diff --git a/packages/http-routes/src/routes/shared-routes.test.ts b/packages/http-routes/src/routes/shared-routes.test.ts
index 19e97d14..fe843727 100644
--- a/packages/http-routes/src/routes/shared-routes.test.ts
+++ b/packages/http-routes/src/routes/shared-routes.test.ts
@@ -7,10 +7,13 @@
 
 import { describe, it, before, after } from 'node:test'
 import assert from 'node:assert/strict'
+import fs from 'node:fs'
+import os from 'node:os'
+import path from 'node:path'
 import Database from 'better-sqlite3'
 import Fastify, { type FastifyInstance } from 'fastify'
 import type { DatabaseAdapter, PathProvider, PreparedStatement, RunResult } from '@openchatlab/core'
-import type { DatabaseManager, SessionRuntimeAdapter } from '@openchatlab/node-runtime'
+import { PreferencesManager, type DatabaseManager, type SessionRuntimeAdapter } from '@openchatlab/node-runtime'
 import type { HttpRouteContext } from '../context'
 import { registerSharedRoutes } from '../register'
 import { registerRestSessionRoutes } from './sessions'
@@ -293,4 +296,64 @@ describe('registerSharedRoutes smoke tests', () => {
     assert.deepEqual(resp.json(), { success: true })
     assert.equal(dbs.has('chat-1'), false)
   })
+
+  it('owner profile routes select, apply and dismiss across sessions', async () => {
+    const prefDir = fs.mkdtempSync(path.join(os.tmpdir(), 'chatlab-owner-routes-'))
+    const current = createSessionDb()
+    current.exec(`UPDATE meta SET owner_id = NULL, platform = 'whatsapp'`)
+    const other = createSessionDb()
+    other.exec(`UPDATE meta SET owner_id = NULL, platform = 'whatsapp'`)
+    const dismissedOnly = createSessionDb()
+    dismissedOnly.exec(`UPDATE meta SET owner_id = NULL, platform = 'whatsapp'; DELETE FROM member`)
+
+    const dbs = new Map<string, DatabaseAdapter>([
+      ['chat-1', current],
+      ['chat-2', other],
+      ['chat-3', dismissedOnly],
+    ])
+    const ctx = createTestContext(dbs)
+    ctx.preferencesManager = new PreferencesManager(prefDir)
+    const routeApp = Fastify()
+    registerSessionRoutes(routeApp, ctx)
+    await routeApp.ready()
+
+    try {
+      // Dismiss the prompt for chat-3 (no matching member there)
+      const dismissResp = await routeApp.inject({ method: 'POST', url: '/_web/sessions/chat-3/owner/dismiss-prompt' })
+      assert.equal(dismissResp.statusCode, 200)
+      assert.deepEqual(dismissResp.json(), { success: true })
+
+      // apply-profile before any profile exists reports no_profile and the dismissed flag
+      const earlyApply = await routeApp.inject({ method: 'POST', url: '/_web/sessions/chat-3/owner/apply-profile' })
+      assert.equal(earlyApply.statusCode, 200)
+      assert.deepEqual(earlyApply.json(), { applied: false, reason: 'no_profile', dismissed: true })
+
+      // Manual selection writes owner, saves profile and batch-applies to chat-2
+      const selectResp = await routeApp.inject({
+        method: 'POST',
+        url: '/_web/sessions/chat-1/owner/select',
+        payload: { ownerPlatformId: 'alice' },
+      })
+      assert.equal(selectResp.statusCode, 200)
+      const selectBody = selectResp.json()
+      assert.equal(selectBody.ownerId, 'alice')
+      assert.equal(selectBody.platform, 'whatsapp')
+      assert.deepEqual(selectBody.updatedSessionIds, ['chat-2'])
+      const currentMeta = current.prepare('SELECT owner_id FROM meta LIMIT 1').get() as { owner_id: string }
+      const otherMeta = other.prepare('SELECT owner_id FROM meta LIMIT 1').get() as { owner_id: string }
+      assert.equal(currentMeta.owner_id, 'alice')
+      assert.equal(otherMeta.owner_id, 'alice')
+
+      // apply-profile on an already-owned session reports already_set
+      const applyResp = await routeApp.inject({ method: 'POST', url: '/_web/sessions/chat-2/owner/apply-profile' })
+      assert.equal(applyResp.statusCode, 200)
+      assert.deepEqual(applyResp.json(), { applied: false, ownerId: 'alice', reason: 'already_set', dismissed: false })
+    } finally {
+      await routeApp.close()
+      current.close()
+      other.close()
+      dismissedOnly.close()
+      fs.rmSync(prefDir, { recursive: true, force: true })
+    }
+  })
 })
diff --git a/packages/http-routes/src/routes/web/sessions.ts b/packages/http-routes/src/routes/web/sessions.ts
