docs: document _find_folder three-level name matching in CLAUDE.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CLAUDE.md

@@ -101,6 +101,11 @@ Pass 2 builds `ok_disk_names` — the set of disk names that already match the s
 - `logs.py` — real-time log viewer fed from the stdout/stderr queue
 - `settings.py` — in-app editor for `config.json` (server URL, paths, credentials)
 
+**`_find_folder` (mods.py) — three-level name matching:** The mods view resolves a mod's local folder by mod name from `comparison.json`, which may differ from the server-canonical folder name used by the fetcher. Lookup order:
+1. Exact: `@{mod_name}`
+2. Case-insensitive: `@CBA_A3` matches `CBA_A3`
+3. Normalized (`_normalize_name`): strips all non-alphanumeric — handles punctuation/spacing differences, e.g. `@US GEAr- Units (IFA3)` matches `US GEAr: Units (IFA3)` (both → `usgearunitsifa3`)
+
 **`selection.json`** — GUI selection state file, tracked in git. Persists which mods/groups are selected between GUI sessions. Written by the GUI; safe to delete (GUI recreates it on next save).
 
 ## Python Version Compatibility

gui/views/mods.py

@@ -7,6 +7,7 @@ from typing import TYPE_CHECKING, Optional
 
 import customtkinter as ctk
 
+from arma_modlist_tools.fetcher import _normalize_name
 from gui._constants import COLOR_OK, COLOR_ERROR, COLOR_WARN, COLOR_RUNNING
 from gui.views.base import BaseView
 
@@ -15,15 +16,26 @@ if TYPE_CHECKING:
 
 
 def _find_folder(group_dir: Path, mod_name: str) -> Optional[Path]:
-    """Return the local mod folder path, or None if not downloaded."""
+    """Return the local mod folder path, or None if not downloaded.
+
+    Matches in priority order:
+    1. Exact folder name ``@{mod_name}``
+    2. Case-insensitive name (handles ``@CBA_A3`` vs ``CBA_A3``)
+    3. Normalized name — strips non-alphanumeric (handles ``@cba_a3`` vs ``CBA A3``)
+    """
     if not group_dir.is_dir():
         return None
     candidate = group_dir / f"@{mod_name}"
     if candidate.is_dir():
         return candidate
-    target = mod_name.lower()
+    target_lower = mod_name.lower()
+    target_norm  = _normalize_name(mod_name)
     for p in group_dir.iterdir():
-        if p.is_dir() and p.name.lstrip("@").lower() == target:
+        if not p.is_dir():
+            continue
+        if p.name.lstrip("@").lower() == target_lower:
+            return p
+        if _normalize_name(p.name) == target_norm:
             return p
     return None