feat: add archiving flows for sessions and workspaces

Users previously had an all-or-nothing choice for completed sessions: either keep them in the active
sidebar or permanently delete them. That made long-lived usage brittle because valuable history
stayed in the way unless users destroyed it. This change introduces archiving as a first-class
lifecycle so completed work can be hidden without losing transcript history, workspace context,
or restoreability.

The backend now persists session archive state and excludes archived rows from active session
queries by default. Dedicated archive queries and routes make archived sessions and archived
workspaces addressable on their own, which is necessary once hidden data can no longer be rebuilt
from the active project list. Hard-delete behavior still cleans up transcript files so destructive
deletes remain truly destructive.

The frontend now mirrors that lifecycle in the sidebar. Delete flows distinguish between archive
and permanent delete, archived sessions can be restored, archived workspaces appear beside
standalone archived sessions, and archived project sessions open with the correct workspace context
instead of routing to a session URL that leaves the main view empty. Follow-up archive UI polish
keeps the status affordances explicit without competing with workspace names.

server/modules/database/migrations.ts

@@ -257,8 +257,10 @@ const rebuildSessionsTableWithProjectSchema = (db: Database): void => {
 
   if (!shouldRebuild) {
     addColumnToTableIfNotExists(db, 'sessions', columnNames, 'jsonl_path', 'TEXT');
+    addColumnToTableIfNotExists(db, 'sessions', columnNames, 'isArchived', 'BOOLEAN DEFAULT 0');
     addColumnToTableIfNotExists(db, 'sessions', columnNames, 'created_at', 'DATETIME');
     addColumnToTableIfNotExists(db, 'sessions', columnNames, 'updated_at', 'DATETIME');
+    db.exec('UPDATE sessions SET isArchived = COALESCE(isArchived, 0)');
     db.exec('UPDATE sessions SET created_at = COALESCE(created_at, CURRENT_TIMESTAMP)');
     db.exec('UPDATE sessions SET updated_at = COALESCE(updated_at, CURRENT_TIMESTAMP)');
     return;
@@ -284,6 +286,10 @@ const rebuildSessionsTableWithProjectSchema = (db: Database): void => {
     ? 'jsonl_path'
     : 'NULL';
 
+  const isArchivedExpression = columnNames.includes('isArchived')
+    ? 'COALESCE(isArchived, 0)'
+    : '0';
+
   const createdAtExpression = columnNames.includes('created_at')
     ? 'COALESCE(created_at, CURRENT_TIMESTAMP)'
     : 'CURRENT_TIMESTAMP';
@@ -303,6 +309,7 @@ const rebuildSessionsTableWithProjectSchema = (db: Database): void => {
         custom_name TEXT,
         project_path TEXT,
         jsonl_path TEXT,
+        isArchived BOOLEAN DEFAULT 0,
         created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
         updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
         PRIMARY KEY (session_id),
@@ -319,6 +326,7 @@ const rebuildSessionsTableWithProjectSchema = (db: Database): void => {
           ${customNameExpression} AS custom_name,
           ${projectPathExpression} AS project_path,
           ${jsonlPathExpression} AS jsonl_path,
+          ${isArchivedExpression} AS isArchived,
           ${createdAtExpression} AS created_at,
           ${updatedAtExpression} AS updated_at,
           rowid AS source_rowid
@@ -332,6 +340,7 @@ const rebuildSessionsTableWithProjectSchema = (db: Database): void => {
           custom_name,
           project_path,
           jsonl_path,
+          isArchived,
           created_at,
           updated_at,
           ROW_NUMBER() OVER (
@@ -346,6 +355,7 @@ const rebuildSessionsTableWithProjectSchema = (db: Database): void => {
         custom_name,
         project_path,
         jsonl_path,
+        isArchived,
         created_at,
         updated_at
       )
@@ -355,6 +365,7 @@ const rebuildSessionsTableWithProjectSchema = (db: Database): void => {
         custom_name,
         project_path,
         jsonl_path,
+        isArchived,
         created_at,
         updated_at
       FROM ranked_rows
@@ -421,6 +432,7 @@ export const runMigrations = (db: Database) => {
 
