Add clickable tag badges to plan cards and header

db/seeds.rb

@@ -83,6 +83,41 @@
 # Backfill any plans without a plan type
 CoPlan::Plan.where(plan_type_id: nil).update_all(plan_type_id: general.id)
 
+puts "Seeding tags on plans..."
+CoPlan::Plan.includes(:tags, :plan_type).find_each do |p|
+  if p.tags.empty? && p.plan_type&.default_tags&.any?
+    p.tag_names = p.plan_type.default_tags
+  end
+end
+
+# Add some demo plans with tags for local development
+if CoPlan::Plan.count < 3
+  rfc_type = CoPlan::PlanType.find_by(name: "RFC")
+  design_type = CoPlan::PlanType.find_by(name: "Design Doc")
+
+  api_plan = CoPlan::Plans::Create.call(
+    title: "API Rate Limiting Strategy",
+    content: "# API Rate Limiting Strategy\n\n## Problem\n\nOur API endpoints have no rate limiting, leading to occasional abuse.\n\n## Proposal\n\nImplement token-bucket rate limiting at the gateway level.\n\n## Alternatives Considered\n\n- Per-IP limiting\n- API key quotas\n",
+    user: hampton,
+    plan_type_id: rfc_type&.id
+  )
+  api_plan.update!(status: "considering")
+  api_plan.tag_names = ["api", "infrastructure", "security"]
+
+  auth_plan = CoPlan::Plans::Create.call(
+    title: "Authentication System Redesign",
+    content: "# Authentication System Redesign\n\n## Goals\n\n- Migrate from session-based to token-based auth\n- Support SSO providers\n- Improve security posture\n\n## Architecture\n\nOIDC-based flow with JWT access tokens.\n",
+    user: hampton,
+    plan_type_id: design_type&.id
+  )
+  auth_plan.update!(status: "developing")
+  auth_plan.tag_names = ["security", "infrastructure", "design"]
+end
+
+# Tag the original Q3 roadmap if it has no tags
+q3 = CoPlan::Plan.find_by(title: "Q3 Product Roadmap")
+q3.tag_names = ["roadmap", "product"] if q3 && q3.tags.empty?
+
 puts "Seeding automated plan reviewers..."
 CoPlan::AutomatedPlanReviewer.create_defaults
 

engine/app/assets/stylesheets/coplan/application.css

@@ -374,6 +374,10 @@ img, svg {
 .badge--resolved    { background: #d1fae5; color: var(--color-status-live); }
 .badge--agent       { background: var(--color-agent-bg); color: var(--color-agent); font-size: 0.65rem; padding: 1px 6px; vertical-align: middle; }
 .badge--type        { background: #f0fdf4; color: #166534; }
+.badge--tag         { background: #f3f4f6; color: #374151; text-decoration: none; font-size: 0.7rem; text-transform: none; letter-spacing: normal; }
+.badge--tag:hover   { background: #e5e7eb; color: #111827; }
+.badge--tag-active  { background: #374151; color: #fff; }
+.badge--tag-active:hover { background: #1f2937; color: #fff; }
 
 /* Forms */
 .form-group {
@@ -525,10 +529,39 @@ img, svg {
   color: var(--color-primary);
 }
 
+.plans-list__tags {
+  display: flex;
+  flex-wrap: wrap;
+  gap: var(--space-xs);
+  margin-top: var(--space-xs);
+}
+
 .plans-list__meta {
   margin-top: var(--space-xs);
 }
 
+.active-filter {
+  display: flex;
+  align-items: center;
+  gap: var(--space-sm);
+  padding: var(--space-sm) var(--space-md);
+  background: #f9fafb;
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius);
+  font-size: var(--text-sm);
+  margin-bottom: var(--space-md);
+}
+
+.active-filter__clear {
+  color: var(--color-text-muted);
+  text-decoration: none;
+  font-size: var(--text-sm);
+}
+
+.active-filter__clear:hover {
+  color: var(--color-text);
+}
+
 /* Plan form */
 .plan-form__actions {
   display: flex;

engine/app/controllers/coplan/plans_controller.rb

@@ -3,10 +3,11 @@ class PlansController < ApplicationController
     before_action :set_plan, only: [:show, :edit, :update, :update_status]
 
     def index
-      @plans = Plan.includes(:plan_type).order(updated_at: :desc)
+      @plans = Plan.includes(:plan_type, :tags).order(updated_at: :desc)
       @plans = @plans.where(status: params[:status]) if params[:status].present?
       @plans = @plans.where(created_by_user: current_user) if params[:scope] == "mine"
       @plans = @plans.where(plan_type_id: params[:plan_type]) if params[:plan_type].present?
+      @plans = @plans.with_tag(params[:tag]) if params[:tag].present?
 
