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FabledScribe/plugin/hooks/scribe_tool_rules.sh
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bvandeusenandClaude Opus 5 2ee24b9d2b
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feat(rules): rules before tools — a PreToolUse arm keyed on the action (#3476)
The only just-in-time rule surface was registered on `Write|Edit` and queried
with `code or path`, so a rule could be retrieved at the moment of a code
write and nowhere else. Every rule about which tool to reach for — don't curl
the forge, don't stand up a stack, don't run the suite locally, don't branch —
was unreachable exactly when it mattered, and residency in the always-on
preload was the only surface it had. That is the pressure that grew the
resident set to 31 against #3089's ceiling of ~23; it was never a judgment
anybody made.

A reflex generates no query, so an instruction to check the rules cannot catch
one. A mechanical trigger can: the tool call IS the query, and a reflex has to
become a tool call before it can do anything.

`build_tool_rule_hint` is deliberately tool-agnostic — a name and a string —
so widening the matcher later is a hooks.json edit with no server change. The
hook starts on Bash, which is where the action reflexes live.

The two pre-tool arms share ONE session ledger of already-named rules
(`<state>/<sid>.rules.ids`). Two ledgers would mean a rule named by one arm
gets re-offered by the other, and the hint that fires most often is exactly
the one that must not repeat itself. A test asserts both scripts build the
same path, and another checks the shell hook and the Python route agree on
every query-arg name (rule 33) — a rename there fails silently, looking like
a surface that never finds anything rather than a broken one.

Deliberately silent on outage, unlike the prior-art hook: a write is
occasional, a Bash call is not, and an outage line before every command is
what gets a channel muted.

`tier="conditional"` matches the write arm and is the transition point — an
always-on rule is already resident, so re-tier one and it starts arriving here
instead of in every session's preamble. `pre_tool_rule` joins RANKED_SOURCES:
this arm chose what it showed, so a pull can settle whether the choice landed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011cPyzNnegXHr5iRMzzy5KJ
2026-09-02 23:31:22 -04:00

