fix: resolve chat path links against the session's operating workspace (#10924)

* fix: resolve chat path links against the session's operating workspace

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RGq2deVkz8qnpfssssKzn7

* fix: hide the chat link drawer button where nothing can open it

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RGq2deVkz8qnpfssssKzn7

* fix: hide the chat tool card open button where nothing can open it

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RGq2deVkz8qnpfssssKzn7

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

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

@@ -713,8 +713,8 @@ export class AIChatManager {
 	workspaceResolver: (() => string | undefined) | undefined = undefined
 
 	// The workspace every workspace-scoped chat action targets — skills, tool
-	// loop, logging, user-message context, and commit. Session-resolved when a
-	// resolver is set, else the globally-active workspace.
+	// loop, logging, user-message context, message rendering, and commit.
+	// Session-resolved when a resolver is set, else the globally-active workspace.
 	get operatingWorkspace(): string | undefined {
 		return this.workspaceResolver?.() ?? get(workspaceStore)
 	}

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

@@ -13,9 +13,21 @@
 	import { messageDraft, segments } from './chatDraft'
 	import { lineCountLabel } from './pasteTokens'
 	import ExpandableImage from '$lib/components/common/image/ExpandableImage.svelte'
+	import { workspaceStore } from '$lib/stores'
 
 	const aiChatManager = getAiChatManager()
 
+	// Paths in a message name items the chat's tools reach, so they resolve against the
+	// operating workspace, never `workspaceStore`: a fork session leaves the store on the
+	// navigated workspace, where a fork-only item resolves to nothing and the rest resolve
+	// to a different copy.
+	const messageWorkspace = $derived.by(() => {
+		// Registers the dependency that `operatingWorkspace`'s own untracked
+		// `get(workspaceStore)` cannot.
+		void $workspaceStore
+		return aiChatManager.operatingWorkspace
+	})
+
 	// Per-message expand/collapse state for paste chips shown in the bubble.
 	let expandedPastes = $state<Set<number>>(new Set())
 
@@ -119,7 +131,7 @@
 		{:else}
 			<div class={twMerge('text-sm py-1 px-2', message.role === 'tool' && 'text-primary py-0')}>
 				{#if message.role === 'assistant'}
-					<div class="px-[1px]"><AssistantMessage {message} /></div>
+					<div class="px-[1px]"><AssistantMessage {message} workspace={messageWorkspace} /></div>
 				{:else if message.role === 'tool'}
 					<div class="px-[1px]"
 						><ToolExecutionDisplay message={message as ToolDisplayMessage} /></div

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

@@ -6,7 +6,6 @@
 	import { thinkingPreferences } from './thinkingPreferences.svelte'
 	import CodeDisplay from './script/CodeDisplay.svelte'
 	import LinkRenderer from './LinkRenderer.svelte'
-	import { workspaceStore } from '$lib/stores'
 	import {
 		extractCandidatePaths,
 		remarkWindmillPaths,
@@ -16,9 +15,12 @@
 
 	interface Props {
 		message: DisplayMessage
+		// Workspace the message's paths are resolved against: the one the chat
+		// operates on, which is not always the one being navigated.
+		workspace: string | undefined
 	}
 
-	let { message }: Props = $props()
+	let { message, workspace }: Props = $props()
 
 	const reasoning = $derived(
 		message.role === 'assistant' ? message.reasoning?.trim() || undefined : undefined
@@ -69,12 +71,11 @@
 	// Only populate the registry for messages that contain path-shaped tokens. The
 	// registry still dedups concurrent calls across messages and workspaces.
 	$effect(() => {
-		const ws = $workspaceStore
-		if (ws && candidatePaths.length > 0) workspaceItemRegistry.ensureLoaded(ws)
+		if (workspace && candidatePaths.length > 0) workspaceItemRegistry.ensureLoaded(workspace)
 	})
 
 	const plugins = $derived.by(() => {
-		const ws = $workspaceStore ?? ''
+		const ws = workspace ?? ''
 		if (!ws || candidatePaths.length === 0) {
 			return [gfmPlugin(), rendererPlugin]
 		}

