diff --git a/scripts/kb-update/lib/registry-migrate.mjs b/scripts/kb-update/lib/registry-migrate.mjs
new file mode 100644
index 0000000..98a3267
--- /dev/null
+++ b/scripts/kb-update/lib/registry-migrate.mjs
@@ -0,0 +1,80 @@
+// registry-migrate.mjs — One-shot ai-foundry -> foundry URL remap + reserved
+// schema migration. Pure functions (no I/O) so they are unit-testable; the
+// migrate-ai-foundry.mjs script wires backup + atomic write around them.
+//
+// Microsoft rebranded "Azure AI Foundry" -> "Microsoft Foundry"; doc URLs moved
+// /azure/ai-foundry/ -> /azure/foundry/. Two pages probed in Sesjon 1 are DEAD
+// on a naive prefix swap and need explicit targets.
+
+const AI_FOUNDRY_PREFIX = 'https://learn.microsoft.com/azure/ai-foundry/';
+const FOUNDRY_PREFIX = 'https://learn.microsoft.com/azure/foundry/';
+
+// Probed DEAD pages (Sesjon 1): naive prefix swap 404s, these are the live targets.
+const DEAD_REMAPS = {
+  'https://learn.microsoft.com/azure/ai-foundry/concepts/evaluation-evaluators':
+    'https://learn.microsoft.com/azure/foundry/concepts/built-in-evaluators',
+  'https://learn.microsoft.com/azure/ai-foundry/agent-service':
+    'https://learn.microsoft.com/azure/foundry/agents/overview',
+};
+
+/**
+ * Remap a single registry URL key. DEAD overrides win; otherwise prefix-swap
+ * ai-foundry -> foundry; non-ai-foundry URLs are returned unchanged.
+ * @param {string} url
+ * @returns {string}
+ */
+export function remapKey(url) {
+  if (DEAD_REMAPS[url]) return DEAD_REMAPS[url];
+  if (url.startsWith(AI_FOUNDRY_PREFIX)) {
+    return FOUNDRY_PREFIX + url.slice(AI_FOUNDRY_PREFIX.length);
+  }
+  return url;
+}
+
+/**
+ * Migrate a registry: remap ai-foundry keys (resetting their tracking state so
+ * the next poll re-evaluates them), merge any target collisions, and ensure the
+ * reserved schema fields (authority_source, course) exist on every entry.
+ * Pure — does not mutate the input.
+ * @param {object} registry
+ * @returns {{registry: object, stats: {remapped: number, deadRemapped: number, collisions: number}}}
+ */
+export function migrateRegistry(registry) {
+  const out = { ...registry, urls: {} };
+  const stats = { remapped: 0, deadRemapped: 0, collisions: 0 };
+
+  for (const [url, entry] of Object.entries(registry.urls)) {
+    const target = remapKey(url);
+    const isRemap = target !== url;
+
+    // Normalize every entry to the full schema (reserved fields included).
+    const base = {
+      sitemap_lastmod: entry.sitemap_lastmod ?? null,
+      reference_files: entry.reference_files ?? [],
+      status: entry.status ?? 'unpolled',
+      authority_source: entry.authority_source ?? null,
+      course: entry.course ?? null,
+    };
+
+    let next = base;
+    if (isRemap) {
+      stats.remapped++;
+      if (DEAD_REMAPS[url]) stats.deadRemapped++;
+      // The URL changed — old poll state is invalid; let the next poll decide.
+      next = { ...base, sitemap_lastmod: null, status: 'unpolled' };
+    }
+
+    if (out.urls[target]) {
+      // Two source keys collapsed onto one target — union the reference files.
+      stats.collisions++;
+      const merged = [
+        ...new Set([...out.urls[target].reference_files, ...next.reference_files]),
+      ].sort();
+      out.urls[target] = { ...out.urls[target], ...next, reference_files: merged };
+    } else {
+      out.urls[target] = next;
+    }
+  }
+
+  return { registry: out, stats };
+}
diff --git a/scripts/kb-update/migrate-ai-foundry.mjs b/scripts/kb-update/migrate-ai-foundry.mjs
new file mode 100644
index 0000000..7fd21ba
--- /dev/null
+++ b/scripts/kb-update/migrate-ai-foundry.mjs
@@ -0,0 +1,35 @@
+#!/usr/bin/env node
+// migrate-ai-foundry.mjs — One-shot migration: back up data/, remap registry
+// keys ai-foundry -> foundry (+ 2 probed DEAD targets), migrate reserved schema
+// fields, write atomically. Idempotent: re-running finds nothing to remap.
