Plan 87: add GitHub Alerts detection and fix to MDS034

[jeduden]

Summary

Implements MDS034, a new linting rule that validates Markdown syntax against a declared target flavor (CommonMark, GFM, or Goldmark) and flags unsupported syntax features.

Key Changes

• Feature detection system (features.go): Defines 13 tracked Markdown features (tables, task lists, strikethrough, bare-URL autolinks, footnotes, definition lists, heading IDs, superscript, subscript, math blocks/inline, abbreviations, GitHub alerts) and maps their support across three flavors.

• Dual-parser AST detection (detect.go): Implements comprehensive feature detection using goldmark's built-in extensions for tables, strikethrough, task lists, footnotes, definition lists, and heading IDs. Includes specialized detectors for bare-URL autolinks (regex-based text scanning) and GitHub Alerts (blockquote pattern matching).

• Rule implementation (rule.go): Implements the MDS034 rule with:

  • Configuration support for flavor setting (commonmark, gfm, goldmark)
  • Check() method that reports diagnostics for unsupported features
  • Fix() method that removes GitHub Alert marker lines when the flavor doesn't support them
  • Opt-in by default (disabled unless explicitly configured)

• Parser caching (parser.go): Provides a singleton goldmark parser with extensions enabled for efficient AST-based detection across multiple files.

• Comprehensive test coverage:

  • Unit tests for feature detection, flavor parsing, and rule behavior
  • Integration tests for all three flavors with various feature combinations
  • Test fixtures demonstrating good/bad examples and fix behavior

• Documentation (README.md): Complete rule documentation with feature support matrix, configuration examples, and detected features breakdown.

Notable Implementation Details

• The detector uses a dual-parse strategy: CommonMark parse for bare URLs and GitHub Alerts, goldmark parse with extensions for other features, then merges results in document order.
• Bare-URL detection intelligently skips URLs inside links, autolinks, code spans, and code blocks to avoid false positives.
• GitHub Alerts detection is case-sensitive per GFM spec and matches the five standard tokens (NOTE, TIP, IMPORTANT, WARNING, CAUTION).
• Finding positions are body-relative (excluding front-matter) with precise byte anchors for features requiring exact spans.
• The goldmark profile is mdsmith-defined: accepts GFM features plus heading IDs, but rejects optional extensions (footnotes, definition lists, math, abbreviations).

https://claude.ai/code/session_018PqzkvcKjWCSc7k9NAh3wm

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.40%. Comparing base (22695b4) to head (62670fc).
⚠️ Report is 8 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #153      +/-   ##
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+ Coverage   87.32%   87.40%   +0.07%     
==========================================
  Files         107      107              
  Lines       13220    13300      +80     
==========================================
+ Hits        11545    11625      +80     
  Misses       1218     1218              
  Partials      457      457              

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[Copilot]

Pull request overview

Implements a new opt-in rule (MDS034) to validate Markdown syntax against a configured target flavor (commonmark, gfm, goldmark), including detection/fixing for GitHub Alerts, and wires the rule into the CLI + integration fixture runner.

Changes:

• Added internal/rules/markdownflavor package implementing MDS034 (feature registry, detectors, shared parser, rule + fixes) with unit tests.
• Added MDS034 rule documentation and fixtures (good/bad/fixed) and registered the rule in the CLI + rule index.
• Updated integration fixture harness to avoid MDS033’s process-level warning leaking across fixture runs.

