Match chat sessions to sites by site id instead of path

apps/studio/src/ipc-handlers.ts

@@ -28,6 +28,7 @@ import {
 	listHydratedAiSessions,
 	loadHydratedAiSession,
 } from '@studio/common/ai/sessions/manage';
+import { findAiSessionOwnerSite } from '@studio/common/ai/sessions/owner-site';
 import {
 	deleteAiSessionPlacement,
 	readAiSessionPlacement,
@@ -324,11 +325,8 @@ async function reconcileSessionEnvironmentBeforeRun( sessionId: string ): Promis
 	if ( summary.activeEnvironment !== 'live' ) {
 		return;
 	}
-	if ( ! summary.ownerSitePath ) {
-		return;
-	}
-
-	const ownerServer = SiteServer.getByPath( summary.ownerSitePath );
+	const ownerSite = findAiSessionOwnerSite( SiteServer.getAllDetails(), summary );
+	const ownerServer = ownerSite ? SiteServer.get( ownerSite.id ) : undefined;
 	if ( ! ownerServer ) {
 		return;
 	}
@@ -345,7 +343,7 @@ async function reconcileSessionEnvironmentBeforeRun( sessionId: string ): Promis
 	// CLI's replay sees Local on the next turn.
 	await appendStudioEntry( root, sessionId, 'studio.site_selected', {
 		siteName: ownerServer.details.name,
-		sitePath: summary.ownerSitePath,
+		sitePath: ownerServer.details.path,
 	} );
 }
 
@@ -442,14 +440,17 @@ export async function setSessionEnvironment(
 ): Promise< SetSessionEnvironmentResult > {
 	const { summary } = await loadHydratedAiSession( getAiSessionsRootDirectory(), sessionId );
 
-	if ( ! summary.ownerSitePath || ! summary.ownerSiteName ) {
+	if ( ! summary.ownerSiteId && ! summary.ownerSitePath ) {
 		throw new Error( 'Cannot change environment: session has no owner site' );
 	}
 
-	const ownerServer = SiteServer.getByPath( summary.ownerSitePath );
+	const ownerSite = findAiSessionOwnerSite( SiteServer.getAllDetails(), summary );
+	const ownerServer = ownerSite ? SiteServer.get( ownerSite.id ) : undefined;
 	if ( ! ownerServer ) {
 		throw new Error(
-			`Cannot change environment: owner site is no longer available (${ summary.ownerSitePath })`
+			`Cannot change environment: owner site is no longer available (${
+				summary.ownerSiteId ?? summary.ownerSitePath
+			})`
 		);
 	}
 
@@ -465,9 +466,9 @@ export async function setSessionEnvironment(
 
 		await appendStudioEntry( getAiSessionsRootDirectory(), sessionId, 'studio.site_selected', {
 			siteName: liveSite.name,
-			// Keep the desktop placement path on remote picks too, so live/local
+			// Keep the local owner's path on remote picks too, so live/local
 			// environment flips still resolve against the same local site.
-			sitePath: summary.ownerSitePath,
+			sitePath: ownerServer.details.path,
 			remote: true,
 			url: liveSite.url,
 			wpcomSiteId: liveSite.id,

apps/ui/src/components/site-list/index.test.tsx

@@ -1,4 +1,4 @@
-import { fireEvent, render, screen } from '@testing-library/react';
+import { fireEvent, render, screen, within } from '@testing-library/react';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { useConnector } from '@/data/core';
 import { useIsSessionRunning, useSessionHasPendingQuestion } from '@/data/queries/use-agent-run';
@@ -16,7 +16,7 @@ import {
 } from '@/data/queries/use-sites';
 import { useUserPreferences } from '@/data/queries/use-user-preferences';
 import { SiteList } from './index';
-import type { SiteDetails } from '@/data/core';
+import type { AiSessionSummary, SiteDetails } from '@/data/core';
 import type { ReactNode } from 'react';
 
