fix(dashboard): WebGPU adapter-failure fallback + honest page copy

- /graph now falls back to the Classic renderer when requestAdapter/
  requestDevice fails (previously a dead 'MEMORY FIELD OFFLINE' panel whose
  link pointed back at the same page)
- /duplicates: remove the no-op 'Merge all' button; copy now points at the
  MCP dedup tool, which actually performs reversible merges
- /contradictions: stat card now reports the memories actually analyzed

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

apps/dashboard/src/lib/components/DuplicateCluster.svelte

@@ -2,7 +2,9 @@
   DuplicateCluster — renders a single cosine-similarity cluster from the
   `find_duplicates` MCP tool. Shows similarity bar (color-coded by severity),
   stacked memory cards with type/retention/tags/date, and action controls
-  (Merge all → highest-retention winner, Review → expand, Dismiss → hide).
+  (Review → expand, Dismiss → hide). The "Merge all → winner" button renders
+  ONLY when the host wires `onMerge` to a real merge action — today the merge
+  itself lives in the MCP `dedup` tool, so the dashboard page omits it.
 
   Pure helpers live in `./duplicates-helpers.ts` and are unit-tested there.
   Keep this file focused on rendering + glue.
@@ -160,17 +162,20 @@
 			{/each}
 		</div>
 
-		<!-- Actions — native <button> elements, fully keyboard-accessible. -->
+		<!-- Actions — native <button> elements, fully keyboard-accessible.
+		     Merge renders only when the host actually performs a merge. -->
 		<div class="flex flex-wrap items-center gap-2 pt-1">
-			<button
-				type="button"
-				onclick={handleMerge}
-				aria-label="Merge all memories into the highest-retention winner"
-				class="rounded-lg bg-recall/20 px-3 py-1.5 text-xs font-medium text-recall transition hover:bg-recall/30 focus:outline-none focus-visible:ring-2 focus-visible:ring-recall/60"
-				title="Merge all into highest-retention memory ({(winner.retention * 100).toFixed(0)}%)"
-			>
-				Merge all → winner
-			</button>
+			{#if onMerge}
+				<button
+					type="button"
+					onclick={handleMerge}
+					aria-label="Merge all memories into the highest-retention winner"
+					class="rounded-lg bg-recall/20 px-3 py-1.5 text-xs font-medium text-recall transition hover:bg-recall/30 focus:outline-none focus-visible:ring-2 focus-visible:ring-recall/60"
+					title="Merge all into highest-retention memory ({(winner.retention * 100).toFixed(0)}%)"
+				>
+					Merge all → winner
+				</button>
+			{/if}
 			<button
 				type="button"
 				onclick={() => (expanded = !expanded)}

apps/dashboard/src/lib/components/ObservatoryCanvas.svelte

@@ -7,6 +7,7 @@
 	 * (Increment 3 gate, spec §4).
 	 */
 	import { onMount, onDestroy } from 'svelte';
+	import { base } from '$app/paths';
 	import { ObservatoryEngine, type EngineStatus } from '$lib/observatory/engine';
 	import type { DemoMode } from '$lib/observatory/types';
 
@@ -19,9 +20,15 @@
 		onframe?: (frame: number, fps: number) => void;
 		/** Fired when the engine is running (the route uploads the graph here). */
 		onready?: (engine: ObservatoryEngine) => void;
+		/**
+		 * Fired on every engine status change. Hosts use this to auto-fallback
+		 * when WebGPU boot fails (requestAdapter null / requestDevice throw /
+		 * device lost) even though `'gpu' in navigator` was true.
+		 */
+		onstatus?: (status: EngineStatus) => void;
 	}
 
-	let { demo, seed, freezeFrame = null, onframe, onready }: Props = $props();
+	let { demo, seed, freezeFrame = null, onframe, onready, onstatus }: Props = $props();
 
 	let canvasEl: HTMLCanvasElement;
 	let engine: ObservatoryEngine | null = null;
@@ -38,7 +45,10 @@
 			maxDpr: 2,
 			onFrame: (frame, fps) => onframe?.(frame, fps)
 		});
-		unsubStatus = engine.onStatus((s) => (status = s));
+		unsubStatus = engine.onStatus((s) => {
+			status = s;
+			onstatus?.(s);
+		});
 
