diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 7d817d0..95f774d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -1,4 +1,4 @@
-name: Tests
+name: Validate Demo
 
 on:
   push:
@@ -7,7 +7,55 @@ on:
 jobs:
   validate:
     runs-on: macos-latest
+    env:
+      BASE_CACHE_DIR: ${{ github.workspace }}/.base-cache
+      BASE_SETUP_NOTIFY: "false"
+      PIP_DISABLE_PIP_VERSION_CHECK: "1"
     steps:
       - uses: actions/checkout@v4
+
+      - name: Install BATS
+        run: brew install bats-core
+
       - name: Validate repository baseline
         run: ./tests/validate.sh
+
+      - name: Run demo script tests
+        run: bats tests/demo_test.bats
+
+      - name: Check out Base
+        run: git clone --depth 1 https://github.com/codeforester/base.git ../base
+
+      - name: Detect Base demo support
+        id: base_demo
+        run: |
+          if ../base/bin/basectl demo --help >/dev/null 2>&1; then
+            echo "supported=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "supported=false" >> "$GITHUB_OUTPUT"
+            echo "Base master does not support basectl demo yet; skipping full Base-backed validation."
+          fi
+
+      - name: Set up Base
+        if: steps.base_demo.outputs.supported == 'true'
+        run: ../base/bin/basectl setup base --no-notify
+
+      - name: Set up base-demo
+        if: steps.base_demo.outputs.supported == 'true'
+        run: ../base/bin/basectl setup base-demo --no-notify
+
+      - name: Check base-demo
+        if: steps.base_demo.outputs.supported == 'true'
+        run: ../base/bin/basectl check base-demo
+
+      - name: Doctor base-demo
+        if: steps.base_demo.outputs.supported == 'true'
+        run: ../base/bin/basectl doctor base-demo
+
+      - name: Test base-demo
+        if: steps.base_demo.outputs.supported == 'true'
+        run: ../base/bin/basectl test base-demo
+
+      - name: Run base-demo non-interactively
+        if: steps.base_demo.outputs.supported == 'true'
+        run: ../base/bin/basectl demo base-demo -- --non-interactive
diff --git a/CHANGELOG.md b/CHANGELOG.md
index d22e91e..208eb10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,3 +12,6 @@ and versions are tracked in the repo-root `VERSION` file.
 - Initialized the repository with the Base-managed repo baseline.
 - Added a Base manifest, Brewfile, activation source, example command, and
   baseline validation script.
+- Added the interactive `basectl demo base-demo` walkthrough and BATS coverage.
+- Expanded GitHub Actions validation for the demo script and Base-backed demo
+  flow.
diff --git a/README.md b/README.md
index c515caa..353e39b 100644
--- a/README.md
+++ b/README.md
@@ -24,6 +24,7 @@ basectl check base-demo
 basectl doctor base-demo
 basectl run base-demo hello
 basectl test base-demo
+basectl demo base-demo
 ```
 
 ## Repository Shape
@@ -33,7 +34,11 @@ basectl test base-demo
 - `Brewfile` is the Homebrew-owned place for ordinary macOS tools.
 - `.base/activate.sh` demonstrates project activation state.
 - `src/hello.sh` is a tiny command target for `basectl run`.
+- `demo/demo.sh` is the interactive walkthrough.
 - `tests/validate.sh` verifies that the repository baseline is intact.
 
-The interactive `basectl demo base-demo` walkthrough lands in a follow-up change
-after the Base demo command is available in a released Base version.
+For CI or scripted validation, run the walkthrough without prompts:
+
+```bash
+basectl demo base-demo -- --non-interactive
+```
diff --git a/base_manifest.yaml b/base_manifest.yaml
index 1f82f54..9600b21 100644
--- a/base_manifest.yaml
+++ b/base_manifest.yaml
@@ -15,4 +15,8 @@ commands:
 test:
   command: ./tests/validate.sh
 
+demo:
+  script: ./demo/demo.sh
+  description: Interactive walkthrough of Base-managed project conventions
+
 artifacts: []
diff --git a/demo/demo.sh b/demo/demo.sh
new file mode 100755
index 0000000..abc945f
--- /dev/null
+++ b/demo/demo.sh
@@ -0,0 +1,188 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+BASE_DEMO_PROJECT="${BASE_PROJECT:-base-demo}"
+BASE_DEMO_ROOT="${BASE_PROJECT_ROOT:-}"
+BASE_DEMO_BASECTL="${BASE_DEMO_BASECTL:-basectl}"
+BASE_DEMO_NON_INTERACTIVE=0
+
+demo_script_dir() {
+  cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P
+}
+
+demo_project_root() {
+  if [[ -n "$BASE_DEMO_ROOT" ]]; then
+    cd -- "$BASE_DEMO_ROOT" && pwd -P
+    return
+  fi
+
+  cd -- "$(demo_script_dir)/.." && pwd -P
+}
+
+BASE_DEMO_ROOT="$(demo_project_root)"
+
+usage() {
+  cat <<'EOF'
+Usage:
+  demo/demo.sh [--non-interactive] [-h|--help]
+
+Run the base-demo interactive walkthrough.
