From 69446e77265a420c4f24a0395682212793eb323f Mon Sep 17 00:00:00 2001
From: Xuanru Li <157947275+xuanruli@users.noreply.github.com>
Date: Tue, 21 Jul 2026 19:39:03 -0700
Subject: [PATCH] Revert "feat(producer): renderStretch to re-time short
 compositions across longer scenes (#2676)" (#2730)

This reverts commit e786b78b3311d697e95269ec8fc21a4159af909d.
---
 packages/core/src/core.types.ts               | 12 --------
 packages/core/src/index.ts                    |  1 -
 .../src/outputFrameToTimelineSeconds.test.ts  | 30 -------------------
 packages/engine/src/services/frameCapture.ts  | 11 ++-----
 .../src/services/parallelCoordinator.ts       |  9 ++----
 packages/engine/src/types.ts                  |  2 --
 packages/producer/src/renderRequest.ts        | 12 --------
 packages/producer/src/server.ts               |  7 -----
 .../producer/src/services/distributed/plan.ts |  5 ----
 .../src/services/distributed/renderChunk.ts   |  3 --
 .../distributed/renderConfigValidation.ts     | 12 --------
 .../src/services/distributed/shared.ts        |  2 --
 .../render/stages/captureHdrHybridLoop.ts     |  3 +-
 .../render/stages/captureHdrSequentialLoop.ts |  3 +-
 .../services/render/stages/captureStage.ts    | 13 ++------
 .../render/stages/captureStreamingStage.ts    | 13 ++------
 .../services/render/stages/planHash.test.ts   | 20 -------------
 .../src/services/render/stages/planHash.ts    |  7 +----
 .../src/services/render/stages/probeStage.ts  |  7 ++---
 .../src/services/renderOrchestrator.ts        |  2 --
 20 files changed, 15 insertions(+), 159 deletions(-)
 delete mode 100644 packages/core/src/outputFrameToTimelineSeconds.test.ts

diff --git a/packages/core/src/core.types.ts b/packages/core/src/core.types.ts
index 402f43170..99d356b55 100644
--- a/packages/core/src/core.types.ts
+++ b/packages/core/src/core.types.ts
@@ -38,18 +38,6 @@ export function fpsToNumber(fps: Fps): number {
   return fps.num / fps.den;
 }
 
