Antigravity Delegate

antigravity-delegate (promoted cheap lane — k=5 gate passed)

Delegates a bounded mechanical subtask to Google Antigravity CLI (agy, installed 1.0.10+). Status is honest and load-bearing:

• Evidence: n=1 capability + k=5 reliability. Scoped-edit + no-commit compliance probe passed 2026-07-10 (mc11); the pre-registered k=5 reliability gate passed 5/5 on 2026-07-11 (fresh sandbox per trial, planted decoy untouched, planted judgment question escalated verbatim and not acted on, zero git ops every trial) — recorded as mc12_antigravity_k5_reliability in fable-method-harness/benchmarks/model_compatibility_cases.yaml. Orchestrators may route bounded mechanical work here without an explicit user ask, same as codex-delegate / claude-cheap.
• Scope honesty. k=5 covered ONE fixture shape (scoped edit + decoy + escalation). New task shapes (multi-file transforms, large briefs) deserve their own n=1 probe before heavy routing.
• Replaces nothing. The dead gemini lane's use-cases were rerouted to claude / codex / claude-cheap (splitter 0.3.0). This lane is an alternative cheap executor alongside them.

Invocation contract (discovered empirically, mc11)

Four non-obvious facts, all mandatory:

1. --print mode is plan-only by default and exits 0 SILENTLY without editing. You MUST pass --mode accept-edits for the agent to touch files.
2. --dangerously-skip-permissions is required ALONGSIDE --mode accept-edits: the default tool permission is request-review, which a non-interactive --print run cannot answer (mc11 raw log) — only ever combine it with a narrowly-granted sandbox workspace.
3. The workspace must be granted with an absolute path via --add-dir.
4. Auth lives at ~/.antigravity_cockpit/credentials.json; when it is missing/expired agy hangs or errors — re-auth by running agy interactively once (browser flow). Never attempt to paste OAuth codes non-interactively.

Canonical invocation (or use scripts/run_agy.sh, which wraps all of it and adds: agy pre-flight check; --verify-file <path> / --verify-sentinel <string> result-contract enforcement — exit 3 when agy claims success without producing the named output (F13 "liar mode"); auth/quota classification — exit 4 with a re-auth hint when a NONZERO agy exit matches credential/rate-limit signatures, never reclassifying a success. Hardened 2026-07-14, 17-case regression suite in tests/test_run_agy.sh incl. a glob-decoy case; caveat: agy may natively exit 2/3/4 — disambiguate wrapper-injected codes by the stderr line, not the number alone. Note mc12's k=5 was measured on the pre-hardening wrapper — additions are additive and a post-hardening n=1 mc11-fixture smoke passed with the verify flags exercised):

timeout 300 agy --print \
  "Read .ai/agy_task_<NNN>_<slug>.md in this workspace and execute it
   verbatim; write the result summary to the path it names." \
  --add-dir "<ABSOLUTE workspace path>" \
  --mode accept-edits --dangerously-skip-permissions \
  --print-timeout 240s \
  --log-file .ai/agy_log_<NNN>_<slug>.txt

Hard rules (same spine as codex-delegate; never optional)

• Only bounded mechanical work: transcribe, reformat, apply-a-stated- pattern, scoped single-purpose edits with a runnable acceptance check.
• Never honesty-critical output (reviews, "all green" verdicts, spec-discrepancy calls, completion claims), governance/security surfaces, or ambiguous specs — cheap-tier guardrails per fable-method-harness/core/model_routing_playbook.md apply verbatim.
• Classification stays with the orchestrator — this lane never reclassifies or extends its own scope; uncertainty escalates instead.
• Brief-first: write .ai/agy_task_<NNN>_<slug>.md (same shape as codex briefs — scope-confirmation block first, files in/out of scope, acceptance checks, result path .ai/agy_result_<NNN>_<slug>.md).
• No structured-output flag exists in agy — the result-summary md IS the machine-readable contract; the brief must cap it at <=250 words.
• agy never commits; the orchestrator reviews the diff, runs the acceptance checks itself, and owns staging/commit ("delegate returned" is a mandatory review trigger).
• Every run in a sandbox or scoped workspace — grant --add-dir to the narrowest directory that contains the task.

Promotion gate — MET 2026-07-11

The pre-registered multi-trial reliability pass (k >= 5, planted decoy + planted judgment question that must be escalated) ran 2026-07-11: 5/5 PASS, deterministic grader, criteria frozen before any run. Evidence: mc12_antigravity_k5_reliability (fable-method-harness) + operator audits/harness-optimization-2026-07/agy-k5-20260711/ (pre-registration, results.json, RESULTS.md). The lane is therefore orchestrator-routed; the hard rules above are unchanged and permanent.

See also

• mc11 / mc12 (evidence + probe artifacts: operator audits/harness-optimization-2026-07/agy-probe-20260710/ and agy-k5-20260711/)
• agent-task-splitter 0.3.1 reroute table (why gemini's use-cases did NOT move here; 0.3.1 is the release whose antigravity row records this lane's promotion)
• codex-delegate (the contract this skill's brief shape ports from)
• fable-method-harness/core/model_routing_playbook.md (tier guardrails)