diff --git a/packages/contracts/src/api/episode-mapping.ts b/packages/contracts/src/api/episode-mapping.ts
index d7866091..785e1310 100644
--- a/packages/contracts/src/api/episode-mapping.ts
+++ b/packages/contracts/src/api/episode-mapping.ts
@@ -51,4 +51,33 @@ export const episodeMappingApi = {
       response: em.EpisodeMappingPreview,
     }),
   },
+  episodeGroups: {
+    list: ep({
+      method: "get",
+      path: "/media-entities/{id}/episode-groups",
+      scope: "read",
+      summary: "作品可选的季集结构：TMDB 剧集组列表与当前选择",
+      params: IdParam,
+      response: em.EpisodeGroupList,
+    }),
+    seasons: ep({
+      method: "get",
+      path: "/media-entities/{id}/episode-structure",
+      scope: "read",
+      summary: "某套季集结构（TMDB 默认季或剧集组）的季卡片与每集，带本地已入库情况（纯读）",
+      params: IdParam,
+      query: em.EpisodeStructureQuery,
+      response: em.EpisodeStructureSeasons,
+    }),
+    set: ep({
+      method: "put",
+      path: "/media-entities/{id}/episode-group",
+      scope: "organize.execute",
+      summary:
+        "切换作品的季集结构：按 TMDB 原季集原地迁移集单元（引用不动），重建季表，按作品重算已绑定资源并刷新元数据",
+      params: IdParam,
+      body: em.EpisodeGroupSetInput,
+      response: em.EpisodeGroupSetResult,
+    }),
+  },
 } as const;
diff --git a/packages/contracts/src/content.ts b/packages/contracts/src/content.ts
index 8b6663c3..473b985f 100644
--- a/packages/contracts/src/content.ts
+++ b/packages/contracts/src/content.ts
@@ -25,6 +25,11 @@ export const MediaEntity = EntityBase.extend({
   lastMetadataRefreshAt: Timestamp.nullable(),
   /** 作品级命名模板覆盖 {movie?, tv?, variety?}(见 settings NamingOverride);null = 不覆盖。经 PUT /media-entities/{id}/naming-override 修改 */
   namingOverride: JsonObject.nullable().optional(),
+  /** 季集结构:TMDB 剧集组 id / 名称;null = TMDB 默认季。经 PUT /media-entities/{id}/episode-group 修改 */
+  episodeGroupId: z.string().nullable().optional(),
+  episodeGroupName: z.string().nullable().optional(),
+  episodeGroupSetAt: Timestamp.nullable().optional(),
+  episodeGroupSetBy: z.string().nullable().optional(),
 });
 export type MediaEntity = z.infer<typeof MediaEntity>;
 export const MediaEntityCreate = MediaEntity.pick({
diff --git a/packages/contracts/src/episode-mapping.ts b/packages/contracts/src/episode-mapping.ts
index fae62220..442c6ac2 100644
--- a/packages/contracts/src/episode-mapping.ts
+++ b/packages/contracts/src/episode-mapping.ts
@@ -51,6 +51,7 @@ export const EpisodeResolutionMethod = z.enum([
   "absolute_in_season",
   "absolute_cross_season",
   "air_date",
+  "tmdb_season",
   "unverified",
   "unresolved",
   "skipped",
@@ -197,6 +198,8 @@ export const EpisodeSeasonSummary = z.object({
   ),
   latestSeason: z.number().int().nullable(),
   ended: z.boolean(),
+  /** 季表来自哪套季集结构:null = TMDB 默认季;否则为作品选的剧集组 */
+  structure: z.object({ groupId: z.string(), name: z.string() }).nullable().optional(),
 });
 export type EpisodeSeasonSummary = z.infer<typeof EpisodeSeasonSummary>;
 
@@ -210,3 +213,119 @@ export const EpisodeMappingPreview = z.object({
