Refactor runner and installation scripts for improved functionality

- Removed the `--disable-hiprt` flag from the runner command, simplifying the rendering options for users.
- Updated the `jiggablend-runner` script and README to reflect the removal of the HIPRT control flag, enhancing clarity in usage instructions.
- Enhanced the installation script to provide clearer examples for running the jiggablend manager and runner, improving user experience during setup.
- Implemented a more robust GPU backend detection mechanism, allowing for better compatibility with various hardware configurations.

internal/runner/api/manager.go

@@ -241,8 +241,8 @@ func (m *ManagerClient) DownloadContext(contextPath, jobToken string) (io.ReadCl
 	}
 
 	if resp.StatusCode != http.StatusOK {
+		defer resp.Body.Close()
 		body, _ := io.ReadAll(resp.Body)
-		resp.Body.Close()
 		return nil, fmt.Errorf("context download failed with status %d: %s", resp.StatusCode, string(body))
 	}
 
@@ -435,8 +435,8 @@ func (m *ManagerClient) DownloadBlender(version string) (io.ReadCloser, error) {
 	}
 
 	if resp.StatusCode != http.StatusOK {
+		defer resp.Body.Close()
 		body, _ := io.ReadAll(resp.Body)
-		resp.Body.Close()
 		return nil, fmt.Errorf("failed to download blender: status %d, body: %s", resp.StatusCode, string(body))
 	}
 

internal/runner/blender/detect.go

@@ -1,45 +1,116 @@
-// Package blender: GPU backend detection for HIP vs NVIDIA.
+// Package blender: host GPU backend detection for AMD/NVIDIA/Intel.
 package blender
 
 import (
 	"bufio"
-	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strconv"
 	"strings"
-
-	"jiggablend/pkg/scripts"
 )
 
-// DetectGPUBackends runs a minimal Blender script to detect whether HIP (AMD) and/or
-// NVIDIA (CUDA/OptiX) devices are available. Use this to decide whether to force CPU
-// for Blender < 4.x (only force when HIP is present, since HIP has no official support pre-4).
-func DetectGPUBackends(blenderBinary, scriptDir string) (hasHIP, hasNVIDIA bool, err error) {
-	scriptPath := filepath.Join(scriptDir, "detect_gpu_backends.py")
-	if err := os.WriteFile(scriptPath, []byte(scripts.DetectGPUBackends), 0644); err != nil {
-		return false, false, fmt.Errorf("write detection script: %w", err)
-	}
-	defer os.Remove(scriptPath)
+// DetectGPUBackends detects whether AMD, NVIDIA, and/or Intel GPUs are available
+// using host-level hardware probing only.
+func DetectGPUBackends() (hasAMD, hasNVIDIA, hasIntel bool, ok bool) {
+	return detectGPUBackendsFromHost()
+}
 
-	env := TarballEnv(blenderBinary, os.Environ())
-	cmd := exec.Command(blenderBinary, "-b", "--python", scriptPath)
-	cmd.Env = env
-	cmd.Dir = scriptDir
-	out, err := cmd.CombinedOutput()
+func detectGPUBackendsFromHost() (hasAMD, hasNVIDIA, hasIntel bool, ok bool) {
+	if amd, nvidia, intel, found := detectGPUBackendsFromDRM(); found {
+		return amd, nvidia, intel, true
+	}
+	if amd, nvidia, intel, found := detectGPUBackendsFromLSPCI(); found {
+		return amd, nvidia, intel, true
+	}
+	return false, false, false, false
+}
+
+func detectGPUBackendsFromDRM() (hasAMD, hasNVIDIA, hasIntel bool, ok bool) {
+	entries, err := os.ReadDir("/sys/class/drm")
 	if err != nil {
-		return false, false, fmt.Errorf("run blender detection: %w (output: %s)", err, string(out))
+		return false, false, false, false
+	}
+
+	for _, entry := range entries {
+		name := entry.Name()
+		if !isDRMCardNode(name) {
+			continue
+		}
+
+		vendorPath := filepath.Join("/sys/class/drm", name, "device", "vendor")
+		vendorRaw, err := os.ReadFile(vendorPath)
+		if err != nil {
+			continue
+		}
+		vendor := strings.TrimSpace(strings.ToLower(string(vendorRaw)))
+		switch vendor {
+		case "0x1002":
+			hasAMD = true
+			ok = true
+		case "0x10de":
+			hasNVIDIA = true
+			ok = true
+		case "0x8086":
+			hasIntel = true
+			ok = true
+		}
+	}
+
+	return hasAMD, hasNVIDIA, hasIntel, ok
+}
+
+func isDRMCardNode(name string) bool {
+	if !strings.HasPrefix(name, "card") {
+		return false
+	}
+	if strings.Contains(name, "-") {
+		// Connector entries like card0-DP-1 are not GPU device nodes.
+		return false
+	}
+	if len(name) <= len("card") {
+		return false
+	}
+	_, err := strconv.Atoi(strings.TrimPrefix(name, "card"))
+	return err == nil
+}
+
+func detectGPUBackendsFromLSPCI() (hasAMD, hasNVIDIA, hasIntel bool, ok bool) {
+	if _, err := exec.LookPath("lspci"); err != nil {
+		return false, false, false, false
+	}
+
+	out, err := exec.Command("lspci").CombinedOutput()
+	if err != nil {
+		return false, false, false, false
 	}
 
