diff --git a/src/proxy/proxy-daemon-paths.ts b/src/proxy/proxy-daemon-paths.ts
index 011a9f59..7119c2e9 100644
--- a/src/proxy/proxy-daemon-paths.ts
+++ b/src/proxy/proxy-daemon-paths.ts
@@ -25,3 +25,11 @@ export function getOpenAICompatProxySessionPath(profileName: string): string {
     `${getOpenAICompatProxyProfileKey(profileName)}.session.json`
   );
 }
+
+export function getLegacyOpenAICompatProxyPidPath(): string {
+  return path.join(getOpenAICompatProxyDir(), 'daemon.pid');
+}
+
+export function getLegacyOpenAICompatProxySessionPath(): string {
+  return path.join(getOpenAICompatProxyDir(), 'session.json');
+}
diff --git a/src/proxy/proxy-daemon-state.ts b/src/proxy/proxy-daemon-state.ts
index 82d11130..98899e47 100644
--- a/src/proxy/proxy-daemon-state.ts
+++ b/src/proxy/proxy-daemon-state.ts
@@ -2,6 +2,8 @@ import * as fs from 'fs';
 import * as path from 'path';
 import {
   getOpenAICompatProxyDir,
+  getLegacyOpenAICompatProxyPidPath,
+  getLegacyOpenAICompatProxySessionPath,
   getOpenAICompatProxyPidPath,
   getOpenAICompatProxySessionPath,
 } from './proxy-daemon-paths';
@@ -21,9 +23,9 @@ function ensureProxyDir(): void {
   fs.mkdirSync(getOpenAICompatProxyDir(), { recursive: true });
 }
 
-export function getOpenAICompatProxyPid(profileName: string): number | null {
+function readPid(pidPath: string): number | null {
   try {
-    const raw = fs.readFileSync(getOpenAICompatProxyPidPath(profileName), 'utf8').trim();
+    const raw = fs.readFileSync(pidPath, 'utf8').trim();
     const pid = Number.parseInt(raw, 10);
     return Number.isInteger(pid) ? pid : null;
   } catch {
@@ -31,6 +33,14 @@ export function getOpenAICompatProxyPid(profileName: string): number | null {
   }
 }
 
+export function getOpenAICompatProxyPid(profileName: string): number | null {
+  return readPid(getOpenAICompatProxyPidPath(profileName));
+}
+
+export function getLegacyOpenAICompatProxyPid(): number | null {
+  return readPid(getLegacyOpenAICompatProxyPidPath());
+}
+
 export function writeOpenAICompatProxyPid(profileName: string, pid: number): void {
   ensureProxyDir();
   fs.writeFileSync(getOpenAICompatProxyPidPath(profileName), String(pid), 'utf8');
@@ -44,16 +54,30 @@ export function removeOpenAICompatProxyPid(profileName: string): void {
   }
 }
 
-export function readOpenAICompatProxySession(profileName: string): OpenAICompatProxySession | null {
+export function removeLegacyOpenAICompatProxyPid(): void {
   try {
-    return JSON.parse(
-      fs.readFileSync(getOpenAICompatProxySessionPath(profileName), 'utf8')
-    ) as OpenAICompatProxySession;
+    fs.unlinkSync(getLegacyOpenAICompatProxyPidPath());
+  } catch {
+    // Best-effort cleanup.
+  }
+}
+
+function readSession(sessionPath: string): OpenAICompatProxySession | null {
+  try {
+    return JSON.parse(fs.readFileSync(sessionPath, 'utf8')) as OpenAICompatProxySession;
   } catch {
     return null;
   }
 }
 
+export function readOpenAICompatProxySession(profileName: string): OpenAICompatProxySession | null {
+  return readSession(getOpenAICompatProxySessionPath(profileName));
+}
+
+export function readLegacyOpenAICompatProxySession(): OpenAICompatProxySession | null {
+  return readSession(getLegacyOpenAICompatProxySessionPath());
+}
+
 export function writeOpenAICompatProxySession(session: OpenAICompatProxySession): void {
   ensureProxyDir();
   fs.writeFileSync(
@@ -71,6 +95,14 @@ export function removeOpenAICompatProxySession(profileName: string): void {
   }
 }
 
+export function removeLegacyOpenAICompatProxySession(): void {
+  try {
+    fs.unlinkSync(getLegacyOpenAICompatProxySessionPath());
+  } catch {
+    // Best-effort cleanup.
+  }
+}
+
 export function listOpenAICompatProxyProfileNames(): string[] {
   try {
     const entries = fs.readdirSync(getOpenAICompatProxyDir(), { withFileTypes: true });
@@ -87,18 +119,6 @@ export function listOpenAICompatProxyProfileNames(): string[] {
   }
 }
 