+// Usage: node migrate-ai-foundry.mjs
+
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { loadRegistry, saveRegistry } from './lib/registry-io.mjs';
+import { backupDir } from './lib/backup.mjs';
+import { migrateRegistry } from './lib/registry-migrate.mjs';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const DATA_DIR = join(__dirname, 'data');
+const PLUGIN_ROOT = join(__dirname, '..', '..');
+const BACKUP_ROOT = join(PLUGIN_ROOT, '.kb-backup');
+
+const registry = loadRegistry(DATA_DIR);
+const before = Object.keys(registry.urls).length;
+
+const { backupPath } = backupDir(DATA_DIR, BACKUP_ROOT);
+console.log(`Backed up data/ -> ${backupPath}`);
+
+const { registry: migrated, stats } = migrateRegistry(registry);
+const after = Object.keys(migrated.urls).length;
+
+saveRegistry(migrated, DATA_DIR);
+
+const remainingAiFoundry = Object.keys(migrated.urls)
+  .filter((u) => u.includes('/azure/ai-foundry/')).length;
+
+console.log('=== ai-foundry -> foundry remap ===');
+console.log(`URLs: ${before} -> ${after} (collisions merged: ${stats.collisions})`);
+console.log(`Remapped: ${stats.remapped} (DEAD explicit targets: ${stats.deadRemapped})`);
+console.log(`Remaining ai-foundry keys: ${remainingAiFoundry} (expect 0)`);
diff --git a/tests/kb-update/test-registry-migrate.test.mjs b/tests/kb-update/test-registry-migrate.test.mjs
new file mode 100644
index 0000000..094536f
--- /dev/null
+++ b/tests/kb-update/test-registry-migrate.test.mjs
@@ -0,0 +1,123 @@
+// tests/kb-update/test-registry-migrate.test.mjs
+// Unit tests for scripts/kb-update/lib/registry-migrate.mjs — the one-shot
+// ai-foundry -> foundry URL remap + reserved-schema migration.
+// Microsoft rebranded "Azure AI Foundry" -> "Microsoft Foundry"; URLs moved
+// /azure/ai-foundry/ -> /azure/foundry/. Two probed pages are DEAD on a naive
+// prefix swap and need explicit targets (verified in Sesjon 1).
+
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { remapKey, migrateRegistry } from '../../scripts/kb-update/lib/registry-migrate.mjs';
+
+const AF = 'https://learn.microsoft.com/azure/ai-foundry/';
+const FD = 'https://learn.microsoft.com/azure/foundry/';
+
+test('remapKey — prefix swap ai-foundry -> foundry', () => {
+  assert.equal(remapKey(AF + 'openai/how-to/manage-costs'), FD + 'openai/how-to/manage-costs');
+  assert.equal(remapKey(AF + 'responsible-ai/openai/content-filter'), FD + 'responsible-ai/openai/content-filter');
+});
+
+test('remapKey — two probed DEAD pages get explicit targets', () => {
+  assert.equal(
+    remapKey('https://learn.microsoft.com/azure/ai-foundry/concepts/evaluation-evaluators'),
+    'https://learn.microsoft.com/azure/foundry/concepts/built-in-evaluators'
+  );
+  assert.equal(
+    remapKey('https://learn.microsoft.com/azure/ai-foundry/agent-service'),
+    'https://learn.microsoft.com/azure/foundry/agents/overview'
+  );
+});
+
+test('remapKey — non-ai-foundry URLs untouched', () => {
+  const other = 'https://learn.microsoft.com/azure/machine-learning/overview';
+  assert.equal(remapKey(other), other);
+  // already-foundry URL is left as-is
+  assert.equal(remapKey(FD + 'what-is-azure-ai-foundry'), FD + 'what-is-azure-ai-foundry');
+});
+
+function fixtureRegistry() {
+  return {
+    version: 1,
+    created_at: '2026-01-01',
+    last_poll: '2026-06-19T11:00:00Z',
+    sitemap_state: { 'azure_en-us_7': { lastmod: '2026-06-01', checked_at: '2026-06-19' } },
+    urls: {
+      [AF + 'openai/how-to/manage-costs']: {
+        sitemap_lastmod: null, reference_files: ['skills/a.md'], status: 'not_in_sitemap',