 	scanner := bufio.NewScanner(strings.NewReader(string(out)))
 	for scanner.Scan() {
-		line := strings.TrimSpace(scanner.Text())
-		switch line {
-		case "HAS_HIP":
-			hasHIP = true
-		case "HAS_NVIDIA":
+		line := strings.ToLower(strings.TrimSpace(scanner.Text()))
+		if !isGPUControllerLine(line) {
+			continue
+		}
+
+		if strings.Contains(line, "nvidia") {
 			hasNVIDIA = true
+			ok = true
+		}
+		if strings.Contains(line, "amd") || strings.Contains(line, "ati") || strings.Contains(line, "radeon") {
+			hasAMD = true
+			ok = true
+		}
+		if strings.Contains(line, "intel") {
+			hasIntel = true
+			ok = true
 		}
 	}
-	return hasHIP, hasNVIDIA, scanner.Err()
+
+	return hasAMD, hasNVIDIA, hasIntel, ok
+}
+
+func isGPUControllerLine(line string) bool {
+	return strings.Contains(line, "vga compatible controller") ||
+		strings.Contains(line, "3d controller") ||
+		strings.Contains(line, "display controller")
 }

internal/runner/blender/version.go

@@ -1,143 +1,19 @@
 package blender
 
 import (
-	"compress/gzip"
 	"fmt"
-	"io"
-	"os"
-	"os/exec"
+
+	"jiggablend/pkg/blendfile"
 )
 
