diff --git a/internal/agent/retrieval/activity_tracker.go b/internal/agent/retrieval/activity_tracker.go
index 39f3f75b..8b683a19 100644
--- a/internal/agent/retrieval/activity_tracker.go
+++ b/internal/agent/retrieval/activity_tracker.go
@@ -25,6 +25,14 @@ func newActivityTracker(windowMinutes int, maxBoost float32) *activityTracker {
 	}
 }
 
+// windowMinutes returns the decay window in minutes.
+func (at *activityTracker) windowMinutes() int {
+	if at == nil {
+		return 30
+	}
+	return int(at.window.Minutes())
+}
+
 // observe records that the given concepts were just seen in watcher activity.
 // Upserts timestamps and lazily evicts expired entries when the map grows large.
 func (at *activityTracker) observe(concepts []string) {
diff --git a/internal/agent/retrieval/agent.go b/internal/agent/retrieval/agent.go
index 4944c159..c51642c7 100644
--- a/internal/agent/retrieval/agent.go
+++ b/internal/agent/retrieval/agent.go
@@ -236,6 +236,11 @@ func (ra *RetrievalAgent) ActivitySnapshot() map[string]time.Time {
 	return ra.activity.snapshot()
 }
 
+// ActivityWindowMinutes returns the activity tracker's decay window in minutes.
+func (ra *RetrievalAgent) ActivityWindowMinutes() int {
+	return ra.activity.windowMinutes()
+}
+
 // SyncActivity replaces the activity tracker state with the given snapshot.
 // Used by MCP processes to sync activity from the daemon's REST API.
 func (ra *RetrievalAgent) SyncActivity(snap map[string]time.Time) {
diff --git a/internal/api/routes/activity.go b/internal/api/routes/activity.go
index 9d396700..a5a268e5 100644
--- a/internal/api/routes/activity.go
+++ b/internal/api/routes/activity.go
@@ -11,7 +11,8 @@ import (
 
 // ActivityResponse is the JSON response for the activity endpoint.
 type ActivityResponse struct {
-	Concepts map[string]time.Time `json:"concepts"`
+	Concepts      map[string]time.Time `json:"concepts"`
+	WindowMinutes int                  `json:"window_minutes"`
 }
 
 // HandleActivity returns the retrieval agent's current activity tracker state.
@@ -23,7 +24,11 @@ func HandleActivity(retriever *retrieval.RetrievalAgent, log *slog.Logger) http.
 			snap = make(map[string]time.Time)
 		}
 		w.Header().Set("Content-Type", "application/json")
-		if err := json.NewEncoder(w).Encode(ActivityResponse{Concepts: snap}); err != nil {
+		resp := ActivityResponse{
+			Concepts:      snap,
+			WindowMinutes: retriever.ActivityWindowMinutes(),
+		}
+		if err := json.NewEncoder(w).Encode(resp); err != nil {
 			log.Warn("failed to encode activity response", "error", err)
 		}
 	}
diff --git a/internal/api/routes/patterns.go b/internal/api/routes/patterns.go
index 142eefdb..454b1c13 100644
--- a/internal/api/routes/patterns.go
+++ b/internal/api/routes/patterns.go
@@ -2,6 +2,8 @@ package routes
 
 import (
 	"context"
+	"encoding/json"
+	"errors"
 	"log/slog"
 	"net/http"
 	"time"
@@ -79,6 +81,58 @@ func HandleListAbstractions(s store.Store, log *slog.Logger) http.HandlerFunc {
 	}
 }
 