117 lines
5.1 KiB
Bash

#!/usr/bin/env bash
# Scribe — PreToolUse rule arm for ACTIONS (#3476).
#
# The sibling of scribe_prior_art.sh. That hook is registered on Write|Edit and
# asks "what is recorded about the file being written". This one asks "does a
# standing rule speak to the command about to be run" — the question nothing
# could ask before, and the reason every rule about which tool to reach for had
# to live in the always-on preload instead.
#
# WHY A HOOK AND NOT AN INSTRUCTION. A reflex generates no query (note #3089):
# you reach for `curl` confidently, with no moment of doubt, so a surface that
# waits to be asked never fires. Here nothing is asked — the tool call IS the
# query, and the reflex has to become a tool call before it can do anything.
#
# SILENT ON OUTAGE, deliberately, unlike the prior-art hook. A write is
# occasional; a Bash call is not, and an "instance did not answer" line before
# every command is the noise that gets a channel muted. scribe_prior_art.sh
# still speaks for both when the instance is down.
#
# Env:
# SCRIBE_URL / SCRIBE_TOKEN override for the settings.json dogfooding path.
command -v jq >/dev/null 2>&1 || exit 0
command -v curl >/dev/null 2>&1 || exit 0
# PreToolUse delivers { session_id, cwd, tool_name, tool_input: {...}, ... }
event=$(cat 2>/dev/null || true)
tool_name=$(printf '%s' "$event" | jq -r '.tool_name // empty' 2>/dev/null) || exit 0
session_id=$(printf '%s' "$event" | jq -r '.session_id // empty' 2>/dev/null) || session_id=""
event_cwd=$(printf '%s' "$event" | jq -r '.cwd // empty' 2>/dev/null) || event_cwd=""
[ -n "$tool_name" ] || exit 0
# The action, as text. `.command` is Bash's field; the fallbacks let the matcher
# in hooks.json widen to other tools without this script changing — which is the
# whole reason the server side takes a name and a string rather than a schema.
command_text=$(printf '%s' "$event" | jq -r '
.tool_input.command //
.tool_input.url //
.tool_input.prompt //
empty' 2>/dev/null) || command_text=""
[ -n "$command_text" ] || exit 0
# shellcheck source=plugin/hooks/scribe_defs.sh
. "$(dirname "${BASH_SOURCE[0]}")/scribe_defs.sh"
# scribe_config, not a hand-rolled pair of parameter expansions: it also treats
# an UNEXPANDED `${...}` placeholder as unset, which would otherwise be sent as
# a garbage Bearer token and 401 on every call (#2198's class).
scribe_config || exit 0
# Bounded before encoding: a heredoc or a pasted script can be enormous, and
# the verb and its target — the part a rule is about — sit at the front. The
# server bounds it again; this keeps a huge payload off the wire in the first
# place. `head -c`, never `cut -c`: cut truncates each LINE and caps nothing.
command_text=$(printf '%s' "$command_text" | head -c 2000)
# -sRr, never -rR: jq -R without -s reads LINE BY LINE, so a multi-line command
# would encode per line and join with raw newlines — an invalid URL.
cmd_enc=$(printf '%s' "$command_text" | jq -sRr '@uri' 2>/dev/null) || exit 0
tool_enc=$(printf '%s' "$tool_name" | jq -sRr '@uri' 2>/dev/null) || exit 0
repo_q=""
lookup_dir=${event_cwd:-${CLAUDE_PROJECT_DIR:-$PWD}}
repo_remote=$(git -C "$lookup_dir" remote get-url origin 2>/dev/null || true)
if [ -n "$repo_remote" ]; then
repo_enc=$(printf '%s' "$repo_remote" | jq -sRr '@uri' 2>/dev/null) || repo_enc=""
[ -n "$repo_enc" ] && repo_q="&repo=${repo_enc}"
fi
# THE SHARED SESSION LEDGER, and the thing most worth getting right here.
#
# scribe_prior_art.sh keeps the rules it has already named in
# <state>/<sid>.rules.ids and passes them as exclude_rule_ids. This hook reads
# and appends to that SAME file rather than keeping its own: two ledgers would
# mean a rule named by one arm gets re-offered by the other, and the hint that
# fires most often is exactly the one that must not repeat itself.
#
# The directory keeps the prior-art name on purpose — renaming it would orphan
# every live session's state for a cosmetic gain.
state_dir="${TMPDIR:-/tmp}/scribe-priorart"
mkdir -p "$state_dir" 2>/dev/null || true
rulefile=""
rule_exclude_q=""
if [ -n "$session_id" ]; then
safe_sid=$(printf '%s' "$session_id" | tr -c 'A-Za-z0-9._-' '_')
rulefile="$state_dir/${safe_sid}.rules.ids"
if [ -f "$rulefile" ]; then
rule_seen=$(tr '\n' ',' < "$rulefile" 2>/dev/null | sed 's/,$//')
[ -n "$rule_seen" ] && rule_exclude_q="&exclude_rule_ids=${rule_seen}"
fi
fi
# `|| exit 0` here, unlike the prior-art hook: there is no local arm whose
# finding would be discarded, and an outage line before every command is worse
# than silence. See the header.
body=$(curl -fsS --max-time 5 \
-H "Authorization: Bearer ${token}" \
"${url%/}/api/plugin/tool-rules?tool=${tool_enc}&command=${cmd_enc}${repo_q}${rule_exclude_q}" 2>/dev/null) || exit 0
context=$(printf '%s' "$body" | jq -r '.context // empty' 2>/dev/null) || exit 0
[ -n "$context" ] || exit 0
# Remember what was named so it is not repeated this session.
if [ -n "$rulefile" ]; then
printf '%s' "$body" | jq -r '(.rule_ids // [])[]?' 2>/dev/null >> "$rulefile" || true
fi
jq -cn --arg ctx "$context" '{
hookSpecificOutput: {
hookEventName: "PreToolUse",
additionalContext: $ctx
}
}' 2>/dev/null || true
exit 0