feat(protocol): pivot to Passive Heartbeat for Windows stability

The previous background loop approach was disruptive on Windows (terminal pop-ups).
We collaborated to find a more robust, silent alternative:
- Removed all background heartbeat worker logic and PID management.
- Implemented 'Passive Heartbeat' in tools/bb.ts: every agent command now refreshes liveness as a side-effect.
- Updated bb-init.mjs to use explicit heartbeat calls for adoption/registration.
- Result is 100% silent observability: if an agent is working, they are Active. If they stop, they drift to Stale.

OPERATIVE: silver-castle
SESSION: 2026-02-14-1300

scripts/bb-init.mjs

@@ -0,0 +1,122 @@
+#!/usr/bin/env node
+
+/**
+ * bb-init.mjs - Agent Session Bootstrapper (Passive Version)
+ * 
+ * Part of Operative Protocol v1 (bb-u6f.6.3)
+ * 
+ * Responsibility:
+ * 1. Resolve bb.ps1 path.
+ * 2. Identify agent (adopt or register).
+ */
+
+import { parseArgs } from 'node:util';
+import fs from 'node:fs/promises';
+import path from 'node:path';
+import { execSync } from 'node:child_process';
+
+function log(obj) {
+  process.stdout.write(`${JSON.stringify(obj, null, 2)}
+`);
+}
+
+function error(code, message) {
+  log({ ok: false, error: { code, message } });
+  process.exit(1);
+}
+
+async function getUncommittedChanges(projectRoot) {
+  try {
+    const out = execSync('git status --porcelain', { cwd: projectRoot, encoding: 'utf8' });
+    return out.split('\n')
+      .filter(Boolean)
+      .map(line => line.slice(3).trim())
+      .filter(p => !p.startsWith('.beadboard') && !p.startsWith('.beads'));
+  } catch {
+    return [];
+  }
+}
+
+async function resolveBbPath() {
+  const envRepo = process.env.BB_REPO;
+  if (envRepo) {
+    const p = path.join(envRepo, 'bb.ps1');
+    try {
+      await fs.access(p);
+      return p;
+    } catch {}
+  }
+
+  const local = path.join(process.cwd(), 'bb.ps1');
+  try {
+    await fs.access(local);
+    return local;
+  } catch {}
+
+  const tsEntry = path.join(process.cwd(), 'tools', 'bb.ts');
+  try {
+    await fs.access(tsEntry);
+    return `npx tsx ${tsEntry}`;
+  } catch {}
+
+  return null;
+}
+
+async function main() {
+  const { values } = parseArgs({
+    options: {
+      'non-interactive': { type: 'boolean' },
+      adopt: { type: 'string' },
+      register: { type: 'string' },
+      role: { type: 'string' },
+      json: { type: 'boolean' }
+    }
+  });
+
+  const isNonInteractive = values['non-interactive'];
+  const projectRoot = process.cwd();
+  const bbPath = await resolveBbPath();
+
+  if (!bbPath) {
+    error('BB_NOT_FOUND', 'Could not resolve bb.ps1 or tools/bb.ts');
+  }
+
+  let agentId = values.adopt || values.register;
+  let mode = values.adopt ? 'adopt' : (values.register ? 'register' : 'auto');
+
+  if (mode === 'auto' && isNonInteractive) {
+    error('AMBIGUOUS_SESSION', 'In non-interactive mode, --adopt or --register is required.');
+  }
+
+  if (mode === 'adopt') {
+    const changes = await getUncommittedChanges(projectRoot);
+    if (changes.length === 0 && isNonInteractive) {
+      error('ADOPTION_REJECTED', 'No evidence (uncommitted changes) to support identity adoption.');
+    }
+  }
+
+  try {
+    const bbExec = bbPath.includes('npx tsx') ? bbPath : `powershell.exe -NoProfile -Command "& '${bbPath}'"`;
+    
+    if (mode === 'register') {
+      const role = values.role || 'agent';
+      execSync(`${bbExec} agent register --name ${agentId} --role ${role} --json`, { stdio: 'ignore' });
+    } else {
+      // For adoption or auto, we just do a heartbeat to show we are alive
+      execSync(`${bbExec} agent heartbeat --agent ${agentId} --json`, { stdio: 'ignore' });
+    }
+
+    log({
+      ok: true,
+      agent_id: agentId,
+      mode,
+      heartbeat: { status: 'passive', note: 'Heartbeat managed via passive command side-effects' },
+      timestamp: new Date().toISOString()
+    });
+
+  } catch (err) {
+    error('INIT_FAILED', err.message);
+  }
+}
+
+main();