fix: cap pending process output

src/agents/bash-process-registry.test.ts

@@ -4,6 +4,7 @@ import type { ProcessSession } from "./bash-process-registry.js";
 import {
   addSession,
   appendOutput,
+  drainSession,
   listFinishedSessions,
   markBackgrounded,
   markExited,
@@ -23,9 +24,12 @@ describe("bash process registry", () => {
       startedAt: Date.now(),
       cwd: "/tmp",
       maxOutputChars: 10,
+      pendingMaxOutputChars: 30_000,
       totalOutputChars: 0,
       pendingStdout: [],
       pendingStderr: [],
+      pendingStdoutChars: 0,
+      pendingStderrChars: 0,
       aggregated: "",
       tail: "",
       exited: false,
@@ -43,6 +47,105 @@ describe("bash process registry", () => {
     expect(session.truncated).toBe(true);
   });
 
+  it("caps pending output to avoid runaway polls", () => {
+    const session: ProcessSession = {
+      id: "sess",
+      command: "echo test",
+      child: { pid: 123 } as ChildProcessWithoutNullStreams,
+      startedAt: Date.now(),
+      cwd: "/tmp",
+      maxOutputChars: 100_000,
+      pendingMaxOutputChars: 20_000,
+      totalOutputChars: 0,
+      pendingStdout: [],
+      pendingStderr: [],
+      pendingStdoutChars: 0,
+      pendingStderrChars: 0,
+      aggregated: "",
+      tail: "",
+      exited: false,
+      exitCode: undefined,
+      exitSignal: undefined,
+      truncated: false,
+      backgrounded: true,
+    };
+
+    addSession(session);
+    const payload = `${"a".repeat(70_000)}${"b".repeat(20_000)}`;
+    appendOutput(session, "stdout", payload);
+
+    const drained = drainSession(session);
+    expect(drained.stdout).toBe("b".repeat(20_000));
+    expect(session.pendingStdout).toHaveLength(0);
+    expect(session.pendingStdoutChars).toBe(0);
+    expect(session.truncated).toBe(true);
+  });
+
+  it("respects max output cap when pending cap is larger", () => {
+    const session: ProcessSession = {
+      id: "sess",
+      command: "echo test",
+      child: { pid: 123 } as ChildProcessWithoutNullStreams,
+      startedAt: Date.now(),
+      cwd: "/tmp",
+      maxOutputChars: 5_000,
+      pendingMaxOutputChars: 30_000,
+      totalOutputChars: 0,
+      pendingStdout: [],
+      pendingStderr: [],
+      pendingStdoutChars: 0,
+      pendingStderrChars: 0,
+      aggregated: "",
+      tail: "",
+      exited: false,
+      exitCode: undefined,
+      exitSignal: undefined,
+      truncated: false,
+      backgrounded: true,
+    };
+
+    addSession(session);
+    appendOutput(session, "stdout", "x".repeat(10_000));
+
+    const drained = drainSession(session);
+    expect(drained.stdout.length).toBe(5_000);
+    expect(session.truncated).toBe(true);
+  });
+
+  it("caps stdout and stderr independently", () => {
+    const session: ProcessSession = {
+      id: "sess",
+      command: "echo test",
+      child: { pid: 123 } as ChildProcessWithoutNullStreams,
+      startedAt: Date.now(),
+      cwd: "/tmp",
+      maxOutputChars: 100,
+      pendingMaxOutputChars: 10,
+      totalOutputChars: 0,
+      pendingStdout: [],
+      pendingStderr: [],
+      pendingStdoutChars: 0,
+      pendingStderrChars: 0,
+      aggregated: "",
+      tail: "",
+      exited: false,
+      exitCode: undefined,
+      exitSignal: undefined,
+      truncated: false,
+      backgrounded: true,
+    };
+
+    addSession(session);
+    appendOutput(session, "stdout", "a".repeat(6));
+    appendOutput(session, "stdout", "b".repeat(6));
+    appendOutput(session, "stderr", "c".repeat(12));
+
+    const drained = drainSession(session);
+    expect(drained.stdout).toBe("a".repeat(4) + "b".repeat(6));
+    expect(drained.stderr).toBe("c".repeat(10));
+    expect(session.truncated).toBe(true);
+  });
+
   it("only persists finished sessions when backgrounded", () => {
     const session: ProcessSession = {
       id: "sess",
@@ -51,9 +154,12 @@ describe("bash process registry", () => {
       startedAt: Date.now(),
       cwd: "/tmp",
       maxOutputChars: 100,
+      pendingMaxOutputChars: 30_000,
       totalOutputChars: 0,
       pendingStdout: [],
       pendingStderr: [],
+      pendingStdoutChars: 0,
+      pendingStderrChars: 0,
       aggregated: "",
       tail: "",
       exited: false,