diff --git a/src/agents/bash-process-registry.test.ts b/src/agents/bash-process-registry.test.ts
index 1c28facc4..2c5b04561 100644
--- a/src/agents/bash-process-registry.test.ts
+++ b/src/agents/bash-process-registry.test.ts
@@ -1,4 +1,6 @@
+import type { ChildProcessWithoutNullStreams } from "node:child_process";
 import { beforeEach, describe, expect, it } from "vitest";
+import type { ProcessSession } from "./bash-process-registry.js";
 import {
   addSession,
   appendOutput,
@@ -8,20 +10,16 @@ import {
   resetProcessRegistryForTests,
 } from "./bash-process-registry.js";
 
-type DummyChild = {
-  pid?: number;
-};
-
 describe("bash process registry", () => {
   beforeEach(() => {
     resetProcessRegistryForTests();
   });
 
   it("captures output and truncates", () => {
-    const session = {
+    const session: ProcessSession = {
       id: "sess",
       command: "echo test",
-      child: { pid: 123 } as DummyChild,
+      child: { pid: 123 } as ChildProcessWithoutNullStreams,
       startedAt: Date.now(),
       cwd: "/tmp",
       maxOutputChars: 10,
@@ -37,19 +35,19 @@ describe("bash process registry", () => {
       backgrounded: false,
     };
 
-    addSession(session as any);
-    appendOutput(session as any, "stdout", "0123456789");
-    appendOutput(session as any, "stdout", "abcdef");
+    addSession(session);
+    appendOutput(session, "stdout", "0123456789");
+    appendOutput(session, "stdout", "abcdef");
 
     expect(session.aggregated).toBe("6789abcdef");
     expect(session.truncated).toBe(true);
   });
 
   it("only persists finished sessions when backgrounded", () => {
-    const session = {
+    const session: ProcessSession = {
       id: "sess",
       command: "echo test",
-      child: { pid: 123 } as DummyChild,
+      child: { pid: 123 } as ChildProcessWithoutNullStreams,
       startedAt: Date.now(),
       cwd: "/tmp",
       maxOutputChars: 100,
@@ -65,12 +63,12 @@ describe("bash process registry", () => {
       backgrounded: false,
     };
 
-    addSession(session as any);
-    markExited(session as any, 0, null, "completed");
+    addSession(session);
+    markExited(session, 0, null, "completed");
     expect(listFinishedSessions()).toHaveLength(0);
 
-    markBackgrounded(session as any);
-    markExited(session as any, 0, null, "completed");
+    markBackgrounded(session);
+    markExited(session, 0, null, "completed");
     expect(listFinishedSessions()).toHaveLength(1);
   });
 });
diff --git a/src/agents/bash-process-registry.ts b/src/agents/bash-process-registry.ts
index 35ac3dd90..44bf39dcf 100644
--- a/src/agents/bash-process-registry.ts
+++ b/src/agents/bash-process-registry.ts
@@ -79,12 +79,17 @@ export function appendOutput(
 ) {
   session.pendingStdout ??= [];
   session.pendingStderr ??= [];
-  const buffer = stream === "stdout" ? session.pendingStdout : session.pendingStderr;
+  const buffer =
+    stream === "stdout" ? session.pendingStdout : session.pendingStderr;
   buffer.push(chunk);
   session.totalOutputChars += chunk.length;
-  const aggregated = trimWithCap(session.aggregated + chunk, session.maxOutputChars);
+  const aggregated = trimWithCap(
+    session.aggregated + chunk,
+    session.maxOutputChars,
+  );
   session.truncated =
-    session.truncated || aggregated.length < session.aggregated.length + chunk.length;
+    session.truncated ||
+    aggregated.length < session.aggregated.length + chunk.length;
   session.aggregated = aggregated;
   session.tail = tail(session.aggregated, 2000);
 }
@@ -175,6 +180,9 @@ function pruneFinishedSessions() {
 
 function startSweeper() {
   if (sweeper) return;
-  sweeper = setInterval(pruneFinishedSessions, Math.max(30_000, JOB_TTL_MS / 6));
+  sweeper = setInterval(
+    pruneFinishedSessions,
+    Math.max(30_000, JOB_TTL_MS / 6),
+  );
   sweeper.unref?.();
 }
diff --git a/src/agents/bash-tools.test.ts b/src/agents/bash-tools.test.ts
index 775d0ecf9..ef4f61bbe 100644
--- a/src/agents/bash-tools.test.ts
+++ b/src/agents/bash-tools.test.ts
@@ -1,6 +1,6 @@
 import { beforeEach, describe, expect, it } from "vitest";
-import { bashTool, processTool } from "./bash-tools.js";
 import { resetProcessRegistryForTests } from "./bash-process-registry.js";
+import { bashTool, processTool } from "./bash-tools.js";
 
 const sleep = (ms: number) => new Promise((resolve) => setTimeout(resolve, ms));
 