index 2ddc7e81..0555514a 100644
--- a/packages/http-routes/src/routes/web/sessions.ts
+++ b/packages/http-routes/src/routes/web/sessions.ts
@@ -1,10 +1,17 @@
 import type { FastifyInstance } from 'fastify'
 import type { HttpRouteContext } from '../../context'
-import { sessionService } from '@openchatlab/node-runtime'
+import { sessionService, ownerProfileService, PreferencesManager } from '@openchatlab/node-runtime'
 
 export function registerSessionRoutes(server: FastifyInstance, ctx: HttpRouteContext): void {
   const { sessionAdapter: adapter } = ctx
 
+  // Lazy: only owner-profile routes need preferences.json access
+  let preferencesInstance: PreferencesManager | null = null
+  const preferences = () => {
+    preferencesInstance ??= ctx.preferencesManager ?? new PreferencesManager(ctx.pathProvider.getSystemDir())
+    return preferencesInstance
+  }
+
   server.get('/_web/sessions', async () => {
     return sessionService.listAnalysisSessions(adapter)
   })
@@ -42,4 +49,29 @@ export function registerSessionRoutes(server: FastifyInstance, ctx: HttpRouteCon
       return { success: true }
     }
   )
+
+  // Try to auto-apply the stored platform owner profile to this session.
+  server.post<{ Params: { id: string } }>('/_web/sessions/:id/owner/apply-profile', async (request) => {
+    return ownerProfileService.tryApplyOwnerProfile(adapter, preferences(), request.params.id)
+  })
+
+  // Manually select owner: writes meta.owner_id, updates the platform profile,
+  // and batch-applies it to other unowned same-platform sessions.
+  server.post<{ Params: { id: string }; Body: { ownerPlatformId: string } }>(
+    '/_web/sessions/:id/owner/select',
+    async (request) => {
+      return ownerProfileService.setOwnerAndApplyProfile(
+        adapter,
+        preferences(),
+        request.params.id,
+        request.body.ownerPlatformId
+      )
+    }
+  )
+
+  // Suppress the owner prompt for this session (UI-only).
+  server.post<{ Params: { id: string } }>('/_web/sessions/:id/owner/dismiss-prompt', async (request) => {
+    ownerProfileService.dismissOwnerPrompt(preferences(), request.params.id)
+    return { success: true }
+  })
 }
diff --git a/packages/node-runtime/src/index.ts b/packages/node-runtime/src/index.ts
index fbd34fe5..876a090f 100644
--- a/packages/node-runtime/src/index.ts
+++ b/packages/node-runtime/src/index.ts
@@ -404,6 +404,7 @@ export * as memberService from './services/member-service'
 export * as sessionIndexService from './services/session-index-service'
 export * as summaryService from './services/summary-service'
 export * as exportService from './services/export-service'
+export * as ownerProfileService from './services/owner-profile-service'
 export { createDatabaseManagerAdapter, MergeSessionCache } from './services'
 export type {
   SessionRuntimeAdapter,
@@ -412,4 +413,7 @@ export type {
   MembersPaginatedDTO,
   LlmConfig,
   SummaryServiceDeps,
+  ApplyOwnerProfileReason,
+  ApplyOwnerProfileResult,
+  SetOwnerAndApplyProfileResult,
 } from './services'
diff --git a/packages/node-runtime/src/services/index.ts b/packages/node-runtime/src/services/index.ts
index 30cb6365..c7804f7d 100644
--- a/packages/node-runtime/src/services/index.ts
+++ b/packages/node-runtime/src/services/index.ts
@@ -23,6 +23,19 @@ export {
 } from './member-service'
 export type { MembersPaginatedDTO } from './member-service'
 
+// Owner profile service
+export {
+  tryApplyOwnerProfile,
+  setOwnerAndApplyProfile,
+  dismissOwnerPrompt,
+  clearSessionOwner,
+} from './owner-profile-service'
+export type {
+  ApplyOwnerProfileReason,
+  ApplyOwnerProfileResult,
+  SetOwnerAndApplyProfileResult,
+} from './owner-profile-service'
+
 // Session index service
 export {
   generateIndex,
diff --git a/packages/node-runtime/src/services/owner-profile-service.test.ts b/packages/node-runtime/src/services/owner-profile-service.test.ts
new file mode 100644
index 00000000..a75b4cd0
--- /dev/null
+++ b/packages/node-runtime/src/services/owner-profile-service.test.ts
@@ -0,0 +1,314 @@
+/**
+ * Integration tests for the owner profile service, against real SQLite
+ * session databases and a real preferences.json file.
