diff --git a/.agent/knowledge/data-contracts.md b/.agent/knowledge/data-contracts.md
index b006d1d4..546d7abf 100644
--- a/.agent/knowledge/data-contracts.md
+++ b/.agent/knowledge/data-contracts.md
@@ -718,6 +718,15 @@ Document API and data-shape assumptions that must stay compatible over time.
 - Follow-up action: Once Learn ships its matching fingerprint implementation, verify a sample of correlated `provider`/`resourceLinkId` values produce identical fingerprints across both systems' logs before relying on this for incident tracing.
 - Owner: Codex
 
+## Learn SyncDeck iframe waiting-room handoff
+
+- Date: 2026-08-09
+- Surface: Learn student waiting-room browser handoff
+- Contract: The one-time Learn `waitingLaunchUrl` is consumed in the student's browser and establishes a 10-minute httpOnly `learn_syncdeck_wait` cookie. In production it uses `Secure; SameSite=None; Partitioned` so an LMS-hosted ActiveBits iframe can send the handoff cookie on its same-origin `/wait/status` poll and receive the active student-session URL without a global third-party cookie.
+- Compatibility constraints: Production requires HTTPS. Development retains `SameSite=Lax` without `Secure` or `Partitioned` for local HTTP test environments.
+- Validation rules: The server integration test consumes the one-time URL, asserts production cookie attributes, and verifies that the cookie resolves an active mapping. The existing Playwright waiting-room test verifies the browser transitions to an active student-session URL after a successful status poll. Validate third-party-cookie behavior in a real LMS cross-site iframe before relying on the production integration.
+- Owner: Codex
+
 ## Generic session-store `linkedSessionId` keepalive contract
 
 - Date: 2026-08-08
diff --git a/DEPLOYMENT.md b/DEPLOYMENT.md
index 05d5d113..d0fde5ad 100644
--- a/DEPLOYMENT.md
+++ b/DEPLOYMENT.md
@@ -134,6 +134,10 @@ Learn substitute-instructor capability URLs are signed bearer links. Configure r
 proxy and access logging to redact their query strings, and use bounded expiration when
 issuing them from Learn.
 
+Learn student waiting-room launches embedded in an LMS use a `Secure; SameSite=None; Partitioned` httpOnly handoff cookie so the ActiveBits iframe can poll its same-origin
+waiting-room status endpoint without requiring a global third-party cookie. Production
+must therefore use HTTPS.
+
 ## Source Map Policy (Open-Source Repo)
 
 ActiveBits intentionally ships source maps in production for debugging and teaching transparency.
diff --git a/activities/syncdeck/server/learnIntegration.test.ts b/activities/syncdeck/server/learnIntegration.test.ts
index c4c6fc52..5e3dfedc 100644
--- a/activities/syncdeck/server/learnIntegration.test.ts
+++ b/activities/syncdeck/server/learnIntegration.test.ts
@@ -110,6 +110,56 @@ void test('buildLearnHmacCanonicalRequest orders object keys by codepoint', () =
   assert.equal(request, `POST\n/path\n123\nnonce\nprovider\n${expectedHash}`)
 })
 