@@ -49,7 +49,9 @@ describe("bash tool backgrounding", () => {
     const sessionId = (result.details as { sessionId: string }).sessionId;
 
     const list = await processTool.execute("call2", { action: "list" });
-    const sessions = (list.details as { sessions: Array<{ sessionId: string }> }).sessions;
+    const sessions = (
+      list.details as { sessions: Array<{ sessionId: string }> }
+    ).sessions;
     expect(sessions.some((s) => s.sessionId === sessionId)).toBe(true);
   });
 });
diff --git a/src/agents/bash-tools.ts b/src/agents/bash-tools.ts
index 2679e678a..fa8dd7688 100644
--- a/src/agents/bash-tools.ts
+++ b/src/agents/bash-tools.ts
@@ -1,8 +1,8 @@
+import { type ChildProcessWithoutNullStreams, spawn } from "node:child_process";
+import { randomUUID } from "node:crypto";
 import type { AgentTool, AgentToolResult } from "@mariozechner/pi-ai";
 import { StringEnum } from "@mariozechner/pi-ai";
 import { Type } from "@sinclair/typebox";
-import { type ChildProcessWithoutNullStreams, spawn } from "node:child_process";
-import { randomUUID } from "node:crypto";
 
 import {
   addSession,
@@ -16,7 +16,11 @@ import {
   markBackgrounded,
   markExited,
 } from "./bash-process-registry.js";
-import { getShellConfig, killProcessTree, sanitizeBinaryOutput } from "./shell-utils.js";
+import {
+  getShellConfig,
+  killProcessTree,
+  sanitizeBinaryOutput,
+} from "./shell-utils.js";
 
 const CHUNK_LIMIT = 8 * 1024;
 const DEFAULT_YIELD_MS = clampNumber(
@@ -79,7 +83,7 @@ export const bashTool: AgentTool<typeof bashSchema, BashToolDetails> = {
   description:
     "Execute bash with background continuation. Use yieldMs/background to continue later via process tool.",
   parameters: bashSchema,
-  execute: async (toolCallId, args, signal, onUpdate) => {
+  execute: async (_toolCallId, args, signal, onUpdate) => {
     const params = args as {
       command: string;
       workdir?: string;
@@ -106,12 +110,13 @@ export const bashTool: AgentTool<typeof bashSchema, BashToolDetails> = {
     const workdir = params.workdir?.trim() || process.cwd();
 
     const { shell, args: shellArgs } = getShellConfig();
+    const env = params.env ?? {};
     const child: ChildProcessWithoutNullStreams = spawn(
       shell,
       [...shellArgs, params.command],
       {
         cwd: workdir,
-        env: { ...process.env, ...(params.env ?? {}) },
+        env: { ...process.env, ...env },
         detached: true,
         stdio: ["pipe", "pipe", "pipe"],
       },
@@ -243,8 +248,11 @@ export const bashTool: AgentTool<typeof bashSchema, BashToolDetails> = {
         if (timeoutTimer) clearTimeout(timeoutTimer);
         const durationMs = Date.now() - startedAt;
         const wasSignal = exitSignal != null;
-        const isSuccess = code === 0 && !wasSignal && !signal?.aborted && !timedOut;
-        const status: "completed" | "failed" = isSuccess ? "completed" : "failed";
+        const isSuccess =
+          code === 0 && !wasSignal && !signal?.aborted && !timedOut;
+        const status: "completed" | "failed" = isSuccess
+          ? "completed"
+          : "failed";
         markExited(session, code, exitSignal, status);
 
         if (yielded || session.backgrounded) return;
@@ -352,7 +360,10 @@ export const processTool: AgentTool<typeof processSchema> = {
         );
       return {
         content: [
-          { type: "text", text: lines.join("\n") || "No running or recent sessions." },
+          {
+            type: "text",
+            text: lines.join("\n") || "No running or recent sessions.",
+          },
         ],
         details: { status: "completed", sessions: [...running, ...finished] },
       };
@@ -360,7 +371,9 @@ export const processTool: AgentTool<typeof processSchema> = {
 
