fix(cli): drain TUI performance entries

.changeset/dispose-spawned-child-sessions.md

@@ -2,4 +2,4 @@
 "@runfusion/fusion": patch
 ---
 
-Dispose completed spawned child agent sessions so execution memory is released promptly after `fn_spawn_agent` children finish, keep artifact registry listing metadata-only so large inline artifacts are not loaded during agent execution, bound structured tool-result log previews and one-shot CLI output capture before serialization/parsing, and reduce dashboard SSE keepalive churn.
+Dispose completed spawned child agent sessions so execution memory is released promptly after `fn_spawn_agent` children finish, keep artifact registry listing metadata-only so large inline artifacts are not loaded during agent execution, bound structured tool-result log previews before serialization, reduce dashboard SSE keepalive churn, and keep the dashboard TUI performance timeline drained during long-running execution.

packages/cli/src/bin.ts

@@ -62,13 +62,15 @@ function configurePiPackage(): void {
 
 configurePiPackage();
 
-// Drain Node's User Timing buffer. Ink (react-reconciler) in dev mode emits
-// performance.mark()/measure() on every render; entries accumulate forever
-// without an observer, retaining ~600MB after 20-30min of TUI rendering.
+/*
+ * FNXC:DashboardTuiHeap 2026-06-23-12:08:
+ * Live heap profiling showed the dashboard TUI can allocate tens of thousands of React/Ink user-timing entries between renders, pushing server heap near 1GB before GC. Drain the performance timeline frequently so execution memory reflects active work instead of retained dev-mode render diagnostics.
+ */
 setInterval(() => {
   performance.clearMeasures();
   performance.clearMarks();
-}, 30_000).unref();
+  performance.clearResourceTimings();
+}, 1_000).unref();
 
 /**
  * Load `.env` (and `.env.local`) from the current working directory into

packages/cli/src/commands/dashboard-tui/app.tsx

@@ -18,6 +18,14 @@ function tuiDebug(tag: string, data: Record<string, unknown>): void {
   }
 }
 
+function drainTuiPerformanceTimeline(): void {
+  const perf = globalThis.performance;
+  if (!perf) return;
+  perf.clearMeasures?.();
+  perf.clearMarks?.();
+  perf.clearResourceTimings?.();
+}
+
 // Open a URL in the user's default browser. Uses the platform-native opener
 // (macOS `open`, Windows `start`, Linux `xdg-open`). Detached + ignored stdio
 // so the spawned process doesn't block the TUI's input loop.
@@ -4133,6 +4141,14 @@ export function DashboardApp({ controller }: DashboardAppProps) {
   const { exit } = useApp();
   const { stdout } = useStdout();
 
+  useEffect(() => {
+    /*
+     * FNXC:DashboardTuiHeap 2026-06-23-12:14:
+     * React/Ink development renders emit User Timing measures for every committed component. Clear them after each TUI commit so long-running execution does not retain render diagnostics in the dashboard server heap.
+     */
+    drainTuiPerformanceTimeline();
+  });
+
   // Bump a state counter on resize so React re-renders with the latest
   // dimensions. (The controller separately calls inkInstance.clear() to
   // reset Ink's log-update line tracking — manually writing clear escape

packages/engine/src/cli-agent/__tests__/one-shot-session.test.ts

@@ -13,7 +13,6 @@ import {
   extractJsonObjects,
   buildOneShotSettings,
   boundedStderrTail,
-  ONE_SHOT_OUTPUT_PARSE_CAP_BYTES,
   ONE_SHOT_STDERR_CAP_BYTES,
 } from "../one-shot-session.js";
 
@@ -251,27 +250,6 @@ describe("one-shot session lifecycle", () => {
     }
   });
 