     db.exec('CREATE INDEX IF NOT EXISTS idx_session_ids_lookup ON sessions(session_id)');
     db.exec('CREATE INDEX IF NOT EXISTS idx_sessions_project_path ON sessions(project_path)');
+    db.exec('CREATE INDEX IF NOT EXISTS idx_sessions_is_archived ON sessions(isArchived)');
     db.exec('CREATE INDEX IF NOT EXISTS idx_projects_is_starred ON projects(isStarred)');
     db.exec('CREATE INDEX IF NOT EXISTS idx_projects_is_archived ON projects(isArchived)');
 

server/modules/database/repositories/projects.db.ts

@@ -95,6 +95,19 @@ export const projectsDb = {
         `).all() as ProjectRepositoryRow[];
     },
 
+    /**
+     * Archived rows are queried separately so archive-focused UIs can present
+     * hidden workspaces without reintroducing them into the active sidebar list.
+     */
+    getArchivedProjectPaths(): ProjectRepositoryRow[] {
+        const db = getConnection();
+        return db.prepare(`
+            SELECT project_id, project_path, custom_project_name, isStarred, isArchived
+            FROM projects
+            WHERE isArchived = 1
+        `).all() as ProjectRepositoryRow[];
+    },
+
     getCustomProjectName(projectPath: string): string | null {
         const db = getConnection();
         const normalizedProjectPath = normalizeProjectPath(projectPath);

server/modules/database/repositories/sessions.db.integration.test.ts

@@ -0,0 +1,72 @@
+import assert from 'node:assert/strict';
+import { mkdtemp, rm } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+import test from 'node:test';
+
+import { closeConnection } from '@/modules/database/connection.js';
+import { initializeDatabase } from '@/modules/database/init-db.js';
+import { sessionsDb } from '@/modules/database/repositories/sessions.db.js';
+
+async function withIsolatedDatabase(runTest: () => void | Promise<void>): Promise<void> {
+  const previousDatabasePath = process.env.DATABASE_PATH;
+  const tempDirectory = await mkdtemp(path.join(tmpdir(), 'sessions-db-'));
+  const databasePath = path.join(tempDirectory, 'auth.db');
+
+  closeConnection();
+  process.env.DATABASE_PATH = databasePath;
+  await initializeDatabase();
+
+  try {
+    await runTest();
+  } finally {
+    closeConnection();
+    if (previousDatabasePath === undefined) {
+      delete process.env.DATABASE_PATH;
+    } else {
+      process.env.DATABASE_PATH = previousDatabasePath;
+    }
+    await rm(tempDirectory, { recursive: true, force: true });
+  }
+}
+
+test('session archive queries hide archived rows from active project views', async () => {
+  await withIsolatedDatabase(() => {
+    sessionsDb.createSession('session-active', 'claude', '/workspace/demo-project', 'Active Session');
+    sessionsDb.createSession('session-archived', 'claude', '/workspace/demo-project', 'Archived Session');
+    sessionsDb.updateSessionIsArchived('session-archived', true);
+
+    const activeSessions = sessionsDb.getAllSessions();
+    const archivedSessions = sessionsDb.getArchivedSessions();
+    const activeProjectSessions = sessionsDb.getSessionsByProjectPath('/workspace/demo-project');
+    const allProjectSessions = sessionsDb.getSessionsByProjectPathIncludingArchived('/workspace/demo-project');
+
+    assert.deepEqual(activeSessions.map((session) => session.session_id), ['session-active']);
+    assert.deepEqual(archivedSessions.map((session) => session.session_id), ['session-archived']);
+    assert.deepEqual(activeProjectSessions.map((session) => session.session_id), ['session-active']);
+    assert.deepEqual(
+      allProjectSessions.map((session) => session.session_id).sort(),
+      ['session-active', 'session-archived'],
+    );
+    assert.equal(sessionsDb.countSessionsByProjectPath('/workspace/demo-project'), 1);
+  });
+});
+
+test('createSession reactivates archived rows when the session becomes active again', async () => {
+  await withIsolatedDatabase(() => {
+    sessionsDb.createSession('session-reused', 'claude', '/workspace/demo-project', 'First Name');
+    sessionsDb.updateSessionIsArchived('session-reused', true);
+
+    sessionsDb.createSession('session-reused', 'claude', '/workspace/demo-project', 'Updated Name');
+
+    const activeSessions = sessionsDb.getAllSessions();
+    const archivedSessions = sessionsDb.getArchivedSessions();
+    const restoredSession = sessionsDb.getSessionById('session-reused');
+
+    assert.equal(activeSessions.length, 1);
+    assert.equal(activeSessions[0]?.session_id, 'session-reused');
+    assert.equal(activeSessions[0]?.custom_name, 'Updated Name');
+    assert.equal(archivedSessions.length, 0);
+    assert.equal(restoredSession?.isArchived, 0);
+  });
+});

