fix-unclosed-fenced-block-en

name	fix-unclosed-fenced-block-en
version	1.0.0
description	Detect and fix unclosed fenced blocks (``` ... ```) in Markdown text. Use this skill whenever the user reports that a fenced block was not closed, when generated Markdown contains an unclosed fence, or when a heading or new section appears inside what should have been a fenced block. Fenced blocks are used for code, terminal output, file trees, config files, examples, and any verbatim content. Triggers on phrases like "unclosed fenced block", "missing closing fence", "backtick block not closed", or when the user pastes broken Markdown output for repair. Apply proactively when reviewing any self-generated Markdown before delivering it to the user.
license	CC BY-NC-SA 4.0
language	en
author	roebi (Robert Halter)
attribution	Part of the roebi agent-skills library. https://github.com/roebi/agent-skills
spec	https://agentskills.io/specification

fix-unclosed-fenced-block-en

Detect and fix unclosed fenced blocks (```) in Markdown output. Fenced blocks are used for code, terminal output, file trees, config files, examples, and any verbatim content.

---

Problem description

When an AI assistant generates Markdown, it sometimes opens a fenced code block with ``` (optionally followed by a language hint such as bash or markdown) but then omits the matching closing ```.
The symptom is that the next heading or section renders inside the code block instead of as normal Markdown.

Typical broken pattern:

Some prose text.

```bash
skills-ref validate ./skills/my-skill

## Next heading        <-- should be outside the code block, but is not

---

Detection algorithm

Scan the Markdown text line by line and maintain a simple toggle:

State	Trigger	Action
OUTSIDE	Line matches /^```/	Switch to INSIDE, record line number and language hint
INSIDE	Line matches /^```\s*$/ (closing fence)	Switch to OUTSIDE
INSIDE	Line matches ^#{1,6} (ATX heading)	Missing close detected — insert ``` before the heading
INSIDE	End of document reached	Missing close detected — append ``` at end

A closing fence must be exactly three or more backticks on their own line (optional trailing whitespace). A line that starts with ``` but has additional non-whitespace characters is an opening fence.

---

Fix procedure

Step 1 — Identify all unclosed blocks

Apply the detection algorithm above to the full input text and collect every location where a closing fence is missing.

Step 2 — Insert closing fences

For each missing close (in reverse order so line numbers stay valid):

1. Insert a line containing exactly ``` immediately before the triggering heading (or at the end of the document).
2. Add a blank line after the inserted fence if one is not already present, to preserve heading spacing.

Step 3 — Verify the result

Re-run the detection algorithm on the repaired text and confirm that no unclosed blocks remain.

Step 4 — Report

Tell the user:

• How many unclosed blocks were found and fixed.
• The approximate location of each fix (heading text or "end of document").

---

Self-check before output

Before delivering any Markdown response, mentally (or literally) run the detection algorithm on your own output. If an unclosed block is found, apply the fix before sending.

Checklist:

• Every ``` opener has a matching ``` closer on its own line.
• No ATX heading (# … ######) appears between an opener and its closer.
• The document does not end while inside a fenced block.

---

Examples

Example 1 — heading triggers missing close

Input (broken):

Preserve language hints:
```bash
skills-ref validate ./skills/my-skill

## Citations

Fixed output:

Preserve language hints:
```bash
skills-ref validate ./skills/my-skill

Citations

---

### Example 2 — end of document triggers missing close

**Input (broken):**

```markdown
Keep inline citation format:

```markdown
According to the agentskills.io specification, the `name` field must match
the directory name exactly.

Fixed output:

Keep inline citation format:

```markdown
According to the agentskills.io specification, the `name` field must match
the directory name exactly.

---

## Edge cases

| Situation | Handling |
|-----------|----------|
| Nested backtick fences (four backticks) | Track fence depth; a four-backtick opener closes with four backticks |
| Inline backticks (single or double) | Ignored — only triple-backtick fences are relevant |
| Indented code blocks (4 spaces) | Not affected by this skill |
| Fence with language hint | Opening fence; closing fence has no hint |
| Multiple consecutive unclosed blocks | Fix each one individually in document order |

---

## Attribution

fix-unclosed-fenced-block-en — part of the roebi agent-skills library Author : roebi (Robert Halter), Switzerland License: CC BY-NC-SA 4.0 https://creativecommons.org/licenses/by-nc-sa/4.0/ Spec : https://agentskills.io/specification Source : https://github.com/roebi/agent-skills