/antigravity — Project Environment Sync for Google Antigravity

Make this project's governance fully available to Antigravity, from whatever state it's in now. Idempotent: first run sets everything up; later runs sync only what changed and report what's new.

Standing caveat this skill must carry into its report: on 2026-08-15, Antigravity with all rules installed on disk (doctor 3/3) still ignored them and mis-reported .claude/rules/ as its own loaded context. Files present on disk and rules reaching the model's context are two different claims — this skill can verify the first, only the user can verify the second (Phase 7's verification step).

Gates (binding in every posture — violating any is a failed run)

1. Docs before build. The live docs check (Phase 3) runs BEFORE any sync work. Antigravity's mechanics drift between runs — its docs tree gained Hooks and per-surface (app/IDE/CLI) sections after Soloship's target was built. Building from remembered facts and checking docs afterward is the failure class this ordering prevents. The report records the docs-check date.
2. Sources are read-only. CLAUDE.md, AGENTS.md, .claude/rules/, .claude/settings.json, .mcp.json are inputs. Never edit or trim them to fit the target.
3. Prefer the installer over hand-rolling. Soloship HAS an antigravity target: npx soloship init --agent antigravity / npx soloship upgrade --agent antigravity, plus the global plugin sync (npm run antigravity:install-local from the Soloship repo, landing in ~/.gemini/config/plugins/soloship). Run those — don't reimplement them (Antigravity itself once proposed rebuilding this installer because it didn't look for it; don't repeat that).
4. Real copies, never symlinks. ln -s ../.claude/rules .agents/rules makes Soloship's installer write future Antigravity-only rules straight into .claude/rules/ (verified against installRulesAt(), 2026-08-15).
5. Syncing config does not certify the tool. The final report must say so and point to the workspace's certification battery if one exists (default location: docs/testing/model-certification/SOP.md).

Phase 1 — Discover the source surface

Inventory: CLAUDE.md, AGENTS.md, every .claude/rules/*.md, .claude/settings.json hooks, .mcp.json, existing .agents/ config (rules/, hooks.json), ~/.gemini/config/plugins/soloship (global plugin, with its syncedAt), ~/.gemini/GEMINI.md (user-global rules), and Soloship presence (.soloship/version). Run npx soloship doctor and record the antigravity lines — the required items are .agents/rules/, .agents/hooks.json, and the global plugin.

Phase 2 — What's new since last run

State lives at .ai/sync-state/antigravity.json: { "syncedAt": ISO-8601, "files": { "<source path>": "<sha256>" } }.

Hash every source (shasum -a 256), diff against the manifest: new / changed / removed / unchanged. No manifest = first run, say so. Removed sources: remove their .agents/rules/ counterparts after verifying the file really derives from the removed source.

Phase 3 — Live docs check (BEFORE any sync work)

Fetch Antigravity's current docs — start at https://antigravity.google/docs/getting-started and follow the nav (as of 2026-08: /docs/rules-workflows/, /docs/ide/rules/, /docs/mcp/, /docs/agent-settings/, /docs/permissions/, /docs/hooks/). If URLs moved, search.

Confirm before acting: rules directory (.agents/rules/) and activation modes unchanged; whether project-level GEMINI.md still matters alongside AGENTS.md; MCP config location and schema for the surface the user actually uses (the docs tree has separate MCP pages for the app, IDE, and CLI); and whether the Hooks docs describe capabilities that could carry more of the Claude Code / Soloship gates.

This phase outputs the verified mapping Phase 4 executes, plus a numbered manual-steps list written for a non-coder — exact menu path, exact value, one line on why. Two settings always get an explicit recommendation with reasoning:

• Terminal policy: recommend NOT Turbo (auto-executes commands; an uncertified agent with Turbo is unauthorized-write-by-default).
• Review triggers: recommend Request Review (or the strictest available) until the tool passes certification.

Phase 4 — Sync (per Phase 3's verified mapping)

1. Installer first: init/upgrade --agent antigravity, then the global plugin sync if the Soloship repo is on this machine. Re-run npx soloship doctor — antigravity must be 3/3. Doctor output is the evidence; paste the relevant lines in the report. (1/3 with only the global plugin present means the per-project .agents/ directory is missing — the installer creates it.) If Phase 3 found the installer's output no longer matches what Antigravity reads, stop and surface that as a Soloship bug instead of patching around it.
2. Close the drift gap the installer misses: diff .claude/rules/ against .agents/rules/ by filename AND content hash; copy any rule absent or stale, byte-identical. List every file moved — each is a candidate to fold into src/rules.ts (suggest it; the change belongs to the Soloship repo).
3. Project without Soloship: create .agents/rules/ and copy all .claude/rules/*.md verbatim. Confirm root AGENTS.md exists (Antigravity reads it natively); report a gap rather than inventing one. Do not create GEMINI.md unless Phase 3 found the project-level file still meaningful alongside AGENTS.md.
4. Hooks: .agents/hooks.json comes from the installer. If Phase 3 found new hook capabilities, propose mappings for more of the Claude Code / Soloship gates in the report. Every gate with no counterpart is listed as protection absent in Antigravity.

Phase 5 — MCP servers

If .mcp.json exists: list servers by name, ask the user which to make available in Antigravity (multi-select). Configure them per the location and schema verified in Phase 3. Secrets: placeholder plus a manual step unless the target file is confirmed outside the repo or gitignored.

Phase 6 — Verify, record, commit

• npx soloship doctor 3/3 on antigravity, file counts match the delta, every copied rule content-identical to source (shasum both sides).
• Write the manifest to .ai/sync-state/antigravity.json.
• Commit generated .agents/ files per project conventions (worktree rules apply).

Phase 7 — Report (always, in this order)

1. Docs-check date + anything that changed in Antigravity's mechanics since the last run.
2. Delta since last run (or "first run — full setup").
3. Synced: what Antigravity now gets (doctor lines + drift-gap list + plugin syncedAt).
4. Protections absent in Antigravity: every hook/gate with no counterpart, named, with what it guarded — plus any hook proposals from the new docs.
5. Manual steps: the numbered list from Phase 3, including the terminal-policy and review-trigger recommendations.
6. MCP: mirrored / skipped / placeholders.
7. Injection verification (user-run, in Antigravity): files on disk don't prove rules reach the model. Give the user this exact check to run in a fresh Antigravity session after a full app restart: ask "Read the file at .agents/rules/plan-claim-verification.md and tell me what it says. Separately: what governance rules do you have loaded right now, and from where?" — if it can read the file when pointed at it but doesn't spontaneously know .agents/rules/ exists, the injection isn't working (observed 2026-08-15).
8. Certification reminder: config synced ≠ tool trusted — run the battery SOP before granting write access; until then, proposal-only.