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fix(lume): preserve raw ssh command output #1701

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8 changes: 4 additions & 4 deletions libs/lume/src/Commands/SSH.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -101,8 +101,8 @@ struct SSH: AsyncParsableCommand {
timeout: TimeInterval(timeout)
)

if !result.output.isEmpty {
print(result.output)
if !result.outputData.isEmpty {
FileHandle.standardOutput.write(result.outputData)
}

if result.exitCode != 0 {
Expand All @@ -129,8 +129,8 @@ struct SSH: AsyncParsableCommand {
timeout: TimeInterval(timeout)
)

if !result.output.isEmpty {
print(result.output)
if !result.outputData.isEmpty {
FileHandle.standardOutput.write(result.outputData)
}

if result.exitCode != 0 {
Expand Down
16 changes: 12 additions & 4 deletions libs/lume/src/SSH/SSHClient.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -7,12 +7,20 @@ import Foundation
/// Result of an SSH command execution
public struct SSHResult: Sendable {
public let exitCode: Int32
public let outputData: Data
public let output: String

public init(exitCode: Int32, output: String) {
self.exitCode = exitCode
self.outputData = Data(output.utf8)
self.output = output
}

public init(exitCode: Int32, outputData: Data) {
self.exitCode = exitCode
self.outputData = outputData
self.output = String(decoding: outputData, as: UTF8.self)
}
}

/// SSH client using SwiftNIO SSH for typed, versioned API
Expand Down Expand Up @@ -310,13 +318,13 @@ private final class CommandExecHandler: ChannelDuplexHandler, @unchecked Sendabl
// Complete when we have exit status (some servers close channel before sending exit status)
if let status = exitStatus {
resultPromise = nil
let output = outputBuffer.readString(length: outputBuffer.readableBytes) ?? ""
promise.succeed(SSHResult(exitCode: status, output: output))
let outputData = outputBuffer.readData(length: outputBuffer.readableBytes) ?? Data()
promise.succeed(SSHResult(exitCode: status, outputData: outputData))
} else if channelClosed {
// Channel closed without exit status - assume success with exit code 0
resultPromise = nil
let output = outputBuffer.readString(length: outputBuffer.readableBytes) ?? ""
promise.succeed(SSHResult(exitCode: 0, output: output))
let outputData = outputBuffer.readData(length: outputBuffer.readableBytes) ?? Data()
promise.succeed(SSHResult(exitCode: 0, outputData: outputData))
}
}

Expand Down
8 changes: 5 additions & 3 deletions libs/lume/src/SSH/SystemSSHClient.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,6 @@ public final class SystemSSHClient: Sendable {

let stdoutData = stdoutPipe.fileHandleForReading.readDataToEndOfFile()
let stderrData = stderrPipe.fileHandleForReading.readDataToEndOfFile()
let output = String(data: stdoutData, encoding: .utf8) ?? ""
let errorOutput = String(data: stderrData, encoding: .utf8) ?? ""

// Filter out SSH warnings from stderr (known_hosts, etc.)
Expand All @@ -73,11 +72,14 @@ public final class SystemSSHClient: Sendable {
}
.joined(separator: "\n")

let combinedOutput = filteredError.isEmpty ? output : output + filteredError
var outputData = stdoutData
if !filteredError.isEmpty, let errorData = filteredError.data(using: .utf8) {
outputData.append(errorData)
}
Comment on lines +75 to +78
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@coderabbitai coderabbitai Bot May 26, 2026

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⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Do not append stderr bytes into outputData.

This reintroduces stream corruption for binary stdout whenever non-filtered stderr exists, because outputData is no longer raw stdout-only bytes.

Suggested change 
-        var outputData = stdoutData
-        if !filteredError.isEmpty, let errorData = filteredError.data(using: .utf8) {
-            outputData.append(errorData)
-        }
+        let outputData = stdoutData
📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
var outputData = stdoutData
if !filteredError.isEmpty, let errorData = filteredError.data(using: .utf8) {
outputData.append(errorData)
}
let outputData = stdoutData
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@libs/lume/src/SSH/SystemSSHClient.swift` around lines 75 - 78, The code
currently appends filtered stderr text bytes into outputData (the stdout buffer)
which corrupts binary stdout; revert this by removing the append of errorData
into outputData so outputData remains exactly stdoutData, and instead preserve
filteredError (or errorData) in its own variable/return value if callers need
stderr separately; update the logic around outputData, stdoutData, filteredError
in SystemSSHClient.swift (the outputData/filteredError handling) so stdout bytes
are never mutated with stderr bytes.


return SSHResult(
exitCode: process.terminationStatus,
output: combinedOutput
outputData: outputData
)
}

Expand Down
15 changes: 15 additions & 0 deletions libs/lume/tests/SSHResultTests.swift
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Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
import Foundation
import Testing

@testable import lume

@Test("SSHResult preserves raw output bytes alongside text view")
func testSSHResultPreservesRawOutputBytes() {
let bytes = Data([0x00, 0xff, 0x41, 0x80, 0x42])
let result = SSHResult(exitCode: 0, outputData: bytes)

#expect(result.outputData == bytes)
#expect(result.output.contains("A"))
#expect(result.output.contains("B"))
}