Claude Code regularly sends each background agent’s transcript to its model

// no-agent-summary.js v2: Bun --preload hook that switches off Claude Code's `agent_summary` // side-query. Unofficial, not affiliated with Anthropic. Tested on Linux, Claude Code 2.1.301. // Install, env vars, verification and fail-open caveats: README.md. // // SPDX-License-Identifier: MIT // Copyright (c) 2026 Flamerix AI (https://flamerix.ai). Provided "as is", without warranty; // full license text: README.md. // // Anchors: the summarizer's debug-log line and its query-source id, both inside the timer // callback on 2.1.301. const IN_COMPILED_BUN = typeof Bun !== "undefined" && typeof Bun.main === "string" && Bun.main.startsWith("/$bunfs/"); function install() { const fs = require("fs"); const ANCHORS = ["[AgentSummary] Timer fired", "agent_summary"]; const RAW_MODE = process.env.CC_AGENT_SUMMARY_MODE || "off"; const MODE = RAW_MODE === "pass" ? "pass" : "off"; if (RAW_MODE !== MODE) process.stderr.write(`[no-agent-summary] unknown mode ${RAW_MODE}, forcing off\n`); const LOG = process.env.CC_AGENT_SUMMARY_LOG; const log = (s) => { if (LOG) { try { fs.appendFileSync(LOG, `${new Date().toISOString()} pid=${process.pid} ${s}\n`); } catch {} } }; const verdict = new WeakMap(); // fn -> bool (is the summary timer callback) function isSummaryTimer(fn) { if (typeof fn !== "function") return false; let v = verdict.get(fn); if (v === undefined) { try { const src = Function.prototype.toString.call(fn); v = ANCHORS.some((a) => src.includes(a)); } catch { v = false; } verdict.set(fn, v); } return v; } let matched = 0; let suppressed = 0; const PROMISIFY = Symbol.for("nodejs.util.promisify.custom"); const wrappers = new Map(); // original timer fn -> its wrapper: one wrapper per original const hookedFns = new WeakSet(); function wrap(orig, name) { if (typeof orig !== "function") return orig; if (wrappers.has(orig)) return wrappers.get(orig); const hooked = function (fn, delay, ...args) { if (isSummaryTimer(fn)) { matched++; if (MODE === "off") { suppressed++; if (matched <= 20) log(`summary timer #${matched} suppressed (${name}, delay=${delay})`); const t = orig(() => {}, 2 ** 31 - 1); // clear*-compatible handle of the same kind, never fires if (t && typeof t.unref === "function") t.unref(); return t; } if (matched <= 20) log(`summary timer #${matched} passed (control, ${name}, delay=${delay})`); } return orig(fn, delay, ...args); }; Object.defineProperty(hooked, "name", { value: name }); // util.promisify(setTimeout) reads these; without the custom one it calls the wrapper // callback-last and node throws ERR_INVALID_ARG_TYPE. if (orig.__promisify__) hooked.__promisify__ = orig.__promisify__; if (orig[PROMISIFY]) hooked[PROMISIFY] = orig[PROMISIFY]; wrappers.set(orig, hooked); hookedFns.add(hooked); return hooked; } // require("timers/promises").setTimeout(delay, value) takes no callback, so there is no source // to match an anchor in; it stays unwrapped. const timers = (() => { try { return require("timers"); } catch { return null; } })(); const hookedApis = []; for (const name of ["setTimeout", "setInterval"]) { globalThis[name] = wrap(globalThis[name], name); if (hookedFns.has(globalThis[name])) hookedApis.push(`global.${name}`); if (timers) { try { timers[name] = wrap(timers[name], name); } catch {} if (hookedFns.has(timers[name])) hookedApis.push(`timers.${name}`); } } const active = `preload active mode=${MODE} bun=${Bun.version} hooked=${hookedApis.join(",")}`; log(active); if (LOG) process.on("exit", () => log(`exit: ${suppressed} summary timer(s) suppressed, ${matched} matched`)); const MARKER = process.env.CC_AGENT_SUMMARY_MARKER; if (MARKER) { try { fs.writeFileSync(MARKER, `${active} pid=${process.pid}\n`); } catch (e) { process.stderr.write(`[no-agent-summary] cannot write marker ${MARKER}: ${e.message}\n`); } } } if (IN_COMPILED_BUN) install();