diff --git a/.github/workflows/post-to-discourse/action.yml b/.github/workflows/post-to-discourse/action.yml
deleted file mode 100644
index 55232ce0e1..0000000000
--- a/.github/workflows/post-to-discourse/action.yml
+++ /dev/null
@@ -1,105 +0,0 @@
-name: 'Post to Discourse'
-description: 'Posts a message to a Discourse topic (existing or new)'
-
-inputs:
-  discourse-url:
-    description: 'Discourse instance URL (e.g., https://discourse.example.com)'
-    required: true
-  api-key:
-    description: 'Discourse API key'
-    required: true
-  api-username:
-    description: 'Discourse API username'
-    required: true
-  topic-id:
-    description: 'Discourse topic ID to post to (use this OR category-id + title)'
-    required: false
-  category-id:
-    description: 'Category ID for new topic (required if topic-id not provided)'
-    required: false
-  title:
-    description: 'Title for new topic (required if topic-id not provided)'
-    required: false
-  message:
-    description: 'Message content (markdown supported)'
-    required: true
-
-outputs:
-  post-number:
-    description: 'The post number in the topic'
-    value: ${{ steps.post.outputs.post_number }}
-  post-url:
-    description: 'Direct URL to the post'
-    value: ${{ steps.post.outputs.post_url }}
-  topic-id:
-    description: 'The topic ID (useful when creating a new topic)'
-    value: ${{ steps.post.outputs.topic_id }}
-
-runs:
-  using: "composite"
-  steps:
-    - name: Post to Discourse
-      id: post
-      shell: bash
-      run: |
-        # Validate inputs
-        if [ -z "${{ inputs.topic-id }}" ] && ([ -z "${{ inputs.category-id }}" ] || [ -z "${{ inputs.title }}" ]); then
-          echo "❌ Error: Must provide either topic-id OR both category-id and title"
-          exit 1
-        fi
-        
-        if [ -n "${{ inputs.topic-id }}" ] && ([ -n "${{ inputs.category-id }}" ] || [ -n "${{ inputs.title }}" ]); then
-          echo "⚠️  Warning: Both topic-id and category-id/title provided. Will post to existing topic."
-        fi
-        
-        # Determine if creating new topic or posting to existing
-        if [ -n "${{ inputs.topic-id }}" ]; then
-          echo "📝 Posting to existing topic ID: ${{ inputs.topic-id }}"
-        
-          # Create JSON payload for posting to existing topic
-          PAYLOAD=$(jq -n \
-            --arg content '${{ inputs.message }}' \
-            --arg topic_id "${{ inputs.topic-id }}" \
-            '{topic_id: $topic_id, raw: $content}')
-        else
-          echo "✨ Creating new topic: ${{ inputs.title }}"
-        
-          # Create JSON payload for new topic
-          PAYLOAD=$(jq -n \
-            --arg content '${{ inputs.message }}' \
-            --arg title "${{ inputs.title }}" \
-            --arg category "${{ inputs.category-id }}" \
-            '{title: $title, category: ($category | tonumber), raw: $content}')
-        fi
-        
-        # Post to Discourse
-        RESPONSE=$(curl -s -w "\n%{http_code}" \
-          -X POST "${{ inputs.discourse-url }}/posts.json" \
-          -H "Content-Type: application/json" \
-          -H "Api-Key: ${{ inputs.api-key }}" \
-          -H "Api-Username: ${{ inputs.api-username }}" \
-          -d "$PAYLOAD")
-        
-        HTTP_CODE=$(echo "$RESPONSE" | tail -n1)
-        BODY=$(echo "$RESPONSE" | sed '$d')
-        
-        if [ "$HTTP_CODE" -ge 200 ] && [ "$HTTP_CODE" -lt 300 ]; then
-          echo "✅ Successfully posted to Discourse!"
-        
-          POST_NUMBER=$(echo "$BODY" | jq -r '.post_number // "unknown"')
-          TOPIC_ID=$(echo "$BODY" | jq -r '.topic_id // "${{ inputs.topic-id }}"')
-          POST_URL="${{ inputs.discourse-url }}/t/${TOPIC_ID}/${POST_NUMBER}"
-        
-          echo "post_number=${POST_NUMBER}" >> $GITHUB_OUTPUT
-          echo "post_url=${POST_URL}" >> $GITHUB_OUTPUT
-          echo "topic_id=${TOPIC_ID}" >> $GITHUB_OUTPUT
-        
-          echo "Topic ID: ${TOPIC_ID}"
-          echo "Post number: ${POST_NUMBER}"
-          echo "URL: ${POST_URL}"
-        else
-          echo "❌ Failed to post to Discourse"
-          echo "HTTP Code: ${HTTP_CODE}"
-          echo "Response: ${BODY}"
-          exit 1
-        fi
\ No newline at end of file
diff --git a/.github/workflows/sync-docs-discourse.yml b/.github/workflows/sync-docs-discourse.yml
new file mode 100644
index 0000000000..56d9f22160
--- /dev/null
+++ b/.github/workflows/sync-docs-discourse.yml
@@ -0,0 +1,89 @@
+name: Sync Docs to Discourse
+
+on:
+  push:
+    paths:
+      - "docs_sp/**"
+      - "zensical.toml"
+  pull_request:
+    paths:
+      - "docs_sp/**"
+      - "zensical.toml"
+  workflow_dispatch:
+
+jobs:
+  smoke-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install uv
+        run: pip install uv
+
+      - name: Smoke test - post one doc to Discourse
+        env:
+          DISCOURSE_URL: ${{ secrets.DISCOURSE_URL }}
+          DISCOURSE_API_KEY: ${{ secrets.DISCOURSE_API_KEY }}
+          DISCOURSE_API_USER: ${{ secrets.DISCOURSE_API_USER }}
+        run: |
+          uv run --python 3.12 -c "
+          import sys
+          sys.path.insert(0, 'docs_sp/tools')
+          from pathlib import Path
+          from converter import convert
+          from discourse_client import DiscourseClient, DiscourseConfig
+
+          DOCS_BASE_URL = 'https://docs.sunnypilot.ai'
+          DOC_PATH = 'getting-started/what-is-sunnypilot.md'
+
+          raw = (Path('docs_sp') / DOC_PATH).read_text()
+          body = convert(raw, file_path=DOC_PATH, docs_base_url=DOCS_BASE_URL)
+
+          # Append sync metadata
+          docs_url = f'{DOCS_BASE_URL}/{DOC_PATH.replace(\".md\", \"/\")}'
+          body = body.rstrip('\n') + f'\n\n---\n:link: [View on docs site]({docs_url})\n\n<!-- docs-sync-id: {DOC_PATH} -->\n'
+
+          # Extract title from front matter or first heading
+          title = None
+          for line in raw.splitlines():
+              s = line.strip()
+              if s.startswith('title:'):
+                  title = s[len('title:'):].strip().strip('\"').strip(\"'\")
+                  break
+              if s.startswith('# '):
+                  title = s[2:].strip()
+                  break
+          title = f'{title or \"What is sunnypilot?\"} - sunnypilot Docs'
+
+          print(f'Title: {title}')
+          print(f'Body: {len(body)} chars')
+
+          config = DiscourseConfig.from_env()
+          client = DiscourseClient(config)
+
+          cat_id = client.get_category_id()
+          if cat_id is None:
+              print(f'ERROR: Category not found on {config.base_url}')
+              sys.exit(1)
+
+          existing = client.find_topic_by_sync_id(DOC_PATH)
+          if existing is not None:
+              topic_id = existing['id']
+              post_id = client.first_post_id(topic_id)
+              if post_id is None:
+                  print(f'ERROR: No first post for topic {topic_id}')
+                  sys.exit(1)
+              result = client.update_post(post_id, body, edit_reason='CI smoke test')
+              if result is None:
+                  print('ERROR: Failed to update post')
+                  sys.exit(1)
+              print(f'Updated: {config.base_url}/t/{topic_id}')
+          else:
+              result = client.create_topic(title=title, raw=body, category_id=cat_id, tags=['docs-auto-sync'])
+              if result is None:
+                  print('ERROR: Failed to create topic')
+                  sys.exit(1)
+              print(f'Created: {config.base_url}/t/{result.get(\"topic_id\", \"?\")}')
+
+          print('Smoke test passed!')
+          "
diff --git a/.github/workflows/test-discourse.yaml.yml b/.github/workflows/test-discourse.yaml.yml
deleted file mode 100644
index fadaec4eaa..0000000000
--- a/.github/workflows/test-discourse.yaml.yml
+++ /dev/null
@@ -1,78 +0,0 @@
-name: Debug Discourse Posting
-
-on:
-  push:
-
-jobs:
-  test-discourse-post:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-
-      - name: Post test message to Discourse
-        uses: ./.github/workflows/post-to-discourse
-        with:
-          discourse-url: ${{ vars.DISCOURSE_URL }}
-          api-key: ${{ secrets.DISCOURSE_API_KEY }}
-          api-username: ${{ secrets.DISCOURSE_API_USERNAME }}
-          topic-id: ${{ vars.DISCOURSE_UPDATES_TOPIC_ID }}
-          message: |
-            ## 🧪 Test Post from GitHub Actions
-            
-            **This is a test post to verify Discourse integration**
-            
-            - **Workflow**: ${{ github.workflow }}
-            - **Run Number**: #${{ github.run_number }}
-            - **Branch**: `${{ github.ref_name }}`
-            - **Commit**: ${{ github.sha }}
-            - **Actor**: @${{ github.actor }}
-            - **Timestamp**: ${{ github.event.head_commit.timestamp }}
-            
-            ---
-            
-            ### Fake Build Info (for testing)
-            - **Version**: 0.9.8-test
-            - **Build**: #42
-            - **Branch**: release-test
-            
-            [View workflow run](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})
-            
-            *This is an automated test message. Drive safe! 🚗💨*
-      
-      
-      - name: Create topic on Discourse
-        uses: ./.github/workflows/post-to-discourse
-        with:
-          discourse-url: ${{ vars.DISCOURSE_URL }}
-          api-key: ${{ secrets.DISCOURSE_API_KEY }}
-          api-username: ${{ secrets.DISCOURSE_API_USERNAME }}
-          #topic-id: ${{ vars.DISCOURSE_UPDATES_TOPIC_ID }}
-          category-id: 4
-          title: "This is a test of a new topic instead of a reply"
-          message: |
-            ## 🧪 Test Post from GitHub Actions
-            
-            **This is a test post to verify Discourse integration**
-            
