feat(content): update Agent Island for 2.1.2

[tristan666666]

Summary

• Refreshes the existing Agent Island source entry for https://github.com/tristan666666/agent-island/releases/tag/v2.1.2.
• Adds current support facts for Claude, Codex, Antigravity, Grok, and Cursor.
• Updates the release source, tags, keywords, distribution wording, and current session/usage capabilities.

I maintain Agent Island. This is a source-backed factual refresh of the existing listing, not a duplicate submission.

Submission Source

• This PR changes exactly one content/<category>/<slug>.mdx file.
• The entry includes source/provenance URLs and practical install/use details.
• submittedBy and submittedByUrl match the PR author.
• No generated output, packages, workflows, or multiple entries were modified.
• No issue is linked because this is a bounded factual refresh to an existing entry.

Schema and Quality Checks

• pnpm validate:content:strict passed.
• No forbidden fields were added.
• Install and usage paths remain practical and complete.

Quality Evidence

• Changed resource: content/tools/agent-island.mdx
• Expected behavior: the existing detail entry reflects the current 2.1.2 provider and monitoring surface.
• Important invariant: Agent Island remains described as a monitoring companion, not a coding agent.
• Backward compatibility: content-only update; no schema or rendering changes.
• No visual impact: the existing content renders through the unchanged resource template.

Validation

• No generation or generated output was committed.
• pnpm validate:content:strict
• The affected MDX source and release links were spot-checked.

[tristan666666]

Updating this for Agent Island 2.1.2, released 2026-08-09.

Gemini CLI is out; Antigravity is in. Google retired Code Assist for individuals on 2026-06-18 and pointed those users at Antigravity, so the slot followed them. Every Gemini* source file is gone in 2.1.2; the provider set is now Claude Code, Codex, Antigravity, Grok and Cursor.

2.1.2 also ships macOS and Windows from the same tag for the first time (AgentIsland-2.1.2.dmg and AgentIsland-2.1.2-win-x64.zip).

Correcting two things in my own earlier note here, since this page is more structured than a one-line list entry and deserves the precision:

• I described this as "one line, one word." It is not — this entry is a full .mdx page and the change touched six places across the frontmatter tags, keywords and prose.
• I posted the same comment twice, 23 minutes apart, from a batch sweep. The duplicate is deleted. Apologies for the noise.

I am the author. A follow-up commit is coming that fixes the remaining version strings this page still carries from 2.1.1.