+// HandleArchivePattern archives a single pattern by ID.
+// PATCH /api/v1/patterns/{id}  body: {"state": "archived"}
+func HandleArchivePattern(s store.Store, log *slog.Logger) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		id := r.PathValue("id")
+		if id == "" {
+			writeError(w, http.StatusBadRequest, "pattern ID is required", "INVALID_REQUEST")
+			return
+		}
+
+		var body struct {
+			State string `json:"state"`
+		}
+		if err := json.NewDecoder(r.Body).Decode(&body); err != nil || body.State == "" {
+			writeError(w, http.StatusBadRequest, "state field is required (e.g. \"archived\")", "INVALID_REQUEST")
+			return
+		}
+		if body.State != "active" && body.State != "archived" {
+			writeError(w, http.StatusBadRequest, "state must be \"active\" or \"archived\"", "INVALID_REQUEST")
+			return
+		}
+
+		ctx, cancel := context.WithTimeout(r.Context(), 5*time.Second)
+		defer cancel()
+
+		p, err := s.GetPattern(ctx, id)
+		if err != nil {
+			if errors.Is(err, store.ErrNotFound) {
+				writeError(w, http.StatusNotFound, "pattern not found", "NOT_FOUND")
+				return
+			}
+			log.Error("failed to get pattern", "id", id, "error", err)
+			writeError(w, http.StatusInternalServerError, "failed to get pattern", "STORE_ERROR")
+			return
+		}
+
+		p.State = body.State
+		p.UpdatedAt = time.Now()
+		if err := s.UpdatePattern(ctx, p); err != nil {
+			log.Error("failed to update pattern", "id", id, "error", err)
+			writeError(w, http.StatusInternalServerError, "failed to update pattern", "STORE_ERROR")
+			return
+		}
+
+		log.Info("pattern state updated", "id", id, "state", body.State)
+		writeJSON(w, http.StatusOK, map[string]interface{}{
+			"id":    id,
+			"state": body.State,
+		})
+	}
+}
+
 // HandleListProjects returns all known projects.
 // GET /api/v1/projects
 func HandleListProjects(s store.Store, log *slog.Logger) http.HandlerFunc {
diff --git a/internal/api/server.go b/internal/api/server.go
index 2e99abac..3a118ab9 100644
--- a/internal/api/server.go
+++ b/internal/api/server.go
@@ -118,6 +118,7 @@ func (s *Server) registerRoutes() {
 
 	// Patterns and abstractions
 	s.mux.HandleFunc("GET /api/v1/patterns", routes.HandleListPatterns(s.deps.Store, s.deps.Log))
+	s.mux.HandleFunc("PATCH /api/v1/patterns/{id}", routes.HandleArchivePattern(s.deps.Store, s.deps.Log))
 	s.mux.HandleFunc("GET /api/v1/abstractions", routes.HandleListAbstractions(s.deps.Store, s.deps.Log))
 	s.mux.HandleFunc("GET /api/v1/projects", routes.HandleListProjects(s.deps.Store, s.deps.Log))
 
diff --git a/internal/web/static/index.html b/internal/web/static/index.html
index cb491f56..5674dd3e 100644
--- a/internal/web/static/index.html
+++ b/internal/web/static/index.html
@@ -944,6 +944,28 @@
             text-transform: uppercase; letter-spacing: 0.05em;
             padding: 8px 8px 4px; margin-top: 8px;
         }
+        .concept-row {
+            display: flex; align-items: center; gap: 8px;
+            padding: 4px 8px; font-size: 0.78rem;
+        }
+        .concept-name { flex: 0 0 auto; min-width: 80px; color: var(--text-primary); font-weight: 500; }
+        .concept-bar-bg {
+            flex: 1; height: 4px; border-radius: 2px;
+            background: var(--bg-tertiary);
+        }
+        .concept-bar-fill {
+            height: 100%; border-radius: 2px;
+            background: var(--accent-green);
+            transition: width 0.3s ease;
+        }
+        .concept-time { flex: 0 0 auto; font-size: 0.7rem; color: var(--text-muted); min-width: 45px; text-align: right; }
+        .pattern-archive-btn {
+            float: right; background: none; border: 1px solid var(--border-color);
+            color: var(--text-muted); cursor: pointer; font-size: 0.7rem;
+            padding: 2px 8px; border-radius: var(--radius-sm);
+            transition: all 0.15s;
+        }
+        .pattern-archive-btn:hover { background: var(--warning-bg); color: var(--warning-text); border-color: var(--warning-text); }
         .event-item {
             display: flex; align-items: flex-start; gap: 10px;
             padding: 8px; border-radius: var(--radius-sm);
@@ -1679,6 +1701,8 @@ <h3>Activity</h3>
                 <button class="drawer-close" onclick="toggleDrawer()">&times;</button>
             </div>
             <div class="drawer-body">
+                <div class="drawer-section-title">Active Concepts</div>
+                <div id="conceptsContainer" style="margin-bottom:12px"></div>
                 <div class="drawer-section-title">Insights</div>
                 <div id="insightsContainer"></div>
                 <div class="drawer-section-title" style="margin-top:16px">Live Events</div>
@@ -2087,7 +2111,8 @@ <h3>Activity</h3>
             var concepts = (p.concepts || []).slice(0, 5);
             var evidenceCount = (p.evidence_ids || []).length;
             var age = p.created_at ? relativeTime(p.created_at) : '';
-            var html = '<div class="pattern-card"><div class="pattern-title">' + escapeHtml(p.title || 'Untitled');
+            var html = '<div class="pattern-card" data-pattern-id="' + escapeHtml(p.id) + '"><div class="pattern-title">' + escapeHtml(p.title || 'Untitled');
+            html += '<button class="pattern-archive-btn" onclick="archivePattern(\'' + escapeHtml(p.id) + '\', this)">Archive</button>';
             if (p.project) html += ' <span style="color:var(--accent-blue);font-size:0.8rem">[' + escapeHtml(p.project) + ']</span>';
             html += '</div><span class="badge badge-type">' + escapeHtml(p.pattern_type || 'pattern') + '</span>';
             if (p.state && p.state !== 'active') html += ' <span class="badge" style="background:var(--warning-bg);color:var(--warning-text)">' + escapeHtml(p.state) + '</span>';
@@ -2103,6 +2128,20 @@ <h3>Activity</h3>
         }).join('');
     }
 