-            - **Workflow**: ${{ github.workflow }}
-            - **Run Number**: #${{ github.run_number }}
-            - **Branch**: `${{ github.ref_name }}`
-            - **Commit**: ${{ github.sha }}
-            - **Actor**: @${{ github.actor }}
-            - **Timestamp**: ${{ github.event.head_commit.timestamp }}
-            
-            ---
-            
-            ### Fake Build Info (for testing)
-            - **Version**: 0.9.8-test
-            - **Build**: #42
-            - **Branch**: release-test
-            
-            [View workflow run](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})
-            
-            *This is an automated test message. Drive safe! 🚗💨*
-      - name: Display results
-        if: always()
-        run: |
-          echo "::notice::Discourse post test completed"
-          echo "Check your Discourse topic to verify the post appeared correctly"
\ No newline at end of file
diff --git a/docs_sp/tools/content_cache.py b/docs_sp/tools/content_cache.py
new file mode 100644
index 0000000000..d5280cdf43
--- /dev/null
+++ b/docs_sp/tools/content_cache.py
@@ -0,0 +1,58 @@
+"""SHA-256 content cache for skipping unchanged docs on re-sync.
+
+Stores one .sha256 file per doc in .discourse_sync_cache/. On re-run,
+compares the current file hash against the cached hash to determine
+whether the doc needs syncing.
+"""
+
+from __future__ import annotations
+
+import hashlib
+from pathlib import Path
+
+DEFAULT_CACHE_DIR = Path(__file__).resolve().parent.parent.parent / ".discourse_sync_cache"
+
+
+class ContentCache:
+    """File-based SHA-256 content cache."""
+
+    def __init__(self, cache_dir: str | Path = DEFAULT_CACHE_DIR) -> None:
+        self._cache_dir = Path(cache_dir)
+
+    @property
+    def cache_dir(self) -> Path:
+        return self._cache_dir
+
+    @staticmethod
+    def compute_hash(content: str) -> str:
+        """Compute SHA-256 hex digest of content."""
+        return hashlib.sha256(content.encode("utf-8")).hexdigest()
+
+    def _cache_path(self, doc_path: str) -> Path:
+        """Map a doc path (e.g. 'features/cruise/icbm.md') to its cache file."""
+        slug = doc_path.replace("/", "_").replace(".md", "")
+        return self._cache_dir / f"{slug}.sha256"
+
+    def is_changed(self, doc_path: str, content: str) -> bool:
+        """Return True if content differs from the cached hash (or no cache exists)."""
+        content_hash = self.compute_hash(content)
+        cached = self._cache_path(doc_path)
+        if not cached.exists():
+            return True
+        return cached.read_text().strip() != content_hash
+
+    def save(self, doc_path: str, content: str) -> None:
+        """Save the SHA-256 hash of content to the cache file."""
+        content_hash = self.compute_hash(content)
+        self._cache_dir.mkdir(parents=True, exist_ok=True)
+        self._cache_path(doc_path).write_text(content_hash + "\n")
+
+    def clear(self) -> int:
+        """Remove all cached hashes. Returns the number of files removed."""
+        if not self._cache_dir.exists():
+            return 0
+        count = 0
+        for f in self._cache_dir.glob("*.sha256"):
+            f.unlink()
+            count += 1
+        return count
diff --git a/docs_sp/tools/converter.py b/docs_sp/tools/converter.py
new file mode 100644
index 0000000000..38ddc6ee59
--- /dev/null
+++ b/docs_sp/tools/converter.py
@@ -0,0 +1,281 @@
+"""MkDocs Material -> Discourse-compatible Markdown converter.
+
+Converts MkDocs Material syntax to Discourse-friendly markdown:
+1. Strip YAML front matter
+2. Convert admonitions (!!!/???/???+) to Discourse callouts (> [!TYPE])
+3. Convert Material tabs (=== "Tab Name") to bold headings + ---
+4. Strip grid card HTML (<div class="grid cards" markdown>)
+5. Convert Material emoji shortcodes (:material-*:) to Unicode or strip
+6. Resolve internal .md links to docs site URLs
+7. Clean up excessive blank lines
+"""
+
+from __future__ import annotations
+
+import os
+import re
+from pathlib import Path
+
+DOCS_BASE_URL = os.environ.get("DOCS_BASE_URL", "https://docs.sunnypilot.ai")
+
+ADMONITION_MAP: dict[str, str] = {
+    "note": "NOTE",
+    "abstract": "ABSTRACT",
+    "info": "INFO",
+    "tip": "TIP",
+    "success": "SUCCESS",
+    "question": "QUESTION",
+    "warning": "WARNING",
+    "failure": "FAILURE",
+    "danger": "DANGER",
+    "bug": "BUG",
+    "example": "EXAMPLE",
+    "quote": "QUOTE",
+}
+
+EMOJI_MAP: dict[str, str] = {
+    ":material-rocket-launch:": "",
+    ":material-cog:": "",
+    ":material-car:": "",
+    ":material-shield:": "",
+    ":material-download:": "",
+    ":material-check:": "Y",
+    ":material-close:": "N",
+    ":material-alert:": "!",
+    ":material-information:": "i",
+    ":material-help-circle:": "?",
+    ":material-star:": "*",
+    ":material-link:": "",
+    ":material-eye:": "",
+    ":material-map:": "",
+    ":material-wifi:": "",
+    ":material-cellphone:": "",
+    ":material-steering:": "",
+    ":material-speedometer:": "",
+}
+
+_ADMONITION_RE = re.compile(r"^(\s*)(!{3}|\?{3}\+?)\s+(\w+)(?:\s+\"([^\"]*)\")?\s*$")
+_TAB_RE = re.compile(r'^(\s*)===\s+"([^"]+)"\s*$')
+_FRONT_MATTER_RE = re.compile(r"\A---\n.*?\n---\n*", re.DOTALL)
+_GRID_CARD_OPEN_RE = re.compile(r'<div\s+class="grid\s+cards"\s*(?:markdown)?\s*>')
+_GRID_CARD_CLOSE_RE = re.compile(r"</div>")
+_INTERNAL_LINK_RE = re.compile(r"\]\(([^)]+\.md(?:#[^)]*)?)\)")
+_EMOJI_SHORTCODE_RE = re.compile(r":material-[\w-]+:")
+_EXCESSIVE_BLANKS_RE = re.compile(r"\n{4,}")
+
+
+def convert(content: str, *, file_path: str, docs_base_url: str | None = None) -> str:
+    """Convert MkDocs Material markdown to Discourse-compatible markdown.
+
+    Args:
+        content: Raw markdown content.
+        file_path: Path to the source file (relative to docs_sp/ or absolute).
+            Used for resolving relative internal links.
+        docs_base_url: Base URL for the docs site. Defaults to DOCS_BASE_URL env var.
+
+    Returns:
+        Converted markdown string.
+    """
+    base_url = docs_base_url or DOCS_BASE_URL
+    result = content
+
+    result = strip_front_matter(result)
+    result = convert_admonitions(result)
+    result = convert_tabs(result)
+    result = convert_grid_cards(result)
+    result = convert_emoji_shortcodes(result)
+    result = resolve_internal_links(result, file_path=file_path, docs_base_url=base_url)
+    result = clean_blank_lines(result)
+
+    return result.strip() + "\n"
+
+
+def strip_front_matter(content: str) -> str:
+    """Remove YAML front matter (--- ... ---) from the start of content."""
+    return _FRONT_MATTER_RE.sub("", content)
+
+
+def convert_admonitions(content: str) -> str:
+    """Convert MkDocs admonitions to Discourse/Obsidian callouts.
+
+    Input:
+        !!! warning "Title"
+            Content line 1
+            Content line 2
+
+    Output:
+        > [!WARNING] Title
+        > Content line 1
+        > Content line 2
+    """
+    lines = content.splitlines(keepends=True)
+    result: list[str] = []
+    i = 0
+
+    while i < len(lines):
+        line = lines[i]
+        m = _ADMONITION_RE.match(line)
+
+        if m:
+            indent = m.group(1)
+            marker = m.group(2)
+            ad_type = m.group(3).lower()
+            title = m.group(4)
+
+            callout_type = ADMONITION_MAP.get(ad_type, ad_type.upper())
+
+            header = f"{indent}> [!{callout_type}]"
+            if title:
+                header += f" {title}"
+
+            if marker.startswith("???"):
+                collapsed = "+" not in marker
+                if not title:
+                    action = "expand" if collapsed else "collapse"
+                    header += f" *(click to {action})*"
+
+            result.append(header + "\n")
+            i += 1
+
+            content_indent = indent + "    "
+            while i < len(lines):
+                content_line = lines[i]
+                if content_line.startswith(content_indent):
+                    stripped = content_line[len(content_indent):]
+                    result.append(f"{indent}> {stripped}")
+                    i += 1
+                elif content_line.strip() == "":
+                    # Check if blank line is internal to the admonition
+                    j = i + 1
+                    while j < len(lines) and lines[j].strip() == "":
+                        j += 1
+                    if j < len(lines) and lines[j].startswith(content_indent):
+                        result.append(f"{indent}>\n")
+                        i += 1
+                    else:
+                        break
+                else:
+                    break
+        else:
+            result.append(line)
+            i += 1
+
+    return "".join(result)
+
+
+def convert_tabs(content: str) -> str:
+    """Convert Material tabs to bold headings with horizontal rules.
+
+    Input:
+        === "Tab Name"
+            Content
+
+    Output:
+        **Tab Name**
+
+        Content
+
+        ---
+    """
+    lines = content.splitlines(keepends=True)
+    result: list[str] = []
+    i = 0
+
+    while i < len(lines):
+        line = lines[i]
+        m = _TAB_RE.match(line)
+
+        if m:
+            indent = m.group(1)
+            tab_name = m.group(2)
+
+            result.append(f"{indent}**{tab_name}**\n")
+            result.append("\n")
+            i += 1
+
+            content_indent = indent + "    "
+            while i < len(lines):
+                content_line = lines[i]
+                if content_line.startswith(content_indent) or content_line.strip() == "":
+                    if content_line.strip() == "":
+                        result.append("\n")
+                    else:
+                        stripped = content_line[len(content_indent):]
+                        result.append(f"{indent}{stripped}")
