diff --git a/.github/workflows/release-model-probe.yml b/.github/workflows/release-model-probe.yml
new file mode 100644
index 00000000..727ffa07
--- /dev/null
+++ b/.github/workflows/release-model-probe.yml
@@ -0,0 +1,75 @@
+name: Release Model Probe
+
+on:
+  workflow_dispatch:
+    inputs:
+      commit:
+        description: Exact main commit of the candidate
+        required: true
+        type: string
+      candidate_run_id:
+        description: Successful candidate Release workflow run
+        required: true
+        type: string
+
+concurrency:
+  group: braid-protected-account-proof
+  cancel-in-progress: false
+
+jobs:
+  probe:
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    environment: release-live
+    permissions:
+      actions: read
+      contents: read
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Check out the exact candidate source
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          ref: ${{ inputs.commit }}
+          path: candidate-source
+          fetch-depth: 0
+      - name: Verify candidate source
+        env:
+          REQUESTED_COMMIT: ${{ inputs.commit }}
+        run: |
+          set -euo pipefail
+          test "$(git -C candidate-source rev-parse HEAD)" = "$REQUESTED_COMMIT"
+          test "$(printf '%s' "$REQUESTED_COMMIT" | wc -c)" = 40
+          git -C candidate-source fetch origin main
+          git -C candidate-source merge-base --is-ancestor "$REQUESTED_COMMIT" origin/main
+      - name: Verify the candidate workflow run
+        env:
+          GH_TOKEN: ${{ github.token }}
+          BRAID_RELEASE_RUN_ID: ${{ inputs.candidate_run_id }}
+          BRAID_RELEASE_EXPECT_WORKFLOW: .github/workflows/release.yml
+          BRAID_RELEASE_EXPECT_COMMIT: ${{ inputs.commit }}
+          BRAID_RELEASE_EXPECT_BRANCH: main
+        run: node scripts/release/verify-workflow-run.mjs
+      - name: Download exact candidate
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
+        with:
+          name: braid-release-candidate-${{ inputs.commit }}
+          path: ${{ runner.temp }}/braid-model-probe
+          github-token: ${{ github.token }}
+          run-id: ${{ inputs.candidate_run_id }}
+      - uses: pnpm/action-setup@0ebf47130e4866e96fce0953f49152a61190b271 # v6.0.9
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
+        with:
+          node-version: 22.19.0
+          cache: pnpm
+      - name: Install and build exact candidate source
+        run: |
+          cd candidate-source
+          pnpm install --frozen-lockfile
+          pnpm run build
+      - name: One bounded authenticated Gemini task from installed candidate
+        env:
+          BRAID_LIVE_TANGLE_ENV_JSON: ${{ secrets.BRAID_LIVE_TANGLE_ENV_JSON }}
+          BRAID_PROBE_SOURCE: ${{ github.workspace }}/candidate-source
+          BRAID_PROBE_ARTIFACT_ROOT: ${{ runner.temp }}/braid-model-probe
+          BRAID_PROBE_COMMIT: ${{ inputs.commit }}
+        run: node scripts/release/model-probe.mjs
diff --git a/scripts/release/model-probe.mjs b/scripts/release/model-probe.mjs
new file mode 100644
index 00000000..fa34fd2e
--- /dev/null
+++ b/scripts/release/model-probe.mjs
@@ -0,0 +1,122 @@
+import { readFile, writeFile } from 'node:fs/promises'
+import { join, resolve } from 'node:path'
+
+import { installPackedBraid } from '../packed-binary.mjs'
+import { readCandidateIdentity } from './build-identity.mjs'
+import { connectionConfiguration } from '../live-required/configuration.mjs'
+import { safeMessage } from '../live-required/contracts.mjs'
+import {
+  closeSession,
+  prepareProductionWorkspace,
+  runHeadlessTurn,
+} from '../live-required/headless.mjs'
+
+const model = 'gemini-2.5-flash-lite'
+const marker = 'BRAID_GEMINI_PROBE_OK'
+const source = resolve(process.env.BRAID_PROBE_SOURCE ?? '')
+const artifactRoot = resolve(process.env.BRAID_PROBE_ARTIFACT_ROOT ?? '')
+const commit = process.env.BRAID_PROBE_COMMIT
