diff --git a/.github/workflows/validate-idea.yml b/.github/workflows/validate-idea.yml
new file mode 100644
index 00000000..78f929c8
--- /dev/null
+++ b/.github/workflows/validate-idea.yml
@@ -0,0 +1,74 @@
+name: Validate Adventure Idea
+
+# Runs on PRs that touch ideas/*.md.
+# The * glob excludes dot-folders, so ideas/.implemented/ is already filtered
+# by the path pattern. We also filter it explicitly in step 4.
+on:
+  pull_request:
+    paths:
+      - 'ideas/*.md'
+
+jobs:
+  validate:
+    name: Validate idea file format
+    runs-on: ubuntu-latest  # A fresh Ubuntu VM is spun up for each run.
+
+    steps:
+
+      # fetch-depth: 0 is required so git diff can compare against the base branch.
+      - name: Checkout repository
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      # The checkout action does not restore executable bits from git.
+      - name: Make validation script executable
+        run: chmod +x scripts/validate-idea.sh
+
+      # Validates files added or modified by this PR.
+      # Excludes the template and .implemented/ as a belt-and-suspenders
+      # on top of the workflow path filter.
+      # || true prevents grep from failing the step when no files match.
+      - name: Find idea files to validate
+        env:
+          BASE_REF: ${{ github.base_ref }}
+        run: |
+          IDEA_FILES=$(
+            git diff --name-only --diff-filter=AM "origin/$BASE_REF" HEAD \
+            | grep "^ideas/" \
+            | grep "\.md$" \
+            | grep -v "adventure-idea-template.md" \
+            | grep -v "\.implemented/" \
+            || true
+          )
+
+          if [[ -z "$IDEA_FILES" ]]; then
+            echo "No idea files to validate in this PR."
+          else
+            echo "Idea files to validate:"
+            echo "$IDEA_FILES"
+          fi
+
+          {
+            echo "IDEA_FILES<<EOF"
+            echo "$IDEA_FILES"
+            echo "EOF"
+          } >> "$GITHUB_ENV"
+
+      - name: Validate idea files
+        run: |
+          set -euo pipefail
+
+          if [[ -z "$IDEA_FILES" ]]; then
+            echo "No idea files to validate. Skipping."
+            exit 0
+          fi
+
+          while IFS= read -r file; do
+            # Skip blank lines that can appear from the heredoc.
+            [[ -z "$file" ]] && continue
+            ./scripts/validate-idea.sh "$file"
+          done <<< "$IDEA_FILES"
+
+          echo ""
+          echo "✅ All idea files passed validation."
diff --git a/ideas/adventure-idea-template.md b/ideas/adventure-idea-template.md
index 9ee4da79..36b1c83f 100644
--- a/ideas/adventure-idea-template.md
+++ b/ideas/adventure-idea-template.md
@@ -41,7 +41,7 @@
 
 <!-- =========================================================================
   Each level is a standalone challenge. Include Beginner, Intermediate,
-  and/or Expert - delete any you don't need.
+  and/or Expert - delete any level block you don't need.
 
