/architect: Reduce Fable tokens by 80%, Fable orchestrates/reviews, Codex builds

Developer Dan McInerney released Architect Loop, an open-source tool that uses Claude Code as an architect and GPT-5.5 Codex as a builder to run cross-vendor AI development loops on flat-rate subscriptions. The system splits work into isolated lanes with acceptance gates, parallel builders, and judgment sessions, aiming to improve software development throughput without API token costs.

Claude Fable is the architect — it designs every slice, freezes the acceptance gates, and judges the results. GPT-5.5 Codex is the builder and researcher — it does all the engineering and all the web research, in parallel, unattended, for hours. Two Claude Code skills that run this cross-vendor loop on the flat-rate subscriptions you already have — no API keys, no token bills. git clone https://github.com/DanMcInerney/architect-loop cd architect-loop && ./install.sh Windows: .\install.ps1 npm i -g @openai/codex@latest the builder Codex CLI = 0.133 ./install.sh --project installs to the current repo only instead of globally. You need Claude Code https://claude.com/claude-code on any paid plan and the Codex CLI signed into a ChatGPT plan. /architect the build loop /architect-research <what you're considering the research loop /architect runs one work block: judge the last run, spec the next slice, dispatch builders. /architect-research is for when you're still deciding what to build — its cited report feeds the build loop's PRD. One short Fable session per work block — judgment only, it never writes code: Spec + gates first. Fable specs a one-PR slice, splits it into 1–4 lanes with provably disjoint file sets, and commits the acceptance gates to docs/gates/ before any builder starts. Gates are read-only; a builder edit to a gate file fails the slice automatically. Parallel isolated builders. One fresh codex exec xhigh per lane, each in its own git worktree. Builders must argue with the spec before building silent compliance = defect , build only their declared files, and report raw results — they physically can't commit the sandbox protects .git . Fable judges and integrates. It runs the gate commands itself builder claims are hearsay , reads the diff against the spec's intent passing tests ≠ mergeable work , then commits and merges passing lanes. Judgment happens in a fresh session — cross-context review measurably beats same-session review. The repo is the only memory. docs/HANDOFF.md a short table of contents, pruned every session , docs/gates/ , docs/lanes/ , git history. Not in the repo = didn't happen. Supervision built in. Liveness checks on dispatched runs, stall triage diagnose the child process tree, kill the narrowest thing , explicit timeouts on every long command. Scout-first, like the production deep-research systems — no fixed lane taxonomy: A cheap Codex scout maps the topic ~10 searches : canonical terminology, the load-bearing systems and papers, the named people, the topic's natural fault lines. Skipped for comparisons and fact-finds. Fable designs 3–6 topic-specific lanes from the scout's map, drawing per-source-class tactics from a library academic citation snowballing, dependents-not-stars repo evidence, emerging-vs-hype gating, production pattern mining, expert tracking — checked for overlap and gaps before dispatch. Parallel Codex researchers run under hard budgets: search caps, ≤5 subjects per lane, saturation stop, strict findings discipline URL + date- quote + confidence tag; NOT FOUND beats inference; no recommendations . Expert opinion runs as a second wave, roster-seeded by the first. Fable verifies and writes. ≥2 independent sources per load-bearing claim, adversarial falsification searches, citations only from URLs actually fetched — then one author writes one decision-oriented report. Gathering parallelizes; synthesis never does. Each piece is there because evidence put it there full citations in DESIGN.md /DanMcInerney/architect-loop/blob/main/DESIGN.md : - Weak planners hurt more than weak executors — so the strongest model does the design, and builders get exhaustive specs. - Manager + worktree-isolated workers is the measured-best topology for shared-artifact software work; naive shared-file coordination collapses throughput. - Frozen external gates beat trusting the agent — but agents game visible tests and their passing PRs are frequently unmergeable, so the architect also reads the diff. - Memory files rot — so the handoff stays a short map, and detail lives in linked gate/lane files. - Every production deep-research system uses planner-designed decomposition, none uses fixed lanes — so research lanes are designed per topic, after a scout pass. | File | What it is | |---|---| | skills/architect/SKILL.md /DanMcInerney/architect-loop/blob/main/skills/architect/SKILL.md skills/architect/dispatch.md /DanMcInerney/architect-loop/blob/main/skills/architect/dispatch.md codex exec commands, builder block, worktree fan-out, stall triage skills/architect/research.md /DanMcInerney/architect-loop/blob/main/skills/architect/research.md skills/architect/HANDOFF.template.md /DanMcInerney/architect-loop/blob/main/skills/architect/HANDOFF.template.md skills/architect-research/SKILL.md /DanMcInerney/architect-loop/blob/main/skills/architect-research/SKILL.md skills/architect-research/lanes.md /DanMcInerney/architect-loop/blob/main/skills/architect-research/lanes.md tests/validate skills.py /DanMcInerney/architect-loop/blob/main/tests/validate skills.py Do I need API keys? No. Claude Code runs on your Claude plan; Codex CLI on your ChatGPT plan. What does a run cost? Builder/researcher runs draw on your ChatGPT plan's 5-hour and weekly quotas; a multi-hour run is a meaningful fraction of a weekly window. Fable's architect sessions are minutes, not hours. What if a builder wrecks things? Nothing reaches a branch until the architect's tamper, boundary, and gate checks pass — worktrees are discarded and re-dispatched from the freeze commit. Can I watch a run? Yes — every dispatch prints the builder block, so you can paste it into an interactive codex session with /goal instead. Why two skills? Research-grade fan-out costs ~15× chat-level tokens — it should be a deliberate act, not a side-effect of the build loop. MIT