feat(#607): rebuild get-shit-done-cc → gsd-core migration (per-package cache + installer auto-cleanup + --dry-run) (#611)

* feat(#607): rebuild get-shit-done-cc → gsd-core migration

Leftover get-shit-done-cc installs poisoned the shared update cache,
causing a permanent false "update available". Rebuild the migration so a
stale old install is both harmless and actively removed.

- Per-package update cache filename (gsd-update-check-<slug>.json) in the
  shared ~/.cache/gsd dir, single-sourced via package-identity; writers
  stamp package_name and readers reject foreign/absent lineage. Multi-
  runtime visibility preserved (same shared dir + filename across runtimes).
- New get-shit-done/bin/lib/legacy-cleanup.cjs seam: detects code-file
  references to the old package + the legacy fixed-name cache across home
  runtime dirs; installer auto-cleans on every install; --dry-run previews
  and mutates nothing. User hooks and dev-preferences are never touched.
- update.md cache-clear globs gsd-update-check*.json across ALL supported
  runtimes (adds cursor/windsurf/augment/trae/qwen/hermes/codebuddy/cline).
- Fix worker MODULE_NOT_FOUND post-install (ship managed-hooks-registry.cjs
  + degrade gracefully) so the per-package cache is always written.
- Diataxis how-to: docs/cleanup-get-shit-done-cc.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* chore(#607): add changeset for PR #611

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(#607): set USERPROFILE alongside HOME in dry-run install test for Windows

os.homedir() reads USERPROFILE on win32, so HOME-only isolation let the
spawned installer scan the real runner home on windows-latest. Set both.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

hooks/gsd-statusline.js

@@ -7,6 +7,7 @@ const fs = require('fs');
 const path = require('path');
 const os = require('os');
 const { isSemverNewer } = require('../get-shit-done/bin/lib/semver-compare.cjs');
+const { PACKAGE_NAME, updateCacheFileName } = require('../get-shit-done/bin/lib/package-identity.cjs');
 
 // --- Config + last-command readers ------------------------------------------
 
@@ -395,32 +396,22 @@ function runStatusline() {
     const gsdStateStr = task ? '' : formatGsdState(readGsdState(dir) || {});
 
     // GSD update available?
-    // Check shared cache first (#1421), fall back to runtime-specific cache for
-    // backward compatibility with older gsd-check-update.js versions.
+    // Read only the per-package shared cache file (#607). The legacy
+    // runtime-specific fallback has been removed — the per-package filename
+    // carries lineage and avoids multi-runtime resolution mismatches (#1421).
     let gsdUpdate = '';
-    const sharedCacheFile = path.join(homeDir, '.cache', 'gsd', 'gsd-update-check.json');
-    const legacyCacheFile = path.join(claudeDir, 'cache', 'gsd-update-check.json');
-    const cacheFile = fs.existsSync(sharedCacheFile) ? sharedCacheFile : legacyCacheFile;
+    const cacheFile = path.join(homeDir, '.cache', 'gsd', updateCacheFileName);
     if (fs.existsSync(cacheFile)) {
       try {
         const cache = JSON.parse(fs.readFileSync(cacheFile, 'utf8'));
-        if (cache.update_available) {
+        const { showUpdate, staleWarning } = evaluateUpdateCache(cache);
+        if (showUpdate) {
           gsdUpdate = '\x1b[33m⬆ /gsd:update\x1b[0m │ ';
         }
-        if (cache.stale_hooks && cache.stale_hooks.length > 0) {
-          // If installed version is ahead of npm latest, this is a dev install.
-          // Running /gsd:update would downgrade — show a contextual warning instead.
-          const isDevInstall = (
-            cache.installed &&
-            cache.latest &&
-            cache.latest !== 'unknown' &&
-            isInstalledAheadOfLatest(cache.installed, cache.latest)
-          );
-          if (isDevInstall) {
-            gsdUpdate += '\x1b[33m⚠ dev install — re-run installer to sync hooks\x1b[0m │ ';
-          } else {
-            gsdUpdate += '\x1b[31m⚠ stale hooks — run /gsd:update\x1b[0m │ ';
-          }
+        if (staleWarning === 'dev') {
+          gsdUpdate += '\x1b[33m⚠ dev install — re-run installer to sync hooks\x1b[0m │ ';
+        } else if (staleWarning === 'stale') {
+          gsdUpdate += '\x1b[31m⚠ stale hooks — run /gsd:update\x1b[0m │ ';
         }
       } catch (e) {}
     }
@@ -507,12 +498,39 @@ function isInstalledAheadOfLatest(installed, latest) {
   return isSemverNewer(installed, latest);
 }
 
+/**
+ * Pure function: evaluate an update-check cache object and return display flags.
+ * Applies lineage guard — if package_name is absent or foreign, treats cache as absent.
+ *
+ * @param {object|null} cache  Parsed cache object, or null.
+ * @returns {{ showUpdate: boolean, staleWarning: 'none'|'dev'|'stale' }}
+ */
+function evaluateUpdateCache(cache) {
+  const none = { showUpdate: false, staleWarning: 'none' };
+  if (!cache) return none;
+  // Lineage guard: package_name must be present and match this package.
+  if (!cache.package_name || cache.package_name !== PACKAGE_NAME) return none;
+  const showUpdate = Boolean(cache.update_available);
+  let staleWarning = 'none';
+  if (cache.stale_hooks && cache.stale_hooks.length > 0) {
+    const isDevInstall = (
+      cache.installed &&
+      cache.latest &&
+      cache.latest !== 'unknown' &&
+      isInstalledAheadOfLatest(cache.installed, cache.latest)
+    );
+    staleWarning = isDevInstall ? 'dev' : 'stale';
+  }
+  return { showUpdate, staleWarning };
+}
+
 // Export helpers for unit tests. Harmless when run as a script.
 module.exports = {
   readGsdState, parseStateMd, formatGsdState,
   readGsdConfig, getConfigValue, readLastSlashCommand,
   composeStatusline,
   isInstalledAheadOfLatest,
+  evaluateUpdateCache,
 };
 
 /**