   DIFFICULTY GUIDE:
     🟢 Beginner - First encounter. Solvable in under an hour with just the docs.
diff --git a/lib/scripts/idea-parser.sh b/lib/scripts/idea-parser.sh
new file mode 100644
index 00000000..187a5f20
--- /dev/null
+++ b/lib/scripts/idea-parser.sh
@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+# idea-parser.sh — Shared parsing functions for adventure idea files.
+# Sourced by scripts/validate-idea.sh and scripts/new-adventure.sh.
+#
+# IMPORTANT: The level heading format is enforced here and in both scripts.
+# If you change the format, update this file, adventure-idea-template.md,
+# and any existing idea files in ideas/.
+
+# Expected format for the # Adventure Idea: header line:
+#   # Adventure Idea: EMOJI Adventure Name
+ADVENTURE_HEADER_PATTERN='^# Adventure Idea: \S+ .+'
+
+# Expected format for a ### level heading line (full line including ###):
+#   ### EMOJI DIFFICULTY: Level Name
+LEVEL_HEADING_PATTERN='^### \S+ \S+: .+'
+
+# parse_adventure_header FILE
+# Parses the '# Adventure Idea: EMOJI Name' header line.
+# Sets: adventure_emoji, adventure_name
+parse_adventure_header() {
+  local file="$1"
+  local header
+  header=$(grep -m1 '^# Adventure Idea:' "$file" | sed 's/^# Adventure Idea: *//')
+  adventure_emoji=$(echo "$header" | awk '{print $1}')
+  adventure_name=$(echo "$header" | cut -d' ' -f2-)
+}
+
+# parse_level_heading HEADING
+# Parses a stripped level heading (without leading "### ") into components.
+# Sets: level_emoji, level_difficulty, level_name, level_slug
+parse_level_heading() {
+  local heading="$1"
+  level_emoji=$(echo "$heading" | awk '{print $1}')
+  level_difficulty=$(echo "$heading" | awk '{print $2}' | tr -d ':')
+  level_name=$(echo "$heading" | sed 's/[^ ]* [^:]*: //')
+  level_slug=$(echo "$level_difficulty" | tr '[:upper:]' '[:lower:]')
+}
+
+# extract_overview_field FILE FIELD
+# Prints the content of a **FIELD:** block: any inline text on the same line,
+# plus continuation lines, until the next bold field (**...**) or ## heading.
+extract_overview_field() {
+  local file="$1" field="$2"
+  awk -v field="$field" '
+    $0 ~ ("^\\*\\*" field ":\\*\\*") {
+      sub("^\\*\\*" field ":\\*\\* *", "")
+      if (NF > 0) print
+      in_field = 1
+      next
+    }
+    in_field && (/^\*\*/ || /^##/ || /^---/) { exit }
+    in_field { print }
+  ' "$file"
+}
+
+# extract_level_section FILE LEVEL SECTION
+# Prints the content of a #### subsection within a ### level block.
+extract_level_section() {
+  local file="$1" level="$2" section="$3"
+  awk -v level="$level" -v section="$section" '
+    /^### /  { in_level = ($0 == "### " level); next }
+    in_level && $0 == "#### " section { in_section=1; next }
+    in_level && in_section && (/^#### / || /^---/) { in_section=0 }
+    in_level && in_section { print }
+  ' "$file"
+}
+
+# extract_level_description FILE LEVEL
+# Prints the Description line for a level block.
+extract_level_description() {
+  local file="$1" level="$2"
+  awk -v level="$level" '
+    /^### / { in_level = ($0 == "### " level); in_desc = 0; next }
+    in_level && /^#### / { if (/^#### Description/) { in_desc = 1 } else { in_desc = 0 }; next }
+    in_level && in_desc && NF > 0 { print; exit }
+  ' "$file"
+}
diff --git a/scripts/new-adventure.sh b/scripts/new-adventure.sh
index 84b54a97..3336d150 100755
--- a/scripts/new-adventure.sh
+++ b/scripts/new-adventure.sh
@@ -4,14 +4,15 @@ set -euo pipefail
 REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 IDEAS_DIR="$REPO_ROOT/ideas"
 
+# shellcheck source=../lib/scripts/idea-parser.sh
+source "$REPO_ROOT/lib/scripts/idea-parser.sh"
+
 # ─── Select adventure ────────────────────────────────────────────────────────
 
 selected_slug=$(find "$IDEAS_DIR" -maxdepth 1 -name "*.md" ! -name "adventure-idea-template.md" -exec basename {} .md \; | sort \
   | gum choose --header "Which adventure do you want to scaffold?")
 selected_file="$IDEAS_DIR/$selected_slug.md"
-adventure_header=$(grep -m1 '^# Adventure Idea:' "$selected_file" | sed 's/^# Adventure Idea: *//')
-adventure_emoji=$(echo "$adventure_header" | awk '{print $1}')
-adventure_name=$(echo "$adventure_header" | cut -d' ' -f2-)
+parse_adventure_header "$selected_file"
 
