feat(scribe): snippet management UI + REST routes; embed snippets on create

Step 6 of the Drafter recall milestone (#227): a human-facing surface for
the reusable-code snippets that agents record via MCP, plus the REST API
behind it. Backend embeds snippets inline on create/update so they're
recallable immediately, not only after a restart.

Backend:
- routes/snippets.py: GET/POST /api/snippets, GET/PATCH/DELETE
  /api/snippets/<id>. Share-aware per rule #78 (get_note_for_user +
  can_write_note), writes performed as the owner; list owner-scoped —
  mirrors routes/notes.py. Registered in app.py.
- services/snippets.py: embed on create/update via a _embed_snippet
  fire-and-forget helper, covering BOTH the MCP tool and the REST route
  by construction. A snippet's value is immediate recall, so it can't wait
  for the startup-only backfill (see issue: MCP create path doesn't embed
  inline for notes/tasks generally).
- tests/test_routes_snippets.py: structural registration + handler/service
  contract + PATCH-field ↔ update_snippet-kwarg parity (rule #33).

Frontend (Vue 3 + TS):
- api/snippets.ts: typed client, modeled on api/systems.ts.
- views: SnippetListView (search, skeleton/empty/error states),
  SnippetDetailView (read + copy-to-clipboard, ConfirmDialog delete),
  SnippetEditorView (create/edit all fields, Ctrl/Cmd+S, Esc, autofocus,
  validation). v1 quality per rules #24/#27.
- router: /snippets, /snippets/new, /snippets/:id, /snippets/:id/edit.
- NoteType union widened to include 'snippet'; Snippets nav link added to
  AppHeader (desktop pill bar + mobile menu).
- Design system: Moss --color-action-primary for action buttons, accent
  --color-primary reserved for tags/brand (Hybrid rule); focus rings;
  JetBrains Mono for code/name/signature/location.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pa2EsuB54BuWQ8GfJq9c7t