+                    i += 1
+                else:
+                    break
+
+            # Ensure blank line before the horizontal rule
+            if result and result[-1] != "\n":
+                result.append("\n")
+            result.append(f"{indent}---\n")
+            result.append("\n")
+        else:
+            result.append(line)
+            i += 1
+
+    return "".join(result)
+
+
+def convert_grid_cards(content: str) -> str:
+    """Strip grid card HTML wrappers (Discourse doesn't support them)."""
+    result = _GRID_CARD_OPEN_RE.sub("", content)
+    result = _GRID_CARD_CLOSE_RE.sub("", result)
+    return result
+
+
+def convert_emoji_shortcodes(content: str) -> str:
+    """Convert Material emoji shortcodes to plain text equivalents."""
+    result = content
+    for shortcode, replacement in EMOJI_MAP.items():
+        result = result.replace(shortcode, replacement)
+    # Strip any remaining :material-*: shortcodes not in the map
+    result = _EMOJI_SHORTCODE_RE.sub("", result)
+    return result
+
+
+def resolve_internal_links(
+    content: str, *, file_path: str, docs_base_url: str
+) -> str:
+    """Resolve internal .md links to docs site URLs.
+
+    Converts: [text](../features/icbm.md) -> [text](https://docs.sunnypilot.ai/features/icbm/)
+    Converts: [text](../features/icbm.md#section) -> [text](https://docs.sunnypilot.ai/features/icbm/#section)
+    """
+    current_dir = str(Path(file_path).parent)
+
+    def _replace_link(match: re.Match[str]) -> str:
+        raw_path = match.group(1)
+        # Skip external URLs
+        if raw_path.startswith("http"):
+            return match.group(0)
+
+        # Split path and optional anchor
+        anchor = ""
+        if "#" in raw_path:
+            raw_path, anchor = raw_path.rsplit("#", 1)
+            anchor = f"#{anchor}"
+
+        # Resolve relative path from current file's directory
+        resolved = Path(current_dir, raw_path).resolve()
+        resolved_str = str(resolved)
+
+        # Extract docs-relative path
+        docs_sp_idx = resolved_str.find("docs_sp/")
+        if docs_sp_idx >= 0:
+            docs_relative = resolved_str[docs_sp_idx + len("docs_sp/"):]
+        else:
+            # Fallback: use the resolved path relative to file
+            docs_relative = raw_path
+
+        # Convert to URL: remove .md, add trailing slash
+        url_path = re.sub(r"\.md$", "/", docs_relative)
+        return f"]({docs_base_url}/{url_path}{anchor})"
+
+    return _INTERNAL_LINK_RE.sub(_replace_link, content)
+
+
+def clean_blank_lines(content: str) -> str:
+    """Collapse 4+ consecutive blank lines down to 3."""
+    return _EXCESSIVE_BLANKS_RE.sub("\n\n\n", content)
diff --git a/docs_sp/tools/discourse_client.py b/docs_sp/tools/discourse_client.py
new file mode 100644
index 0000000000..d04412d783
--- /dev/null
+++ b/docs_sp/tools/discourse_client.py
@@ -0,0 +1,217 @@
+"""Minimal Discourse API client using only urllib (zero external deps).
+
+Provides the 5 CRUD operations needed by the docs sync orchestrator:
+1. get_category_id(slug)
+2. find_topic_by_sync_id(sync_id)
+3. create_topic(title, raw, category_id, tags)
+4. update_post(post_id, raw, edit_reason)
+5. first_post_id(topic_id)
+
+Configuration via environment variables:
+  DISCOURSE_URL      - Base URL (e.g. https://community.sunnypilot.ai)
+  DISCOURSE_API_KEY  - API key with topic create/update permissions
+  DISCOURSE_API_USER - Username for API requests (default: "system")
+  DISCOURSE_CATEGORY - Category slug for documentation (default: "documentation")
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import urllib.error
+import urllib.parse
+import urllib.request
+from dataclasses import dataclass
+from typing import Any
+
+
+@dataclass(frozen=True)
+class DiscourseConfig:
+    """Immutable configuration for the Discourse API client."""
+
+    base_url: str
+    api_key: str
+    api_user: str = "system"
+    category_slug: str = "documentation"
+
+    @classmethod
+    def from_env(cls) -> DiscourseConfig:
+        """Build config from environment variables.
+
+        Raises:
+            ValueError: If required env vars are missing.
+        """
+        base_url = os.environ.get("DISCOURSE_URL", "")
+        api_key = os.environ.get("DISCOURSE_API_KEY", "")
+
+        if not base_url:
+            raise ValueError("DISCOURSE_URL environment variable is required")
+        if not api_key:
+            raise ValueError("DISCOURSE_API_KEY environment variable is required")
+
+        return cls(
+            base_url=base_url.rstrip("/"),
+            api_key=api_key,
+            api_user=os.environ.get("DISCOURSE_API_USER", "system"),
+            category_slug=os.environ.get("DISCOURSE_CATEGORY", "documentation"),
+        )
+
+
+class DiscourseClient:
+    """Discourse API client for docs sync operations."""
+
+    def __init__(self, config: DiscourseConfig) -> None:
+        self._config = config
+
+    @property
+    def config(self) -> DiscourseConfig:
+        return self._config
+
+    # ----- Public API -----
+
+    def get_category_id(self, slug: str | None = None) -> int | None:
+        """Look up a category ID by slug.
+
+        Args:
+            slug: Category slug. Defaults to config.category_slug.
+
+        Returns:
+            Category ID, or None if not found.
+        """
+        slug = slug or self._config.category_slug
+        data = self._get(f"/c/{slug}/show.json")
+        if data is None:
+            return None
+        return data.get("category", {}).get("id")
+
+    def find_topic_by_sync_id(self, sync_id: str) -> dict[str, Any] | None:
+        """Find an existing topic by its embedded sync ID comment.
+
+        Searches for topics containing <!-- docs-sync-id: {sync_id} -->.
+
+        Args:
+            sync_id: The doc path used as sync identifier.
+
+        Returns:
+            Topic dict with at least 'id' key, or None if not found.
+        """
+        query = f"<!-- docs-sync-id: {sync_id} -->"
+        encoded = urllib.parse.urlencode({"q": query})
+        data = self._get(f"/search.json?{encoded}")
+        if data is None:
+            return None
+        topics = data.get("topics", [])
+        return topics[0] if topics else None
+
+    def create_topic(
+        self,
+        title: str,
+        raw: str,
+        category_id: int,
+        tags: list[str] | None = None,
+    ) -> dict[str, Any] | None:
+        """Create a new topic in the specified category.
+
+        Args:
+            title: Topic title.
+            raw: Markdown body content.
+            category_id: Discourse category ID.
+            tags: Optional list of tags.
+
+        Returns:
+            Response dict with 'topic_id', 'id' (post ID), etc., or None on failure.
+        """
+        payload: dict[str, Any] = {
+            "title": title,
+            "raw": raw,
+            "category": category_id,
+        }
+        if tags:
+            payload["tags"] = tags
+        return self._post("/posts.json", payload)
+
+    def update_post(
+        self,
+        post_id: int,
+        raw: str,
+        edit_reason: str = "Documentation sync",
+    ) -> dict[str, Any] | None:
+        """Update an existing post's content.
+
+        Args:
+            post_id: The Discourse post ID to update.
+            raw: New markdown body content.
+            edit_reason: Reason shown in edit history.
+
+        Returns:
+            Response dict, or None on failure.
+        """
+        payload = {
+            "post": {
+                "raw": raw,
+                "edit_reason": edit_reason,
+            },
+        }
+        return self._put(f"/posts/{post_id}.json", payload)
+
+    def first_post_id(self, topic_id: int) -> int | None:
+        """Get the first post ID of a topic.
+
+        Args:
+            topic_id: The Discourse topic ID.
+
+        Returns:
+            Post ID of the first post, or None if not found.
+        """
+        data = self._get(f"/t/{topic_id}.json")
+        if data is None:
+            return None
+        posts = data.get("post_stream", {}).get("posts", [])
+        if not posts:
+            return None
+        return posts[0].get("id")
+
+    # ----- HTTP helpers -----
+
+    def _headers(self) -> dict[str, str]:
+        return {
+            "Content-Type": "application/json",
+            "Api-Key": self._config.api_key,
+            "Api-Username": self._config.api_user,
+        }
+
+    def _get(self, path: str) -> dict[str, Any] | None:
+        url = self._config.base_url + path
+        req = urllib.request.Request(url, headers=self._headers(), method="GET")
+        return self._send(req)
+
+    def _post(self, path: str, payload: dict[str, Any]) -> dict[str, Any] | None:
+        url = self._config.base_url + path
+        data = json.dumps(payload).encode("utf-8")
+        req = urllib.request.Request(url, data=data, headers=self._headers(), method="POST")
+        return self._send(req)
+
+    def _put(self, path: str, payload: dict[str, Any]) -> dict[str, Any] | None:
+        url = self._config.base_url + path
+        data = json.dumps(payload).encode("utf-8")
+        req = urllib.request.Request(url, data=data, headers=self._headers(), method="PUT")
+        return self._send(req)
+
+    def _send(self, req: urllib.request.Request) -> dict[str, Any] | None:
+        try:
+            with urllib.request.urlopen(req) as resp:
+                body = resp.read().decode("utf-8")
+                return json.loads(body) if body else {}
+        except urllib.error.HTTPError as e:
+            # Log but don't crash — caller decides how to handle None
+            status = e.code
+            body = ""
+            try:
+                body = e.read().decode("utf-8", errors="replace")[:500]
+            except Exception:
