fix(cli,producer): cross-multiply aspect check, CLI HDR guard, honest banner

packages/cli/src/commands/render.test.ts

@@ -207,6 +207,35 @@ describe("renderLocal browser GPU config", () => {
     expect(producerState.createdJobs[0]?.entryFile).toBeUndefined();
   });
 
+  it("forwards outputResolution to createRenderJob when --resolution is set", async () => {
+    await renderLocal("/tmp/project", "/tmp/out.mp4", {
+      fps: 30,
+      quality: "standard",
+      format: "mp4",
+      gpu: false,
+      browserGpuMode: "software",
+      hdrMode: "auto",
+      quiet: true,
+      outputResolution: "landscape-4k",
+    });
+
+    expect(producerState.createdJobs[0]?.outputResolution).toBe("landscape-4k");
+  });
+
+  it("omits outputResolution from createRenderJob by default", async () => {
+    await renderLocal("/tmp/project", "/tmp/out.mp4", {
+      fps: 30,
+      quality: "standard",
+      format: "mp4",
+      gpu: false,
+      browserGpuMode: "software",
+      hdrMode: "auto",
+      quiet: true,
+    });
+
+    expect(producerState.createdJobs[0]?.outputResolution).toBeUndefined();
+  });
+
   it("can force the CLI process to exit after a successful local render", async () => {
     vi.useFakeTimers();
     const exit = vi

packages/cli/src/commands/render.ts

@@ -253,6 +253,18 @@ export default defineCommand({
         );
         process.exit(1);
       }
+      // Reject the --resolution + --hdr combination at the CLI layer so the
+      // user sees the friendly errorBox before any work directories or
+      // ffmpeg processes spin up. The orchestrator also enforces this via
+      // resolveDeviceScaleFactor — defense in depth.
+      if (args.hdr) {
+        errorBox(
+          "Conflicting flags",
+          "--resolution cannot be combined with --hdr. The HDR pipeline composites at composition dimensions and does not yet support supersampling.",
+          "Render in two passes: HDR at composition resolution, then upscale separately with ffmpeg.",
+        );
+        process.exit(1);
+      }
     }
 
     // ── Validate workers ──────────────────────────────────────────────────
@@ -369,7 +381,11 @@ export default defineCommand({
       );
       console.log(c.dim("   " + fps + "fps \u00B7 " + quality + " \u00B7 " + workerLabel));
       if (outputResolution) {
-        console.log(c.dim("   Output resolution: " + outputResolution + " (supersampled via DPR)"));
+        // Don't claim "supersampled" — when the composition is already at the
+        // target dimensions, the DPR resolves to 1 and no supersampling
+        // happens. We don't have the composition's dims at this point in the
+        // CLI, so describe the intent rather than the mechanism.
+        console.log(c.dim("   Output resolution: " + outputResolution));
       }
       if (useGpu || browserGpuMode !== "software") {
         const gpuModes = [

packages/producer/src/services/renderOrchestrator.ts

@@ -616,9 +616,11 @@ export function resolveDeviceScaleFactor(input: {
     );
   }
   const target = CANVAS_DIMENSIONS[input.outputResolution];
-  const widthRatio = target.width / input.compositionWidth;
-  const heightRatio = target.height / input.compositionHeight;
-  if (widthRatio !== heightRatio) {
+  // Aspect-ratio compare via cross-multiplication so the equality is integer-
+  // safe. Float division (`target.width / compositionWidth`) loses precision
+  // for non-power-of-2 ratios (e.g. cinema 4K 4096×2160 = 1.8963…) and a
+  // future preset could trip a false-mismatch on otherwise valid input.
+  if (target.width * input.compositionHeight !== target.height * input.compositionWidth) {
     throw new Error(
       `outputResolution ${input.outputResolution} (${target.width}×${target.height}) ` +
         `does not match the aspect ratio of the composition ` +
@@ -626,6 +628,8 @@ export function resolveDeviceScaleFactor(input: {
         `Pick a preset whose orientation matches.`,
     );
   }
+  // Aspect ratios match → widthRatio === heightRatio. Compute once.
+  const widthRatio = target.width / input.compositionWidth;
   if (widthRatio < 1) {
     throw new Error(
       `outputResolution ${input.outputResolution} (${target.width}×${target.height}) ` +