowStart}
+              ariaLabel="选择开始时间"
+              hourLabel="开始小时"
+              minuteLabel="开始分钟"
+              onChange={(declaredWindowStart) => onPatch({ declaredWindowStart })}
+            />
           </label>
           <label>
-            <span>补充描述（可选）</span>
-            <textarea
-              maxLength={240}
-              placeholder="例如：天刚亮、午饭前后、家人记得大约 6—8 点"
-              rows={2}
-              value={value.birthTimeClue}
-              onChange={(event) => onPatch({ birthTimeClue: event.target.value })}
+            <span>结束</span>
+            <BirthClockSelect
+              key={`end-${value.declaredWindowEnd}`}
+              value={value.declaredWindowEnd}
+              ariaLabel="选择结束时间"
+              hourLabel="结束小时"
+              minuteLabel="结束分钟"
+              onChange={(declaredWindowEnd) => onPatch({ declaredWindowEnd })}
             />
           </label>
           <button
@@ -207,6 +207,8 @@ export function BirthTimeIntakeFields({ value, onPatch }: BirthTimeIntakeProps)
               birthTimeSource: "unknown",
               reportedTime: "",
               birthTimePeriod: "",
+              declaredWindowStart: "",
+              declaredWindowEnd: "",
               birthTimeClue: "",
               uncertaintyBeforeMinutes: null,
               uncertaintyAfterMinutes: null,
@@ -224,7 +226,7 @@ export function BirthTimeIntakeFields({ value, onPatch }: BirthTimeIntakeProps)
             className="button-secondary"
             type="button"
             onClick={() => onPatch({ birthTimeSource: "period_only", birthTimeStatus: "reported" })}
-          >我可以描述一个时间范围</button>
+          >我可以选一段时间范围</button>
         </div>
       )}
     </div>
diff --git a/frontend/src/lib/account-profile-patch.ts b/frontend/src/lib/account-profile-patch.ts
index af97c35d..014fee12 100644
--- a/frontend/src/lib/account-profile-patch.ts
+++ b/frontend/src/lib/account-profile-patch.ts
@@ -34,6 +34,8 @@ export const accountProfilePatchSchema = z.object({
   reported_birth_time: nullableBirthClock.optional(),
   birth_time_source: birthTimeSourceSchema.nullable().optional(),
   birth_time_period: birthTimePeriodSchema.nullable().optional(),
+  declared_window_start: nullableBirthClock.optional(),
+  declared_window_end: nullableBirthClock.optional(),
   birth_time_clue: nullableTrimmedString(240).optional(),
   uncertainty_before_minutes: z.number().int().min(0).max(720).nullable().optional(),
   uncertainty_after_minutes: z.number().int().min(0).max(720).nullable().optional(),
@@ -66,6 +68,8 @@ export const accountProfilePatchSchema = z.object({
     "reported_birth_time",
     "birth_time_source",
     "birth_time_period",
+    "declared_window_start",
+    "declared_window_end",
     "birth_time_clue",
     "uncertainty_before_minutes",
     "uncertainty_after_minutes",
@@ -95,7 +99,8 @@ export const accountProfilePatchSchema = z.object({
     if (value.birth_date !== undefined && value.birth_date !== null) {
       addIssue("birth_time_source", "填写出生日期后必须说明时间来源");
     }
-    if (time || value.birth_time || value.birth_time_period || value.birth_time_clue
+    if (time || value.birth_time || value.birth_time_period || value.declared_window_start
+      || value.declared_window_end || value.birth_time_clue
       || before != null || after != null) {
       addIssue("birth_time_source", "未选择时间来源时不得提交时间或误差范围");
     }
@@ -109,6 +114,11 @@ export const accountProfilePatchSchema = z.object({
   const ensureNoPeriod = () => {
     if (value.birth_time_period) addIssue("birth_time_period", "具体时间来源不得同时提交时段");
   };
+  const ensureNoDeclaredWindow = () => {
+    if (value.declared_window_start || value.declared_window_end) {
+      addIssue("declared_window_start", "具体时间来源不得同时提交开始结束范围");
+    }
+  };
   const ensureNoUncertainty = () => {
     if (before != null || after != null) {
       addIssue("uncertainty_before_minutes", "该时间来源不得提交误差范围");
@@ -119,29 +129,44 @@ export const accountProfilePatchSchema = z.object({
     if (!time) addIssue("reported_birth_time", "医院记录需要具体时间");
     if (before !== 2 || after !== 2) addIssue("uncertainty_before_minutes", "医院记录固定检查前后 2 分钟");
     ensureNoPeriod();
+    ensureNoDeclaredWindow();
   } else if (source === "family_exact") {
     if (!time) addIssue("reported_birth_time", "家人记忆需要具体时间");
     if (![0, 5, 10, 15].includes(before ?? -1) || before !== after) {
       addIssue("uncertainty_before_minutes", "准确时间填报必须前后一致");
     }
     ensureNoPeriod();
+    ensureNoDeclaredWindow();
   } else if (source === "approximate") {
     if (!time) addIssue("reported_birth_time", "大概时间需要具体 HH:mm");
     if (![15, 30, 60].includes(before ?? -1) || before !== after) {
       addIssue("uncertainty_before_minutes", "大概时间误差必须为前后 15、30 或 60 分钟");
     }
     ensureNoPeriod();
+    ensureNoDeclaredWindow();
   } else if (source === "legacy_import") {
     if (!time && !value.birth_time) addIssue("reported_birth_time", "既有资料需要具体时间");
     ensureNoPeriod();
+    ensureNoDeclaredWindow();
     ensureNoUncertainty();
   } else if (source === "period_only") {
-    if (!value.birth_time_period) addIssue("birth_time_period", "只知道时段时必须选择时段");
+    const start = value.declared_window_start;
+    const end = value.declared_window_end;
+    const hasWindow = Boolean(start && end && start !== end);
+    if (!hasWindow && !value.birth_time_period) {
+      addIssue("declared_window_start", "不确定准确时间时必须选择开始和结束时间");
+    }
+    if ((start && !end) || (!start && end) || (start && end && start === end)) {
+      addIssue("declared_window_end", "开始和结束必须是不同的钟点");
+    }
     if (time) addIssue("reported_birth_time", "只知道时段时不得同时提交具体分钟");
     ensureNoUncertainty();
   } else if (source === "unknown") {
     if (time) addIssue("reported_birth_time", "时间未知时不得提交具体分钟");
     if (value.birth_time_period) addIssue("birth_time_period", "时间未知时不得提交确定时段");
+    if (value.declared_window_start || value.declared_window_end) {
+      addIssue("declared_window_start", "时间未知时不得提交开始结束范围");
+    }
     ensureNoUncertainty();
   }
 
@@ -154,6 +179,8 @@ type AccountBirthTimeState = Readonly<{
   reported_birth_time: string | null;
   birth_time_source: string | null;
   birth_time_period: string | null;
+  declared_window_start?: string | null;
+  declared_window_end?: string | null;
   birth_time_clue: string | null;
   uncertainty_before_minutes: number | null;
   uncertainty_after_minutes: number | null;
@@ -181,6 +208,8 @@ const declarationFields = [
   "reported_birth_time",
   "birth_time_source",
   "birth_time_period",
+  "declared_window_start",
+  "declared_window_end",
   "birth_time_clue",
   "uncertainty_before_minutes",
   "uncertainty_after_minutes",
diff --git a/frontend/src/lib/birth-profile-timezone.ts b/frontend/src/lib/birth-profile-timezone.ts
index 719aee26..046bc4ec 100644
--- a/frontend/src/lib/birth-profile-timezone.ts
+++ b/frontend/src/lib/birth-profile-timezone.ts
@@ -46,6 +46,8 @@ export function birthProfileReferenceTime(value: unknown, preferredTime?: string
   const direct = text(profile ? valueFor(profile, "birth_time", "time") : null)?.slice(0, 5);
   if (direct && /^([01]\d|2[0-3]):[0-5]\d$/.test(direct)) return direct;
   const period = text(profile ? valueFor(profile, "birth_time_period", "birthTimePeriod") : null);
+  const windowStart = text(profile ? valueFor(profile, "declared_window_start", "declaredWindowStart") : null)?.slice(0, 5);
+  if (windowStart && /^([01]\d|2[0-3]):[0-5]\d$/.test(windowStart)) return windowStart;
   return {
     early_morning: "06:00",
     morning: "10:00",
diff --git a/frontend/src/lib/birth-time-intake-model.ts b/frontend/src/lib/birth-time-intake-model.ts
index 03a253ba..866aa102 100644
--- a/frontend/src/lib/birth-time-intake-model.ts
+++ b/frontend/src/lib/birth-time-intake-model.ts
@@ -1,5 +1,9 @@
 import { format, isValid, parse } from "date-fns";
 import type { JourneySnapshot } from "./birth-time-journey.ts";
+import {
+  declaredClockRange,
+  matchingDeclaredPeriod,
+} from "./declared-birth-window.ts";
 