+      },
+      [AF + 'agent-service']: {
+        sitemap_lastmod: null, reference_files: ['skills/b.md'], status: 'not_in_sitemap',
+      },
+      // already-tracked non-foundry URL must survive untouched
+      'https://learn.microsoft.com/azure/search/rag': {
+        sitemap_lastmod: '2026-05-10', reference_files: ['skills/c.md'], status: 'tracked',
+      },
+    },
+  };
+}
+
+test('migrateRegistry — remaps ai-foundry keys and resets their tracking', () => {
+  const { registry } = migrateRegistry(fixtureRegistry());
+  // keys remapped
+  assert.ok(registry.urls[FD + 'openai/how-to/manage-costs'], 'prefix-swap key missing');
+  assert.ok(registry.urls[FD + 'agents/overview'], 'DEAD-remap key missing');
+  assert.ok(!registry.urls[AF + 'openai/how-to/manage-costs'], 'old ai-foundry key still present');
+  // remapped entries reset so the next poll re-evaluates
+  const e = registry.urls[FD + 'openai/how-to/manage-costs'];
+  assert.equal(e.status, 'unpolled');
+  assert.equal(e.sitemap_lastmod, null);
+  assert.deepEqual(e.reference_files, ['skills/a.md']);
+});
+
+test('migrateRegistry — non-ai-foundry entry preserved verbatim (plus reserved fields)', () => {
+  const { registry } = migrateRegistry(fixtureRegistry());
+  const e = registry.urls['https://learn.microsoft.com/azure/search/rag'];
+  assert.equal(e.status, 'tracked');
+  assert.equal(e.sitemap_lastmod, '2026-05-10');
+  assert.deepEqual(e.reference_files, ['skills/c.md']);
+});
+
+test('migrateRegistry — reserved schema fields present on every entry', () => {
+  const { registry } = migrateRegistry(fixtureRegistry());
+  for (const [url, e] of Object.entries(registry.urls)) {
+    assert.ok('authority_source' in e, `authority_source missing on ${url}`);
+    assert.ok('course' in e, `course missing on ${url}`);
+    assert.equal(e.authority_source, null);
+    assert.equal(e.course, null);
+  }
+});
+
+test('migrateRegistry — top-level registry metadata preserved', () => {
+  const { registry } = migrateRegistry(fixtureRegistry());
+  assert.equal(registry.version, 1);
+  assert.equal(registry.created_at, '2026-01-01');
+  assert.ok(registry.sitemap_state['azure_en-us_7']);
+});
+
+test('migrateRegistry — collision on same target merges reference_files (union, sorted)', () => {
+  const reg = {
+    version: 1, created_at: null, last_poll: null, sitemap_state: {},
+    urls: {
+      // both map to FD + agents/overview (one via DEAD remap, one via prefix swap)
+      [AF + 'agent-service']: { sitemap_lastmod: null, reference_files: ['skills/z.md', 'skills/a.md'], status: 'not_in_sitemap' },
+      [AF + 'agents/overview']: { sitemap_lastmod: null, reference_files: ['skills/a.md', 'skills/m.md'], status: 'not_in_sitemap' },
+    },
+  };
+  const { registry, stats } = migrateRegistry(reg);
+  const e = registry.urls[FD + 'agents/overview'];
+  assert.deepEqual(e.reference_files, ['skills/a.md', 'skills/m.md', 'skills/z.md']);
+  assert.equal(Object.keys(registry.urls).length, 1);
+  assert.ok(stats.collisions >= 1);
+});
+
+test('migrateRegistry — does not mutate the input registry', () => {
+  const input = fixtureRegistry();
+  migrateRegistry(input);
+  assert.ok(input.urls[AF + 'openai/how-to/manage-costs'], 'input was mutated');
+});
+
+test('migrateRegistry — stats count remaps and DEAD remaps', () => {
+  const { stats } = migrateRegistry(fixtureRegistry());
+  assert.equal(stats.remapped, 2);
+  assert.equal(stats.deadRemapped, 1); // agent-service is the only DEAD one in the fixture
+});