+ *
+ * Run: pnpm test -- packages/node-runtime/src/services/owner-profile-service.test.ts
+ */
+
+import assert from 'node:assert/strict'
+import fs from 'node:fs'
+import os from 'node:os'
+import path from 'node:path'
+import test from 'node:test'
+import { CHAT_DB_SCHEMA, getSessionMeta } from '@openchatlab/core'
+import type { DatabaseAdapter } from '@openchatlab/core'
+import { openBetterSqliteDatabase } from '../better-sqlite3-adapter'
+import { PreferencesManager } from '../preferences'
+import type { SessionRuntimeAdapter } from './adapters'
+import {
+  tryApplyOwnerProfile,
+  setOwnerAndApplyProfile,
+  dismissOwnerPrompt,
+  clearSessionOwner,
+} from './owner-profile-service'
+
+const nativeBinding = path.resolve('apps/cli/native/better_sqlite3.node')
+
+function makeTempDir(): string {
+  const baseDir = fs.existsSync('/private/tmp') ? '/private/tmp' : os.tmpdir()
+  return fs.mkdtempSync(path.join(baseDir, 'chatlab-owner-profile-'))
+}
+
+interface SeedMember {
+  platformId: string
+  accountName?: string
+  groupNickname?: string
+  aliases?: string[]
+}
+
+interface SeedSession {
+  id: string
+  platform: string
+  type?: 'group' | 'private'
+  ownerId?: string | null
+  members: SeedMember[]
+}
+
+class TestEnv {
+  readonly dir: string
+  readonly preferences: PreferencesManager
+  readonly adapter: SessionRuntimeAdapter
+  private dbPaths = new Map<string, string>()
+  private openDbs: DatabaseAdapter[] = []
+
+  constructor() {
+    this.dir = makeTempDir()
+    this.preferences = new PreferencesManager(this.dir)
+    const open = (sessionId: string, readonly: boolean): DatabaseAdapter | null => {
+      const dbPath = this.dbPaths.get(sessionId)
+      if (!dbPath) return null
+      const db = openBetterSqliteDatabase(dbPath, { readonly, nativeBinding })
+      this.openDbs.push(db)
+      return db
+    }
+    this.adapter = {
+      listSessionIds: () => [...this.dbPaths.keys()],
+      openReadonly: (id) => open(id, true),
+      openWritable: (id) => open(id, false),
+      closeSession: () => {},
+      getDbPath: (id) => this.dbPaths.get(id) ?? '',
+      deleteSessionFile: () => false,
+      ensureReadonly: (id) => {
+        const db = open(id, true)
+        if (!db) throw Object.assign(new Error(`Session not found: ${id}`), { statusCode: 404 })
+        return db
+      },
+      ensureWritable: (id) => {
+        const db = open(id, false)
+        if (!db) throw Object.assign(new Error(`Session not found: ${id}`), { statusCode: 404 })
+        return db
+      },
+    }
+  }
+
+  seed(session: SeedSession): void {
+    const dbPath = path.join(this.dir, `${session.id}.db`)
+    const db = openBetterSqliteDatabase(dbPath, { nativeBinding })
+    db.exec(CHAT_DB_SCHEMA)
+    db.prepare(`INSERT INTO meta (name, platform, type, imported_at, owner_id) VALUES (?, ?, ?, ?, ?)`).run(
+      session.id,
+      session.platform,
+      session.type ?? 'group',
+      1780000000,
+      session.ownerId ?? null
+    )
+    for (const member of session.members) {
+      db.prepare(`INSERT INTO member (platform_id, account_name, group_nickname, aliases) VALUES (?, ?, ?, ?)`).run(
+        member.platformId,
+        member.accountName ?? null,
+        member.groupNickname ?? null,
+        JSON.stringify(member.aliases ?? [])
+      )
+    }
+    db.close()
+    this.dbPaths.set(session.id, dbPath)
+  }
+
+  ownerOf(sessionId: string): string | null {
+    const db = this.adapter.ensureReadonly(sessionId)
+    return getSessionMeta(db)?.ownerId ?? null
+  }
+
+  cleanup(): void {
+    for (const db of this.openDbs) {
+      try {
+        db.close()
+      } catch {
+        // already closed
+      }
+    }
+    fs.rmSync(this.dir, { recursive: true, force: true })
+  }
+}
+
+test('setOwnerAndApplyProfile writes owner, saves platform profile and merges names', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({
+    id: 's1',
+    platform: 'whatsapp',
+    members: [