 const birthDatePattern = "yyyy-MM-dd";
 const birthClockPattern = /^(?:[01]\d|2[0-3]):[0-5]\d$/;
@@ -38,6 +42,8 @@ export type BirthTimeDraft = {
   readonly reportedTime: string;
   readonly birthTimeSource: BirthTimeSource;
   readonly birthTimePeriod: BirthTimePeriod;
+  readonly declaredWindowStart: string;
+  readonly declaredWindowEnd: string;
   readonly birthTimeClue: string;
   readonly uncertaintyBeforeMinutes: number | null;
   readonly uncertaintyAfterMinutes: number | null;
@@ -84,30 +90,39 @@ export function formatBirthDate(value: Date): string {
 
 export const birthTimeSourceOptions = [
   { value: "family_exact", label: "我知道准确出生时间", hint: "按医院记录或家人记得的时间填写，精确到分钟" },
-  { value: "period_only", label: "我不确定准确时间", hint: "只知道大概几点、上午下午，或完全不清楚" },
+  { value: "period_only", label: "我不确定准确时间", hint: "选择一段开始到结束的时间，或完全不清楚" },
 ] as const;
 
 export const birthTimeSourceDefaults = {
   hospital_record: {
     birthTimePeriod: "",
+    declaredWindowStart: "",
+    declaredWindowEnd: "",
     birthTimeClue: "",
     uncertaintyBeforeMinutes: 2,
     uncertaintyAfterMinutes: 2,
   },
   family_exact: {
     birthTimePeriod: "",
+    declaredWindowStart: "",
+    declaredWindowEnd: "",
     birthTimeClue: "",
     uncertaintyBeforeMinutes: 0,
     uncertaintyAfterMinutes: 0,
   },
   approximate: {
     birthTimePeriod: "",
+    declaredWindowStart: "",
+    declaredWindowEnd: "",
     birthTimeClue: "",
     uncertaintyBeforeMinutes: 30,
     uncertaintyAfterMinutes: 30,
   },
   period_only: {
     reportedTime: "",
+    birthTimePeriod: "",
+    declaredWindowStart: "",
+    declaredWindowEnd: "",
     birthTimeClue: "",
     uncertaintyBeforeMinutes: null,
     uncertaintyAfterMinutes: null,
@@ -115,6 +130,8 @@ export const birthTimeSourceDefaults = {
   unknown: {
     reportedTime: "",
     birthTimePeriod: "",
+    declaredWindowStart: "",
+    declaredWindowEnd: "",
     uncertaintyBeforeMinutes: null,
     uncertaintyAfterMinutes: null,
   },
@@ -136,8 +153,8 @@ export type BirthTimeDisplayState = {
 
 function reportedBirthTimeLabel(draft: BirthTimeDraft): string {
   if (draft.birthTimeSource === "period_only") {
-    return birthTimePeriodOptions.find((option) => option.value === draft.birthTimePeriod)?.label
-      ?? "未选择时段";
+    const range = declaredWindowRangeForDraft(draft);
+    return range ? range.label : "未选择时间范围";
   }
   if (draft.birthTimeSource === "unknown") return "具体时间未知";
   return draft.reportedTime || draft.time || "尚未填报";
@@ -155,15 +172,6 @@ export function birthTimeDisplayState(draft: BirthTimeDraft): BirthTimeDisplaySt
   };
 }
 
-const periodLabels = {
-  "": "未选择时段",
-  early_morning: "凌晨或清晨",
-  morning: "上午",
-  afternoon: "下午",
-  evening: "晚上",
-  late_night: "深夜",
-} as const satisfies Record<BirthTimePeriod, string>;
-
 const intentCopy = {
   confirm_stable_record: "医院记录前后两分钟内结构稳定，可以直接作为当前排盘时间。",
   explain_sensitive_boundary: "这个时间靠近敏感边界，需要先做轻量校正，暂不直接排盘。",
@@ -185,6 +193,38 @@ export function assistantIntentCopy(intent: JourneySnapshot["assistantIntent"])
   return intentCopy[intent];
 }
 
+export function declaredWindowRangeForDraft(draft: Pick<BirthTimeDraft, "birthTimeSource" | "birthTimePeriod" | "declaredWindowStart" | "declaredWindowEnd">) {
+  return declaredClockRange({
+    source: draft.birthTimeSource || "period_only",
+    period: draft.birthTimePeriod || null,
+    startTime: draft.declaredWindowStart || null,
+    endTime: draft.declaredWindowEnd || null,
+  });
+}
+
+export function hydrateDeclaredWindowDraft(input: {
+  readonly period?: string | null;
+  readonly start?: string | null;
+  readonly end?: string | null;
+}): Pick<BirthTimeDraft, "birthTimePeriod" | "declaredWindowStart" | "declaredWindowEnd"> {
+  const period = birthTimePeriodOptions.some((option) => option.value === input.period)
+    ? input.period as BirthTimePeriod
+    : "";
+  const range = declaredClockRange({
+    source: "period_only",
+    period: period || null,
+    startTime: input.start,
+    endTime: input.end,
+  });
+  return {
+    birthTimePeriod: range
+      ? matchingDeclaredPeriod(range.startTime, range.endTime) ?? ""
+      : period,
+    declaredWindowStart: range?.startTime ?? "",
+    declaredWindowEnd: range?.endTime ?? "",
+  };
+}
+
 export function isBirthTimeDraftReady(draft: BirthTimeDraft) {
   if (!parseBirthDate(draft.date) || draft.birthTimeClue.length > 240) return false;
   switch (draft.birthTimeSource) {
@@ -205,7 +245,7 @@ export function isBirthTimeDraftReady(draft: BirthTimeDraft) {
         && (draft.uncertaintyAfterMinutes === null
           || draft.uncertaintyBeforeMinutes === draft.uncertaintyAfterMinutes);
     case "period_only":
-      return birthTimePeriodOptions.some((option) => option.value === draft.birthTimePeriod)
+      return Boolean(declaredWindowRangeForDraft(draft))
         && !draft.reportedTime
         && draft.uncertaintyBeforeMinutes === null
         && draft.uncertaintyAfterMinutes === null;
@@ -227,7 +267,13 @@ export function birthTimeDraftReadyHint(draft: BirthTimeDraft) {
   if (!parseBirthDate(draft.date)) return "请先选择出生日期";
   if (!draft.birthTimeSource) return "请选择你对出生时间了解多少";
   if (isBirthTimeDraftReady(draft)) return "";
-  if (draft.birthTimeSource === "period_only") return "请选择一个大致时段";
+  if (draft.birthTimeSource === "period_only") {
+    if (draft.declaredWindowStart && draft.declaredWindowEnd
+      && draft.declaredWindowStart === draft.declaredWindowEnd) {
+      return "开始和结束不能是同一分钟";
+    }
+    return "请选择开始和结束时间";
+  }
   if (draft.birthTimeSource === "unknown") return "";
   return "请填写时和分";
 }
@@ -266,6 +312,8 @@ const declaredBirthInputKeys = [
   "reportedTime",
   "birthTimeSource",
   "birthTimePeriod",
+  "declaredWindowStart",
+  "declaredWindowEnd",
   "birthTimeClue",
   "uncertaintyBeforeMinutes",
   "uncertaintyAfterMinutes",
@@ -316,11 +364,19 @@ export function birthTimePersistenceValues(draft: BirthTimeDraft) {
       : draft.birthTimeSource === "approximate"
         ? draft.uncertaintyBeforeMinutes ?? birthTimeSourceDefaults.approximate.uncertaintyBeforeMinutes
         : null;
+  const declaredRange = draft.birthTimeSource === "period_only"
+    ? declaredWindowRangeForDraft(draft)
+    : null;
+  const matchedPeriod = declaredRange
+    ? matchingDeclaredPeriod(declaredRange.startTime, declaredRange.endTime)
+    : null;
   return {
     reported_birth_time: reportedTime,
     birth_time_source: draft.birthTimeSource || null,
-    birth_time_period: draft.birthTimePeriod || null,
-    birth_time_clue: draft.birthTimeClue.trim() || null,
+    birth_time_period: matchedPeriod,
+    declared_window_start: declaredRange?.startTime ?? null,
+    declared_window_end: declaredRange?.endTime ?? null,
+    birth_time_clue: null,
     uncertainty_before_minutes: uncertainty,
     uncertainty_after_minutes: uncertainty,
   };
@@ -361,8 +417,10 @@ export function describeBirthTimeDraft(draft: BirthTimeDraft) {
       return `${date} ${draft.reportedTime}（填报准确时间）`;
     case "approximate":
       return `${date}，约 ${draft.reportedTime}`;
-    case "period_only":
-      return `${date}，${periodLabels[draft.birthTimePeriod]}${draft.birthTimeClue.trim() ? `（${draft.birthTimeClue.trim()}）` : ""}`;
+    case "period_only": {
+      const range = declaredWindowRangeForDraft(draft);
+      return `${date}，${range ? range.label : "未选择时间范围"}`;
+    }
     case "unknown":
       return `${date}，具体时间未知`;
     case "legacy_import":
diff --git a/frontend/src/lib/consultation-route-service.ts b/frontend/src/lib/consultation-route-service.ts
index f7537d52..1cdf3731 100644
--- a/frontend/src/lib/consultation-route-service.ts
+++ b/frontend/src/lib/consultation-route-service.ts
@@ -2,7 +2,7 @@ import { chinaLocations } from "../data/china-locations.ts";
 import { isBirthClockTime, parseBirthDate } from "./birth-time-intake-model.ts";
 import { resolveMissingBirthTimezoneOffset } from "./birth-profile-timezone.ts";
 import {
-  declaredClockRange,
+  declaredClockRangeFromProfile,
   declaredRangeWrapsMidnight,
 } from "./declared-birth-window.ts";
 import {
@@ -367,7 +367,7 @@ function declaredWindowFromProfile(value: unknown): DeclaredBirthWindowConsultat
     throw new ConsultationProfileTruthError("mode_changed");
   }
   const birthTimePeriod = optionalText(profile, "birth_time_period");
-  const range = declaredClockRange({ source: birthTimeSource, period: birthTimePeriod });
+  const range = declaredClockRangeFromProfile(profile);
   if (!range) throw new ConsultationProfileTruthError("profile_incomplete");
 