   changed: z.number().int().min(0),
 });
 export type EpisodeMappingPreview = z.infer<typeof EpisodeMappingPreview>;
+
+// ── 剧集组(季集结构):作品可选 TMDB 默认季或某个剧集组,季表与季 / 集单元随之生成 ──
+
+export const EpisodeGroupSummary = z.object({
+  id: z.string(),
+  name: z.string(),
+  /** TMDB type 1–7;未知为 null */
+  type: z.number().int().nullable(),
+  /** 类型的中文名(原始播出 / 绝对集号 / DVD / 数字发行 / 故事线 / 制作季 / 电视) */
+  typeLabel: z.string().nullable(),
+  description: z.string().nullable(),
+  /** 组(= 季)数 */
+  groupCount: z.number().int().min(0),
+  episodeCount: z.number().int().min(0),
+  network: z.string().nullable(),
+});
+export type EpisodeGroupSummary = z.infer<typeof EpisodeGroupSummary>;
+
+/** 作品当前的季集结构;null = TMDB 默认季 */
+export const EpisodeStructureCurrent = z.object({
+  groupId: z.string(),
+  name: z.string(),
+  setAt: z.string().nullable(),
+  /** `<actor_type>:<actor_id>` */
+  setBy: z.string().nullable(),
+});
+export type EpisodeStructureCurrent = z.infer<typeof EpisodeStructureCurrent>;
+
+export const EpisodeGroupList = z.object({
+  /** 作品是否能选剧集组(剧集 / 综艺且有 TMDB 剧集身份) */
+  applicable: z.boolean(),
+  current: EpisodeStructureCurrent.nullable(),
+  groups: z.array(EpisodeGroupSummary),
+  /** 取列表失败的原因码(TMDB 未配置 / 不可用);成功为 null */
+  error: z.string().nullable(),
+});
+export type EpisodeGroupList = z.infer<typeof EpisodeGroupList>;
+
+export const EpisodeStructureEpisode = z.object({
+  episodeNumber: z.number().int(),
+  name: z.string().nullable(),
+  airDate: z.string().nullable(),
+  /** TMDB 默认季集号(剧集组里才有意义;默认季时与自身相同) */
+  tmdbSeason: z.number().int(),
+  tmdbEpisode: z.number().int(),
+  /** 本地已入库(按 TMDB 原季集对照,换结构前也能看) */
+  inLibrary: z.boolean(),
+});
+export type EpisodeStructureEpisode = z.infer<typeof EpisodeStructureEpisode>;
+
+export const EpisodeStructureSeason = z.object({
+  seasonNumber: z.number().int(),
+  name: z.string().nullable(),
+  episodeCount: z.number().int().min(0),
+  /** 首播日期 */
+  airDate: z.string().nullable(),
+  posterPath: z.string().nullable(),
+  /** 本地已入库集数 */
+  inLibrary: z.number().int().min(0),
+  /** 当前结构下对应的季单元(选季订阅用);不是当前结构或还没建为 null */
+  seasonUnitId: Id.nullable(),
+  episodes: z.array(EpisodeStructureEpisode),
+});
+export type EpisodeStructureSeason = z.infer<typeof EpisodeStructureSeason>;
+
+/** 某套季集结构的季卡片(TMDB 默认季或某个剧集组),带本地已入库情况 */
+export const EpisodeStructureSeasons = z.object({
+  groupId: z.string().nullable(),
+  name: z.string(),
+  /** 是不是作品当前的季集结构 */
+  current: z.boolean(),
+  seasons: z.array(EpisodeStructureSeason),
+});
+export type EpisodeStructureSeasons = z.infer<typeof EpisodeStructureSeasons>;
+
+export const EpisodeStructureQuery = z.object({
+  /** 剧集组 id;不填 = TMDB 默认季 */
+  groupId: z.string().trim().min(1).max(64).optional(),
+});
+export type EpisodeStructureQuery = z.infer<typeof EpisodeStructureQuery>;
+
+export const EpisodeGroupSetInput = z.object({
+  /** 剧集组 id;null = 改回 TMDB 默认季 */
+  groupId: z.string().trim().min(1).max(64).nullable(),
+});
+export type EpisodeGroupSetInput = z.infer<typeof EpisodeGroupSetInput>;