     if (!params.sessionId) {
       return {
-        content: [{ type: "text", text: "sessionId is required for this action." }],
+        content: [
+          { type: "text", text: "sessionId is required for this action." },
+        ],
         details: { status: "failed" },
       };
     }
@@ -389,7 +402,8 @@ export const processTool: AgentTool<typeof processSchema> = {
                 },
               ],
               details: {
-                status: finished.status === "completed" ? "completed" : "failed",
+                status:
+                  finished.status === "completed" ? "completed" : "failed",
                 sessionId: params.sessionId,
                 exitCode: finished.exitCode ?? undefined,
                 aggregated: finished.aggregated,
@@ -398,7 +412,10 @@ export const processTool: AgentTool<typeof processSchema> = {
           }
           return {
             content: [
-              { type: "text", text: `No session found for ${params.sessionId}` },
+              {
+                type: "text",
+                text: `No session found for ${params.sessionId}`,
+              },
             ],
             details: { status: "failed" },
           };
@@ -421,7 +438,12 @@ export const processTool: AgentTool<typeof processSchema> = {
         if (exited) {
           const status =
             exitCode === 0 && exitSignal == null ? "completed" : "failed";
-          markExited(session, session.exitCode ?? null, session.exitSignal ?? null, status);
+          markExited(
+            session,
+            session.exitCode ?? null,
+            session.exitSignal ?? null,
+            status,
+          );
         }
         const status = exited
           ? exitCode === 0 && exitSignal == null
@@ -470,9 +492,7 @@ export const processTool: AgentTool<typeof processSchema> = {
           const total = session.aggregated.length;
           const slice = session.aggregated.slice(
             params.offset ?? 0,
-            params.limit
-              ? (params.offset ?? 0) + params.limit
-              : undefined,
+            params.limit ? (params.offset ?? 0) + params.limit : undefined,
           );
           return {
             content: [{ type: "text", text: slice || "(no output yet)" }],
@@ -488,15 +508,12 @@ export const processTool: AgentTool<typeof processSchema> = {
           const total = finished.aggregated.length;
           const slice = finished.aggregated.slice(
             params.offset ?? 0,
-            params.limit
-              ? (params.offset ?? 0) + params.limit
-              : undefined,
+            params.limit ? (params.offset ?? 0) + params.limit : undefined,
           );
-          const status = finished.status === "completed" ? "completed" : "failed";
+          const status =
+            finished.status === "completed" ? "completed" : "failed";
           return {
-            content: [
-              { type: "text", text: slice || "(no output recorded)" },
-            ],
+            content: [{ type: "text", text: slice || "(no output recorded)" }],
             details: {
               status,
               sessionId: params.sessionId,
@@ -519,7 +536,10 @@ export const processTool: AgentTool<typeof processSchema> = {
         if (!session) {
           return {
             content: [
-              { type: "text", text: `No active session found for ${params.sessionId}` },
+              {
+                type: "text",
+                text: `No active session found for ${params.sessionId}`,
+              },
             ],
             details: { status: "failed" },
           };
@@ -572,7 +592,10 @@ export const processTool: AgentTool<typeof processSchema> = {
         if (!session) {
           return {
             content: [
-              { type: "text", text: `No active session found for ${params.sessionId}` },
+              {
+                type: "text",
+                text: `No active session found for ${params.sessionId}`,
+              },
             ],
             details: { status: "failed" },
           };
diff --git a/src/agents/shell-utils.ts b/src/agents/shell-utils.ts
index 488c65a53..6302b51d3 100644
--- a/src/agents/shell-utils.ts
+++ b/src/agents/shell-utils.ts
@@ -11,9 +11,20 @@ export function getShellConfig(): { shell: string; args: string[] } {
 }
 
 export function sanitizeBinaryOutput(text: string): string {
-  return text
-    .replace(/[\p{Format}\p{Surrogate}]/gu, "")
-    .replace(/[\x00-\x08\x0B\x0C\x0E-\x1F]/g, "");
+  const scrubbed = text.replace(/[\p{Format}\p{Surrogate}]/gu, "");
+  if (!scrubbed) return scrubbed;
+  const chunks: string[] = [];
+  for (const char of scrubbed) {
+    const code = char.codePointAt(0);
+    if (code == null) continue;
+    if (code === 0x09 || code === 0x0a || code === 0x0d) {
+      chunks.push(char);
+      continue;
+    }
+    if (code < 0x20) continue;
+    chunks.push(char);
+  }
+  return chunks.join("");
 }
 
 export function killProcessTree(pid: number): void {