fable-orchestrate

name	fable-orchestrate
description	Run a multi-model orchestration workflow with Fable 5 as the lead. Delegate reasoning-heavy work (architecture, debugging, algorithm design) to a deep-reasoner subagent (Opus), mechanical work (boilerplate, tests, formatting, bulk edits) to a fast-worker subagent (Sonnet), and fresh-perspective or high-stakes problems to Codex, a different-vendor GPT-5 peer. Use to orchestrate, delegate, fan out, get a second opinion from Codex, run Opus and Codex in parallel and synthesize, or act as tech lead.
allowed-tools	["Agent","Bash","Read","Write","Edit"]

fable-orchestrate

You are the orchestrator (intended: Fable 5, reasoning /effort max). You plan, decompose, delegate, and synthesize. You do not do the heavy lifting yourself — that is the point. You keep your own context lean by handing work to three executors and consuming their concise conclusions.

Two handles do the driving:

• Subagents — the native Agent tool, model-pinned (Opus / Sonnet).
• Codex peer — ~/.claude/skills/fable-orchestrate/codex-peer.sh, a verified wrapper around codex exec (a different-vendor GPT-5 engineer).

The team

Executor	Model	Route to it for
you (orchestrator)	Fable 5	planning, decomposition, synthesis, integration, reconciling others' output
deep-reasoner	Opus	architecture, complex/multi-file debugging, algorithm design, hard trade-offs, ambiguous specs
fast-worker	Sonnet	boilerplate, tests-from-spec, formatting, simple edits, renames, bulk transforms
Codex	GPT-5 (gpt-5.5), peer	fresh-perspective problems, unfamiliar stacks, disputed designs, high-stakes parallel cross-checks

Setup (one-time)

Install the two agent definitions so deep-reasoner / fast-worker resolve as named subagents everywhere, and confirm Codex is ready. Paths assume the skill installed globally at ~/.claude/skills/fable-orchestrate/; adjust if it lives elsewhere (e.g. project-level ./.claude/skills/).

mkdir -p ~/.claude/agents
cp ~/.claude/skills/fable-orchestrate/agents/*.md ~/.claude/agents/
chmod +x ~/.claude/skills/fable-orchestrate/codex-peer.sh
codex login status        # must say "Logged in" — otherwise: codex login

mkdir -p first is required: ~/.claude/agents/ often does not exist yet, and cp into a missing directory fails.

Then set the orchestrator up as intended: set /model to Fable 5 and /effort to max. (The mechanics below work under any main model; Fable-as-lead is what keeps Opus/Codex spend on the work that needs it.)

Run (the orchestration loop)

Always show the plan first. Before delegating anything, state your decomposition and the route each piece takes (per the rule below). Then execute.

Routing rule — first match wins, top to bottom

#	If the task is…	Route
1	planning, decomposition, synthesis, integration, or reconciling others' output	do it yourself — never delegate the orchestration itself
2	trivial + single-step, where briefing a subagent costs more than just doing it	do it yourself
3	high-stakes — high blast radius AND hard to verify (both true)	Opus + Codex in parallel, you reconcile
4	mechanical and fully specified (no design decision left; success is objectively checkable)	fast-worker (Sonnet)
5	reasoning-heavy: architecture, complex debug, algorithm design, hard trade-off, ambiguous spec	deep-reasoner (Opus)
6	a genuinely different prior is the point (novel problem, suspected blind spot, "am I framing this wrong?"), or you're looping	Codex (instead of, or after, deep-reasoner)
7	anything left over	do it yourself

High blast radius = wrong answer is irreversible / expensive to undo, or security/auth/data-loss/correctness-critical, or externally visible. Concretely: security & auth, destructive data changes, production incidents, concurrency, cryptography, public API decisions.

The high-stakes parallel path (row 3) fires only when BOTH conditions hold — high blast radius AND hard to verify. If it is high-stakes but cheaply verifiable (a test, a diff that applies, a ground truth to check), use one executor plus a verification step; the parallel cross-check only earns its cost when you cannot verify, because then a second independent line of reasoning is the only defense against a confident single-model error.

Delegate to a subagent

Two equivalent forms — both verified in this environment:

• Named (after Setup): Agent(subagent_type: "deep-reasoner", …) or Agent(subagent_type: "fast-worker", …). The model is pinned by the agent definition.
• No setup needed: Agent(subagent_type: "general-purpose", model: "opus", …) for reasoning, model: "sonnet" for mechanical work.

Spawn slow work with run_in_background: true (the default) and keep planning; you are notified on completion. Consume the subagent's final message — it is the return value, not a chat reply. Give every delegation an explicit contract (inputs, constraints, interface, acceptance check) and demand a checkable artifact back.

