diff --git a/frontend/src/lib/components/copilot/chat/AIChatDisplay.svelte b/frontend/src/lib/components/copilot/chat/AIChatDisplay.svelte
index 82dcbc2dcd..8428f568a1 100644
--- a/frontend/src/lib/components/copilot/chat/AIChatDisplay.svelte
+++ b/frontend/src/lib/components/copilot/chat/AIChatDisplay.svelte
@@ -36,6 +36,7 @@
 	import ContextUsageIndicator from './ContextUsageIndicator.svelte'
 	import AIChatModelSettings from './AIChatModelSettings.svelte'
 	import AssistantSettingsModal from './AssistantSettingsModal.svelte'
+	import AgentContextSummary from './contextSummary/AgentContextSummary.svelte'
 	import { SkillsMenu } from './skills/skillsMenu.svelte'
 	import { McpMenu } from '$lib/components/mcp/mcpMenu.svelte'
 	import ChatMode from './ChatMode.svelte'
@@ -1262,4 +1263,18 @@ the panel, or the Escape-to-stop focus check would wrongly reject them. -->
 			</div>
 		{/if}
 	</div>
+	<!-- After the composer, so an empty session puts the input at the top and what the
+	     agent is carrying underneath it. -->
+	{#if messages.length === 0 && chatHost.mode === AIMode.GLOBAL && chatHost.isSessionChat}
+		<div class="flex-1 min-h-0 overflow-y-auto">
+			<!-- Same max width and gutter as the composer above, so the two line up. -->
+			<div
+				class={wideLayout
+					? 'w-full max-w-3xl mx-auto px-6 pt-8 pb-2'
+					: 'w-full max-w-2xl mx-auto px-2 pt-8 pb-2'}
+			>
+				<AgentContextSummary onManage={(section) => assistantSettings?.open(section)} />
+			</div>
+		</div>
+	{/if}
 </div>
diff --git a/frontend/src/lib/components/copilot/chat/agentContext.ts b/frontend/src/lib/components/copilot/chat/agentContext.ts
index 99b334bcd5..6f8c4e3246 100644
--- a/frontend/src/lib/components/copilot/chat/agentContext.ts
+++ b/frontend/src/lib/components/copilot/chat/agentContext.ts
@@ -10,6 +10,9 @@ export type ToolSummary = {
 	 * `SchemaViewer` reads it to mark the rows and renders nothing without it, and a
 	 * tool whose arguments are all optional legitimately omits it. */
 	parameters: Record<string, any>
+	/** The tool reads and never changes anything, which is what plan mode admits.
+	 * `planModeSafe` fails closed there, so an untagged tool counts as a write here too. */
+	readOnly: boolean
 }
 
 /** Tool definitions as the modal lists them: name-sorted, so a list of dozens is
@@ -19,7 +22,8 @@ export function summarizeTools(tools: readonly Tool<any>[]): ToolSummary[] {
 		.map((t) => ({
 			name: t.def.function.name,
 			description: t.def.function.description ?? '',
-			parameters: { required: [], ...(t.def.function.parameters ?? {}) }
+			parameters: { required: [], ...(t.def.function.parameters ?? {}) },
+			readOnly: t.planModeSafe === true
 		}))
 		.sort((a, b) => a.name.localeCompare(b.name))
 }
diff --git a/frontend/src/lib/components/copilot/chat/contextSummary/AgentContextSummary.svelte b/frontend/src/lib/components/copilot/chat/contextSummary/AgentContextSummary.svelte
new file mode 100644
index 0000000000..84c85c3a4a
--- /dev/null
+++ b/frontend/src/lib/components/copilot/chat/contextSummary/AgentContextSummary.svelte
@@ -0,0 +1,154 @@
+<script lang="ts">
+	// What the session's agent is carrying, shown while the session has no messages.
+	// Everything here is read from the same places the system prompt is built from.