 // ParseVersionFromFile parses the Blender version that a .blend file was saved with.
 // Returns major and minor version numbers.
+// Delegates to the shared pkg/blendfile implementation.
 func ParseVersionFromFile(blendPath string) (major, minor int, err error) {
-	file, err := os.Open(blendPath)
-	if err != nil {
-		return 0, 0, fmt.Errorf("failed to open blend file: %w", err)
-	}
-	defer file.Close()
-
-	// Read the first 12 bytes of the blend file header
-	// Format: BLENDER-v<major><minor><patch> or BLENDER_v<major><minor><patch>
-	// The header is: "BLENDER" (7 bytes) + pointer size (1 byte: '-' for 64-bit, '_' for 32-bit)
-	// + endianness (1 byte: 'v' for little-endian, 'V' for big-endian)
-	// + version (3 bytes: e.g., "402" for 4.02)
-	header := make([]byte, 12)
-	n, err := file.Read(header)
-	if err != nil || n < 12 {
-		return 0, 0, fmt.Errorf("failed to read blend file header: %w", err)
-	}
-
-	// Check for BLENDER magic
-	if string(header[:7]) != "BLENDER" {
-		// Might be compressed - try to decompress
-		file.Seek(0, 0)
-		return parseCompressedVersion(file)
-	}
-
-	// Parse version from bytes 9-11 (3 digits)
-	versionStr := string(header[9:12])
-
-	// Version format changed in Blender 3.0
-	// Pre-3.0: "279" = 2.79, "280" = 2.80
-	// 3.0+: "300" = 3.0, "402" = 4.02, "410" = 4.10
-	if len(versionStr) == 3 {
-		// First digit is major version
-		fmt.Sscanf(string(versionStr[0]), "%d", &major)
-		// Next two digits are minor version
-		fmt.Sscanf(versionStr[1:3], "%d", &minor)
-	}
-
-	return major, minor, nil
-}
-
-// parseCompressedVersion handles gzip and zstd compressed blend files.
-func parseCompressedVersion(file *os.File) (major, minor int, err error) {
-	magic := make([]byte, 4)
-	if _, err := file.Read(magic); err != nil {
-		return 0, 0, err
-	}
-	file.Seek(0, 0)
-
-	if magic[0] == 0x1f && magic[1] == 0x8b {
-		// gzip compressed
-		gzReader, err := gzip.NewReader(file)
-		if err != nil {
-			return 0, 0, fmt.Errorf("failed to create gzip reader: %w", err)
-		}
-		defer gzReader.Close()
-
-		header := make([]byte, 12)
-		n, err := gzReader.Read(header)
-		if err != nil || n < 12 {
-			return 0, 0, fmt.Errorf("failed to read compressed blend header: %w", err)
-		}
-
-		if string(header[:7]) != "BLENDER" {
-			return 0, 0, fmt.Errorf("invalid blend file format")
-		}
-
-		versionStr := string(header[9:12])
-		if len(versionStr) == 3 {
-			fmt.Sscanf(string(versionStr[0]), "%d", &major)
-			fmt.Sscanf(versionStr[1:3], "%d", &minor)
-		}
-
-		return major, minor, nil
-	}
-
-	// Check for zstd magic (Blender 3.0+): 0x28 0xB5 0x2F 0xFD
-	if magic[0] == 0x28 && magic[1] == 0xb5 && magic[2] == 0x2f && magic[3] == 0xfd {
-		return parseZstdVersion(file)
-	}
-
-	return 0, 0, fmt.Errorf("unknown blend file format")
-}
-
-// parseZstdVersion handles zstd-compressed blend files (Blender 3.0+).
-// Uses zstd command line tool since Go doesn't have native zstd support.
-func parseZstdVersion(file *os.File) (major, minor int, err error) {
-	file.Seek(0, 0)
-
-	cmd := exec.Command("zstd", "-d", "-c")
-	cmd.Stdin = file
-
-	stdout, err := cmd.StdoutPipe()
-	if err != nil {
-		return 0, 0, fmt.Errorf("failed to create zstd stdout pipe: %w", err)
-	}
-
-	if err := cmd.Start(); err != nil {
-		return 0, 0, fmt.Errorf("failed to start zstd decompression: %w", err)
-	}
-
-	// Read just the header (12 bytes)
-	header := make([]byte, 12)
-	n, readErr := io.ReadFull(stdout, header)
-
-	// Kill the process early - we only need the header
-	cmd.Process.Kill()
-	cmd.Wait()
-
-	if readErr != nil || n < 12 {
-		return 0, 0, fmt.Errorf("failed to read zstd compressed blend header: %v", readErr)
-	}
-
-	if string(header[:7]) != "BLENDER" {
-		return 0, 0, fmt.Errorf("invalid blend file format in zstd archive")
-	}
-
-	versionStr := string(header[9:12])
-	if len(versionStr) == 3 {
-		fmt.Sscanf(string(versionStr[0]), "%d", &major)
-		fmt.Sscanf(versionStr[1:3], "%d", &minor)
-	}
-
-	return major, minor, nil
+	return blendfile.ParseVersionFromFile(blendPath)
 }
 
 // VersionString returns a formatted version string like "4.2".
 func VersionString(major, minor int) string {
 	return fmt.Sprintf("%d.%d", major, minor)
 }
-

internal/runner/runner.go

@@ -46,23 +46,22 @@ type Runner struct {
 	gpuLockedOut   bool
 	gpuLockedOutMu sync.RWMutex
 
