diff --git a/packages/opencode/src/tool/bash.ts b/packages/opencode/src/tool/bash.ts
index 671829c0f8..19e8330f62 100644
--- a/packages/opencode/src/tool/bash.ts
+++ b/packages/opencode/src/tool/bash.ts
@@ -177,16 +177,23 @@ export const BashTool = Tool.define("bash", async () => {
         { cwd, sessionID: ctx.sessionID, callID: ctx.callID },
         { env: {} },
       )
-      const proc = spawn(params.command, {
-        shell,
+      const env = {
+        ...process.env,
+        ...shellEnv.env,
+      }
+      const opts = {
         cwd,
-        env: {
-          ...process.env,
-          ...shellEnv.env,
-        },
-        stdio: ["ignore", "pipe", "pipe"],
+        env,
+        stdio: ["ignore", "pipe", "pipe"] as const,
         detached: process.platform !== "win32",
-      })
+      }
+      const proc =
+        process.platform === "win32" && ["pwsh", "powershell"].includes(name.toLowerCase())
+          ? spawn(shell, ["-NoLogo", "-NoProfile", "-NonInteractive", "-Command", params.command], opts)
+          : spawn(params.command, {
+              ...opts,
+              shell,
+            })
 
       let output = ""
 
@@ -243,6 +250,10 @@ export const BashTool = Tool.define("bash", async () => {
 
         proc.once("exit", () => {
           exited = true
+        })
+
+        proc.once("close", () => {
+          exited = true
           cleanup()
           resolve()
         })
diff --git a/packages/opencode/test/tool/bash.test.ts b/packages/opencode/test/tool/bash.test.ts
index ad4441af9b..62e7048d12 100644
--- a/packages/opencode/test/tool/bash.test.ts
+++ b/packages/opencode/test/tool/bash.test.ts
@@ -23,7 +23,14 @@ const ctx = {
 const projectRoot = path.join(__dirname, "../..")
 const bin = process.execPath.replaceAll("\\", "/")
 const file = path.join(projectRoot, "test/tool/fixtures/output.ts").replaceAll("\\", "/")
-const fill = (mode: "lines" | "bytes", n: number) => `${bin} ${file} ${mode} ${n}`
+const kind = () => path.win32.basename(process.env.SHELL || "", ".exe").toLowerCase()
+const fill = (mode: "lines" | "bytes", n: number) => {
+  if (["pwsh", "powershell"].includes(kind())) {
+    if (mode === "lines") return `1..${n} | ForEach-Object { $_ }`
+    return `Write-Output ('a' * ${n})`
+  }
+  return `${bin} ${file} ${mode} ${n}`
+}
 const shells = (() => {
   if (process.platform !== "win32") {
     const shell = process.env.SHELL || Bun.which("bash") || "/bin/sh"
@@ -322,10 +329,13 @@ describe("tool.bash permissions", () => {
             requests.push(req)
           },
         }
-        await bash.execute({ command: "cat > /tmp/output.txt", description: "Redirect ls output" }, testCtx)
+        const command = ["pwsh", "powershell"].includes(kind())
+          ? "Write-Output test > output.txt"
+          : "cat > /tmp/output.txt"
+        await bash.execute({ command, description: "Redirect ls output" }, testCtx)
         const bashReq = requests.find((r) => r.permission === "bash")
         expect(bashReq).toBeDefined()
-        expect(bashReq!.patterns).toContain("cat > /tmp/output.txt")
+        expect(bashReq!.patterns).toContain(command)
       },
     })
   })
@@ -431,7 +441,7 @@ describe("tool.bash truncation", () => {
         expect(filepath).toBeTruthy()
 
         const saved = await Filesystem.readText(filepath)
-        const lines = saved.trim().split("\n")
+        const lines = saved.trim().split(/\r?\n/)
         expect(lines.length).toBe(lineCount)
         expect(lines[0]).toBe("1")
         expect(lines[lineCount - 1]).toBe(String(lineCount))