+EOF
+}
+
+parse_args() {
+  while (($#)); do
+    case "$1" in
+      --non-interactive)
+        BASE_DEMO_NON_INTERACTIVE=1
+        ;;
+      -h|--help|help)
+        usage
+        return 2
+        ;;
+      *)
+        printf 'ERROR: Unknown demo option %q\n' "$1" >&2
+        usage >&2
+        return 1
+        ;;
+    esac
+    shift
+  done
+}
+
+pause() {
+  if [[ "$BASE_DEMO_NON_INTERACTIVE" == "1" || ! -t 0 ]]; then
+    return 0
+  fi
+
+  printf '\nPress Enter to continue...'
+  read -r _
+  printf '\n'
+}
+
+step() {
+  printf '\n== Step %s: %s ==\n\n' "$1" "$2"
+}
+
+run_command() {
+  printf '  $'
+  printf ' %q' "$@"
+  printf '\n'
+
+  if ! "$@"; then
+    printf '\nDemo step failed while running the command above.\n' >&2
+    printf 'Run it manually from %s, fix the issue, and retry the demo.\n' "$BASE_DEMO_ROOT" >&2
+    return 1
+  fi
+}
+
+capture_command() {
+  local output
+
+  printf '  $'
+  printf ' %q' "$@"
+  printf '\n'
+
+  if ! output="$("$@" 2>&1)"; then
+    printf '%s\n' "$output" >&2
+    printf '\nDemo step failed while running the command above.\n' >&2
+    return 1
+  fi
+
+  printf '%s\n' "$output"
+}
+
+require_contains() {
+  local label="$1"
+  local output="$2"
+  local expected="$3"
+
+  if [[ "$output" != *"$expected"* ]]; then
+    printf 'ERROR: Expected %s output to contain %q.\n' "$label" "$expected" >&2
+    return 1
+  fi
+}
+
+intro() {
+  printf '\nbase-demo Walkthrough\n\n'
+  printf 'This demo shows the smallest useful Base-managed project shape.\n'
+  printf 'Each step runs a real command or validates a real file in this repo.\n'
+  pause
+}
+
+project_shape_step() {
+  step 1 "Project Shape"
+  run_command test -f "$BASE_DEMO_ROOT/base_manifest.yaml"
+  run_command test -f "$BASE_DEMO_ROOT/Brewfile"
+  run_command test -x "$BASE_DEMO_ROOT/src/hello.sh"
+  run_command test -x "$BASE_DEMO_ROOT/tests/validate.sh"
+  pause
+}
+
+manifest_step() {
+  step 2 "Manifest Contracts"
+  run_command grep -n "name: base-demo" "$BASE_DEMO_ROOT/base_manifest.yaml"
+  run_command grep -n "hello: ./src/hello.sh" "$BASE_DEMO_ROOT/base_manifest.yaml"
+  run_command grep -n "command: ./tests/validate.sh" "$BASE_DEMO_ROOT/base_manifest.yaml"
+  run_command grep -n "script: ./demo/demo.sh" "$BASE_DEMO_ROOT/base_manifest.yaml"
+  pause
+}
+
+activation_step() {
+  step 3 "Project Activation Source"
+  # shellcheck source=/dev/null
+  source "$BASE_DEMO_ROOT/.base/activate.sh"
+  printf 'BASE_DEMO_ENV=%s\n' "${BASE_DEMO_ENV:-unset}"
+  require_contains "activation" "${BASE_DEMO_ENV:-}" "baseline"
+  pause
+}
+
+run_step() {
+  local output
+
+  step 4 "Declared Command"
+  output="$(capture_command "$BASE_DEMO_BASECTL" run "$BASE_DEMO_PROJECT" hello)"
+  printf '%s\n' "$output"
+  require_contains "run command" "$output" "hello from base-demo"
+  pause
+}
+
+test_step() {
+  local output
+
+  step 5 "Test Contract"
+  output="$(capture_command "$BASE_DEMO_BASECTL" test "$BASE_DEMO_PROJECT")"
+  printf '%s\n' "$output"
+  require_contains "test command" "$output" "Repository baseline is present."
+  pause
+}
+
+demo_step() {
+  local output
+
+  step 6 "Demo Contract"
+  output="$(capture_command "$BASE_DEMO_BASECTL" demo "$BASE_DEMO_PROJECT" --dry-run -- --non-interactive)"
+  printf '%s\n' "$output"
+  require_contains "demo command" "$output" "Would run demo"
+  pause
+}
+
+main() {
+  parse_args "$@" || {
+    local status=$?
