fix(translate): replace fromStore+ with +subscribe to prevent reactive loop, add runComplete flag, show error_message, collapsible run results

- TranslationRunGlobalIndicator: replace fromStore + 6x  with
  (() => store.subscribe()) to prevent accumulating render_effect
  instances via createSubscriber that caused infinite Svelte reactive flush
- translate/[id]/+page.svelte: add runComplete flag to hide progress bar
  after completion without touching the store; add collapsible run detail
  cards with status badge, counts, and error_message; filter invalid runs
- translationRun.js: remove stale guard (no longer needed)
- Sidebar.svelte: fix mobile overlay close on route change
- docs/adr/ADR-0007-rejected-fromStore-derived.md: document REJECTED pattern

frontend/src/lib/components/layout/Sidebar.svelte

@@ -187,12 +187,11 @@
     closeMobile();
   }
 
-  // Close mobile overlay on route change
+  // Close mobile overlay on route change — depends only on page.url.pathname, NOT isMobileOpen.
+  // Otherwise clicking the burger (which sets isMobileOpen=true) would immediately close it.
   $effect(() => {
-    if (isMobileOpen) {
-      page.url.pathname;
-      closeMobile();
-    }
+    const _pathname = page.url.pathname;
+    closeMobile();
   });
 
   onMount(() => {

frontend/src/lib/components/translate/TranslationRunGlobalIndicator.svelte

@@ -9,7 +9,6 @@
 <!-- @UX_FEEDBACK Rich stats during active run; compact auto-dismiss for terminal states -->
 <script>
 	import { translationRunStore, stopTranslationRun } from '$lib/stores/translationRun.js';
-	import { fromStore } from 'svelte/store';
 	import { page } from '$app/state';
 	import { goto } from '$app/navigation';
 	import { t } from '$lib/i18n';
@@ -17,7 +16,17 @@
 	import { cancelRun } from '$lib/api/translate.js';
 	import { addToast } from '$lib/toasts.js';
 
-	const runState = fromStore(translationRunStore);
+	// Subscribe to store via $effect + subscribe (NOT fromStore + $derived).
+	// @REJECTED fromStore + multiple $derived(runState.current.xxx) creates render_effect
+	// instances via createSubscriber on every $derived re-evaluation. Over time these
+	// accumulate and trigger an infinite Svelte reactive flush loop after ~300 polls.
+	// @RATIONALE $effect(() => store.subscribe(s => state = s)) creates exactly ONE
+	// subscription per component lifecycle — no accumulating render_effects.
+	let storeState = $state({ uxState: 'idle', totalRecords: 0, successfulRecords: 0, failedRecords: 0, skippedRecords: 0, progressPct: 0, runId: null, jobId: null });
+	$effect(() => {
+		const unsub = translationRunStore.subscribe(s => { storeState = s; });
+		return () => unsub();
+	});
 
 	// Hide on the translate page itself to avoid duplication
 	let isOnTranslatePage = $derived(
@@ -29,7 +38,7 @@
 	let dismissed = $state(false);
 	let isCancelling = $state(false);
 
-	let uxState = $derived(runState.current?.uxState || 'idle');
+	let uxState = $derived(storeState?.uxState || 'idle');
 
 	let show = $derived.by(() => {
 		if (dismissed) return false;
@@ -52,11 +61,11 @@
 		return '';
 	});
 
-	let totalRecords = $derived(runState.current?.totalRecords || 0);
-	let successfulRecords = $derived(runState.current?.successfulRecords || 0);
-	let failedRecords = $derived(runState.current?.failedRecords || 0);
-	let skippedRecords = $derived(runState.current?.skippedRecords || 0);
-	let progressPct = $derived(runState.current?.progressPct || 0);
+	let totalRecords = $derived(storeState?.totalRecords || 0);
+	let successfulRecords = $derived(storeState?.successfulRecords || 0);
+	let failedRecords = $derived(storeState?.failedRecords || 0);
+	let skippedRecords = $derived(storeState?.skippedRecords || 0);
+	let progressPct = $derived(storeState?.progressPct || 0);
 
 	// Auto-dismiss terminal states after a few seconds
 	$effect(() => {
@@ -78,7 +87,7 @@
 	});
 
 	function handleClick() {
-		const jobId = runState.current?.jobId;
+		const jobId = storeState?.jobId;
 		if (jobId) {
 			goto(`/translate/${jobId}`);
 		}
@@ -86,7 +95,7 @@
 
 	async function handleCancel(e) {
 		e.stopPropagation();
-		const runId = runState.current?.runId;
+		const runId = storeState?.runId;
 		if (!runId || isCancelling) return;
 		isCancelling = true;
 		try {

frontend/src/lib/stores/translationRun.js

@@ -149,16 +149,6 @@ async function pollStatus() {
 		const data = await fetchRunStatus(currentState.runId);
 		if (!data) return;
 
-		// Guard: if runId was cleared (by handleRunComplete clearing it via updateTranslationRunState
-		// while we were awaiting fetchRunStatus), skip the store update to avoid restoring the runId
-		// and causing the progress bar to stay visible indefinitely.
-		let latestState;
-		translationRunStore.subscribe(s => { latestState = s; })();
-		if (!latestState || !latestState.runId) {
-			stopTranslationRun();
-			return;
-		}
-
 		const s = data?.status;
 		const insertS = data?.insert_status;