-	// hasHIP/hasNVIDIA are set at startup by running latest Blender to detect GPU backends.
-	// Used to force CPU only for Blender < 4.x when HIP is present (no official HIP support pre-4).
-	// gpuDetectionFailed is true when detection could not run; we then force CPU for all versions (we could not determine HIP vs NVIDIA).
+	// hasAMD/hasNVIDIA/hasIntel are set at startup by hardware/Blender GPU backend detection.
+	// Used to force CPU only for Blender < 4.x when AMD is present (no official HIP support pre-4).
+	// gpuDetectionFailed is true when detection could not run; we then force CPU for all versions.
 	gpuBackendMu       sync.RWMutex
-	hasHIP             bool
+	hasAMD             bool
 	hasNVIDIA          bool
+	hasIntel           bool
 	gpuBackendProbed   bool
 	gpuDetectionFailed bool
 
 	// forceCPURendering forces CPU rendering for all jobs regardless of metadata/backend detection.
 	forceCPURendering bool
-	// disableHIPRT disables HIPRT acceleration when configuring Cycles HIP devices.
-	disableHIPRT bool
 }
 
 // New creates a new runner.
-func New(managerURL, name, hostname string, forceCPURendering, disableHIPRT bool) *Runner {
+func New(managerURL, name, hostname string, forceCPURendering bool) *Runner {
 	manager := api.NewManagerClient(managerURL)
 
 	r := &Runner{
@@ -74,7 +73,6 @@ func New(managerURL, name, hostname string, forceCPURendering, disableHIPRT bool
 		processors: make(map[string]tasks.Processor),
 
 		forceCPURendering: forceCPURendering,
-		disableHIPRT:      disableHIPRT,
 	}
 
 	// Generate fingerprint
@@ -93,25 +91,25 @@ func (r *Runner) CheckRequiredTools() error {
 	return nil
 }
 
-var cachedCapabilities map[string]interface{} = nil
+var (
+	cachedCapabilities map[string]interface{}
+	capabilitiesOnce   sync.Once
+)
 
 // ProbeCapabilities detects hardware capabilities.
 func (r *Runner) ProbeCapabilities() map[string]interface{} {
-	if cachedCapabilities != nil {
-		return cachedCapabilities
-	}
+	capabilitiesOnce.Do(func() {
+		caps := make(map[string]interface{})
 
-	caps := make(map[string]interface{})
+		if err := exec.Command("ffmpeg", "-version").Run(); err == nil {
+			caps["ffmpeg"] = true
+		} else {
+			caps["ffmpeg"] = false
+		}
 
-	// Check for ffmpeg and probe encoding capabilities
-	if err := exec.Command("ffmpeg", "-version").Run(); err == nil {
-		caps["ffmpeg"] = true
-	} else {
-		caps["ffmpeg"] = false
-	}
-
-	cachedCapabilities = caps
-	return caps
+		cachedCapabilities = caps
+	})
+	return cachedCapabilities
 }
 
 // Register registers the runner with the manager.
@@ -141,52 +139,66 @@ func (r *Runner) Register(apiKey string) (int64, error) {
 	return id, nil
 }
 