   const countryCode = optionalText(profile, "country_code");
@@ -481,10 +481,7 @@ export async function prepareConsultationRoute<Reservation, GuardResult>(
     }
     serverChart = serverChartFromProfile(profile, consultationMode);
   } else if (consultationMode === "declared_birth_window") {
-    const range = declaredClockRange({
-      source: optionalText(record(profile) ?? {}, "birth_time_source") ?? "",
-      period: optionalText(record(profile) ?? {}, "birth_time_period"),
-    });
+    const range = declaredClockRangeFromProfile(record(profile) ?? {});
     try {
       profile = await (input.resolveTimezoneOffset ?? ((value, time) => (
         resolveMissingBirthTimezoneOffset(value, { preferredTime: time })
diff --git a/frontend/src/lib/declared-birth-window.ts b/frontend/src/lib/declared-birth-window.ts
index fde44181..4dc0b9ca 100644
--- a/frontend/src/lib/declared-birth-window.ts
+++ b/frontend/src/lib/declared-birth-window.ts
@@ -111,18 +111,61 @@ export function declaredWindowProbeRole(
   return "interior";
 }
 
+function customDeclaredRange(startTime: string | null | undefined, endTime: string | null | undefined): DeclaredClockRange | null {
+  if (!isBirthClockText(startTime) || !isBirthClockText(endTime) || startTime === endTime) return null;
+  return {
+    label: `${startTime}—${endTime}`,
+    startTime,
+    endTime,
+  };
+}
+
+export function matchingDeclaredPeriod(startTime: string, endTime: string): DeclaredBirthPeriod | null {
+  for (const period of DECLARED_PERIOD_IDS) {
+    const range = DECLARED_PERIOD_RANGES[period];
+    if (range.startTime === startTime && range.endTime === endTime) return period;
+  }
+  return null;
+}
+
 export function declaredClockRange(input: Readonly<{
   source: string;
   period?: string | null;
+  startTime?: string | null;
+  endTime?: string | null;
 }>): DeclaredClockRange | null {
+  const custom = customDeclaredRange(input.startTime, input.endTime);
   if (input.source === "period_only") {
-    return isDeclaredBirthPeriod(input.period) ? DECLARED_PERIOD_RANGES[input.period] : null;
+    return custom ?? (isDeclaredBirthPeriod(input.period) ? DECLARED_PERIOD_RANGES[input.period] : null);
   }
-  if (input.source === "legacy_import" && isDeclaredBirthPeriod(input.period)) {
-    return DECLARED_PERIOD_RANGES[input.period];
+  if (input.source === "legacy_import" && (custom || isDeclaredBirthPeriod(input.period))) {
+    return custom ?? DECLARED_PERIOD_RANGES[input.period as DeclaredBirthPeriod];
   }
   if (input.source === "unknown" || input.source === "legacy_import") {
     return UNKNOWN_DECLARED_CLOCK_RANGE;
   }
   return null;
 }
+
+function textClock(value: unknown): string | null {
+  return typeof value === "string" && isBirthClockText(value.slice(0, 5)) ? value.slice(0, 5) : null;
+}
+
+export function declaredClockRangeFromProfile(profile: Readonly<Record<string, unknown>>): DeclaredClockRange | null {
+  const source = typeof profile.birth_time_source === "string"
+    ? profile.birth_time_source
+    : typeof profile.birthTimeSource === "string"
+      ? profile.birthTimeSource
+      : "";
+  const period = typeof profile.birth_time_period === "string"
+    ? profile.birth_time_period
+    : typeof profile.birthTimePeriod === "string"
+      ? profile.birthTimePeriod
+      : null;
+  return declaredClockRange({
+    source,
+    period,
+    startTime: textClock(profile.declared_window_start ?? profile.declaredWindowStart),
+    endTime: textClock(profile.declared_window_end ?? profile.declaredWindowEnd),
+  });
+}
diff --git a/frontend/src/lib/onboarding-cache-policy.ts b/frontend/src/lib/onboarding-cache-policy.ts
index 1e3a41d6..349e32ba 100644
--- a/frontend/src/lib/onboarding-cache-policy.ts
+++ b/frontend/src/lib/onboarding-cache-policy.ts
@@ -13,6 +13,8 @@ type OnboardingProfileInput = {
   readonly activeBirthTime: string | null;
   readonly birthTimeSource?: string | null;
   readonly birthTimePeriod?: string | null;
+  readonly declaredWindowStart?: string | null;
+  readonly declaredWindowEnd?: string | null;
   readonly birthTimeClue?: string | null;
   readonly uncertaintyBeforeMinutes?: number | null;
   readonly uncertaintyAfterMinutes?: number | null;
@@ -56,6 +58,8 @@ export function createOnboardingCacheIdentity(
       profile.activeBirthTime,
       profile.birthTimeSource,
       profile.birthTimePeriod,
+      profile.declaredWindowStart,
+      profile.declaredWindowEnd,
       profile.birthTimeClue,
       profile.uncertaintyBeforeMinutes,
       profile.uncertaintyAfterMinutes,
diff --git a/frontend/src/lib/onboarding-client.ts b/frontend/src/lib/onboarding-client.ts
index 58746c8e..f4cc49c7 100644
--- a/frontend/src/lib/onboarding-client.ts
+++ b/frontend/src/lib/onboarding-client.ts
@@ -76,6 +76,8 @@ type OnboardingProfileFingerprintInput = {
   readonly reportedTime: string;
   readonly birthTimeSource: string;
   readonly birthTimePeriod: string;
+  readonly declaredWindowStart: string;
+  readonly declaredWindowEnd: string;
   readonly birthTimeClue: string;
   readonly uncertaintyBeforeMinutes: number | null;
   readonly uncertaintyAfterMinutes: number | null;
@@ -142,6 +144,8 @@ export function onboardingProfileFingerprint(profile: OnboardingProfileFingerpri
     profile.reportedTime,
     profile.birthTimeSource,
     profile.birthTimePeriod,
+    profile.declaredWindowStart,
+    profile.declaredWindowEnd,
     profile.birthTimeClue,
     profile.uncertaintyBeforeMinutes,
     profile.uncertaintyAfterMinutes,
diff --git a/frontend/src/lib/onboarding-post.ts b/frontend/src/lib/onboarding-post.ts
index b7d5f21e..4877afcc 100644
--- a/frontend/src/lib/onboarding-post.ts
+++ b/frontend/src/lib/onboarding-post.ts
@@ -10,6 +10,7 @@ import {
 } from "./onboarding-payload.ts";
 import {
   formatBirthDate,
+  hydrateDeclaredWindowDraft,
   isDeclaredBirthProfileComplete,
   type BirthTimeSource,
   type BirthTimeStatus,
@@ -24,6 +25,8 @@ export type OnboardingProfileRow = {
   readonly active_birth_time: string | null;
   readonly birth_time_source: string | null;
   readonly birth_time_period: string | null;
+  readonly declared_window_start?: string | null;
+  readonly declared_window_end?: string | null;
   readonly birth_time_clue: string | null;
   readonly uncertainty_before_minutes: number | null;
   readonly uncertainty_after_minutes: number | null;
@@ -103,21 +106,20 @@ function hasCompleteBirthProfile(profile: OnboardingProfileRow): boolean {
   ];
   const status = knownStatuses.find((item) => item === profile.birth_time_status)
