diff --git a/packages/core/api/client.ts b/packages/core/api/client.ts
index a0a034919..db1b012a7 100644
--- a/packages/core/api/client.ts
+++ b/packages/core/api/client.ts
@@ -74,6 +74,8 @@ import type {
   SendChatMessageResponse,
   CancelTaskResponse,
   Team,
+  TeamMembership,
+  ListTeamMembersResponse,
   CreateTeamRequest,
   UpdateTeamRequest,
   ListTeamsResponse,
@@ -187,7 +189,10 @@ import {
   EMPTY_LIST_AUTOPILOTS_RESPONSE,
   ListIssuesResponseSchema,
   ListTeamsResponseSchema,
+  ListTeamMembersResponseSchema,
+  EMPTY_LIST_TEAM_MEMBERS_RESPONSE,
   TeamSchema,
+  TeamMembershipSchema,
   ListWebhookDeliveriesResponseSchema,
   RuntimeHourlyActivityListSchema,
   RuntimeUsageByAgentListSchema,
@@ -1603,6 +1608,31 @@ export class ApiClient {
     return parseOrWarn(raw, TeamSchema, { endpoint: "PATCH /api/teams/:id" });
   }
 
+  async updateTeamMembership(id: string, data: { sort_order: number }): Promise<TeamMembership> {
+    const raw = await this.fetch<unknown>(`/api/teams/${id}/membership`, {
+      method: "PATCH",
+      body: JSON.stringify(data),
+    });
+    return parseOrWarn(raw, TeamMembershipSchema, { endpoint: "PATCH /api/teams/:id/membership" });
+  }
+
+  async replaceTeamMembers(id: string, memberIds: string[]): Promise<ListTeamMembersResponse> {
+    const raw = await this.fetch<unknown>(`/api/teams/${id}/members`, {
+      method: "PUT",
+      body: JSON.stringify({ member_ids: memberIds }),
+    });
+    return parseWithFallback(raw, ListTeamMembersResponseSchema, EMPTY_LIST_TEAM_MEMBERS_RESPONSE, {
+      endpoint: "PUT /api/teams/:id/members",
+    });
+  }
+
+  async listTeamMembers(id: string): Promise<ListTeamMembersResponse> {
+    const raw = await this.fetch<unknown>(`/api/teams/${id}/members`);
+    return parseWithFallback(raw, ListTeamMembersResponseSchema, EMPTY_LIST_TEAM_MEMBERS_RESPONSE, {
+      endpoint: "GET /api/teams/:id/members",
+    });
+  }
+
   async archiveTeam(id: string): Promise<Team> {
     const raw = await this.fetch<unknown>(`/api/teams/${id}`, { method: "DELETE" });
     return parseOrWarn(raw, TeamSchema, { endpoint: "DELETE /api/teams/:id" });
diff --git a/packages/core/api/schemas.ts b/packages/core/api/schemas.ts
index 77168887d..bf02589b4 100644
--- a/packages/core/api/schemas.ts
+++ b/packages/core/api/schemas.ts
@@ -18,6 +18,7 @@ import type {
   InboxWorkspaceUnread,
   ListIssuesResponse,
   ListTeamsResponse,
+  ListTeamMembersResponse,
   ListWebhookDeliveriesResponse,
   SearchIssuesResponse,
   SearchProjectsResponse,
@@ -324,8 +325,35 @@ export const TeamSchema = z.object({
   created_by: z.string().nullable().default(null),
   created_at: z.string().default(""),
   updated_at: z.string().default(""),
+  is_member: z.boolean().default(false),
+  sort_order: z.number().default(0),
 }).loose();
 
+// PATCH /api/teams/{id}/membership — the caller's own sort position.
+export const TeamMembershipSchema = z.object({
+  team_id: z.string().default(""),
+  sort_order: z.number().default(0),
+}).loose();
+
+export const TeamMemberSchema = z.object({
+  user_id: z.string(),
+  name: z.string().default(""),
+  email: z.string().default(""),
+  avatar_url: z.string().nullable().default(null),
+  role: z.string().default("member"),
+  created_at: z.string().default(""),
+}).loose();
+
+export const ListTeamMembersResponseSchema = z.object({
+  members: z.array(TeamMemberSchema).default([]),
+  total: z.number().default(0),
+});
+
+export const EMPTY_LIST_TEAM_MEMBERS_RESPONSE: ListTeamMembersResponse = {
+  members: [],
+  total: 0,
+};
+
 export const ListTeamsResponseSchema = z.object({
   teams: z.array(TeamSchema).default([]),
   total: z.number().default(0),
@@ -344,6 +372,8 @@ export const EMPTY_TEAM: Team = {
   created_by: null,
   created_at: "",
   updated_at: "",
+  is_member: false,
+  sort_order: 0,
 };
 