-// DetectAndStoreGPUBackends downloads the latest Blender from the manager (if needed),
-// runs a detection script to see if HIP (AMD) and/or NVIDIA devices are available,
-// and stores the result. Call after Register. Used so we only force CPU for Blender < 4.x
-// when the runner has HIP (no official HIP support pre-4); NVIDIA is allowed.
+// DetectAndStoreGPUBackends runs host-level backend detection and stores AMD/NVIDIA/Intel results.
+// Call after Register. Used so we only force CPU for Blender < 4.x when AMD is present.
 func (r *Runner) DetectAndStoreGPUBackends() {
 	r.gpuBackendMu.Lock()
 	defer r.gpuBackendMu.Unlock()
 	if r.gpuBackendProbed {
 		return
 	}
-	latestVer, err := r.manager.GetLatestBlenderVersion()
-	if err != nil {
-		log.Printf("GPU backend detection failed (could not get latest Blender version: %v). All jobs will use CPU because we could not determine HIP vs NVIDIA.", err)
+	hasAMD, hasNVIDIA, hasIntel, ok := blender.DetectGPUBackends()
+	if !ok {
+		log.Printf("GPU backend detection failed (host probe unavailable). All jobs will use CPU because backend availability is unknown.")
 		r.gpuBackendProbed = true
 		r.gpuDetectionFailed = true
 		return
 	}
-	binaryPath, err := r.blender.GetBinaryPath(latestVer)
-	if err != nil {
-		log.Printf("GPU backend detection failed (could not get Blender binary: %v). All jobs will use CPU because we could not determine HIP vs NVIDIA.", err)
-		r.gpuBackendProbed = true
-		r.gpuDetectionFailed = true
-		return
+
+	detectedTypes := 0
+	if hasAMD {
+		detectedTypes++
 	}
-	hasHIP, hasNVIDIA, err := blender.DetectGPUBackends(binaryPath, r.workspace.BaseDir())
-	if err != nil {
-		log.Printf("GPU backend detection failed (script error: %v). All jobs will use CPU because we could not determine HIP vs NVIDIA.", err)
-		r.gpuBackendProbed = true
-		r.gpuDetectionFailed = true
-		return
+	if hasNVIDIA {
+		detectedTypes++
 	}
-	r.hasHIP = hasHIP
+	if hasIntel {
+		detectedTypes++
+	}
+	if detectedTypes > 1 {
+		log.Printf("mixed GPU vendors detected (AMD=%v NVIDIA=%v INTEL=%v): multi-vendor setups may not work reliably, but runner will continue with GPU enabled", hasAMD, hasNVIDIA, hasIntel)
+	}
+
+	r.hasAMD = hasAMD
 	r.hasNVIDIA = hasNVIDIA
+	r.hasIntel = hasIntel
 	r.gpuBackendProbed = true
 	r.gpuDetectionFailed = false
-	log.Printf("GPU backend detection: HIP=%v NVIDIA=%v (Blender < 4.x will force CPU only when HIP is present)", hasHIP, hasNVIDIA)
+	log.Printf("GPU backend detection: AMD=%v NVIDIA=%v INTEL=%v (Blender < 4.x will force CPU only when AMD is present)", hasAMD, hasNVIDIA, hasIntel)
 }
 
-// HasHIP returns whether the runner detected HIP (AMD) devices. Used to force CPU for Blender < 4.x only when HIP is present.
-func (r *Runner) HasHIP() bool {
+// HasAMD returns whether the runner detected AMD devices. Used to force CPU for Blender < 4.x only when AMD is present.
+func (r *Runner) HasAMD() bool {
 	r.gpuBackendMu.RLock()
 	defer r.gpuBackendMu.RUnlock()
-	return r.hasHIP
+	return r.hasAMD
 }
 
-// GPUDetectionFailed returns true when startup GPU backend detection could not run or failed. When true, all jobs use CPU because we could not determine HIP vs NVIDIA.
+// HasNVIDIA returns whether the runner detected NVIDIA GPUs.
+func (r *Runner) HasNVIDIA() bool {
+	r.gpuBackendMu.RLock()
+	defer r.gpuBackendMu.RUnlock()
+	return r.hasNVIDIA
+}
+
+// HasIntel returns whether the runner detected Intel GPUs (e.g. Arc).
+func (r *Runner) HasIntel() bool {
+	r.gpuBackendMu.RLock()
+	defer r.gpuBackendMu.RUnlock()
+	return r.hasIntel
+}
+
+// GPUDetectionFailed returns true when startup GPU backend detection could not run or failed. When true, all jobs use CPU because backend availability is unknown.
 func (r *Runner) GPUDetectionFailed() bool {
 	r.gpuBackendMu.RLock()
 	defer r.gpuBackendMu.RUnlock()
@@ -313,10 +325,11 @@ func (r *Runner) executeJob(job *api.NextJobResponse) (err error) {
 			r.encoder,
 			r.processes,
 			r.IsGPULockedOut(),
-			r.HasHIP(),
+			r.HasAMD(),
+			r.HasNVIDIA(),
+			r.HasIntel(),
 			r.GPUDetectionFailed(),
 			r.forceCPURendering,
-			r.disableHIPRT,
 			func() { r.SetGPULockedOut(true) },
 		)
 

internal/runner/tasks/encode.go

@@ -298,6 +298,9 @@ func (p *EncodeProcessor) Process(ctx *Context) error {
 				ctx.Info(line)
 			}
 		}
+		if err := scanner.Err(); err != nil {
+			log.Printf("Error reading encode stdout: %v", err)
+		}
 	}()
 