     ?? (persistedTime ? "confirmed" : "");
-  const clock = (value: string | null) => value ? value.slice(0, 5) : "";
+  const clock = (value: string | null | undefined) => value ? value.slice(0, 5) : "";
+  const declaredWindow = hydrateDeclaredWindowDraft({
+    period: profile.birth_time_period,
+    start: profile.declared_window_start,
+    end: profile.declared_window_end,
+  });
   const birthDraft = {
     date: normalizeBirthDate(profile.birth_date),
     time: clock(persistedTime),
     reportedTime: clock(profile.reported_birth_time)
       || (source === "legacy_import" ? clock(persistedTime) : ""),
     birthTimeSource: source,
-    birthTimePeriod: profile.birth_time_period === "early_morning"
-      || profile.birth_time_period === "morning"
-      || profile.birth_time_period === "afternoon"
-      || profile.birth_time_period === "evening"
-      || profile.birth_time_period === "late_night"
-      ? profile.birth_time_period
-      : "",
-    birthTimeClue: profile.birth_time_clue ?? "",
+    ...declaredWindow,
+    birthTimeClue: "",
     uncertaintyBeforeMinutes: profile.uncertainty_before_minutes,
     uncertaintyAfterMinutes: profile.uncertainty_after_minutes,
     birthTimeStatus: status,
@@ -181,6 +183,8 @@ export function createOnboardingPost(dependencies: OnboardingPostDependencies):
       activeBirthTime: profile.active_birth_time,
       birthTimeSource: profile.birth_time_source,
       birthTimePeriod: profile.birth_time_period,
+      declaredWindowStart: profile.declared_window_start,
+      declaredWindowEnd: profile.declared_window_end,
       birthTimeClue: profile.birth_time_clue,
       uncertaintyBeforeMinutes: profile.uncertainty_before_minutes,
       uncertaintyAfterMinutes: profile.uncertainty_after_minutes,
diff --git a/frontend/src/lib/rectification-agentic/session.ts b/frontend/src/lib/rectification-agentic/session.ts
index 18a999d7..75d358ae 100644
--- a/frontend/src/lib/rectification-agentic/session.ts
+++ b/frontend/src/lib/rectification-agentic/session.ts
@@ -5,6 +5,7 @@ import type {
   AgenticRectificationContext,
 } from "@/mastra/rectification-tools";
 import { normalizePersistedBirthDate } from "../birth-time-intake-model.ts";
+import { declaredClockRange } from "../declared-birth-window.ts";
 
 type AccountingClient = SupabaseClient;
 
@@ -52,14 +53,6 @@ const timeValue = (value: unknown): string | null => {
   return /^([01]\d|2[0-3]):[0-5]\d$/.test(time) ? time : null;
 };
 
-const periodRanges = {
-  early_morning: { start_time: "04:00", end_time: "07:59" },
-  morning: { start_time: "08:00", end_time: "11:59" },
-  afternoon: { start_time: "12:00", end_time: "17:59" },
-  evening: { start_time: "18:00", end_time: "22:59" },
-  late_night: { start_time: "23:00", end_time: "03:59" },
-} as const;
-
 function shiftedTime(time: string, offsetMinutes: number): string {
   const [hour = 0, minute = 0] = time.split(":").map(Number);
   const normalized = ((hour * 60 + minute + offsetMinutes) % 1_440 + 1_440) % 1_440;
@@ -71,6 +64,8 @@ function candidateRangeFrom(input: {
   reportedTime: string | null;
   source: string;
   period: unknown;
+  windowStart: string | null;
+  windowEnd: string | null;
   uncertaintyBefore: number | null;
   uncertaintyAfter: number | null;
 }): AgenticRectificationContext["candidateRange"] {
@@ -88,16 +83,14 @@ function candidateRangeFrom(input: {
       end_time: shiftedTime(referenceTime, input.uncertaintyAfter ?? fallback),
     };
   }
-  if (input.source === "period_only" || input.source === "legacy_import") {
-    const period = typeof input.period === "string"
-      ? periodRanges[input.period as keyof typeof periodRanges]
-      : null;
-    if (period) return period;
-    if (input.source === "period_only") throw new AgenticRectificationProfileError("missing_birth_time_period");
-  }
-  if (input.source === "unknown" || input.source === "legacy_import") {
-    return { start_time: "00:00", end_time: "23:59" };
-  }
+  const range = declaredClockRange({
+    source: input.source,
+    period: typeof input.period === "string" ? input.period : null,
+    startTime: input.windowStart,
+    endTime: input.windowEnd,
+  });
+  if (range) return { start_time: range.startTime, end_time: range.endTime };
+  if (input.source === "period_only") throw new AgenticRectificationProfileError("missing_birth_time_period");
   throw new AgenticRectificationProfileError("missing_birth_time");
 }
 
@@ -173,7 +166,7 @@ export async function loadAgenticRectificationProfile(
 ): Promise<AgenticRectificationProfile> {
   const { data, error } = await accounting
     .from("profiles")
-    .select("birth_date,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,uncertainty_before_minutes,uncertainty_after_minutes,latitude,longitude,timezone_offset")
+    .select("birth_date,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,declared_window_start,declared_window_end,uncertainty_before_minutes,uncertainty_after_minutes,latitude,longitude,timezone_offset")
     .eq("id", userId)
     .single();
   if (error || !data) throw new AgenticRectificationProfileError("profile_unavailable");
@@ -198,6 +191,8 @@ export async function loadAgenticRectificationProfile(
       reportedTime,
       source: rawSource,
       period: data.birth_time_period,
+      windowStart: timeValue(data.declared_window_start),
+      windowEnd: timeValue(data.declared_window_end),
       uncertaintyBefore,
       uncertaintyAfter,
     }),
diff --git a/frontend/src/lib/rectification-agentic/v9/case-service.ts b/frontend/src/lib/rectification-agentic/v9/case-service.ts
index 23277ed7..5edf5f21 100644
--- a/frontend/src/lib/rectification-agentic/v9/case-service.ts
+++ b/frontend/src/lib/rectification-agentic/v9/case-service.ts
@@ -39,6 +39,8 @@ export type V9BaselineSnapshot = Readonly<{
   timezone_offset: number;
   birth_time_source: string;
   birth_time_period: string | null;
+  declared_window_start: string | null;
+  declared_window_end: string | null;
   reported_birth_time: string | null;
   active_birth_time: string | null;
   uncertainty_before_minutes: number | null;
@@ -119,6 +121,8 @@ function deriveCandidateRange(input: {
   reportedTime: string | null;
   source: string;
   period: string | null;
+  windowStart: string | null;
+  windowEnd: string | null;
 }): { start_time: string; end_time: string } {
   if (input.reportedTime) {
     return {
@@ -127,7 +131,12 @@ function deriveCandidateRange(input: {
     };
   }
 
