fix: lazy delivery survives flaky networks and stale caches (#353)

Network failure of the editor runtime is no longer terminal: the loader
re-arms to idle and the next explicit press starts a fresh cycle, while a
fingerprint mismatch on either attempt stays terminal. The toast now says
what actually helps — retry advice for the network, refresh advice for a
foreign build — via one shared lazyLoadFailureMessage helper (new i18n key
editor.retry_advice in en/ru/de).

The field smoke caught a second, deeper bug on the way: Chromium records a
FAILED module in the page module map permanently, so retrying the same URL
(even the cache-busted one) never touched the network again. Every retry
now carries a per-cycle nonce and becomes a genuinely new module request.

A proxy-cached stale entry no longer kills the card silently: the entry
facade is rewritten at build time from a static re-export into a top-level
`try{await import(...)}catch{...}` — importers keep the happy-path
guarantee (await import(entry) still resolves only after
customElements.define), and the catch defines a fallback element with a
localized "reload the page" panel. Content-hashed chunks are served with
`public, max-age=31536000, immutable`, and verifyBundleTree now fails on
orphan chunks that the manifest does not name.

Proofs: loader units for re-arm/terminality/toast wording + an AST check
that both loaders forward the terminality flag; smoke_entry_stale (en/ru)
against a tree without the main chunk; smoke_lazy_editor_chunk extended —
second press after network failure now really opens the editor; pytest for
the immutable header; orphan-tree unit; five new registry mutants.
TESTING.md budget line updated to the #352 ceiling alongside.

Issue: #353
User-Visible: yes

scripts/mutation-gate.mjs

@@ -634,6 +634,64 @@ const MUTANT_DEFINITIONS = [
       replace: '    // mutant: pointer capture removed\n    const plan = resolution.plan;',
     }],
   },
+  {
+    id: 'lazy-loader-network-failure-terminal',
+    guard: 'node --test --test-name-pattern="#353 AC1" test/editor-runtime-loader.test.mjs',
+    because: 'a transient network failure must re-arm the loader for the next explicit press — '
+      + 'a terminal state blocks the editor until a page refresh (#353 К1)',
+    patches: [{
+      file: 'src/editor-runtime-loader.ts',
+      find: "    this._setState(sawMismatch ? 'failed' : 'idle');",
+      replace: "    this._setState('failed');",
+    }],
+  },
+  {
+    id: 'lazy-loader-terminality-hardcoded',
+    guard: 'node --test --test-name-pattern="#353" test/editor-runtime-loader.test.mjs',
+    because: 'a hardcoded terminal flag shows the wrong advice — the network toast must invite '
+      + 'another press, the mismatch toast must demand a refresh (#353 К2/AC5)',
+    patches: [{
+      file: 'src/editor-runtime-loader.ts',
+      find: '    this.options.failed?.(lastError, { terminal: sawMismatch });',
+      replace: '    this.options.failed?.(lastError, { terminal: true });',
+    }],
+  },
+  {
+    id: 'lazy-chunk-cache-control-reverted',
+    guard: 'node scripts/backend-test-guard.mjs hashed_chunks_are_immutably_cacheable '
+      + 'tests_backend/test_frontend_assets.py',
+    because: 'content-hashed chunk bodies never change under their URL — reverting to no-cache '
+      + 'reopens the stale-proxy window and refetches on every editor entry (#353 К4)',
+    patches: [{
+      file: 'custom_components/houseplan/frontend_asset_manifest.py',
+      find: 'ASSET_CACHE_CONTROL = "public, max-age=31536000, immutable"',
+      replace: 'ASSET_CACHE_CONTROL = "no-cache"',
+    }],
+  },
+  {
+    id: 'bundle-tree-orphans-ignored',
+    guard: 'node --test --test-name-pattern="#353 AC4" test/bundle-assets.test.mjs',
+    because: 'an unlisted chunk on disk rides into the release zip and masks sync bugs — '
+      + 'the tree check must fail loudly on orphans (#353 К5)',
+    patches: [{
+      file: 'scripts/bundle-tree.mjs',
+      find: "      if (name.endsWith('.js') && !listed.has(`houseplan-assets/${name}`)) {\n"
+        + '        throw new Error(`orphan bundle asset: houseplan-assets/${name}`);\n'
+        + '      }',
+      replace: "      void name; void listed;",
+    }],
+  },
+  {
+    id: 'entry-fallback-rewrite-skipped',
+    guard: 'node demo/smoke_entry_stale.mjs',
+    because: 'without the rewrite the entry keeps a STATIC re-export: after an update a cached '
+      + 'entry aborts before any code runs and the card dies silently (#353 К3)',
+    patches: [{
+      file: 'scripts/bundle-manifest.mjs',
+      find: '      entry.code = entry.code.replace(pattern, fallback);',
+      replace: '      void fallback;',
+    }],
+  },
   {
     id: 'junction-limit-key-precision-lost',
     guard: 'npx tsc -p tsconfig.test.json && node scripts/fix-test-build.mjs '