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fix: soft resync — recover a desynced world cache without losing agent state #796

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fix: soft resync — recover a desynced world cache without losing agent state #796

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151 changes: 100 additions & 51 deletions src/agent/agent.js
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Original file line number Diff line number Diff line change
Expand Up @@ -65,41 +65,8 @@ export class Agent {
console.log(this.name, 'logging into minecraft...');
this.bot = initBot(this.name);

// Connection Handler
const onDisconnect = (event, reason) => {
if (this._disconnectHandled) return;
this._disconnectHandled = true;

// Log and Analyze
// handleDisconnection handles logging to console and server
const { type } = handleDisconnection(this.name, reason);

process.exit(1);
};

// Bind events
this.bot.once('kicked', (reason) => onDisconnect('Kicked', reason));
this.bot.once('end', (reason) => onDisconnect('Disconnected', reason));
this.bot.on('error', (err) => {
if (String(err).includes('Duplicate') || String(err).includes('ECONNREFUSED')) {
onDisconnect('Error', err);
} else {
log(this.name, `[LoginGuard] Connection Error: ${String(err)}`);
}
});

this._bindConnectionHandlers();
initModes(this);

this.bot.on('login', () => {
console.log(this.name, 'logged in!');
serverProxy.login();

// Set skin for profile, requires Fabric Tailor. (https://modrinth.com/mod/fabrictailor)
if (this.prompter.profile.skin)
this.bot.chat(`/skin set URL ${this.prompter.profile.skin.model} ${this.prompter.profile.skin.path}`);
else
this.bot.chat(`/skin clear`);
});
const spawnTimeoutDuration = settings.spawn_timeout;
const spawnTimeout = setTimeout(() => {
const msg = `Bot has not spawned after ${spawnTimeoutDuration} seconds. Exiting.`;
Expand Down Expand Up @@ -144,7 +111,77 @@ export class Agent {
});
}

async _setupEventHandlers(save_data, init_message) {
// Bind connection-level handlers to the current bot. Called on the initial connect and again on a
// soft resync, so the disconnect/login logic lives in one place rather than being duplicated.
_bindConnectionHandlers() {
this._disconnectHandled = false;
this.bot.once('kicked', (reason) => this._onDisconnect('Kicked', reason));
this.bot.once('end', (reason) => this._onDisconnect('Disconnected', reason));
this.bot.on('error', (err) => {
if (String(err).includes('Duplicate') || String(err).includes('ECONNREFUSED'))
this._onDisconnect('Error', err);
else
log(this.name, `[LoginGuard] Connection Error: ${String(err)}`);
});
this.bot.on('login', () => {
console.log(this.name, 'logged in!');
serverProxy.login();
// Set skin for profile, requires Fabric Tailor. (https://modrinth.com/mod/fabrictailor)
if (this.prompter.profile.skin)
this.bot.chat(`/skin set URL ${this.prompter.profile.skin.model} ${this.prompter.profile.skin.path}`);
else
this.bot.chat(`/skin clear`);
});
}

_onDisconnect(event, reason) {
// A deliberate soft resync ends the old bot on purpose -- don't treat that as a crash.
if (this._disconnectHandled || this._reconnecting) return;
this._disconnectHandled = true;
handleDisconnection(this.name, reason);
process.exit(1);
}

