diff --git a/src/vs/workbench/contrib/chat/browser/aiCustomization/aiCustomizationManagementEditor.ts b/src/vs/workbench/contrib/chat/browser/aiCustomization/aiCustomizationManagementEditor.ts
index e002b0fcf3869a..ccd64a886427bf 100644
--- a/src/vs/workbench/contrib/chat/browser/aiCustomization/aiCustomizationManagementEditor.ts
+++ b/src/vs/workbench/contrib/chat/browser/aiCustomization/aiCustomizationManagementEditor.ts
@@ -1601,6 +1601,7 @@ export class AICustomizationManagementEditor extends EditorPane {
 		this.customizationsByMigrationCategory = candidatesByCategory;
 		this.customizationMigrationTargetFoldersByType = targetFoldersByType;
 		this.customizationMigrationResultsSettled = true;
+		this.reconcileMigrationActivity(candidatesByCategory);
 		this.reconcileCustomizationMigrationTargets();
 		this.refreshCustomizationMigrationUi();
 		if (this.viewMode === 'migration' && this.activeMigrationCategoryId !== undefined && !candidatesByCategory.has(this.activeMigrationCategoryId)) {
@@ -1666,6 +1667,47 @@ export class AICustomizationManagementEditor extends EditorPane {
 			: `file:${customization.storage}:${customization.uri.toString()}`;
 	}
 
+	private reconcileMigrationActivity(candidatesByCategory: ReadonlyMap<CustomizationMigrationCategoryId, readonly CustomizationMigrationCandidate[]>): void {
+		const candidatesByStorage = new Map<PromptsStorage, readonly CustomizationMigrationCandidate[]>();
+		for (const storage of [PromptsStorage.user, PromptsStorage.local]) {
+			candidatesByStorage.set(storage, [...candidatesByCategory.values()].flat().filter(candidate => this.getMigrationCandidateStorage(candidate) === storage));
+		}
+
+		for (const [storage, candidates] of candidatesByStorage) {
+			const candidateKeys = new Set(candidates.map(candidate => this.getMigrationActivityCandidateKey(candidate)));
+			const legacyCandidateKeys = new Set(candidates.map(candidate => this.getLegacyMigrationActivityKey(candidate)));
+			const state = this.getMigrationActivityState(storage);
+			let changed = false;
+			const activity = state.activity.flatMap(entry => {
+				const items = entry.items.filter(item => {
+					const reverted = item.operation !== 'copied' && (item.migrationKey
+						? candidateKeys.has(item.migrationKey)
+						: legacyCandidateKeys.has(JSON.stringify([item.label, item.sourceLabel])));
+					changed ||= reverted;
+					return !reverted;
+				});
+				return items.length ? [{ ...entry, items }] : [];
+			});
+			if (changed) {
+				this.storeMigrationActivityState(storage, { ...state, activity });
+			}
+		}
+	}
+
+	private getMigrationActivityCandidateKey(candidate: CustomizationMigrationCandidate): string {
+		return isMcpServerCustomizationMigrationCandidate(candidate)
+			? `mcp:${getMcpServerCustomizationMigrationCandidateKey(candidate)}`
+			: `file:${candidate.storage}:${getComparisonKey(candidate.uri)}`;
+	}
+
+	private getLegacyMigrationActivityKey(candidate: CustomizationMigrationCandidate): string {
+		const label = isMcpServerCustomizationMigrationCandidate(candidate)
+			? candidate.name
+			: candidate.name ?? basename(candidate.uri);
+		const sourceUri = isMcpServerCustomizationMigrationCandidate(candidate) ? candidate.sourceUri : candidate.uri;
+		return JSON.stringify([label, this.labelService.getUriLabel(sourceUri)]);
+	}
+
 	private isCustomizationSelectedForMigration(customization: CustomizationMigrationCandidate): boolean {
 		if (isMcpServerCustomizationMigrationCandidate(customization)) {
 			return this.selectedMcpServerMigrationItems.has(getMcpServerCustomizationMigrationCandidateKey(customization));
@@ -1814,6 +1856,7 @@ export class AICustomizationManagementEditor extends EditorPane {
 						sourceLabel: this.labelService.getUriLabel(source.uri),
 						targetLabel: this.labelService.getUriLabel(target.uri),
 						operation: file.type === PromptsType.prompt ? 'converted' as const : deleteOriginalFiles ? 'moved' as const : 'copied' as const,
+						migrationKey: this.getMigrationActivityCandidateKey(file),
 					}] : [];
 				});
 				this.recordMigrationActivity(category, context, items);
@@ -1886,6 +1929,7 @@ export class AICustomizationManagementEditor extends EditorPane {
 				sourceLabel: this.labelService.getUriLabel(server.sourceUri),
 				targetLabel: this.labelService.getUriLabel(server.targetUri),
 				operation: 'server',
+				migrationKey: this.getMigrationActivityCandidateKey(server),
 			})));
 		}
 		await this.refreshCustomizationMigrationInfo();
diff --git a/src/vs/workbench/contrib/chat/browser/aiCustomization/customizationMigrationDashboard.ts b/src/vs/workbench/contrib/chat/browser/aiCustomization/customizationMigrationDashboard.ts
index 53e51597f24f4f..c255fc9a47b173 100644
--- a/src/vs/workbench/contrib/chat/browser/aiCustomization/customizationMigrationDashboard.ts
+++ b/src/vs/workbench/contrib/chat/browser/aiCustomization/customizationMigrationDashboard.ts
@@ -56,6 +56,7 @@ export interface ICustomizationMigrationDashboardActivity {
 		readonly sourceLabel: string;
 		readonly targetLabel: string;
 		readonly operation: 'converted' | 'moved' | 'copied' | 'server';
+		readonly migrationKey?: string;
 	}[];
 }
 