-export function cleanupLegacyOpenAICompatProxyState(): void {
-  ensureProxyDir();
-  const legacyNames = ['daemon.pid', 'session.json'];
-  for (const legacyName of legacyNames) {
-    try {
-      fs.unlinkSync(path.join(getOpenAICompatProxyDir(), legacyName));
-    } catch {
-      // Best-effort cleanup.
-    }
-  }
-}
-
 export function resolveOpenAICompatProxyEntrypointCandidates(): string[] {
   const jsEntry = path.join(__dirname, 'proxy-daemon-entry.js');
   const tsEntry = path.join(__dirname, 'proxy-daemon-entry.ts');
diff --git a/src/proxy/proxy-daemon.ts b/src/proxy/proxy-daemon.ts
index ac3f3599..d26c8e3c 100644
--- a/src/proxy/proxy-daemon.ts
+++ b/src/proxy/proxy-daemon.ts
@@ -12,10 +12,13 @@ import {
   getOpenAICompatProxyDir,
 } from './proxy-daemon-paths';
 import {
+  getLegacyOpenAICompatProxyPid,
   getOpenAICompatProxyPid,
   listOpenAICompatProxyProfileNames,
+  readLegacyOpenAICompatProxySession,
   readOpenAICompatProxySession,
-  cleanupLegacyOpenAICompatProxyState,
+  removeLegacyOpenAICompatProxyPid,
+  removeLegacyOpenAICompatProxySession,
   removeOpenAICompatProxyPid,
   removeOpenAICompatProxySession,
   resolveOpenAICompatProxyEntrypointCandidates,
@@ -23,7 +26,7 @@ import {
   writeOpenAICompatProxyPid,
   writeOpenAICompatProxySession,
 } from './proxy-daemon-state';
-import { resolveOpenAICompatProxyPreferredPort } from './proxy-port-resolver';
+import { resolveOpenAICompatProxyPortPreference } from './proxy-port-resolver';
 
 export interface OpenAICompatProxyStatus extends Partial<OpenAICompatProxySession> {
   running: boolean;
@@ -111,6 +114,12 @@ async function findOpenAICompatProxyPortNear(preferredPort: number): Promise<num
   return findOpenAICompatProxyPort();
 }
 
+interface OpenAICompatProxyStateRecord {
+  pid: number | null;
+  session: OpenAICompatProxySession | null;
+  source: 'profile' | 'legacy';
+}
+
 async function resolveDaemonEntrypoint(): Promise<string | null> {
   for (const candidate of resolveOpenAICompatProxyEntrypointCandidates()) {
     try {
@@ -157,20 +166,51 @@ export async function isOpenAICompatProxyRunning(port: number): Promise<boolean>
 async function getOpenAICompatProxyStatusForProfile(
   profileName: string
 ): Promise<OpenAICompatProxyStatus> {
-  const session = readOpenAICompatProxySession(profileName);
-  const port = session?.port ?? OPENAI_COMPAT_PROXY_DEFAULT_PORT;
+  const state = getOpenAICompatProxyStateForProfile(profileName);
+  const session = state.session;
+  if (!session) {
+    return { running: false };
+  }
+
+  const port = session.port;
   const running = await isOpenAICompatProxyRunning(port);
   return {
     running,
-    pid: running ? getOpenAICompatProxyPid(profileName) || undefined : undefined,
+    pid: running ? state.pid || undefined : undefined,
     ...session,
   };
 }
 