-/**
- * Timeline seek time for an output frame. `renderStretch` (=intrinsic/target,
- * default 1 = no-op) scales the mapping so a short comp spans a longer output.
- */
-export function outputFrameToTimelineSeconds(
-  frameIndex: number,
-  fps: Fps,
-  renderStretch = 1,
-): number {
-  return ((frameIndex * fps.den) / fps.num) * renderStretch;
-}
-
 /**
  * FFmpeg-style fps argument. Returns `"30"` for integer fps and `"30000/1001"`
  * for rationals — both forms are accepted verbatim by FFmpeg's `-r` and
diff --git a/packages/core/src/index.ts b/packages/core/src/index.ts
index 2ce7d2587..d99e932a7 100644
--- a/packages/core/src/index.ts
+++ b/packages/core/src/index.ts
@@ -63,7 +63,6 @@ export {
   parseFpsWithDefault,
   toFps,
   fpsToNumber,
-  outputFrameToTimelineSeconds,
   fpsToFfmpegArg,
   TIMELINE_COLORS,
   DEFAULT_DURATIONS,
diff --git a/packages/core/src/outputFrameToTimelineSeconds.test.ts b/packages/core/src/outputFrameToTimelineSeconds.test.ts
deleted file mode 100644
index de18361be..000000000
--- a/packages/core/src/outputFrameToTimelineSeconds.test.ts
+++ /dev/null
@@ -1,30 +0,0 @@
-import { describe, it, expect } from "vitest";
-import { outputFrameToTimelineSeconds } from "./core.types.js";
-
-describe("outputFrameToTimelineSeconds", () => {
-  const fps = { num: 30, den: 1 };
-
-  it("no-op when renderStretch is omitted (defaults to 1)", () => {
-    for (const i of [0, 1, 29, 143]) {
-      expect(outputFrameToTimelineSeconds(i, fps)).toBe((i * fps.den) / fps.num);
-    }
-  });
-
-  it("renderStretch=1 is byte-identical to the raw frame time", () => {
-    expect(outputFrameToTimelineSeconds(143, fps, 1)).toBe(143 / 30);
-  });
-
-  it("stretches a 1s comp across a 4.8s output (renderStretch = intrinsic/target)", () => {
-    const rs = 1 / 4.8;
-    expect(outputFrameToTimelineSeconds(0, fps, rs)).toBe(0);
-    // last of 144 output frames lands just under intrinsic 1.0s — never past it
-    const last = outputFrameToTimelineSeconds(143, fps, rs);
-    expect(last).toBeGreaterThan(0.98);
-    expect(last).toBeLessThan(1.0);
-  });
-
-  it("honors an exact rational fps (NTSC 30000/1001)", () => {
-    const ntsc = { num: 30000, den: 1001 };
-    expect(outputFrameToTimelineSeconds(30, ntsc, 1)).toBe((30 * 1001) / 30000);
-  });
-});
diff --git a/packages/engine/src/services/frameCapture.ts b/packages/engine/src/services/frameCapture.ts
index 576a07c99..0c7346dc7 100644
--- a/packages/engine/src/services/frameCapture.ts
+++ b/packages/engine/src/services/frameCapture.ts
@@ -2709,9 +2709,8 @@ export async function verifyStaticFramesSafe(
     if (last && f === last.b + 1) last.b = f;
     else runs.push({ a: f, b: f });
   }
-  const renderStretch = session.options.renderStretch ?? 1;
   const seekToFrame = async (frameIdx: number): Promise<void> => {
-    const t = quantizeTimeToFrame((frameIdx / fps) * renderStretch, fps);
+    const t = quantizeTimeToFrame(frameIdx / fps, fps);
     await page.evaluate((tt: number) => {
       const hf = (
         window as unknown as {
@@ -3649,14 +3648,11 @@ async function captureDeVerificationFrames(
   // their data-duration, and infinite-repeat GSAP reports a huge sentinel —
   // and indices derived from it would never be drained, silently disarming
   // verification for exactly the comps that need it.
-  // compositionDurationSeconds is already the output (drained) duration; the raw
-  // page fallback is intrinsic — divide it by renderStretch to match (1 = no-op).
-  const renderStretch = session.options.renderStretch ?? 1;
   const duration =
     session.options.compositionDurationSeconds ??
     (await page.evaluate(
       () => (window as unknown as { __hf?: { duration?: number } }).__hf?.duration ?? 0,
-    )) / renderStretch;
+    ));
   const totalFrames = Math.floor(duration * fps);
   if (totalFrames < 10) return;
   if (duration > 3600) {
@@ -3706,8 +3702,7 @@ async function captureDeVerificationFrames(
     while (boundary.has(idx) && guard++ < 6) idx = Math.min(totalFrames - 1, idx + 2);
     if (boundary.has(idx)) continue;
     if (frames.has(idx)) continue;
-    // Seek truth with the same ×renderStretch mapping the real capture uses for output frame idx.
-    const t = quantizeTimeToFrame((idx / fps) * renderStretch, fps);
+    const t = quantizeTimeToFrame(idx / fps, fps);
     await seekTo(t);
     // Video frame injection (same hook the real capture paths run) — without
     // it, <video> elements screenshot black and every video comp would
diff --git a/packages/engine/src/services/parallelCoordinator.ts b/packages/engine/src/services/parallelCoordinator.ts
index d6c028e4a..b52308886 100644
--- a/packages/engine/src/services/parallelCoordinator.ts
+++ b/packages/engine/src/services/parallelCoordinator.ts
@@ -23,7 +23,6 @@ import {
   type CapturePerfSummary,
   type BeforeCaptureHook,
 } from "./frameCapture.js";
-import { outputFrameToTimelineSeconds } from "@hyperframes/core";
 import { DEFAULT_CONFIG, type EngineConfig } from "../config.js";
 import { assertSwiftShader } from "../utils/assertSwiftShader.js";
 import { readWebGlVendorInfoFromCanvas } from "../utils/readWebGlVendorInfoFromCanvas.js";
@@ -369,10 +368,6 @@ async function captureFrameRange(
   let framesCaptured = 0;
   const outputOffset = task.outputFrameOffset ?? 0;
   const stride = task.frameStride ?? 1;
-  // Per-frame seek ×renderStretch maps frames across [0, intrinsic] (1 = no-op).
-  const renderStretch = captureOptions.renderStretch ?? 1;
-  const seekTime = (i: number): number =>
-    outputFrameToTimelineSeconds(i, captureOptions.fps, renderStretch);
   // Depth-2 pipelined drawElement produce (HF_DE_PARALLEL_STREAM spike): frame
   // k's in-page worker encode overlaps frame k+stride's produce phase — the
   // same shape as the sequential worker-encode loop. Only engaged when the
@@ -392,7 +387,7 @@ async function captureFrameRange(
     let prev: { idx: number; encodeResult: Promise<Buffer> } | null = null;
     for (let i = task.startFrame; i < task.endFrame; i += stride) {
       if (signal?.aborted) throw new Error("Parallel worker cancelled");
-      const time = seekTime(i);
+      const time = (i * captureOptions.fps.den) / captureOptions.fps.num;
       if (dbg && i < task.startFrame + dbgWin) {
         console.log(`[par:w${task.workerId}] +${Date.now() - dbgT0}ms produce ${i} start`);
       }
@@ -436,7 +431,7 @@ async function captureFrameRange(
   }
   for (let i = task.startFrame; i < task.endFrame; i += stride) {
     if (signal?.aborted) throw new Error("Parallel worker cancelled");
-    const time = seekTime(i);
+    const time = (i * captureOptions.fps.den) / captureOptions.fps.num;
     const fileFrameIdx = i - outputOffset;
 
