admin Posts (NOTE_UNLOCK): readonly input + 'No response needed' placeholder + secUser focus glow + buddy btn suppressed + view POST 403 + Line.admin_solicited listener nukes errant writes; share Lines: drop ts suffix, author = sharer (adman fallback for anon legacy), silent no-op on re-share — TDD

- billboard/0005 adds Line.admin_solicited (BooleanField default False); RunPython backfills existing note_unlock Lines to True. Note.grant_if_new sets admin_solicited=True on its system prose.
  - billboard.models post_save signal: any Line saved on a Post.kind=NOTE_UNLOCK without admin_solicited=True is deleted (defense-in-depth alongside the view guard).
  - billboard.views.view_post hard-rejects POST on NOTE_UNLOCK kind (HTTP 403) — clean view-level contract; the post_save listener is the safety net for ORM/API paths that bypass it.
  - templates/apps/billboard/post.html: NOTE_UNLOCK branch renders the input as readonly w. 'No response needed at this time' placeholder + no method/action; user_post branch keeps the regular composer. Buddy panel include guarded behind `{% if post.kind != 'note_unlock' %}` — friend invites don't apply to admin threads.
  - SCSS: .post-line-form input.form-control[readonly]:focus uses --secUser glow (cooler than the regular --terUser composer focus).
  - share_post: drop the iso-timestamp suffix on Line.text (just 'Shared with {email}'); author = request.user (anon legacy fallback to adman so AnonymousUser doesn't break the FK); re-share of an already-in-shared_with recipient is a silent no-op (no second Line, brief: null in JSON response). Buddy panel JS now reads data-sharer-name from server-rendered display_name so the optimistic _appendLine matches the post-refresh state.
  - new ITs: test_admin_posts (PostRejectsAdminWritesTest, UnsolicitedLineListenerTest, NoteGrantSetsAdminSolicitedTest) — 7 tests; share_post tests rewritten for the new contract (drop ts, author=sharer, silent re-share dedup) — 12 tests; new FT test_admin_post_readonly w. AdminPostInputReadonlyTest + AdminPostHasNoBuddyBtnTest + UserPostInputUnaffectedTest — 4 tests. 827 ITs + 18 buddy/sharing FTs green.

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/apps/billboard/migrations/0005_line_admin_solicited.py

@@ -0,0 +1,34 @@
+# Adds Line.admin_solicited (BooleanField) to discriminate
+# system-authored Lines (Note.grant_if_new) from user writes on
+# NOTE_UNLOCK Posts. The post_save signal nukes any Line on a
+# NOTE_UNLOCK Post that lacks admin_solicited=True — defense-in-depth
+# alongside the view_post POST guard. Backfill: existing NOTE_UNLOCK
+# Lines (the only system-authored kind at this point) get True; all
+# others default False.
+
+from django.db import migrations, models
+
+
+def backfill(apps, schema_editor):
+    Line = apps.get_model("billboard", "Line")
+    Line.objects.filter(post__kind="note_unlock").update(admin_solicited=True)
+
+
+def reverse_noop(apps, schema_editor):
+    pass
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("billboard", "0004_post_title_line_author_created_at"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="line",
+            name="admin_solicited",
+            field=models.BooleanField(default=False),
+        ),
+        migrations.RunPython(backfill, reverse_noop),
+    ]

src/apps/billboard/models.py

@@ -1,6 +1,8 @@
 import uuid
 
 from django.db import models
+from django.db.models.signals import post_save
+from django.dispatch import receiver
 from django.urls import reverse
 from django.utils import timezone
 
@@ -63,6 +65,10 @@ class Line(models.Model):
         related_name="authored_lines",
     )
     created_at = models.DateTimeField(auto_now_add=True)
+    # System-authored Lines on NOTE_UNLOCK Posts must set this True; the
+    # post_save signal below deletes any Line on a NOTE_UNLOCK Post w.o.
+    # this flag (defense-in-depth alongside view_post's POST guard).
+    admin_solicited = models.BooleanField(default=False)
 
     class Meta:
         ordering = ("created_at", "id")
@@ -149,3 +155,18 @@ class Brief(models.Model):
             "square_url": square_url,
             "created_at": self.created_at.isoformat(),
         }
+
+
+# ── Listener: nuke unsolicited Lines on NOTE_UNLOCK Posts ─────────────────
+# Defense-in-depth alongside view_post's POST guard. A Line saved on a
+# NOTE_UNLOCK Post that lacks admin_solicited=True (e.g. a stray ORM-level
+# write or an API path that bypasses the view) gets deleted right after
+# the save. Note.grant_if_new sets admin_solicited=True on its Lines so
+# legitimate system prose survives.
+
+@receiver(post_save, sender=Line)
+def _delete_unsolicited_admin_post_lines(sender, instance, created, **kwargs):
+    if not created:
+        return
+    if instance.post.kind == Post.KIND_NOTE_UNLOCK and not instance.admin_solicited:
+        instance.delete()

