Add hook system

README.md

@@ -72,3 +72,50 @@ dns-zone-list example.tld
 # Add an A record
 dns-record-add example.tld www 3600 A 192.0.2.1
 ```
+
+## Hooks
+
+Executable scripts placed in the hooks base directory (`hooks_dir`, default
+`<etc_dir>/hooks`) are run around zone and record mutations. The tree narrows
+progressively and every level is optional:
+
+```
+hooks/                          -> every action and phase (zone+record, add+delete, pre+post)
+  zone/                         -> all zone actions/phases
+    add/                        -> zone add, both phases
+      pre/                      -> zone add, pre only
+      post/                     -> zone add, post only
+    delete/{pre,post}/
+  record/
+    add/{pre,post}/
+    delete/{pre,post}/
+```
+
+For a given event `(kind, action, phase)` all matching hooks across every
+existing level along that event's path (`hooks/` → `hooks/<kind>/` →
+`hooks/<kind>/<action>/` → `hooks/<kind>/<action>/<phase>/`) are collected and
+run sorted by filename (run-parts style), so a numeric prefix (e.g. `50-`)
+controls execution order regardless of directory depth. A hook placed shallower
+in the tree fires for more events; distinguish the concrete event via the
+environment variables. Each hook inherits the terminal, so its stdout and stderr
+appear live and in order, and a hook may be interactive: it can print prompts and
+read the user's input from stdin. In batch mode (`-b`) stdin is redirected to
+`/dev/null`, so a hook that reads input gets an immediate EOF instead of blocking
+(hooks that prompt should guard on a tty/EOF).
+Only executable regular files are run; everything else (including the
+`zone`/`record`/`add`/`delete`/`pre`/`post` subdirectories) is skipped, and
+missing directories are no-ops.
+
+Each hook receives context via environment variables:
+
+* Common env: `DNSMGR_KIND` (zone|record), `DNSMGR_ACTION` (add|delete),
+  `DNSMGR_PHASE` (pre|post), `DNSMGR_ZONE` (origin, no trailing dot), `DNSMGR_VIEW`.
+* Record-only env: `DNSMGR_RECORD_NAME`, `DNSMGR_RECORD_TTL`,
+  `DNSMGR_RECORD_TYPE`, `DNSMGR_RECORD_VALUE` (values joined by newlines).
+* `DNSMGR_ZONE_FILE` (zone file path): set only for managed zones and not for zone add pre-hooks and not for zone delete post-hooks.
+
+A `pre` hook exiting non-zero aborts the operation before any change is applied
+(exit code 190); a `post` hook failure only prints an `ERROR:` and continues.
+
+Pass `-n`/`--no-hooks` to `dns-zone-add`, `dns-zone-delete`, `dns-record-add` or
+`dns-record-delete` to skip all hook execution for that run.