+function getOpenAICompatProxyStateForProfile(profileName: string): OpenAICompatProxyStateRecord {
+  const session = readOpenAICompatProxySession(profileName);
+  if (session) {
+    return {
+      pid: getOpenAICompatProxyPid(profileName),
+      session,
+      source: 'profile',
+    };
+  }
+
+  const legacySession = readLegacyOpenAICompatProxySession();
+  if (legacySession?.profileName === profileName) {
+    return {
+      pid: getLegacyOpenAICompatProxyPid(),
+      session: legacySession,
+      source: 'legacy',
+    };
+  }
+
+  return { pid: null, session: null, source: 'profile' };
+}
+
 export async function listOpenAICompatProxyStatuses(): Promise<OpenAICompatProxyStatus[]> {
-  const profileNames = listOpenAICompatProxyProfileNames();
+  const profileNames = new Set(listOpenAICompatProxyProfileNames());
+  const legacySession = readLegacyOpenAICompatProxySession();
+  if (legacySession?.profileName) {
+    profileNames.add(legacySession.profileName);
+  }
   const statuses = await Promise.all(
-    profileNames.map((profileName) => getOpenAICompatProxyStatusForProfile(profileName))
+    [...profileNames].map((profileName) => getOpenAICompatProxyStatusForProfile(profileName))
   );
   return statuses.filter((status) => status.profileName);
 }
@@ -197,9 +237,10 @@ export async function getOpenAICompatProxyStatus(
 async function stopOpenAICompatProxyUnlocked(
   profileName: string
 ): Promise<{ success: boolean; error?: string }> {
-  const pid = getOpenAICompatProxyPid(profileName);
+  const state = getOpenAICompatProxyStateForProfile(profileName);
+  const pid = state.pid;
   if (!pid) {
-    removeOpenAICompatProxySession(profileName);
+    removeOpenAICompatProxyState(state, profileName);
     return { success: true };
   }
 
@@ -211,8 +252,7 @@ async function stopOpenAICompatProxyUnlocked(
   );
 
   if (ownership === 'not-owned') {
-    removeOpenAICompatProxyPid(profileName);
-    removeOpenAICompatProxySession(profileName);
+    removeOpenAICompatProxyState(state, profileName);
     return { success: true };
   }
 
@@ -224,8 +264,7 @@ async function stopOpenAICompatProxyUnlocked(
   }
 
   if (ownership === 'not-running') {
-    removeOpenAICompatProxyPid(profileName);
-    removeOpenAICompatProxySession(profileName);
+    removeOpenAICompatProxyState(state, profileName);
     return { success: true };
   }
 
@@ -256,16 +295,28 @@ async function stopOpenAICompatProxyUnlocked(
     }
   }
 
+  removeOpenAICompatProxyState(state, profileName);
+  return { success: true };
+}
+
+function removeOpenAICompatProxyState(
+  state: OpenAICompatProxyStateRecord,
+  profileName: string
+): void {
+  if (state.source === 'legacy') {
+    removeLegacyOpenAICompatProxyPid();
+    removeLegacyOpenAICompatProxySession();
+    return;
+  }
+
   removeOpenAICompatProxyPid(profileName);
   removeOpenAICompatProxySession(profileName);
-  return { success: true };
 }
 
 export async function stopOpenAICompatProxy(
   profileName?: string
 ): Promise<{ success: boolean; error?: string }> {
   return withOpenAICompatProxyLock(async () => {
-    cleanupLegacyOpenAICompatProxyState();
     if (profileName) {
       return stopOpenAICompatProxyUnlocked(profileName);
     }
@@ -289,17 +340,22 @@ export async function startOpenAICompatProxy(
   options: { port?: number; host?: string; insecure?: boolean } = {}
 ): Promise<StartOpenAICompatProxyResult> {
   return withOpenAICompatProxyLock(async () => {
-    cleanupLegacyOpenAICompatProxyState();
     const status = await getOpenAICompatProxyStatus(profile.profileName);
     const host = options.host?.trim() || status.host || '127.0.0.1';
+    const portPreference = resolveOpenAICompatProxyPortPreference(profile.profileName);
+    const explicitPort = typeof options.port === 'number' ? options.port : undefined;
     const preferredPort =
-      typeof options.port === 'number'
-        ? options.port
-        : status.port || resolveOpenAICompatProxyPreferredPort(profile.profileName);
+      explicitPort ??
+      (portPreference.source === 'profile'
+        ? portPreference.port
+        : status.port || portPreference.port);
+    const requiresExactPort = explicitPort !== undefined || portPreference.source === 'profile';
     const port =
       status.running && status.port && (status.host || '127.0.0.1') === host
         ? status.port
-        : await findOpenAICompatProxyPortNear(preferredPort);
+        : requiresExactPort
+          ? preferredPort
+          : await findOpenAICompatProxyPortNear(preferredPort);
     if (port === 0) {
       return {
         success: false,
@@ -319,6 +375,13 @@ export async function startOpenAICompatProxy(
         authToken: status.authToken,
       };
     }
+    if (requiresExactPort && (await isPortOccupied(port))) {
+      return {
+        success: false,
+        port,
+        error: `Requested proxy port ${port} is already in use`,
+      };
+    }
     if (status.running) {
       const stopped = await stopOpenAICompatProxyUnlocked(profile.profileName);
       if (!stopped.success) {
diff --git a/src/proxy/proxy-port-resolver.ts b/src/proxy/proxy-port-resolver.ts
index 919e5755..418ca721 100644
--- a/src/proxy/proxy-port-resolver.ts
+++ b/src/proxy/proxy-port-resolver.ts
@@ -1,11 +1,25 @@
 import { loadOrCreateUnifiedConfig } from '../config/unified-config-loader';
 import { OPENAI_COMPAT_PROXY_DEFAULT_PORT } from './proxy-daemon-paths';
 