     if (onFrameBuffer) {
diff --git a/packages/engine/src/types.ts b/packages/engine/src/types.ts
index 2716ab0a4..483a7b4de 100644
--- a/packages/engine/src/types.ts
+++ b/packages/engine/src/types.ts
@@ -115,7 +115,6 @@ export interface CaptureOptions {
    * timelines can outrun their declared duration). Consumers that derive
    * frame indices meant to be drained by the producer (drawElement
    * self-verification) MUST prefer this over `__hf.duration`.
-   * When renderStretch != 1 this is the OUTPUT (stretched) duration, not intrinsic.
    */
   compositionDurationSeconds?: number;
   /**
@@ -125,7 +124,6 @@ export interface CaptureOptions {
    * rational form verbatim — see `fpsToFfmpegArg`.
    */
   fps: Fps;
-  renderStretch?: number;
   format?: "jpeg" | "png";
   quality?: number;
   deviceScaleFactor?: number;
diff --git a/packages/producer/src/renderRequest.ts b/packages/producer/src/renderRequest.ts
index 4ea40abd8..e4e373aff 100644
--- a/packages/producer/src/renderRequest.ts
+++ b/packages/producer/src/renderRequest.ts
@@ -49,8 +49,6 @@ export interface RenderRequestOptions {
   variables?: Record<string, unknown>;
   outputResolution?: CanvasResolution;
   outputResolutionAspectAgnostic?: boolean;
-  /** intrinsic/target timeline re-time; 1 = no-op. Audio is silence-padded to output length, not time-stretched. */
-  renderStretch?: number;
   engineConfig: EngineConfig;
   distributed?: DistributedRenderOptions;
 }
@@ -107,13 +105,6 @@ function assertOptionalInteger(options: Record<string, unknown>, field: string,
   }
 }
 
-function assertOptionalPositiveNumber(options: Record<string, unknown>, field: string): void {
-  const value = options[field];
-  if (value !== undefined && (typeof value !== "number" || !Number.isFinite(value) || value <= 0)) {
-    throw new Error(`Render request ${field} must be a positive number`);
-  }
-}
-
 function assertOptionalString(options: Record<string, unknown>, field: string): void {
   if (options[field] !== undefined && typeof options[field] !== "string") {
     throw new Error(`Render request ${field} must be a string`);
@@ -169,7 +160,6 @@ function assertRequestOptionScalars(options: Record<string, unknown>): void {
   assertOptionalInteger(options, "gifLoop");
   assertOptionalInteger(options, "workers", 1);
   assertOptionalInteger(options, "crf");
-  assertOptionalPositiveNumber(options, "renderStretch");
   for (const field of ["useGpu", "debug", "outputResolutionAspectAgnostic"] as const) {
     assertOptionalBoolean(options, field);
   }
@@ -294,7 +284,6 @@ export function distributedConfigFromRequest(
     videoFrameFormat: options.videoFrameFormat,
     outputResolution: options.outputResolution,
     outputResolutionAspectAgnostic: options.outputResolutionAspectAgnostic,
-    renderStretch: options.renderStretch,
     chunkSize: distributed.chunkSize,
     maxParallelChunks: distributed.maxParallelChunks,
     targetChunkFrames: distributed.targetChunkFrames,
@@ -350,7 +339,6 @@ export function renderRequestFromDistributedConfig(input: {
     ...optionalProperty("videoFrameFormat", config.videoFrameFormat),
     ...optionalProperty("outputResolution", config.outputResolution),
     ...optionalProperty("outputResolutionAspectAgnostic", config.outputResolutionAspectAgnostic),
-    ...optionalProperty("renderStretch", config.renderStretch),
     ...optionalProperty("hdrMode", config.hdrMode),
     ...optionalProperty("strictness", config.strictness),
     ...optionalProperty("entryFile", config.entryFile),
diff --git a/packages/producer/src/server.ts b/packages/producer/src/server.ts
index 26d8d8a67..45af6b222 100644
--- a/packages/producer/src/server.ts
+++ b/packages/producer/src/server.ts
@@ -110,7 +110,6 @@ interface RenderInput {
    * compositions as an aspect-ratio mismatch.
    */
   outputResolutionAspectAgnostic?: boolean;
-  renderStretch?: number;
 }
 