+const rawSecret = process.env.BRAID_LIVE_TANGLE_ENV_JSON
+if (!/^[a-f0-9]{40}$/u.test(commit ?? '') || !rawSecret) {
+  throw new Error('Exact candidate commit and protected environment are required')
+}
+const protectedEnvironment = JSON.parse(rawSecret)
+if (
+  protectedEnvironment === null ||
+  typeof protectedEnvironment !== 'object' ||
+  Array.isArray(protectedEnvironment)
+) {
+  throw new Error('Protected environment is invalid')
+}
+const environment = { ...process.env, ...protectedEnvironment }
+delete environment.BRAID_LIVE_TANGLE_ENV_JSON
+const values = connectionConfiguration(environment, {
+  prefix: 'BRAID_TANGLE',
+  kind: 'tangle-inference',
+  endpointNames: ['BRAID_TANGLE_INFERENCE_ENDPOINT'],
+  modelNames: ['BRAID_TANGLE_INFERENCE_MODEL'],
+  runnerNames: ['BRAID_TANGLE_INFERENCE_RUNNER'],
+  providerNames: ['BRAID_TANGLE_INFERENCE_PROVIDER'],
+  fallbackModelProvider: 'tangle-router',
+  fallbackRunner: 'cli-base',
+})
+if (values.credentialValue === undefined) {
+  throw new Error('Probe requires the existing protected credential value')
+}
+if (values.modelProvider !== 'tangle-router') {
+  throw new Error('Protected credential is not configured for Tangle Router')
+}
+const catalogUrl = new URL('/v1/models', values.endpoint)
+const auth = values.credentialValue.replace(/^Bearer\s+/iu, '')
+const catalogResponse = await fetch(catalogUrl, {
+  headers: { Authorization: `Bearer ${auth}` },
+  signal: AbortSignal.timeout(10_000),
+})
+if (!catalogResponse.ok) {
+  throw new Error(`Protected credential model listing returned HTTP ${catalogResponse.status}`)
+}
+const catalog = await catalogResponse.json()
+if (!Array.isArray(catalog.data) || !catalog.data.some((item) => item?.id === model)) {
+  throw new Error('Protected credential catalog does not list the selected model')
+}
+const { identity } = await readCandidateIdentity({
+  repository: source,
+  artifactRoot,
+  expectedCommit: commit,
+  expectedVersion: '0.3.4',
+})
+const packed = await installPackedBraid(source, {
+  tarballPath: join(artifactRoot, identity.tarballPath),
+})
+let config
+let session
+try {
+  if (packed.tarballSha256 !== identity.tarballSha256) {
+    throw new Error('Installed archive differs from the candidate')
+  }
+  config = await prepareProductionWorkspace({
+    repository: source,
+    environment,
+    ...values,
+    model,
+  })
+  const profilePath = join(config.workspace, '.braid', 'profiles', 'profile-tangle-inference.json')
+  const profile = JSON.parse(await readFile(profilePath, 'utf8'))
+  profile.model.maxVisibleOutputTokens = 32
+  profile.model.maxTotalOutputTokens = 64
+  await writeFile(profilePath, `${JSON.stringify(profile, null, 2)}\n`, { mode: 0o600 })
+  process.env.BRAID_LIVE_REQUIRED_TIMEOUT_MS = '60000'
+  const turn = await runHeadlessTurn({
+    binary: packed.binary,
+    config,
+    marker,
+    prompt: `Reply with exactly ${marker}.`,
+  })
+  session = turn.session
+  const receipt = {
+    schema: 'braid.release-model-probe.v1',
+    commit,
+    version: identity.braidVersion,
+    tarballSha256: packed.tarballSha256,
+    model: turn.run.model ?? model,
+    status: turn.run.status,
+    runId: turn.run.id,
+    materializationDigest: turn.run.materializationDigest,
+    costStatus: turn.run.costStatus ?? 'unknown',
+    costUsd: turn.run.costUsd ?? null,
+    maxVisibleOutputTokens: 32,
+    maxTotalOutputTokens: 64,
+    markerMatched: true,
+  }
+  process.stdout.write(`${JSON.stringify(receipt)}\n`)
+  if (typeof receipt.costUsd === 'number' && receipt.costUsd > 0.01) {
+    throw new Error('One-turn cost exceeded the $0.01 probe ceiling')
+  }
+} catch (error) {
+  process.stderr.write(`Protected model probe failed: ${safeMessage(error, environment)}\n`)
+  process.exitCode = 1
+} finally {
+  if (session) await closeSession(session)
+  if (config) await config.cleanup()
+  await packed.cleanup()
+}