 vi.mock( '@tanstack/react-router', () => ( {
@@ -145,8 +145,65 @@ describe( 'SiteList', () => {
 		expect( actionGlyph?.querySelector( 'rect' ) ).toHaveAttribute( 'width', '8' );
 		expect( actionGlyph?.querySelector( 'path' ) ).not.toBeInTheDocument();
 	} );
+
+	it( 'groups sessions by owner site id, falling back to path for legacy sessions', () => {
+		useSitesMock.mockReturnValue( {
+			data: [
+				createSite( { id: 'site-a', name: 'Site A', path: '/sites/site-a' } ),
+				createSite( { id: 'site-b', name: 'Site B', path: '/sites/site-b' } ),
+			],
+			isLoading: false,
+		} );
+		useSessionsMock.mockReturnValue( {
+			data: [
+				// A stale path must lose to the site id.
+				createSession( {
+					id: 'by-id',
+					firstPrompt: 'Matched by id',
+					ownerSiteId: 'site-b',
+					ownerSitePath: '/sites/site-a',
+				} ),
+				createSession( {
+					id: 'legacy',
+					firstPrompt: 'Matched by path',
+					ownerSitePath: '/sites/site-a',
+				} ),
+				// A deleted site's id must not fall back to a path that now
+				// belongs to another site.
+				createSession( {
+					id: 'orphan',
+					firstPrompt: 'Dead site id',
+					ownerSiteId: 'deleted-site',
+					ownerSitePath: '/sites/site-a',
+				} ),
+			],
+			isLoading: false,
+		} );
+
+		render( <SiteList /> );
+
+		const siteA = screen.getByText( 'Site A' ).closest( 'section' )!;
+		const siteB = screen.getByText( 'Site B' ).closest( 'section' )!;
+		const unassigned = screen.getByText( 'Unassigned' ).closest( 'section' )!;
+
+		expect( within( siteB ).getByText( 'Matched by id' ) ).toBeInTheDocument();
+		expect( within( siteA ).getByText( 'Matched by path' ) ).toBeInTheDocument();
+		expect( within( unassigned ).getByText( 'Dead site id' ) ).toBeInTheDocument();
+	} );
 } );
 
+function createSession( overrides: Partial< AiSessionSummary > = {} ): AiSessionSummary {
+	return {
+		id: 'session-1',
+		filePath: '/sessions/session-1.jsonl',
+		createdAt: '2026-07-01T00:00:00.000Z',
+		updatedAt: '2026-07-01T00:00:00.000Z',
+		activeEnvironment: 'local',
+		eventCount: 1,
+		...overrides,
+	};
+}
+
 function createSite( overrides: Partial< SiteDetails > = {} ): SiteDetails {
 	return {
 		id: 'site-1',

apps/ui/src/components/site-list/index.tsx

@@ -1,3 +1,4 @@
+import { findAiSessionOwnerSite } from '@studio/common/ai/sessions/owner-site';
 import { Link, useNavigate, useParams } from '@tanstack/react-router';
 import { __, sprintf } from '@wordpress/i18n';
 import {
@@ -50,8 +51,7 @@ function groupSessionsByOwner(
 	sites: SiteDetails[] | undefined,
 	sessions: AiSessionSummary[] | undefined
 ): SiteGroup[] {
-	const knownSitePaths = new Set( ( sites ?? [] ).map( ( site ) => site.path ) );
-	const sessionsByPath = new Map< string, AiSessionSummary[] >();
+	const sessionsBySiteId = new Map< string, AiSessionSummary[] >();
 	const unassigned: AiSessionSummary[] = [];
 
 	for ( const session of sessions ?? [] ) {
@@ -61,24 +61,25 @@ function groupSessionsByOwner(
 		if ( session.archived ) {
 			continue;
 		}
-		if ( ! session.ownerSitePath || ! knownSitePaths.has( session.ownerSitePath ) ) {
+		const ownerSite = findAiSessionOwnerSite( sites, session );
+		if ( ! ownerSite ) {
 			unassigned.push( session );
 			continue;
 		}
 