+	import { workspaceStore } from '$lib/stores'
+	import { ResourceService } from '$lib/gen'
+	import { getCustomPromptParts } from '$lib/aiStore'
+	import { sendUserToast } from '$lib/toast'
+	import { isMcpEnabled, setMcpEnabled } from '$lib/components/mcp/enabledServers'
+	import {
+		isOwnOrSharedMcpPath,
+		MCP_LIST_PER_PAGE,
+		mcpViewer
+	} from '$lib/components/mcp/ownServers'
+	import { AIMode } from '../AIChatManager.svelte'
+	import { getAiChatManager } from '../aiChatManagerContext'
+	import { summarizeTools } from '../agentContext'
+	import { isSkillEnabled, setSkillEnabled } from '../skills/enabledSkills'
+	import { listSkillResources } from '../skills/skillResources'
+	import ContextSummaryRows from './ContextSummaryRows.svelte'
+	import type {
+		AgentContext,
+		ContextMcpServer,
+		ContextSectionId,
+		ContextSkill,
+		ContextSummaryActions
+	} from './contextSummary'
+
+	let { onManage }: { onManage: (section: ContextSectionId) => void } = $props()
+
+	const aiChatManager = getAiChatManager()
+
+	// The workspace every list here is read under — a session operates on its own
+	// (possibly forked) workspace without switching `workspaceStore`.
+	let ws = $derived(aiChatManager.operatingWorkspace ?? $workspaceStore ?? '')
+
+	// A session whose fork is still staged has no workspace of its own yet, so `ws` is
+	// the PARENT: a switch flipped now would be stored under it and stop applying the
+	// moment the first send commits the fork.
+	let toggleBlockedReason = $derived(
+		aiChatManager.sessionContextResolver?.()?.pendingForkOf
+			? 'This session creates its workspace on the first message. Send one before changing this.'
+			: undefined
+	)
+
+	// The full lists, disabled entries included — `aiChatManager` keeps only what is on,
+	// and a switch needs the rows it can turn back on. One promise per workspace, so a
+	// workspace change replaces it rather than racing it.
+	let listsPromise = $derived(loadLists(ws))
+	// Flips applied since the lists were read, so a switch lands without a reload. One map
+	// per kind: a skill and a server can hold the same resource path.
+	let skillOverrides = $state<Record<string, boolean>>({})
+	let mcpOverrides = $state<Record<string, boolean>>({})
+
+	async function loadLists(
+		workspace: string
+	): Promise<{ skills: ContextSkill[]; mcpServers: ContextMcpServer[] }> {
+		if (!workspace) return { skills: [], mcpServers: [] }
+		const [skills, mcpServers] = await Promise.all([
+			loadSkills(workspace),
+			loadMcpServers(workspace)
+		])
+		return { skills, mcpServers }
+	}
+
+	async function loadSkills(workspace: string): Promise<ContextSkill[]> {
+		try {
+			return (await listSkillResources(workspace)).skills.map(({ path, name, description }) => ({
+				path,
+				name,
+				description: description ?? '',
+				enabled: isSkillEnabled(workspace, path)
+			}))
+		} catch (e) {
+			console.error('Failed to load AI skills', e)
+			return []
+		}
+	}
+
+	async function loadMcpServers(workspace: string): Promise<ContextMcpServer[]> {
+		try {
+			const [resources, viewer] = await Promise.all([
+				ResourceService.listResource({
+					workspace,
+					resourceType: 'mcp',
+					perPage: MCP_LIST_PER_PAGE
+				}),
+				mcpViewer(workspace)
+			])
+			return resources
+				.filter((r) => isOwnOrSharedMcpPath(r.path, r.extra_perms, viewer))
+				.map((r) => ({
+					path: r.path,
+					name: r.path,
+					description: r.description,
+					enabled: isMcpEnabled(workspace, r.path)
+				}))
+		} catch (e) {
+			console.error('Failed to load MCP connections', e)
+			return []
+		}
+	}
+
+	function applyOverrides<T extends { path: string; enabled: boolean }>(
+		rows: T[],
+		overrides: Record<string, boolean>
+	): T[] {
+		return rows.map((row) => ({ ...row, enabled: overrides[row.path] ?? row.enabled }))
+	}
+
+	function buildContext(lists: {
+		skills: ContextSkill[]
+		mcpServers: ContextMcpServer[]
+	}): AgentContext {
+		return {
+			workspace: ws,
+			// Exactly what the chat loop sends: plan mode's transition tool is registered
+			// alongside `tools` there, so listing only `tools` would under-report.