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

@@ -0,0 +1,126 @@
+"""ITs for admin-Post (kind=NOTE_UNLOCK) write protection.
+
+Three guards stack:
+  1. post.html input is `readonly` w. "No response needed…" placeholder
+     (FT covers this — `functional_tests/test_admin_post_readonly.py`).
+  2. view_post POST handler hard-rejects writes (HTTP 403). This file's
+     PostRejectsAdminWritesTest.
+  3. post_save signal nukes any Line saved on a NOTE_UNLOCK Post that
+     lacks `admin_solicited=True` — defense-in-depth for paths that
+     bypass the view (raw API, ORM, etc.). UnsolicitedLineListenerTest.
+
+Bug A — May 2026.
+"""
+from django.test import TestCase
+from django.urls import reverse
+
+from apps.billboard.models import Brief, Line, Post
+from apps.drama.models import Note
+from apps.lyric.models import User, get_or_create_adman
+
+
+class PostRejectsAdminWritesTest(TestCase):
+    """POST /billboard/post/<note_unlock>/ → HTTP 403, no Line appended."""
+
+    def setUp(self):
+        self.user = User.objects.create(email="admin-rej@test.io")
+        self.client.force_login(self.user)
+        Note.grant_if_new(self.user, "stargazer")
+        self.admin_post = Post.objects.get(
+            owner=self.user, kind=Post.KIND_NOTE_UNLOCK,
+        )
+        self.line_count_before = Line.objects.filter(post=self.admin_post).count()
+
+    def test_post_to_admin_post_returns_403(self):
+        resp = self.client.post(
+            reverse("billboard:view_post", args=[self.admin_post.id]),
+            data={"text": "errant response"},
+        )
+        self.assertEqual(resp.status_code, 403)
+
+    def test_post_to_admin_post_does_not_append_line(self):
+        self.client.post(
+            reverse("billboard:view_post", args=[self.admin_post.id]),
+            data={"text": "errant response"},
+        )
+        self.assertEqual(
+            Line.objects.filter(post=self.admin_post).count(),
+            self.line_count_before,
+        )
+
+    def test_post_to_user_post_still_succeeds(self):
+        """Regression: kind=USER_POST still accepts compose."""
+        user_post = Post.objects.create(
+            owner=self.user, kind=Post.KIND_USER_POST, title="composing",
+        )
+        Line.objects.create(post=user_post, text="seed", author=self.user)
+        resp = self.client.post(
+            reverse("billboard:view_post", args=[user_post.id]),
+            data={"text": "valid append"},
+        )
+        # 302 redirect on success
+        self.assertEqual(resp.status_code, 302)
+        self.assertTrue(
+            Line.objects.filter(post=user_post, text="valid append").exists(),
+        )
+
+
+class UnsolicitedLineListenerTest(TestCase):
+    """post_save signal deletes any Line saved on a NOTE_UNLOCK Post without
+    `admin_solicited=True`. Note.grant_if_new sets it; everything else
+    defaults to False, so a stray ORM-level write gets nuked."""
+
+    def setUp(self):
+        self.user = User.objects.create(email="listener@test.io")
+        Note.grant_if_new(self.user, "stargazer")
+        self.admin_post = Post.objects.get(
+            owner=self.user, kind=Post.KIND_NOTE_UNLOCK,
+        )
+
+    def test_unsolicited_line_on_note_unlock_post_is_deleted(self):
+        unsolicited = Line.objects.create(
+            post=self.admin_post,
+            text="errant ORM write",
+            author=self.user,
+            # admin_solicited defaults to False
+        )
+        # Signal fires post_save; the Line should be gone.
+        self.assertFalse(
+            Line.objects.filter(pk=unsolicited.pk).exists(),
+            "Unsolicited Line on NOTE_UNLOCK Post must be deleted",
+        )
+
+    def test_admin_solicited_line_on_note_unlock_post_persists(self):
+        """The Note grant Lines are admin_solicited=True — must NOT be nuked."""
+        adman = get_or_create_adman()
+        line = Line.objects.create(
+            post=self.admin_post,
+            text="valid system prose",
+            author=adman,
+            admin_solicited=True,
+        )
+        self.assertTrue(Line.objects.filter(pk=line.pk).exists())
+
+    def test_unsolicited_line_on_user_post_persists(self):
+        """User-typed Lines on user_post posts default to admin_solicited=False
+        and must NOT be nuked — the listener only guards NOTE_UNLOCK."""
+        up = Post.objects.create(
+            owner=self.user, kind=Post.KIND_USER_POST, title="x",
+        )
+        line = Line.objects.create(
+            post=up, text="user-typed line", author=self.user,
+        )
+        self.assertTrue(Line.objects.filter(pk=line.pk).exists())
+
+
+class NoteGrantSetsAdminSolicitedTest(TestCase):
+    """Note.grant_if_new must persist Lines with admin_solicited=True so
+    they survive the listener pass."""
+
+    def test_grant_creates_line_with_admin_solicited_true(self):
+        u = User.objects.create(email="grant@test.io")
+        Note.grant_if_new(u, "stargazer")
+        post = Post.objects.get(owner=u, kind=Post.KIND_NOTE_UNLOCK)
+        # Exactly one Line on a fresh grant
+        line = post.lines.get()
+        self.assertTrue(line.admin_solicited)

