From 29d17b9055e2993bb4b7e23bd8bf15d84f2d5792 Mon Sep 17 00:00:00 2001
From: Luke Parker <10430890+Hona@users.noreply.github.com>
Date: Fri, 29 May 2026 13:47:50 +1000
Subject: [PATCH] fix(opencode): allow pid 0 in Pty.Info for Windows ConPTY
 (#29828)

---
 packages/opencode/src/pty/index.ts            |  6 +++-
 .../opencode/test/pty/info-schema.test.ts     | 33 +++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 packages/opencode/test/pty/info-schema.test.ts

diff --git a/packages/opencode/src/pty/index.ts b/packages/opencode/src/pty/index.ts
index b5eab9ce36..9905aa4f64 100644
--- a/packages/opencode/src/pty/index.ts
+++ b/packages/opencode/src/pty/index.ts
@@ -60,7 +60,11 @@ export const Info = Schema.Struct({
   args: Schema.Array(Schema.String),
   cwd: Schema.String,
   status: Schema.Literals(["running", "exited"]),
-  pid: PositiveInt,
+  // Windows ConPTY (@lydell/node-pty >= 1.2.0-beta.12) assigns the child pid
+  // asynchronously, so `proc.pid` is 0 at the synchronous spawn point and only
+  // resolves a tick later. `create` snapshots it immediately, so 0 is a valid
+  // "pid not yet assigned" value here.
+  pid: NonNegativeInt,
 }).annotate({ identifier: "Pty" })
 
 export type Info = Types.DeepMutable<Schema.Schema.Type<typeof Info>>
diff --git a/packages/opencode/test/pty/info-schema.test.ts b/packages/opencode/test/pty/info-schema.test.ts
new file mode 100644
index 0000000000..429f29b00e
--- /dev/null
+++ b/packages/opencode/test/pty/info-schema.test.ts
@@ -0,0 +1,33 @@
+import { describe, expect, test } from "bun:test"
+import { Schema } from "effect"
+import { Pty } from "../../src/pty"
+
+// Windows ConPTY (via @lydell/node-pty >= 1.2.0-beta.12) assigns the child pid
+// asynchronously: `proc.pid` reads back as 0 at the synchronous spawn point and
+// only resolves to the real pid a tick later. `Pty.create` snapshots `proc.pid`
+// while building `Info`, so `Info.pid` legitimately carries 0 right after spawn.
+// `Pty.Info` must be able to represent that, otherwise every `pty.create` on
+// Windows fails to encode/decode and the terminal feature is unusable.
+const sample = (pid: number) => ({
+  id: "pty_01J5Y5H0AH4Q4NXJ6P4C3P5V2K",
+  title: "demo",
+  command: "cmd.exe",
+  args: [],
+  cwd: "C:\\",
+  status: "running",
+  pid,
+})
+
+describe("Pty.Info", () => {
+  test("accepts pid 0 (Windows ConPTY assigns the pid asynchronously)", () => {
+    expect(Schema.decodeUnknownSync(Pty.Info)(sample(0)).pid).toBe(0)
+  })
+
+  test("accepts a positive pid", () => {
+    expect(Schema.decodeUnknownSync(Pty.Info)(sample(48012)).pid).toBe(48012)
+  })
+
+  test("rejects a negative pid", () => {
+    expect(() => Schema.decodeUnknownSync(Pty.Info)(sample(-1))).toThrow()
+  })
+})