+			tools: summarizeTools([...aiChatManager.tools, ...aiChatManager.planMode.tools]).map(
+				({ name, description, readOnly }) => ({ name, description, readOnly })
+			),
+			skills: applyOverrides(lists.skills, skillOverrides),
+			mcpServers: applyOverrides(lists.mcpServers, mcpOverrides),
+			instructions: getCustomPromptParts(AIMode.GLOBAL)
+		}
+	}
+
+	const actions: ContextSummaryActions = {
+		onToggleSkill: async (path, enabled) => {
+			if (!setSkillEnabled(ws, path, enabled)) {
+				sendUserToast('Could not save this choice for this account.', true)
+				return
+			}
+			skillOverrides[path] = enabled
+			// The prompt lists exactly the skills that are on, so it has to be rebuilt
+			// before the next message rather than on the next mode change.
+			await aiChatManager.refreshGlobalSkills(ws)
+		},
+		onToggleMcp: async (path, enabled) => {
+			const target = ws
+			if (!setMcpEnabled(target, path, enabled)) {
+				sendUserToast('Could not save the selection for this account.', true)
+				return
+			}
+			mcpOverrides[path] = enabled
+			if (target !== ws) return
+			await aiChatManager.refreshMcpServers(target)
+		},
+		onManage
+	}
+</script>
+
+{#await listsPromise then lists}
+	<ContextSummaryRows ctx={buildContext(lists)} {actions} {toggleBlockedReason} />
+{/await}
diff --git a/frontend/src/lib/components/copilot/chat/contextSummary/ContextSectionDetail.svelte b/frontend/src/lib/components/copilot/chat/contextSummary/ContextSectionDetail.svelte
new file mode 100644
index 0000000000..99108e45a8
--- /dev/null
+++ b/frontend/src/lib/components/copilot/chat/contextSummary/ContextSectionDetail.svelte
@@ -0,0 +1,152 @@
+<script lang="ts">
+	import { Button } from '$lib/components/common'
+	import Toggle from '$lib/components/Toggle.svelte'
+	import {
+		summarizeContextSection,
+		type AgentContext,
+		type ContextSectionId,
+		type ContextTool,
+		type ContextSummaryActions
+	} from './contextSummary'
+
+	let {
+		ctx,
+		section,
+		actions,
+		toggleBlockedReason
+	}: {
+		ctx: AgentContext
+		section: ContextSectionId
+		actions: ContextSummaryActions
+		/** Why the switches are disabled, when they are — a session whose fork is still
+		 * staged would store the choice under the parent workspace. */
+		toggleBlockedReason?: string
+	} = $props()
+
+	let summary = $derived(summarizeContextSection(ctx, section))
+	let expandedInstructions = $state<Record<string, boolean>>({})
+</script>
+
+{#snippet toolChips(tools: ContextTool[])}
+	<div class="flex flex-wrap gap-1">
+		{#each tools as tool (tool.name)}
+			<span
+				class="font-mono text-2xs px-1.5 py-0.5 rounded bg-surface-secondary text-secondary"
+				title={tool.description}>{tool.name}</span
+			>
+		{/each}
+	</div>
+{/snippet}
+
+{#snippet scope()}
+	<span class="text-2xs text-hint">Applies to all your sessions in {ctx.workspace}</span>
+{/snippet}
+
+{#snippet footer()}
+	<div class="flex justify-end">
+		<Button variant="subtle" unifiedSize="xs" onclick={() => actions.onManage(section)}>
+			Manage
+		</Button>
+	</div>
+{/snippet}
+
+<div class="flex flex-col gap-2">
+	{#if summary.empty}
+		<div class="flex items-center gap-2">
+			<span class="text-2xs text-hint">{summary.emptyText}</span>
+			{#if summary.emptyAction}
+				<Button variant="default" unifiedSize="xs" onclick={() => actions.onManage(section)}>
+					{summary.emptyAction}
+				</Button>
+			{/if}
+		</div>
+	{:else if section === 'tools'}
+		{#each [{ key: 'read', label: 'Read', tools: ctx.tools.filter((t) => t.readOnly) }, { key: 'write', label: 'Write', tools: ctx.tools.filter((t) => !t.readOnly) }] as group (group.key)}
+			{#if group.tools.length}
+				<div class="flex flex-col gap-1">
+					<span class="text-2xs font-semibold text-emphasis"
+						>{group.label}<span class="font-normal text-hint"> · {group.tools.length}</span></span
+					>