+
+/** 切换时对不上的集单元(保留原号、标临时) */
+export const EpisodeGroupUnmatchedUnit = z.object({
+  unitId: Id,
+  seasonNumber: z.number().int().nullable(),
+  episodeNumber: z.number().int().nullable(),
+  /** no_origin:求不出 TMDB 原季集;not_in_target:目标结构里没有这一集;numbering_locked:编号已人工锁定 */
+  reason: z.enum(["no_origin", "not_in_target", "numbering_locked"]),
+  /** 有资产覆盖 / 资源 / 下载等引用 */
+  referenced: z.boolean(),
+});
+export type EpisodeGroupUnmatchedUnit = z.infer<typeof EpisodeGroupUnmatchedUnit>;
+
+export const EpisodeGroupSetResult = z.object({
+  changed: z.boolean(),
+  current: EpisodeStructureCurrent.nullable(),
+  /** 改了季集号的集单元数 */
+  moved: z.number().int().min(0),
+  /** 季集号不变的集单元数 */
+  kept: z.number().int().min(0),
+  unmatched: z.array(EpisodeGroupUnmatchedUnit),
+  /** 新结构的季与集数 */
+  seasons: z.array(z.object({ seasonNumber: z.number().int(), episodeCount: z.number().int().min(0) })),
+  /** 不在新结构里、标为临时的季单元的季号 */
+  orphanSeasons: z.array(z.number().int()),
+  reresolve: EpisodeReresolveResult,
+  /** 切换后元数据刷新结果(refreshed / skipped / failed) */
+  refresh: z.string(),
+});
+export type EpisodeGroupSetResult = z.infer<typeof EpisodeGroupSetResult>;
diff --git a/packages/db/migrations/0075_entity_episode_group.ts b/packages/db/migrations/0075_entity_episode_group.ts
new file mode 100644
index 00000000..b9e59ad0
--- /dev/null
+++ b/packages/db/migrations/0075_entity_episode_group.ts
@@ -0,0 +1,31 @@
+import type { Kysely } from "kysely";
+import { execDdl } from "../src/migration-helpers.ts";
+
+// 作品的季集结构(剧集组):null = TMDB 默认季;否则为 TMDB 剧集组 id(/tv/episode_group/{id}),季表与季 / 集单元按组生成。
+// 名称冗余存一份(界面显示不用再查 TMDB);选择时间与操作者(`<actor_type>:<actor_id>`)供审计与界面「谁改的」。
+
+// biome-ignore lint/suspicious/noExplicitAny: 迁移不依赖应用表类型
+export async function up(db: Kysely<any>): Promise<void> {
+  await execDdl(
+    db,
+    `
+alter table media_entity add column episode_group_id text;
+alter table media_entity add column episode_group_name text;
+alter table media_entity add column episode_group_set_at timestamptz;
+alter table media_entity add column episode_group_set_by text;
+`,
+  );
+}
+
+// biome-ignore lint/suspicious/noExplicitAny: 同上
+export async function down(db: Kysely<any>): Promise<void> {
+  await execDdl(
+    db,
+    `
+alter table media_entity drop column if exists episode_group_set_by;
+alter table media_entity drop column if exists episode_group_set_at;
+alter table media_entity drop column if exists episode_group_name;
+alter table media_entity drop column if exists episode_group_id;
+`,
+  );
+}
diff --git a/packages/db/src/types.ts b/packages/db/src/types.ts
index 4daaf3b8..b358b86b 100644
--- a/packages/db/src/types.ts
+++ b/packages/db/src/types.ts
@@ -952,6 +952,10 @@ export interface MediaEntityTable {
   created_at: GeneratedTimestamptz;
   updated_at: GeneratedTimestamptz;
   naming_override: Json | null;
+  episode_group_id: string | null;
+  episode_group_name: string | null;
+  episode_group_set_at: Timestamptz | null;