Reviewed changes

Copilot reviewed 31 out of 31 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
plan/87_markdown-flavor-github-alerts.md	Marks GitHub Alerts flavor validation plan as completed with tasks checked off.
plan/86_markdown-flavor-validation.md	Updates plan 86 status and task breakdown to reflect partial completion.
internal/rules/markdownflavor/features.go	Defines flavors/features and flavor support table for MDS034.
internal/rules/markdownflavor/features_test.go	Tests for flavor parsing/stringification and support matrix expectations.
internal/rules/markdownflavor/parser.go	Adds cached goldmark parser with extensions enabled for AST-based detection.
internal/rules/markdownflavor/parser_test.go	Verifies cached parser instance and that key extension nodes appear in the AST.
internal/rules/markdownflavor/detect.go	Implements feature detection (dual parse + regex/pattern detectors) and finding ordering.
internal/rules/markdownflavor/detect_test.go	Unit tests for detectors, filtering behavior, and ordering.
internal/rules/markdownflavor/rule.go	Implements MDS034 rule Check/Fix and config handling; registers rule.
internal/rules/markdownflavor/rule_test.go	Unit tests for rule identity/config, diagnostics, flavor behavior, and Fix for alerts.
internal/rules/MDS034-markdown-flavor/README.md	Adds rule documentation, settings, feature matrix, and examples.
internal/rules/MDS034-markdown-flavor/good/commonmark.md	“Good” fixture for commonmark flavor.
internal/rules/MDS034-markdown-flavor/good/gfm.md	“Good” fixture for gfm flavor.
internal/rules/MDS034-markdown-flavor/good/goldmark.md	“Good” fixture for goldmark flavor.
internal/rules/MDS034-markdown-flavor/bad/commonmark-task-list.md	“Bad” fixture asserting task list diagnostics under commonmark.
internal/rules/MDS034-markdown-flavor/bad/commonmark-table.md	“Bad” fixture asserting table diagnostics under commonmark.
internal/rules/MDS034-markdown-flavor/bad/commonmark-strikethrough.md	“Bad” fixture asserting strikethrough diagnostics under commonmark.
internal/rules/MDS034-markdown-flavor/bad/commonmark-heading-id.md	“Bad” fixture asserting heading-ID diagnostics under commonmark.
internal/rules/MDS034-markdown-flavor/bad/commonmark-bare-url.md	“Bad” fixture asserting bare-URL diagnostics under commonmark.
internal/rules/MDS034-markdown-flavor/bad/commonmark-github-alerts.md	“Bad” fixture asserting GitHub Alerts diagnostics under commonmark.
internal/rules/MDS034-markdown-flavor/bad/gfm-heading-id.md	“Bad” fixture asserting heading-ID diagnostics under gfm.
internal/rules/MDS034-markdown-flavor/bad/gfm-footnote.md	“Bad” fixture asserting footnote diagnostics under gfm.
internal/rules/MDS034-markdown-flavor/bad/gfm-definition-list.md	“Bad” fixture asserting definition list diagnostics under gfm.
internal/rules/MDS034-markdown-flavor/bad/goldmark-github-alerts.md	“Bad” fixture asserting GitHub Alerts diagnostics under goldmark.
internal/rules/MDS034-markdown-flavor/fixed/commonmark-github-alerts.md	Expected fixed output after removing alert marker under commonmark.
internal/rules/MDS034-markdown-flavor/fixed/goldmark-github-alerts.md	Expected fixed output after removing alert marker under goldmark.
internal/rules/index.md	Adds MDS034 to the internal rule catalog.
internal/rules/directorystructure/rule.go	Adds test helper to silence the process-level config warning.
internal/integration/rules_test.go	Imports and uses the new silence helper; registers markdownflavor rule for fixtures.
cmd/mdsmith/main.go	Registers markdownflavor rule package in the CLI.
PLAN.md	Updates plan catalog statuses for plan 86/87.

[Copilot]

Pull request overview

Copilot reviewed 31 out of 31 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 31 out of 31 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 14 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 14 changed files in this pull request and generated no new comments.

[jeduden]

🟢 Merge Queue — picked up

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[jeduden]

🔵 Merge Queue — CI running

Merged into batch branch merge-queue/batch-153-1776847088. View CI run.

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[jeduden]

✅ Merge Queue — merged

This PR landed on main via commit afe06e6. CI run that validated the merge.

Next: Done — nothing more to do here.