-export function resolveOpenAICompatProxyPreferredPort(profileName: string): number {
+export interface OpenAICompatProxyPortPreference {
+  port: number;
+  source: 'default' | 'profile';
+}
+
+export function resolveOpenAICompatProxyPortPreference(
+  profileName: string
+): OpenAICompatProxyPortPreference {
   const config = loadOrCreateUnifiedConfig();
   const profilePort = config.proxy?.profile_ports?.[profileName];
   if (typeof profilePort === 'number') {
-    return profilePort;
+    return { port: profilePort, source: 'profile' };
   }
-  return config.proxy?.port ?? OPENAI_COMPAT_PROXY_DEFAULT_PORT;
+  return {
+    port: config.proxy?.port ?? OPENAI_COMPAT_PROXY_DEFAULT_PORT,
+    source: 'default',
+  };
+}
+
+export function resolveOpenAICompatProxyPreferredPort(profileName: string): number {
+  return resolveOpenAICompatProxyPortPreference(profileName).port;
 }
diff --git a/tests/integration/proxy/daemon-lifecycle.test.ts b/tests/integration/proxy/daemon-lifecycle.test.ts
index f6cb8e63..9ff9e5f6 100644
--- a/tests/integration/proxy/daemon-lifecycle.test.ts
+++ b/tests/integration/proxy/daemon-lifecycle.test.ts
@@ -9,6 +9,11 @@ import {
   stopOpenAICompatProxy,
 } from '../../../src/proxy/proxy-daemon';
 import { resolveOpenAICompatProfileConfig } from '../../../src/proxy/profile-router';
+import {
+  getLegacyOpenAICompatProxyPidPath,
+  getLegacyOpenAICompatProxySessionPath,
+} from '../../../src/proxy/proxy-daemon-paths';
+import { mutateUnifiedConfig } from '../../../src/config/unified-config-loader';
 
