docs(skill): consolidate the writing rules and ship a checker for them

.githooks/commit-msg

@@ -26,3 +26,12 @@ if git stripspace --strip-comments <"${msg_file}" | grep -qiE 'bump version'; th
         echo "  (Not blocking this commit; the release build enforces it at tag time.)" >&2
     fi
 fi
+
+# The writing standard covers a commit message like any other artifact, and the pre-commit hook
+# beside this one reads only the staged files. Reports and never blocks, like the check above.
+prose_check="${repo_root}/src/usr/share/ai-tools/skills/ai-tools-technical-docs/prose-check.py"
+if command -v python3 >/dev/null 2>&1 && [[ -r "${prose_check}" ]]; then
+    if ! python3 "${prose_check}" --message "${msg_file}" >&2; then
+        echo "  (not blocking this commit)" >&2
+    fi
+fi

.githooks/pre-commit

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: AGPL-3.0-only
+# pre-commit hook: report the prose figures the ai-tools-technical-docs skill rules out, in the
+# lines this commit ADDS. Reuses the checker the skill ships (prose-check.py beside its
+# SKILL.md), so the hook and a full pass apply one set of patterns.
+#
+# Never blocks, matching the commit-msg reminder beside it: the default checks report correct
+# prose occasionally, and a hook that refuses a commit over a style call is a hook developers
+# turn off. It reports, the author decides.
+#
+# Only the added lines are read, so the ~650 findings already in the tree stay out of every
+# commit until a sweep addresses them.
+#
+# Not installed automatically -- enable once per clone with `make -C packaging hooks`
+# (sets core.hooksPath to .githooks).
+set -euo pipefail
+
+command -v python3 >/dev/null 2>&1 || exit 0
+repo_root="$(git rev-parse --show-toplevel)"
+checker="${repo_root}/src/usr/share/ai-tools/skills/ai-tools-technical-docs/prose-check.py"
+[[ -r "${checker}" ]] || exit 0
+
+if ! python3 "${checker}" --staged; then
+    echo "  (not blocking this commit)" >&2
+fi
+exit 0

CONTRIBUTING.md

@@ -28,10 +28,12 @@ See the root `README.md`'s manual install steps if you're working without the RP
 
 Optional, recommended for regular contributors:
 
-    make -C packaging hooks          # enable the local git hooks (a non-blocking changelog reminder)
+    make -C packaging hooks          # enable the local git hooks (non-blocking reminders)
 
 A per-clone developer opt-in: it sets `core.hooksPath` to `.githooks` and quiets git's
-ignored-hook advice for sandbox-account commits. None of this ships in the RPM — the
+ignored-hook advice for sandbox-account commits. Two hooks come with it, and neither blocks a
+commit: a `commit-msg` changelog reminder, and a `pre-commit` prose report over the lines the
+commit adds (`prose-check.py`, shipped with the `ai-tools-technical-docs` skill). None of this ships in the RPM — the
 package builds only from `src/`, `docs/`, the spec, and the compiled policy.
 
 ## Running the tests

packaging/Makefile

@@ -88,8 +88,10 @@ check-version:
 changelog:
 	@bash $(CURDIR)/changelog-draft.sh
 
-# Opt in (once per clone) to the local git hooks in .githooks -- currently a non-blocking
-# commit-msg reminder to complete the %changelog on a "bump version" commit. Also silence
+# Opt in (once per clone) to the local git hooks in .githooks -- a non-blocking commit-msg
+# reminder to complete the %changelog on a "bump version" commit, and a non-blocking pre-commit
+# report of the prose figures the ai-tools-technical-docs skill rules out in the lines a commit
+# adds. Also silence
 # git's ignored-hook advice: the sandbox account commits under the SELinux ai_tools_t domain,
 # which has no execute on the project-tree ai_tools_project_t label, so git skips the hook and
 # nags about it on every agent commit. That skip is the confinement working (the operator, who