+  episode_group_set_by: string | null;
 }
 
 export interface MediaServerInstanceTable {
diff --git a/packages/domain/src/episode-resolution/convert.ts b/packages/domain/src/episode-resolution/convert.ts
index a27298f3..9712801b 100644
--- a/packages/domain/src/episode-resolution/convert.ts
+++ b/packages/domain/src/episode-resolution/convert.ts
@@ -3,7 +3,7 @@ import { cumulativeSeasons, seasonOf } from "./table.ts";
 import type { CanonicalEpisodes, SeasonTable } from "./types.ts";
 import { validateEpisodes } from "./validate.ts";
 
-export type ConversionMethod = "absolute_in_season" | "absolute_cross_season" | "air_date";
+export type ConversionMethod = "absolute_in_season" | "absolute_cross_season" | "air_date" | "tmdb_season";
 
 export interface ConversionCandidate {
   method: ConversionMethod;
@@ -88,6 +88,33 @@ export function airDateCandidates(airDate: string, table: SeasonTable, season: n
   return hits.map((canonical) => ({ method: "air_date", canonical, evidence: `air_date:${iso}` }));
 }
 
+/**
+ * 剧集组结构下按 TMDB 默认季集换算:把发布者的季集当作 TMDB 默认季集,经季表的 origins 对照到组内季集。
+ * 区间内每一集都要能对上,且落在同一季、组内集号连续,否则不成立。季 0 不换。
+ */
+export function tmdbSeasonCandidate(
+  season: number,
+  episodes: EpisodeRange,
+  table: SeasonTable,
+): ConversionCandidate | null {
+  const origins = table.origins;
+  if (!origins?.length || season < 1 || episodes.end - episodes.start > 200) return null;
+  const hits: { season: number; episode: number }[] = [];
+  for (let e = episodes.start; e <= episodes.end; e++) {
+    const o = origins.find((x) => x.tmdbSeason === season && x.tmdbEpisode === e);
+    if (!o) return null;
+    hits.push(o);
+  }
+  const first = hits[0]!;
+  if (hits.some((h, i) => h.season !== first.season || h.episode !== first.episode + i)) return null;
+  const pad = (n: number) => String(n).padStart(2, "0");
+  return {
+    method: "tmdb_season",
+    canonical: { season: first.season, episodes: { start: first.episode, end: hits.at(-1)!.episode } },
+    evidence: `tmdb_season:S${pad(season)}E${pad(episodes.start)}`,
+  };
+}
+
 export interface ConversionOutcome {
   /** 去重后、校验为 pass 的候选 */
   candidates: ConversionCandidate[];
@@ -117,6 +144,10 @@ export function convertEpisodes(input: {
       if (cross.kind === "split") evidence.push(cross.evidence);
     }
   }
+  if (episodes && season !== null) {
+    const origin = tmdbSeasonCandidate(season, episodes, table);
+    if (origin) raw.push(origin);
+  }
   if (input.variety && airDate) {
     raw.push(...airDateCandidates(airDate, table, seasonInferred ? null : season));
   }
diff --git a/packages/domain/src/episode-resolution/index.ts b/packages/domain/src/episode-resolution/index.ts
index 4a1ea2e9..3772cadf 100644
--- a/packages/domain/src/episode-resolution/index.ts
+++ b/packages/domain/src/episode-resolution/index.ts
@@ -7,6 +7,7 @@ export {
   convertEpisodes,
   crossSeasonCandidate,
   inSeasonCandidates,
+  tmdbSeasonCandidate,
 } from "./convert.ts";
 export { CONVERSION_NEAR_DAYS, resolveEpisodes } from "./resolve.ts";