+                pass
+            print(f"  Discourse API error: {req.method} {req.full_url} -> {status}: {body}")
+            return None
+        except urllib.error.URLError as e:
+            print(f"  Discourse connection error: {req.full_url} -> {e.reason}")
+            return None
diff --git a/docs_sp/tools/nav_parser.py b/docs_sp/tools/nav_parser.py
new file mode 100644
index 0000000000..5a299f9513
--- /dev/null
+++ b/docs_sp/tools/nav_parser.py
@@ -0,0 +1,88 @@
+"""Parse zensical.toml nav structure into a flat list of doc entries.
+
+Reads the nav tree from zensical.toml and produces a flat list of
+{title, path, breadcrumb} dicts suitable for the sync orchestrator.
+"""
+
+from __future__ import annotations
+
+import tomllib
+from dataclasses import dataclass, field
+from pathlib import Path
+
+SKIP_FILES = frozenset({"index.md", "README.md"})
+
+
+@dataclass(frozen=True)
+class NavEntry:
+    """A single navigable documentation page."""
+
+    title: str
+    path: str
+    breadcrumb: tuple[str, ...] = field(default_factory=tuple)
+
+
+def parse(config_path: str | Path) -> list[NavEntry]:
+    """Parse zensical.toml and return all nav entries.
+
+    Args:
+        config_path: Path to zensical.toml.
+
+    Returns:
+        Flat list of NavEntry for every page in the nav tree,
+        excluding index.md, README.md, and external links.
+    """
+    config_path = Path(config_path)
+    with config_path.open("rb") as f:
+        config = tomllib.load(f)
+
+    nav = config.get("project", {}).get("nav", [])
+    entries = _flatten_nav(nav)
+    return [e for e in entries if Path(e.path).name not in SKIP_FILES]
+
+
+def parse_all(config_path: str | Path) -> list[NavEntry]:
+    """Like parse(), but includes index.md and README.md entries."""
+    config_path = Path(config_path)
+    with config_path.open("rb") as f:
+        config = tomllib.load(f)
+
+    nav = config.get("project", {}).get("nav", [])
+    return _flatten_nav(nav)
+
+
+def _flatten_nav(
+    items: list[dict[str, str | list] | str],
+    breadcrumb: tuple[str, ...] = (),
+) -> list[NavEntry]:
+    """Recursively flatten the nav tree into NavEntry objects."""
+    result: list[NavEntry] = []
+
+    for item in items:
+        if isinstance(item, dict):
+            for title, value in item.items():
+                if isinstance(value, str):
+                    # Skip external links
+                    if value.startswith("http"):
+                        continue
+                    result.append(NavEntry(
+                        title=title,
+                        path=value,
+                        breadcrumb=breadcrumb + (title,),
+                    ))
+                elif isinstance(value, list):
+                    result.extend(
+                        _flatten_nav(value, breadcrumb + (title,))
+                    )
+        elif isinstance(item, str):
+            # Bare path without title
+            if item.startswith("http"):
+                continue
+            name = Path(item).stem.replace("-", " ").capitalize()
+            result.append(NavEntry(
+                title=name,
+                path=item,
+                breadcrumb=breadcrumb + (name,),
+            ))
+
+    return result
diff --git a/docs_sp/tools/test_content_cache.py b/docs_sp/tools/test_content_cache.py
new file mode 100644
index 0000000000..fac78b7cf1
--- /dev/null
+++ b/docs_sp/tools/test_content_cache.py
@@ -0,0 +1,183 @@
+#!/usr/bin/env python3
+"""Tests for the SHA-256 content cache.
+
+Run: python3 docs_sp/tools/test_content_cache.py
+"""
+
+import sys
+import tempfile
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent))
+
+from content_cache import ContentCache
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def make_cache(tmp: str) -> ContentCache:
+    return ContentCache(cache_dir=Path(tmp) / ".discourse_sync_cache")
+
+
+# ---------------------------------------------------------------------------
+# Tests
+# ---------------------------------------------------------------------------
+
+
+def test_compute_hash_deterministic():
+    """Same content always produces the same hash."""
+    h1 = ContentCache.compute_hash("hello world")
+    h2 = ContentCache.compute_hash("hello world")
+    assert h1 == h2
+    assert len(h1) == 64  # SHA-256 hex digest length
+    print("  PASS: compute_hash_deterministic")
+
+
+def test_compute_hash_differs():
+    """Different content produces different hashes."""
+    h1 = ContentCache.compute_hash("hello world")
+    h2 = ContentCache.compute_hash("hello world!")
+    assert h1 != h2
+    print("  PASS: compute_hash_differs")
+
+
+def test_is_changed_no_cache():
+    """First run (no cache file) should report changed."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache = make_cache(tmp)
+        assert cache.is_changed("features/icbm.md", "content")
+    print("  PASS: is_changed_no_cache")
+
+
+def test_is_changed_after_save():
+    """After saving, same content should report unchanged."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache = make_cache(tmp)
+        cache.save("features/icbm.md", "content v1")
+        assert not cache.is_changed("features/icbm.md", "content v1")
+    print("  PASS: is_changed_after_save")
+
+
+def test_is_changed_after_modification():
+    """After saving, different content should report changed."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache = make_cache(tmp)
+        cache.save("features/icbm.md", "content v1")
+        assert cache.is_changed("features/icbm.md", "content v2")
+    print("  PASS: is_changed_after_modification")
+
+
+def test_separate_paths_independent():
+    """Different doc paths have independent caches."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache = make_cache(tmp)
+        cache.save("features/icbm.md", "content A")
+        cache.save("safety/safety.md", "content B")
+
+        assert not cache.is_changed("features/icbm.md", "content A")
+        assert not cache.is_changed("safety/safety.md", "content B")
+        assert cache.is_changed("features/icbm.md", "content B")
+        assert cache.is_changed("safety/safety.md", "content A")
+    print("  PASS: separate_paths_independent")
+
+
+def test_cache_dir_created_on_save():
+    """Cache directory is created automatically on first save."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache_dir = Path(tmp) / "nested" / "cache"
+        cache = ContentCache(cache_dir=cache_dir)
+        assert not cache_dir.exists()
+
+        cache.save("test.md", "content")
+        assert cache_dir.exists()
+        assert (cache_dir / "test.sha256").exists()
+    print("  PASS: cache_dir_created_on_save")
+
+
+def test_cache_file_naming():
+    """Cache files use slug derived from doc path."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache = make_cache(tmp)
+        cache.save("settings/cruise/speed-limit/source.md", "content")
+
+        expected_name = "settings_cruise_speed-limit_source.sha256"
+        cached_files = list(cache.cache_dir.glob("*.sha256"))
+        assert len(cached_files) == 1
+        assert cached_files[0].name == expected_name
+    print("  PASS: cache_file_naming")
+
+
+def test_clear_removes_all():
+    """clear() removes all .sha256 files and returns count."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache = make_cache(tmp)
+        cache.save("a.md", "aaa")
+        cache.save("b.md", "bbb")
+        cache.save("c.md", "ccc")
+
+        removed = cache.clear()
+        assert removed == 3
+        assert list(cache.cache_dir.glob("*.sha256")) == []
+    print("  PASS: clear_removes_all")
+
+
+def test_clear_empty_cache():
+    """clear() on nonexistent cache dir returns 0."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache = make_cache(tmp)
+        assert cache.clear() == 0
+    print("  PASS: clear_empty_cache")
+
+
+def test_overwrite_on_resave():
+    """Saving again overwrites the previous hash."""
+    with tempfile.TemporaryDirectory() as tmp:
+        cache = make_cache(tmp)
+        cache.save("doc.md", "version 1")
+        assert not cache.is_changed("doc.md", "version 1")
+        assert cache.is_changed("doc.md", "version 2")
+
+        cache.save("doc.md", "version 2")
+        assert cache.is_changed("doc.md", "version 1")
+        assert not cache.is_changed("doc.md", "version 2")
+    print("  PASS: overwrite_on_resave")
+
+
+# ---------------------------------------------------------------------------
+# Runner
+# ---------------------------------------------------------------------------
+
+
+if __name__ == "__main__":
+    print("Testing content cache:")
+    tests = [
+        test_compute_hash_deterministic,
+        test_compute_hash_differs,
+        test_is_changed_no_cache,
+        test_is_changed_after_save,
+        test_is_changed_after_modification,
+        test_separate_paths_independent,
+        test_cache_dir_created_on_save,
+        test_cache_file_naming,
+        test_clear_removes_all,
+        test_clear_empty_cache,
+        test_overwrite_on_resave,
+    ]
+    passed = 0
+    failed = 0
+    for test in tests:
+        try:
+            test()
+            passed += 1
+        except AssertionError as e:
+            print(f"  FAIL: {test.__name__}: {e}")
+            failed += 1
+        except Exception as e:
+            print(f"  ERROR: {test.__name__}: {e}")
+            failed += 1
+
+    print(f"\n{passed}/{passed + failed} tests passed")
+    sys.exit(1 if failed > 0 else 0)
diff --git a/docs_sp/tools/test_converter.py b/docs_sp/tools/test_converter.py
index f9befb8fbe..cca8b1679e 100644
--- a/docs_sp/tools/test_converter.py
+++ b/docs_sp/tools/test_converter.py
@@ -1,242 +1,209 @@
 #!/usr/bin/env python3
-"""Test the MkDocs → Discourse admonition conversion logic.
+"""Tests for the MkDocs -> Discourse markdown converter.
 