-  const range = declaredClockRange({ source: input.source, period: input.period });
+  const range = declaredClockRange({
+    source: input.source,
+    period: input.period,
+    startTime: input.windowStart,
+    endTime: input.windowEnd,
+  });
   if (!range) throw new RectificationCaseServiceError("profile_incomplete");
   return { start_time: range.startTime, end_time: range.endTime };
 }
@@ -142,6 +151,8 @@ function baselineFingerprint(baseline: V9BaselineSnapshot): string {
     String(baseline.timezone_offset),
     baseline.birth_time_source,
     baseline.birth_time_period ?? "",
+    baseline.declared_window_start ?? "",
+    baseline.declared_window_end ?? "",
     baseline.reported_birth_time ?? "",
     baseline.active_birth_time ?? "",
     String(baseline.uncertainty_before_minutes ?? ""),
@@ -157,7 +168,7 @@ export async function loadV9RectificationProfile(
   const { data, error } = await accounting
     .from("profiles")
     .select(
-      "birth_date,birth_place_label,reported_birth_time,birth_time_source,birth_time_period,uncertainty_before_minutes,uncertainty_after_minutes,latitude,longitude,timezone_id,timezone_offset",
+      "birth_date,birth_place_label,reported_birth_time,birth_time_source,birth_time_period,declared_window_start,declared_window_end,uncertainty_before_minutes,uncertainty_after_minutes,latitude,longitude,timezone_id,timezone_offset",
     )
     .eq("id", userId)
     .single();
@@ -179,6 +190,8 @@ export async function loadV9RectificationProfile(
   const source = typeof row.birth_time_source === "string" ? row.birth_time_source.trim() : "";
   const reportedTime = timeValue(row.reported_birth_time);
   const period = typeof row.birth_time_period === "string" ? row.birth_time_period : null;
+  const windowStart = timeValue(row.declared_window_start);
+  const windowEnd = timeValue(row.declared_window_end);
   const uncertaintyBefore = numberOrNull(row.uncertainty_before_minutes);
   const uncertaintyAfter = numberOrNull(row.uncertainty_after_minutes);
   if (!birthDate || !birthPlaceLabel || latitude === null || longitude === null || !timezoneId || timezoneOffset === null || !source) {
@@ -194,6 +207,8 @@ export async function loadV9RectificationProfile(
     timezone_offset: timezoneOffset,
     birth_time_source: source,
     birth_time_period: period,
+    declared_window_start: windowStart,
+    declared_window_end: windowEnd,
     reported_birth_time: reportedTime,
     // A fresh Case must never inherit an accepted/active minute as its new baseline.
     active_birth_time: null,
@@ -205,7 +220,13 @@ export async function loadV9RectificationProfile(
     userId,
     baseline,
     baselineFingerprint: baselineFingerprint(baseline),
-    candidateRange: deriveCandidateRange({ reportedTime, source, period }),
+    candidateRange: deriveCandidateRange({
+      reportedTime,
+      source,
+      period,
+      windowStart,
+      windowEnd,
+    }),
   };
 }
 
diff --git a/frontend/supabase/migrations/20260822010000_declared_birth_window_clocks.sql b/frontend/supabase/migrations/20260822010000_declared_birth_window_clocks.sql
new file mode 100644
index 00000000..32036e62
--- /dev/null
+++ b/frontend/supabase/migrations/20260822010000_declared_birth_window_clocks.sql
@@ -0,0 +1,62 @@
+begin;
+
+-- BUG-353: period_only declarations are a start/end clock window, not a
+-- coarse bucket plus free-text clue. Rectification and window consultation
+-- read these columns; birth_time_period remains a legacy fallback.
+
+alter table public.profiles
+  add column if not exists declared_window_start text,
+  add column if not exists declared_window_end text;
+
+alter table public.profiles
+  drop constraint if exists profiles_declared_window_clocks;
+
+alter table public.profiles
+  add constraint profiles_declared_window_clocks check (
+    (declared_window_start is null and declared_window_end is null)
+    or (
+      declared_window_start ~ '^([01][0-9]|2[0-3]):[0-5][0-9]$'
+      and declared_window_end ~ '^([01][0-9]|2[0-3]):[0-5][0-9]$'
+      and declared_window_start is distinct from declared_window_end
+    )
+  );
+
+update public.profiles
+set
+  declared_window_start = case birth_time_period
+    when 'early_morning' then '04:00'
+    when 'morning' then '08:00'
+    when 'afternoon' then '12:00'
+    when 'evening' then '18:00'
+    when 'late_night' then '23:00'
+    else declared_window_start
+  end,
+  declared_window_end = case birth_time_period
+    when 'early_morning' then '07:59'
+    when 'morning' then '11:59'
+    when 'afternoon' then '17:59'
+    when 'evening' then '22:59'
+    when 'late_night' then '03:59'
+    else declared_window_end
+  end
+where birth_time_source = 'period_only'
+  and declared_window_start is null
+  and declared_window_end is null
+  and birth_time_period in ('early_morning', 'morning', 'afternoon', 'evening', 'late_night');
+
+grant select (
+  declared_window_start,
+  declared_window_end
+) on table public.profiles to service_role;
+
+grant insert (
+  declared_window_start,
+  declared_window_end
+) on table public.profiles to service_role;
+
+grant update (
+  declared_window_start,
+  declared_window_end
+) on table public.profiles to service_role;
+
+commit;
diff --git a/frontend/tests/account-api.test.ts b/frontend/tests/account-api.test.ts
index 05221274..dd94cd7d 100644
--- a/frontend/tests/account-api.test.ts
+++ b/frontend/tests/account-api.test.ts
@@ -100,6 +100,34 @@ test("profile patch schema validates calendar, clock, source requirements, and l
     uncertainty_before_minutes: null,
     uncertainty_after_minutes: null,
   }).success, false);
+  assert.equal(accountProfilePatchSchema.safeParse({
+    ...valid,
+    reported_birth_time: null,
+    birth_time_source: "period_only",
+    birth_time_period: "evening",
+    uncertainty_before_minutes: null,
+    uncertainty_after_minutes: null,
+  }).success, true);
+  assert.equal(accountProfilePatchSchema.safeParse({
+    ...valid,
+    reported_birth_time: null,
+    birth_time_source: "period_only",
+    birth_time_period: null,
+    declared_window_start: "14:30",
+    declared_window_end: "15:00",
+    uncertainty_before_minutes: null,
+    uncertainty_after_minutes: null,
+  }).success, true);
+  assert.equal(accountProfilePatchSchema.safeParse({
+    ...valid,
+    reported_birth_time: null,
+    birth_time_source: "period_only",
+    birth_time_period: null,
+    declared_window_start: "14:30",
+    declared_window_end: "14:30",
+    uncertainty_before_minutes: null,
+    uncertainty_after_minutes: null,
+  }).success, false);
   assert.equal(accountProfilePatchSchema.safeParse({
     ...valid,
     reported_birth_time: null,
diff --git a/frontend/tests/birth-time-consultation-consent.test.ts b/frontend/tests/birth-time-consultation-consent.test.ts
index 20d1dc04..a145016c 100644
--- a/frontend/tests/birth-time-consultation-consent.test.ts
+++ b/frontend/tests/birth-time-consultation-consent.test.ts
@@ -23,6 +23,8 @@ const reportedExactTime = {
   reportedTime: "05:30",
   birthTimeSource: "family_exact",
   birthTimePeriod: "",
+  declaredWindowStart: "",
+  declaredWindowEnd: "",
   birthTimeClue: "",
   uncertaintyBeforeMinutes: 10,
   uncertaintyAfterMinutes: 10,
@@ -214,11 +216,13 @@ test("birth time intake starts with exact or uncertain choices and keeps rectifi
   assert.match(model, /我不确定准确时间/);
   assert.match(intake, /你对出生时间了解多少？/);
   assert.match(intake, /不用猜具体分钟/);
-  assert.match(intake, /aria-label="选择出生时间"/);
+  assert.match(intake, /aria-label=\{ariaLabel\}/);
+  assert.match(intake, /ariaLabel = "选择出生时间"/);
   assert.doesNotMatch(intake, /source === "family_exact" \|\| source === "approximate"/);
-  assert.match(intake, /请选择最接近的时间范围/);
+  assert.match(intake, /选择你记得的开始和结束时间/);
   assert.match(intake, /完全不清楚，跳过出生时间/);
   assert.match(intake, /生时校正以后需要时再做/);
+  assert.doesNotMatch(intake, /请选择最接近的时间范围|补充描述/);
 });
 