 export const EMPTY_LIST_TEAMS_RESPONSE: ListTeamsResponse = {
diff --git a/packages/core/issues/stores/quick-create-store.ts b/packages/core/issues/stores/quick-create-store.ts
index 11724f866..93dae2922 100644
--- a/packages/core/issues/stores/quick-create-store.ts
+++ b/packages/core/issues/stores/quick-create-store.ts
@@ -27,8 +27,6 @@ interface QuickCreateState {
   setLastActor: (type: QuickCreateActorType | null, id: string | null) => void;
   lastProjectId: string | null;
   setLastProjectId: (id: string | null) => void;
-  lastTeamId: string | null;
-  setLastTeamId: (id: string | null) => void;
   prompt: string;
   setPrompt: (prompt: string) => void;
   clearPrompt: () => void;
@@ -44,8 +42,6 @@ export const useQuickCreateStore = create<QuickCreateState>()(
       setLastActor: (type, id) => set({ lastActorType: type, lastActorId: id }),
       lastProjectId: null,
       setLastProjectId: (id) => set({ lastProjectId: id }),
-      lastTeamId: null,
-      setLastTeamId: (id) => set({ lastTeamId: id }),
       prompt: "",
       setPrompt: (prompt) => set({ prompt }),
       clearPrompt: () => set({ prompt: "" }),
diff --git a/packages/core/issues/surface/query-plan.ts b/packages/core/issues/surface/query-plan.ts
index 5ea411b41..7f46d8516 100644
--- a/packages/core/issues/surface/query-plan.ts
+++ b/packages/core/issues/surface/query-plan.ts
@@ -3,11 +3,7 @@ import type {
   AssigneeGroupedIssuesFilter,
   MyIssuesFilter,
 } from "../queries";
-import {
-  issueScopeKey,
-  UnsupportedIssueScopeError,
-  type IssueScope,
-} from "./scope";
+import { issueScopeKey, type IssueScope } from "./scope";
 
 export type IssueSurfaceQueryPlan =
   | {
@@ -163,7 +159,22 @@ export function buildIssueSurfaceQueryPlan(
             : {},
       };
     }
-    case "team":
-      throw new UnsupportedIssueScopeError(scope, "issue surface query plan");
+    case "team": {
+      // Mirrors the project plan: team_id is a real server filter on both
+      // the list and grouped endpoints, so the team surface gets its own
+      // cache entry, and issues created from it default into the team.
+      const queryFilter = { team_id: scope.teamId };
+      return {
+        kind: "scoped",
+        scopeKey,
+        queryScope: scopeKey,
+        queryFilter,
+        groupedScopeFilter: queryFilter,
+        loadMoreScope: scopeKey,
+        loadMoreFilter: queryFilter,
+        userId: undefined,
+        createDefaults: { team_id: scope.teamId },
+      };
+    }
   }
 }
diff --git a/packages/core/issues/surface/scope.test.ts b/packages/core/issues/surface/scope.test.ts
index 7b08477be..b0ad70745 100644
--- a/packages/core/issues/surface/scope.test.ts
+++ b/packages/core/issues/surface/scope.test.ts
@@ -1,8 +1,5 @@
 import { describe, expect, it } from "vitest";
-import {
-  UnsupportedIssueScopeError,
-  issueScopeKey,
-} from "./scope";
+import { issueScopeKey } from "./scope";
 import { buildIssueSurfaceQueryPlan } from "./query-plan";
 
 describe("issue surface scope", () => {
@@ -145,10 +142,16 @@ describe("issue surface scope", () => {
     });
   });
 
