feat(seo): config-driven llms.txt generator in seo-static plugin

[PierreBrisorgueil]

Closes #4269

What

Adds a generic, config-driven buildLlmsTxt(llmsConfig, app) builder to src/lib/plugins/seo-static.js, mirroring buildRobotsTxt / buildSitemapXml / buildManifestJson, and emits llms.txt from the generateBundle hook (prod build only, gated on config).

Why

llms.txt is the emerging LLM/answer-engine site entry point (AEO). Keeping it in the stack plugin lets every downstream project ship its own llms.txt from config, consistent with how robots/sitemap/manifest are already generated — instead of a hand-maintained public/llms.txt.

Rendering

# title (fallback app.title → 'App'), > summary, intro, per-section ## title with items as - [label](url): note (link) or - label: note (bullet), then body passthrough; single trailing newline. Sections without a title and items without a label are skipped (no undefined in output); app is null-guarded.

Tests

src/lib/plugins/tests/seo-static.unit.tests.js — describe('buildLlmsTxt'): disabled→null, undefined→null, title fallback, summary/intro, link-vs-bullet + note, body passthrough + trailing newline, app=undefined fallback, malformed-entry skipping, testConfig fixture render. Plugin emit-count test updated 3→4. Generic — zero project-specific strings.

Scope

• Stack (devkit Vue) only. Generic generator + unit test + test fixture.
• Out of scope (downstream): the Trawl seo.llms content + /update-stack propagation land on GTM driver C1-1 (board comes-io/projects/3) in comes-io/trawl_vue.

---

🤖 First run of the "GTM Engineer generates the issue → the dev flow dépiles it" pattern. Driver: comes-io/projects/3 item C1-1. Plan: infra/docs/superpowers/plans/2026-06-08-trawl-llms-txt.md. Draft — human merge gate (do not self-merge).

Summary by CodeRabbit

• New Features

  • Added automatic generation of llms.txt file during production builds with configurable options
  • Support for customizing content structure including summary, introduction, sections, and body
  • Ability to enable/disable LLM content generation via configuration settings

• Tests

  • Added comprehensive test coverage for the new file generation functionality

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 2e5bad4 and 19ef70b.

📒 Files selected for processing (3)

• src/config/defaults/test.config.js
• src/lib/plugins/seo-static.js
• src/lib/plugins/tests/seo-static.unit.tests.js

---

Walkthrough

This PR introduces config-driven llms.txt generation to the SEO static plugin. A new buildLlmsTxt builder generates LLM-friendly Markdown with title, summary, intro, sections with optional links, and body content. The plugin's generateBundle hook emits llms.txt when enabled, following the existing pattern for robots.txt, sitemap.xml, and manifest.json.

Changes

LLMs.txt Generation Feature

Layer / File(s)	Summary
LLMs.txt builder function src/lib/plugins/seo-static.js	Exports buildLlmsTxt(llmsConfig, app) that returns null when disabled, or a Markdown string with title, summary, intro, sections with items (rendered as links or bullets with notes), and body. JSDoc updated to document llms.txt as an emitted asset.
Plugin hook integration src/lib/plugins/seo-static.js	Extends generateBundle to call buildLlmsTxt and conditionally emit llms.txt asset when the builder returns non-null content.
Test configuration and unit tests src/config/defaults/test.config.js, src/lib/plugins/tests/seo-static.unit.tests.js	Test fixture defines example llms config structure. Updated imports and generateBundle test to expect four emitted assets. New buildLlmsTxt test suite validates null behavior when disabled, markdown structure, link/bullet formatting, notes, body passthrough, and fixture rendering.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• pierreb-devkit/Vue#3658: Extends the same seo-static.js plugin to add llms.txt generation alongside existing SEO asset emission.

Suggested labels

Feat

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: adding a config-driven llms.txt generator to the seo-static plugin.
Description check	✅ Passed	The description provides what changed, why it matters, rendering details, test coverage, and scope—all required template sections are addressed comprehensively.
Linked Issues check	✅ Passed	The PR implements all acceptance criteria from #4269: buildLlmsTxt returns null when disabled, renders markdown with proper structure, emits llms.txt from generateBundle, includes unit tests, and contains zero project-specific strings.
Out of Scope Changes check	✅ Passed	All changes are directly aligned with #4269 scope: the generic builder function, plugin integration, unit tests, and test fixture. Downstream GTM propagation is correctly marked as out-of-scope.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/4269-llms-txt-generator

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.58%. Comparing base (2e614db) to head (19ef70b).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #4274   +/-   ##
=======================================
  Coverage   99.57%   99.58%           
=======================================
  Files          31       31           
  Lines        1182     1200   +18     
  Branches      340      352   +12     
=======================================
+ Hits         1177     1195   +18     
  Misses          5        5           

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[Copilot]

Pull request overview

Adds first-class llms.txt generation to the existing seo-static Vite plugin, following the same config-driven pattern as robots.txt, sitemap.xml, and manifest.json, so downstream apps can ship llms.txt via config rather than a static public file.

Changes:

• Add buildLlmsTxt(llmsConfig, app) builder and emit llms.txt as a production-build asset when enabled.
• Add unit tests covering buildLlmsTxt rendering, null behavior, skipping malformed entries, and fixture rendering.
• Extend test.config.js fixture with a generic app.seo.llms example used by the tests.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/lib/plugins/seo-static.js	Implements buildLlmsTxt and emits llms.txt from generateBundle when enabled.
src/lib/plugins/tests/seo-static.unit.tests.js	Adds buildLlmsTxt unit tests and updates the plugin emit-count assertion from 3 → 4.
src/config/defaults/test.config.js	Adds a generic seo.llms fixture used by the new tests.