Model committee fable

Model Committee (Fable-chaired)

Run GPT-5.6 "Sol" and Claude Opus 5 as a deliberating committee with Fable 5 as the chair. Keep the line to $model-council-voting sharp: a council measures independent disagreement, while this committee deliberately exposes each member to the other's argument and returns one decision.

Read references/protocol.md completely before running a committee. It carries the use-case gate, the brief template, the three round contracts, the decision rule, and the decision.md schema.

Fable chairs here because the heavy reasoning is already spent inside the members' three rounds and what remains is mostly mechanical — a lean chair is a deliberate cost choice, and being neither member it cannot vote its own prior a third time. Fable being a Claude-family model, a Codex session reaches it through the bundled claude-member.sh. Siblings: model-committee (Opus 5 chairs) and model-committee-sol (GPT-5.6 "Sol" chairs, with the GPT member dropped to gpt-5.6-terra so the chair is not also a member).

Gate the workflow

Run only when the user invokes $model-committee-fable or asks for a Fable-chaired Sol / Opus deliberation. The external calls draw plan credits or API spend on both providers — surface that and get confirmation unless the user has already accepted it. Apply the protocol's use-case gate first; if the task does not qualify, name the right alternative and call no model.

Before the first call:

1. Confirm the decision that must be returned.
2. Confirm the material may be sent to both providers.
3. Precommit the evaluation criteria, weights, and tie rule.

Sandbox constraint — read before the first call

scripts/codex-member.sh shells out to a nested codex exec process. Confirmed by direct reproduction (July 2026, both hosts this repo runs on): a codex exec process running under any sandbox mode cannot spawn a working nested codex exec child — it fails immediately with Error: failed to initialize in-process app-server client: Operation not permitted (macOS) or Read-only file system (Linux). This is structural, since the OS sandbox applies transitively to the whole process tree, and bypass flags on the nested call do not fix it. Running non-interactively (approval: never in your own session banner), this call cannot succeed — report the failure rather than fabricating the GPT member's response yourself. If interactive, request escalation (sandbox_permissions: require_escalated) for that one call.

scripts/claude-member.sh shells out to claude -p, a different binary, so it does not hit the identical codex exec IPC failure — but under workspace-write sandbox its outbound network call was observed to hang rather than complete, network access being restricted by the sandbox. That observation is less rigorously isolated than the codex-member.sh one; treat a hanging claude-member.sh call the same way and escalate or move to an unsandboxed session. It carries both the Opus member and the Fable chair here, so a hang blocks two of the three seats.

Preflight members and chair

Resolve SKILL_DIR as the directory containing this SKILL.md, then run:

"$SKILL_DIR/scripts/codex-member.sh" --check
"$SKILL_DIR/scripts/claude-member.sh" --check

Default pins:

• GPT member: gpt-5.6-sol (reasoning effort: xhigh)
• Claude member: claude-opus-5 (reasoning effort: high)
• Chair: claude-fable-5 (Fable 5), reached through claude-member.sh

These are exact pins, not moving aliases. If one is unavailable, report it and ask whether to stop or use a named replacement — never substitute silently.

Run the committee

Create a temporary working directory such as .committee-tmp/<slug>/. Follow the protocol's prompt contracts and produce these artifacts:

brief.md
round-1-gpt.prompt.md       round-1-gpt.md
round-1-opus.prompt.md      round-1-opus.md
round-2-gpt.prompt.md       round-2-gpt.md
round-2-opus.prompt.md      round-2-opus.md
round-3-gpt.prompt.md       round-3-gpt.md
round-3-opus.prompt.md      round-3-opus.md
chair.prompt.md             decision.md

Invoke each member through the bundled read-only driver:

"$SKILL_DIR/scripts/codex-member.sh" \
  --prompt-file <prompt.md> --out <output.md> --effort xhigh -C <working-directory>

"$SKILL_DIR/scripts/claude-member.sh" \
  --prompt-file <prompt.md> --out <output.md> --effort high -C <working-directory>

Launch both calls in a round concurrently when the runtime supports it. Sequential execution is acceptable only if the second prompt was frozen before the first result arrived — otherwise round 1 stops being blind.

Chair with Fable, without becoming a third debater

Bundle the brief and all round outputs into chair.prompt.md under the protocol's decision-rule and output contracts, then delegate the post-round-3 chair step:

"$SKILL_DIR/scripts/claude-member.sh" \
  --prompt-file chair.prompt.md --out decision.md --model claude-fable-5 -C <working-directory>

Chairing is procedural: validate the round outputs against the protocol's schemas, aggregate the predeclared weighted scores, apply the precommitted tie rule, and synthesize only components both revisions explicitly marked compatible. Never introduce a new substantive option, and never break a tie by confidence, eloquence, or model identity. If the evidence stays genuinely unresolved, return the exact fork to the user; a forced but unsupported answer is not committee consensus.

A lean chair is likelier to defer where it should synthesize, so check its arithmetic against the round-3 score tables and confirm the decision matches the precommitted rule before delivering — the mechanical steps are exactly where a lightweight chair needs verifying.

Deliver

Return a compact decision record containing:

1. use case and why committee treatment was justified;
2. decision and decision rule (note that Fable 5 chaired);
3. strongest reasons and evidence;
4. what changed during deliberation;
5. surviving dissent or uncertainty;
6. implementation or verification next step.

Delete .committee-tmp/ after delivery unless the user wants the full transcript kept. Implement only once the decision is accepted.