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

@@ -85,16 +85,42 @@ class SharePostAsyncTest(TestCase):
         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."""
+    def test_async_reshare_same_recipient_is_silent_noop(self):
+        """Sharing the same recipient twice is a silent no-op — Post.shared_with
+        M2M is idempotent so a second add is meaningless, and we don't want a
+        duplicate Line cluttering the thread. Response is 200 with brief=null."""
         User.objects.create(email="alice@test.io")
         self._share_async("alice@test.io")
-        # Second share — should append a second distinct Line, not 500.
+        self.assertEqual(self.post.lines.count(), 1)
+        before_brief_count = Brief.objects.filter(owner=self.sharer).count()
+
         response = self._share_async("alice@test.io")
+
         self.assertEqual(response.status_code, 200)
-        self.assertEqual(self.post.lines.count(), 2)
+        self.assertEqual(response.json()["brief"], None)
+        # No second Line, no second Brief.
+        self.assertEqual(self.post.lines.count(), 1)
+        self.assertEqual(
+            Brief.objects.filter(owner=self.sharer).count(),
+            before_brief_count,
+        )
+
+    def test_async_share_line_text_drops_timestamp(self):
+        """The share Line's text is plain "Shared with X" — no "at <iso ts>"
+        suffix (timestamp display lives on the per-Line `<time>` element now)."""
+        User.objects.create(email="alice@test.io")
+        self._share_async("alice@test.io")
+        line = self.post.lines.first()
+        self.assertEqual(line.text, "Shared with alice@test.io")
+        self.assertNotIn(" at ", line.text)
+
+    def test_async_share_line_author_is_sharer_not_adman(self):
+        """User-created share Lines attribute to the sharer (the post owner
+        doing the share), not the system adman entity."""
+        User.objects.create(email="alice@test.io")
+        self._share_async("alice@test.io")
+        line = self.post.lines.first()
+        self.assertEqual(line.author, self.sharer)
 
 
 class SharePostLegacyRedirectTest(TestCase):

src/apps/billboard/views.py

@@ -8,7 +8,6 @@ from django.http import HttpResponseForbidden, JsonResponse
 from django.shortcuts import redirect, render
 
 from apps.applets.utils import applet_context, apply_applet_toggle
-from django.utils import timezone
 
 from apps.billboard.forms import ExistingPostLineForm, LineForm
 from apps.billboard.models import Brief, Line, Post
@@ -264,6 +263,13 @@ def view_post(request, post_id):
         if request.user != our_post.owner and request.user not in our_post.shared_with.all():
             return HttpResponseForbidden()
 