 	// Stream stderr
@@ -311,6 +314,9 @@ func (p *EncodeProcessor) Process(ctx *Context) error {
 				ctx.Warn(line)
 			}
 		}
+		if err := scanner.Err(); err != nil {
+			log.Printf("Error reading encode stderr: %v", err)
+		}
 	}()
 
 	err = cmd.Wait()

internal/runner/tasks/processor.go

@@ -11,8 +11,6 @@ import (
 	"jiggablend/pkg/executils"
 	"jiggablend/pkg/types"
 	"os/exec"
-	"strconv"
-	"strings"
 	"sync"
 	"time"
 )
@@ -43,23 +41,25 @@ type Context struct {
 
 	// GPULockedOut is set when the runner has detected a GPU error (e.g. HIP) and disables GPU for all jobs.
 	GPULockedOut bool
-	// HasHIP is true when the runner detected HIP (AMD) devices at startup. Used to force CPU for Blender < 4.x only when HIP is present.
-	HasHIP bool
-	// GPUDetectionFailed is true when startup GPU backend detection could not run; we force CPU for all versions (could not determine HIP vs NVIDIA).
+	// HasAMD is true when the runner detected AMD devices at startup.
+	HasAMD bool
+	// HasNVIDIA is true when the runner detected NVIDIA GPUs at startup.
+	HasNVIDIA bool
+	// HasIntel is true when the runner detected Intel GPUs (e.g. Arc) at startup.
+	HasIntel bool
+	// GPUDetectionFailed is true when startup GPU backend detection could not run; we force CPU for all versions (backend availability unknown).
 	GPUDetectionFailed bool
 	// OnGPUError is called when a GPU error line is seen in render logs; typically sets runner GPU lockout.
 	OnGPUError func()
 	// ForceCPURendering is a runner-level override that forces CPU rendering for all jobs.
 	ForceCPURendering bool
-	// DisableHIPRT is a runner-level override that disables HIPRT acceleration in Blender.
-	DisableHIPRT bool
 }
 
 // ErrJobCancelled indicates the manager-side job was cancelled during execution.
 var ErrJobCancelled = errors.New("job cancelled")
 
 // NewContext creates a new task context. frameEnd should be >= frame; if 0 or less than frame, it is treated as single-frame (frameEnd = frame).
-// gpuLockedOut is the runner's current GPU lockout state; hasHIP means the runner has HIP (AMD) devices (force CPU for Blender < 4.x only when true); gpuDetectionFailed means detection failed at startup (force CPU for all versions—could not determine HIP vs NVIDIA); onGPUError is called when a GPU error is detected in logs (may be nil).
+// gpuLockedOut is the runner's current GPU lockout state; gpuDetectionFailed means detection failed at startup (force CPU for all versions); onGPUError is called when a GPU error is detected in logs (may be nil).
 func NewContext(
 	taskID, jobID int64,
 	jobName string,
@@ -75,10 +75,11 @@ func NewContext(
 	encoder *encoding.Selector,
 	processes *executils.ProcessTracker,
 	gpuLockedOut bool,
-	hasHIP bool,
+	hasAMD bool,
+	hasNVIDIA bool,
+	hasIntel bool,
 	gpuDetectionFailed bool,
 	forceCPURendering bool,
-	disableHIPRT bool,
 	onGPUError func(),
 ) *Context {
 	if frameEnd < frameStart {
@@ -101,10 +102,11 @@ func NewContext(
 		Encoder:            encoder,
 		Processes:          processes,
 		GPULockedOut:       gpuLockedOut,
-		HasHIP:             hasHIP,
+		HasAMD:             hasAMD,
+		HasNVIDIA:          hasNVIDIA,
+		HasIntel:           hasIntel,
 		GPUDetectionFailed: gpuDetectionFailed,
 		ForceCPURendering:  forceCPURendering,
-		DisableHIPRT:       disableHIPRT,
 		OnGPUError:         onGPUError,
 	}
 }
@@ -187,8 +189,7 @@ func (c *Context) ShouldEnableExecution() bool {
 }
 
