justfile: git hooks resolve prek through the mise shim

prek bakes the full path of the currently installed version into the hooks it
generates (var/mise/installs/prek/<version>/...). That path stops existing as
soon as the pinned version changes or old versions are pruned, and the hook's
PATH fallback finds no prek either, so every commit fails until the hook is
regenerated by hand. It also means a hook keeps running the version it was
generated with, long after mise.toml has moved on.

Rewriting PREK to mise's shim makes the hook resolve whatever mise.toml pins at
the time it runs. The accompanying MISE_DATA_DIR / MISE_TRUSTED_CONFIG_PATHS
exports keep that resolution inside this project - without them mise falls back
to the global data directory and silently installs a second copy of the tool.

The patch loop now covers every hook file prek generated rather than just
pre-commit, since default_install_hook_types decides which ones exist.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

justfile

@@ -74,13 +74,28 @@ prek-install-git-pre-commit-hook: _ensure_mise_tools_installed
     #!/usr/bin/env sh
     set -eu
     {{ just_executable() }} --justfile "{{ justfile() }}" mise exec -- prek install
-    hook="{{ justfile_directory() }}/.git/hooks/pre-commit"
-    # The installed git hook runs later under Git, outside this just/mise environment.
-    # Injecting PREK_HOME keeps prek's cache under var/prek instead of a global home dir,
-    # which is more predictable and works better in sandboxed tools like Codex/OpenCode.
-    if [ -f "$hook" ] && ! grep -q '^export PREK_HOME=' "$hook"; then
-        sed -i '2iexport PREK_HOME="{{ prek_home }}"' "$hook"
-    fi
+    # The installed git hooks run later under Git, outside this just/mise environment,
+    # so they need to be told how to find their tooling:
+    #
+    # - PREK_HOME keeps prek's cache under var/prek instead of a global home dir.
+    # - MISE_DATA_DIR / MISE_TRUSTED_CONFIG_PATHS make mise resolve against this project's
+    #   own data directory. Without them mise falls back to the global one and silently
+    #   installs a second copy of the tool there.
+    # - prek bakes the full path of the currently installed version into the hook
+    #   (var/mise/installs/prek/<version>/...), which stops working as soon as the pinned
+    #   version changes or old versions are pruned. Pointing at mise's shim instead makes
+    #   the hook resolve whatever mise.toml pins, at the time it runs.
+    #
+    # Which hook files prek installs depends on `default_install_hook_types` in
+    # .pre-commit-config.yaml, so patch every hook file that prek generated.
+    for hook in "{{ justfile_directory() }}"/.git/hooks/*; do
+        [ -f "$hook" ] || continue
+        grep -q 'generated by prek' "$hook" || continue
+        grep -q '^export PREK_HOME=' "$hook" || sed -i '2iexport PREK_HOME="{{ prek_home }}"' "$hook"
+        grep -q '^export MISE_DATA_DIR=' "$hook" || sed -i '3iexport MISE_DATA_DIR="{{ mise_data_dir }}"' "$hook"
+        grep -q '^export MISE_TRUSTED_CONFIG_PATHS=' "$hook" || sed -i '4iexport MISE_TRUSTED_CONFIG_PATHS="{{ mise_trusted_config_paths }}"' "$hook"
+        sed -i 's#^PREK=".*"$#PREK="{{ mise_data_dir }}/shims/prek"#' "$hook"
+    done
 
 # Runs the playbook with --tags=install-all,ensure-matrix-users-created,start and optional arguments
 install-all *extra_args: (run-tags "install-all,ensure-matrix-users-created,start" extra_args)