+					{@render toolChips(group.tools)}
+				</div>
+			{/if}
+		{/each}
+		{@render footer()}
+	{:else if section === 'skills'}
+		{@render scope()}
+		<div class="flex flex-col">
+			{#each ctx.skills as skill (skill.path)}
+				<div class="flex items-center gap-3 py-1">
+					<div class="flex flex-col min-w-0 grow">
+						<span class="text-xs {skill.enabled ? 'text-primary' : 'text-disabled'} truncate"
+							>{skill.name}</span
+						>
+						{#if skill.description}
+							<span class="text-2xs text-secondary truncate">{skill.description}</span>
+						{/if}
+					</div>
+					<Toggle
+						size="2xs"
+						disabled={toggleBlockedReason !== undefined}
+						options={{ title: toggleBlockedReason }}
+						checked={skill.enabled}
+						on:change={(e) => actions.onToggleSkill(skill.path, e.detail)}
+					/>
+				</div>
+			{/each}
+		</div>
+		{@render footer()}
+	{:else if section === 'mcp'}
+		{@render scope()}
+		<div class="flex flex-col">
+			{#each ctx.mcpServers as server (server.path)}
+				<div class="flex items-center gap-3 py-1">
+					<div class="flex flex-col min-w-0 grow">
+						<span class="text-xs {server.enabled ? 'text-primary' : 'text-disabled'} truncate"
+							>{server.name}</span
+						>
+						{#if server.description}
+							<span class="text-2xs text-secondary truncate">{server.description}</span>
+						{/if}
+					</div>
+					<Toggle
+						size="2xs"
+						disabled={toggleBlockedReason !== undefined}
+						options={{ title: toggleBlockedReason }}
+						checked={server.enabled}
+						on:change={(e) => actions.onToggleMcp(server.path, e.detail)}
+					/>
+				</div>
+			{/each}
+		</div>
+		{@render footer()}
+	{:else if section === 'instructions'}
+		{#each [{ key: 'workspace', label: 'Workspace', text: ctx.instructions.workspace }, { key: 'user', label: 'Personal', text: ctx.instructions.user }] as block (block.key)}
+			<div class="flex flex-col gap-0.5">
+				<span class="text-2xs font-semibold text-emphasis">{block.label}</span>
+				{#if block.text?.trim()}
+					<p
+						class="text-2xs text-secondary whitespace-pre-wrap {expandedInstructions[block.key]
+							? ''
+							: 'line-clamp-3'}">{block.text.trim()}</p
+					>
+					{#if block.text.trim().split('\n').length > 3 || block.text.length > 240}
+						<button
+							type="button"
+							class="self-start text-2xs text-accent hover:underline"
+							onclick={() => (expandedInstructions[block.key] = !expandedInstructions[block.key])}
+							>{expandedInstructions[block.key] ? 'Show less' : 'Show more'}</button
+						>
+					{/if}
+				{:else}
+					<span class="text-2xs text-hint">None</span>
+				{/if}
+			</div>
+		{/each}
+		<div class="flex justify-end">
+			<Button variant="subtle" unifiedSize="xs" onclick={() => actions.onManage(section)}>
+				Edit
+			</Button>
+		</div>
+	{/if}
+</div>
diff --git a/frontend/src/lib/components/copilot/chat/contextSummary/ContextSummaryRows.svelte b/frontend/src/lib/components/copilot/chat/contextSummary/ContextSummaryRows.svelte
new file mode 100644
index 0000000000..5546047c38
--- /dev/null
+++ b/frontend/src/lib/components/copilot/chat/contextSummary/ContextSummaryRows.svelte
@@ -0,0 +1,57 @@
+<script lang="ts">
+	import { ChevronRight } from 'lucide-svelte'
+	import { slide } from 'svelte/transition'
+	import ContextSectionDetail from './ContextSectionDetail.svelte'
+	import {
+		summarizeContext,
+		type AgentContext,
+		type ContextSectionId,
+		type ContextSummaryActions
+	} from './contextSummary'
+	import { CONTEXT_SECTION_ICONS } from './sectionIcons'
+
+	let {
+		ctx,
+		actions,
+		toggleBlockedReason
+	}: {
+		ctx: AgentContext
+		actions: ContextSummaryActions
+		toggleBlockedReason?: string
+	} = $props()
+
+	let sections = $derived(summarizeContext(ctx))
+	// Each row opens and closes on its own: comparing two sections means having both open.
