docs(claude-md): add LLM-facing files + RTD layout sections

Backport two sections from current CLAUDE.md missing from sagitta (#1907):
- LLM-Facing Files: llms.txt/llms-full.txt generation, template location.
- Read the Docs Layout: full RTD slug table and html_baseurl guidance.

🤖 Generated by [robots](https://vyos.io)

1 files changed, 44 insertions, 0 deletions

diff --git a/CLAUDE.md b/CLAUDE.md
index 99320758..ae0c16f5 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -187,6 +187,50 @@ Two valid uses:
 
 A PR that both adds and removes TODOs is not contradictory; intent matters.
 
+## LLM-Facing Files (`llms.txt`, `llms-full.txt`)
+
+Both files are regenerated on every `html` and `readthedocs` builder run.
+The `dirhtml` builder is intentionally skipped — production publishes
+only via `html`/`readthedocs`, and we don't render llms.txt for builds
+we don't ship. Local `make dirhtml` is a developer convenience and
+won't emit `llms.txt`.
+
+Files are shipped at the docs root for each version
+(`https://docs.vyos.io/en/<version>/llms.txt`, `.../llms-full.txt`).
+
+- **`llms-full.txt`** — auto-generated by the `sphinx_llms_txt` extension from
+  the full corpus. No curation; configured by `llms_txt_file = False` (which
+  disables the extension's *index* output, not the full output).
+- **`llms.txt`** — curated overview rendered at build time from
+  `docs/_templates/llms.txt.j2`. URLs and the version line are interpolated
+  from `html_baseurl` and `release` so the file always matches the branch.
+  The render lives in `_write_llms_txt(app, exception)` in `docs/conf.py`,
+  wired via `app.connect('build-finished', ...)`.
+
+When adding new top-level sections to the docs, add a corresponding bullet in
+`docs/_templates/llms.txt.j2`. Branch-specific differences (e.g. sagitta has
+no `vpp/` or `contributing/index`) live in that branch's copy of the template.
+
+## Read the Docs Layout
+
+RTD slugs as of 2026-05-04 (verified via API):
+
+| Slug | Verbose | Branch | Role |
+|---|---|---|---|
+| `rolling` | current | `current` | canonical for rolling/next major |
+| `1.5` | circinus | `circinus` | canonical for current LTS |
+| `1.4` | sagitta | `sagitta` | canonical for previous LTS |
+| `1.3`, `1.2` | equuleus, crux | older | canonical for older releases |
+
+URL-level redirect aliases (resolve to the canonicals above):
+`/en/latest/* → /en/rolling/`, `/en/lts/* → /en/1.5/`,
+`/en/stable/* → /en/lts/`, `/en/circinus*`, `/en/sagitta*`,
+`/en/equuleus*`, `/en/crux*` → numeric slugs.
+
+`html_baseurl` per branch must point at the canonical (numeric or `rolling`),
+not the alias, so `<link rel="canonical">` and the sitemap match what RTD
+serves and crawlers skip the redirect hop.
+
 ## CI
 
 - **vyoslinter** (`doc-linter.py` from the `vyos/.github` repo, run via `lint-doc.yml`) — line length and IP rules, on changed files only.