feat(ctx7): coverage extension — fast-libs single source + reminder hook + executor briefs (BDR-078)

- lib/fast-libs.sh: detect/cache-status verbs, JS+Python manifests,
  7-day cache freshness, LC_ALL=C sort — replaces 3 hardcoded lists
  (ship-feature 0c, init-project 5c, onboard 3.5)
- hooks/ctx7-reminder.sh: once-per-session UserPromptSubmit nudge when
  the project carries fast-libs and .ctx7-cache/ is missing/stale
- find-docs: before-writing-code trigger + cache-first rule; dist is
  machine-owned (gitignored) so the durable patch lives in
  install-plugins.sh STEP ctx7 (idempotent, grep-guarded)
- feater/bugfixer briefs: fast-lib docs rule (fresh cache read, else
  2-topic ctx7 fetch, else NOTES cache miss + proceed)
- tests: lib/tests/fast-libs.test.sh (11 checks); shellcheck + full
  make test green (review-guards 5/0)

hooks/ctx7-reminder.sh

@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+# ctx7-reminder.sh
+#
+# UserPromptSubmit hook. When the current project uses fast-moving libs
+# (lib/fast-libs.sh) it injects ONE reminder per session to consult ctx7
+# (find-docs skill) before coding against their APIs, pointing at the
+# .ctx7-cache/ state. Closes the ad-hoc-coding gap: find-docs' description
+# fires on doc *questions* and ship-feature/init-project pre-fetch, but
+# nothing covered a plain "add a useEffect here" prompt (BDR-078; second
+# deliberate ctx7 surface, scoped refinement of BDR-053 single-surface).
+#
+# Soft nudge: always exits 0, never blocks. Stable-tech projects (no
+# manifest, or no fast-lib match) stay silent.
+
+set -euo pipefail
+
+input="$(cat)"
+
+field() { # $1=json key — extracted from hook stdin, empty on failure
+  printf '%s' "$input" | python3 -c \
+    "import sys,json; print(json.load(sys.stdin).get('$1',''))" \
+    2>/dev/null || true
+}
+
+prompt="$(field prompt)"
+case "$prompt" in
+  '<task-notification>'*) exit 0 ;; # harness turn, not a user request
+esac
+
+cwd="$(field cwd)"
+[ -n "$cwd" ] || cwd="$PWD"
+
+# Cheap bail-out before any lib work: no manifest → no fast-libs.
+[ -f "$cwd/package.json" ] || [ -f "$cwd/requirements.txt" ] \
+  || [ -f "$cwd/pyproject.toml" ] || exit 0
+
+# One fire per session: the doctrine holds for the whole session,
+# repeating it on every prompt would be token spam.
+session_id="$(field session_id)"
+sentinel="${TMPDIR:-/tmp}/.ctx7-reminder-${session_id:-nosession}"
+[ -e "$sentinel" ] && exit 0
+
+# Resolve the lib next to this hook (repo layout), fall back to the
+# installed copy — both paths exist through the link.sh symlinks.
+script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+libsh="${script_dir}/../lib/fast-libs.sh"
+[ -f "$libsh" ] || libsh="${HOME}/.claude/lib/fast-libs.sh"
+[ -f "$libsh" ] || exit 0
+
+libs="$(bash "$libsh" detect "$cwd" 2>/dev/null || true)"
+[ -n "$libs" ] || exit 0
+
+status="$(bash "$libsh" cache-status "$cwd" 2>/dev/null || true)"
+: > "$sentinel" || true
+list="$(printf '%s' "$libs" | tr '\n' ' ' | sed 's/ *$//')"
+
+if [ "$status" = "fresh" ]; then
+  printf '📚 Fast-moving libs in this project (%s) — fresh .ctx7-cache/ present: read the matching cache file before relying on their APIs.\n' "$list"
+else
+  printf '📚 Fast-moving libs in this project (%s) — .ctx7-cache/ %s: consult ctx7 (find-docs skill) before writing code against their APIs. Stable techs need nothing.\n' "$list" "${status:-missing}"
+fi
+
+exit 0