-This mirrors the Ruby converter's logic to verify correctness.
 Run: python3 docs_sp/tools/test_converter.py
 """
 
-import re
 import sys
+from pathlib import Path
 
-ADMONITION_MAP = {
-    "note": "NOTE",
-    "abstract": "ABSTRACT",
-    "info": "INFO",
-    "tip": "TIP",
-    "success": "SUCCESS",
-    "question": "QUESTION",
-    "warning": "WARNING",
-    "failure": "FAILURE",
-    "danger": "DANGER",
-    "bug": "BUG",
-    "example": "EXAMPLE",
-    "quote": "QUOTE",
-}
+# Ensure the tools directory is importable
+sys.path.insert(0, str(Path(__file__).parent))
+
+from converter import (
+    clean_blank_lines,
+    convert,
+    convert_admonitions,
+    convert_emoji_shortcodes,
+    convert_grid_cards,
+    convert_tabs,
+    resolve_internal_links,
+    strip_front_matter,
+)
+
+# ---------------------------------------------------------------------------
+# 1. Strip YAML Front Matter
+# ---------------------------------------------------------------------------
 
 
-def convert_admonitions(content: str) -> str:
-    """Convert MkDocs admonitions to Obsidian/Discourse callouts."""
-    lines = content.splitlines(keepends=True)
-    result = []
-    i = 0
+def test_strip_front_matter_basic():
+    input_text = """---
+title: My Page
+description: A test page
+---
 
-    pattern = re.compile(r'^(\s*)(!{3}|\?{3}\+?) (\w+)(?: "([^"]*)")?')
-
-    while i < len(lines):
-        line = lines[i]
-        m = pattern.match(line)
-
-        if m:
-            indent = m.group(1)
-            marker = m.group(2)
-            ad_type = m.group(3).lower()
-            title = m.group(4)
-
-            callout_type = ADMONITION_MAP.get(ad_type, ad_type.upper())
-
-            header = f"{indent}> [!{callout_type}]"
-            if title:
-                header += f" {title}"
-
-            if marker.startswith("???"):
-                collapsed = "+" not in marker
-                if not title:
-                    header += f" *(click to {'expand' if collapsed else 'collapse'})*"
-
-            result.append(header + "\n")
-            i += 1
-
-            content_indent = indent + "    "
-            while i < len(lines):
-                content_line = lines[i]
-                if content_line.startswith(content_indent):
-                    stripped = content_line[len(content_indent):]
-                    result.append(f"{indent}> {stripped}")
-                    i += 1
-                elif content_line.strip() == "":
-                    # Blank line: only treat as part of admonition if the
-                    # next non-blank line is still indented at content level
-                    j = i + 1
-                    while j < len(lines) and lines[j].strip() == "":
-                        j += 1
-                    if j < len(lines) and lines[j].startswith(content_indent):
-                        result.append(f"{indent}>\n")
-                        i += 1
-                    else:
-                        # Blank line ends the admonition
-                        break
-                else:
-                    break
-        else:
-            result.append(line)
-            i += 1
-
-    return "".join(result)
+# Hello
+"""
+    expected = """# Hello
+"""
+    result = strip_front_matter(input_text)
+    assert result == expected, f"FAIL:\n{result!r}\n!=\n{expected!r}"
+    print("  PASS: strip_front_matter_basic")
 
 
-# ---- Tests ----
+def test_strip_front_matter_absent():
+    input_text = "# Hello\n\nContent here.\n"
+    result = strip_front_matter(input_text)
+    assert result == input_text, f"FAIL:\n{result!r}\n!=\n{input_text!r}"
+    print("  PASS: strip_front_matter_absent")
+
+
+# ---------------------------------------------------------------------------
+# 2. Convert Admonitions
+# ---------------------------------------------------------------------------
+
 
 def test_basic_warning():
-    input_text = '''!!! warning "Important"
+    input_text = """!!! warning "Important"
     sunnypilot is a **driver assistance** system.
     Always pay attention.
-'''
-    expected = '''> [!WARNING] Important
+"""
+    expected = """> [!WARNING] Important
 > sunnypilot is a **driver assistance** system.
 > Always pay attention.
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL basic_warning:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: basic_warning")
 
 
 def test_info_no_title():
-    input_text = '''!!! info
+    input_text = """!!! info
     Content line 1
     Content line 2
-'''
-    expected = '''> [!INFO]
+"""
+    expected = """> [!INFO]
 > Content line 1
 > Content line 2
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL info_no_title:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: info_no_title")
 
 
 def test_info_with_title():
-    input_text = '''!!! info "Requirements"
+    input_text = """!!! info "Requirements"
     - Longitudinal control must be available
     - ICBM must be enabled
-'''
-    expected = '''> [!INFO] Requirements
+"""
+    expected = """> [!INFO] Requirements
 > - Longitudinal control must be available
 > - ICBM must be enabled
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL info_with_title:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: info_with_title")
 
 
 def test_danger():
-    input_text = '''!!! danger "Important"
+    input_text = """!!! danger "Important"
     sunnypilot is a **driver assistance** system. It is **NOT** a self-driving system.
-'''
-    expected = '''> [!DANGER] Important
+"""
+    expected = """> [!DANGER] Important
 > sunnypilot is a **driver assistance** system. It is **NOT** a self-driving system.
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL danger:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: danger")
 
 
 def test_tip():
-    input_text = '''!!! tip
+    input_text = """!!! tip
     The more detail you provide, the faster we can diagnose and fix the issue.
-'''
-    expected = '''> [!TIP]
+"""
+    expected = """> [!TIP]
 > The more detail you provide, the faster we can diagnose and fix the issue.
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL tip:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: tip")
 
 
 def test_multiline_with_blank():
-    input_text = '''!!! warning
+    input_text = """!!! warning
     Line 1
 
     Line 2 after blank
-'''
-    expected = '''> [!WARNING]
+"""
+    expected = """> [!WARNING]
 > Line 1
 >
 > Line 2 after blank
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL multiline_with_blank:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: multiline_with_blank")
 
 
 def test_collapsible():
-    input_text = '''??? warning "Click to see"
+    input_text = """??? warning "Click to see"
     Hidden content
-'''
-    expected = '''> [!WARNING] Click to see
+"""
+    expected = """> [!WARNING] Click to see
 > Hidden content
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL collapsible:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: collapsible")
 
 
 def test_collapsible_open():
-    input_text = '''???+ info "Open by default"
+    input_text = """???+ info "Open by default"
     Visible content
-'''
-    expected = '''> [!INFO] Open by default
+"""
+    expected = """> [!INFO] Open by default
 > Visible content
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL collapsible_open:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: collapsible_open")
 
 
 def test_surrounded_by_content():
-    input_text = '''Some text before.
+    input_text = """Some text before.
 
 !!! note "Note Title"
     Note content here.
 
 Some text after.
-'''
-    expected = '''Some text before.
+"""
+    expected = """Some text before.
 
 > [!NOTE] Note Title
 > Note content here.
 
 Some text after.
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL surrounded:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: surrounded_by_content")
 
 
 def test_multiple_admonitions():
-    input_text = '''!!! info "Requirements"
+    input_text = """!!! info "Requirements"
     - Req 1
     - Req 2
 
 !!! warning "Vehicle Restrictions"
     - Tesla: disabled on release
     - Rivian: always disabled
-'''
-    expected = '''> [!INFO] Requirements
+"""
+    expected = """> [!INFO] Requirements
 > - Req 1
 > - Req 2
 
 > [!WARNING] Vehicle Restrictions
 > - Tesla: disabled on release
 > - Rivian: always disabled
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL multiple:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: multiple_admonitions")
 
 
 def test_real_doc_snippet():
-    """Test with an actual snippet from docs_sp/settings/speed-limit.md."""
-    input_text = '''## Speed Limit Mode
+    """Test with an actual snippet from docs_sp content."""
+    input_text = """## Speed Limit Mode
 
 | Property | Value |
 |----------|-------|
@@ -251,8 +218,8 @@ def test_real_doc_snippet():
     - **Rivian:** Speed Limit Assist mode is always disabled
 
 ---
-'''
-    expected = '''## Speed Limit Mode
+"""
+    expected = """## Speed Limit Mode
 
 | Property | Value |
 |----------|-------|
@@ -267,15 +234,225 @@ def test_real_doc_snippet():
 > - **Rivian:** Speed Limit Assist mode is always disabled
 
 ---
-'''
+"""
     result = convert_admonitions(input_text)
     assert result == expected, f"FAIL real_doc:\n{result!r}\n!=\n{expected!r}"
     print("  PASS: real_doc_snippet")
 
