Port upstream PR #329: Hide CLI console window on Windows

[Copilot]

Upstream PR #329 adds windowsHide: true (Node.js), CREATE_NO_WINDOW (Python), and SysProcAttr.HideWindow (Go) to prevent a console window flash when spawning the CLI from GUI applications.

JVM already handles this — OpenJDK's ProcessImpl_md.c sets CREATE_NO_WINDOW automatically when all stdio handles are pipes (not inherited from parent console):

// ProcessImpl_md.c — processCreate()
DWORD processFlag = CREATE_NO_WINDOW | CREATE_UNICODE_ENVIRONMENT;
if (GetConsoleWindow() != NULL &&
    (si.hStdInput == stdIOE[0] || si.hStdOutput == stdIOE[1] || ...))
    processFlag &= ~CREATE_NO_WINDOW;  // only removed when handles are inherited

Since ProcessBuilder defaults to Redirect.PIPE for all streams, we get CREATE_NO_WINDOW for free. No JNA needed.

• process.clj: Add explicit Redirect.PIPE calls for all three streams — makes the Windows intent self-documenting and guards against regressions if someone later switches a redirect to INHERIT
• CHANGELOG.md: Upstream sync entry for PR #329

Original prompt

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This section details on the original issue you should resolve

<issue_title>Port upstream PR #329: Hide CLI console window on Windows</issue_title>
<issue_description>## Upstream Change

Upstream PR github/copilot-sdk#329 adds automatic hiding of the CLI console window on Windows when spawning the CLI subprocess. This prevents a distracting terminal window appearing in GUI applications.

Node.js change (nodejs/src/client.ts):

this.cliProcess = spawn(command, spawnArgs, {
    stdio: ...,
    cwd: this.options.cwd,
    env: envWithoutNodeDebug,
    windowsHide: true,  // <-- added
});

Why Not Auto-Ported

The Clojure SDK uses Java's ProcessBuilder to spawn the CLI process (src/github/copilot_sdk/process.clj). Unlike Node.js's spawn which has a built-in windowsHide option, ProcessBuilder does not support hiding the Windows console window natively.

Options to port this to JVM:

1. JNA (Java Native Access) — Add a JNA dependency and call Windows CreateProcess directly with CREATE_NO_WINDOW. This adds a native dependency but works cleanly.

2. Reflection into ProcessImpl — Fragile, not recommended.

3. Accept as JVM limitation — Document that on Windows, a console window may briefly appear. The SDK primarily targets server-side use cases where this is less of a concern.

4. ProcessBuilder.inheritIO() + redirects — Doesn't help with window visibility.

Recommendation

If the Clojure SDK targets Windows GUI applications, option 1 (JNA) is the cleanest approach. Otherwise, document the limitation.

The relevant Clojure file to modify is src/github/copilot_sdk/process.clj, specifically the spawn-cli function (lines 29-88).

Affected Upstream Files

• nodejs/src/client.ts — windowsHide: true in both stdio and TCP spawn calls
• python/copilot/client.py — CREATE_NO_WINDOW flag on Windows
• go/client.go + go/process_windows.go — platform-specific SysProcAttr.HideWindow

Testing

After implementing, verify that on Windows, no console window appears when using the SDK from a GUI application (e.g., a JavaFX or Swing app).

Generated by Upstream Sync Agent

Comments on the Issue (you are @copilot in this section)

• Fixes Port upstream PR #329: Hide CLI console window on Windows #27

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[Copilot]

Pull request overview

This PR ports upstream PR #329, which adds automatic hiding of the CLI console window on Windows when spawning the CLI subprocess from GUI applications. While the upstream Node.js SDK added an explicit windowsHide: true option, the JVM already provides this behavior through OpenJDK's ProcessImpl_md.c, which sets CREATE_NO_WINDOW when all stdio handles use PIPE redirects (not INHERIT).

Changes:

• Made PIPE redirects explicit in spawn-cli to ensure Windows console hiding and document the intent
• Added CHANGELOG entry documenting the upstream sync

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/github/copilot_sdk/process.clj	Added explicit PIPE redirects for stdin/stdout/stderr with detailed comments explaining the Windows CREATE_NO_WINDOW behavior
CHANGELOG.md	Added entry under "Added (upstream PR #329 sync)" documenting the Windows console window hiding feature

[krukow]

Reviewed PR #28. I don't see any blocking issues: explicit PIPE redirects in process.clj preserve current behavior while making the Windows no-console intent explicit, and the changelog entry accurately documents the upstream parity.