+      { platformId: 'Alice', accountName: 'Alice', groupNickname: 'Ali', aliases: ['Allie'] },
+      { platformId: 'Bob' },
+    ],
+  })
+
+  const result = setOwnerAndApplyProfile(env.adapter, env.preferences, 's1', 'Alice')
+  assert.equal(result.ownerId, 'Alice')
+  assert.equal(result.platform, 'whatsapp')
+  assert.deepEqual(result.updatedSessionIds, [])
+  assert.equal(env.ownerOf('s1'), 'Alice')
+
+  env.preferences.invalidateCache()
+  const profile = env.preferences.load().ownerProfilesByPlatform['whatsapp']
+  assert.ok(profile)
+  assert.equal(profile.platformId, 'Alice')
+  assert.equal(profile.matchMode, 'name')
+  assert.deepEqual(profile.confirmedNames, ['Alice', 'Ali', 'Allie'])
+})
+
+test('setOwnerAndApplyProfile batch-applies to unowned same-platform sessions only', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({ id: 'current', platform: 'whatsapp', members: [{ platformId: 'Alice' }, { platformId: 'Bob' }] })
+  // Name fallback match (different platformId, same normalized name)
+  env.seed({ id: 'name-match', platform: 'whatsapp', members: [{ platformId: 'alice' }, { platformId: 'Carol' }] })
+  // Already owned: never overridden
+  env.seed({ id: 'owned', platform: 'whatsapp', ownerId: 'Bob', members: [{ platformId: 'Alice' }] })
+  // Different platform: untouched
+  env.seed({ id: 'other-platform', platform: 'telegram', members: [{ platformId: 'Alice' }] })
+  // Ambiguous: two members normalize to the same confirmed name
+  env.seed({
+    id: 'ambiguous',
+    platform: 'whatsapp',
+    members: [{ platformId: 'alice' }, { platformId: 'u2', accountName: 'ALICE' }],
+  })
+  // No match
+  env.seed({ id: 'no-match', platform: 'whatsapp', members: [{ platformId: 'Dave' }] })
+
+  const result = setOwnerAndApplyProfile(env.adapter, env.preferences, 'current', 'Alice')
+  assert.deepEqual(result.updatedSessionIds, ['name-match'])
+  assert.equal(env.ownerOf('name-match'), 'alice')
+  assert.equal(env.ownerOf('owned'), 'Bob')
+  assert.equal(env.ownerOf('other-platform'), null)
+  assert.equal(env.ownerOf('ambiguous'), null)
+  assert.equal(env.ownerOf('no-match'), null)
+})
+
+test('re-selecting a different member replaces the profile instead of merging names', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({ id: 's1', platform: 'whatsapp', members: [{ platformId: 'Alice' }, { platformId: 'Bob' }] })
+
+  setOwnerAndApplyProfile(env.adapter, env.preferences, 's1', 'Alice')
+  setOwnerAndApplyProfile(env.adapter, env.preferences, 's1', 'Bob')
+
+  env.preferences.invalidateCache()
+  const profile = env.preferences.load().ownerProfilesByPlatform['whatsapp']
+  assert.equal(profile.platformId, 'Bob')
+  assert.deepEqual(profile.confirmedNames, ['Bob'])
+})
+
+test('setOwnerAndApplyProfile rejects a platformId that is not a session member', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({ id: 's1', platform: 'whatsapp', members: [{ platformId: 'Alice' }] })
+  assert.throws(() => setOwnerAndApplyProfile(env.adapter, env.preferences, 's1', 'Nobody'), /Member not found/)
+})
+
+test('tryApplyOwnerProfile applies stored profile and reports reasons', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({ id: 'source', platform: 'whatsapp', members: [{ platformId: 'Alice' }] })
+  env.seed({ id: 'unowned', platform: 'whatsapp', members: [{ platformId: 'Alice' }, { platformId: 'Bob' }] })
+  env.seed({ id: 'no-profile', platform: 'telegram', members: [{ platformId: 'Alice' }] })
+
+  // No profile saved yet
+  assert.deepEqual(tryApplyOwnerProfile(env.adapter, env.preferences, 'unowned'), {
+    applied: false,
+    reason: 'no_profile',
+    dismissed: false,
+  })
+
+  setOwnerAndApplyProfile(env.adapter, env.preferences, 'source', 'Alice')
+  // 'unowned' was already auto-filled by batch apply
+  assert.equal(env.ownerOf('unowned'), 'Alice')
+  assert.deepEqual(tryApplyOwnerProfile(env.adapter, env.preferences, 'unowned'), {
+    applied: false,
+    ownerId: 'Alice',