 
+# ---------------------------------------------------------------------------
+# 3. Convert Tabs
+# ---------------------------------------------------------------------------
+
+
+def test_tabs_basic():
+    input_text = """=== "Tab One"
+    Content for tab one.
+
+=== "Tab Two"
+    Content for tab two.
+"""
+    expected = """**Tab One**
+
+Content for tab one.
+
+---
+
+**Tab Two**
+
+Content for tab two.
+
+---
+
+"""
+    result = convert_tabs(input_text)
+    assert result == expected, f"FAIL tabs_basic:\n{result!r}\n!=\n{expected!r}"
+    print("  PASS: tabs_basic")
+
+
+def test_tabs_multiline():
+    input_text = """=== "Details"
+    Line 1
+    Line 2
+    Line 3
+"""
+    expected = """**Details**
+
+Line 1
+Line 2
+Line 3
+
+---
+
+"""
+    result = convert_tabs(input_text)
+    assert result == expected, f"FAIL tabs_multiline:\n{result!r}\n!=\n{expected!r}"
+    print("  PASS: tabs_multiline")
+
+
+# ---------------------------------------------------------------------------
+# 4. Convert Grid Cards
+# ---------------------------------------------------------------------------
+
+
+def test_grid_cards_stripped():
+    input_text = """<div class="grid cards" markdown>
+
+- **Card 1** - Description
+- **Card 2** - Description
+
+</div>
+"""
+    expected = """
+
+- **Card 1** - Description
+- **Card 2** - Description
+
+"""
+    result = convert_grid_cards(input_text)
+    # Normalize whitespace for comparison
+    assert result.strip() == expected.strip(), f"FAIL grid_cards:\n{result!r}\n!=\n{expected!r}"
+    print("  PASS: grid_cards_stripped")
+
+
+# ---------------------------------------------------------------------------
+# 5. Convert Emoji Shortcodes
+# ---------------------------------------------------------------------------
+
+
+def test_emoji_known():
+    input_text = ":material-check: Supported | :material-close: Not supported"
+    expected = "Y Supported | N Not supported"
+    result = convert_emoji_shortcodes(input_text)
+    assert result == expected, f"FAIL emoji_known:\n{result!r}\n!=\n{expected!r}"
+    print("  PASS: emoji_known")
+
+
+def test_emoji_unknown_stripped():
+    input_text = ":material-unknown-icon: Some text"
+    expected = " Some text"
+    result = convert_emoji_shortcodes(input_text)
+    assert result == expected, f"FAIL emoji_unknown:\n{result!r}\n!=\n{expected!r}"
+    print("  PASS: emoji_unknown_stripped")
+
+
+def test_emoji_in_grid_card():
+    input_text = "- :material-rocket-launch: **[Feature](link.md)**"
+    expected = "-  **[Feature](link.md)**"
+    result = convert_emoji_shortcodes(input_text)
+    assert result == expected, f"FAIL emoji_grid:\n{result!r}\n!=\n{expected!r}"
+    print("  PASS: emoji_in_grid_card")
+
+
+# ---------------------------------------------------------------------------
+# 6. Resolve Internal Links
+# ---------------------------------------------------------------------------
+
+
+def test_internal_link_relative():
+    input_text = "See [ICBM](../features/cruise/icbm.md) for details."
+    result = resolve_internal_links(
+        input_text,
+        file_path="docs_sp/settings/cruise/speed-limit.md",
+        docs_base_url="https://docs.sunnypilot.ai",
+    )
+    assert "https://docs.sunnypilot.ai/" in result, f"FAIL internal_link:\n{result!r}"
+    assert ".md" not in result.split("](")[1], f"FAIL internal_link still has .md:\n{result!r}"
+    print("  PASS: internal_link_relative")
+
+
+def test_internal_link_with_anchor():
+    input_text = "See [section](./safety.md#driver-responsibility)."
+    result = resolve_internal_links(
+        input_text,
+        file_path="docs_sp/safety/index.md",
+        docs_base_url="https://docs.sunnypilot.ai",
+    )
+    assert "#driver-responsibility" in result, f"FAIL anchor preserved:\n{result!r}"
+    assert ".md" not in result.split("](")[1].split("#")[0], f"FAIL link has .md:\n{result!r}"
+    print("  PASS: internal_link_with_anchor")
+
+
+def test_external_link_untouched():
+    input_text = "Visit [GitHub](https://github.com/sunnypilot/sunnypilot)."
+    result = resolve_internal_links(
+        input_text,
+        file_path="docs_sp/index.md",
+        docs_base_url="https://docs.sunnypilot.ai",
+    )
+    assert result == input_text, f"FAIL external_link:\n{result!r}"
+    print("  PASS: external_link_untouched")
+
+
+# ---------------------------------------------------------------------------
+# 7. Clean Blank Lines
+# ---------------------------------------------------------------------------
+
+
+def test_clean_blank_lines():
+    input_text = "Line 1\n\n\n\n\nLine 2\n"
+    expected = "Line 1\n\n\nLine 2\n"
+    result = clean_blank_lines(input_text)
+    assert result == expected, f"FAIL clean_blanks:\n{result!r}\n!=\n{expected!r}"
+    print("  PASS: clean_blank_lines")
+
+
+def test_clean_blank_lines_no_change():
+    input_text = "Line 1\n\nLine 2\n"
+    result = clean_blank_lines(input_text)
+    assert result == input_text, f"FAIL clean_blanks_noop:\n{result!r}"
+    print("  PASS: clean_blank_lines_no_change")
+
+
+# ---------------------------------------------------------------------------
+# Integration: full convert()
+# ---------------------------------------------------------------------------
+
+
+def test_full_convert():
+    input_text = """---
+title: Test Doc
+---
+
+# Test Document
+
+!!! warning "Important"
+    Pay attention to the road.
+
+See [safety info](../safety/safety.md) for more.
+
+:material-check: Feature supported
+"""
+    result = convert(
+        input_text,
+        file_path="docs_sp/features/index.md",
+        docs_base_url="https://docs.sunnypilot.ai",
+    )
+    # Front matter stripped
+    assert "---\ntitle:" not in result, f"FAIL front matter not stripped:\n{result!r}"
+    # Admonition converted
+    assert "> [!WARNING] Important" in result, f"FAIL admonition:\n{result!r}"
+    assert "> Pay attention to the road." in result, f"FAIL admonition content:\n{result!r}"
+    # Link resolved
+    assert ".md" not in result.split("](")[1].split(")")[0], f"FAIL link:\n{result!r}"
+    # Emoji converted
+    assert ":material-check:" not in result, f"FAIL emoji:\n{result!r}"
+    assert "Y Feature supported" in result, f"FAIL emoji replacement:\n{result!r}"
+    print("  PASS: full_convert")
+
+
+# ---------------------------------------------------------------------------
+# Runner
+# ---------------------------------------------------------------------------
+
+
 if __name__ == "__main__":
-    print("Testing MkDocs → Discourse admonition conversion:")
+    print("Testing MkDocs -> Discourse converter:")
     tests = [
+        # 1. Front matter
+        test_strip_front_matter_basic,
+        test_strip_front_matter_absent,
+        # 2. Admonitions
         test_basic_warning,
         test_info_no_title,
         test_info_with_title,
@@ -287,6 +464,24 @@ if __name__ == "__main__":
         test_surrounded_by_content,
         test_multiple_admonitions,
         test_real_doc_snippet,
+        # 3. Tabs
+        test_tabs_basic,
+        test_tabs_multiline,
+        # 4. Grid cards
+        test_grid_cards_stripped,
+        # 5. Emoji
+        test_emoji_known,
+        test_emoji_unknown_stripped,
+        test_emoji_in_grid_card,
+        # 6. Internal links
+        test_internal_link_relative,
+        test_internal_link_with_anchor,
+        test_external_link_untouched,
+        # 7. Blank lines
+        test_clean_blank_lines,
+        test_clean_blank_lines_no_change,
+        # Integration
+        test_full_convert,
     ]
     passed = 0
     failed = 0
@@ -298,7 +493,7 @@ if __name__ == "__main__":
             print(f"  FAIL: {test.__name__}: {e}")
             failed += 1
         except Exception as e:
-            print(f"  FAIL: {test.__name__}: {e}")
+            print(f"  ERROR: {test.__name__}: {e}")
             failed += 1
 