-		const existing = sessionsByPath.get( session.ownerSitePath );
+		const existing = sessionsBySiteId.get( ownerSite.id );
 		if ( existing ) {
 			existing.push( session );
 		} else {
-			sessionsByPath.set( session.ownerSitePath, [ session ] );
+			sessionsBySiteId.set( ownerSite.id, [ session ] );
 		}
 	}
 
 	const groups: SiteGroup[] = ( sites ?? [] ).map( ( site ) => ( {
 		key: site.id,
 		site,
 		label: site.name,
-		sessions: sessionsByPath.get( site.path ) ?? [],
+		sessions: sessionsBySiteId.get( site.id ) ?? [],
 	} ) );
 
 	// Sort site-groups by the newest session's updatedAt so the most recently

apps/ui/src/ui-classic/components/session-view/index.tsx

@@ -1,4 +1,5 @@
 import { resolveSessionModel } from '@studio/common/ai/models';
+import { findAiSessionOwnerSite } from '@studio/common/ai/sessions/owner-site';
 import { useNavigate } from '@tanstack/react-router';
 import { __ } from '@wordpress/i18n';
 import { clsx } from 'clsx';
@@ -31,7 +32,7 @@ function SessionHeader( { summary }: SessionHeaderProps ) {
 	const sidebarCollapsed = useSidebarCollapsed();
 	const reserveTrafficLightSpace = useTrafficLightSpace();
 	const { data: sites } = useSites();
-	const site = sites?.find( ( candidate ) => candidate.path === summary.ownerSitePath );
+	const site = findAiSessionOwnerSite( sites, summary );
 	const effectiveEnvironment = useSessionEffectiveEnvironment( summary, site?.id );
 	if ( ! siteName ) {
 		return null;
@@ -152,10 +153,7 @@ function SessionViewContent( { sessionId }: { sessionId: string } ) {
 	const navigate = useNavigate();
 	const { data, isLoading, error } = useSession( sessionId );
 	const { data: sites } = useSites();
-	const ownerSitePath = data?.summary.ownerSitePath;
-	const ownerSite = ownerSitePath
-		? sites?.find( ( candidate ) => candidate.path === ownerSitePath )
-		: undefined;
+	const ownerSite = findAiSessionOwnerSite( sites, data?.summary );
 	const effectiveEnvironment = useSessionEffectiveEnvironment( data?.summary, ownerSite?.id );
 	const {
 		isRunning,

apps/ui/src/ui-classic/router/layout-dashboard/index.tsx

@@ -1,3 +1,4 @@
+import { findAiSessionOwnerSite } from '@studio/common/ai/sessions/owner-site';
 import { createRoute, Outlet, useRouterState } from '@tanstack/react-router';
 import { useCallback, useEffect, useState } from 'react';
 import {
@@ -52,10 +53,7 @@ function DashboardLayoutContent() {
 	const { data: sessionData } = useSession( sessionId );
 	const preview = useSessionPreviewUI();
 	const onAnnotationsDone = useSessionPreviewAnnotationsHandler();
-	const sessionOwnerSitePath = sessionData?.summary.ownerSitePath;
-	const sessionSite = sessionOwnerSitePath
-		? sites?.find( ( site ) => site.path === sessionOwnerSitePath )
-		: undefined;
+	const sessionSite = findAiSessionOwnerSite( sites, sessionData?.summary );
 	const effectiveEnvironment = useSessionEffectiveEnvironment(
 		sessionData?.summary,
 		sessionSite?.id

apps/ui/src/ui-classic/router/route-index/index.tsx

@@ -1,3 +1,4 @@
+import { aiSessionBelongsToSite } from '@studio/common/ai/sessions/owner-site';
 import { createRoute, redirect } from '@tanstack/react-router';
 import { SESSIONS_QUERY_KEY } from '@/data/queries/use-sessions';
 import { SITES_QUERY_KEY } from '@/data/queries/use-sites';
@@ -22,7 +23,7 @@ export const indexRoute = createRoute( {
 		} );
 		// Sessions arrive sorted newest-first, so the first session owned by
 		// the site is its most recently updated one.
-		const topSession = sessions.find( ( session ) => session.ownerSitePath === firstSite.path );
+		const topSession = sessions.find( ( session ) => aiSessionBelongsToSite( session, firstSite ) );
 		if ( topSession ) {
 			throw redirect( { to: '/sessions/$sessionId', params: { sessionId: topSession.id } } );
 		}