 # ─── Select level ────────────────────────────────────────────────────────────
 
@@ -20,10 +21,7 @@ selected_level=$(echo "$level_lines" | gum choose --header "Which level do you w
 
 # ─── Parse level metadata ─────────────────────────────────────────────────────
 
-level_emoji=$(echo "$selected_level" | awk '{print $1}')
-level_difficulty=$(echo "$selected_level" | awk '{print $2}' | tr -d ':')
-level_name=$(echo "$selected_level" | sed 's/[^ ]* [^:]*: //')
-level_slug=$(echo "$level_difficulty" | tr '[:upper:]' '[:lower:]')
+parse_level_heading "$selected_level"
 
 # position of selected level among ### headings (1st = 01, 2nd = 02, ...)
 level_number=$(echo "$level_lines" \
@@ -38,12 +36,8 @@ echo ""
 # ─── Scaffold adventure base ──────────────────────────────────────────────────
 
 ADVENTURE_DIR="$REPO_ROOT/adventures/planned/00-$selected_slug"
-adventure_technologies=$(grep -m1 '^\*\*Technologies:\*\*' "$selected_file" | sed 's/^\*\*Technologies:\*\* *//')
-adventure_theme=$(awk '
-  /^\*\*Theme:\*\*/ { sub(/^\*\*Theme:\*\* */, ""); p=1; print; next }
-  p && /^\*\*/ { exit }
-  p { print }
-' "$selected_file")
+adventure_technologies=$(extract_overview_field "$selected_file" "Technologies")
+adventure_theme=$(extract_overview_field "$selected_file" "Theme")
 
 if [[ ! -d "$ADVENTURE_DIR" ]]; then
   echo "Creating adventure base at adventures/planned/00-$selected_slug/ ..."
@@ -96,26 +90,11 @@ fi
 
 # ─── Scaffold level doc ───────────────────────────────────────────────────────
 
-# Extracts a #### subsection for the selected level from the idea file
-extract_level_section() {
-  local section="$1"
-  awk -v level="$selected_level" -v section="$section" '
-    /^### /  { in_level = ($0 == "### " level); next }
-    in_level && $0 == "#### " section { in_section=1; next }
-    in_level && in_section && (/^#### / || /^---/) { in_section=0 }
-    in_level && in_section { print }
-  ' "$selected_file"
-}
-
-level_summary=$(awk -v level="$selected_level" '
-  /^### / { in_level = ($0 == "### " level); next }
-  in_level && /^#### Description/ { in_desc = 1; next }
-  in_desc && NF > 0 { print; exit }
-' "$selected_file")
-level_story=$(extract_level_section "Story")
-level_objective=$(extract_level_section "Objective")
-level_learnings=$(extract_level_section "What You'll Learn")
-level_tools=$(extract_level_section "Tools & Infrastructure")
+level_summary=$(extract_level_description "$selected_file" "$selected_level")
+level_story=$(extract_level_section "$selected_file" "$selected_level" "Story")
+level_objective=$(extract_level_section "$selected_file" "$selected_level" "Objective")
+level_learnings=$(extract_level_section "$selected_file" "$selected_level" "What You'll Learn")
+level_tools=$(extract_level_section "$selected_file" "$selected_level" "Tools & Infrastructure")
 