 		// Keep the drawing buffer in lockstep with layout size (DPR-clamped).
 		resizeObserver = new ResizeObserver(() => engine?.resize());
@@ -71,7 +81,7 @@
 		<div class="fallback-reason">{status.reason}</div>
 		<div class="fallback-hint">
 			WebGPU is required for the Observatory. Chrome 113+, Edge 113+, or Safari 18+ —
-			the classic <a href="./graph">Graph view</a> works everywhere.
+			the classic <a href="{base}/graph">Graph view</a> works everywhere.
 		</div>
 	</div>
 {/if}

apps/dashboard/src/lib/observatory/ObservatoryStage.svelte

@@ -20,7 +20,7 @@
 	import RescueVerdict from '$lib/observatory/overlays/RescueVerdict.svelte';
 	import ObservatoryCanvas from '$lib/components/ObservatoryCanvas.svelte';
 	import { DEMO_MODES, type DemoMode } from '$lib/observatory/types';
-	import type { ObservatoryEngine } from '$lib/observatory/engine';
+	import type { EngineStatus, ObservatoryEngine } from '$lib/observatory/engine';
 	import { NodeRenderer } from '$lib/observatory/node-renderer';
 	import { BirthRenderer } from '$lib/observatory/birth-renderer';
 	import { RescueRenderer } from '$lib/observatory/rescue-renderer';
@@ -62,6 +62,14 @@
 		 * back with its memory id (the host opens its inspector panel).
 		 */
 		onpick?: (memoryId: string) => void;
+		/**
+		 * Fired when the WebGPU engine cannot run — `'gpu' in navigator` was
+		 * true but requestAdapter() returned null, requestDevice() threw, or
+		 * the device was lost (Linux/VM/blocklisted GPU). Hosts with a
+		 * non-WebGPU renderer switch to it instead of stranding the user on
+		 * the offline panel.
+		 */
+		onfallback?: (reason: string) => void;
 	}
 
 	let {
@@ -74,7 +82,8 @@
 		onexit,
 		embedded = false,
 		chrome = 'full',
-		onpick
+		onpick,
+		onfallback
 	}: Props = $props();
 
 	// GPU picking — screen px → NDC → NodeRenderer.pickAt (one readback/click).
@@ -169,6 +178,13 @@
 		renderer = new NodeRenderer(e);
 	}
 
+	// Adapter/device boot failure or a lost device — let the host swap to a
+	// renderer that works here (the graph page flips to the classic Three.js
+	// inspector) instead of leaving a dead field on screen.
+	function handleStatus(s: EngineStatus) {
+		if (s.state === 'unsupported' || s.state === 'error') onfallback?.(s.reason);
+	}
+
 	// Upload the memory field once the engine AND the graph are both ready.
 	$effect(() => {
 		if (engine && renderer && graphData && !uploaded) {
@@ -299,6 +315,7 @@
 			{freezeFrame}
 			onframe={handleFrame}
 			onready={handleReady}
+			onstatus={handleStatus}
 		/>
 	</div>
 

apps/dashboard/src/routes/(app)/contradictions/+page.svelte

@@ -11,7 +11,6 @@
 		severityColor,
 		severityLabel,
 		truncate,
-		uniqueMemoryCount,
 		avgTrustDelta as avgTrustDeltaFn,
 	} from '$components/contradiction-helpers';
 
@@ -22,6 +21,10 @@
 	// System-wide count from the backend, vs. the derived stats below which
 	// reflect only the pairs the page holds.
 	let totalDetected = $state(0);
+	// How many memories the backend actually scanned — it only analyzes the
+	// most recent `limit` memories, so the stat copy must say so instead of
+	// implying a whole-corpus sweep.
+	let memoriesAnalyzed = $state(0);
 	let loading = $state(true);
 	let error = $state<string | null>(null);
 
@@ -32,10 +35,12 @@
 			const res = await api.contradictions();
 			contradictions = res.contradictions;
 			totalDetected = res.total;
+			memoriesAnalyzed = res.memoriesAnalyzed;
 		} catch (e) {
 			error = e instanceof Error ? e.message : 'Failed to load contradictions';
 			contradictions = [];
 			totalDetected = 0;
+			memoriesAnalyzed = 0;
 		} finally {
 			loading = false;
 		}
@@ -114,10 +119,10 @@
 		focusedPairIndex = i;
 	}
 
-	// --- Stats. `totalDetected` is the backend's system-wide count; everything
-	// else is derived from the pairs the page actually holds so the numbers are
+	// --- Stats. `totalDetected` + `memoriesAnalyzed` come from the backend
+	// (which scans only the most recent `limit` memories); everything else is
+	// derived from the pairs the page actually holds so the numbers are
 	// self-consistent with what the user sees. ---
-	const totalMemoriesInvolved = $derived(uniqueMemoryCount(contradictions));
 	const avgTrustDelta = $derived(avgTrustDeltaFn(contradictions));
 
