Merge d6cc60c2db into 724867d48d

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/custom-module-manager.js

@@ -424,7 +424,27 @@ class CustomModuleManager {
             stdio: ['ignore', 'pipe', 'pipe'],
           });
         } else {
-          execSync('git reset --hard origin/HEAD', {
+          // Resolve the default branch (origin/HEAD) and fetch it explicitly.
+          // With shallow clones, `origin/HEAD` is stale and `git reset --hard
+          // origin/HEAD` never picks up new commits on the default branch.
+          let defaultBranch = 'main';
+          try {
+            defaultBranch = execSync('git symbolic-ref refs/remotes/origin/HEAD --short', {
+              cwd: repoCacheDir,
+              stdio: 'pipe',
+            })
+              .toString()
+              .trim()
+              .replace('origin/', '');
+          } catch {
+            // Fallback if origin/HEAD is not set
+          }
+          execSync(`git fetch --depth 1 origin ${quoteCustomRef(defaultBranch)}`, {
+            cwd: repoCacheDir,
+            stdio: ['ignore', 'pipe', 'pipe'],
+            env: { ...process.env, GIT_TERMINAL_PROMPT: '0' },
+          });
+          execSync(`git reset --hard origin/${quoteCustomRef(defaultBranch)}`, {
             cwd: repoCacheDir,
             stdio: ['ignore', 'pipe', 'pipe'],
           });

tools/installer/modules/external-manager.js

@@ -524,8 +524,20 @@ class ExternalModuleManager {
       return path.dirname(rootCandidate);
     }
 
-    // Nothing found: return configured path (preserves old behavior for error messaging)
+    // Nothing found: the cloned ref does not contain a recognizable module structure.
-    return path.dirname(configuredPath);
+    // 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}`,
+    );
   }
   cachedModules = null;
 }