server/modules/database/repositories/sessions.db.ts

@@ -8,13 +8,14 @@ type SessionRow = {
   project_path: string | null;
   jsonl_path: string | null;
   custom_name: string | null;
+  isArchived: number;
   created_at: string;
   updated_at: string;
 };
 
 type SessionMetadataLookupRow = Pick<
   SessionRow,
-  'session_id' | 'provider' | 'project_path' | 'jsonl_path' | 'custom_name' | 'created_at' | 'updated_at'
+  'session_id' | 'provider' | 'project_path' | 'jsonl_path' | 'custom_name' | 'isArchived' | 'created_at' | 'updated_at'
 >;
 
 function normalizeTimestamp(value?: string): string | null {
@@ -53,13 +54,14 @@ export const sessionsDb = {
     projectsDb.createProjectPath(normalizedProjectPath);
 
     db.prepare(
-      `INSERT INTO sessions (session_id, provider, custom_name, project_path, jsonl_path, created_at, updated_at)
-       VALUES (?, ?, ?, ?, ?, COALESCE(?, CURRENT_TIMESTAMP), COALESCE(?, CURRENT_TIMESTAMP))
+      `INSERT INTO sessions (session_id, provider, custom_name, project_path, jsonl_path, isArchived, created_at, updated_at)
+       VALUES (?, ?, ?, ?, ?, 0, COALESCE(?, CURRENT_TIMESTAMP), COALESCE(?, CURRENT_TIMESTAMP))
        ON CONFLICT(session_id) DO UPDATE SET
          provider = excluded.provider,
          updated_at = excluded.updated_at,
          project_path = excluded.project_path,
          jsonl_path = excluded.jsonl_path,
+         isArchived = 0,
          custom_name = COALESCE(excluded.custom_name, sessions.custom_name)`
     ).run(
       sessionId,
@@ -87,7 +89,7 @@ export const sessionsDb = {
     const db = getConnection();
     const row = db
       .prepare(
-        `SELECT session_id, provider, project_path, jsonl_path, custom_name, created_at, updated_at
+        `SELECT session_id, provider, project_path, jsonl_path, custom_name, isArchived, created_at, updated_at
          FROM sessions
          WHERE session_id = ?
          ORDER BY updated_at DESC
@@ -102,8 +104,25 @@ export const sessionsDb = {
     const db = getConnection();
     return db
       .prepare(
-        `SELECT session_id, provider, project_path, jsonl_path, custom_name, created_at, updated_at
-         FROM sessions`
+        `SELECT session_id, provider, project_path, jsonl_path, custom_name, isArchived, created_at, updated_at
+         FROM sessions
+         WHERE isArchived = 0`
+      )
+      .all() as SessionRow[];
+  },
+
+  /**
+   * Archived rows are intentionally queried separately so the caller can render
+   * them in a dedicated view without reintroducing them into active session lists.
+   */
+  getArchivedSessions(): SessionRow[] {
+    const db = getConnection();
+    return db
+      .prepare(
+        `SELECT session_id, provider, project_path, jsonl_path, custom_name, isArchived, created_at, updated_at
+         FROM sessions
+         WHERE isArchived = 1
+         ORDER BY datetime(COALESCE(updated_at, created_at)) DESC, session_id DESC`
       )
       .all() as SessionRow[];
   },
@@ -113,7 +132,24 @@ export const sessionsDb = {
     const normalizedProjectPath = normalizeProjectPath(projectPath);
     return db
       .prepare(
-        `SELECT session_id, provider, project_path, jsonl_path, custom_name, created_at, updated_at
+        `SELECT session_id, provider, project_path, jsonl_path, custom_name, isArchived, created_at, updated_at
+         FROM sessions
+         WHERE project_path = ?
+           AND isArchived = 0`
+      )
+      .all(normalizedProjectPath) as SessionRow[];
+  },
+
+  /**
+   * Permanent project deletion must see every session row for the path,
+   * including archived ones, so their transcript files can be cleaned up.
+   */
+  getSessionsByProjectPathIncludingArchived(projectPath: string): SessionRow[] {
+    const db = getConnection();
+    const normalizedProjectPath = normalizeProjectPath(projectPath);
+    return db
+      .prepare(
+        `SELECT session_id, provider, project_path, jsonl_path, custom_name, isArchived, created_at, updated_at
          FROM sessions
          WHERE project_path = ?`
       )
@@ -125,9 +161,10 @@ export const sessionsDb = {
     const normalizedProjectPath = normalizeProjectPath(projectPath);
     return db
       .prepare(
-        `SELECT session_id, provider, project_path, jsonl_path, custom_name, created_at, updated_at
+        `SELECT session_id, provider, project_path, jsonl_path, custom_name, isArchived, created_at, updated_at
          FROM sessions
          WHERE project_path = ?
+           AND isArchived = 0
          ORDER BY datetime(COALESCE(updated_at, created_at)) DESC, session_id DESC
          LIMIT ? OFFSET ?`
       )
@@ -141,7 +178,8 @@ export const sessionsDb = {
       .prepare(
         `SELECT COUNT(*) AS count
          FROM sessions
-         WHERE project_path = ?`
+         WHERE project_path = ?
+           AND isArchived = 0`
       )
       .get(normalizedProjectPath) as { count: number } | undefined;
 