       @plan_types = PlanType.order(:name)
 

engine/app/models/coplan/plan.rb

@@ -21,6 +21,8 @@ class Plan < ApplicationRecord
     validates :title, presence: true
     validates :status, presence: true, inclusion: { in: STATUSES }
 
+    scope :with_tag, ->(name) { joins(:tags).where(coplan_tags: { name: name }) }
+
     def self.ransackable_attributes(auth_object = nil)
       %w[id title status plan_type_id created_by_user_id current_plan_version_id current_revision created_at updated_at]
     end

engine/app/views/coplan/plans/_header.html.erb

@@ -6,6 +6,9 @@
       <% if plan.plan_type %>
         · <span class="badge badge--type"><%= plan.plan_type.name %></span>
       <% end %>
+      <% plan.tags.each do |tag| %>
+        <%= link_to tag.name, plans_path(tag: tag.name), class: "badge badge--tag" %>
+      <% end %>
     </div>
   </div>
   <div class="page-header__actions">

engine/app/views/coplan/plans/index.html.erb

@@ -3,26 +3,33 @@
 </div>
 
 <div class="status-filters">
-  <%= link_to "All Plans", plans_path(params.permit(:status)), class: "status-filter #{'status-filter--active' if params[:scope].blank?}" %>
-  <%= link_to "My Plans", plans_path(params.permit(:status).merge(scope: "mine")), class: "status-filter #{'status-filter--active' if params[:scope] == 'mine'}" %>
+  <%= link_to "All Plans", plans_path(params.permit(:status, :tag)), class: "status-filter #{'status-filter--active' if params[:scope].blank?}" %>
+  <%= link_to "My Plans", plans_path(params.permit(:status, :tag).merge(scope: "mine")), class: "status-filter #{'status-filter--active' if params[:scope] == 'mine'}" %>
 </div>
 
 <div class="status-filters">
-  <%= link_to "All", plans_path(params.permit(:scope, :plan_type)), class: "status-filter #{'status-filter--active' if params[:status].blank?}" %>
+  <%= link_to "All", plans_path(params.permit(:scope, :plan_type, :tag)), class: "status-filter #{'status-filter--active' if params[:status].blank?}" %>
   <% CoPlan::Plan::STATUSES.each do |status| %>
-    <%= link_to status.titleize, plans_path(params.permit(:scope, :plan_type).merge(status: status)), class: "status-filter status-filter--#{status} #{'status-filter--active' if params[:status] == status}" %>
+    <%= link_to status.titleize, plans_path(params.permit(:scope, :plan_type, :tag).merge(status: status)), class: "status-filter status-filter--#{status} #{'status-filter--active' if params[:status] == status}" %>
   <% end %>
 </div>
 
 <% if @plan_types.any? %>
   <div class="status-filters">
-    <%= link_to "All Types", plans_path(params.permit(:scope, :status)), class: "status-filter #{'status-filter--active' if params[:plan_type].blank?}" %>
+    <%= link_to "All Types", plans_path(params.permit(:scope, :status, :tag)), class: "status-filter #{'status-filter--active' if params[:plan_type].blank?}" %>
     <% @plan_types.each do |pt| %>
-      <%= link_to pt.name, plans_path(params.permit(:scope, :status).merge(plan_type: pt.id)), class: "status-filter #{'status-filter--active' if params[:plan_type] == pt.id}" %>
+      <%= link_to pt.name, plans_path(params.permit(:scope, :status, :tag).merge(plan_type: pt.id)), class: "status-filter #{'status-filter--active' if params[:plan_type] == pt.id}" %>
     <% end %>
   </div>
 <% end %>
 
+<% if params[:tag].present? %>
+  <div class="active-filter">
+    Filtered by tag: <span class="badge badge--tag badge--tag-active"><%= params[:tag] %></span>
+    <%= link_to "✕ Clear", plans_path(params.permit(:scope, :status, :plan_type)), class: "active-filter__clear" %>
+  </div>
+<% end %>
+
 <% if @plans.any? %>
   <div class="plans-list">
     <% @plans.each do |plan| %>
@@ -38,6 +45,13 @@
             <span class="inbox-badge"><%= plan_unread %></span>
           <% end %>
         </div>
+        <% if plan.tags.any? %>
+          <div class="plans-list__tags">
+            <% plan.tags.each do |tag| %>
+              <%= link_to tag.name, plans_path(params.permit(:scope, :status, :plan_type).merge(tag: tag.name)), class: "badge badge--tag #{'badge--tag-active' if params[:tag] == tag.name}" %>
+            <% end %>
+          </div>
+        <% end %>
         <div class="plans-list__meta text-sm text-muted">
           by <%= plan.created_by_user.name %> · v<%= plan.current_revision %> · updated <%= time_ago_in_words(plan.updated_at) %> ago
         </div>

spec/requests/plans_spec.rb

@@ -31,6 +31,41 @@
     expect(response.body).not_to include(bobs_plan.title)
   end
 
+  it "index filters by tag" do
+    plan.tag_names = ["infra"]
+    other = create(:plan, :considering, created_by_user: alice, title: "Other Plan")
+    other.tag_names = ["frontend"]
+    get plans_path(tag: "infra")
+    expect(response).to have_http_status(:success)
+    expect(response.body).to include(plan.title)
+    expect(response.body).not_to include("Other Plan")
+  end
+
+  it "index shows tag badges on plan cards" do
+    plan.tag_names = ["infra", "api"]
+    get plans_path
+    expect(response.body).to include("badge--tag")
+    expect(response.body).to include("infra")
+    expect(response.body).to include("api")
+  end
+
+  it "index shows active tag filter bar" do
+    plan.tag_names = ["infra"]
+    get plans_path(tag: "infra")
+    expect(response.body).to include("active-filter")
+    expect(response.body).to include("infra")
+    expect(response.body).to include("Clear")
+  end
+
+  it "show plan renders tag badges in header" do
+    plan.tag_names = ["infra", "security"]
+    get plan_path(plan)
+    expect(response).to have_http_status(:success)
+    expect(response.body).to include("badge--tag")
+    expect(response.body).to include("infra")
+    expect(response.body).to include("security")
+  end
+
   it "show plan renders successfully" do
     get plan_path(plan)
     expect(response).to have_http_status(:success)