+void test('Learn waiting-room handoff retains local cookie attributes outside production', async () => {
+  const previousSecret = process.env.LEARN_SYNCDECK_HMAC_SECRET
+  const previousKeyId = process.env.LEARN_SYNCDECK_HMAC_KEY_ID
+  const previousNodeEnv = process.env.NODE_ENV
+  process.env.LEARN_SYNCDECK_HMAC_SECRET = 'a test-only Learn integration secret that is long enough'
+  process.env.LEARN_SYNCDECK_HMAC_KEY_ID = 'test-key'
+  process.env.NODE_ENV = 'development'
+
+  try {
+    const getHandlers = new Map<string, RouteHandler>()
+    const postHandlers = new Map<string, RouteHandler>()
+    registerLearnSyncDeckRoutes({
+      app: {
+        get(path, handler) { getHandlers.set(path, handler) },
+        post(path, handler) { postHandlers.set(path, handler) },
+      },
+      sessions: store([]),
+      ws: { wss: { clients: new Set<ActiveBitsWebSocket>(), close() {} }, register() {} },
+      async createInstructorSession() { throw new Error('not used by the waiting-room handoff test') },
+      writeInstructorRecoveryCookie() {},
+    })
+
+    const resourceLinkId = 'learn-resource-non-production-cookie'
+    const entryPath = `/api/integrations/learn/v1/activities/syncdeck/resources/${resourceLinkId}/student-entry`
+    const entryResponse = response()
+    await postHandlers.get('/api/integrations/learn/v1/activities/:activityId/resources/:resourceLinkId/student-entry')!(
+      { params: { activityId: 'syncdeck', resourceLinkId }, ...signedRequest('POST', entryPath, {}, 'non-production-cookie-entry') },
+      entryResponse,
+    )
+    const launchUrl = new URL(String((entryResponse.body as { waitingLaunchUrl: string }).waitingLaunchUrl), 'https://bits.example')
+    const handoffResponse = response()
+    await getHandlers.get('/integrations/learn/:activityId/wait/:tokenId')!(
+      { params: { activityId: 'syncdeck', tokenId: launchUrl.pathname.split('/').at(-1) }, query: { token: launchUrl.searchParams.get('token') } },
+      handoffResponse,
+    )
+    const waitCookie = handoffResponse.cookies.find((item) => item.name === 'learn_syncdeck_wait')
+    assert.equal(waitCookie?.options.maxAge, 10 * 60 * 1000)
+    assert.equal(waitCookie?.options.sameSite, 'lax')
+    assert.equal(waitCookie?.options.secure, false)
+    assert.equal(waitCookie?.options.partitioned, false)
+  } finally {
+    if (previousSecret === undefined) delete process.env.LEARN_SYNCDECK_HMAC_SECRET
+    else process.env.LEARN_SYNCDECK_HMAC_SECRET = previousSecret
+    if (previousKeyId === undefined) delete process.env.LEARN_SYNCDECK_HMAC_KEY_ID
+    else process.env.LEARN_SYNCDECK_HMAC_KEY_ID = previousKeyId
+    if (previousNodeEnv === undefined) delete process.env.NODE_ENV
+    else process.env.NODE_ENV = previousNodeEnv
+  }
+})
+
 void test('Learn identity fingerprints match the documented cross-system vector', () => {
   const secret = 'example-shared-learn-syncdeck-hmac-secret'
   const provider = 'learn-district-42'
@@ -129,12 +179,14 @@ void test('Learn identity fingerprints match the documented cross-system vector'
 void test('Learn routes transition a one-time waiting-room entry into an active SyncDeck session', async () => {
   const previousSecret = process.env.LEARN_SYNCDECK_HMAC_SECRET
   const previousKeyId = process.env.LEARN_SYNCDECK_HMAC_KEY_ID
+  const previousNodeEnv = process.env.NODE_ENV
   const previousInfo = console.info
   const previousError = console.error
   const infoLogs: string[] = []
   const errorLogs: string[] = []
   process.env.LEARN_SYNCDECK_HMAC_SECRET = 'a test-only Learn integration secret that is long enough'
   process.env.LEARN_SYNCDECK_HMAC_KEY_ID = 'test-key'
+  process.env.NODE_ENV = 'production'
   console.info = (...args: unknown[]) => { infoLogs.push(args.map(String).join(' ')) }
   console.error = (...args: unknown[]) => { errorLogs.push(args.map(String).join(' ')) }
   previousInfo('[TEST] Expected Learn integration failure logs are captured by this test.')
@@ -262,7 +314,12 @@ void test('Learn routes transition a one-time waiting-room entry into an active
     assert.equal(waitLaunchResponse.redirectTo, '/integrations/learn/syncdeck/wait')
     assert.equal(waitLaunchResponse.headers['Referrer-Policy'], 'no-referrer')
     const waitCookie = waitLaunchResponse.cookies.find((item) => item.name === 'learn_syncdeck_wait')
+    assert.equal(waitCookie?.options.maxAge, 10 * 60 * 1000)
     assert.equal(waitCookie?.options.path, '/')
+    assert.equal(waitCookie?.options.sameSite, 'none')
+    assert.equal(waitCookie?.options.secure, true)
+    assert.equal(waitCookie?.options.partitioned, true)
+    assert.equal(waitCookie?.options.httpOnly, true)
     const waitingCookie = waitCookie?.value
     assert.ok(waitingCookie)
 
@@ -761,5 +818,7 @@ void test('Learn routes transition a one-time waiting-room entry into an active
     else process.env.LEARN_SYNCDECK_HMAC_SECRET = previousSecret
     if (previousKeyId === undefined) delete process.env.LEARN_SYNCDECK_HMAC_KEY_ID
     else process.env.LEARN_SYNCDECK_HMAC_KEY_ID = previousKeyId
+    if (previousNodeEnv === undefined) delete process.env.NODE_ENV
+    else process.env.NODE_ENV = previousNodeEnv
   }
 })
diff --git a/activities/syncdeck/server/learnIntegration.ts b/activities/syncdeck/server/learnIntegration.ts
index d240560c..e89c7aa8 100644
--- a/activities/syncdeck/server/learnIntegration.ts
+++ b/activities/syncdeck/server/learnIntegration.ts
@@ -960,7 +960,17 @@ export function registerLearnSyncDeckRoutes(options: LearnSyncDeckRouteOptions):
       logLearnRequestFailure('waiting-room-launch', 'invalid-or-expired-browser-launch', { status: 403 })
       return void res.status(403).json({ error: 'Invalid or expired waiting-room launch' })
     }
-    res.cookie?.('learn_syncdeck_wait', cookieValue(key.secret, token.mappingId), { path: '/', httpOnly: true, sameSite: 'lax', secure: process.env.NODE_ENV === 'production' })
+    // Learn launches this route inside an LMS iframe. Production needs a Secure third-party
+    // cookie so the waiting page can send the signed mapping handoff to its same-origin status poll.
+    const isProduction = process.env.NODE_ENV === 'production'
+    res.cookie?.('learn_syncdeck_wait', cookieValue(key.secret, token.mappingId), {
+      maxAge: WAITING_TTL_MS,
+      path: '/',
+      httpOnly: true,
+      sameSite: isProduction ? 'none' : 'lax',
+      secure: isProduction,
+      partitioned: isProduction,
+    })
     if (typeof res.redirect === 'function') return void res.redirect(302, `${BROWSER_PREFIX}/${ACTIVITY_ID}/wait`)
     res.status(302).json({ redirectTo: `${BROWSER_PREFIX}/${ACTIVITY_ID}/wait` })
   })