+    # Admin-Post (note-unlock thread) hard write-rejection — the per-Line
+    # signal in billboard.models nukes any Line that bypasses this guard,
+    # but at the view level we want a clean 403 so the FT/IT contract is
+    # explicit and the client never sees a silent line vanish.
+    if our_post.kind == Post.KIND_NOTE_UNLOCK and request.method == "POST":
+        return HttpResponseForbidden()
+
     form = ExistingPostLineForm(for_post=our_post)
 
     if request.method == "POST":
@@ -315,30 +321,39 @@ def share_post(request, post_id):
             return JsonResponse({"brief": None, "line_text": ""})
         return redirect(our_post)
 
-    if recipient is not None:
+    # Re-share dedup: if the recipient is already in shared_with (registered
+    # email previously shared), skip the Line + Brief — silent no-op.
+    # `add()` itself is idempotent on M2M, but we want the JSON response to
+    # signal "nothing happened" so the JS can suppress the banner.
+    is_reshare = recipient is not None and recipient in our_post.shared_with.all()
+
+    if recipient is not None and not is_reshare:
         our_post.shared_with.add(recipient)
 
-    # Always append a Line + spawn a Brief for the sharer — privacy: the
-    # response shape mustn't leak whether the email is on the system. Line
-    # text carries an isoformat timestamp w/ microseconds so two rapid
-    # shares of the same email don't collide on the
-    # Line.unique_together(post, text) constraint. System-authored as adman
-    # so the per-line "username" column renders the share announcement.
-    line_text = (
-        f"Shared with {recipient_email} at {timezone.now().isoformat()}"
-    )
-    adman = get_or_create_adman()
-    line = Line.objects.create(post=our_post, text=line_text, author=adman)
-
+    line = None
     brief = None
-    if request.user.is_authenticated:
-        brief = Brief.objects.create(
-            owner=request.user,
-            post=our_post,
-            line=line,
-            kind=Brief.KIND_SHARE_INVITE,
-            title="Invite sent",
+    line_text = ""
+    if not is_reshare:
+        # Plain "Shared with X" — timestamp display lives on the per-Line
+        # `<time>` element, not in the prose. Author = sharer (post owner)
+        # so the per-line "username" column attributes correctly. Anonymous
+        # shares (legacy Percival ch. 19 ownerless-post path) fall back to
+        # adman since AnonymousUser can't be FK'd. Privacy: we still create
+        # the Line + Brief even when the address is unregistered, so the
+        # response doesn't leak membership.
+        line_text = f"Shared with {recipient_email}"
+        author = request.user if request.user.is_authenticated else get_or_create_adman()
+        line = Line.objects.create(
+            post=our_post, text=line_text, author=author,
         )
+        if request.user.is_authenticated:
+            brief = Brief.objects.create(
+                owner=request.user,
+                post=our_post,
+                line=line,
+                kind=Brief.KIND_SHARE_INVITE,
+                title="Invite sent",
+            )
 
     if is_ajax:
         # recipient_display is populated only when the address resolves to a

src/apps/drama/models.py

@@ -315,7 +315,10 @@ class Note(models.Model):
         # super-schizo + super-nomad via the User post_save signal) need a
         # safety net. Production migrations seed it once.
         adman = get_or_create_adman()
-        line = Line.objects.create(post=post, text=line_text, author=adman)
+        line = Line.objects.create(
+            post=post, text=line_text, author=adman,
+            admin_solicited=True,
+        )
         brief = Brief.objects.create(
             owner=user,
             post=post,

