diff --git a/src/connectors/migration-studio.ts b/src/connectors/migration-studio.ts
new file mode 100644
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--- /dev/null
+++ b/src/connectors/migration-studio.ts
@@ -0,0 +1,134 @@
+/**
+ * `connectors/migration-studio.ts` — HSP-085: Migration Studio i kundportalen.
+ *
+ *   T01: an EJ importerbart objekt döljs inte ur nämnaren — objects that
+ *   CANNOT be imported remain in the denominator; the import-ratio is
+ *   calculated over the FULL set (importable + non-importable), so hiding
+ *   failures would falsify the ratio.
+ *   T02: en uppgift kan återupptas efter sessionbyte — the Studio's state
+ *   (mapping, checkpoint, decided conflicts) persists in a resumable session
+ *   record keyed by migrationId; a session change picks up where the last
+ *   session stopped.
+ *   T03: en importerad CRM-lista marknadsförs INTE som komplett Microsoft
+ *   365-ersättning — the coverage claim is SCOPED (what was imported, what
+ *   the coverage covers), never a generic total badge.
+ */
+
+export interface MigrationSourceObject {
+  objectId: string;
+  name: string;
+  /** Can this object be imported into the target? */
+  importable: boolean;
+  /** Why NOT importable (T01: the reason is ALWAYS recorded for non-importable). */
+  nonImportableReason?: string;
+  /** The object's tenant (T03: cross-tenant objects are non-importable). */
+  tenantId: string;
+}
+
+export interface ConflictRecord {
+  conflictId: string;
+  objectId: string;
+  kind: 'name_collision' | 'missing_field' | 'type_mismatch';
+  /** Has the customer decided on this conflict? */
+  resolved: boolean;
+  resolution?: 'skip' | 'overwrite' | 'merge';
+}
+
+export interface MigrationSession {
+  migrationId: string;
+  tenantId: string;
+  /** T02: the checkpoint (batch position) — resumable across sessions. */
+  checkpointCursor: string;
+  /** T02: decided conflicts persist across sessions. */
+  resolvedConflicts: ReadonlyArray<string>;
+  state: 'mapping' | 'dry_run' | 'conflict_review' | 'reconciliation' | 'final_approval';
+}
+
+// -----------------------------------------------------------------------------
+// T01: the import ratio counts EVERY source object in the denominator
+// -----------------------------------------------------------------------------
+
+export interface ImportRatio {
+  totalSourceObjects: number;
+  importableCount: number;
+  nonImportableCount: number;
+  /** importable / total — non-importable objects stay in the DENOMINATOR. */
+  ratio: number;
+  /** The non-importable objects with their reasons (always visible). */
+  nonImportable: ReadonlyArray<{ objectId: string; reason: string }>;
+}
+
+export function computeImportRatio(source: ReadonlyArray<MigrationSourceObject>): ImportRatio {
+  const importable = source.filter((o) => o.importable);
+  const nonImportable = source.filter((o) => !o.importable);
+  const total = source.length;
+  return {
+    totalSourceObjects: total,
+    importableCount: importable.length,
+    nonImportableCount: nonImportable.length,
+    ratio: total === 0 ? 0 : Math.round((importable.length / total) * 100) / 100,
+    nonImportable: nonImportable.map((o) => ({
+      objectId: o.objectId,
+      reason: o.nonImportableReason ?? 'anledning ej angiven',
+    })),
+  };
+}
+
+// -----------------------------------------------------------------------------
+// T02: session resume
+// -----------------------------------------------------------------------------
+
+export interface ResumeDecision {
+  state: 'resumed' | 'fresh';
+  checkpointCursor: string;
+  resolvedConflicts: ReadonlyArray<string>;
+}
+
+/**
+ * T02: resume a migration after a session change. The session record
+ * (checkpoint + decided conflicts) persists; a new session picks up EXACTLY
+ * where the old one left off.
+ */
+export function resumeMigration(
+  stored: MigrationSession | undefined,
+  requestingTenantId: string,
+): ResumeDecision {
+  if (!stored || stored.tenantId !== requestingTenantId) {
+    return { state: 'fresh', checkpointCursor: '0', resolvedConflicts: [] };
+  }
+  return {
+    state: 'resumed',
+    checkpointCursor: stored.checkpointCursor,
+    resolvedConflicts: [...stored.resolvedConflicts],
+  };
+}
+
+// -----------------------------------------------------------------------------
+// T03: scoped coverage claim
+// -----------------------------------------------------------------------------
+
+export interface CoverageClaim {
+  /** T03: the claim is SCOPED — what WAS imported, not a generic total. */
+  scope: string;
+  importedCount: number;
+  /** The denominator INCLUDES non-importable objects (T01). */
+  totalSourceObjects: number;
+  nonImportableCount: number;
+}
+
+/**
+ * T03: the coverage claim is SCOPED (a defined scope, never a total generic
+ * badge). "100% CRM-listor" means CRM lists specifically — never "complete
+ * Microsoft 365 replacement".