+    [[ "$status" -eq 2 ]] && return 0
+    return "$status"
+  }
+
+  cd -- "$BASE_DEMO_ROOT"
+  intro
+  project_shape_step
+  manifest_step
+  activation_step
+  run_step
+  test_step
+  demo_step
+  printf '\nbase-demo walkthrough complete.\n'
+}
+
+main "$@"
diff --git a/tests/demo_test.bats b/tests/demo_test.bats
new file mode 100755
index 0000000..8cead60
--- /dev/null
+++ b/tests/demo_test.bats
@@ -0,0 +1,68 @@
+#!/usr/bin/env bats
+
+setup() {
+  TEST_ROOT="$(cd "$BATS_TEST_DIRNAME/.." && pwd -P)"
+  TEST_TMPDIR="$(mktemp -d "${TMPDIR:-/tmp}/base-demo-test.XXXXXX")"
+}
+
+teardown() {
+  rm -rf "$TEST_TMPDIR"
+}
+
+@test "demo script is declared and executable" {
+  grep -Fq "script: ./demo/demo.sh" "$TEST_ROOT/base_manifest.yaml"
+  [ -x "$TEST_ROOT/demo/demo.sh" ]
+}
+
+@test "demo script prints help" {
+  run "$TEST_ROOT/demo/demo.sh" --help
+
+  [ "$status" -eq 0 ]
+  [[ "$output" == *"Run the base-demo interactive walkthrough."* ]]
+}
+
+@test "demo script runs in non-interactive mode" {
+  local fake_bin="$TEST_TMPDIR/bin"
+  local state_file="$TEST_TMPDIR/state"
+
+  mkdir -p "$fake_bin"
+  cat > "$fake_bin/basectl" <<'EOF'
+#!/usr/bin/env bash
+printf 'basectl %s\n' "$*" >> "${BASE_DEMO_TEST_STATE:?}"
+case "$*" in
+  run\ base-demo\ hello)
+    printf 'hello from base-demo\n'
+    printf 'BASE_PROJECT=base-demo\n'
+    printf 'BASE_DEMO_ENV=%s\n' "${BASE_DEMO_ENV:-unset}"
+    ;;
+  test\ base-demo)
+    printf 'Repository baseline is present.\n'
+    ;;
+  demo\ base-demo\ --dry-run\ --\ --non-interactive)
+    printf '[DRY-RUN] Would run demo for project base-demo.\n'
+    ;;
+  *)
+    printf 'unexpected basectl args: %s\n' "$*" >&2
+    exit 1
+    ;;
+esac
+EOF
+  chmod +x "$fake_bin/basectl"
+
+  run env \
+    BASE_PROJECT=base-demo \
+    BASE_PROJECT_ROOT="$TEST_ROOT" \
+    BASE_DEMO_BASECTL="$fake_bin/basectl" \
+    BASE_DEMO_TEST_STATE="$state_file" \
+    "$TEST_ROOT/demo/demo.sh" --non-interactive
+
+  [ "$status" -eq 0 ]
+  [[ "$output" == *"base-demo Walkthrough"* ]]
+  [[ "$output" == *"BASE_DEMO_ENV=baseline"* ]]
+  [[ "$output" == *"hello from base-demo"* ]]
+  [[ "$output" == *"Repository baseline is present."* ]]
+  [[ "$output" == *"base-demo walkthrough complete."* ]]
+  grep -Fqx "basectl run base-demo hello" "$state_file"
+  grep -Fqx "basectl test base-demo" "$state_file"
+  grep -Fqx "basectl demo base-demo --dry-run -- --non-interactive" "$state_file"
+}
diff --git a/tests/validate.sh b/tests/validate.sh
index 8514328..239b876 100755
--- a/tests/validate.sh
+++ b/tests/validate.sh
@@ -11,6 +11,8 @@ required_files=(
   Brewfile
   .base/activate.sh
   src/hello.sh
+  demo/demo.sh
+  tests/demo_test.bats
   .github/workflows/tests.yml
 )
 
@@ -21,7 +23,7 @@ for file in "${required_files[@]}"; do
   }
 done
 
-for executable in tests/validate.sh .base/activate.sh src/hello.sh; do
+for executable in tests/validate.sh .base/activate.sh src/hello.sh demo/demo.sh; do
   [[ -x "$executable" ]] || {
     printf 'Required file is not executable: %s\n' "$executable" >&2
     exit 1
@@ -48,4 +50,9 @@ grep -Fq 'hello: ./src/hello.sh' base_manifest.yaml || {
   exit 1
 }
 
+grep -Fq 'script: ./demo/demo.sh' base_manifest.yaml || {
+  printf 'base_manifest.yaml does not declare the demo script.\n' >&2
+  exit 1
+}
+
 printf 'Repository baseline is present.\n'