 	// Map filtered index -> original index in `contradictions` so the
@@ -194,7 +199,7 @@
 				<AnimatedNumber value={totalDetected} />
 			</div>
 			<div class="text-xs text-dim mt-1">
-				contradictions across {totalMemoriesInvolved.toLocaleString()} memories
+				contradictions among the {memoriesAnalyzed.toLocaleString()} most recent memories
 			</div>
 		</div>
 		<div use:reveal={{ delay: 60, y: 12 }} class="p-4 glass rounded-xl lift">

apps/dashboard/src/routes/(app)/duplicates/+page.svelte

@@ -2,8 +2,10 @@
   Memory Hygiene — Duplicate Detection
   Dashboard exposure of the `find_duplicates` MCP tool. Threshold slider
   (0.70-0.95) reruns cosine-similarity clustering. Each cluster renders as a
-  DuplicateCluster with similarity bar, stacked memory cards, and merge /
-  review / dismiss actions.
+  DuplicateCluster with similarity bar, stacked memory cards, and review /
+  dismiss actions. This page is inspection-only: the actual merge lives in
+  the MCP `dedup` tool, so no onMerge is wired here (the merge button only
+  renders when a host provides a real merge action).
 -->
 <script lang="ts">
 	import { onMount, onDestroy } from 'svelte';
@@ -58,14 +60,6 @@
 		dismissed = next;
 	}
 
-	function mergeCluster(key: string, winnerId: string, loserIds: string[]) {
-		// TODO: POST /api/duplicates/merge { winner, losers } when backend ships.
-		// For now we optimistically dismiss the cluster so the UI reflects the
-		// action and rerun counts stay consistent.
-		console.log('Merge cluster', key, { winnerId, loserIds });
-		dismissCluster(key);
-	}
-
 	const visibleClusters = $derived(
 		clusters
 			.map((c) => ({ c, key: clusterKey(c.memories) }))
@@ -92,7 +86,7 @@
 	<PageHeader
 		icon="duplicates"
 		title="Memory Hygiene — Duplicate Detection"
-		subtitle="Cosine-similarity clustering over embeddings. Merges reinforce the winner's FSRS state; losers inherit into the merged node. Dismissed clusters are hidden for this session only."
+		subtitle="Cosine-similarity clustering over embeddings. Inspect each cluster, expand to review, and dismiss false positives (hidden for this session only). To actually merge a cluster, run the MCP dedup tool — it keeps the highest-retention winner."
 		accent="synapse"
 	>
 		<span
@@ -218,7 +212,6 @@
 							memories={c.memories}
 							suggestedAction={c.suggestedAction}
 							onDismiss={() => dismissCluster(key)}
-							onMerge={(winnerId, loserIds) => mergeCluster(key, winnerId, loserIds)}
 						/>
 					</div>
 				</div>

apps/dashboard/src/routes/(app)/graph/+page.svelte

@@ -80,6 +80,18 @@
 		}
 	}
 
+	// `'gpu' in navigator` only proves the API exists — requestAdapter() can
+	// still return null and requestDevice() can still throw (Linux/VM/
+	// blocklisted GPU). The engine reports that through onfallback: switch to
+	// the classic Three.js renderer automatically instead of stranding the
+	// user on a dead "MEMORY FIELD OFFLINE" panel. Deliberately NOT persisted
+	// to localStorage — a machine whose GPU works next session gets the field
+	// back by default.
+	function handleFieldFallback(reason: string) {
+		console.warn(`[graph] WebGPU field unavailable (${reason}) — using the classic renderer.`);
+		renderMode = 'classic';
+	}
+
 	// Filtered graph data based on temporal mode
 	let displayNodes = $derived.by((): GraphNode[] => {
 		if (!graphData) return [];
@@ -324,6 +336,7 @@ disown</code>
 					demo="recall-path"
 					showSwitcher={false}
 					onpick={onNodeSelect}
+					onfallback={handleFieldFallback}
 				/>
 			</div>
 		{:else}
@@ -652,6 +665,12 @@ disown</code>
 				demo={obsDemo}
 				ondemochange={(d) => (obsDemo = d)}
 				onexit={() => (showObservatory = false)}
+				onfallback={(reason) => {
+					// WebGPU boot failed inside the takeover: close it (its offline
+					// panel would link back to this very page) and drop to classic.
+					showObservatory = false;
+					handleFieldFallback(reason);
+				}}
 			/>
 		{/key}
 	</div>