-  it("throws for team until the issue API has a team filter", () => {
-    const scope = { type: "team" as const, teamId: "t1" };
-    expect(() => buildIssueSurfaceQueryPlan(scope)).toThrow(
-      UnsupportedIssueScopeError,
-    );
+  it("builds the team query plan mirroring the project shape", () => {
+    expect(
+      buildIssueSurfaceQueryPlan({ type: "team", teamId: "t1" }),
+    ).toMatchObject({
+      kind: "scoped",
+      scopeKey: "team:t1",
+      queryScope: "team:t1",
+      queryFilter: { team_id: "t1" },
+      groupedScopeFilter: { team_id: "t1" },
+      createDefaults: { team_id: "t1" },
+    });
   });
 });
diff --git a/packages/core/layout/sidebar-store.ts b/packages/core/layout/sidebar-store.ts
new file mode 100644
index 000000000..f2dac91ee
--- /dev/null
+++ b/packages/core/layout/sidebar-store.ts
@@ -0,0 +1,32 @@
+"use client";
+
+import { create } from "zustand";
+import { createJSONStorage, persist } from "zustand/middleware";
+import { createWorkspaceAwareStorage, registerForWorkspaceRehydration } from "../platform/workspace-storage";
+import { defaultStorage } from "../platform/storage";
+
+// Sidebar group collapse state, persisted per workspace (same
+// workspace-aware storage the quick-create prefs use). Keys are group ids:
+// "pinned", "workspace", "more", "teams", and `team:{teamId}` for each team
+// group. Absent key = expanded — groups default open so a fresh workspace
+// shows its whole structure.
+interface SidebarState {
+  collapsed: Record<string, boolean>;
+  setGroupCollapsed: (key: string, collapsed: boolean) => void;
+}
+
+export const useSidebarStore = create<SidebarState>()(
+  persist(
+    (set) => ({
+      collapsed: {},
+      setGroupCollapsed: (key, collapsed) =>
+        set((s) => ({ collapsed: { ...s.collapsed, [key]: collapsed } })),
+    }),
+    {
+      name: "multica_sidebar",
+      storage: createJSONStorage(() => createWorkspaceAwareStorage(defaultStorage)),
+    },
+  ),
+);
+
+registerForWorkspaceRehydration(() => useSidebarStore.persist.rehydrate());
diff --git a/packages/core/modals/store.ts b/packages/core/modals/store.ts
index cb4aae4be..c02d23be3 100644
--- a/packages/core/modals/store.ts
+++ b/packages/core/modals/store.ts
@@ -8,6 +8,7 @@ type ModalType =
   | "quick-create-issue"
   | "create-project"
   | "create-squad"
+  | "create-team"
   | "feedback"
   | "issue-set-parent"
   | "issue-add-child"
diff --git a/packages/core/package.json b/packages/core/package.json
index 76b456d33..17ade6ada 100644
--- a/packages/core/package.json
+++ b/packages/core/package.json
@@ -73,6 +73,8 @@
     "./teams": "./teams/index.ts",
     "./teams/queries": "./teams/queries.ts",
     "./teams/mutations": "./teams/mutations.ts",
+    "./teams/default-team": "./teams/default-team.ts",
+    "./layout/sidebar-store": "./layout/sidebar-store.ts",
     "./labels": "./labels/index.ts",
     "./labels/queries": "./labels/queries.ts",
     "./labels/mutations": "./labels/mutations.ts",
diff --git a/packages/core/paths/paths.ts b/packages/core/paths/paths.ts
index cd0b3d5d8..df9ace968 100644
--- a/packages/core/paths/paths.ts
+++ b/packages/core/paths/paths.ts
@@ -20,8 +20,19 @@ function workspaceScoped(slug: string) {
     root: () => `${ws}/issues`,
     usage: () => `${ws}/usage`,
     issues: () => `${ws}/issues`,
-    issueDetail: (id: string) => `${ws}/issues/${encode(id)}`,
+    // Issue detail is identifier-first (Linear-style /issue/NAI-3): the team
+    // rides in the identifier, never in a nested path segment, so moving an
+    // issue between teams can't orphan the URL (old identifiers keep
+    // resolving via the server-side alias). The same route accepts a UUID —
+    // internal navigation passes ids, shared links pass identifiers.
+    issueDetail: (idOrIdentifier: string) => `${ws}/issue/${encode(idOrIdentifier)}`,
     teams: () => `${ws}/teams`,
+    // Team-scoped surfaces, addressed by team key (readable, stable: keys
+    // freeze once a team has issues) — /team/ENG/issues, Linear-style.
+    teamIssues: (key: string) => `${ws}/team/${encode(key)}/issues`,
+    teamProjects: (key: string) => `${ws}/team/${encode(key)}/projects`,
+    teamAutopilots: (key: string) => `${ws}/team/${encode(key)}/autopilots`,
+    teamSettings: (key: string) => `${ws}/team/${encode(key)}/settings`,
     projects: () => `${ws}/projects`,
     projectDetail: (id: string) => `${ws}/projects/${encode(id)}`,
     autopilots: () => `${ws}/autopilots`,
diff --git a/packages/core/paths/reserved-slugs.ts b/packages/core/paths/reserved-slugs.ts
index efafda502..73e762a8f 100644
--- a/packages/core/paths/reserved-slugs.ts
+++ b/packages/core/paths/reserved-slugs.ts
@@ -90,6 +90,7 @@ export const RESERVED_SLUGS: ReadonlySet<string> = new Set([
   "settings",
   "workspaces",
   "teams",
+  "team",
 