@@ -167,6 +205,19 @@ export const sessionsDb = {
     return row?.custom_name ?? null;
   },
 
+  /**
+   * Soft-delete and restore both use the same flag update so callers keep the
+   * row, metadata, and file path intact while toggling visibility.
+   */
+  updateSessionIsArchived(sessionId: string, isArchived: boolean): void {
+    const db = getConnection();
+    db.prepare(
+      `UPDATE sessions
+       SET isArchived = ?
+       WHERE session_id = ?`
+    ).run(isArchived ? 1 : 0, sessionId);
+  },
+
   deleteSessionById(sessionId: string): boolean {
     const db = getConnection();
     return db.prepare('DELETE FROM sessions WHERE session_id = ?').run(sessionId).changes > 0;

server/modules/database/schema.ts

@@ -86,6 +86,7 @@ CREATE TABLE IF NOT EXISTS sessions (
     custom_name TEXT,
     project_path TEXT,
     jsonl_path TEXT,
+    isArchived BOOLEAN DEFAULT 0,
     created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     updated_at DATETIME DEFAULT CURRENT_TIMESTAMP,
     PRIMARY KEY (session_id),

server/modules/projects/projects.routes.ts

@@ -3,9 +3,9 @@ import express from 'express';
 import { createProject, updateProjectDisplayName } from '@/modules/projects/services/project-management.service.js';
 import { startCloneProject } from '@/modules/projects/services/project-clone.service.js';
 import { getProjectTaskMaster } from '@/modules/projects/services/projects-has-taskmaster.service.js';
-import { AppError, asyncHandler } from '@/shared/utils.js';
-import { getProjectSessionsPage, getProjectsWithSessions } from '@/modules/projects/services/projects-with-sessions-fetch.service.js';
-import { deleteOrArchiveProject } from '@/modules/projects/services/project-delete.service.js';
+import { AppError, asyncHandler, createApiSuccessResponse } from '@/shared/utils.js';
+import { getArchivedProjectsWithSessions, getProjectSessionsPage, getProjectsWithSessions } from '@/modules/projects/services/projects-with-sessions-fetch.service.js';
+import { deleteOrArchiveProject, restoreArchivedProject } from '@/modules/projects/services/project-delete.service.js';
 import { applyLegacyStarredProjectIds, toggleProjectStar } from '@/modules/projects/services/project-star.service.js';
 
 const router = express.Router();
@@ -73,6 +73,14 @@ router.get(
   }),
 );
 
