diff --git a/frontend/src/components/rules/ProjectRulesTab.vue b/frontend/src/components/rules/ProjectRulesTab.vue
new file mode 100644
index 0000000..955b58c
--- /dev/null
+++ b/frontend/src/components/rules/ProjectRulesTab.vue
@@ -0,0 +1,211 @@
+<script setup lang="ts">
+import { ref, onMounted, watch } from "vue";
+import { useRouter } from "vue-router";
+import {
+  getProjectApplicableRules, subscribeProject, unsubscribeProject,
+  listRulebooks, getRule,
+} from "@/api/rulebooks";
+import type { ApplicableRules, Rulebook } from "@/api/rulebooks";
+
+const props = defineProps<{ projectId: number }>();
+const router = useRouter();
+const applicable = ref<ApplicableRules | null>(null);
+const allRulebooks = ref<Rulebook[]>([]);
+const showPicker = ref(false);
+const expandedRuleIds = ref<Set<number>>(new Set());
+
+const ruleDetails = ref<Record<number, { why: string; how_to_apply: string }>>({});
+
+async function load() {
+  applicable.value = await getProjectApplicableRules(props.projectId);
+}
+
+async function loadAllRulebooks() {
+  allRulebooks.value = await listRulebooks();
+}
+
+async function subscribe(rulebookId: number) {
+  await subscribeProject(props.projectId, rulebookId);
+  showPicker.value = false;
+  await load();
+}
+
+async function unsubscribe(rulebookId: number) {
+  if (!confirm("Unsubscribe from this rulebook for this project?")) return;
+  await unsubscribeProject(props.projectId, rulebookId);
+  await load();
+}
+
+async function toggleRuleExpand(ruleId: number) {
+  if (expandedRuleIds.value.has(ruleId)) {
+    expandedRuleIds.value.delete(ruleId);
+  } else {
+    expandedRuleIds.value.add(ruleId);
+    if (!ruleDetails.value[ruleId]) {
+      const rule = await getRule(ruleId);
+      ruleDetails.value[ruleId] = {
+        why: rule.why || "",
+        how_to_apply: rule.how_to_apply || "",
+      };
+    }
+  }
+  // trigger reactivity on Set mutation
+  expandedRuleIds.value = new Set(expandedRuleIds.value);
+}
+
+function openInRulesView(rulebookId: number, ruleId?: number) {
+  const query: Record<string, string> = { rb: String(rulebookId) };
+  if (ruleId) query.rule = String(ruleId);
+  router.push({ path: "/rules", query });
+}
+
+function groupByRulebookAndTopic(rules: ApplicableRules["rules"]) {
+  const grouped: Record<string, Record<string, ApplicableRules["rules"]>> = {};
+  for (const r of rules) {
+    if (!grouped[r.rulebook_title]) grouped[r.rulebook_title] = {};
+    if (!grouped[r.rulebook_title][r.topic_title]) grouped[r.rulebook_title][r.topic_title] = [];
+    grouped[r.rulebook_title][r.topic_title].push(r);
+  }
+  return grouped;
+}
+
+function rulebookIdForTitle(title: string): number | undefined {
+  return applicable.value?.subscribed_rulebooks.find((rb) => rb.title === title)?.id;
+}
+
+onMounted(async () => {
+  await load();
+  await loadAllRulebooks();
+});
+
+watch(() => props.projectId, load);
+</script>
+
+<template>
+  <div class="rules-tab" v-if="applicable">
+    <section class="subscribed">
+      <h3>Subscribed rulebooks</h3>
+      <div class="chips">
+        <span
+          v-for="rb in applicable.subscribed_rulebooks"
+          :key="rb.id"
+          class="chip"
+        >
+          <a @click="openInRulesView(rb.id)">{{ rb.title }}</a>
+          <button class="chip-remove" @click="unsubscribe(rb.id)" aria-label="Unsubscribe">×</button>
+        </span>
+        <button v-if="!showPicker" class="add" @click="showPicker = true">+ Subscribe</button>
+        <select
+          v-else
+          @change="subscribe(Number(($event.target as HTMLSelectElement).value))"
+        >
+          <option value="">Choose a rulebook…</option>
+          <option
+            v-for="rb in allRulebooks.filter((rb) => !applicable!.subscribed_rulebooks.some((s) => s.id === rb.id))"
+            :key="rb.id"
+            :value="rb.id"
+          >
+            {{ rb.title }}
+          </option>
+        </select>
+      </div>
+    </section>
+
+    <section class="applicable">
+      <h3>Applicable rules</h3>
+      <p v-if="applicable.rules.length === 0" class="empty">
+        No rules yet — subscribe to a rulebook above, or create one at
+        <a @click="router.push('/rules')">Rulebooks</a>.
+      </p>
+      <div
+        v-for="(topics, rbTitle) in groupByRulebookAndTopic(applicable.rules)"
+        :key="rbTitle"
+        class="rb-group"
+      >
+        <h4>{{ rbTitle }}</h4>
+        <div v-for="(rules, topicTitle) in topics" :key="topicTitle" class="topic-group">
+          <h5>{{ topicTitle }}</h5>
+          <ul>
+            <li v-for="r in rules" :key="r.id" class="rule">
+              <div class="rule-head" @click="toggleRuleExpand(r.id)">