src/functional_tests/test_admin_post_readonly.py

@@ -0,0 +1,118 @@
+"""FT spec for admin-Post (kind=NOTE_UNLOCK) readonly input.
+
+Bug A: a Note-unlock Post is system-authored and shouldn't accept user
+responses. The post.html input field gets a "No response needed at this
+time" placeholder + the readonly attribute, AND the server-side view_post
+POST handler hard-rejects writes (defense-in-depth alongside the
+post_save listener that nukes any errant Line that sneaks in).
+
+Run:
+    python src/manage.py test functional_tests.test_admin_post_readonly
+"""
+from django.utils import timezone
+from selenium.webdriver.common.by import By
+from selenium.webdriver.common.keys import Keys
+
+from apps.billboard.models import Line, Post
+from apps.drama.models import Note
+from apps.lyric.models import User
+
+from .base import FunctionalTest
+
+
+class AdminPostInputReadonlyTest(FunctionalTest):
+    """The note-unlock Post's input is readonly + carries a 'No response
+    needed' placeholder. User-Post inputs stay untouched."""
+
+    def setUp(self):
+        super().setUp()
+        self.gamer = User.objects.create(email="reader@test.io")
+        # Note.grant_if_new auto-creates the Notes & recognitions Post.
+        Note.grant_if_new(self.gamer, "stargazer")
+        self.admin_post = Post.objects.get(
+            owner=self.gamer, kind=Post.KIND_NOTE_UNLOCK,
+        )
+        self.create_pre_authenticated_session("reader@test.io")
+
+    def test_admin_post_input_is_readonly(self):
+        self.browser.get(
+            self.live_server_url + f"/billboard/post/{self.admin_post.id}/"
+        )
+        inp = self.wait_for(
+            lambda: self.browser.find_element(By.ID, "id_post_line_text")
+        )
+        self.assertTrue(
+            inp.get_attribute("readonly"),
+            "Admin-Post input should carry readonly attribute",
+        )
+
+    def test_admin_post_input_has_no_response_placeholder(self):
+        self.browser.get(
+            self.live_server_url + f"/billboard/post/{self.admin_post.id}/"
+        )
+        inp = self.wait_for(
+            lambda: self.browser.find_element(By.ID, "id_post_line_text")
+        )
+        self.assertEqual(
+            inp.get_attribute("placeholder"),
+            "No response needed at this time",
+        )
+
+
+class AdminPostHasNoBuddyBtnTest(FunctionalTest):
+    """Admin-Post (note-unlock thread) suppresses #id_buddy_btn — friend
+    invites don't apply to system-authored threads. User-Post still
+    renders the btn (regression coverage in test_buddy_btn.py)."""
+
+    def setUp(self):
+        super().setUp()
+        self.gamer = User.objects.create(email="nobuddy@test.io")
+        Note.grant_if_new(self.gamer, "stargazer")
+        self.admin_post = Post.objects.get(
+            owner=self.gamer, kind=Post.KIND_NOTE_UNLOCK,
+        )
+        self.create_pre_authenticated_session("nobuddy@test.io")
+
+    def test_buddy_btn_absent_on_admin_post(self):
+        self.browser.get(
+            self.live_server_url + f"/billboard/post/{self.admin_post.id}/"
+        )
+        # Wait for page to settle — readonly input is the marker.
+        self.wait_for(
+            lambda: self.browser.find_element(By.ID, "id_post_line_text")
+        )
+        self.assertFalse(
+            self.browser.find_elements(By.ID, "id_buddy_btn"),
+            "Admin-Post must NOT render #id_buddy_btn",
+        )
+
+
+class UserPostInputUnaffectedTest(FunctionalTest):
+    """Regression: user-Post input keeps the regular composer affordances."""
+
+    def setUp(self):
+        super().setUp()
+        self.gamer = User.objects.create(email="composer@test.io")
+        self.user_post = Post.objects.create(
+            owner=self.gamer, kind=Post.KIND_USER_POST, title="hello",
+        )
+        Line.objects.create(
+            post=self.user_post, text="hello", author=self.gamer,
+        )
+        self.create_pre_authenticated_session("composer@test.io")
+
+    def test_user_post_input_is_not_readonly(self):
+        self.browser.get(
+            self.live_server_url + f"/billboard/post/{self.user_post.id}/"
+        )
+        inp = self.wait_for(
+            lambda: self.browser.find_element(By.ID, "id_post_line_text")
+        )
+        self.assertFalse(
+            inp.get_attribute("readonly"),
+            "User-Post input must NOT be readonly",
+        )
+        self.assertEqual(
+            inp.get_attribute("placeholder"),
+            "Enter a post line",
+        )

src/static_src/scss/_billboard.scss

@@ -203,6 +203,14 @@ body.page-billpost {
 
         input.form-control {
             width: 100%;
+
+            // Admin-Post readonly input — no response is invited, so the
+            // focus halo softens to --secUser (cooler than the regular
+            // --terUser glow used on user-Post composers).
+            &[readonly]:focus {
+                border-color: rgba(var(--secUser), 0.6);
+                box-shadow: 0 0 0.75rem rgba(var(--secUser), 0.4);
+            }
         }
     }
 }

src/templates/apps/billboard/_partials/_buddy_panel.html

@@ -1,4 +1,5 @@
 {% load static %}
+{% load lyric_extras %}
 {# ─────────────────────────────────────────────────────────────────────── #}
 {# _buddy_panel.html — bottom-left handshake btn + slide-out recipient    #}
 {# field for the share-post async flow. Mirror of #id_kit_btn (bottom-     #}
@@ -13,7 +14,9 @@
     <i class="fa-solid fa-handshake"></i>
 </button>
 
