detect existing .env and credentials on setup re-run

When re-running setup on a machine that already has a .env with
channel tokens or OneCLI config, detect them early and offer to
reuse instead of prompting the user to paste everything again.

- Add detectExistingEnv() to parse .env and group known keys
- Add detectExistingDisplayName() to read display name from v2.db
- Defer display name prompt until actually needed (cli-agent or channel)
- Skip cli-agent and first-chat when groups are already wired
- Add token reuse checks to Telegram, Discord, Slack, Teams, iMessage

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

setup/channels/discord.ts

@@ -239,6 +239,18 @@ async function walkThroughServerCreation(): Promise<void> {
 }
 
 async function collectDiscordToken(): Promise<string> {
+  const existing = process.env.DISCORD_BOT_TOKEN?.trim();
+  if (existing && /^[A-Za-z0-9._-]{50,}$/.test(existing)) {
+    const reuse = ensureAnswer(await p.confirm({
+      message: `Found an existing Discord bot token (${existing.slice(0, 10)}…). Use it?`,
+      initialValue: true,
+    }));
+    if (reuse) {
+      setupLog.userInput('discord_token', 'reused-existing');
+      return existing;
+    }
+  }
+
   const answer = ensureAnswer(
     await p.password({
       message: 'Paste your bot token',

setup/channels/imessage.ts

@@ -222,6 +222,19 @@ async function walkThroughFullDiskAccess(): Promise<void> {
 }
 
 async function collectRemoteCreds(): Promise<RemoteCreds> {
+  const existingUrl = process.env.IMESSAGE_SERVER_URL?.trim();
+  const existingKey = process.env.IMESSAGE_API_KEY?.trim();
+  if (existingUrl && existingKey && /^https?:\/\//i.test(existingUrl)) {
+    const reuse = ensureAnswer(await p.confirm({
+      message: `Found existing Photon credentials (${existingUrl}). Use them?`,
+      initialValue: true,
+    }));
+    if (reuse) {
+      setupLog.userInput('imessage_remote_creds', 'reused-existing');
+      return { serverUrl: existingUrl, apiKey: existingKey };
+    }
+  }
+
   p.note(
     [
       "Photon is a separate service that owns an iMessage account and",

setup/channels/slack.ts

@@ -151,6 +151,18 @@ async function walkThroughAppCreation(): Promise<void> {
 }
 
 async function collectBotToken(): Promise<string> {
+  const existing = process.env.SLACK_BOT_TOKEN?.trim();
+  if (existing && existing.startsWith('xoxb-') && existing.length >= 24) {
+    const reuse = ensureAnswer(await p.confirm({
+      message: `Found an existing Slack bot token (${existing.slice(0, 10)}…). Use it?`,
+      initialValue: true,
+    }));
+    if (reuse) {
+      setupLog.userInput('slack_bot_token', 'reused-existing');
+      return existing;
+    }
+  }
+
   const answer = ensureAnswer(
     await p.password({
       message: 'Paste your Slack bot token',
@@ -172,6 +184,18 @@ async function collectBotToken(): Promise<string> {
 }
 
 async function collectSigningSecret(): Promise<string> {
+  const existing = process.env.SLACK_SIGNING_SECRET?.trim();
+  if (existing && /^[a-f0-9]{16,}$/i.test(existing)) {
+    const reuse = ensureAnswer(await p.confirm({
+      message: 'Found an existing Slack signing secret. Use it?',
+      initialValue: true,
+    }));
+    if (reuse) {
+      setupLog.userInput('slack_signing_secret', 'reused-existing');
+      return existing;
+    }
+  }
+
   const answer = ensureAnswer(
     await p.password({
       message: 'Paste your Slack signing secret',

setup/channels/teams.ts

@@ -59,6 +59,28 @@ export async function runTeamsChannel(_displayName: string): Promise<void> {
   const collected: Collected = {};
   const completed: string[] = [];
 
+  const existingAppId = process.env.TEAMS_APP_ID?.trim();
+  const existingPassword = process.env.TEAMS_APP_PASSWORD?.trim();
+  if (existingAppId && existingPassword) {
+    const reuse = ensureAnswer(await p.confirm({
+      message: `Found existing Teams credentials (App ID: ${existingAppId.slice(0, 8)}…). Use them?`,
+      initialValue: true,
+    }));
+    if (reuse) {
+      collected.appId = existingAppId;
+      collected.appPassword = existingPassword;
+      collected.appType = (process.env.TEAMS_APP_TYPE?.trim() as 'SingleTenant' | 'MultiTenant') || 'MultiTenant';
+      if (collected.appType === 'SingleTenant') {
+        collected.tenantId = process.env.TEAMS_APP_TENANT_ID?.trim();
+      }
+      setupLog.userInput('teams_credentials', 'reused-existing');
+      await installAdapter(collected);
+      completed.push('Adapter installed and service restarted (reused existing credentials).');
+      await finishWithHandoff(collected, completed);
+      return;
+    }
+  }
+
   printIntro();
 
   await confirmPrereqs({ collected, completed });

setup/channels/telegram.ts

@@ -132,6 +132,18 @@ export async function runTelegramChannel(displayName: string): Promise<void> {
 }
 
 async function collectTelegramToken(): Promise<string> {
+  const existing = process.env.TELEGRAM_BOT_TOKEN?.trim();
+  if (existing && /^[0-9]+:[A-Za-z0-9_-]{35,}$/.test(existing)) {
+    const reuse = ensureAnswer(await p.confirm({
+      message: `Found an existing Telegram bot token (${existing.slice(0, 8)}…). Use it?`,
+      initialValue: true,
+    }));
+    if (reuse) {
+      setupLog.userInput('telegram_token', 'reused-existing');
+      return existing;
+    }
+  }
+
   p.note(
     [
       "Your assistant talks to you through a Telegram bot you create.",