feat(signal): auto-detect persistent storage for containerized deployments

Add setupSignalDataPersistence() to automatically symlink signal-cli
data directory to persistent storage when running in containers.

Priority order:
1. SIGNAL_CLI_DATA_DIR env var
2. /data/.local/share/signal-cli (Fly.io convention)
3. /var/lib/clawdbot/.local/share/signal-cli (alternative)
4. Default ~/.local/share/signal-cli (no symlink)

This ensures Signal account data survives container restarts without
requiring manual symlink setup or environment configuration.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/signal/daemon.ts

@@ -1,4 +1,7 @@
 import { spawn } from "node:child_process";
+import { existsSync, mkdirSync, symlinkSync, lstatSync } from "node:fs";
+import { homedir } from "node:os";
+import { join } from "node:path";
 import type { RuntimeEnv } from "../runtime.js";
 
 export type SignalDaemonOpts = {
@@ -18,6 +21,84 @@ export type SignalDaemonHandle = {
   stop: () => void;
 };
 
+/**
+ * Setup Signal data directory for containerized environments.
+ * Auto-detects persistent storage and creates symlink if needed.
+ *
+ * Priority order:
+ * 1. SIGNAL_CLI_DATA_DIR env var (if set)
+ * 2. /data/.local/share/signal-cli (Fly.io convention)
+ * 3. /var/lib/clawdbot/.local/share/signal-cli (alternative persistent location)
+ * 4. Default: ~/.local/share/signal-cli (no symlink needed)
+ */
+export function setupSignalDataPersistence(runtime?: RuntimeEnv): void {
+  const log = runtime?.log ?? (() => {});
+  const defaultPath = join(homedir(), ".local", "share", "signal-cli");
+
+  // Check if already a symlink or regular directory exists
+  if (existsSync(defaultPath)) {
+    try {
+      const stats = lstatSync(defaultPath);
+      if (stats.isSymbolicLink()) {
+        log(`signal-cli data already symlinked to persistent storage`);
+        return;
+      }
+      // Regular directory exists, don't touch it
+      return;
+    } catch {
+      // Ignore errors, will try to create below
+    }
+  }
+
+  // Determine persistent storage location
+  let persistentPath: string | null = null;
+
+  // Priority 1: Environment variable
+  if (process.env.SIGNAL_CLI_DATA_DIR) {
+    persistentPath = process.env.SIGNAL_CLI_DATA_DIR;
+    log(`signal-cli: using SIGNAL_CLI_DATA_DIR=${persistentPath}`);
+  }
+  // Priority 2: /data (Fly.io convention)
+  else if (existsSync("/data")) {
+    persistentPath = "/data/.local/share/signal-cli";
+  }
+  // Priority 3: /var/lib/clawdbot
+  else if (existsSync("/var/lib/clawdbot")) {
+    persistentPath = "/var/lib/clawdbot/.local/share/signal-cli";
+  }
+
+  // No persistent storage detected, use default
+  if (!persistentPath) {
+    return;
+  }
+
+  // Create persistent directory structure
+  try {
+    mkdirSync(persistentPath, { recursive: true });
+    mkdirSync(join(persistentPath, "data"), { recursive: true });
+  } catch (err) {
+    runtime?.error?.(`signal-cli: failed to create persistent directory: ${String(err)}`);
+    return;
+  }
+
+  // Create parent directory for symlink
+  try {
+    const parentDir = join(homedir(), ".local", "share");
+    mkdirSync(parentDir, { recursive: true });
+  } catch (err) {
+    runtime?.error?.(`signal-cli: failed to create parent directory: ${String(err)}`);
+    return;
+  }
+
+  // Create symlink
+  try {
+    symlinkSync(persistentPath, defaultPath);
+    log(`signal-cli: linked ${defaultPath} -> ${persistentPath} for persistence`);
+  } catch (err) {
+    runtime?.error?.(`signal-cli: failed to create symlink: ${String(err)}`);
+  }
+}
+
 export function classifySignalCliLogLine(line: string): "log" | "error" | null {
   const trimmed = line.trim();
   if (!trimmed) return null;
@@ -48,6 +129,9 @@ function buildDaemonArgs(opts: SignalDaemonOpts): string[] {
 }
 
 export function spawnSignalDaemon(opts: SignalDaemonOpts): SignalDaemonHandle {
+  // Setup persistent storage for containerized environments
+  setupSignalDataPersistence(opts.runtime);
+
   const args = buildDaemonArgs(opts);
   const child = spawn(opts.cliPath, args, {
     stdio: ["ignore", "pipe", "pipe"],