 // ShouldForceCPU returns true if GPU should be disabled and CPU rendering forced
-// (runner GPU lockout, GPU detection failed at startup for any version, metadata force_cpu,
-// or Blender < 4.x when the runner has HIP).
+// (runner GPU lockout, GPU detection failed at startup, or metadata force_cpu).
 func (c *Context) ShouldForceCPU() bool {
 	if c.ForceCPURendering {
 		return true
@@ -196,17 +197,10 @@ func (c *Context) ShouldForceCPU() bool {
 	if c.GPULockedOut {
 		return true
 	}
-	// Detection failed at startup: we could not determine HIP vs NVIDIA, so force CPU for all versions.
+	// Detection failed at startup: backend availability unknown, so force CPU for all versions.
 	if c.GPUDetectionFailed {
 		return true
 	}
-	v := c.GetBlenderVersion()
-	major := parseBlenderMajor(v)
-	isPre4 := v != "" && major >= 0 && major < 4
-	// Blender < 4.x: force CPU when runner has HIP (no official HIP support).
-	if isPre4 && c.HasHIP {
-		return true
-	}
 	if c.Metadata != nil && c.Metadata.RenderSettings.EngineSettings != nil {
 		if v, ok := c.Metadata.RenderSettings.EngineSettings["force_cpu"]; ok {
 			if b, ok := v.(bool); ok && b {
@@ -217,21 +211,6 @@ func (c *Context) ShouldForceCPU() bool {
 	return false
 }
 
-// parseBlenderMajor returns the major version number from a string like "4.2.3" or "3.6".
-// Returns -1 if the version cannot be parsed.
-func parseBlenderMajor(version string) int {
-	version = strings.TrimSpace(version)
-	if version == "" {
-		return -1
-	}
-	parts := strings.SplitN(version, ".", 2)
-	major, err := strconv.Atoi(parts[0])
-	if err != nil {
-		return -1
-	}
-	return major
-}
-
 // IsJobCancelled checks whether the manager marked this job as cancelled.
 func (c *Context) IsJobCancelled() (bool, error) {
 	if c.Manager == nil {

internal/runner/tasks/render.go

@@ -104,15 +104,10 @@ func (p *RenderProcessor) Process(ctx *Context) error {
 	renderFormat := "EXR"
 
 	if ctx.ShouldForceCPU() {
-		v := ctx.GetBlenderVersion()
-		major := parseBlenderMajor(v)
-		isPre4 := v != "" && major >= 0 && major < 4
 		if ctx.ForceCPURendering {
 			ctx.Info("Runner compatibility flag is enabled: forcing CPU rendering for this job")
 		} else if ctx.GPUDetectionFailed {
-			ctx.Info("GPU backend detection failed at startup—we could not determine whether this machine has HIP (AMD) or NVIDIA GPUs, so rendering will use CPU to avoid compatibility issues")
-		} else if isPre4 && ctx.HasHIP {
-			ctx.Info("Blender < 4.x has no official HIP support: using CPU rendering only")
+			ctx.Info("GPU backend detection failed at startup—we could not determine available GPU backends, so rendering will use CPU to avoid compatibility issues")
 		} else {
 			ctx.Info("GPU lockout active: using CPU rendering only")
 		}
@@ -195,7 +190,6 @@ func (p *RenderProcessor) createRenderScript(ctx *Context, renderFormat string)
 		settingsMap = make(map[string]interface{})
 	}
 	settingsMap["force_cpu"] = ctx.ShouldForceCPU()
-	settingsMap["disable_hiprt"] = ctx.DisableHIPRT
 	settingsJSON, err := json.Marshal(settingsMap)
 	if err == nil {
 		if err := os.WriteFile(renderSettingsFilePath, settingsJSON, 0644); err != nil {
@@ -277,6 +271,9 @@ func (p *RenderProcessor) runBlender(ctx *Context, blenderBinary, blendFile, out
 				}
 			}
 		}
+		if err := scanner.Err(); err != nil {
+			log.Printf("Error reading stdout: %v", err)
+		}
 	}()
 
