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fix: prevent spurious sandbox restarts under concurrent agent usage #31

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Merged
malaporte merged 1 commit into from
Apr 10, 2026
Merged

fix: prevent spurious sandbox restarts under concurrent agent usage #31

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47 changes: 33 additions & 14 deletions src/cli/sandbox.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -50,27 +50,47 @@ export async function ensureSandbox(
sandboxName: string,
sandboxConfig: SandboxConfig,
): Promise<number> {
// Fast path: if a healthy sandbox exists and the hash matches, return immediately
// without acquiring the lock. This is the common case for concurrent agents.
const existing = await validateState(sandboxName)
if (existing) {
if (existing.configHash) {
const globalConfig = readGlobalConfig()
const currentHash = await computeConfigHash(sandboxConfig, globalConfig)

if (existing.configHash === currentHash) {
return existing.port
}

process.stderr.write('pippin: sandbox configuration changed, restarting...\n')
await stopSandbox(sandboxName)
} else {
if (existing?.configHash) {
const globalConfig = readGlobalConfig()
const currentHash = await computeConfigHash(sandboxConfig, globalConfig)
if (existing.configHash === currentHash) {
return existing.port
}
} else if (existing && !existing.configHash) {
// Legacy state with no hash — reuse blindly (same behaviour as before)
return existing.port
}

// Slow path: sandbox is missing or config changed. Acquire the lock so that
// only one agent performs the stop+start cycle at a time. Other agents will
// wait via waitForSandbox and pick up the freshly written state.
const MAX_LOCK_ATTEMPTS = 3
for (let attempt = 0; attempt < MAX_LOCK_ATTEMPTS; attempt++) {
if (acquireLock(sandboxName)) {
try {
// Re-validate inside the lock: another agent may have already restarted
// the sandbox while we were waiting to acquire the lock.
const recheck = await validateState(sandboxName)
if (recheck?.configHash) {
const globalConfig = readGlobalConfig()
const currentHash = await computeConfigHash(sandboxConfig, globalConfig)
if (recheck.configHash === currentHash) {
return recheck.port
}
} else if (recheck && !recheck.configHash) {
return recheck.port
}

// Config still mismatched (or sandbox gone) — stop and restart.
const stale = await validateState(sandboxName)
if (stale) {
process.stderr.write('pippin: sandbox configuration changed, restarting...\n')
await stopSandbox(sandboxName)
}

return await startSandbox(sandboxName, sandboxConfig)
} finally {
releaseLock(sandboxName)
Expand Down Expand Up @@ -867,12 +887,11 @@ export function resolveGpgSocketInfo(containerHome: string): GpgSocketInfo | nul
const hostSocket = result.stdout?.trim()
if (result.status !== 0 || !hostSocket || !fs.existsSync(hostSocket)) continue

const stat = fs.lstatSync(hostSocket)
return {
hostSocket,
containerSocket: `${containerHome}/.gnupg/S.gpg-agent`,
source: dir,
fingerprint: `${dir}:${hostSocket}:${stat.ino}:${Math.trunc(stat.mtimeMs)}`,
fingerprint: `${dir}:${hostSocket}`,
}
} catch {
continue
Expand Down
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