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Fix Windows wizard failure by sending prompt via stdin for stream-json mode #302

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pedramamini merged 1 commit into from
Feb 5, 2026
Merged

Fix Windows wizard failure by sending prompt via stdin for stream-json mode #302

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6 changes: 5 additions & 1 deletion src/main/process-manager/spawners/ChildProcessSpawner.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -73,7 +73,11 @@ export class ChildProcessSpawner {

// Check if prompt will be sent via stdin instead of command line
// This is critical for SSH remote execution to avoid shell escaping issues
const promptViaStdin = sendPromptViaStdin || sendPromptViaStdinRaw;
// Also critical on Windows: when using stream-json output mode, the prompt is sent
// via stdin (see stream-json stdin write below). Adding it as a CLI arg too would
// exceed cmd.exe's ~8191 character command line limit, causing immediate exit code 1.
const argsHaveStreamJson = args.some((arg) => arg.includes('stream-json'));
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Copilot AI Feb 5, 2026

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The detection logic using .includes('stream-json') could potentially match unintended patterns. For example, if a hypothetical flag like --no-stream-json or --stream-json-disabled were used, it would incorrectly trigger stdin mode. Consider using a more precise check that matches the specific expected patterns like arg === 'stream-json' after splitting on equals signs, or check for --output-format followed by stream-json, or --input-format followed by stream-json.

Suggested change
const argsHaveStreamJson = args.some((arg) => arg.includes('stream-json'));
const argsHaveStreamJson = args.some((arg, index) => {
// Match common patterns:
// - bare "stream-json"
// - "--input-format stream-json" / "--output-format stream-json"
// - "--input-format=stream-json" / "--output-format=stream-json"
if (arg === 'stream-json') {
return true;
}
if (arg === '--input-format' || arg === '--output-format') {
return args[index + 1] === 'stream-json';
}
if (arg.startsWith('--input-format=') || arg.startsWith('--output-format=')) {
const [, value] = arg.split('=', 2);
return value === 'stream-json';
}
return false;
});

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const promptViaStdin = sendPromptViaStdin || sendPromptViaStdinRaw || argsHaveStreamJson;
Comment on lines +79 to +80
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Copilot AI Feb 5, 2026

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There is no test coverage for the new behavior where promptViaStdin is set to true when args contain 'stream-json'. While there are tests that verify isStreamJsonMode detection (lines 132-243 in ChildProcessSpawner.test.ts), there should be a test that verifies the prompt is NOT added to the command line arguments when args contain 'stream-json'. This would ensure the Windows command line length fix is properly covered by tests.

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// Build final args based on batch mode and images
let finalArgs: string[];
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