 let originalCcsHome: string | undefined;
 let tempDir: string;
@@ -140,4 +145,162 @@ describe('openai proxy daemon lifecycle', () => {
     const secondHealth = await fetch(`http://127.0.0.1:${secondPort}/health`);
     expect(secondHealth.status).toBe(200);
   });
+
+  it('keeps a legacy singleton daemon visible across upgrade', async () => {
+    const port = await getPort();
+    const settingsPath = path.join(tempDir, 'legacy.settings.json');
+    fs.writeFileSync(
+      settingsPath,
+      JSON.stringify({
+        env: {
+          ANTHROPIC_BASE_URL: 'http://127.0.0.1:11434',
+          ANTHROPIC_AUTH_TOKEN: 'ollama-legacy',
+          ANTHROPIC_MODEL: 'qwen3-coder',
+          CCS_DROID_PROVIDER: 'generic-chat-completion-api',
+        },
+      }),
+      'utf8'
+    );
+
+    const profile = resolveOpenAICompatProfileConfig('legacy', settingsPath, {
+      ANTHROPIC_BASE_URL: 'http://127.0.0.1:11434',
+      ANTHROPIC_AUTH_TOKEN: 'ollama-legacy',
+      ANTHROPIC_MODEL: 'qwen3-coder',
+      CCS_DROID_PROVIDER: 'generic-chat-completion-api',
+    });
+    if (!profile) {
+      throw new Error('Expected a legacy OpenAI-compatible profile');
+    }
+
+    const started = await startOpenAICompatProxy(profile, { port });
+    expect(started.success).toBe(true);
+    expect(started.pid).toBeDefined();
+
+    const proxyDir = path.dirname(getLegacyOpenAICompatProxyPidPath());
+    fs.writeFileSync(getLegacyOpenAICompatProxyPidPath(), String(started.pid), 'utf8');
+    fs.writeFileSync(
+      getLegacyOpenAICompatProxySessionPath(),
+      JSON.stringify(
+        {
+          profileName: profile.profileName,
+          settingsPath: profile.settingsPath,
+          host: '127.0.0.1',
+          port,
+          baseUrl: profile.baseUrl,
+          authToken: started.authToken,
+          model: profile.model,
+        },
+        null,
+        2
+      ) + '\n',
+      'utf8'
+    );
+    fs.rmSync(path.join(proxyDir, 'legacy.daemon.pid'), { force: true });
+    fs.rmSync(path.join(proxyDir, 'legacy.session.json'), { force: true });
+
+    const status = await getOpenAICompatProxyStatus('legacy');
+    expect(status.running).toBe(true);
+    expect(status.port).toBe(port);
+
+    const restarted = await startOpenAICompatProxy(profile);
+    expect(restarted.success).toBe(true);
+    expect(restarted.alreadyRunning).toBe(true);
+    expect(restarted.port).toBe(port);
+
+    const stopped = await stopOpenAICompatProxy('legacy');
+    expect(stopped.success).toBe(true);
+    expect(fs.existsSync(getLegacyOpenAICompatProxyPidPath())).toBe(false);
+    expect(fs.existsSync(getLegacyOpenAICompatProxySessionPath())).toBe(false);
+  }, 35000);
+
+  it('fails when an explicit port is already occupied', async () => {
+    const occupiedPort = await getPort();
+    const server = Bun.serve({
+      port: occupiedPort,
+      hostname: '127.0.0.1',
+      fetch: () => new Response('busy'),
+    });
+
+    try {
+      const settingsPath = path.join(tempDir, 'occupied-explicit.settings.json');
+      fs.writeFileSync(
+        settingsPath,
+        JSON.stringify({
+          env: {
+            ANTHROPIC_BASE_URL: 'http://127.0.0.1:11434',
+            ANTHROPIC_AUTH_TOKEN: 'ollama-explicit',
+            ANTHROPIC_MODEL: 'qwen3-coder',
+            CCS_DROID_PROVIDER: 'generic-chat-completion-api',
+          },
+        }),
+        'utf8'
+      );
+
+      const profile = resolveOpenAICompatProfileConfig('explicit', settingsPath, {
+        ANTHROPIC_BASE_URL: 'http://127.0.0.1:11434',
+        ANTHROPIC_AUTH_TOKEN: 'ollama-explicit',
+        ANTHROPIC_MODEL: 'qwen3-coder',
+        CCS_DROID_PROVIDER: 'generic-chat-completion-api',
+      });
+      if (!profile) {
+        throw new Error('Expected an explicit-port OpenAI-compatible profile');
+      }
+
+      const started = await startOpenAICompatProxy(profile, { port: occupiedPort });
+      expect(started.success).toBe(false);
+      expect(started.port).toBe(occupiedPort);
+      expect(started.error).toContain(`Requested proxy port ${occupiedPort} is already in use`);
+    } finally {
+      server.stop(true);
+    }
+  });
+
+  it('fails when a configured profile port is already occupied', async () => {
+    const occupiedPort = await getPort();
+    const server = Bun.serve({
+      port: occupiedPort,
+      hostname: '127.0.0.1',
+      fetch: () => new Response('busy'),
+    });
+
+    try {
+      mutateUnifiedConfig((config) => {
+        config.proxy = {
+          ...(config.proxy ?? {}),
+          profile_ports: { mapped: occupiedPort },
+        };
+      });
+
+      const settingsPath = path.join(tempDir, 'occupied-mapped.settings.json');
+      fs.writeFileSync(
+        settingsPath,
+        JSON.stringify({
+          env: {
+            ANTHROPIC_BASE_URL: 'http://127.0.0.1:11434',
+            ANTHROPIC_AUTH_TOKEN: 'ollama-mapped',
+            ANTHROPIC_MODEL: 'qwen3-coder',
+            CCS_DROID_PROVIDER: 'generic-chat-completion-api',
+          },
+        }),
+        'utf8'
+      );
+
+      const profile = resolveOpenAICompatProfileConfig('mapped', settingsPath, {
+        ANTHROPIC_BASE_URL: 'http://127.0.0.1:11434',
+        ANTHROPIC_AUTH_TOKEN: 'ollama-mapped',
+        ANTHROPIC_MODEL: 'qwen3-coder',
+        CCS_DROID_PROVIDER: 'generic-chat-completion-api',
+      });
+      if (!profile) {
+        throw new Error('Expected a mapped-port OpenAI-compatible profile');
+      }
+
+      const started = await startOpenAICompatProxy(profile);
+      expect(started.success).toBe(false);
+      expect(started.port).toBe(occupiedPort);
+      expect(started.error).toContain(`Requested proxy port ${occupiedPort} is already in use`);
+    } finally {
+      server.stop(true);
+    }
+  });
 });