 export { applyRule, type RuleApplication, ruleSpecificity, selectRule } from "./rules.ts";
diff --git a/packages/domain/src/episode-resolution/types.ts b/packages/domain/src/episode-resolution/types.ts
index d3159987..5c7cc183 100644
--- a/packages/domain/src/episode-resolution/types.ts
+++ b/packages/domain/src/episode-resolution/types.ts
@@ -13,9 +13,22 @@ export interface SeasonInfo {
   episodes?: SeasonEpisodeInfo[];
 }
 
+/** 剧集组结构下一集的 TMDB 默认季集 → 组内季集 */
+export interface SeasonOrigin {
+  tmdbSeason: number;
+  tmdbEpisode: number;
+  season: number;
+  episode: number;
+}
+
 /** 作品的季表(来自元数据,调用方组装)。季 0(特别篇)可以在表里,换算时忽略 */
 export interface SeasonTable {
   seasons: SeasonInfo[];
+  /**
+   * 作品选了 TMDB 剧集组时:每集的 TMDB 默认季集与组内季集对照。发布者按 TMDB 默认季编号(S01E14)而作品按组分季时,
+   * 换算一步按它把原号换成组内季集(方式 tmdb_season)。默认季结构不给。
+   */
+  origins?: SeasonOrigin[];
   /** 最新季;null 时取表中最大季号 */
   latestSeason: number | null;
   /** 作品已完结:完结后不再有「元数据滞后」放行 */
@@ -58,6 +71,7 @@ export type EpisodeResolutionMethod =
   | "absolute_in_season"
   | "absolute_cross_season"
   | "air_date"
+  | "tmdb_season"
   | "unverified"
   | "unresolved"
   | "skipped";
diff --git a/packages/domain/test/episode-resolution.test.ts b/packages/domain/test/episode-resolution.test.ts
index 3602a541..6b60e67e 100644
--- a/packages/domain/test/episode-resolution.test.ts
+++ b/packages/domain/test/episode-resolution.test.ts
@@ -280,3 +280,39 @@ describe("resolveEpisodes 规则", () => {
     expect(r).toMatchObject({ method: "unresolved", ruleFailed: "x" });
   });
 });
+
+describe("resolveEpisodes 剧集组:按 TMDB 默认季集换算", () => {
+  // TMDB 默认 S1 共 25 集;剧集组拆成 S1(1–12)、S2(13–25)
+  const grouped: SeasonTable = {
+    ...table([12, 13]),
+    origins: Array.from({ length: 25 }, (_, k) => ({
+      tmdbSeason: 1,
+      tmdbEpisode: k + 1,
+      season: k < 12 ? 1 : 2,
+      episode: k < 12 ? k + 1 : k - 11,
+    })),
+  };
+
+  it("S01E14(按 TMDB 默认季编号)→ 组内 S02E02", () => {
+    const r = run({ season: 1, episodes: ep(14) }, grouped);
+    expect(r).toMatchObject({ method: "tmdb_season", canonical: { season: 2, episodes: ep(2) } });
+    expect(r.evidence).toContain("tmdb_season:S01E14");
+  });
+
+  it("「- 13」季号推定:跨季绝对集号与默认季对照同解,归第 2 季第 1 集", () => {
+    const r = run({ season: 1, seasonInferred: true, episodes: ep(13) }, grouped);
+    expect(r.canonical).toEqual({ season: 2, episodes: ep(1) });
+    expect(["absolute_cross_season", "tmdb_season"]).toContain(r.method);
+  });
+
+  it("区间跨组不换;组内号本身对得上时原号优先", () => {
+    expect(run({ season: 1, episodes: ep(12, 13) }, grouped).method).toBe("unresolved");
+    expect(run({ season: 2, episodes: ep(3) }, grouped)).toMatchObject({ method: "raw" });
+    expect(run({ season: 1, episodes: ep(14, 15) }, grouped).canonical).toEqual({ season: 2, episodes: ep(2, 3) });
+  });
+
+  it("没有 origins(默认季结构)时不出这种换算", () => {
+    const { origins: _o, ...plain } = grouped;
+    expect(run({ season: 1, episodes: ep(14) }, plain).method).toBe("unresolved");
+  });
+});