Context Shunt

Context Shunt — Read Cheap, Keep Context Small

Reading big files into context is the most expensive thing an agent does for the least reasoning value. The shunt hands those reads to a cheap worker model (bulk-read) that answers a question about the files and returns a compact summary. The raw bytes never enter this session's context.

This is orthogonal to whole-turn routing (srooter / route-task): those pick the model for the turn; the shunt trims what a tool call pulls into context when the turn is legitimately here.

Decision: read raw, shunt, or graph?

• Editing this exact file — read it raw. You need every line; never edit against a summary.
• A fact/answer across large or many files — bulk-read "<question>" file....
• A code symbol (function/class/route) — get_code_snippet(qualified_name): free and exact.
• Small file (under threshold) you need in full — read it raw.

A shunt answer is for understanding, not for producing a diff.

Usage

bulk-read "how does token refresh work?" src/auth/session.ts src/auth/refresh.ts
bulk-read "which config keys are read at startup?" $(git ls-files 'config/*.yaml')

bulk-read prints structured bullets citing path:line, or NOT FOUND IN PROVIDED FILES. A token-savings report goes to stderr.

Configuration

Env vars or ~/.claude/shunt.conf (see templates/shunt.conf):

• SHUNT — on/off master switch for the PreToolUse hook.
• SHUNT_MIN_LINES — large-read threshold (default 350).
• SHUNT_MODE — suggest (default) / block / off for the hook's large-read action.
• SHUNT_GRAPH_NUDGE — on/off once-per-session graph nudge.
• SHUNT_MODEL — worker command (default deepseek --flash; also gemini-api --flash-lite, qwen3, glm).

The context-shunt-gate PreToolUse hook enforces the thresholds; this skill tells you when to reach for bulk-read yourself.