+	let open = $state<Partial<Record<ContextSectionId, boolean>>>({})
+</script>
+
+<div class="flex flex-col w-full">
+	<span class="text-2xs text-secondary px-2 pb-1">Context</span>
+	{#each sections as s (s.id)}
+		{@const Icon = CONTEXT_SECTION_ICONS[s.id]}
+		<button
+			type="button"
+			class="flex items-center gap-2 px-2 py-1 rounded-md hover:bg-surface-hover text-left min-w-0"
+			aria-expanded={open[s.id] ?? false}
+			onclick={() => (open[s.id] = !open[s.id])}
+		>
+			<ChevronRight
+				size={12}
+				class="shrink-0 text-hint transition-transform {open[s.id] ? 'rotate-90' : ''}"
+			/>
+			<Icon size={12} class="shrink-0 {s.empty ? 'text-hint' : 'text-tertiary'}" />
+			<span class="text-xs w-20 shrink-0 {s.empty ? 'text-hint' : 'text-emphasis'}">{s.label}</span>
+			<span class="text-xs w-12 shrink-0 tabular-nums {s.empty ? 'text-hint' : 'text-secondary'}"
+				>{s.count ?? ''}</span
+			>
+			<span class="text-2xs text-hint truncate min-w-0">
+				{s.names.length ? s.names.join(', ') : s.emptyText}
+			</span>
+		</button>
+		{#if open[s.id]}
+			<div class="pl-10 pr-2 pt-1 pb-3" transition:slide|local={{ duration: 150 }}>
+				<ContextSectionDetail {ctx} section={s.id} {actions} {toggleBlockedReason} />
+			</div>
+		{/if}
+	{/each}
+</div>
diff --git a/frontend/src/lib/components/copilot/chat/contextSummary/contextSummary.ts b/frontend/src/lib/components/copilot/chat/contextSummary/contextSummary.ts
new file mode 100644
index 0000000000..7cba3a5966
--- /dev/null
+++ b/frontend/src/lib/components/copilot/chat/contextSummary/contextSummary.ts
@@ -0,0 +1,116 @@
+export type ContextSectionId = 'tools' | 'skills' | 'instructions' | 'mcp'
+
+export type ContextTool = { name: string; description: string; readOnly: boolean }
+export type ContextSkill = { path: string; name: string; description: string; enabled: boolean }
+export type ContextMcpServer = {
+	path: string
+	name: string
+	description?: string
+	enabled: boolean
+}
+/** What a session's agent is given before the first message. `tools` is every tool
+ * definition the chat loop sends, the MCP bridge tools included — a server's own tools
+ * are discovered at call time and are not part of the prompt. */
+export type AgentContext = {
+	workspace: string
+	tools: ContextTool[]
+	skills: ContextSkill[]
+	mcpServers: ContextMcpServer[]
+	instructions: { workspace?: string; user?: string }
+}
+
+export type ContextSummaryActions = {
+	onToggleSkill: (path: string, enabled: boolean) => void
+	onToggleMcp: (path: string, enabled: boolean) => void
+	/** Opens the assistant settings modal on that section. */
+	onManage: (section: ContextSectionId) => void
+}
+
+export type ContextSectionSummary = {
+	id: ContextSectionId
+	label: string
+	/** Undefined for Instructions, which has no count. */
+	count: string | undefined
+	/** Names of what reaches the agent, in display order. */
+	names: string[]
+	empty: boolean
+	/** Shown when the section is empty, or when everything in it is turned off. */
+	emptyText: string
+	/** Label of the action that opens the settings modal on an empty section. */
+	emptyAction?: string
+}
+
+export const CONTEXT_SECTION_ORDER: ContextSectionId[] = [
+	'tools',
+	'skills',
+	'instructions',
+	'mcp'
+]
+
+function partCount(on: number, total: number): string {
+	return on === total ? `${total}` : `${on} of ${total}`
+}
+
+export function summarizeContextSection(
+	ctx: AgentContext,
+	id: ContextSectionId
+): ContextSectionSummary {
+	switch (id) {
+		case 'tools': {
+			const read = ctx.tools.filter((t) => t.readOnly).length
+			return {
+				id,
+				label: 'Tools',
+				count: `${ctx.tools.length}`,
+				// The split rather than the names: which tools can change something is the one
+				// thing worth reading off a collapsed row.
