brief sprint C3.b+c+d+e: share-post Line+Brief async, magic-link / invalid-link banners use Brief styling, .alert-* retired — TDD

Closes the C3 brief sprint. Three event sources (note unlock, share invite, login messages) now route through the Brief slide-down, & the legacy .alert-success/.alert-warning rendering in base.html is retired.

C3.b — share-post async Line + Brief:
- billboard.share_post detects Accept: application/json. JSON path appends a Line (text="Shared with X at <isoformat>", isoformat carries microseconds so two rapid shares of the same email don't collide on Line.unique_together(post,text)), spawns a Brief(kind=SHARE_INVITE) for the sharer, and returns {brief: brief.to_banner_dict() | None, line_text, recipient_display}. Sharer-shares-with-themselves stays a silent no-op (response carries brief: null). Legacy form-submit path preserved for non-AJAX (still redirects + flashes the privacy-safe message — kept for older FTs / no-JS fallback).
- billboard.Brief.to_banner_dict() (moved from dashboard.views helper to a model method) shapes the JSON the banner JS consumes.
- post.html: share form intercepted by JS — fetches POST w. Accept:application/json, then appends `data.line_text` as the next row in #id_post_table, calls Brief.showBanner(data.brief), and (when registered) appends a fresh `<span class="post-recipient">` to the new #id_post_recipients box. No page reload — the alert-success flash is gone.
- 10 new ITs (SharePostAsyncTest + SharePostLegacyRedirectTest) cover the JSON path, line append, brief creation w. SHARE_INVITE kind, registered/unregistered recipient behaviour, sharer-self skip, line dedupe via timestamp, and that the legacy form-submit redirect path still works.
- functional_tests.test_sharing line numbering updated: the share now records its own Line so the alice-reply lands at row 3 instead of 2.

C3.c+d — magic-link confirmation + invalid-link error use Brief banner styling:
- base.html's {% if messages %} block stops rendering .alert-success/.alert-warning divs. Instead each message renders as a transient Brief-styled banner: <div class="note-banner note-banner--message note-banner--{{level_tag}}"> with .note-banner__body / __description carrying the message text and a .btn-cancel NVM that removes the banner via inline onclick. No DB Brief row; no FYI; no square. Same Gaussian-glass look as note-unlock + share-invite Briefs.
- _note.scss adds the note-banner--message variant (full-opacity description) + note-banner--error/--warning border-color override (priRd 0.6) so the invalid-link banner reads as red/abandon.

C3.e — .alert-success/.alert-warning retired in markup; the SCSS class blocks aren't referenced anywhere else in templates so they sit dormant (left in place — base form styling keeps .form-control etc. working; no need to ripple into _base.scss).

Banner JS (note.js / Brief module) was untouched in C3.b+c+d — the Brief.showBanner contract from C3.a already handles all three kinds (NOTE_UNLOCK / USER_POST / SHARE_INVITE) by reading kind off the brief; the message-banner path doesn't go through showBanner because there's no Brief row.

Tests: 218 dashboard+billboard+api ITs + 322 lyric+dashboard+billboard ITs + 2 sharing FTs + 9 my_notes FTs + 1 Jasmine FT all green. Existing lyric.test_views login message-text assertions unchanged (they pull from messages framework — not the rendered HTML — so the markup swap doesn't affect them).

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Sonnet 4.6 <noreply@anthropic.com>