+router.get(
+  '/archived',
+  asyncHandler(async (_req, res) => {
+    const projects = await getArchivedProjectsWithSessions();
+    res.json(createApiSuccessResponse({ projects }));
+  }),
+);
+
 router.get(
   '/:projectId/sessions',
   asyncHandler(async (req, res) => {
@@ -230,6 +238,15 @@ router.post(
   }),
 );
 
+router.post(
+  '/:projectId/restore',
+  asyncHandler(async (req, res) => {
+    const projectId = typeof req.params.projectId === 'string' ? req.params.projectId : '';
+    restoreArchivedProject(projectId);
+    res.json(createApiSuccessResponse({ projectId, isArchived: false }));
+  }),
+);
+
 /**
  * - `force` not set / false: archive project in DB only (`isArchived` = 1; hidden from active list).
  * - `force=true`: remove DB row, delete session rows for that path, remove all `*.jsonl` under the Claude project dir.

server/modules/projects/services/project-delete.service.ts

@@ -42,7 +42,7 @@ async function unlinkJsonlIfExists(filePath: string): Promise<void> {
  * Loads all session rows for the project path and removes each distinct `jsonl_path` file on disk.
  */
 export async function deleteSessionJsonlFilesForProjectPath(projectPath: string): Promise<void> {
-  const sessions = sessionsDb.getSessionsByProjectPath(projectPath);
+  const sessions = sessionsDb.getSessionsByProjectPathIncludingArchived(projectPath);
   const paths = uniqueJsonlPathsFromSessions(sessions);
 
   for (const filePath of paths) {
@@ -73,3 +73,18 @@ export async function deleteOrArchiveProject(projectId: string, force: boolean):
   sessionsDb.deleteSessionsByProjectPath(row.project_path);
   projectsDb.deleteProjectById(projectId);
 }
+
+/**
+ * Restores one archived project row back into the active project list.
+ */
+export function restoreArchivedProject(projectId: string): void {
+  const row = projectsDb.getProjectById(projectId);
+  if (!row) {
+    throw new AppError(`Unknown projectId: ${projectId}`, {
+      code: 'PROJECT_NOT_FOUND',
+      statusCode: 404,
+    });
+  }
+
+  projectsDb.updateProjectIsArchivedById(projectId, false);
+}

server/modules/projects/services/projects-with-sessions-fetch.service.ts

@@ -40,6 +40,10 @@ export type ProjectListItem = {
   };
 };
 
+export type ArchivedProjectListItem = ProjectListItem & {
+  isArchived: true;
+};
+
 type ProgressUpdate = {
   phase: 'loading' | 'complete';
   current: number;
@@ -150,6 +154,16 @@ function bucketSessionRowsByProvider(rows: SessionRepositoryRow[]): SessionsByPr
   return byProvider;
 }
 
+function readProjectSessionsIncludingArchived(projectPath: string): ProjectSessionsPageResult {
+  const rows = sessionsDb.getSessionsByProjectPathIncludingArchived(projectPath) as SessionRepositoryRow[];
+
+  return {
+    sessionsByProvider: bucketSessionRowsByProvider(rows),
+    total: rows.length,
+    hasMore: false,
+  };
+}
+
 /**
  * Reads one paginated project session slice from the DB and groups rows by provider.
  */
@@ -255,6 +269,56 @@ export async function getProjectsWithSessions(
   return projects;
 }
 