 LEVEL_DOC="$ADVENTURE_DIR/docs/$level_slug.md"
 
diff --git a/scripts/validate-idea.sh b/scripts/validate-idea.sh
new file mode 100755
index 00000000..875b8f9e
--- /dev/null
+++ b/scripts/validate-idea.sh
@@ -0,0 +1,192 @@
+#!/usr/bin/env bash
+# validate-idea.sh — Checks that an adventure idea file follows the required template format.
+#
+# Usage:
+#   ./scripts/validate-idea.sh ideas/my-idea.md
+#
+# Exit codes:
+#   0 — all checks passed
+#   1 — one or more checks failed
+
+# ---------------------------------------------------------------------------
+# Strict mode
+# ---------------------------------------------------------------------------
+# -e is intentionally NOT set — we want all checks to run and collect every
+# failure before exiting, so the contributor sees everything at once.
+set -uo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+# shellcheck source=../lib/scripts/idea-parser.sh
+source "$SCRIPT_DIR/../lib/scripts/idea-parser.sh"
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+ERRORS=()
+
+# fail   — collects a failure; execution continues so all checks run
+# hard_fail — for fatal pre-conditions where continuing makes no sense
+fail() {
+  ERRORS+=("❌ $1")
+}
+
+pass() {
+  echo "✅ $1"
+}
+
+hard_fail() {
+  echo "❌ $1" >&2
+  exit 1
+}
+
+# ---------------------------------------------------------------------------
+# Argument handling
+# ---------------------------------------------------------------------------
+[[ $# -ne 1 ]] && hard_fail "Usage: $0 <path-to-idea-file>"
+
+FILE="$1"
+[[ -f "$FILE" ]] || hard_fail "File not found: $FILE"
+
+echo ""
+echo "Validating: $FILE"
+echo "-------------------------------------------"
+
+# ---------------------------------------------------------------------------
+# Check 1 — File guard
+# ---------------------------------------------------------------------------
+# Block .implemented/ files — they predate the current format and would fail.
+[[ "$FILE" =~ ideas/\.implemented/ ]] \
+  && hard_fail "Skipping already-implemented idea: $FILE"
+
+pass "File guard passed"
+
+# ---------------------------------------------------------------------------
+# Check 2 — Required top-level sections
+# ---------------------------------------------------------------------------
+ERRORS_BEFORE=${#ERRORS[@]}
+
+grep -qE "$ADVENTURE_HEADER_PATTERN" "$FILE" \
+  || fail "Missing or incomplete file header — first line must be: # Adventure Idea: [emoji] [Your Adventure Name]"
+parse_adventure_header "$FILE"
+
+grep -q "^## Overview" "$FILE" \
+  || fail "Missing required section: '## Overview' — use ATX heading style (## Overview), not bold text (**Overview**) or underline-style headings"
+
+grep -q "^## Levels" "$FILE" \
+  || fail "Missing required section: '## Levels' — use ATX heading style (## Levels), not bold text or underline-style headings"
+
+[[ ${#ERRORS[@]} -eq $ERRORS_BEFORE ]] && pass "Required top-level sections present"
+
+# ---------------------------------------------------------------------------
+# Check 3 — Required Overview fields
+# ---------------------------------------------------------------------------
+ERRORS_BEFORE=${#ERRORS[@]}
+
+theme=$(extract_overview_field "$FILE" "Theme")
+printf '%s' "$theme" | grep -q '\S' \
+  || fail "Missing or empty required field: '**Theme:**' — add 2-3 sentences after the field label"
+
+grep -q "^\*\*Skills:\*\*" "$FILE" \
+  || fail "Missing required Overview field: '**Skills:**'"
+
+technologies=$(extract_overview_field "$FILE" "Technologies")
+printf '%s' "$technologies" | grep -q '\S' \
+  || fail "Missing or empty required field: '**Technologies:**' — list the tools on the same line"
+
+[[ ${#ERRORS[@]} -eq $ERRORS_BEFORE ]] && pass "Required Overview fields present"
+
+# ---------------------------------------------------------------------------