+				names: ctx.tools.length ? [`${read} read`, `${ctx.tools.length - read} write`] : [],
+				empty: ctx.tools.length === 0,
+				emptyText: 'No tools'
+			}
+		}
+		case 'skills': {
+			const on = ctx.skills.filter((s) => s.enabled)
+			return {
+				id,
+				label: 'Skills',
+				count: ctx.skills.length ? partCount(on.length, ctx.skills.length) : '0',
+				names: on.map((s) => s.name),
+				empty: ctx.skills.length === 0,
+				emptyText: ctx.skills.length ? 'All turned off' : 'No skills',
+				emptyAction: 'Add skill'
+			}
+		}
+		case 'instructions': {
+			const names = [
+				ctx.instructions.workspace?.trim() ? 'workspace' : undefined,
+				ctx.instructions.user?.trim() ? 'personal' : undefined
+			].filter((n) => n !== undefined)
+			return {
+				id,
+				label: 'Instructions',
+				count: undefined,
+				names,
+				empty: names.length === 0,
+				emptyText: 'No instructions',
+				emptyAction: 'Write instructions'
+			}
+		}
+		case 'mcp': {
+			const on = ctx.mcpServers.filter((s) => s.enabled)
+			return {
+				id,
+				label: 'MCP',
+				count: ctx.mcpServers.length ? partCount(on.length, ctx.mcpServers.length) : '0',
+				names: on.map((s) => s.name),
+				empty: ctx.mcpServers.length === 0,
+				emptyText: ctx.mcpServers.length ? 'All turned off' : 'No servers',
+				emptyAction: 'Connect'
+			}
+		}
+	}
+}
+
+export function summarizeContext(ctx: AgentContext): ContextSectionSummary[] {
+	return CONTEXT_SECTION_ORDER.map((id) => summarizeContextSection(ctx, id))
+}
diff --git a/frontend/src/lib/components/copilot/chat/contextSummary/sectionIcons.ts b/frontend/src/lib/components/copilot/chat/contextSummary/sectionIcons.ts
new file mode 100644
index 0000000000..6c767d8ce2
--- /dev/null
+++ b/frontend/src/lib/components/copilot/chat/contextSummary/sectionIcons.ts
@@ -0,0 +1,10 @@
+import { BookOpen, Boxes, Plug, ScrollText } from 'lucide-svelte'
+import type { ContextSectionId } from './contextSummary'
+
+/** The settings modal's section icons, so both surfaces read as the same thing. */
+export const CONTEXT_SECTION_ICONS = {
+	tools: Boxes,
+	skills: BookOpen,
+	instructions: ScrollText,
+	mcp: Plug
+} satisfies Record<ContextSectionId, unknown>
diff --git a/frontend/src/routes/(root)/(logged)/dev/agent-context/+page.svelte b/frontend/src/routes/(root)/(logged)/dev/agent-context/+page.svelte
new file mode 100644
index 0000000000..7218591536
--- /dev/null
+++ b/frontend/src/routes/(root)/(logged)/dev/agent-context/+page.svelte
@@ -0,0 +1,77 @@
+<script lang="ts">
+	// Dev-only design page for the context summary an empty session chat shows. Not
+	// linked anywhere; open at /dev/agent-context. Mock data only, so the shapes a real
+	// workspace rarely has (nothing configured, a dozen skills) can be looked at.
+	import ToggleButtonGroup from '$lib/components/common/toggleButton-v2/ToggleButtonGroup.svelte'
+	import ToggleButton from '$lib/components/common/toggleButton-v2/ToggleButton.svelte'
+	import ContextSummaryRows from '$lib/components/copilot/chat/contextSummary/ContextSummaryRows.svelte'
+	import type {
+		AgentContext,
+		ContextSummaryActions
+	} from '$lib/components/copilot/chat/contextSummary/contextSummary'
+	import { sendUserToast } from '$lib/toast'
+	import { ArrowUp, Paperclip } from 'lucide-svelte'
+	import { MOCK_CONTEXTS } from './mockContexts'
+
+	let scenario = $state(MOCK_CONTEXTS[1].id)
+	let ctx = $state<AgentContext>(structuredClone(MOCK_CONTEXTS[1].ctx))
+
+	function selectScenario(id: string) {
+		const found = MOCK_CONTEXTS.find((m) => m.id === id)
+		if (found) ctx = structuredClone(found.ctx)
+	}
+
+	const actions: ContextSummaryActions = {
+		onToggleSkill: (path, enabled) => {
+			const skill = ctx.skills.find((s) => s.path === path)
+			if (skill) skill.enabled = enabled
+		},
+		onToggleMcp: (path, enabled) => {
+			const server = ctx.mcpServers.find((s) => s.path === path)
+			if (server) server.enabled = enabled
+		},
+		onManage: (section) => sendUserToast(`Would open assistant settings on "${section}"`)
+	}
+</script>
+
+{#if import.meta.env.DEV}
+	<div class="h-full overflow-auto p-6 bg-surface">
+		<div class="max-w-[720px] mx-auto flex flex-col gap-4">
+			<div class="flex flex-col gap-1">
+				<h1 class="text-lg font-semibold text-emphasis">Agent context summary</h1>
+				<p class="text-xs text-secondary">
+					Dev-only mock of what an empty session chat shows about its agent's context.