packages/common/ai/sessions/manage.ts

@@ -1,3 +1,4 @@
+import { aiSessionBelongsToSite } from '@studio/common/ai/sessions/owner-site';
 import {
 	hydrateAiSessionSummaryWithPlacement,
 	readAiSessionPlacement,
@@ -82,7 +83,11 @@ export async function createOrReuseAiSession(
 	if ( ! site ) {
 		const reusable = existing
 			.filter(
-				( session ) => ! session.ownerSitePath && ! session.firstPrompt && ! session.archived
+				( session ) =>
+					! session.ownerSiteId &&
+					! session.ownerSitePath &&
+					! session.firstPrompt &&
+					! session.archived
 			)
 			.sort( newestFirst )[ 0 ];
 		if ( reusable ) {
@@ -94,7 +99,7 @@ export async function createOrReuseAiSession(
 	const reusable = existing
 		.filter(
 			( session ) =>
-				session.ownerSitePath === site.path && ! session.firstPrompt && ! session.archived
+				! session.firstPrompt && ! session.archived && aiSessionBelongsToSite( session, site )
 		)
 		.sort( newestFirst )[ 0 ];
 	if ( reusable ) {

packages/common/ai/sessions/owner-site.ts

@@ -0,0 +1,25 @@
+import type { AiSessionSummary } from './types';
+
+type OwnerRef = Pick< AiSessionSummary, 'ownerSiteId' | 'ownerSitePath' >;
+
+// A session with an ownerSiteId never matches by path — a dead id must not
+// rebind to a new site created at the same folder. Path matching only covers
+// placements written before siteId existed.
+export function aiSessionBelongsToSite(
+	session: OwnerRef,
+	site: { id: string; path: string }
+): boolean {
+	return session.ownerSiteId
+		? session.ownerSiteId === site.id
+		: session.ownerSitePath === site.path;
+}
+
+export function findAiSessionOwnerSite< T extends { id: string; path: string } >(
+	sites: T[] | undefined,
+	session: OwnerRef | undefined
+): T | undefined {
+	if ( ! session ) {
+		return undefined;
+	}
+	return sites?.find( ( site ) => aiSessionBelongsToSite( session, site ) );
+}

packages/common/ai/sessions/placement.ts

@@ -62,9 +62,19 @@ export function hydrateAiSessionSummaryWithPlacement(
 	placement?: AiSessionSitePlacement
 ): AiSessionSummary {
 	if ( ! placement ) {
-		return { ...summary, ownerSitePath: undefined, ownerSiteName: undefined };
+		return {
+			...summary,
+			ownerSiteId: undefined,
+			ownerSitePath: undefined,
+			ownerSiteName: undefined,
+		};
 	}
-	return { ...summary, ownerSitePath: placement.sitePath, ownerSiteName: placement.siteName };
+	return {
+		...summary,
+		ownerSiteId: placement.siteId,
+		ownerSitePath: placement.sitePath,
+		ownerSiteName: placement.siteName,
+	};
 }
 
 // Extracts a created-site placement from a `chat.artifact` event, if the agent

packages/common/ai/sessions/summary.ts

@@ -130,6 +130,7 @@ export async function readAiSessionSummaryFromEntries(
 		updatedAt: updatedAt ?? createdAt ?? fallbackTimestamp,
 		firstPrompt,
 		assistantReplyPreview,
+		ownerSiteId: undefined,
 		ownerSitePath: undefined,
 		ownerSiteName: undefined,
 		selectedSiteName,

packages/common/ai/sessions/tests/create-session.test.ts

@@ -21,6 +21,7 @@ describe( 'createAiSession', () => {
 			site: { name: 'My Site', path: '/tmp/my-site' },
 		} );
 
+		expect( summary.ownerSiteId ).toBeUndefined();
 		expect( summary.ownerSitePath ).toBeUndefined();
 		expect( summary.ownerSiteName ).toBeUndefined();
 		expect( summary.selectedSiteName ).toBe( 'My Site' );