 test("homepage and profile result copy use the source-aware consultation options", () => {
diff --git a/frontend/tests/birth-time-intake.test.ts b/frontend/tests/birth-time-intake.test.ts
index b5948ba8..51c18372 100644
--- a/frontend/tests/birth-time-intake.test.ts
+++ b/frontend/tests/birth-time-intake.test.ts
@@ -26,6 +26,8 @@ const emptyDraft: BirthTimeDraft = {
   reportedTime: "",
   birthTimeSource: "",
   birthTimePeriod: "",
+  declaredWindowStart: "",
+  declaredWindowEnd: "",
   birthTimeClue: "",
   uncertaintyBeforeMinutes: null,
   uncertaintyAfterMinutes: null,
@@ -45,6 +47,12 @@ test("birth time intake requires only the fields selected by the source", () =>
     birthTimeSource: "period_only",
     birthTimePeriod: "evening",
   } satisfies BirthTimeDraft;
+  const customWindow = {
+    ...emptyDraft,
+    birthTimeSource: "period_only",
+    declaredWindowStart: "14:30",
+    declaredWindowEnd: "15:00",
+  } satisfies BirthTimeDraft;
   const incompleteApproximate = {
     ...emptyDraft,
     birthTimeSource: "approximate",
@@ -53,6 +61,11 @@ test("birth time intake requires only the fields selected by the source", () =>
 
   assert.equal(isBirthTimeDraftReady(hospital), true);
   assert.equal(isBirthTimeDraftReady(period), true);
+  assert.equal(isBirthTimeDraftReady(customWindow), true);
+  assert.equal(isBirthTimeDraftReady({
+    ...customWindow,
+    declaredWindowEnd: "14:30",
+  }), false);
   assert.equal(isBirthTimeDraftReady(incompleteApproximate), true);
   assert.equal(isBirthTimeDraftReady({ ...emptyDraft, birthTimeSource: "unknown" }), true);
 });
@@ -60,6 +73,8 @@ test("birth time intake requires only the fields selected by the source", () =>
 test("family exact intake defaults and persists as reported 0/0 without engine confirmation", () => {
   assert.deepEqual(birthTimeSourceDefaults.family_exact, {
     birthTimePeriod: "",
+    declaredWindowStart: "",
+    declaredWindowEnd: "",
     birthTimeClue: "",
     uncertaintyBeforeMinutes: 0,
     uncertaintyAfterMinutes: 0,
@@ -80,6 +95,8 @@ test("family exact intake defaults and persists as reported 0/0 without engine c
     reported_birth_time: "05:00",
     birth_time_source: "family_exact",
     birth_time_period: null,
+    declared_window_start: null,
+    declared_window_end: null,
     birth_time_clue: null,
     uncertainty_before_minutes: 0,
     uncertainty_after_minutes: 0,
@@ -240,11 +257,11 @@ test("a persisted candidate working time takes precedence over the reported rang
   // When: a profile surface asks what birth-time state to display.
   const display = birthTimeDisplayState(candidate);
 
-  // Then: the candidate minute is primary and the original period remains secondary.
+  // Then: the candidate minute is primary and the original clock window remains secondary.
   assert.deepEqual(display, {
     kind: "candidate",
     activeTime: "04:53",
-    reportedLabel: "凌晨 / 清晨（04:00—07:59）",
+    reportedLabel: "04:00—07:59",
   });
 });
 
@@ -263,6 +280,8 @@ test("birth time declaration payload cannot write deterministic application fiel
     reported_birth_time: "14:30",
     birth_time_source: "approximate",
     birth_time_period: null,
+    declared_window_start: null,
+    declared_window_end: null,
     birth_time_clue: null,
     uncertainty_before_minutes: 30,
     uncertainty_after_minutes: 30,
@@ -279,6 +298,23 @@ test("birth time intake describes uncertainty without claiming false precision",
   } satisfies BirthTimeDraft;
 
   assert.equal(describeBirthTimeDraft(approximate), "1993年4月17日，约 14:30");
+  assert.equal(
+    describeBirthTimeDraft({
+      ...emptyDraft,
+      birthTimeSource: "period_only",
+      declaredWindowStart: "14:30",
+      declaredWindowEnd: "15:00",
+    }),
+    "1993年4月17日，14:30—15:00",
+  );
+  assert.equal(
+    describeBirthTimeDraft({
+      ...emptyDraft,
+      birthTimeSource: "period_only",
+      birthTimePeriod: "evening",
+    }),
+    "1993年4月17日，18:00—22:59",
+  );
   assert.equal(
     assistantIntentCopy("present_saved_candidate_range"),
     "目前只能保存候选范围，还没有足够证据应用到具体分钟。",
@@ -317,7 +353,7 @@ test("fresh intake copy stays user-facing and explains the next missing field",
   );
   assert.equal(
     birthTimeSourceOptions.find((option) => option.value === "period_only")?.hint,
-    "只知道大概几点、上午下午，或完全不清楚",
+    "选择一段开始到结束的时间，或完全不清楚",
   );
   assert.equal(birthTimeSourceOptions.every((option) => !/引擎确认|初始化填报/.test(option.hint)), true);
   assert.equal(birthTimeDraftReadyHint({ ...emptyDraft, date: "" }), "请先选择出生日期");
@@ -331,7 +367,13 @@ test("fresh intake copy stays user-facing and explains the next missing field",
   assert.equal(birthTimeDraftReadyHint({
     ...emptyDraft,
     birthTimeSource: "period_only",
-  }), "请选择一个大致时段");
+  }), "请选择开始和结束时间");
+  assert.equal(birthTimeDraftReadyHint({
+    ...emptyDraft,
+    birthTimeSource: "period_only",
+    declaredWindowStart: "14:30",
+    declaredWindowEnd: "14:30",
+  }), "开始和结束不能是同一分钟");
 });
 
 test("fresh intake preserves exact, approximate-period, and unknown-time paths without auto-confirming", () => {
@@ -343,15 +385,38 @@ test("fresh intake preserves exact, approximate-period, and unknown-time paths w
     ["family_exact", "period_only"],
   );
   assert.doesNotMatch(source, /已用于当前排盘/);
-  assert.match(source, /birthTimePeriodOptions/);
+  assert.doesNotMatch(source, /birthTimePeriodOptions/);
   assert.match(source, /birthTimeSource: "unknown"/);
-  assert.match(source, /请选择最接近的时间范围/);
+  assert.match(source, /选择你记得的开始和结束时间/);
   assert.match(source, /完全不清楚，跳过出生时间/);
-  assert.match(source, /我可以描述一个时间范围/);
+  assert.match(source, /我可以选一段时间范围/);
+  assert.doesNotMatch(source, /补充描述|请选择最接近的时间范围|我可以描述一个时间范围/);
   assert.match(source, /birthTimeStatus: "reported"/);
   assert.match(source, /birthTimeConsultationOptionsCopy\(value\)/);
 });
 