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

@@ -3,7 +3,10 @@
 	import { ExternalLink, PanelRight } from 'lucide-svelte'
 	import { Button } from '$lib/components/common'
 	import RowIcon from '$lib/components/common/table/RowIcon.svelte'
-	import { runToolDisplayAction } from './createdResourceActions.svelte'
+	import {
+		hasToolDisplayActionHandler,
+		runToolDisplayAction
+	} from './createdResourceActions.svelte'
 	import {
 		workspaceItemAction,
 		type WindmillItemKind,
@@ -27,7 +30,12 @@
 		title
 	}: Props = $props()
 
-	const drawerAction = $derived(workspaceItemAction(wmKind, wmPath, wmTargetKind))
+	// The drawers ride with the docked chat, so a surface can render this pill with nothing
+	// able to open one.
+	const drawerAction = $derived.by(() => {
+		const action = workspaceItemAction(wmKind, wmPath, wmTargetKind)
+		return action && hasToolDisplayActionHandler(action.type) ? action : undefined
+	})
 
 	async function openDrawer(event?: Event) {
 		event?.preventDefault()

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

@@ -28,7 +28,10 @@
 	import MqttIcon from '$lib/components/icons/MqttIcon.svelte'
 	import AmqpIcon from '$lib/components/icons/AmqpIcon.svelte'
 	import NatsIcon from '$lib/components/icons/NatsIcon.svelte'
-	import { runToolDisplayAction } from './createdResourceActions.svelte'
+	import {
+		hasToolDisplayActionHandler,
+		runToolDisplayAction
+	} from './createdResourceActions.svelte'
 	import type { CreatedResourceTriggerKind, ToolDisplayAction } from './shared'
 
 	interface Props {
@@ -122,17 +125,21 @@
 					<div class="truncate text-xs font-semibold text-primary">{card.title}</div>
 					<div class="truncate text-2xs text-secondary">{card.subtitle}</div>
 				</div>
-				<Button
-					size="xs"
-					variant="default"
-					title={action.label}
-					loading={runningActionId === action.id}
-					disabled={runningActionId !== undefined && runningActionId !== action.id}
-					startIcon={{ icon: card.buttonIcon }}
-					onClick={() => handleAction(action)}
-				>
-					Open
-				</Button>
+				<!-- open_created_resource is serviced solely by the docked chat's drawers, so
+				     elsewhere the card stands alone as a record of what the tool created. -->
+				{#if hasToolDisplayActionHandler(action.type)}
+					<Button
+						unifiedSize="sm"
+						variant="default"
+						title={action.label}
+						loading={runningActionId === action.id}
+						disabled={runningActionId !== undefined && runningActionId !== action.id}
+						startIcon={{ icon: card.buttonIcon }}
+						onClick={() => handleAction(action)}
+					>
+						Open
+					</Button>
+				{/if}
 			</div>
 		{/each}
 	</div>

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

@@ -25,6 +25,15 @@ export function registerToolDisplayActionHandler(
 	}
 }
 
+/**
+ * Reactive: reads the `$state` registry, so a component re-renders when a page mounts or
+ * unmounts its handler. Offering an action without checking this yields an affordance whose
+ * only outcome is the unavailable-action toast.
+ */
+export function hasToolDisplayActionHandler(type: ToolDisplayAction['type']): boolean {
+	return toolDisplayActionHandlers[type] !== undefined
+}
+
 export async function runToolDisplayAction(action: ToolDisplayAction): Promise<void> {
 	const handler = toolDisplayActionHandlers[action.type]
 	if (!handler) {

frontend/src/routes/kitchen_sink/+page.svelte

@@ -9,6 +9,7 @@
 	import type { DisplayMessage } from '$lib/components/copilot/chat/shared'
 	import DraggableTabs, { type TabItem } from '$lib/components/common/tabs/DraggableTabs.svelte'
 	import { Globe } from 'lucide-svelte'
+	import { workspaceStore } from '$lib/stores'
 
 	let tab = $state('button')
 
@@ -195,7 +196,7 @@ That's the full round-trip.`
 				<code>CodeDisplay</code> → <code>HighlightCode</code>), constrained to the chat panel width.
 			</div>
 			<div class="border border-border-light rounded-lg p-3 bg-surface" style="max-width: 420px;">
-				<AssistantMessage message={chatMessage} />
+				<AssistantMessage message={chatMessage} workspace={$workspaceStore} />
 			</div>
 		</TabContent>
 		<TabContent value="scrollbar" class="p-4">