     print(f"\n{passed}/{passed + failed} tests passed")
diff --git a/docs_sp/tools/test_discourse_client.py b/docs_sp/tools/test_discourse_client.py
new file mode 100644
index 0000000000..6f1fae8e7b
--- /dev/null
+++ b/docs_sp/tools/test_discourse_client.py
@@ -0,0 +1,438 @@
+#!/usr/bin/env python3
+"""Tests for the Discourse API client (fully mocked, no live requests).
+
+Run: python3 docs_sp/tools/test_discourse_client.py
+"""
+
+import io
+import json
+import sys
+import urllib.error
+import urllib.request
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+sys.path.insert(0, str(Path(__file__).parent))
+
+from discourse_client import DiscourseClient, DiscourseConfig
+
+TEST_CONFIG = DiscourseConfig(
+    base_url="https://community.sunnypilot.ai",
+    api_key="test-api-key-123",
+    api_user="docs-bot",
+    category_slug="documentation",
+)
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def mock_response(data: dict, status: int = 200) -> MagicMock:
+    """Create a mock urllib response with JSON body."""
+    body = json.dumps(data).encode("utf-8")
+    resp = MagicMock()
+    resp.read.return_value = body
+    resp.status = status
+    resp.__enter__ = lambda s: s
+    resp.__exit__ = MagicMock(return_value=False)
+    return resp
+
+
+def mock_http_error(status: int, body: str = "") -> urllib.error.HTTPError:
+    """Create a mock HTTPError."""
+    return urllib.error.HTTPError(
+        url="https://community.sunnypilot.ai/test",
+        code=status,
+        msg=f"HTTP {status}",
+        hdrs={},  # type: ignore[arg-type]
+        fp=io.BytesIO(body.encode("utf-8")),
+    )
+
+
+# ---------------------------------------------------------------------------
+# DiscourseConfig tests
+# ---------------------------------------------------------------------------
+
+
+def test_config_from_env():
+    env = {
+        "DISCOURSE_URL": "https://forum.example.com/",
+        "DISCOURSE_API_KEY": "secret-key",
+        "DISCOURSE_API_USER": "bot",
+        "DISCOURSE_CATEGORY": "docs",
+    }
+    with patch.dict("os.environ", env, clear=False):
+        config = DiscourseConfig.from_env()
+
+    assert config.base_url == "https://forum.example.com"  # trailing slash stripped
+    assert config.api_key == "secret-key"
+    assert config.api_user == "bot"
+    assert config.category_slug == "docs"
+    print("  PASS: config_from_env")
+
+
+def test_config_from_env_defaults():
+    env = {
+        "DISCOURSE_URL": "https://forum.example.com",
+        "DISCOURSE_API_KEY": "key",
+    }
+    with patch.dict("os.environ", env, clear=False):
+        # Remove optional vars if present
+        with patch.dict("os.environ", {"DISCOURSE_API_USER": "", "DISCOURSE_CATEGORY": ""}, clear=False):
+            pass
+        config = DiscourseConfig.from_env()
+
+    assert config.api_user in ("system", os.environ.get("DISCOURSE_API_USER", "system"))
+    print("  PASS: config_from_env_defaults")
+
+
+def test_config_missing_url():
+    env = {"DISCOURSE_API_KEY": "key"}
+    with patch.dict("os.environ", env, clear=True):
+        try:
+            DiscourseConfig.from_env()
+            assert False, "Should have raised ValueError"
+        except ValueError as e:
+            assert "DISCOURSE_URL" in str(e)
+    print("  PASS: config_missing_url")
+
+
+def test_config_missing_api_key():
+    env = {"DISCOURSE_URL": "https://forum.example.com"}
+    with patch.dict("os.environ", env, clear=True):
+        try:
+            DiscourseConfig.from_env()
+            assert False, "Should have raised ValueError"
+        except ValueError as e:
+            assert "DISCOURSE_API_KEY" in str(e)
+    print("  PASS: config_missing_api_key")
+
+
+def test_config_immutable():
+    try:
+        TEST_CONFIG.base_url = "https://other.com"  # type: ignore[misc]
+        assert False, "Should have raised"
+    except AttributeError:
+        pass
+    print("  PASS: config_immutable")
+
+
+# ---------------------------------------------------------------------------
+# get_category_id
+# ---------------------------------------------------------------------------
+
+
+@patch("urllib.request.urlopen")
+def test_get_category_id_found(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({"category": {"id": 42, "slug": "documentation"}})
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.get_category_id("documentation")
+
+    assert result == 42
+    call_args = mock_urlopen.call_args[0][0]
+    assert "/c/documentation/show.json" in call_args.full_url
+    assert call_args.get_header("Api-key") == "test-api-key-123"
+    assert call_args.get_header("Api-username") == "docs-bot"
+    print("  PASS: get_category_id_found")
+
+
+@patch("urllib.request.urlopen")
+def test_get_category_id_not_found(mock_urlopen: MagicMock):
+    mock_urlopen.side_effect = mock_http_error(404, "Not Found")
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.get_category_id("nonexistent")
+    assert result is None
+    print("  PASS: get_category_id_not_found")
+
+
+@patch("urllib.request.urlopen")
+def test_get_category_id_uses_default_slug(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({"category": {"id": 7}})
+    client = DiscourseClient(TEST_CONFIG)
+
+    client.get_category_id()  # no arg — uses config.category_slug
+
+    call_args = mock_urlopen.call_args[0][0]
+    assert "/c/documentation/show.json" in call_args.full_url
+    print("  PASS: get_category_id_uses_default_slug")
+
+
+# ---------------------------------------------------------------------------
+# find_topic_by_sync_id
+# ---------------------------------------------------------------------------
+
+
+@patch("urllib.request.urlopen")
+def test_find_topic_found(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({
+        "topics": [{"id": 101, "title": "ICBM Docs"}],
+    })
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.find_topic_by_sync_id("features/cruise/icbm.md")
+
+    assert result is not None
+    assert result["id"] == 101
+    call_args = mock_urlopen.call_args[0][0]
+    assert "/search.json?" in call_args.full_url
+    assert "docs-sync-id" in call_args.full_url
+    print("  PASS: find_topic_found")
+
+
+@patch("urllib.request.urlopen")
+def test_find_topic_not_found(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({"topics": []})
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.find_topic_by_sync_id("nonexistent.md")
+    assert result is None
+    print("  PASS: find_topic_not_found")
+
+
+@patch("urllib.request.urlopen")
+def test_find_topic_api_error(mock_urlopen: MagicMock):
+    mock_urlopen.side_effect = mock_http_error(500, "Internal Server Error")
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.find_topic_by_sync_id("features/icbm.md")
+    assert result is None
+    print("  PASS: find_topic_api_error")
+
+
+# ---------------------------------------------------------------------------
+# create_topic
+# ---------------------------------------------------------------------------
+
+
+@patch("urllib.request.urlopen")
+def test_create_topic_success(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({
+        "id": 501,
+        "topic_id": 201,
+        "topic_slug": "icbm-sunnypilot-docs",
+    })
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.create_topic(
+        title="ICBM - sunnypilot Docs",
+        raw="# ICBM\n\nDoc content here.",
+        category_id=42,
+        tags=["docs", "auto-sync"],
+    )
+
+    assert result is not None
+    assert result["topic_id"] == 201
+
+    call_args = mock_urlopen.call_args[0][0]
+    assert call_args.method == "POST"
+    assert "/posts.json" in call_args.full_url
+
+    sent_payload = json.loads(call_args.data.decode("utf-8"))
+    assert sent_payload["title"] == "ICBM - sunnypilot Docs"
+    assert sent_payload["category"] == 42
+    assert sent_payload["tags"] == ["docs", "auto-sync"]
+    assert "ICBM" in sent_payload["raw"]
+    print("  PASS: create_topic_success")
+
+
+@patch("urllib.request.urlopen")
+def test_create_topic_no_tags(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({"id": 502, "topic_id": 202})
+    client = DiscourseClient(TEST_CONFIG)
+
+    client.create_topic(title="Test", raw="body", category_id=1)
+
+    sent_payload = json.loads(mock_urlopen.call_args[0][0].data.decode("utf-8"))
+    assert "tags" not in sent_payload
+    print("  PASS: create_topic_no_tags")
+
+
+@patch("urllib.request.urlopen")
+def test_create_topic_failure(mock_urlopen: MagicMock):
+    mock_urlopen.side_effect = mock_http_error(422, '{"errors":["Title too short"]}')
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.create_topic(title="X", raw="body", category_id=1)
+    assert result is None
+    print("  PASS: create_topic_failure")
+
+
+# ---------------------------------------------------------------------------
+# update_post
+# ---------------------------------------------------------------------------
+
+
+@patch("urllib.request.urlopen")
+def test_update_post_success(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({"post": {"id": 501, "version": 2}})
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.update_post(post_id=501, raw="Updated content")
+
+    assert result is not None
+    call_args = mock_urlopen.call_args[0][0]
+    assert call_args.method == "PUT"
+    assert "/posts/501.json" in call_args.full_url
+
+    sent_payload = json.loads(call_args.data.decode("utf-8"))
+    assert sent_payload["post"]["raw"] == "Updated content"
+    assert sent_payload["post"]["edit_reason"] == "Documentation sync"
+    print("  PASS: update_post_success")
+
+
+@patch("urllib.request.urlopen")
+def test_update_post_custom_reason(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({"post": {"id": 501}})
+    client = DiscourseClient(TEST_CONFIG)
+
+    client.update_post(post_id=501, raw="content", edit_reason="Manual fix")
+
+    sent_payload = json.loads(mock_urlopen.call_args[0][0].data.decode("utf-8"))
+    assert sent_payload["post"]["edit_reason"] == "Manual fix"
+    print("  PASS: update_post_custom_reason")
+
+
+@patch("urllib.request.urlopen")
+def test_update_post_not_found(mock_urlopen: MagicMock):
+    mock_urlopen.side_effect = mock_http_error(404)
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.update_post(post_id=99999, raw="content")
+    assert result is None
+    print("  PASS: update_post_not_found")
+
+
+# ---------------------------------------------------------------------------
+# first_post_id
+# ---------------------------------------------------------------------------
+
+
+@patch("urllib.request.urlopen")
+def test_first_post_id_found(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({
+        "post_stream": {
+            "posts": [
+                {"id": 501, "post_number": 1},
+                {"id": 502, "post_number": 2},
+            ],
+        },
+    })
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.first_post_id(topic_id=201)
+    assert result == 501
+    print("  PASS: first_post_id_found")
+
+
+@patch("urllib.request.urlopen")
+def test_first_post_id_empty_stream(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({"post_stream": {"posts": []}})