+    reason: 'already_set',
+    dismissed: false,
+  })
+
+  // New session imported later: profile applies on demand
+  env.seed({ id: 'later', platform: 'whatsapp', members: [{ platformId: 'Alice' }, { platformId: 'Carol' }] })
+  const applied = tryApplyOwnerProfile(env.adapter, env.preferences, 'later')
+  assert.deepEqual(applied, { applied: true, ownerId: 'Alice', dismissed: false })
+  assert.equal(env.ownerOf('later'), 'Alice')
+
+  assert.deepEqual(tryApplyOwnerProfile(env.adapter, env.preferences, 'no-profile'), {
+    applied: false,
+    reason: 'no_profile',
+    dismissed: false,
+  })
+  assert.equal(tryApplyOwnerProfile(env.adapter, env.preferences, 'missing').reason, 'missing_session')
+})
+
+test('dismissOwnerPrompt persists and is cleared by manual owner selection', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({ id: 's1', platform: 'whatsapp', members: [{ platformId: 'Alice' }] })
+
+  dismissOwnerPrompt(env.preferences, 's1')
+  dismissOwnerPrompt(env.preferences, 's1')
+  env.preferences.invalidateCache()
+  assert.deepEqual(env.preferences.load().ownerPromptDismissedSessionIds, ['s1'])
+  assert.equal(tryApplyOwnerProfile(env.adapter, env.preferences, 's1').dismissed, true)
+
+  setOwnerAndApplyProfile(env.adapter, env.preferences, 's1', 'Alice')
+  env.preferences.invalidateCache()
+  assert.deepEqual(env.preferences.load().ownerPromptDismissedSessionIds, [])
+})
+
+test('batch apply removes auto-filled sessions from the dismissed list', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({ id: 'current', platform: 'whatsapp', members: [{ platformId: 'Alice' }] })
+  env.seed({ id: 'other', platform: 'whatsapp', members: [{ platformId: 'Alice' }, { platformId: 'Bob' }] })
+
+  dismissOwnerPrompt(env.preferences, 'other')
+  const result = setOwnerAndApplyProfile(env.adapter, env.preferences, 'current', 'Alice')
+  assert.deepEqual(result.updatedSessionIds, ['other'])
+
+  env.preferences.invalidateCache()
+  assert.deepEqual(env.preferences.load().ownerPromptDismissedSessionIds, [])
+})
+
+test('clearSessionOwner clears the session owner but keeps the platform profile', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({ id: 's1', platform: 'whatsapp', members: [{ platformId: 'Alice' }] })
+  setOwnerAndApplyProfile(env.adapter, env.preferences, 's1', 'Alice')
+  assert.equal(env.ownerOf('s1'), 'Alice')
+
+  clearSessionOwner(env.adapter, 's1')
+  assert.equal(env.ownerOf('s1'), null)
+
+  env.preferences.invalidateCache()
+  assert.ok(env.preferences.load().ownerProfilesByPlatform['whatsapp'])
+})
+
+test('exact platformId match works on platforms without name fallback', (t) => {
+  const env = new TestEnv()
+  t.after(() => env.cleanup())
+
+  env.seed({ id: 'source', platform: 'weixin', members: [{ platformId: 'wx_me', accountName: 'Me' }] })
+  env.seed({
+    id: 'other',
+    platform: 'weixin',
+    members: [
+      { platformId: 'wx_me', accountName: 'Renamed' },
+      { platformId: 'wx_other', accountName: 'Me' },
+    ],
+  })
+
+  const result = setOwnerAndApplyProfile(env.adapter, env.preferences, 'source', 'wx_me')
+  assert.equal(result.platform, 'weixin')
+  assert.deepEqual(result.updatedSessionIds, ['other'])
+  assert.equal(env.ownerOf('other'), 'wx_me')
+
+  env.preferences.invalidateCache()
+  assert.equal(env.preferences.load().ownerProfilesByPlatform['weixin'].matchMode, 'platform_id')
+
+  // Name-only coincidence must NOT match on weixin
+  env.seed({ id: 'name-only', platform: 'weixin', members: [{ platformId: 'wx_x', accountName: 'Me' }] })
+  assert.equal(tryApplyOwnerProfile(env.adapter, env.preferences, 'name-only').reason, 'no_match')
+})
diff --git a/packages/node-runtime/src/services/owner-profile-service.ts b/packages/node-runtime/src/services/owner-profile-service.ts
new file mode 100644
index 00000000..96292fec
--- /dev/null
+++ b/packages/node-runtime/src/services/owner-profile-service.ts
@@ -0,0 +1,177 @@
+/**
+ * Shared owner profile service.