+test("a custom clock window persists as the scan bounds without a leftover period bucket", () => {
+  const draft = {
+    ...emptyDraft,
+    birthTimeSource: "period_only",
+    birthTimePeriod: "afternoon",
+    declaredWindowStart: "14:30",
+    declaredWindowEnd: "15:00",
+    birthTimeStatus: "reported",
+  } satisfies BirthTimeDraft;
+
+  assert.deepEqual(birthTimePersistenceValues(draft), {
+    reported_birth_time: null,
+    birth_time_source: "period_only",
+    birth_time_period: null,
+    declared_window_start: "14:30",
+    declared_window_end: "15:00",
+    birth_time_clue: null,
+    uncertainty_before_minutes: null,
+    uncertainty_after_minutes: null,
+  });
+});
+
 test("a saved declaration adopts the birth-time truth the account write returned", () => {
   const exactDeclaration = {
     ...emptyDraft,
diff --git a/frontend/tests/consultation-route-service.test.ts b/frontend/tests/consultation-route-service.test.ts
index 24e3f618..2a4259b7 100644
--- a/frontend/tests/consultation-route-service.test.ts
+++ b/frontend/tests/consultation-route-service.test.ts
@@ -323,9 +323,31 @@ test("stale general mode upgrades period-only profiles to a declared birth windo
   assert.equal(prepared.reservation, "reserved");
 });
 
+test("a custom declared window consults those clocks instead of the leftover period bucket", async () => {
+  const prepared = await prepareConsultationRoute({
+    userId: "user-1",
+    mode: "general_no_birth_time",
+    loadProfile: async () => ({
+      ...profile,
+      reported_birth_time: null,
+      active_birth_time: null,
+      birth_time_source: "period_only",
+      birth_time_period: "afternoon",
+      declared_window_start: "14:30",
+      declared_window_end: "15:00",
+      birth_time_status: "reported",
+    }),
+    reserve: async () => "reserved",
+  });
+
+  assert.equal(prepared.consultationMode, "declared_birth_window");
+  assert.equal(prepared.declaredWindow?.toolInput.rangeStart, "14:30");
+  assert.equal(prepared.declaredWindow?.toolInput.rangeEnd, "15:00");
+});
+
 test("consult route constructs workflow input from the route service rather than client chart fields", () => {
   const route = readFileSync(new URL("../src/app/api/consult/route.ts", import.meta.url), "utf8");
-  const select = "name,birth_date,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,birth_time_status,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset";
+  const select = "name,birth_date,reported_birth_time,active_birth_time,birth_time_source,birth_time_period,declared_window_start,declared_window_end,birth_time_status,country_code,province_code,city_code,district_code,latitude,longitude,timezone_offset";
 
   assert.match(route, new RegExp(select));
   assert.match(route, /prepareConsultationRoute/);
diff --git a/frontend/tests/database-local-business.test.ts b/frontend/tests/database-local-business.test.ts
index 26cd94bd..4cf5a818 100644
--- a/frontend/tests/database-local-business.test.ts
+++ b/frontend/tests/database-local-business.test.ts
@@ -79,6 +79,7 @@ test("local PostgreSQL applies the reviewed business schema and serves authentic
     assert.match(migration.stdout, /applied 20260816010000_accept_exact_family_birth_times\.sql/);
     assert.match(migration.stdout, /applied 20260818010000_admin_product_catalog_mutations\.sql/);
     assert.match(migration.stdout, /applied 20260819010000_rectification_ingest_precision_plateau\.sql/);
+    assert.match(migration.stdout, /applied 20260822010000_declared_birth_window_clocks\.sql/);
 
     assert.equal(
       fixture.psql(`
diff --git a/frontend/tests/declared-birth-window.test.ts b/frontend/tests/declared-birth-window.test.ts
index 4ae3a8c5..382ab991 100644
--- a/frontend/tests/declared-birth-window.test.ts
+++ b/frontend/tests/declared-birth-window.test.ts
@@ -4,7 +4,9 @@ import test from "node:test";
 import {
   DECLARED_PERIOD_RANGES,
   declaredClockRange,
+  declaredClockRangeFromProfile,
   declaredWindowProbeClocks,
+  matchingDeclaredPeriod,
 } from "../src/lib/declared-birth-window.ts";
 
 test("evening probes stay inside the declared range and are not the midpoint", () => {
@@ -34,3 +36,52 @@ test("period_only without a period cannot invent a clock range", () => {
     DECLARED_PERIOD_RANGES.evening,
   );
 });
+
+test("a custom start and end clock beats a leftover afternoon bucket", () => {
+  assert.deepEqual(
+    declaredClockRange({
+      source: "period_only",
+      period: "afternoon",
+      startTime: "14:30",
+      endTime: "15:00",
+    }),
+    { label: "14:30—15:00", startTime: "14:30", endTime: "15:00" },
+  );
+  assert.equal(matchingDeclaredPeriod("14:30", "15:00"), null);
+  assert.equal(matchingDeclaredPeriod("12:00", "17:59"), "afternoon");
+  assert.equal(
+    declaredClockRange({
+      source: "period_only",
+      startTime: "14:30",
+      endTime: "14:30",
+    }),
+    null,
+  );
+  assert.deepEqual(
+    declaredClockRange({
+      source: "period_only",
+      startTime: "23:00",
+      endTime: "03:59",
+    }),
+    { label: "23:00—03:59", startTime: "23:00", endTime: "03:59" },
+  );
+});
+
+test("profile readers prefer declared window clocks over the period bucket", () => {
+  assert.deepEqual(
+    declaredClockRangeFromProfile({
+      birth_time_source: "period_only",
+      birth_time_period: "afternoon",
+      declared_window_start: "14:30",
+      declared_window_end: "15:00",
+    }),
+    { label: "14:30—15:00", startTime: "14:30", endTime: "15:00" },
+  );
+  assert.deepEqual(
+    declaredClockRangeFromProfile({
+      birthTimeSource: "period_only",
+      birthTimePeriod: "evening",
+    }),
+    DECLARED_PERIOD_RANGES.evening,
+  );
+});
diff --git a/frontend/tests/onboarding-cache-policy.test.ts b/frontend/tests/onboarding-cache-policy.test.ts
index a2747c61..16a778c7 100644
--- a/frontend/tests/onboarding-cache-policy.test.ts
+++ b/frontend/tests/onboarding-cache-policy.test.ts
@@ -77,11 +77,16 @@ test("period-only declaration fields participate in the onboarding cache identit
     uncertaintyAfterMinutes: null,
   };
   const morning = { ...earlyMorning, birthTimePeriod: "morning" };
+  const customWindow = { ...earlyMorning, declaredWindowStart: "14:30", declaredWindowEnd: "15:00" };
 
   assert.notEqual(
     createOnboardingCacheIdentity(earlyMorning).readyVersion,
     createOnboardingCacheIdentity(morning).readyVersion,
   );
+  assert.notEqual(
+    createOnboardingCacheIdentity(earlyMorning).readyVersion,
+    createOnboardingCacheIdentity(customWindow).readyVersion,
+  );
 });
 
 test("current profile accepts only valid ready content and an active current pending claim", () => {
diff --git a/frontend/tests/onboarding-presentation.test.ts b/frontend/tests/onboarding-presentation.test.ts
index 5534ede0..20eceadf 100644
--- a/frontend/tests/onboarding-presentation.test.ts
+++ b/frontend/tests/onboarding-presentation.test.ts
@@ -12,7 +12,7 @@ import {
 
 const completeProfile = {
   name: "林遥", date: "1990-06-15", time: "12:30", reportedTime: "12:30",
-  birthTimeSource: "hospital_record", birthTimePeriod: "", birthTimeClue: "出生证明", birthTimeStatus: "confirmed",
+  birthTimeSource: "hospital_record", birthTimePeriod: "", declaredWindowStart: "", declaredWindowEnd: "", birthTimeClue: "出生证明", birthTimeStatus: "confirmed",
   uncertaintyBeforeMinutes: 0, uncertaintyAfterMinutes: 0, rectificationCaseId: "", countryCode: "CN", provinceCode: "110000", cityCode: "110000-city", districtCode: "110101",
 } as const;
 
