huge refactor of plugin system

cmdlet/delete_tag.py

@@ -11,6 +11,9 @@ CmdletArg = sh.CmdletArg
 SharedArgs = sh.SharedArgs
 normalize_hash = sh.normalize_hash
 parse_tag_arguments = sh.parse_tag_arguments
+render_tag_value_templates = sh.render_tag_value_templates
+merge_sequences = sh.merge_sequences
+extract_tag_from_result = sh.extract_tag_from_result
 should_show_help = sh.should_show_help
 get_field = sh.get_field
 from SYS.logger import debug, log
@@ -133,6 +136,11 @@ CMDLET = Cmdlet(
     detail=[
         "- Requires a Hydrus file (hash present) or explicit -query override.",
         "- Multiple tags can be comma-separated or space-separated.",
+        "- Use #(namespace) inside a tag value to remove a derived tag, e.g. delete-tag \"title:#(track) - #(series)\".",
+        "- Angle-bracket transforms match add-tag syntax, e.g. delete-tag \"code:e<padding(00,#(episode))>\".",
+        "- Current documented transforms include padding, default, replace, and increment.",
+        "- Template examples assume lowercase tag text; case transforms are intentionally not part of the documented syntax.",
+        "- See docs/tag_template_syntax.md for recipe-style examples and the current shared template syntax.",
     ],
 )
 
@@ -225,7 +233,7 @@ def _run(result: Any, args: Sequence[str], config: Dict[str, Any]) -> int:
         store_name = override_store or get_field(result, "store")
         path = get_field(result, "path") or get_field(result, "target")
         tags = [str(t) for t in grouped_tags if t]
-        return 0 if _process_deletion(tags, file_hash, path, store_name, config) else 1
+        return 0 if _process_deletion(tags, file_hash, path, store_name, config, result=result) else 1
 
     if not tags_arg and not has_piped_tag and not has_piped_tag_list:
         log("Requires at least one tag argument")
@@ -316,7 +324,8 @@ def _run(result: Any, args: Sequence[str], config: Dict[str, Any]) -> int:
                                  item_hash,
                                  item_path,
                                  item_store,
-                                 config):
+                                 config,
+                                 result=item):
                 success_count += 1
 
     if success_count > 0:
@@ -331,6 +340,7 @@ def _process_deletion(
     store_name: str | None,
     config: Dict[str,
                  Any],
+    result: Any = None,
 ) -> bool:
     """Helper to execute the deletion logic for a single target."""
 
@@ -367,12 +377,33 @@ def _process_deletion(
         except Exception:
             return []
 
+    existing_tag_list = merge_sequences(
+        extract_tag_from_result(result),
+        _fetch_existing_tags(),
+        case_sensitive=True,
+    )
+
+    resolved_tags, unresolved_templates = render_tag_value_templates(
+        tags,
+        existing_tags=existing_tag_list,
+        result=result,
+    )
+    if unresolved_templates:
+        log(
+            f"[delete_tag] skipped {len(unresolved_templates)} tag template(s) with unresolved #(namespace) placeholders",
+            file=sys.stderr,
+        )
+
+    tags = list(resolved_tags)
+    if not tags:
+        return False
+
     # Safety: only block if this deletion would remove the final title tag
     title_tags = [
         t for t in tags if isinstance(t, str) and t.lower().startswith("title:")
     ]
     if title_tags:
-        existing_tags = _fetch_existing_tags()
+        existing_tags = existing_tag_list
         current_titles = [
             t for t in existing_tags
             if isinstance(t, str) and t.lower().startswith("title:")