● PRIVATE — Daily Driver

Antigravity Workers

Production multi-agent system where Claude Code plans, routes, and synthesizes while four specialized Antigravity (AGY) CLI workers do the heavy reading — research, architecture review, code review, and whole-codebase analysis — each returning a hard-capped, structured report. Migrated from Gemini CLI to the AGY invoker.

BashClaude CodeAntigravity CLIPythonJSONL

4Worker Agents

54/54Tests Passing

400-600Word Output Cap

AGYCLI Invoker

// Context

Claude Code's context window is the scarce resource in agentic coding sessions. Whole-repository analysis, large documentation synthesis, and second-opinion reviews burn tokens that the orchestrating agent needs for planning and synthesis. The worker pool started on Gemini CLI, then migrated to the Antigravity (AGY) CLI — a local, API-key-free binary with its own large context window and cross-session memory. The missing piece was a disciplined delegation layer that keeps Claude in charge and keeps worker output cheap.

// What I Built

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Reusable worker wrapper: Single Bash entrypoint (agy-worker.sh) that loads a role's system prompt, selects its model, runs agy headless in read-only plan mode, enforces a watchdog timeout (macOS has no timeout binary), and logs every run as JSONL — timestamp, worker, task, model, duration, exit code.

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Four role-specialized workers: agy-research (repo/docs analysis), agy-architect (design and migration review), agy-reviewer (severity-tagged findings with an APPROVE/WARN/BLOCK verdict), agy-longcontext (whole-codebase questions). Each role file defines a strict output contract capping responses at 400-600 words.

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Thin Claude Code subagents + routing skill: Four Haiku-powered relay subagents symlinked into ~/.claude/agents, plus the Antigravity-worker (gemini-delegate) skill with an explicit routing table, user-visible 'Delegating to agy-X...' status messages, and parallel dispatch rules. Idempotent installer with uninstall and settings.json backup.

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Model fallback chain: Roles target AGY's primary model with automatic single-retry fallback on 429 capacity errors or removed preview models. Priority: env override → role file fallback → default pairing heuristic.

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Dual-side observability: Worker-side JSONL log records every execution; a Claude Code PostToolUse hook adds orchestrator-side entries with session ID and working directory. A logs subcommand renders delegation history in one line per run.

// Architecture

Claude Code (orchestrator)→Antigravity-worker routing→thin Haiku subagent

→agy-worker.sh role "task" --dir→agy (read-only plan mode)→capped report back

workers read a lot, return a little — the token budget is the contract

// Key Engineering Decisions

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Workers are read-only by construction: Every worker runs with --approval-mode plan: AGY can read the workspace but never edit or execute. Claude remains the only writer, which eliminates an entire class of multi-agent write conflicts without coordination machinery.

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Pass pointers, not content: Directories go to workers via include flags; file contents are never pasted into prompts. The worker reads sources itself inside its own large context window, so delegation cost on the Claude side stays near-constant regardless of input size.

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Output contracts over post-processing: Each role prompt hard-caps response length and prescribes structure (findings lists, severity scales, verdict lines). The relay subagents forward output instead of re-processing it — relays run on Haiku and stay nearly free.

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Treat capacity errors as routine: Free-tier models intermittently return 429 'no capacity'. The wrapper detects quota and unknown-model errors in stderr and retries once on the role's fallback model — production resilience for preview-model churn at zero config cost.

// War Story

During end-to-end validation, the review worker kept timing out while other workers succeeded. Root cause was two layers deep: a broken global Gemini CLI BeforeTool hook (calling python on a macOS system that only ships python3) was silently blocking every file read in headless mode — workers degraded to guessing from file names instead of failing loudly. Fixing the hook and adding the model fallback chain took the suite from intermittent failures to 54/54. The later migration from Gemini CLI to the AGY invoker reused the same wrapper contract, so the worker pool swapped engines without touching the routing or observability layers.