// Reconnect the mineflayer bot in place to clear a desynced world cache (lag-induced ghost blocks:
// see PrismarineJS/mineflayer #2600). A fresh connection re-downloads chunks, fixing the corruption
// -- the same thing a full restart does, but WITHOUT killing the process, so the agent's history,
// memory and self-prompt goal survive. Falls back to cleanKill (a full restart) if it fails.
async softResync(reason = 'world cache desync') {
if (this._reconnecting) return false;
log(this.name, `Soft resync: reconnecting to refresh a desynced world cache (${reason}).`);
this.history.add('system', `(SYSTEM) Reconnected to clear a desynced world cache (${reason}); memory and goals preserved.`);
this._reconnecting = true;
try { this.actions.cancelResume(); } catch (e) {}
try { await this.actions.stop(); } catch (e) {} // await so the in-flight action actually stops before we swap the bot out
const old = this.bot;
try { old.removeAllListeners(); } catch (e) {}
try { old.quit('resync'); } catch (e) {}
await new Promise((r) => setTimeout(r, 2500));
this.bot = initBot(this.name);
this._bindConnectionHandlers();
initModes(this);
try {
await new Promise((resolve, reject) => {
const to = setTimeout(() => reject(new Error('spawn timeout')), (settings.spawn_timeout || 30) * 1000);
this.bot.once('spawn', async () => {
clearTimeout(to);
await new Promise((r) => setTimeout(r, 1000));
await this._setupEventHandlers(null, null, true); // isReconnect: skip greeting / memory reload
this.startEvents(); // re-attach the per-bot listeners; the update loop is started only once
resolve();
});
});
} catch (e) {
log(this.name, `Soft resync failed (${e.message}); falling back to restart.`);
this._reconnecting = false;
return this.cleanKill('Soft resync failed; restarting.', 4);
}
this._reconnecting = false;
log(this.name, 'Soft resync complete; world cache refreshed, agent state preserved.');
return true;
}

async _setupEventHandlers(save_data, init_message, isReconnect = false) {
const ignore_messages = [
"Set own game mode to",
"Set the time to",
Expand Down Expand Up @@ -194,6 +231,10 @@ export class Agent {
bannedFood: ["rotten_flesh", "spider_eye", "poisonous_potato", "pufferfish", "chicken"]
};

// On a soft resync the agent is already running -- skip the greeting / memory reload / task
// bootstrap so the bot quietly rejoins with its existing state intact.
if (isReconnect) return;

if (save_data?.self_prompt) {
if (init_message) {
this.history.add('system', init_message);
Expand Down Expand Up @@ -496,28 +537,36 @@ export class Agent {
}, 1000);
});

// Init NPC controller
this.npc.init();

// This update loop ensures that each update() is called one at a time, even if it takes longer than the interval
const INTERVAL = 300;
let last = Date.now();
setTimeout(async () => {
while (true) {
let start = Date.now();
await this.update(start - last);
let remaining = INTERVAL - (Date.now() - start);
if (remaining > 0) {
await new Promise((resolve) => setTimeout(resolve, remaining));
// The NPC controller and the update loop are process-global, not per-connection -- start them
// only once so a soft resync (which re-runs startEvents to rebind the bot listeners) does not
// spin up a second update loop.
if (!this._eventsInitialized) {
this._eventsInitialized = true;

// Init NPC controller
this.npc.init();

// This update loop ensures that each update() is called one at a time, even if it takes longer than the interval
const INTERVAL = 300;
let last = Date.now();
setTimeout(async () => {
while (true) {
let start = Date.now();
await this.update(start - last);
let remaining = INTERVAL - (Date.now() - start);
if (remaining > 0) {
await new Promise((resolve) => setTimeout(resolve, remaining));
}
last = start;
}
last = start;
}
}, INTERVAL);
}, INTERVAL);
}

this.bot.emit('idle');
}

async update(delta) {
if (this._reconnecting) return; // bot is being swapped out during a soft resync
await this.bot.modes.update();
this.self_prompter.update(delta);
await this.checkTaskDone();
Expand Down
5 changes: 4 additions & 1 deletion src/agent/commands/actions.js
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Original file line number Diff line number Diff line change
Expand Up @@ -284,8 +284,11 @@ export const actionsList = [
perform: runAsAction(async (agent, item_name, num) => {
let success = await skills.smeltItem(agent.bot, item_name, num);
if (success) {
// Smelting can leave mineflayer's inventory cache out of sync with the furnace output.
// Refresh it with a soft resync (reconnect in place) instead of a full process restart,
// so the agent keeps its history, goal and self-prompt loop.
setTimeout(() => {
agent.cleanKill('Safely restarting to update inventory.');
agent.softResync('refresh inventory after smelting');
}, 500);
}
})
Expand Down