t.1fn: safe and extensible ace-lint fix system

[cs3b]

📋 Summary

ace-lint --fix now applies surgical, line-level edits instead of reformatting entire files through kramdown — preserving frontmatter, code blocks, and document structure. A new --auto-fix-with-agent flag provides LLM-assisted repair for issues that deterministic rules cannot fix, and --dry-run lets you preview fixes without writing.

Previously, --fix used kramdown round-trip formatting which could silently rewrite frontmatter, collapse tables, and alter HTML attributes.

✏️ Changes

• Add MarkdownSurgicalFixer: line-level fix molecule for em-dash, smart quotes, trailing whitespace, blank-line rules, and trailing newline — skips fenced code blocks and frontmatter (c5f800131)
• Add guarded kramdown formatting: structural-risk checks (frontmatter, fence count, table rows, HTML attributes) before write in KramdownFormatter (c5f800131)
• Add --auto-fix (aliases --fix, -f): deterministic surgical fix → re-lint pipeline (5dd5af7ec)
• Add --auto-fix-with-agent: LLM-assisted repair using Ace::LLM::QueryInterface with prompt construction (5dd5af7ec)
• Add --dry-run (-n): preview fixes without writing (5dd5af7ec)
• Add --model: override LLM model for agent-assisted fixes (5dd5af7ec)
• Fix auto-fix exit code: return exit 1 when violations remain after fix (9bba87e28)
• Add lint.doctor_agent_model config key in .ace-defaults/lint/config.yml (5dd5af7ec)
• Update LintOrchestrator: --fix runs surgical fixer, --format runs guarded kramdown, --fix --format runs both in correct order (c5f800131)

📁 File Changes

+1272,  -109   24 files   total

+1105,   -53   18 files      ace-lint/
 +679,   -38    7 files   🧱 lib/
   +1,    -0                 ace/lint.rb
 +230,    -7                 ace/lint/cli/commands/lint.rb
  +68,    -9                 ace/lint/molecules/kramdown_formatter.rb
  +67,   -18                 .../markdown_linter.rb
 +277,    -0                 .../markdown_surgical_fixer.rb
  +35,    -3                 ace/lint/organisms/lint_orchestrator.rb
   +1,    -1                 ace/lint/version.rb
 +352,    -3    6 files   🧪 test/
 +111,    -0                 commands/lint_command_test.rb
   +3,    -3                 e2e/TS-LINT-001-lint-pipeline/TC-003-fix-mode.runner.md
  +79,    -0                 molecules/kramdown_formatter_test.rb
  +22,    -0                 .../markdown_linter_test.rb
  +93,    -0                 .../markdown_surgical_fixer_test.rb
  +44,    -0                 organisms/lint_orchestrator_test.rb
  +74,   -12    5 files      
   +3,    -2                 .ace-defaults/lint/config.yml
  +36,    -0                 CHANGELOG.md
   +3,    -1                 README.md
  +15,    -4                 docs/getting-started.md
  +17,    -5                 .../usage.md

  +32,    -1    2 files      ./
  +29,    -0                 CHANGELOG.md
   +3,    -1                 docs/tools.md

🧪 Test Evidence

• MarkdownSurgicalFixerTest (10 tests) — validates line-level surgical edits: em-dash, smart quotes, trailing whitespace, blank-line rules, frontmatter/code-block preservation, missing file error handling
• KramdownFormatterTest (8 tests) — validates guarded formatting with structural-risk detection
• MarkdownLinterTest (expanded) — validates fenced-code-state tracking and trailing whitespace warning detection
• LintOrchestratorTest (expanded) — validates fix/format pipeline ordering and mode combinations
• LintCommandTest (11 tests) — validates CLI flag parsing, auto-fix flow, agent-assisted path, dry-run, format warning
• Suite totals: 294 tests, 874 assertions, 0 failures, 0 errors
• Full monorepo: 7493/7494 tests pass (1 pre-existing ace-docs failure)
• E2E: TS-LINT-001 passes 7/7 after fixture refresh

📦 Releases

• ace-lint v0.26.0 — Add surgical markdown fixes and guarded kramdown formatting
• ace-lint v0.27.0 — Add deterministic auto-fix (--auto-fix) and agent-assisted repair (--auto-fix-with-agent) flags

🎮 Demo

Surgical fix (deterministic)

ace-lint --auto-fix README.md

Dry-run preview

ace-lint --auto-fix --dry-run README.md

Agent-assisted fix

ace-lint --auto-fix-with-agent --model anthropic:sonnet README.md