+ *
+ * Manages the platform-level "who am I" identity: writes per-session
+ * meta.owner_id, maintains ownerProfilesByPlatform in preferences.json, and
+ * applies a confirmed profile to other unowned sessions of the same platform.
+ * Used by both CLI Web routes and Electron IPC.
+ */
+
+import {
+  getSessionMeta,
+  getMembersWithAliases,
+  isChatSessionDb,
+  updateSessionOwnerId as coreUpdateSessionOwnerId,
+  matchOwnerProfile,
+  mergeConfirmedNames,
+  isNameMatchPlatform,
+} from '@openchatlab/core'
+import type { MemberWithAliases } from '@openchatlab/core'
+import type {
+  OwnerProfile,
+  ApplyOwnerProfileReason,
+  ApplyOwnerProfileResult,
+  SetOwnerAndApplyProfileResult,
+} from '@openchatlab/shared-types'
+import type { PreferencesManager } from '../preferences'
+import type { SessionRuntimeAdapter } from './adapters'
+
+export type { ApplyOwnerProfileReason, ApplyOwnerProfileResult, SetOwnerAndApplyProfileResult }
+
+function memberDisplayName(member: MemberWithAliases): string {
+  return member.groupNickname || member.accountName || member.platformId
+}
+
+function isDismissed(preferences: PreferencesManager, sessionId: string): boolean {
+  return preferences.load().ownerPromptDismissedSessionIds.includes(sessionId)
+}
+
+/**
+ * Try to apply the stored platform owner profile to one session.
+ * Writes meta.owner_id only on a unique (exact or name) match.
+ * Never overrides an existing owner.
+ */
+export function tryApplyOwnerProfile(
+  adapter: SessionRuntimeAdapter,
+  preferences: PreferencesManager,
+  sessionId: string
+): ApplyOwnerProfileResult {
+  const dismissed = isDismissed(preferences, sessionId)
+
+  const db = adapter.openReadonly(sessionId)
+  if (!db || !isChatSessionDb(db)) {
+    return { applied: false, reason: 'missing_session', dismissed }
+  }
+  const meta = getSessionMeta(db)
+  if (!meta) {
+    return { applied: false, reason: 'missing_session', dismissed }
+  }
+  if (meta.ownerId) {
+    return { applied: false, ownerId: meta.ownerId, reason: 'already_set', dismissed }
+  }
+
+  const profile = preferences.load().ownerProfilesByPlatform[meta.platform]
+  if (!profile) {
+    return { applied: false, reason: 'no_profile', dismissed }
+  }
+
+  const result = matchOwnerProfile(meta.platform, profile, getMembersWithAliases(db))
+  if (result.type === 'exact' || result.type === 'name') {
+    const writable = adapter.ensureWritable(sessionId)
+    coreUpdateSessionOwnerId(writable, result.platformId)
+    return { applied: true, ownerId: result.platformId, dismissed }
+  }
+  return { applied: false, reason: result.type === 'ambiguous' ? 'ambiguous' : 'no_match', dismissed }
+}
+
+/**
+ * Manually set the owner of one session, update the platform profile, and
+ * batch-apply the profile to other unowned sessions of the same platform.
