feat(client): fetch the media apps, the player, settings and search on first use

apps.js registers Videos, Music, Photos and every settings pane through
lazy.js; the group page does the same for the video player and the
settings panel, and the shell for the search page. The first download
goes from 49 modules / 386 KB gzip to 37 / 289 KB; opening Music now
fetches music-app.js and media-tiles.js and nothing of Videos.
test_first_load_is_lean holds the eager graph; test_spa_imports checks
that every on-demand load names an export that exists.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 30 insertions, 3 deletions

diff --git a/packages/meshbay-hub/tests/test_spa_imports.py b/packages/meshbay-hub/tests/test_spa_imports.py
index 230f33f..8be70cb 100644
--- a/packages/meshbay-hub/tests/test_spa_imports.py
+++ b/packages/meshbay-hub/tests/test_spa_imports.py
@@ -79,9 +79,36 @@ def test_the_check_can_see_a_real_module():
     finding imports would make the test above pass over an empty set, which
     looks exactly like success.
     """
-    source = (STATIC / "apps.js").read_text(encoding="utf-8")
+    source = (STATIC / "group-page.js").read_text(encoding="utf-8")
     found = IMPORT.findall(source)
     assert len(found) >= 5, (
-        "the import pattern no longer matches apps.js — this test is then "
+        "the import pattern no longer matches group-page.js — this test is then "
         "checking nothing")
-    assert "configurableApps" in _exported(source)
+    assert "GroupPage" in _exported(source)
+
+
+# `lazy(() => import('./x.js'), 'Name')` (lazy.js), and the hand-written form
+# `import('./x.js').then(m => { _Page = m.Name; ...`.
+LAZY = re.compile(r"lazy\(\s*\(\)\s*=>\s*import\('\./([^']+)'\),\s*'(\w+)'")
+THEN = re.compile(r"import\('\./([^']+)'\)\.then\(\s*m\s*=>\s*\{\s*\w+\s*=\s*m\.(\w+)")
+
+
+def test_every_module_loaded_on_demand_exports_what_is_asked_for():
+    """
+    The same fault as above, one step later: a component fetched on demand
+    under a name its module does not export renders a spinner that never
+    ends — no error, since the fetch itself succeeded.
+    """
+    problems, seen = [], 0
+    for path in sorted(STATIC.glob("*.js")):
+        source = path.read_text(encoding="utf-8")
+        for spec, name in LAZY.findall(source) + THEN.findall(source):
+            seen += 1
+            target = STATIC / spec
+            if not target.exists():
+                problems.append(f"{path.name}: loads ./{spec} — no such file")
+            elif name not in _exported(target.read_text(encoding="utf-8")):
+                problems.append(f"{path.name}: loads {{{name}}} from ./{spec}, "
+                                f"which does not export it")
+    assert seen >= 15, f"only {seen} on-demand loads found — is the pattern stale?"
+    assert not problems, "unresolved on-demand loads:\n" + "\n".join(problems)