frontend/src/views/SnippetDetailView.vue

@@ -0,0 +1,316 @@
+<script setup lang="ts">
+import { ref, computed, onMounted } from "vue";
+import { useRoute, useRouter } from "vue-router";
+import { getSnippet, deleteSnippet, type Snippet } from "@/api/snippets";
+import { useToastStore } from "@/stores/toast";
+import ConfirmDialog from "@/components/ConfirmDialog.vue";
+
+const route = useRoute();
+const router = useRouter();
+const toast = useToastStore();
+
+const snippet = ref<Snippet | null>(null);
+const loading = ref(false);
+const error = ref<string | null>(null);
+const showDeleteConfirm = ref(false);
+
+const id = computed(() => Number(route.params.id));
+
+const canWrite = computed(() => {
+  const p = snippet.value?.permission;
+  return p === undefined || p === "owner" || p === "edit" || p === "admin";
+});
+
+const locationParts = computed(() => {
+  const s = snippet.value?.snippet;
+  if (!s) return [];
+  return [s.repo, s.path, s.symbol].filter((p) => p && p.trim());
+});
+
+async function load() {
+  loading.value = true;
+  error.value = null;
+  try {
+    snippet.value = await getSnippet(id.value);
+  } catch (e: unknown) {
+    const status = (e as { status?: number }).status;
+    error.value = status === 404
+      ? "This snippet couldn't be found."
+      : "Couldn't load this snippet.";
+  } finally {
+    loading.value = false;
+  }
+}
+
+onMounted(load);
+
+async function copyCode() {
+  const code = snippet.value?.snippet.code ?? "";
+  try {
+    await navigator.clipboard.writeText(code);
+    toast.show("Code copied");
+  } catch {
+    toast.show("Couldn't copy — select and copy manually", "error");
+  }
+}
+
+async function confirmDelete() {
+  try {
+    await deleteSnippet(id.value);
+    toast.show("Snippet deleted");
+    router.push("/snippets");
+  } catch {
+    toast.show("Failed to delete snippet", "error");
+  } finally {
+    showDeleteConfirm.value = false;
+  }
+}
+</script>
+
+<template>
+  <main class="snippet-detail">
+    <router-link to="/snippets" class="back-link">← Snippets</router-link>
+
+    <div v-if="loading" class="state-msg">Fetching the snippet…</div>
+    <p v-else-if="error" class="error-msg">{{ error }}</p>
+
+    <template v-else-if="snippet">
+      <div class="detail-header">
+        <h1 class="snippet-name">{{ snippet.snippet.name }}</h1>
+        <div class="header-actions" v-if="canWrite">
+          <button class="btn-ghost" @click="router.push(`/snippets/${id}/edit`)">Edit</button>
+          <button class="btn-danger" @click="showDeleteConfirm = true">Delete</button>
+        </div>
+      </div>
+
+      <p v-if="snippet.snippet.when_to_use" class="when-to-use">
+        {{ snippet.snippet.when_to_use }}
+      </p>
+
+      <dl class="meta-grid">
+        <template v-if="snippet.snippet.signature">
+          <dt>Signature</dt>
+          <dd><code>{{ snippet.snippet.signature }}</code></dd>
+        </template>
+        <template v-if="locationParts.length">
+          <dt>Location</dt>
+          <dd class="location">
+            <code v-for="(p, i) in locationParts" :key="i">{{ p }}</code>
+          </dd>
+        </template>
+        <template v-if="snippet.snippet.language">
+          <dt>Language</dt>
+          <dd>{{ snippet.snippet.language }}</dd>
+        </template>
+      </dl>
+
+      <div class="code-block">
+        <div class="code-bar">
+          <span class="code-lang">{{ snippet.snippet.language || "code" }}</span>
+          <button class="btn-ghost btn-copy" @click="copyCode">Copy</button>
+        </div>
+        <pre><code>{{ snippet.snippet.code }}</code></pre>
+      </div>
+
+      <div v-if="snippet.tags.length" class="tag-row">
+        <span v-for="t in snippet.tags" :key="t" class="tag-pill">{{ t }}</span>
+      </div>
+    </template>
+
+    <ConfirmDialog
+      v-if="showDeleteConfirm"
+      title="Delete snippet"
+      :message="`Delete “${snippet?.snippet.name}”? This can be restored from the trash.`"
+      confirmLabel="Delete"
+      danger
+      @confirm="confirmDelete"
+      @cancel="showDeleteConfirm = false"
+    />
+  </main>
+</template>
+
+<style scoped>
+.snippet-detail {
+  max-width: 820px;
+  margin: 2rem auto;
+  padding: 0 var(--page-padding-x);
+  overflow-x: clip;
+}
+
+.back-link {
+  display: inline-block;
+  margin-bottom: 1rem;
+  font-size: 0.85rem;
+  color: var(--color-text-secondary);
+  text-decoration: none;
+}
+.back-link:hover {
+  color: var(--color-primary);
+}
+
+.state-msg {
+  color: var(--color-text-muted);
+  font-size: 0.9rem;
+  margin-top: 1rem;
+}
+.error-msg {
+  color: var(--color-danger);
+  font-size: 0.9rem;
+  margin-top: 1rem;
+}
+
+.detail-header {
+  display: flex;
+  align-items: flex-start;
+  justify-content: space-between;
+  gap: 1rem;
+}
+.snippet-name {
+  margin: 0;
+  font-family: var(--font-mono, ui-monospace, "JetBrains Mono", monospace);
+  font-size: 1.4rem;
+  word-break: break-word;
+}
+.header-actions {
+  display: flex;
+  gap: 0.5rem;
+  flex-shrink: 0;
+}
+
+.btn-ghost {
+  padding: 0.35rem 0.8rem;
+  border: 1px solid var(--color-border);
+  background: transparent;
+  color: var(--color-text);
+  border-radius: var(--radius-sm);
+  cursor: pointer;
+  font-size: 0.85rem;
+  font-family: inherit;
+  transition: border-color 0.15s, color 0.15s;
+}
+.btn-ghost:hover {
+  border-color: var(--color-primary);
+  color: var(--color-primary);
+}
+.btn-danger {
+  padding: 0.35rem 0.8rem;
+  border: none;
+  background: var(--color-action-destructive, #6B2118);
+  color: #fff;
+  border-radius: var(--radius-sm);
+  cursor: pointer;
+  font-size: 0.85rem;
+  font-family: inherit;
+}
+.btn-danger:hover {
+  opacity: 0.9;
+}
+
+.when-to-use {
+  margin: 0.75rem 0 1.25rem;
+  font-size: 1rem;
+  color: var(--color-text-secondary);
+  line-height: 1.55;
+}
+
+.meta-grid {
+  display: grid;
+  grid-template-columns: max-content 1fr;
+  gap: 0.4rem 1rem;
+  margin: 0 0 1.5rem;
+}
+.meta-grid dt {
+  font-size: 0.7rem;
+  text-transform: uppercase;
+  letter-spacing: 0.06em;
+  color: var(--color-text-muted);
+  padding-top: 0.15rem;
+}
+.meta-grid dd {
+  margin: 0;
+  font-size: 0.9rem;
+  color: var(--color-text);
+  min-width: 0;
+}
+.meta-grid code,
+.tag-row + * code {
+  font-family: var(--font-mono, ui-monospace, "JetBrains Mono", monospace);
+  font-size: 0.82rem;
+  background: color-mix(in srgb, var(--color-primary) 12%, transparent);
+  color: var(--color-primary);
+  padding: 0.08rem 0.35rem;
+  border-radius: var(--radius-sm);
+  word-break: break-all;
+}
+.location {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.35rem;
+  align-items: center;
+}
+
+.code-block {
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-md);
+  overflow: hidden;
+  background: var(--color-bg);
+}
+.code-bar {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 0.4rem 0.5rem 0.4rem 0.85rem;
+  border-bottom: 1px solid var(--color-border);
+  background: var(--color-bg-secondary);
+}
+.code-lang {
+  font-size: 0.72rem;
+  text-transform: uppercase;
+  letter-spacing: 0.06em;
+  color: var(--color-text-muted);
+}
+.btn-copy {
+  padding: 0.2rem 0.65rem;
+  font-size: 0.78rem;
+}
+.code-block pre {
+  margin: 0;
+  padding: 1rem;
+  overflow-x: auto;
+}
+.code-block code {
+  font-family: var(--font-mono, ui-monospace, "JetBrains Mono", monospace);
+  font-size: 0.85rem;
+  line-height: 1.6;
+  color: var(--color-text);
+  white-space: pre;
+}
+
+.tag-row {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.4rem;
+  margin-top: 1.25rem;
+}
+.tag-pill {
+  font-size: 0.72rem;
+  padding: 0.15rem 0.5rem;
+  border-radius: 999px;
+  background: var(--color-bg-secondary);
+  color: var(--color-text-secondary);
+  border: 1px solid var(--color-border);
+}
+
+@media (max-width: 600px) {
+  .detail-header {
+    flex-direction: column;
+  }
+  .meta-grid {
+    grid-template-columns: 1fr;
+    gap: 0.15rem 0;
+  }
+  .meta-grid dd {
+    margin-bottom: 0.5rem;
+  }
+}
+</style>