+# Check 4 — Level heading format and parseability
+# ---------------------------------------------------------------------------
+# new-adventure.sh parses each ### heading via parse_level_heading() to extract
+# emoji, difficulty, name, and slug. We validate format here AND exercise the
+# same parser so both scripts stay in sync.
+
+ERRORS_BEFORE=${#ERRORS[@]}
+
+if ! grep -q '^### ' "$FILE"; then
+  fail "No level headings found — add at least one '### EMOJI DIFFICULTY: Name' heading under '## Levels'"
+else
+  while IFS= read -r heading; do
+    stripped="${heading#\#\#\# }"
+
+    if echo "$heading" | grep -qE "$LEVEL_HEADING_PATTERN"; then
+      parse_level_heading "$stripped"
+      [[ -n "$level_emoji" ]]      || fail "Could not parse emoji from: '$heading'"
+      [[ -n "$level_difficulty" ]] || fail "Could not parse difficulty from: '$heading'"
+      [[ -n "$level_name" ]]       || fail "Could not parse level name from: '$heading'"
+      [[ -n "$level_slug" ]]       || fail "Could not parse level slug from: '$heading'"
+    else
+      fail "Malformed level heading: '$heading' — expected format: ### 🟢 Beginner: Level Name"
+    fi
+  done < <(grep '^### ' "$FILE")
+fi
+
+[[ ${#ERRORS[@]} -eq $ERRORS_BEFORE ]] && pass "Level heading format valid"
+
+# ---------------------------------------------------------------------------
+# Check 5 — Required subsections present and non-empty for each level
+# ---------------------------------------------------------------------------
+# Checks every level individually so a section missing from one level is caught
+# even if another level has it. Mirrors exactly what new-adventure.sh extracts.
+
+ERRORS_BEFORE=${#ERRORS[@]}
+
+while IFS= read -r heading; do
+  stripped="${heading#\#\#\# }"
+
+  desc=$(extract_level_description "$FILE" "$stripped")
+  [[ -n "$desc" ]] \
+    || fail "Level '$stripped': '#### Description' is missing or has no content"
+
+  for section in "Story" "The Problem" "Objective" "What You'll Learn" "Tools & Infrastructure"; do
+    content=$(extract_level_section "$FILE" "$stripped" "$section")
+    printf '%s' "$content" | grep -q '\S' \
+      || fail "Level '$stripped': '#### $section' is missing or has no content"
+  done
+done < <(grep '^### ' "$FILE")
+
+[[ ${#ERRORS[@]} -eq $ERRORS_BEFORE ]] && pass "All required level sections present"
+
+# ---------------------------------------------------------------------------
+# Check 6 — No unfilled template placeholders (Python one-liner)
+# ---------------------------------------------------------------------------
+# Shell regex can't cleanly distinguish [placeholder] from [link text](url).
+# Python's negative lookahead (?!\() handles this: matches [text] not followed
+# by '(', which filters out Markdown links. [x] and [ ] (checkboxes) are excluded.
+# Skipped for the template file itself, which intentionally contains placeholders.
+
+if [[ "$FILE" != *"adventure-idea-template.md" ]]; then
+
+  ERRORS_BEFORE=${#ERRORS[@]}
+
+  PLACEHOLDER_OUTPUT=$(python3 -c "
+import re, sys
+content = open(sys.argv[1]).read()
+hits = [m for m in re.findall(r'\[([^\]\n]+)\](?!\()', content) if m not in ('x', ' ')]
+if hits:
+    print(' '.join(hits))
+    sys.exit(1)
+" "$FILE") || fail "Unfilled template placeholders — replace: $PLACEHOLDER_OUTPUT"
+
+  [[ ${#ERRORS[@]} -eq $ERRORS_BEFORE ]] && pass "No unfilled template placeholders"
+
+fi
+
+# ---------------------------------------------------------------------------
+# Final summary
+# ---------------------------------------------------------------------------
+echo ""
+if [[ ${#ERRORS[@]} -gt 0 ]]; then
+  echo "Found ${#ERRORS[@]} problem(s) in: $FILE"
+  echo ""
+  for msg in "${ERRORS[@]}"; do
+    echo "  $msg"
+  done
+  echo ""
+  exit 1
+else
+  echo "✅ All checks passed for: $FILE"
+  echo ""
+fi