+/**
+ * Reads archived projects from DB and includes every session row for each
+ * project path, because an archived workspace should surface all preserved
+ * conversation history in the archive view regardless of each session's flag.
+ */
+export async function getArchivedProjectsWithSessions(
+  options: Pick<GetProjectsWithSessionsOptions, 'skipSynchronization'> = {},
+): Promise<ArchivedProjectListItem[]> {
+  if (!options.skipSynchronization) {
+    await sessionSynchronizerService.synchronizeSessions();
+  }
+
+  const projectRows = projectsDb.getArchivedProjectPaths() as Array<{
+    project_id: string;
+    project_path: string;
+    custom_project_name?: string | null;
+    isStarred?: number;
+  }>;
+
+  const archivedProjects: ArchivedProjectListItem[] = [];
+
+  for (const row of projectRows) {
+    const displayName =
+      row.custom_project_name && row.custom_project_name.trim().length > 0
+        ? row.custom_project_name
+        : await generateDisplayName(path.basename(row.project_path) || row.project_path, row.project_path);
+
+    const sessionsPage = readProjectSessionsIncludingArchived(row.project_path);
+
+    archivedProjects.push({
+      projectId: row.project_id,
+      path: row.project_path,
+      displayName,
+      fullPath: row.project_path,
+      isStarred: Boolean(row.isStarred),
+      isArchived: true,
+      sessions: sessionsPage.sessionsByProvider.claude,
+      cursorSessions: sessionsPage.sessionsByProvider.cursor,
+      codexSessions: sessionsPage.sessionsByProvider.codex,
+      geminiSessions: sessionsPage.sessionsByProvider.gemini,
+      sessionMeta: {
+        hasMore: sessionsPage.hasMore,
+        total: sessionsPage.total,
+      },
+    });
+  }
+
+  return archivedProjects;
+}
+
 /**
  * Loads one paginated session slice for a specific project id.
  */

server/modules/providers/provider.routes.ts

@@ -311,12 +311,33 @@ router.post(
 );
 
 // ----------------- Session routes -----------------
+router.get(
+  '/sessions/archived',
+  asyncHandler(async (_req: Request, res: Response) => {
+    const sessions = sessionsService.listArchivedSessions();
+    res.json(createApiSuccessResponse({ sessions }));
+  }),
+);
+
 router.delete(
   '/sessions/:sessionId',
   asyncHandler(async (req: Request, res: Response) => {
     const sessionId = parseSessionId(req.params.sessionId);
-    const deletedFromDisk = parseOptionalBooleanQuery(req.query.deletedFromDisk, 'deletedFromDisk') ?? false;
-    const result = await sessionsService.deleteSessionById(sessionId, deletedFromDisk);
+    const force = parseOptionalBooleanQuery(req.query.force, 'force') ?? false;
+    const deletedFromDisk = parseOptionalBooleanQuery(req.query.deletedFromDisk, 'deletedFromDisk') ?? force;
+    const result = await sessionsService.deleteOrArchiveSessionById(sessionId, {
+      force,
+      deletedFromDisk,
+    });
+    res.json(createApiSuccessResponse(result));
+  }),
+);
+
+router.post(
+  '/sessions/:sessionId/restore',
+  asyncHandler(async (req: Request, res: Response) => {
+    const sessionId = parseSessionId(req.params.sessionId);
+    const result = sessionsService.restoreSessionById(sessionId);
     res.json(createApiSuccessResponse(result));
   }),
 );

server/modules/providers/services/sessions.service.ts

@@ -1,6 +1,7 @@
 import fsp from 'node:fs/promises';
+import path from 'node:path';
 
-import { sessionsDb } from '@/modules/database/index.js';
+import { projectsDb, sessionsDb } from '@/modules/database/index.js';
 import { providerRegistry } from '@/modules/providers/provider.registry.js';
 import type {
   FetchHistoryOptions,
@@ -10,6 +11,19 @@ import type {
 } from '@/shared/types.js';
 import { AppError } from '@/shared/utils.js';
 
+type ArchivedSessionListItem = {
+  sessionId: string;
+  provider: LLMProvider;
+  projectId: string | null;
+  projectPath: string | null;
+  projectDisplayName: string;
+  sessionTitle: string;
+  createdAt: string | null;
+  updatedAt: string | null;
+  lastActivity: string | null;
+  isProjectArchived: boolean;
+};
+
 /**
  * Removes one file if it exists.
  */
@@ -26,6 +40,28 @@ async function removeFileIfExists(filePath: string): Promise<boolean> {
   }
 }
 
+/**
+ * Archive rows need a stable project label even when the owning project is not
+ * part of the active sidebar payload. This lightweight resolver keeps the
+ * archive API self-contained while still matching the project's stored display
+ * name when one exists.
+ */
+function resolveProjectDisplayName(
+  projectPath: string | null,
+  customProjectName: string | null | undefined,
+): string {
+  const trimmedCustomName = typeof customProjectName === 'string' ? customProjectName.trim() : '';
+  if (trimmedCustomName.length > 0) {
+    return trimmedCustomName;
+  }
+
+  if (!projectPath) {
+    return 'Unknown Project';
+  }
+
+  return path.basename(projectPath) || projectPath;
+}
+
 /**
  * Application service for provider-backed session message operations.
  *
@@ -79,15 +115,53 @@ export const sessionsService = {
   },
 
