docs: automated update - 2026-W19

[camielvs]

Automated draft PR generated by the docs-update skill running against TangleML/tangle-ui. Requires human review before merging.

Source PRs

This PR documents user-facing GA changes from the following merged tangle-ui PRs (week 2026-W19, since 2026-05-01):

PR	Title
#2181	fix: show contextual artifact unavailability message in preview dialog

Source PRs reviewed but not documented

• #2179 (Removes dashboard feature flag) — graduation event, but the existing docs already describe the dashboard as the default home experience, so no doc edits were needed.
• 27 v2-editor PRs — the V2 editor is gated by the v2_editor beta flag (visible only via the EditorVersionToggle). Skipped as beta.
• #2225 — touches input-aggregator (beta flag). Skipped as beta.
• #2241 — adds the new v2_editor beta flag. Not documentable per the skill's src/flags.ts rule (new beta flags aren't documented).
• #2234, #2214–#2224 — analytics instrumentation only. Not user-facing.
• #2212 — internal tooling (auto-docs skill). Not user-facing.
• 6 dependabot PRs — skipped by dependencies label.

Proposed changes

• docs/core-concepts/artifacts.mdx — Document the configurable artifact retention notice and the new contextual "Artifact unavailable" / "Failed to load artifact" inline notices in the artifact preview dialog (from tangle-ui #2181).

Reviewer checklist

• Verified each doc change reflects actual feature behavior
• Checked for any hallucinated or inaccurate descriptions
• Confirmed all internal links resolve to real pages
• Confirmed all images/screenshots exist and are correctly referenced (no broken markdown image tags)
• Confirmed external URLs are correct and not invented
• Reviewed any new pages for correct frontmatter/metadata
• Confirmed any new pages are correctly registered in sidebars.ts and appear in the right category