diff --git a/src/vs/workbench/contrib/chat/test/browser/aiCustomization/aiCustomizationManagementEditor.test.ts b/src/vs/workbench/contrib/chat/test/browser/aiCustomization/aiCustomizationManagementEditor.test.ts
index cec0180a12e76b..cf1cc96849d3a7 100644
--- a/src/vs/workbench/contrib/chat/test/browser/aiCustomization/aiCustomizationManagementEditor.test.ts
+++ b/src/vs/workbench/contrib/chat/test/browser/aiCustomization/aiCustomizationManagementEditor.test.ts
@@ -1603,7 +1603,13 @@ suite('aiCustomizationManagementEditor', () => {
 				categoryLabel: 'MCP Servers',
 				scopeLabel: 'vscode',
 				storage: PromptsStorage.local,
-				items: [{ label: 'server', sourceLabel: '/workspace/.vscode/mcp.json', targetLabel: '/workspace/.mcp.json', operation: 'server' }],
+				items: [{
+					label: 'server',
+					sourceLabel: '/workspace/.vscode/mcp.json',
+					targetLabel: '/workspace/.mcp.json',
+					operation: 'server',
+					migrationKey: 'mcp:["mcp.config.ws0.server","server","file:///workspace/.vscode/mcp.json","file:///workspace/.mcp.json"]',
+				}],
 			}],
 		});
 		editor.editorPreviewDisposables.dispose();
@@ -1748,6 +1754,64 @@ suite('aiCustomizationManagementEditor', () => {
 		editor.editorPreviewDisposables.dispose();
 	});
 
+	test('removes reverted migration activity while preserving copied activity', () => {
+		const editor = createTestEditor(undefined, createConfigurationServiceStub({
+			[ChatConfiguration.ChatCustomizationsPromptMigrationEnabled]: true,
+		}));
+		const category = getCustomizationMigrationCategory(CustomizationMigrationCategoryId.PromptFiles);
+		const context = editor.getMigrationActivityContext(PromptsStorage.local);
+		const revertedPrompt: MigratableConfiguration = {
+			uri: URI.file('/workspace/.github/prompts/review.prompt.md'),
+			name: 'review.prompt.md',
+			storage: PromptsStorage.local,
+			type: PromptsType.prompt,
+			source: PromptFileSource.GitHubWorkspace,
+		};
+		const legacyPrompt: MigratableConfiguration = {
+			...revertedPrompt,
+			uri: URI.file('/workspace/.github/prompts/legacy.prompt.md'),
+			name: 'legacy.prompt.md',
+		};
+		editor.recordMigrationActivity(category, context, [{
+			label: 'review.prompt.md',
+			sourceLabel: '/workspace/.github/prompts/review.prompt.md',
+			targetLabel: '/workspace/.github/skills/review/SKILL.md',
+			operation: 'converted',
+			migrationKey: `file:${PromptsStorage.local}:${revertedPrompt.uri.toString()}`,
+		}, {
+			label: 'legacy.prompt.md',
+			sourceLabel: '/workspace/.github/prompts/legacy.prompt.md',
+			targetLabel: '/workspace/.github/skills/legacy/SKILL.md',
+			operation: 'converted',
+		}, {
+			label: 'review.prompt.md',
+			sourceLabel: '/workspace/.github/prompts/review.prompt.md',
+			targetLabel: '/workspace/.agents/prompts/review.prompt.md',
+			operation: 'copied',
+			migrationKey: `file:${PromptsStorage.local}:${revertedPrompt.uri.toString()}`,
+		}]);
+
+		editor.setCustomizationsToMigrate(new Map([[category.id, [revertedPrompt, legacyPrompt]]]), new Map());
+
+		const state = editor.getMigrationActivityState(PromptsStorage.local);
+		assert.deepStrictEqual({
+			activity: state.activity.map(entry => entry.items),
+			skipped: state.skipped,
+			started: state.started,
+		}, {
+			activity: [[{
+				label: 'review.prompt.md',
+				sourceLabel: '/workspace/.github/prompts/review.prompt.md',
+				targetLabel: '/workspace/.agents/prompts/review.prompt.md',
+				operation: 'copied',
+				migrationKey: `file:${PromptsStorage.local}:${revertedPrompt.uri.toString()}`,
+			}]],
+			skipped: false,
+			started: true,
+		});
+		editor.editorPreviewDisposables.dispose();
+	});
+
 	test('persists file migration activity newest first for the initiating profile', () => {
 		const editor = createTestEditor();
 		const category = getCustomizationMigrationCategory(CustomizationMigrationCategoryId.PromptFiles);