Merge 31d6c8357f into c48b6f3069

With shallow clones (--depth 1), `origin/HEAD` becomes stale after the
initial clone. The update path used `git reset --hard origin/HEAD` which
never picked up new commits pushed to the default branch.

Resolve the default branch name via `git symbolic-ref refs/remotes/origin/HEAD`,
then fetch and reset against `origin/<branch>` explicitly. Falls back to
`main` if origin/HEAD is not set.

tools/installer/modules/external-manager.js

@@ -524,20 +524,8 @@ class ExternalModuleManager {
       return path.dirname(rootCandidate);
     }
 
-    // Nothing found: the cloned ref does not contain a recognizable module structure.
-    // This happens when a stable tag predates a module restructure (e.g. the repo
-    // moved files from payload/ to skills/ after the tag was cut). Returning a
-    // non-existent path silently causes a confusing ENOENT deep inside copyModuleWithFiltering;
-    // throw a descriptive error here instead so the user knows what happened and how to recover.
-    const resolution = ExternalModuleManager._resolutions.get(moduleCode);
-    const versionHint = resolution?.version ? `version ${resolution.version}` : 'the cloned version';
-    const channelHint =
-      resolution?.channel === 'stable' ? ` Try reinstalling with \`--next=${moduleCode}\` to use the latest main branch instead.` : '';
-    throw new Error(
-      `Module '${moduleCode}' was downloaded but its module definition was not found. ` +
-        `Expected '${moduleDefinitionPath}' to exist in ${versionHint}, but it is missing. ` +
-        `The repository may have been restructured after this release was tagged.${channelHint}`,
-    );
+    // Nothing found: return configured path (preserves old behavior for error messaging)
+    return path.dirname(configuredPath);
   }
   cachedModules = null;
 }