fable-router

fable-router

README.ko.md

Inspired by gpt-5.6-router, ported to Claude Code. Saves Fable 5 (parent) tokens by routing delegable work stages to Opus/Sonnet/Haiku via the Agent tool's model override.

Flow

1. Gate 1 — pick a PERFORMANCE / BALANCED / TOKEN_SAVER profile (AskUserQuestion)
2. Read-only discovery — Haiku/Sonnet subagents gather only the minimum evidence needed to route
3. Route design — assign the lowest-cost capable model and lowest safe reasoning effort per stage, compare against Fable-direct
4. Gate 2 — explicit route approval, then execution
5. Completion report — actual route, validation results, deviations, residual risk

Changes from the original

• Sol/Terra/Luna remapped to Fable / Opus·Sonnet / Haiku capability floors
• Removed spawn_agent runtime classification (A/B/C) and Codex troubleshooting — the Claude Code Agent tool always supports the model parameter
• Merged references/assets docs into a single SKILL.md
• Added effort routing: the Agent tool has no per-call effort parameter, so the plugin ships worker-low / worker-medium / worker-high / worker-xhigh agent definitions (agents/) and routes effort by subagent_type, composing freely with the model override

Install

Claude Code (plugin marketplace)

/plugin marketplace add KyongSik-Yoon/fable-router
/plugin install fable-router@fable-router

Manual (any Claude Code checkout)

git clone https://github.com/KyongSik-Yoon/fable-router
ln -s "$(pwd)/fable-router/skills/fable-router" ~/.claude/skills/fable-router
# effort-variant worker agents (skip if you only want model routing)
for f in fable-router/agents/*.md; do ln -s "$(pwd)/$f" ~/.claude/agents/; done

Note: the manual install registers workers as worker-low etc. (no fable-router: prefix); the plugin install is the documented path.

Claude Desktop / claude.ai

Upload the skills/fable-router folder (or a zip of it) in Settings → Capabilities → Skills.

Then invoke with /fable-router. Activates only on explicit invocation.

Opus version pin

By default, Opus stages use the Agent tool's opus alias — whatever the harness currently maps it to (the newest Opus). If that version underperforms, pin the version routed Opus stages actually run on (mechanism borrowed from opus-5-router: full model IDs in agent frontmatter beat the alias):

/fable-router opus 4.8      # pin Opus stages to claude-opus-4-8 (also: 4.7, 4.6)
/fable-router opus status   # show the current pin
/fable-router opus default  # unpin (also: opus 5, opus off)

State is the pin file ~/.claude/fable-router-opus-pin (one full model ID). While it exists, Opus stages spawn the pinned workers worker-opus48-* / worker-opus47-* / worker-opus46-* (medium/high/xhigh efforts; the model ID lives in their frontmatter, so the model parameter is omitted). Any other claude-opus-* ID is stored verbatim and passed as the model parameter directly. The pin only swaps which Opus runs Opus stages — capability floors, effort floors, and Sonnet/Haiku/Fable routing are unchanged.

Auto mode

Off by default. /fable-router auto on creates the flag file ~/.claude/fable-router-auto; while it exists, the skill skips the profile and route-approval questions and runs its recommended route (BALANCED unless a profile is named in the arguments) immediately. /fable-router auto off removes the flag. Safety invariants and normal permission prompts still apply.

With the plugin install, auto mode also stops needing /fable-router on every turn: the bundled UserPromptSubmit hook (hooks/auto-route.sh) checks the same flag and injects a routing directive into each turn. The directive tells the router to skip trivial and conversational turns — routing overhead would cost more than it saves there — so short follow-ups stay direct. With no flag the hook exits silently and injects nothing.

Manual installs do not pick up the hook (symlinking the skill registers no hooks). To get it without the plugin, point a UserPromptSubmit hook in ~/.claude/settings.json at your checkout's hooks/auto-route.sh.