   /**
-   * Deletes one persisted session row by id.
-   *
-   * When `deletedFromDisk` is true and a session `jsonl_path` exists, the path
-   * is deleted from disk before the DB row is removed.
+   * Returns archived sessions with enough project metadata for the sidebar to
+   * group, filter, open, and restore them without a per-row follow-up query.
    */
-  async deleteSessionById(
+  listArchivedSessions(): ArchivedSessionListItem[] {
+    const archivedSessions = sessionsDb.getArchivedSessions();
+    const projectCache = new Map<string, ReturnType<typeof projectsDb.getProjectPath>>();
+
+    return archivedSessions.map((session) => {
+      const projectPath = session.project_path?.trim() ? session.project_path : null;
+      let project = null;
+
+      if (projectPath) {
+        if (!projectCache.has(projectPath)) {
+          projectCache.set(projectPath, projectsDb.getProjectPath(projectPath));
+        }
+        project = projectCache.get(projectPath) ?? null;
+      }
+
+      return {
+        sessionId: session.session_id,
+        provider: session.provider as LLMProvider,
+        projectId: project?.project_id ?? null,
+        projectPath,
+        projectDisplayName: resolveProjectDisplayName(projectPath, project?.custom_project_name),
+        sessionTitle: session.custom_name?.trim() || session.session_id,
+        createdAt: session.created_at ?? null,
+        updatedAt: session.updated_at ?? null,
+        lastActivity: session.updated_at ?? session.created_at ?? null,
+        isProjectArchived: Boolean(project?.isArchived),
+      };
+    });
+  },
+
+  /**
+   * Archives or permanently deletes one persisted session row by id.
+   *
+   * Soft-delete mirrors the project behavior by toggling `isArchived` so the
+   * row disappears from active lists but remains restorable. Force-delete
+   * optionally removes the transcript file before deleting the database row.
+   */
+  async deleteOrArchiveSessionById(
     sessionId: string,
-    deletedFromDisk = false,
-  ): Promise<{ sessionId: string; deletedFromDisk: boolean }> {
+    options: {
+      force?: boolean;
+      deletedFromDisk?: boolean;
+    } = {},
+  ): Promise<{ sessionId: string; action: 'archived' | 'deleted'; deletedFromDisk: boolean }> {
     const session = sessionsDb.getSessionById(sessionId);
     if (!session) {
       throw new AppError(`Session "${sessionId}" was not found.`, {
@@ -96,8 +170,17 @@ export const sessionsService = {
       });
     }
 
+    if (!options.force) {
+      sessionsDb.updateSessionIsArchived(sessionId, true);
+      return {
+        sessionId,
+        action: 'archived',
+        deletedFromDisk: false,
+      };
+    }
+
     let removedFromDisk = false;
-    if (deletedFromDisk && session.jsonl_path) {
+    if (options.deletedFromDisk && session.jsonl_path) {
       removedFromDisk = await removeFileIfExists(session.jsonl_path);
     }
 
@@ -109,7 +192,27 @@ export const sessionsService = {
       });
     }
 
-    return { sessionId, deletedFromDisk: removedFromDisk };
+    return {
+      sessionId,
+      action: 'deleted',
+      deletedFromDisk: removedFromDisk,
+    };
+  },
+
+  /**
+   * Restores one archived session back into the active sidebar lists.
+   */
+  restoreSessionById(sessionId: string): { sessionId: string; isArchived: false } {
+    const session = sessionsDb.getSessionById(sessionId);
+    if (!session) {
+      throw new AppError(`Session "${sessionId}" was not found.`, {
+        code: 'SESSION_NOT_FOUND',
+        statusCode: 404,
+      });
+    }
+
+    sessionsDb.updateSessionIsArchived(sessionId, false);
+    return { sessionId, isArchived: false };
   },
 
   /**