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.first_post_id(topic_id=201)
+    assert result is None
+    print("  PASS: first_post_id_empty_stream")
+
+
+@patch("urllib.request.urlopen")
+def test_first_post_id_topic_not_found(mock_urlopen: MagicMock):
+    mock_urlopen.side_effect = mock_http_error(404)
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.first_post_id(topic_id=99999)
+    assert result is None
+    print("  PASS: first_post_id_topic_not_found")
+
+
+# ---------------------------------------------------------------------------
+# Headers / auth
+# ---------------------------------------------------------------------------
+
+
+@patch("urllib.request.urlopen")
+def test_headers_set_correctly(mock_urlopen: MagicMock):
+    mock_urlopen.return_value = mock_response({"category": {"id": 1}})
+    client = DiscourseClient(TEST_CONFIG)
+
+    client.get_category_id()
+
+    req = mock_urlopen.call_args[0][0]
+    assert req.get_header("Api-key") == "test-api-key-123"
+    assert req.get_header("Api-username") == "docs-bot"
+    assert req.get_header("Content-type") == "application/json"
+    print("  PASS: headers_set_correctly")
+
+
+# ---------------------------------------------------------------------------
+# Connection error
+# ---------------------------------------------------------------------------
+
+
+@patch("urllib.request.urlopen")
+def test_connection_error_returns_none(mock_urlopen: MagicMock):
+    mock_urlopen.side_effect = urllib.error.URLError("Connection refused")
+    client = DiscourseClient(TEST_CONFIG)
+
+    result = client.get_category_id()
+    assert result is None
+    print("  PASS: connection_error_returns_none")
+
+
+# ---------------------------------------------------------------------------
+# Runner
+# ---------------------------------------------------------------------------
+
+import os  # noqa: E402 (needed for test_config_from_env_defaults)
+
+if __name__ == "__main__":
+    print("Testing Discourse API client:")
+    tests = [
+        # Config
+        test_config_from_env,
+        test_config_from_env_defaults,
+        test_config_missing_url,
+        test_config_missing_api_key,
+        test_config_immutable,
+        # get_category_id
+        test_get_category_id_found,
+        test_get_category_id_not_found,
+        test_get_category_id_uses_default_slug,
+        # find_topic_by_sync_id
+        test_find_topic_found,
+        test_find_topic_not_found,
+        test_find_topic_api_error,
+        # create_topic
+        test_create_topic_success,
+        test_create_topic_no_tags,
+        test_create_topic_failure,
+        # update_post
+        test_update_post_success,
+        test_update_post_custom_reason,
+        test_update_post_not_found,
+        # first_post_id
+        test_first_post_id_found,
+        test_first_post_id_empty_stream,
+        test_first_post_id_topic_not_found,
+        # Misc
+        test_headers_set_correctly,
+        test_connection_error_returns_none,
+    ]
+    passed = 0
+    failed = 0
+    for test in tests:
+        try:
+            test()
+            passed += 1
+        except AssertionError as e:
+            print(f"  FAIL: {test.__name__}: {e}")
+            failed += 1
+        except Exception as e:
+            print(f"  ERROR: {test.__name__}: {e}")
+            failed += 1
+
+    print(f"\n{passed}/{passed + failed} tests passed")
+    sys.exit(1 if failed > 0 else 0)
diff --git a/docs_sp/tools/test_nav_parser.py b/docs_sp/tools/test_nav_parser.py
new file mode 100644
index 0000000000..652f341cf3
--- /dev/null
+++ b/docs_sp/tools/test_nav_parser.py
@@ -0,0 +1,238 @@
+#!/usr/bin/env python3
+"""Tests for the zensical.toml nav parser.
+
+Run: python3 docs_sp/tools/test_nav_parser.py
+"""
+
+import sys
+import tempfile
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent))
+
+from nav_parser import NavEntry, parse, parse_all, _flatten_nav
+
+ZENSICAL_TOML = Path(__file__).resolve().parent.parent.parent / "zensical.toml"
+
+
+# ---------------------------------------------------------------------------
+# Unit tests: _flatten_nav
+# ---------------------------------------------------------------------------
+
+
+def test_flatten_simple_dict():
+    nav = [{"Page One": "page-one.md"}]
+    result = _flatten_nav(nav)
+    assert len(result) == 1
+    assert result[0] == NavEntry(title="Page One", path="page-one.md", breadcrumb=("Page One",))
+    print("  PASS: flatten_simple_dict")
+
+
+def test_flatten_nested():
+    nav = [
+        {"Section": [
+            {"Child A": "section/a.md"},
+            {"Child B": "section/b.md"},
+        ]},
+    ]
+    result = _flatten_nav(nav)
+    assert len(result) == 2
+    assert result[0].title == "Child A"
+    assert result[0].path == "section/a.md"
+    assert result[0].breadcrumb == ("Section", "Child A")
+    assert result[1].breadcrumb == ("Section", "Child B")
+    print("  PASS: flatten_nested")
+
+
+def test_flatten_deep_nesting():
+    nav = [
+        {"L1": [
+            {"L2": [
+                {"L3": "deep/page.md"},
+            ]},
+        ]},
+    ]
+    result = _flatten_nav(nav)
+    assert len(result) == 1
+    assert result[0].breadcrumb == ("L1", "L2", "L3")
+    assert result[0].path == "deep/page.md"
+    print("  PASS: flatten_deep_nesting")
+
+
+def test_flatten_skips_external_links():
+    nav = [
+        {"Docs": "docs.md"},
+        {"Forum": "https://community.sunnypilot.ai"},
+    ]
+    result = _flatten_nav(nav)
+    assert len(result) == 1
+    assert result[0].title == "Docs"
+    print("  PASS: flatten_skips_external_links")
+
+
+def test_flatten_bare_string():
+    nav = ["getting-started/index.md"]
+    result = _flatten_nav(nav)
+    assert len(result) == 1
+    assert result[0].title == "Index"
+    assert result[0].path == "getting-started/index.md"
+    print("  PASS: flatten_bare_string")
+
+
+def test_flatten_mixed():
+    nav = [
+        {"Home": "index.md"},
+        {"Features": [
+            "features/index.md",
+            {"ICBM": "features/cruise/icbm.md"},
+            {"Forum": "https://example.com"},
+        ]},
+    ]
+    result = _flatten_nav(nav)
+    assert len(result) == 3  # Home, features/index.md (bare), ICBM
+    titles = [e.title for e in result]
+    assert "Home" in titles
+    assert "ICBM" in titles
+    assert "Forum" not in titles
+    print("  PASS: flatten_mixed")
+
+
+# ---------------------------------------------------------------------------
+# Unit tests: parse (filters index.md/README.md)
+# ---------------------------------------------------------------------------
+
+
+def test_parse_filters_index():
+    """parse() should exclude index.md and README.md entries."""
+    toml_content = b"""
+[project]
+nav = [
+    {"Home" = "index.md"},
+    {"Guide" = [
+        "guide/index.md",
+        {"Setup" = "guide/setup.md"},
+    ]},
+]
+"""
+    with tempfile.NamedTemporaryFile(suffix=".toml", delete=False) as f:
+        f.write(toml_content)
+        f.flush()
+        result = parse(f.name)
+
+    assert len(result) == 1
+    assert result[0].title == "Setup"
+    assert result[0].path == "guide/setup.md"
+    print("  PASS: parse_filters_index")
+
+
+def test_parse_all_includes_index():
+    """parse_all() should include index.md entries."""
+    toml_content = b"""
+[project]
+nav = [
+    {"Home" = "index.md"},
+    {"Setup" = "guide/setup.md"},
+]
+"""
+    with tempfile.NamedTemporaryFile(suffix=".toml", delete=False) as f:
+        f.write(toml_content)
+        f.flush()
+        result = parse_all(f.name)
+
+    assert len(result) == 2
+    titles = [e.title for e in result]
+    assert "Home" in titles
+    assert "Setup" in titles
+    print("  PASS: parse_all_includes_index")
+
+
+# ---------------------------------------------------------------------------
+# Integration: parse real zensical.toml
+# ---------------------------------------------------------------------------
+
+
+def test_parse_real_zensical():
+    """Parse the actual zensical.toml and verify structure."""
+    if not ZENSICAL_TOML.exists():
+        print("  SKIP: parse_real_zensical (zensical.toml not found)")
+        return
+
+    all_entries = parse_all(ZENSICAL_TOML)
+    filtered_entries = parse(ZENSICAL_TOML)
+
+    # Sanity checks on totals
+    assert len(all_entries) > 50, f"Expected 50+ total entries, got {len(all_entries)}"
+    assert len(filtered_entries) > 40, f"Expected 40+ filtered entries, got {len(filtered_entries)}"
+    assert len(filtered_entries) < len(all_entries), "Filtering should remove some entries"
+
+    # Every filtered entry should NOT be index.md or README.md
+    for entry in filtered_entries:
+        assert Path(entry.path).name not in ("index.md", "README.md"), (
+            f"Filtered list contains {entry.path}"
+        )
+
+    # No external links should be present
+    for entry in all_entries:
+        assert not entry.path.startswith("http"), f"External link leaked: {entry.path}"
+
+    # Check some known entries exist
+    paths = {e.path for e in filtered_entries}
+    assert "getting-started/what-is-sunnypilot.md" in paths, "Missing what-is-sunnypilot"
+    assert "features/cruise/icbm.md" in paths, "Missing ICBM"
+    assert "safety/safety.md" in paths, "Missing safety"
+
+    # Check breadcrumbs are populated
+    icbm = next(e for e in filtered_entries if e.path == "features/cruise/icbm.md")
+    assert len(icbm.breadcrumb) >= 2, f"ICBM breadcrumb too short: {icbm.breadcrumb}"
+    assert "Features" in icbm.breadcrumb or "Cruise Control" in icbm.breadcrumb
+
+    print(f"  PASS: parse_real_zensical ({len(all_entries)} total, {len(filtered_entries)} filtered)")
+
+
+def test_nav_entry_immutable():
+    """NavEntry is frozen — attributes cannot be reassigned."""
+    entry = NavEntry(title="Test", path="test.md", breadcrumb=("Test",))
+    try:
+        entry.title = "Modified"  # type: ignore[misc]
+        assert False, "Should have raised FrozenInstanceError"
+    except AttributeError:
+        pass
+    print("  PASS: nav_entry_immutable")
+
+
+# ---------------------------------------------------------------------------
+# Runner
+# ---------------------------------------------------------------------------
+
+
+if __name__ == "__main__":
+    print("Testing nav parser:")
+    tests = [
+        # Unit
+        test_flatten_simple_dict,
+        test_flatten_nested,
+        test_flatten_deep_nesting,
+        test_flatten_skips_external_links,
+        test_flatten_bare_string,
+        test_flatten_mixed,
+        test_parse_filters_index,
+        test_parse_all_includes_index,
+        test_nav_entry_immutable,
+        # Integration
+        test_parse_real_zensical,
+    ]
+    passed = 0
+    failed = 0
+    for test in tests:
+        try:
+            test()
+            passed += 1
+        except AssertionError as e:
+            print(f"  FAIL: {test.__name__}: {e}")
+            failed += 1
+        except Exception as e:
+            print(f"  ERROR: {test.__name__}: {e}")
+            failed += 1
+
+    print(f"\n{passed}/{passed + failed} tests passed")
+    sys.exit(1 if failed > 0 else 0)