+				</p>
+			</div>
+			<ToggleButtonGroup bind:selected={scenario} onSelected={selectScenario} noWFull>
+				{#snippet children({ item })}
+					{#each MOCK_CONTEXTS as m (m.id)}
+						<ToggleButton value={m.id} label={m.label} {item} small />
+					{/each}
+				{/snippet}
+			</ToggleButtonGroup>
+
+			<div
+				class="h-[560px] rounded-md border border-light bg-surface-primary flex flex-col overflow-hidden"
+			>
+				<div class="px-4 py-2 text-sm font-semibold text-hint shrink-0">Untitled session</div>
+				<!-- Auto margins rather than justify-*: justify clips content taller than the
+				     scroller. -->
+				<div class="flex-1 min-h-0 overflow-y-auto px-4 flex flex-col">
+					<div class="w-full max-w-xl mx-auto py-2 my-auto">
+						<ContextSummaryRows {ctx} {actions} />
+					</div>
+				</div>
+				<div class="px-4 pb-3 pt-1 shrink-0">
+					<div
+						class="max-w-xl mx-auto rounded-md border border-light bg-surface-input px-3 py-2 flex items-center gap-2"
+					>
+						<span class="text-xs text-hint grow">Ask anything…</span>
+						<Paperclip size={14} class="text-hint" />
+						<ArrowUp size={14} class="text-hint" />
+					</div>
+				</div>
+			</div>
+		</div>
+	</div>
+{/if}
diff --git a/frontend/src/routes/(root)/(logged)/dev/agent-context/mockContexts.ts b/frontend/src/routes/(root)/(logged)/dev/agent-context/mockContexts.ts
new file mode 100644
index 0000000000..2ad6d56a0f
--- /dev/null
+++ b/frontend/src/routes/(root)/(logged)/dev/agent-context/mockContexts.ts
@@ -0,0 +1,187 @@
+import type {
+	AgentContext,
+	ContextTool
+} from '$lib/components/copilot/chat/contextSummary/contextSummary'
+
+const BUILTIN_TOOL_NAMES = [
+	'askUserQuestion',
+	'cancel_job',
+	'close_page',
+	'create_artifact',
+	'create_folder',
+	'delete_workspace_item',
+	'deploy_workspace_item',
+	'diff',
+	'discard_local_draft',
+	'edit_script',
+	'get_instructions',
+	'get_preview_status',
+	'get_run',
+	'get_schedule_schema',
+	'get_trigger_schema',
+	'list_artifacts',
+	'list_runs',
+	'list_workers',
+	'list_workspace_items',
+	'open_page',
+	'open_preview',
+	'patch_flow_json',
+	'read_artifact',
+	'read_dom',
+	'read_flow_module_code',
+	'read_skill',
+	'read_workspace_item',
+	'rebase_draft',
+	'run_flow',
+	'run_script',
+	'search_dom',
+	'search_resource_types',
+	'set_flow_module_code',
+	'take_screenshot',
+	'test_run_flow',
+	'test_run_script',
+	'test_run_step',
+	'update_user_instructions',
+	'write_resource',
+	'write_schedule',
+	'write_trigger',
+	'write_variable'
+]
+
+// Read vs write the way the real summary decides it: a tool that only reads is the one
+// plan mode admits.