   // API / integration prefixes
   // `api` above already covers `/api/*`; these guard against future top-level
diff --git a/packages/core/teams/default-team.ts b/packages/core/teams/default-team.ts
new file mode 100644
index 000000000..a77665dfe
--- /dev/null
+++ b/packages/core/teams/default-team.ts
@@ -0,0 +1,15 @@
+import type { Team } from "../types";
+
+/**
+ * The team a new issue defaults into when no other context (route, parent,
+ * single-team project) applies: the first team in the user's personal order.
+ * Falls back to the workspace default team for users whose membership rows
+ * predate the membership rollout, then to any active team.
+ */
+export function creationDefaultTeamId(teams: Team[]): string | undefined {
+  const active = teams.filter((team) => !team.archived_at);
+  const mine = active
+    .filter((team) => team.is_member)
+    .sort((a, b) => a.sort_order - b.sort_order);
+  return (mine[0] ?? active.find((team) => team.is_default) ?? active[0])?.id;
+}
diff --git a/packages/core/teams/index.ts b/packages/core/teams/index.ts
index cd38dbd29..8c78026d5 100644
--- a/packages/core/teams/index.ts
+++ b/packages/core/teams/index.ts
@@ -1,2 +1,15 @@
-export { teamKeys, teamListOptions, activeTeamListOptions } from "./queries";
-export { useCreateTeam, useUpdateTeam, useArchiveTeam } from "./mutations";
+export {
+  teamKeys,
+  teamListOptions,
+  activeTeamListOptions,
+  myTeamListOptions,
+  teamMembersOptions,
+} from "./queries";
+export {
+  useCreateTeam,
+  useUpdateTeam,
+  useArchiveTeam,
+  useUpdateTeamMembership,
+  useReplaceTeamMembers,
+} from "./mutations";
+export { creationDefaultTeamId } from "./default-team";
diff --git a/packages/core/teams/mutations.ts b/packages/core/teams/mutations.ts
index 379880dee..e9373bf75 100644
--- a/packages/core/teams/mutations.ts
+++ b/packages/core/teams/mutations.ts
@@ -54,6 +54,53 @@ export function useUpdateTeam() {
   });
 }
 
+export function useUpdateTeamMembership() {
+  const qc = useQueryClient();
+  const wsId = useWorkspaceId();
+  return useMutation({
+    mutationFn: ({ id, sort_order }: { id: string; sort_order: number }) =>
+      api.updateTeamMembership(id, { sort_order }),
+    // Optimistic: sidebar ordering must not snap back while the PATCH is in
+    // flight. Fractional sort keys mean only the dragged team's row changes.
+    onMutate: async ({ id, sort_order }) => {
+      await qc.cancelQueries({ queryKey: teamKeys.list(wsId) });
+      const prevList = qc.getQueryData<ListTeamsResponse>(teamKeys.list(wsId));
+      qc.setQueryData<ListTeamsResponse>(teamKeys.list(wsId), (old) =>
+        old
+          ? {
+              ...old,
+              teams: old.teams.map((t) => (t.id === id ? { ...t, sort_order } : t)),
+            }
+          : old,
+      );
+      return { prevList };
+    },
+    onError: (_err, _vars, ctx) => {
+      if (ctx?.prevList) qc.setQueryData(teamKeys.list(wsId), ctx.prevList);
+    },
+    onSettled: () => {
+      qc.invalidateQueries({ queryKey: teamKeys.all(wsId) });
+    },
+  });
+}
+
+export function useReplaceTeamMembers() {
+  const qc = useQueryClient();
+  const wsId = useWorkspaceId();
+  return useMutation({
+    mutationFn: ({ id, member_ids }: { id: string; member_ids: string[] }) =>
+      api.replaceTeamMembers(id, member_ids),
+    // No optimistic patch: the config panel closes on save, and the
+    // caller's own is_member may flip (they can add/remove themselves), so
+    // one settled invalidation of the list + members caches is the simplest
+    // correct reconcile.
+    onSettled: (_data, _err, { id }) => {
+      qc.invalidateQueries({ queryKey: teamKeys.all(wsId) });
+      qc.invalidateQueries({ queryKey: teamKeys.members(wsId, id) });
+    },
+  });
+}
+
 export function useArchiveTeam() {
   const qc = useQueryClient();
   const wsId = useWorkspaceId();
diff --git a/packages/core/teams/queries.ts b/packages/core/teams/queries.ts
index f66dc5b12..41f94cd2a 100644
--- a/packages/core/teams/queries.ts
+++ b/packages/core/teams/queries.ts
@@ -4,6 +4,8 @@ import { api } from "../api";
 export const teamKeys = {
   all: (wsId: string) => ["teams", wsId] as const,
   list: (wsId: string) => [...teamKeys.all(wsId), "list"] as const,
+  members: (wsId: string, teamId: string) =>
+    [...teamKeys.all(wsId), "members", teamId] as const,
 };
 