+                <span class="rule-title">{{ r.title }}</span>
+                <span class="rule-statement">{{ r.statement }}</span>
+              </div>
+              <div v-if="expandedRuleIds.has(r.id) && ruleDetails[r.id]" class="rule-detail">
+                <div v-if="ruleDetails[r.id].why">
+                  <strong>Why:</strong> {{ ruleDetails[r.id].why }}
+                </div>
+                <div v-if="ruleDetails[r.id].how_to_apply">
+                  <strong>How to apply:</strong> {{ ruleDetails[r.id].how_to_apply }}
+                </div>
+                <button
+                  class="edit-link"
+                  @click="rulebookIdForTitle(String(rbTitle)) && openInRulesView(rulebookIdForTitle(String(rbTitle))!, r.id)"
+                >
+                  Edit in Rulebook →
+                </button>
+              </div>
+            </li>
+          </ul>
+        </div>
+      </div>
+      <p v-if="applicable.truncated" class="truncated">
+        Truncated at 50 rules — there are more applicable rules.
+      </p>
+    </section>
+  </div>
+</template>
+
+<style scoped>
+.rules-tab { padding: 1rem; }
+h3 {
+  font-size: 0.9em; opacity: 0.7; text-transform: uppercase; letter-spacing: 0.05em;
+  margin-top: 0;
+}
+.chips { display: flex; gap: 0.5rem; flex-wrap: wrap; align-items: center; }
+.chip {
+  display: inline-flex; align-items: center; gap: 0.25rem;
+  background: var(--color-primary-bg, rgba(99,102,241,0.15));
+  padding: 0.25rem 0.5rem; border-radius: 999px;
+}
+.chip a { cursor: pointer; }
+.chip-remove { background: none; border: none; cursor: pointer; opacity: 0.5; font-size: 1.1em; }
+.chip-remove:hover { opacity: 1; }
+.add {
+  background: none;
+  border: 1px dashed var(--color-border, #2a2a2e);
+  padding: 0.25rem 0.75rem; border-radius: 999px; cursor: pointer;
+  color: inherit;
+}
+select {
+  background: var(--color-bg, #111113); color: inherit;
+  border: 1px solid var(--color-border, #2a2a2e); border-radius: 6px;
+  padding: 0.25rem 0.5rem;
+}
+.applicable { margin-top: 2rem; }
+.rb-group { margin-bottom: 1.5rem; }
+.rb-group h4 { font-family: Fraunces, serif; font-style: italic; margin-bottom: 0.5rem; }
+.topic-group h5 {
+  font-size: 0.85em; opacity: 0.7; text-transform: uppercase; letter-spacing: 0.05em;
+  margin-top: 0.75rem;
+}
+ul { list-style: none; padding: 0; margin: 0; }
+.rule {
+  border-left: 2px solid var(--color-primary, #6366f1);
+  padding-left: 0.75rem; margin: 0.5rem 0;
+}
+.rule-head { cursor: pointer; }
+.rule-title { font-weight: 500; }
+.rule-statement { display: block; opacity: 0.85; margin-top: 0.25rem; }
+.rule-detail {
+  margin-top: 0.5rem; padding: 0.5rem;
+  background: var(--color-bg, #111113); border-radius: 6px;
+}
+.rule-detail > div { margin-bottom: 0.5rem; }
+.edit-link {
+  background: none; border: none; cursor: pointer;
+  color: var(--color-primary, #6366f1); padding: 0.5rem 0 0 0;
+}
+.empty, .truncated { opacity: 0.7; font-style: italic; }
+.empty a { cursor: pointer; text-decoration: underline; }
+</style>
diff --git a/frontend/src/views/ProjectView.vue b/frontend/src/views/ProjectView.vue
index 9b83782..f252429 100644
--- a/frontend/src/views/ProjectView.vue
+++ b/frontend/src/views/ProjectView.vue
@@ -5,6 +5,7 @@ import { apiGet, apiPatch, apiDelete, apiPost } from "@/api/client";
 import { useToastStore } from "@/stores/toast";
 import { relativeTime } from "@/composables/useRelativeTime";
 import ShareDialog from "@/components/ShareDialog.vue";
+import ProjectRulesTab from "@/components/rules/ProjectRulesTab.vue";
 import {
   LayoutGrid,
   Clock,
@@ -67,7 +68,7 @@ const loading = ref(false);
 const saving = ref(false);
 const error = ref<string | null>(null);
 
-const activeTab = ref<"tasks" | "notes">("tasks");
+const activeTab = ref<"tasks" | "notes" | "rules">("tasks");
 
 const tasks = ref<NoteItem[]>([]);
 const notes = ref<NoteItem[]>([]);
@@ -436,6 +437,9 @@ async function confirmDelete() {
               Notes
               <span v-if="project.summary" class="tab-count">{{ project.summary.note_count }}</span>
             </button>
+            <button :class="['tab-btn', { active: activeTab === 'rules' }]" @click="activeTab = 'rules'">
+              Rules
+            </button>
           </div>
 
           <!-- Tasks tab — milestone-grouped kanban -->
@@ -616,6 +620,9 @@ async function confirmDelete() {
               <p v-if="!notes.length" class="empty-msg">No notes in this project.</p>
             </template>
           </div>
+
+          <!-- Rules tab -->
+          <ProjectRulesTab v-if="activeTab === 'rules'" :project-id="projectId" />
         </div>
       </div>
     </template>