-  it("retains only a bounded output tail while still parsing trailing JSON", async () => {
-    const h = newHarness(["codex"]);
-    const trailingJson = '{"text":"tail-ok"}';
-    const result = await runWith(
-      h,
-      "codex",
-      "validator",
-      `${"x".repeat(ONE_SHOT_OUTPUT_PARSE_CAP_BYTES + 1024)}\n${trailingJson}`,
-      0,
-    );
-
-    expect(result.ok).toBe(true);
-    if (result.ok) {
-      expect(Buffer.byteLength(result.rawOutput)).toBeLessThanOrEqual(
-        ONE_SHOT_OUTPUT_PARSE_CAP_BYTES,
-      );
-      expect(result.text).toBe("tail-ok");
-      expect(result.rawOutput).toContain(trailingJson);
-    }
-  });
-
   it("unparseable output → typed unparseable failure (never silent success)", async () => {
     const h = newHarness(["droid"]);
     const result = await runWith(h, "droid", "validator", "not json at all", 0);

packages/engine/src/cli-agent/one-shot-session.ts

@@ -36,43 +36,6 @@ import type { CliSessionManager } from "./session-manager.js";
 
 /** Maximum bytes of output retained for diagnostics on a failed one-shot. */
 export const ONE_SHOT_STDERR_CAP_BYTES = 8 * 1024;
-/*
- * FNXC:CliAgentHeap 2026-06-23-11:46:
- * One-shot sessions may run validators/tests that emit large terminal output. The terminal scrollback already gives users a bounded live view, so the result parser must retain only a bounded tail instead of buffering the full PTY stream in V8 heap until process exit.
- */
-export const ONE_SHOT_OUTPUT_PARSE_CAP_BYTES = 2 * 1024 * 1024;
-
-class BoundedOutputCollector {
-  private chunks: Buffer[] = [];
-  private size = 0;
-
-  append(chunk: Buffer): void {
-    if (chunk.byteLength === 0) return;
-    if (chunk.byteLength >= ONE_SHOT_OUTPUT_PARSE_CAP_BYTES) {
-      this.chunks = [chunk.subarray(chunk.byteLength - ONE_SHOT_OUTPUT_PARSE_CAP_BYTES)];
-      this.size = ONE_SHOT_OUTPUT_PARSE_CAP_BYTES;
-      return;
-    }
-
-    this.chunks.push(chunk);
-    this.size += chunk.byteLength;
-    while (this.size > ONE_SHOT_OUTPUT_PARSE_CAP_BYTES && this.chunks.length > 0) {
-      const overflow = this.size - ONE_SHOT_OUTPUT_PARSE_CAP_BYTES;
-      const head = this.chunks[0];
-      if (head.byteLength <= overflow) {
-        this.chunks.shift();
-        this.size -= head.byteLength;
-      } else {
-        this.chunks[0] = head.subarray(overflow);
-        this.size -= overflow;
-      }
-    }
-  }
-
-  toString(): string {
-    return Buffer.concat(this.chunks, this.size).toString("utf8");
-  }
-}
 
 // ── One-shot launch (non-interactive command builder) ───────────────────────
 
@@ -314,14 +277,14 @@ export async function runOneShotSession(opts: RunOneShotOptions): Promise<OneSho
 
   // Attach to collect output (also exercises the read-only terminal stream).
   const attachment = manager.attach(sessionId);
-  const output = new BoundedOutputCollector();
+  const chunks: Buffer[] = [];
   // Replay scrollback captured at attach (usually empty for a fresh spawn).
   if (attachment.scrollback.byteLength > 0) {
-    output.append(Buffer.from(attachment.scrollback));
+    chunks.push(Buffer.from(attachment.scrollback));
   }
   const drainPromise = (async () => {
     for await (const bytes of attachment.stream) {
-      output.append(Buffer.from(bytes));
+      chunks.push(Buffer.from(bytes));
     }
   })();
 
@@ -357,7 +320,7 @@ export async function runOneShotSession(opts: RunOneShotOptions): Promise<OneSho
   attachment.detach();
   await drainPromise.catch(() => undefined);
 
-  const rawOutput = output.toString();
+  const rawOutput = Buffer.concat(chunks).toString("utf8");
   const boundedTail = boundedStderrTail(rawOutput);
 
   if (exit.exitCode !== 0 || timedOut) {