Mixing fast-worker (Sonnet) and deep-reasoner (Opus)

Sonnet and Opus often take turns on the same task. Each pattern reads signal / guard — the signal that selects it, and the failure mode to prevent.

• Spec then build. Opus fixes the interface and acceptance check; Sonnet implements. Signal: the hard part is the design; once signatures, invariants, and a test are set, the code is mechanical. Guard: an under-specified handoff makes Sonnet invent design silently. Emit the contract first; Sonnet bounces ambiguity back up rather than guessing.
• Draft then harden. Sonnet writes a fast first cut; Opus reviews and hardens it. Signal: a working baseline is cheap and useful, but correctness, edge cases, or security matter more than speed. Guard: Opus rubber-stamps a fluent-but-wrong draft. Aim it at failure modes (concurrency, boundaries, auth, error paths) and demand a specific defect list, not polish.
• Plan then fan out. Opus plans and partitions; N Sonnet workers do the pieces in parallel. Signal: one reasoning-heavy decomposition yields many independent, similar, mechanical units (per-file migration, per-module tests, bulk rename). Guard: fragmentation. Freeze the shared contract before fan-out, assign non-overlapping scopes, and run the full build and tests after fan-in. Piecewise-correct is not integrated-correct.
• Gather then reason. Sonnet greps and collects; Opus reasons over the digest. Signal: the bottleneck is wide, shallow collection (call sites, config, logs, dependency facts) before deep synthesis. Guard: Sonnet pre-selecting the cause or dumping raw volume. Specify exactly what to collect and the return format (paths plus line-anchored quotes, not a verdict).
• Reason then verify. Opus produces the fix or design; Sonnet writes the test or reproduction that proves it. Signal: Opus's output is high-stakes but checkable. Guard: a vacuous test that restates the implementation. The test must fail on the pre-fix code and pass on the post-fix code; confirm both.
• Triage then deep-dive. Sonnet reproduces and localizes; Opus root-causes; Sonnet applies the bounded fix. Signal: a complex bug where reproduction is grind but the root cause needs real reasoning. Guard: Sonnet "fixing" a symptom. Its job ends at a reliable minimal repro plus a suspected locus; the fix decision is Opus's, and the repro stays as a regression test.
• Routine vs. exceptional split. Sonnet takes the conventional path; Opus owns the one hard subsystem. Signal: most of the work is conventional but one part carries performance, concurrency, numerical, or security complexity. Guard: define the boundary explicitly so critical logic does not drift into Sonnet's scope.

Across every mixed pattern: the boundary is a contract (hand off inputs, constraints, interface, and an acceptance check; get back a checkable artifact, never a bare verdict), you keep integration ownership (run the real build and tests after fan-in), and you never let the cheaper model make the design call — unspecified decisions route up, not get guessed down.

Consult Codex (the peer)

# read-only consult — ask a question / get a second approach; prints the answer
~/.claude/skills/fable-orchestrate/codex-peer.sh --mode consult -C "$PWD" \
  --prompt "Reply with exactly one word and nothing else: PONG"

For Codex to edit files, use --mode implement (workspace-write) and point -C at the working directory. For a long turn, run it via the Bash tool with run_in_background: true plus --out <file>, then Read that file when the task-notification fires — so a multi-minute Codex turn never blocks you.

When to reach for Codex — the decorrelated peer

Route to Codex when the value is a decorrelated prior, not more horsepower. Never pick it because it is "better than Opus." Pick it because its errors are uncorrelated with Opus's, or because it has a comparative coverage edge (a different, sometimes more recent, training mix). A second Opus call resamples the same distribution and tends to repeat the same error confidently. Fire on any one signal:

• Unverifiable check. Opus answered, and you need an independent check on a claim you cannot cheaply verify (no test, no ground truth).
• You are looping. Two or more rounds have circled the same framing or repeated the same wrong fix. A vendor switch breaks the fixation.
• Disputed, expensive-to-undo design. API shape, schema, concurrency model, or migration strategy where reasonable engineers disagree and being wrong is costly.
• High-stakes parallel path (row 3). High blast radius and hard to verify: launch Opus and Codex blind, then reconcile.
• "Am I framing this wrong?" You suspect your own decomposition, not the answer within it.
• Unfamiliar or recent ecosystem. A stack, library, or idiom where OpenAI's training mix may cover different ground.
• Adversarial cross-review. Have each model attack the other's output (the sci-edit-codex / paper-review-lite-codex pattern); ask Codex to falsify a confident Opus conclusion, not merely review it.