+const WRITE_PREFIXES = ['write_', 'delete_', 'deploy_', 'patch_', 'init_', 'test_run_', 'run_']
+
+function tools(names: string[]): ContextTool[] {
+	return names.map((name) => ({
+		name,
+		description: `Mock description of ${name}.`,
+		readOnly: !WRITE_PREFIXES.some((p) => name.startsWith(p))
+	}))
+}
+
+const empty: AgentContext = {
+	workspace: 'admins',
+	tools: tools(BUILTIN_TOOL_NAMES.slice(0, 38)),
+	skills: [],
+	mcpServers: [],
+	instructions: {}
+}
+
+const typical: AgentContext = {
+	workspace: 'acme',
+	tools: tools(BUILTIN_TOOL_NAMES.slice(0, 38)),
+	skills: [
+		{
+			path: 'f/ai/sql_style',
+			name: 'sql_style',
+			description: 'How we write SQL against the warehouse',
+			enabled: true
+		},
+		{
+			path: 'f/ai/pr_conventions',
+			name: 'pr_conventions',
+			description: 'Branch naming and PR description format',
+			enabled: false
+		},
+		{
+			path: 'f/ai/deploy_checklist',
+			name: 'deploy_checklist',
+			description: 'Checks to run before deploying a flow to prod',
+			enabled: true
+		}
+	],
+	mcpServers: [
+		{
+			path: 'u/admin/linear',
+			name: 'Linear',
+			enabled: true
+		},
+		{
+			path: 'u/admin/notion',
+			name: 'Notion',
+			enabled: false
+		}
+	],
+	instructions: {
+		workspace:
+			'Scripts go under f/<team>/. Always use the postgres resource f/data/warehouse for analytics queries.',
+		user: 'Answer briefly. Prefer Python over TypeScript.'
+	}
+}
+
+const heavy: AgentContext = {
+	workspace: 'platform-prod',
+	tools: tools([
+		...BUILTIN_TOOL_NAMES,
+		'write_app_file',
+		'read_app_file',
+		'patch_app_file',
+		'delete_app_file',
+		'init_app',
+		'search_app',
+		'list_app_runs',
+		'get_app_runtime_logs',
+		'write_app_runnable',
+		'delete_app_runnable',
+		'test_run_app_runnable',
+		'update_artifact',
+		'audit_logs',
+		'workspace_settings',
+		'resources',
+		'variables',
+		'schedules',
+		'triggers'
+	]),
+	skills: Array.from({ length: 12 }, (_, i) => ({
+		path: `f/ai/skill_${i + 1}`,
+		name: [
+			'sql_style',
+			'pr_conventions',
+			'deploy_checklist',
+			'incident_runbook',
+			'naming_rules',
+			'python_deps',
+			'retry_policy',
+			'slack_alerts',
+			'datatable_migrations',
+			'hub_usage',
+			'secrets_handling',
+			'flow_patterns'
+		][i],
+		description: 'Mock skill description that is long enough to be truncated in a narrow column',
+		enabled: i % 4 !== 3
+	})),
+	mcpServers: [
+		{
+			path: 'f/mcp/linear',
+			name: 'Linear',
+			enabled: true
+		},
+		{
+			path: 'f/mcp/github',
+			name: 'GitHub',
+			enabled: true
+		},
+		{ path: 'f/mcp/notion', name: 'Notion', enabled: false },
+		{ path: 'f/mcp/sentry', name: 'Sentry', enabled: true },
+		{ path: 'f/mcp/datadog', name: 'Datadog', enabled: false }
+	],
+	instructions: {
+		workspace: [
+			'This is the production platform workspace.',
+			'Never deploy directly: stage every change in a fork and ask for review.',
+			'Scripts go under f/<team>/, one folder per team.',
+			'Use f/data/warehouse for analytics and f/data/app_db for application data.',
+			'Every flow must set an error handler pointing to f/ops/alert_oncall.',
+			'Schedules run in UTC.'
+		].join('\n'),
+		user: 'Answer briefly.\nPrefer Python.\nWhen unsure about a resource, ask before creating one.\nI am on the data team.'
+	}
+}
+
+export const MOCK_CONTEXTS: { id: string; label: string; ctx: AgentContext }[] = [
+	{ id: 'empty', label: 'Fresh workspace', ctx: empty },
+	{ id: 'typical', label: 'Typical', ctx: typical },
+	{ id: 'heavy', label: 'Heavy', ctx: heavy }
+]