feat(cli): use Claude Code session ID for mesh peer identity

claudemesh launch now generates a UUID and passes it to claude via
--session-id flag + CLAUDEMESH_SESSION_ID env var. The MCP server
reads this and sends it in the hello handshake.

Fallback: when launched without claudemesh launch (e.g., claude --resume),
detectClaudeSessionId() scans ~/.claude/projects/ for the most recent
.jsonl file and extracts the session UUID from the filename.

Benefits:
- Broker detects reconnections (same session = restore state)
- Multiple peers in same project dir get unique identities
- Session identity persists across --resume

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

apps/cli/package.json

@@ -1,6 +1,6 @@
 {
   "name": "claudemesh-cli",
-  "version": "0.8.1",
+  "version": "0.8.2",
   "description": "Claude Code MCP client for claudemesh — peer mesh messaging between Claude sessions.",
   "keywords": [
     "claude-code",

apps/cli/src/commands/launch.ts

@@ -14,6 +14,7 @@
  */
 
 import { spawn } from "node:child_process";
+import { randomUUID } from "node:crypto";
 import { mkdtempSync, writeFileSync, rmSync, readdirSync, statSync, existsSync, readFileSync } from "node:fs";
 import { tmpdir, hostname, homedir } from "node:os";
 import { join } from "node:path";
@@ -421,9 +422,16 @@ export async function runLaunch(flags: LaunchFlags, rawArgs: string[]): Promise<
   // passes -y / --yes. Without it, claudemesh tools still work because
   // `claudemesh install` pre-approves them via allowedTools in settings.json.
   // This keeps permissions tight for multi-person meshes.
+  // Generate a stable session ID for this launch. Used by the broker to:
+  // - detect reconnections (same session ID = restore state)
+  // - disambiguate multiple peers in the same project
+  // - persist identity across --resume (Claude reuses the session ID)
+  const claudeSessionId = randomUUID();
+
   const claudeArgs = [
     "--dangerously-load-development-channels",
     "server:claudemesh",
+    "--session-id", claudeSessionId,
     ...(args.skipPermConfirm ? ["--dangerously-skip-permissions"] : []),
     ...(args.systemPrompt ? ["--system-prompt", args.systemPrompt] : []),
     ...filtered,
@@ -437,6 +445,7 @@ export async function runLaunch(flags: LaunchFlags, rawArgs: string[]): Promise<
       ...process.env,
       CLAUDEMESH_CONFIG_DIR: tmpDir,
       CLAUDEMESH_DISPLAY_NAME: displayName,
+      CLAUDEMESH_SESSION_ID: claudeSessionId,
       MCP_TIMEOUT: process.env.MCP_TIMEOUT ?? "30000",
       MAX_MCP_OUTPUT_TOKENS: process.env.MAX_MCP_OUTPUT_TOKENS ?? "50000",
       ...(role ? { CLAUDEMESH_ROLE: role } : {}),

apps/cli/src/ws/client.ts

@@ -23,6 +23,43 @@ import {
 import { signHello } from "../crypto/hello-sig";
 import { generateKeypair } from "../crypto/keypair";
 
+/**
+ * Detect the Claude Code session ID from the filesystem.
+ * Fallback for when CLAUDEMESH_SESSION_ID env var isn't set
+ * (e.g., claude --resume without going through claudemesh launch).
+ *
+ * Scans ~/.claude/projects/<project-hash>/ for the most recently
+ * modified .jsonl file and extracts its sessionId.
+ */
+function detectClaudeSessionId(): string | null {
+  try {
+    const { readdirSync, statSync, readFileSync } = require("node:fs");
+    const { join } = require("node:path");
+    const { homedir } = require("node:os");
+    const cwd = process.cwd();
+    // Claude Code hashes the project path for the directory name
+    const projectsDir = join(homedir(), ".claude", "projects");
+    // Find matching project dir — the hash includes the full path with dashes
+    const cwdHash = cwd.replace(/\//g, "-");
+    const entries = readdirSync(projectsDir) as string[];
+    const projectDir = entries.find((e: string) => e === cwdHash || e.startsWith(cwdHash));
+    if (!projectDir) return null;
+
+    const fullDir = join(projectsDir, projectDir);
+    const jsonls = (readdirSync(fullDir) as string[])
+      .filter((f: string) => f.endsWith(".jsonl"))
+      .map((f: string) => ({ name: f, mtime: statSync(join(fullDir, f)).mtimeMs }))
+      .sort((a: any, b: any) => b.mtime - a.mtime);
+
+    if (jsonls.length === 0) return null;
+    const latest = jsonls[0]!;
+    // Session ID is the filename without .jsonl
+    return latest.name.replace(".jsonl", "");
+  } catch {
+    return null;
+  }
+}
+
 export type Priority = "now" | "next" | "low";
 export type ConnStatus = "connecting" | "open" | "closed" | "reconnecting";
 
@@ -194,7 +231,7 @@ export class BrokerClient {
               pubkey: this.mesh.pubkey,
               sessionPubkey: this.sessionPubkey,
               displayName: process.env.CLAUDEMESH_DISPLAY_NAME || this.opts.displayName || undefined,
-              sessionId: `${process.pid}-${Date.now()}`,
+              sessionId: process.env.CLAUDEMESH_SESSION_ID || detectClaudeSessionId() || `${process.pid}-${Date.now()}`,
               pid: process.pid,
               cwd: process.cwd(),
               hostname: require("os").hostname(),