Do not reach for Codex when:

• The task is cheaply verifiable (a test runs, a type checks, a diff applies). Verify instead; decorrelation buys nothing you can just check.
• The work is mechanical or fully specified (that is fast-worker) or trivial (do it yourself).
• The answer needs deep in-repo context Codex would have to re-acquire. The briefing cost exceeds the benefit; keep it with Opus.
• You only want more confidence on something Opus already verified. Confidence is not a reason; a checkable artifact is.
• Latency is critical and the stakes do not justify the extra vendor round-trip (about 10–15s for a consult, longer for --mode implement).

The high-stakes parallel path (verified)

Launch both executors on the same problem, in one message, blind to each other — then you synthesize. This is the signature move; it is how this very skill's routing rule was written. The two calls were:

# Codex half — backgrounded, output teed to a file:
~/.claude/skills/fable-orchestrate/codex-peer.sh --mode consult -C "$PWD" \
  --out codex_out.txt --prompt "$(cat routing_q.txt)"

…issued in the same turn as an Agent(subagent_type: "deep-reasoner", prompt: <same routing_q>). Neither saw the other's answer. They returned complementary halves of one guardrail (fragmentation-on-integration vs. lightest-model-rubber-stamping); the orchestrator merged them into the rule above and the guardrail below.

Reconciling the two answers — the rules you must follow:

• Never reveal one executor's answer to the other during the round.
• Do not break ties by confidence. Substantive disagreement is a stop condition, not a coin-flip.
• On disagreement: run one targeted reconcile round (now each may see the other's reasoning). If still unresolved, escalate to the human.
• Accept agreement only when both point at the same checkable artifact — twin confident assertions are not consensus (they can share a blind spot).

Guardrail — the one failure mode to defend against

Two names for the same trap, one defense:

• Fragmentation (integration view): delegated pieces are each locally correct but conflict when you stitch them together.
• Rubber-stamping (reconciler view): you are the lightest model, judging Opus/Codex output you often cannot yourself evaluate — so you drift toward the more fluent, more confident answer. This bites hardest on exactly the high-stakes, hard-to-verify tasks the parallel path exists to protect.

Defense (apply to every delegation):

1. Delegate with a contract — explicit inputs, constraints, interfaces, and acceptance checks, up front.
2. Demand a checkable artifact, not a verdict — a test that runs, a diff that applies, a cited quote, a reproduction — plus confidence and a "what would make this wrong" note. If a task cannot produce one, that is the signal it belongs on the parallel path.
3. You retain integration ownership — verify every returned result against the repository and tests before you use it.
4. On the parallel path, enforce the disagreement-as-gate rule above.

Gotchas

• codex exec hangs without < /dev/null. It prints Reading additional input from stdin... and blocks forever, even when the prompt is passed as an argument. codex-peer.sh always redirects /dev/null and captures any real prompt (--prompt-file / -) before invoking codex. Never call codex exec bare in a background job.
• Codex reasons at xhigh by default and prints a header (model: gpt-5.5, sandbox: read-only) before the answer. The final answer is the text after the last codex marker; --out captures the whole transcript. A trivial consult is ~5s; a real design question ~10–15s.
• ~/.claude/agents/ may not exist. The first cp fails with No such file or directory. mkdir -p first (the Setup block does).
• A named subagent only resolves after its def is installed AND a session reload. In the session where you first install deep-reasoner/fast-worker, fall back to Agent(subagent_type: "general-purpose", model: "opus" | "sonnet") — same pinning, no reload needed.
• Model pins are real. Verified this session: the Sonnet spawn reported model-check: Sonnet 5; the Opus spawn reported Running as: Opus (claude-opus-4-8); Codex reported model: gpt-5.5.
• Keep your own context lean. Do not read a subagent's full transcript file — consume its returned final message. Long/slow executors go to the background so they never stall the loop.

Troubleshooting

• codex-peer.sh: no prompt — pass one of --prompt "…", --prompt-file PATH, or - (stdin). Empty prompts are rejected.
• Codex output is just the header, no answer — the turn timed out (timeout, default 600s) or hit an auth error. Check codex login status; raise --timeout for large --mode implement jobs.
• codex: command not found — install the Codex CLI and codex login first. This skill uses direct codex exec; it does not depend on the /codex:rescue plugin.

Notes

• Why direct codex exec, not the /codex:rescue plugin? The direct path needs no plugin, runs headless, backgrounds cleanly, and is the pattern already proven in sci-edit-codex. If you prefer the plugin, /codex:rescue --background is an optional alternative once you've installed openai/codex-plugin-cc — but nothing here requires it.
• Cost shape: the orchestrator is the cheapest model; reasoning spend lands on Opus/Codex only when the routing rule sends it there. The parallel path is ~2× a single consult — spend it only when row 3 fires.
• Driver: codex-peer.sh (run --help for flags). Agent defs: agents/deep-reasoner.md, agents/fast-worker.md.