+ */
+export function buildCoverageClaim(
+  scope: string,
+  ratio: ImportRatio,
+): CoverageClaim {
+  return {
+    scope: `Migration coverage for '${scope}' — ${ratio.importableCount} av ${ratio.totalSourceObjects} objekt importerade (${ratio.nonImportableCount} ej importerbarta, redovisade)`,
+    importedCount: ratio.importableCount,
+    totalSourceObjects: ratio.totalSourceObjects,
+    nonImportableCount: ratio.nonImportableCount,
+  };
+}
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diff --git a/tests/connectors/migration-studio.test.ts b/tests/connectors/migration-studio.test.ts
new file mode 100644
index 0000000..4b59239
--- /dev/null
+++ b/tests/connectors/migration-studio.test.ts
@@ -0,0 +1,99 @@
+/**
+ * `migration-studio.test.ts` — HSP-085 acceptance:
+ *   T01: an EJ importerbart objekt döljs inte ur nämnaren.
+ *   T02: en uppgift kan återupptas efter sessionbyte.
+ *   T03: en importerad CRM-lista marknadsförs inte som komplett M365-ersättning.
+ * Runner: vitest (0pt-konventionen).
+ */
+import { describe, expect, it } from 'vitest';
+import {
+  computeImportRatio,
+  resumeMigration,
+  buildCoverageClaim,
+  type MigrationSourceObject,
+  type MigrationSession,
+} from '../../src/connectors/migration-studio';
+
+function sourceSet(): MigrationSourceObject[] {
+  return [
+    { objectId: 'obj_1', name: 'CRM-lista: kunder', importable: true, tenantId: 't_1' },
+    { objectId: 'obj_2', name: 'CRM-lista: leads', importable: true, tenantId: 't_1' },
+    { objectId: 'obj_3', name: 'M365 mail-box', importable: false, nonImportableReason: 'mail är utanför migrationsscopet (p0st äger mail)', tenantId: 't_1' },
+    { objectId: 'obj_4', name: 'Cross-tenant doc', importable: false, nonImportableReason: 'annan tenant', tenantId: 't_other' },
+  ];
+}
+
+describe('HSP-085-T01: ej importerbart objekt döljs inte ur nämnaren', () => {
+  it('the ratio counts EVERY source object in the denominator (non-importable stays)', () => {
+    const ratio = computeImportRatio(sourceSet());
+    expect(ratio.totalSourceObjects).toBe(4);
+    expect(ratio.importableCount).toBe(2);
+    expect(ratio.nonImportableCount).toBe(2);
+    // 2/4 = 0.5 — NOT 2/2 = 1.0 (which would be hiding the failures).
+    expect(ratio.ratio).toBe(0.5);
+  });
+
+  it('the non-importable objects are ALWAYS listed with their reasons', () => {
+    const ratio = computeImportRatio(sourceSet());
+    expect(ratio.nonImportable).toHaveLength(2);
+    expect(ratio.nonImportable.some((n) => n.reason.includes('mail'))).toBe(true);
+    expect(ratio.nonImportable.some((n) => n.reason.includes('annan tenant'))).toBe(true);
+  });
+
+  it('a fully-importable source gives ratio 1.0 (honest, no non-importable to hide)', () => {
+    const ratio = computeImportRatio([
+      { objectId: 'a', name: 'a', importable: true, tenantId: 't' },
+    ]);
+    expect(ratio.ratio).toBe(1);
+    expect(ratio.nonImportable).toEqual([]);
+  });
+});
+
+describe('HSP-085-T02: uppgift kan återupptas efter sessionbyte', () => {
+  const stored: MigrationSession = {
+    migrationId: 'mig_1',
+    tenantId: 't_1',
+    checkpointCursor: 'batch_3',
+    resolvedConflicts: ['conflict_a', 'conflict_b'],
+    state: 'conflict_review',
+  };
+
+  it('a session change RESUMES from the stored checkpoint + resolved conflicts', () => {
+    const result = resumeMigration(stored, 't_1');
+    expect(result.state).toBe('resumed');
+    expect(result.checkpointCursor).toBe('batch_3');
+    expect(result.resolvedConflicts).toEqual(['conflict_a', 'conflict_b']);
+  });
+
+  it('a session change to a DIFFERENT tenant starts FRESH (no cross-tenant resume)', () => {
+    const result = resumeMigration(stored, 't_other');
+    expect(result.state).toBe('fresh');
+    expect(result.checkpointCursor).toBe('0');
+  });
+
+  it('no stored session starts fresh', () => {
+    const result = resumeMigration(undefined, 't_1');
+    expect(result.state).toBe('fresh');
+    expect(result.checkpointCursor).toBe('0');
+  });
+});
+
+describe('HSP-085-T03: CRM-lista marknadsförs inte som komplett M365-ersättning', () => {
+  it('the coverage claim is SCOPED to what was imported (never a generic total)', () => {
+    const ratio = computeImportRatio(sourceSet());
+    const claim = buildCoverageClaim('CRM-listor', ratio);
+    expect(claim.scope).toContain('CRM-listor');
+    expect(claim.scope).toContain('2 av 4');
+    expect(claim.scope).toContain('ej importerbarta');
+    // NEVER claims a generic total badge.
+    expect(claim.scope.toLowerCase()).not.toContain('complete');
+    expect(claim.scope.toLowerCase()).not.toContain('komplett microsoft');
+  });
+
+  it('the claim carries the NON-IMPORTABLE count (the honest denominator)', () => {
+    const ratio = computeImportRatio(sourceSet());
+    const claim = buildCoverageClaim('CRM-listor', ratio);
+    expect(claim.nonImportableCount).toBe(2);
+    expect(claim.totalSourceObjects).toBe(4);
+  });
+});
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