src/apps/billboard/tests/integrated/test_share_post.py

@@ -0,0 +1,125 @@
+"""ITs for share-post async-Brief flow (C3.b).
+
+POST /billboard/post/<uuid>/share-post w. Accept: application/json now:
+  - Adds the recipient to Post.shared_with (if registered, not the sharer)
+  - Appends a Line to the Post recording the share event
+  - Spawns a Brief(kind=SHARE_INVITE) for the sharer that JS slide-downs
+  - Returns JSON {brief: {…}, line_text: "…"}; no redirect, no messages
+
+Legacy form-submit (no Accept: application/json) still redirects + flashes
+the privacy-safe success message — kept for non-AJAX fallback / older FTs.
+"""
+
+from django.test import TestCase
+from django.urls import reverse
+
+from apps.billboard.models import Brief, Line, Post
+from apps.lyric.models import User
+
+
+class SharePostAsyncTest(TestCase):
+    def setUp(self):
+        self.sharer = User.objects.create(email="sharer@test.io")
+        self.client.force_login(self.sharer)
+        self.post = Post.objects.create(owner=self.sharer)
+
+    def _share_async(self, recipient_email):
+        return self.client.post(
+            reverse("billboard:share_post", args=[self.post.id]),
+            data={"recipient": recipient_email},
+            HTTP_ACCEPT="application/json",
+        )
+
+    def test_async_share_returns_brief_payload(self):
+        User.objects.create(email="alice@test.io")
+        response = self._share_async("alice@test.io")
+        self.assertEqual(response.status_code, 200)
+        body = response.json()
+        self.assertIn("brief", body)
+        self.assertIn("line_text", body)
+
+    def test_async_share_appends_line_to_post(self):
+        User.objects.create(email="alice@test.io")
+        self.assertEqual(self.post.lines.count(), 0)
+        self._share_async("alice@test.io")
+        self.assertEqual(self.post.lines.count(), 1)
+        line = self.post.lines.first()
+        self.assertIn("alice@test.io", line.text)
+
+    def test_async_share_creates_share_invite_brief_for_sharer(self):
+        User.objects.create(email="alice@test.io")
+        self._share_async("alice@test.io")
+        brief = Brief.objects.get(owner=self.sharer)
+        self.assertEqual(brief.kind, Brief.KIND_SHARE_INVITE)
+        self.assertEqual(brief.post, self.post)
+        self.assertIsNotNone(brief.line)
+        self.assertTrue(brief.is_unread)
+
+    def test_async_share_adds_registered_recipient_to_shared_with(self):
+        alice = User.objects.create(email="alice@test.io")
+        self._share_async("alice@test.io")
+        self.assertIn(alice, self.post.shared_with.all())
+
+    def test_async_share_unregistered_recipient_still_appends_line_and_brief(self):
+        """Privacy: even if the email isn't registered, the sharer gets the
+        same confirmation Brief + Line. Otherwise the response shape would
+        leak whether an address is on the system."""
+        response = self._share_async("ghost@test.io")
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(self.post.lines.count(), 1)
+        self.assertEqual(Brief.objects.filter(owner=self.sharer).count(), 1)
+
+    def test_async_share_does_not_add_owner_as_recipient(self):
+        """Sharer shares w. their own email — no shared_with add, no Line, no
+        Brief; response carries brief: null so the JS just no-ops."""
+        response = self._share_async("sharer@test.io")
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.json()["brief"], None)
+        self.assertEqual(self.post.lines.count(), 0)
+        self.assertEqual(Brief.objects.filter(owner=self.sharer).count(), 0)
+        self.assertNotIn(self.sharer, self.post.shared_with.all())
+
+    def test_async_share_brief_payload_carries_share_invite_kind(self):
+        User.objects.create(email="alice@test.io")
+        body = self._share_async("alice@test.io").json()
+        self.assertEqual(body["brief"]["kind"], "share_invite")
+        self.assertIn("alice@test.io", body["line_text"])
+
+    def test_async_share_line_text_dedupes_via_timestamp(self):
+        """Two consecutive shares of the same email must not collide on the
+        Line.unique_together(post, text) constraint — the share line should
+        carry a timestamp suffix."""
+        User.objects.create(email="alice@test.io")
+        self._share_async("alice@test.io")
+        # Second share — should append a second distinct Line, not 500.
+        response = self._share_async("alice@test.io")
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(self.post.lines.count(), 2)
+
+
+class SharePostLegacyRedirectTest(TestCase):
+    """Legacy form-submit path (no Accept: application/json) is preserved —
+    redirects + flashes the privacy-safe message + adds shared_with. Existing
+    FTs that submit the share form via Selenium still work."""
+
+    def setUp(self):
+        self.sharer = User.objects.create(email="sharer@test.io")
+        self.client.force_login(self.sharer)
+        self.post = Post.objects.create(owner=self.sharer)
+
+    def test_form_submit_still_redirects(self):
+        User.objects.create(email="alice@test.io")
+        response = self.client.post(
+            reverse("billboard:share_post", args=[self.post.id]),
+            data={"recipient": "alice@test.io"},
+        )
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response["Location"], reverse("billboard:view_post", args=[self.post.id]))
+
+    def test_form_submit_still_adds_shared_with(self):
+        alice = User.objects.create(email="alice@test.io")
+        self.client.post(
+            reverse("billboard:share_post", args=[self.post.id]),
+            data={"recipient": "alice@test.io"},
+        )
+        self.assertIn(alice, self.post.shared_with.all())