feat(cli): add haqi worker refresh

SIGTERMs the worker in $HAPI_HOME/worker.lock, waits for it to exit, then
posts to the hub's /api/cloud/start-local-worker to respawn a fresh bun
process that re-reads the CLI source. Saves the kill + curl dance when
iterating on CLI code (e.g. picking up new RPC handlers without
restarting the whole dev stack).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jasonczc

cli/src/commands/worker.ts

@@ -1,4 +1,6 @@
 import chalk from 'chalk'
+import { existsSync, readFileSync } from 'node:fs'
+import { join } from 'node:path'
 import { configuration } from '@/configuration'
 import { startWorker } from '@/worker/workerStart'
 import { readWorkerConfig, clearWorkerConfig } from '@/worker/workerConfig'
@@ -19,6 +21,82 @@ function parseWorkerStartArgs(args: string[]): { token?: string; hubUrl?: string
     return { token, hubUrl }
 }
 
+function readWorkerLockPid(): number | null {
+    const lockFile = join(configuration.happyHomeDir, 'worker.lock')
+    if (!existsSync(lockFile)) return null
+    try {
+        const raw = readFileSync(lockFile, 'utf-8').trim()
+        const pid = Number.parseInt(raw, 10)
+        return Number.isFinite(pid) && pid > 0 ? pid : null
+    } catch {
+        return null
+    }
+}
+
+function isPidAlive(pid: number): boolean {
+    try {
+        process.kill(pid, 0)
+        return true
+    } catch {
+        return false
+    }
+}
+
+async function refreshWorker(): Promise<void> {
+    const pid = readWorkerLockPid()
+    if (pid && isPidAlive(pid)) {
+        console.log(chalk.gray(`Stopping current worker (pid ${pid})…`))
+        try {
+            process.kill(pid, 'SIGTERM')
+        } catch (err) {
+            console.error(chalk.red(`Failed to signal pid ${pid}: ${err instanceof Error ? err.message : String(err)}`))
+        }
+        // Wait for it to exit so its worker.lock is released before the hub spawns a replacement
+        for (let i = 0; i < 40; i++) {
+            if (!isPidAlive(pid)) break
+            await new Promise(r => setTimeout(r, 100))
+        }
+        if (isPidAlive(pid)) {
+            console.log(chalk.yellow(`Worker pid ${pid} still alive after 4s — hub will evict it via worker.lock`))
+        }
+    } else {
+        console.log(chalk.gray('No live worker detected from worker.lock — asking hub to spawn one…'))
+    }
+
+    if (!configuration.cliApiToken) {
+        throw new Error('CLI_API_TOKEN is not configured. Run `hapi auth login` first.')
+    }
+
+    const url = `${configuration.apiUrl.replace(/\/$/, '')}/api/cloud/start-local-worker`
+    const res = await fetch(url, {
+        method: 'POST',
+        headers: {
+            authorization: `Bearer ${configuration.cliApiToken}`,
+            'content-type': 'application/json',
+        },
+        body: '{}',
+    })
+
+    if (!res.ok) {
+        const text = await res.text().catch(() => '')
+        throw new Error(`Hub rejected request (${res.status}): ${text.slice(0, 400)}`)
+    }
+
+    const result = await res.json() as {
+        started?: boolean
+        pid?: number
+        alreadyRunning?: boolean
+        evictedPid?: number
+        startedAt?: number
+    }
+
+    const parts: string[] = []
+    if (result.pid) parts.push(`pid ${result.pid}`)
+    if (result.evictedPid) parts.push(`evicted ${result.evictedPid}`)
+    if (result.alreadyRunning) parts.push('already running')
+    console.log(chalk.green(`Worker refreshed${parts.length ? ` — ${parts.join(', ')}` : ''}`))
+}
+
 export const workerCommand: CommandDefinition = {
     name: 'worker',
     requiresRuntimeAssets: true,
@@ -60,6 +138,16 @@ export const workerCommand: CommandDefinition = {
             return
         }
 
+        if (subcommand === 'refresh') {
+            try {
+                await refreshWorker()
+            } catch (err) {
+                console.error(chalk.red('Error:'), err instanceof Error ? err.message : 'Unknown error')
+                process.exit(1)
+            }
+            return
+        }
+
         console.log(`
 ${chalk.bold('haqi worker')} - Self-hosted worker management
 
@@ -69,6 +157,8 @@ ${chalk.bold('Usage:')}
   haqi worker stop        Show instructions to stop the running worker
   haqi worker status      Display saved worker configuration
   haqi worker reset       Clear saved worker configuration
+  haqi worker refresh     Kill the local worker + ask the hub to respawn it
+                          (picks up updated CLI source without a full restart)
 
 ${chalk.bold('Notes:')}
   - The worker runs in the ${chalk.yellow('foreground')} (not detached).