+    async function archivePattern(id, btn) {
+        try {
+            var resp = await fetch(CONFIG.API_BASE + '/patterns/' + id, {
+                method: 'PATCH',
+                headers: {'Content-Type': 'application/json'},
+                body: JSON.stringify({state: 'archived'})
+            });
+            if (!resp.ok) { showToast('Failed to archive pattern', 'error'); return; }
+            var card = btn.closest('.pattern-card');
+            if (card) { card.style.transition = 'opacity 0.3s'; card.style.opacity = '0'; setTimeout(function() { card.remove(); }, 300); }
+            showToast('Pattern archived');
+        } catch(e) { showToast('Failed to archive pattern', 'error'); }
+    }
+
     async function loadAbstractions(section) {
         var data = await fetchJSON('/abstractions?limit=20');
         var abstractions = data.abstractions || [];
@@ -2673,11 +2712,52 @@ <h3>Activity</h3>
     }
 
     // ── Activity Drawer ──
+    var _conceptsInterval = null;
     function toggleDrawer() {
         state.drawerOpen = !state.drawerOpen;
         document.getElementById('activityDrawer').classList.toggle('open', state.drawerOpen);
         document.getElementById('activityBackdrop').classList.toggle('open', state.drawerOpen);
-        if (state.drawerOpen) { state.unreadEvents = 0; updateBadge(); }
+        if (state.drawerOpen) {
+            state.unreadEvents = 0; updateBadge();
+            loadActivityConcepts();
+            _conceptsInterval = setInterval(loadActivityConcepts, 10000);
+        } else if (_conceptsInterval) {
+            clearInterval(_conceptsInterval);
+            _conceptsInterval = null;
+        }
+    }
+
+    async function loadActivityConcepts() {
+        try {
+            var resp = await fetch(CONFIG.API_BASE + '/activity');
+            if (!resp.ok) return;
+            var data = await resp.json();
+            var windowMs = (data.window_minutes || 30) * 60 * 1000;
+            var now = Date.now();
+            var concepts = [];
+            for (var name in (data.concepts || {})) {
+                var ts = new Date(data.concepts[name]).getTime();
+                var elapsed = now - ts;
+                var remaining = windowMs - elapsed;
+                if (remaining > 0) {
+                    concepts.push({ name: name, remaining: remaining, pct: (remaining / windowMs) * 100 });
+                }
+            }
+            concepts.sort(function(a, b) { return b.remaining - a.remaining; });
+            var container = document.getElementById('conceptsContainer');
+            if (concepts.length === 0) {
+                container.innerHTML = '<div style="font-size:0.75rem;color:var(--text-muted);padding:4px 8px">No active concepts (watcher idle)</div>';
+                return;
+            }
+            container.innerHTML = concepts.slice(0, 15).map(function(c) {
+                var mins = Math.ceil(c.remaining / 60000);
+                var color = c.pct > 50 ? 'var(--accent-green)' : c.pct > 20 ? 'var(--accent-yellow, #f0c040)' : 'var(--accent-pink)';
+                return '<div class="concept-row">' +
+                    '<span class="concept-name">' + escapeHtml(c.name) + '</span>' +
+                    '<div class="concept-bar-bg"><div class="concept-bar-fill" style="width:' + Math.round(c.pct) + '%;background:' + color + '"></div></div>' +
+                    '<span class="concept-time">' + mins + 'm</span></div>';
+            }).join('');
+        } catch(e) { /* ignore */ }
     }
 
     function updateBadge() {