fix: Prioritize diff contexts in script mode for ai chat (#5888)

* fix: prioritize diff contexts and replace underscores with spaces in AI context badges

- Sort context list to show diff contexts first in AvailableContextList.svelte
- Replace underscores with spaces in display names for both AvailableContextList.svelte and ContextElementBadge.svelte
- Improves UX by making diff context names more readable (e.g., "diff with last saved draft" instead of "diff_with_last_saved_draft")

Fixes #5884

Co-authored-by: centdix <centdix@users.noreply.github.com>

* fix

* fix

---------

Co-authored-by: claude[bot] <209825114+claude[bot]@users.noreply.github.com>
Co-authored-by: centdix <centdix@users.noreply.github.com>
Co-authored-by: centdix <farhadg110@gmail.com>

frontend/src/lib/components/copilot/chat/AvailableContextList.svelte

@@ -8,11 +8,24 @@
 	export let stringSearch = ''
 	export let selectedIndex = 0
 
+	// Define priority map for context types
+	const typePriority = {
+		code: 1,
+		diff: 2,
+		default: 3
+	}
+
+	$: sortedAvailableContext = availableContext.sort((a, b) => {
+		const priorityA = typePriority[a.type] || typePriority.default
+		const priorityB = typePriority[b.type] || typePriority.default
+		return priorityA - priorityB
+	})
+
 	$: actualAvailableContext = showAllAvailable
-		? availableContext.filter(
+		? sortedAvailableContext.filter(
 				(c) => !stringSearch || c.title.toLowerCase().includes(stringSearch.toLowerCase())
 			)
-		: availableContext.filter(
+		: sortedAvailableContext.filter(
 				(c) =>
 					!selectedContext.find((sc) => sc.type === c.type && sc.title === c.title) &&
 					(!stringSearch || c.title.toLowerCase().includes(stringSearch.toLowerCase()))
@@ -32,7 +45,7 @@
 				on:click={() => onSelect(element)}
 			>
 				<svelte:component this={ContextIconMap[element.type]} size={16} />
-				{element.title}
+				{element.type === 'diff' ? element.title.replace(/_/g, ' ') : element.title}
 			</button>
 		{/each}
 	{/if}

frontend/src/lib/components/copilot/chat/ContextElementBadge.svelte

@@ -42,7 +42,9 @@
 					<svelte:component this={icon} size={16} />
 				{/if}
 			</button>
-			{contextElement.title}
+			{contextElement.type === 'diff'
+				? contextElement.title.replace(/_/g, ' ')
+				: contextElement.title}
 		</div>
 	</svelte:fragment>
 	<svelte:fragment slot="content">

frontend/src/lib/components/copilot/chat/ContextManager.svelte.ts

@@ -93,7 +93,7 @@ export default class ContextManager {
 			if (scriptOptions.lastSavedCode && scriptOptions.lastSavedCode !== scriptOptions.code) {
 				newAvailableContext.push({
 					type: 'diff',
-					title: 'diff_with_last_saved_draft',
+					title: 'diff_with_last_saved_draft', // can't use spaces in the title, because it will break the word match in the context text area hightlighting logic
 					content: scriptOptions.lastSavedCode ?? '',
 					diff: diffLines(scriptOptions.lastSavedCode ?? '', scriptOptions.code),
 					lang: scriptOptions.lang