-<div id="id_buddy_panel" data-share-url="{% url 'billboard:share_post' post.id %}">
+<div id="id_buddy_panel"
+     data-share-url="{% url 'billboard:share_post' post.id %}"
+     data-sharer-name="{% if request.user.is_authenticated %}{{ request.user|display_name }}{% endif %}">
     <input id="id_recipient"
            name="recipient"
            type="email"
@@ -76,15 +79,17 @@
     // OK → POST share-post async; reuses the C3.b response handling so the
     // recipient chip + brief banner + post-line append all light up.
     // Post-May08b layout: #id_post_table is a <ul> of <li class="post-line">
-    // rows; share-invite Lines are adman-authored (system prose, italic).
+    // rows. Author = the sharer (rendered server-side as data-sharer-name on
+    // the panel) so the appended Line matches the post-refresh state, where
+    // the persisted Line.author is request.user.
     function _appendLine(text) {
         var list = document.getElementById('id_post_table');
         if (!list) return;
         var li = document.createElement('li');
-        li.className = 'post-line post-line--system';
+        li.className = 'post-line';
         var author = document.createElement('span');
         author.className = 'post-line-author';
-        author.textContent = 'adman';
+        author.textContent = panel.dataset.sharerName || '';
         var body = document.createElement('span');
         body.className = 'post-line-text';
         body.textContent = text;

src/templates/apps/billboard/post.html

@@ -35,26 +35,46 @@
         <li class="post-line-buffer" aria-hidden="true"></li>
     </ul>
 
-    <form id="id_post_line_form" method="POST" action="{% url 'billboard:view_post' post.id %}" class="post-line-form">
-        {% csrf_token %}
-        <input
-            id="id_post_line_text"
-            name="text"
-            class="form-control{% if form.errors.text %} is-invalid{% endif %}"
-            placeholder="Enter a post line"
-            value="{{ form.text.value|default:'' }}"
-            aria-describedby="id_post_line_feedback"
-            required
-        />
-        {% if form.errors %}
-            <div id="id_post_line_feedback" class="invalid-feedback">
-                {{ form.errors.text.0 }}
-            </div>
-        {% endif %}
-    </form>
+    {# Admin-Post (note-unlock thread) input is read-only: the user can't  #}
+    {# respond, and the placeholder calls that out. View_post hard-rejects #}
+    {# POSTs to NOTE_UNLOCK posts; the post_save Line signal is the safety #}
+    {# net for ORM-level / API writes that bypass the view.               #}
+    {% if post.kind == 'note_unlock' %}
+        <form id="id_post_line_form" class="post-line-form">
+            <input
+                id="id_post_line_text"
+                name="text"
+                class="form-control"
+                placeholder="No response needed at this time"
+                readonly
+            />
+        </form>
+    {% else %}
+        <form id="id_post_line_form" method="POST" action="{% url 'billboard:view_post' post.id %}" class="post-line-form">
+            {% csrf_token %}
+            <input
+                id="id_post_line_text"
+                name="text"
+                class="form-control{% if form.errors.text %} is-invalid{% endif %}"
+                placeholder="Enter a post line"
+                value="{{ form.text.value|default:'' }}"
+                aria-describedby="id_post_line_feedback"
+                required
+            />
+            {% if form.errors %}
+                <div id="id_post_line_feedback" class="invalid-feedback">
+                    {{ form.errors.text.0 }}
+                </div>
+            {% endif %}
+        </form>
+    {% endif %}
 
-    {# Buddy btn (bottom-left) + slide-out recipient field — async share. #}
-    {% include "apps/billboard/_partials/_buddy_panel.html" %}
+    {# Buddy btn (bottom-left) + slide-out recipient field — async share.  #}
+    {# Suppressed on admin Posts (note unlock thread) since friend-invites #}
+    {# don't apply to system-authored threads.                             #}
+    {% if post.kind != 'note_unlock' %}
+        {% include "apps/billboard/_partials/_buddy_panel.html" %}
+    {% endif %}
 </div>
 {% endblock content %}