 	// Stream stderr and watch for GPU error lines
@@ -297,6 +294,9 @@ func (p *RenderProcessor) runBlender(ctx *Context, blenderBinary, blendFile, out
 				}
 			}
 		}
+		if err := scanner.Err(); err != nil {
+			log.Printf("Error reading stderr: %v", err)
+		}
 	}()
 
 	// Wait for completion

internal/runner/workspace/archive.go

@@ -99,6 +99,11 @@ func ExtractTarStripPrefix(reader io.Reader, destDir string) error {
 
 		targetPath := filepath.Join(destDir, name)
 
+		// Sanitize path to prevent directory traversal
+		if !strings.HasPrefix(filepath.Clean(targetPath), filepath.Clean(destDir)+string(os.PathSeparator)) {
+			return fmt.Errorf("invalid file path in tar: %s", header.Name)
+		}
+
 		switch header.Typeflag {
 		case tar.TypeDir:
 			if err := os.MkdirAll(targetPath, os.FileMode(header.Mode)); err != nil {

internal/runner/workspace/archive_test.go

@@ -0,0 +1,101 @@
+package workspace
+
+import (
+	"archive/tar"
+	"bytes"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func createTarBuffer(files map[string]string) *bytes.Buffer {
+	var buf bytes.Buffer
+	tw := tar.NewWriter(&buf)
+	for name, content := range files {
+		hdr := &tar.Header{
+			Name: name,
+			Mode: 0644,
+			Size: int64(len(content)),
+		}
+		tw.WriteHeader(hdr)
+		tw.Write([]byte(content))
+	}
+	tw.Close()
+	return &buf
+}
+
+func TestExtractTar(t *testing.T) {
+	destDir := t.TempDir()
+
+	buf := createTarBuffer(map[string]string{
+		"hello.txt": "world",
+		"sub/a.txt": "nested",
+	})
+
+	if err := ExtractTar(buf, destDir); err != nil {
+		t.Fatalf("ExtractTar: %v", err)
+	}
+
+	data, err := os.ReadFile(filepath.Join(destDir, "hello.txt"))
+	if err != nil {
+		t.Fatalf("read hello.txt: %v", err)
+	}
+	if string(data) != "world" {
+		t.Errorf("hello.txt = %q, want %q", data, "world")
+	}
+
+	data, err = os.ReadFile(filepath.Join(destDir, "sub", "a.txt"))
+	if err != nil {
+		t.Fatalf("read sub/a.txt: %v", err)
+	}
+	if string(data) != "nested" {
+		t.Errorf("sub/a.txt = %q, want %q", data, "nested")
+	}
+}
+
+func TestExtractTarStripPrefix(t *testing.T) {
+	destDir := t.TempDir()
+
+	buf := createTarBuffer(map[string]string{
+		"toplevel/":        "",
+		"toplevel/foo.txt": "bar",
+	})
+
+	if err := ExtractTarStripPrefix(buf, destDir); err != nil {
+		t.Fatalf("ExtractTarStripPrefix: %v", err)
+	}
+
+	data, err := os.ReadFile(filepath.Join(destDir, "foo.txt"))
+	if err != nil {
+		t.Fatalf("read foo.txt: %v", err)
+	}
+	if string(data) != "bar" {
+		t.Errorf("foo.txt = %q, want %q", data, "bar")
+	}
+}
+
+func TestExtractTarStripPrefix_PathTraversal(t *testing.T) {
+	destDir := t.TempDir()
+
+	buf := createTarBuffer(map[string]string{
+		"prefix/../../../etc/passwd": "pwned",
+	})
+
+	err := ExtractTarStripPrefix(buf, destDir)
+	if err == nil {
+		t.Fatal("expected error for path traversal, got nil")
+	}
+}
+
+func TestExtractTar_PathTraversal(t *testing.T) {
+	destDir := t.TempDir()
+
+	buf := createTarBuffer(map[string]string{
+		"../../../etc/passwd": "pwned",
+	})
+
+	err := ExtractTar(buf, destDir)
+	if err == nil {
+		t.Fatal("expected error for path traversal, got nil")
+	}
+}