diff --git a/frontend/tests/onboarding-route-fake.ts b/frontend/tests/onboarding-route-fake.ts
index 888f2deb..726f8b41 100644
--- a/frontend/tests/onboarding-route-fake.ts
+++ b/frontend/tests/onboarding-route-fake.ts
@@ -78,6 +78,8 @@ export function completeProfileRow(
     active_birth_time: "12:30",
     birth_time_source: "legacy_import",
     birth_time_period: null,
+    declared_window_start: null,
+    declared_window_end: null,
     birth_time_clue: null,
     uncertainty_before_minutes: null,
     uncertainty_after_minutes: null,
diff --git a/frontend/tests/personal-report-entry.test.ts b/frontend/tests/personal-report-entry.test.ts
index bbddae8d..459a9943 100644
--- a/frontend/tests/personal-report-entry.test.ts
+++ b/frontend/tests/personal-report-entry.test.ts
@@ -224,6 +224,8 @@ test("accepted/confirmed remain the only statuses ready for verified natal consu
     reportedTime: "12:00",
     birthTimeSource: "family_exact" as const,
     birthTimePeriod: "morning" as const,
+    declaredWindowStart: "",
+    declaredWindowEnd: "",
     birthTimeClue: "",
     uncertaintyBeforeMinutes: 10,
     uncertaintyAfterMinutes: 10,
diff --git a/frontend/tests/profile-persistence.test.ts b/frontend/tests/profile-persistence.test.ts
index f87abbfc..0a45e321 100644
--- a/frontend/tests/profile-persistence.test.ts
+++ b/frontend/tests/profile-persistence.test.ts
@@ -1,5 +1,5 @@
 import assert from "node:assert/strict";
-import { readFileSync } from "node:fs";
+import { existsSync, readFileSync } from "node:fs";
 import test from "node:test";
 
 test("upserts a missing profile when saving account details", () => {
@@ -46,6 +46,8 @@ test("account route persists the birth-time declaration before assessment", () =
     "reported_birth_time",
     "birth_time_source",
     "birth_time_period",
+    "declared_window_start",
+    "declared_window_end",
     "birth_time_clue",
     "uncertainty_before_minutes",
     "uncertainty_after_minutes",
@@ -113,3 +115,27 @@ test("reported birth declarations remain editable and candidate times never over
   assert.match(migration, /update public\.profiles\s+set reported_birth_time\s*=\s*null[\s\S]*?birth_time_source\s+in\s*\(\s*'period_only'\s*,\s*'unknown'\s*\)/i);
   assert.match(migration, /profiles_reported_birth_time_source_consistency/i);
 });
+
+test("declared birth windows persist as start and end clocks with service-role grants", () => {
+  const migration = readFileSync(
+    new URL(
+      "../supabase/migrations/20260822010000_declared_birth_window_clocks.sql",
+      import.meta.url,
+    ),
+    "utf8",
+  );
+
+  assert.match(migration, /add column if not exists declared_window_start text/);
+  assert.match(migration, /add column if not exists declared_window_end text/);
+  assert.match(migration, /profiles_declared_window_clocks/);
+  assert.match(migration, /birth_time_source = 'period_only'/);
+  assert.match(migration, /when 'afternoon' then '12:00'/);
+  assert.match(migration, /when 'afternoon' then '17:59'/);
+  assert.match(migration, /grant select \(\s*declared_window_start,\s*declared_window_end\s*\)/i);
+  assert.match(migration, /grant insert \(\s*declared_window_start,\s*declared_window_end\s*\)/i);
+  assert.match(migration, /grant update \(\s*declared_window_start,\s*declared_window_end\s*\)/i);
+  assert.equal(
+    existsSync(new URL("../db/migrations/20260822010000_declared_birth_window_clocks.sql", import.meta.url)),
+    false,
+  );
+});
diff --git a/frontend/tests/rectification-agentic-session.test.ts b/frontend/tests/rectification-agentic-session.test.ts
index a63980c7..5cf234a3 100644
--- a/frontend/tests/rectification-agentic-session.test.ts
+++ b/frontend/tests/rectification-agentic-session.test.ts
@@ -110,6 +110,19 @@ test("loadAgenticRectificationProfile accepts a period-only declaration without
   assert.equal(profile.baselineBirthTimePeriod, "late_night");
 });
 
+test("loadAgenticRectificationProfile uses a custom declared window instead of the leftover period", async () => {
+  const { client } = fakeAccounting(fakeProfileRow({
+    reported_birth_time: null,
+    active_birth_time: null,
+    birth_time_source: "period_only",
+    birth_time_period: "afternoon",
+    declared_window_start: "14:30",
+    declared_window_end: "15:00",
+  }));
+  const profile = await loadAgenticRectificationProfile(client as never, userId);
+  assert.deepEqual(profile.candidateRange, { start_time: "14:30", end_time: "15:00" });
+});
+
 test("loadAgenticRectificationProfile accepts an unknown time as the full day", async () => {
   const { client } = fakeAccounting(fakeProfileRow({
     reported_birth_time: null,
diff --git a/frontend/tests/rectification-v9-case-service.test.ts b/frontend/tests/rectification-v9-case-service.test.ts
index b88f0b85..dbc67df9 100644
--- a/frontend/tests/rectification-v9-case-service.test.ts
+++ b/frontend/tests/rectification-v9-case-service.test.ts
@@ -168,6 +168,77 @@ test("period-only profiles open with their selected server-owned range", async (
   }
 });
 
+test("a custom declared window opens the Case with those clocks, not the leftover afternoon bucket", async () => {
+  const capturedArgs: { value: Record<string, unknown> | null } = { value: null };
+  const accounting = fakeAccounting({
+    profile: {
+      ...completeProfile,
+      reported_birth_time: null,
+      birth_time_source: "period_only",
+      birth_time_period: "afternoon",
+      declared_window_start: "14:30",
+      declared_window_end: "15:00",
+    },
+    rpc: async (_fn, args) => {
+      capturedArgs.value = args;
+      return {
+        data: {
+          disposition: "created",
+          case_id: caseId,
+          session_id: sessionId,
+          status: "draft",
+          should_start_opening: true,
+          skill_version: "9.0.0",
+        },
+        error: null,
+      };
+    },
+  });
+
+  const response = await openRectificationCase(accounting, "user-1", {
+    intent: "homepage",
+    requestId,
+  });
+
+  assert.equal(response.disposition, "created");
+  assert.deepEqual(capturedArgs.value?.p_candidate_range, { start_time: "14:30", end_time: "15:00" });
+  assert.equal(
+    (capturedArgs.value?.p_baseline_birth_snapshot as Record<string, unknown>).declared_window_start,
+    "14:30",
+  );
+  assert.equal(
+    (capturedArgs.value?.p_baseline_birth_snapshot as Record<string, unknown>).declared_window_end,
+    "15:00",
+  );
+});
+
+test("tightening a declared window changes the Case fingerprint", async () => {
+  const afternoon = await loadV9RectificationProfile(fakeAccounting({
+    profile: {
+      ...completeProfile,
+      reported_birth_time: null,
+      birth_time_source: "period_only",
+      birth_time_period: "afternoon",
+      declared_window_start: "12:00",
+      declared_window_end: "17:59",
+    },
+  }), "user-1");
+  const tight = await loadV9RectificationProfile(fakeAccounting({
+    profile: {
+      ...completeProfile,
+      reported_birth_time: null,
+      birth_time_source: "period_only",
+      birth_time_period: "afternoon",
+      declared_window_start: "14:30",
+      declared_window_end: "15:00",
+    },
+  }), "user-1");
+
+  assert.notEqual(afternoon.baselineFingerprint, tight.baselineFingerprint);
+  assert.deepEqual(afternoon.candidateRange, { start_time: "12:00", end_time: "17:59" });
+  assert.deepEqual(tight.candidateRange, { start_time: "14:30", end_time: "15:00" });
+});
+
 test("period-only profiles with an IANA timezone can open when the cached offset is missing", async () => {
   const originalFetch = globalThis.fetch;
   const capturedArgs: { value: Record<string, unknown> | null } = { value: null };
@@ -333,6 +404,8 @@ test("homepage and new opens ignore active time and legacy uncertainty for their
       timezone_offset: 8,
       birth_time_source: "family_exact",
       birth_time_period: null,
+      declared_window_start: null,
+      declared_window_end: null,
       reported_birth_time: "05:00",
       active_birth_time: null,
       uncertainty_before_minutes: 10,