 export function teamListOptions(wsId: string) {
@@ -24,3 +26,25 @@ export function activeTeamListOptions(wsId: string) {
     select: (data) => data.teams.filter((team) => !team.archived_at),
   });
 }
+
+export function teamMembersOptions(wsId: string, teamId: string) {
+  return queryOptions({
+    queryKey: teamKeys.members(wsId, teamId),
+    queryFn: () => api.listTeamMembers(teamId),
+    select: (data) => data.members,
+  });
+}
+
+export function myTeamListOptions(wsId: string) {
+  // The sidebar's Teams section: only teams the user joined, in their
+  // personal order. Same cache entry as teamListOptions (per-observer
+  // select), so reorder patches on the base key reflect here instantly.
+  return queryOptions({
+    queryKey: teamKeys.list(wsId),
+    queryFn: () => api.listTeams(),
+    select: (data) =>
+      data.teams
+        .filter((team) => team.is_member && !team.archived_at)
+        .sort((a, b) => a.sort_order - b.sort_order),
+  });
+}
diff --git a/packages/core/types/index.ts b/packages/core/types/index.ts
index f263aa89b..335c63192 100644
--- a/packages/core/types/index.ts
+++ b/packages/core/types/index.ts
@@ -61,7 +61,7 @@ export type {
 } from "./agent";
 export { RUNTIME_PROFILE_PROTOCOL_FAMILIES } from "./agent";
 export type { Workspace, WorkspaceRepo, Member, MemberRole, User, MemberWithUser, Invitation } from "./workspace";
-export type { Team, CreateTeamRequest, UpdateTeamRequest, ListTeamsResponse } from "./team";
+export type { Team, CreateTeamRequest, UpdateTeamRequest, ListTeamsResponse, TeamMembership, TeamMember, ListTeamMembersResponse } from "./team";
 export type { InboxItem, InboxSeverity, InboxItemType, InboxWorkspaceUnread } from "./inbox";
 export type { NotificationGroupKey, NotificationGroupValue, NotificationPreferences, NotificationPreferenceResponse } from "./notification-preference";
 export type { Comment, CommentType, CommentAuthorType, CommentTriggerPreview, CommentTriggerPreviewAgent, CommentTriggerSource, Reaction } from "./comment";
diff --git a/packages/core/types/team.ts b/packages/core/types/team.ts
index 156e53344..486f35fab 100644
--- a/packages/core/types/team.ts
+++ b/packages/core/types/team.ts
@@ -11,6 +11,10 @@ export interface Team {
   created_by: string | null;
   created_at: string;
   updated_at: string;
+  /** Requesting user's membership view — the sidebar shows only joined
+   *  teams, ordered by sort_order (per-user fractional position). */
+  is_member: boolean;
+  sort_order: number;
 }
 
 export interface CreateTeamRequest {
@@ -18,6 +22,8 @@ export interface CreateTeamRequest {
   key: string;
   description?: string;
   icon?: string | null;
+  /** Workspace members invited alongside the creator (who joins as lead). */
+  member_ids?: string[];
 }
 
 export interface UpdateTeamRequest {
@@ -31,3 +37,25 @@ export interface ListTeamsResponse {
   teams: Team[];
   total: number;
 }
+
+/** Caller's own membership row, as returned by PATCH /api/teams/{id}/membership. */
+export interface TeamMembership {
+  team_id: string;
+  sort_order: number;
+}
+
+/** A team member with user display data (GET /api/teams/{id}/members). */
+export interface TeamMember {
+  user_id: string;
+  name: string;
+  email: string;
+  avatar_url: string | null;
+  /** "lead" | "member" — informational in v1, no privileges attached. */
+  role: string;
+  created_at: string;
+}
+
+export interface ListTeamMembersResponse {
+  members: TeamMember[];
+  total: number;
+}