+ *
+ * Re-selecting the same identity merges new names into confirmedNames;
+ * selecting a different member replaces the profile (names start fresh,
+ * so the previous person's names cannot cause wrong matches).
+ */
+export function setOwnerAndApplyProfile(
+  adapter: SessionRuntimeAdapter,
+  preferences: PreferencesManager,
+  sessionId: string,
+  ownerPlatformId: string
+): SetOwnerAndApplyProfileResult {
+  const db = adapter.ensureWritable(sessionId)
+  const meta = getSessionMeta(db)
+  if (!meta) {
+    throw Object.assign(new Error(`Session has no meta: ${sessionId}`), { statusCode: 404 })
+  }
+
+  const members = getMembersWithAliases(db)
+  const selected = members.find((m) => m.platformId === ownerPlatformId)
+  if (!selected) {
+    throw Object.assign(new Error(`Member not found in session: ${ownerPlatformId}`), { statusCode: 400 })
+  }
+
+  coreUpdateSessionOwnerId(db, ownerPlatformId)
+
+  const prefs = preferences.load()
+  const existing = prefs.ownerProfilesByPlatform[meta.platform]
+  const baseNames = existing && existing.platformId === ownerPlatformId ? existing.confirmedNames : []
+  const profile: OwnerProfile = {
+    platformId: ownerPlatformId,
+    displayName: memberDisplayName(selected),
+    confirmedNames: mergeConfirmedNames(baseNames, { ...selected, displayName: memberDisplayName(selected) }),
+    matchMode: isNameMatchPlatform(meta.platform) ? 'name' : 'platform_id',
+    updatedAt: Date.now(),
+  }
+
+  const updatedSessionIds = applyProfileToOtherSessions(adapter, meta.platform, profile, sessionId)
+
+  const noLongerDismissed = new Set([sessionId, ...updatedSessionIds])
+  preferences.save({
+    ownerProfilesByPlatform: { ...prefs.ownerProfilesByPlatform, [meta.platform]: profile },
+    ownerPromptDismissedSessionIds: prefs.ownerPromptDismissedSessionIds.filter((id) => !noLongerDismissed.has(id)),
+  })
+
+  return { sessionId, platform: meta.platform, ownerId: ownerPlatformId, updatedSessionIds }
+}
+
+/**
+ * Apply a profile to all other unowned sessions of the same platform.
+ * Unique match only; sessions with an existing owner are never touched.
+ */
+function applyProfileToOtherSessions(
+  adapter: SessionRuntimeAdapter,
+  platform: string,
+  profile: OwnerProfile,
+  excludeSessionId: string
+): string[] {
+  const updated: string[] = []
+  for (const id of adapter.listSessionIds()) {
+    if (id === excludeSessionId) continue
+    try {
+      const db = adapter.openReadonly(id)
+      if (!db || !isChatSessionDb(db)) continue
+      const meta = getSessionMeta(db)
+      if (!meta || meta.platform !== platform || meta.ownerId) continue
+
+      const result = matchOwnerProfile(platform, profile, getMembersWithAliases(db))
+      if (result.type === 'exact' || result.type === 'name') {
+        coreUpdateSessionOwnerId(adapter.ensureWritable(id), result.platformId)
+        updated.push(id)
+      }
+    } catch (err) {
+      console.warn(`[OwnerProfile] Failed to apply profile to session ${id}:`, err)
+    }
+  }
+  return updated
+}
+
+/**
+ * Suppress the owner prompt for one session. UI-only: does not imply owner
+ * knowledge and does not block later automatic profile application.
+ */
+export function dismissOwnerPrompt(preferences: PreferencesManager, sessionId: string): void {
+  const prefs = preferences.load()
+  if (prefs.ownerPromptDismissedSessionIds.includes(sessionId)) return
+  preferences.save({
+    ownerPromptDismissedSessionIds: [...prefs.ownerPromptDismissedSessionIds, sessionId],
+  })
+}
+
+/**
+ * Clear the owner of one session only. The platform profile is kept and may
+ * re-apply automatically later if it still uniquely matches.
+ */
+export function clearSessionOwner(adapter: SessionRuntimeAdapter, sessionId: string): void {
+  const db = adapter.ensureWritable(sessionId)
+  coreUpdateSessionOwnerId(db, null)
+}