 interface PreparedRenderInput {
@@ -168,10 +167,6 @@ export function parseRenderOptions(body: Record<string, unknown>): Omit<RenderIn
 
   const { variables, outputResolution, outputResolutionAspectAgnostic } =
     parseRenderOverrides(body);
-  const renderStretch =
-    typeof body.renderStretch === "number" && body.renderStretch > 0
-      ? body.renderStretch
-      : undefined;
 
   return {
     outputPath,
@@ -187,7 +182,6 @@ export function parseRenderOptions(body: Record<string, unknown>): Omit<RenderIn
     outputResolution,
     outputResolutionAspectAgnostic,
     videoFrameFormat,
-    renderStretch,
   };
 }
 
@@ -245,7 +239,6 @@ function buildRenderJobConfig(input: RenderInput, outputPath: string, log: Produ
       outputResolution: input.outputResolution,
       outputResolutionAspectAgnostic: input.outputResolutionAspectAgnostic,
       videoFrameFormat: input.videoFrameFormat,
-      renderStretch: input.renderStretch,
     },
   });
   return renderConfigFromRequest(request, { logger: log });
diff --git a/packages/producer/src/services/distributed/plan.ts b/packages/producer/src/services/distributed/plan.ts
index 084cc44fe..8f11d7bd5 100644
--- a/packages/producer/src/services/distributed/plan.ts
+++ b/packages/producer/src/services/distributed/plan.ts
@@ -135,9 +135,6 @@ export interface DistributedRenderConfig {
    */
   outputResolutionAspectAgnostic?: boolean;
 
-  /** intrinsic/target timeline re-time; 1 (or omitted) = no-op. Folded into planHash. */
-  renderStretch?: number;
-
   /**
    * Frames per chunk. When explicitly set, that value is used and
    * `chunkCount = min(maxParallelChunks, ceil(totalFrames / chunkSize))`
@@ -774,7 +771,6 @@ export async function plan(
     videoFrameFormat: config.videoFrameFormat,
     outputResolution: config.outputResolution,
     outputResolutionAspectAgnostic: config.outputResolutionAspectAgnostic,
-    renderStretch: config.renderStretch,
     // HDR is banned in distributed mode. force-sdr keeps the
     // extract / encoder paths off the HDR branches entirely.
     hdrMode: config.hdrMode ?? "force-sdr",
@@ -1041,7 +1037,6 @@ export async function plan(
     width,
     height,
     format: config.format,
-    renderStretch: config.renderStretch,
   };
   // Clean up the temp work tree BEFORE freezePlan. `.plan-work/` holds
   // intermediate compileStage + audio-mix artifacts (downloaded source
diff --git a/packages/producer/src/services/distributed/renderChunk.ts b/packages/producer/src/services/distributed/renderChunk.ts
index 3f1df3343..4f5009f15 100644
--- a/packages/producer/src/services/distributed/renderChunk.ts
+++ b/packages/producer/src/services/distributed/renderChunk.ts
@@ -239,7 +239,6 @@ interface PlanJson {
     width: number;
     height: number;
     format: DistributedFormat;
-    renderStretch?: number;
   };
   chunkCount: number;
   totalFrames: number;
@@ -516,8 +515,6 @@ export async function renderChunk(
       width: plan.dimensions.width,
       height: plan.dimensions.height,
       fps: { num: plan.dimensions.fpsNum, den: plan.dimensions.fpsDen },
-      // Per-frame seek ×renderStretch maps output frames across [0, intrinsic] (1 = no-op).
-      renderStretch: plan.dimensions.renderStretch ?? 1,
       format: plan.dimensions.format === "mp4" ? "jpeg" : "png",
       quality: plan.dimensions.format === "mp4" ? 80 : undefined,
       deviceScaleFactor: encoder.deviceScaleFactor,
diff --git a/packages/producer/src/services/distributed/renderConfigValidation.ts b/packages/producer/src/services/distributed/renderConfigValidation.ts
index a7b6297a6..261fc11d1 100644
--- a/packages/producer/src/services/distributed/renderConfigValidation.ts
+++ b/packages/producer/src/services/distributed/renderConfigValidation.ts
@@ -187,18 +187,6 @@ export function validateDistributedRenderConfig(
     }
   }
 
-  if (
-    config.renderStretch !== undefined &&
-    (typeof config.renderStretch !== "number" ||
-      !Number.isFinite(config.renderStretch) ||
-      config.renderStretch <= 0)
-  ) {
-    throw new InvalidConfigError(
-      "config.renderStretch",
-      `must be a positive number; got ${String(config.renderStretch)}`,
-    );
-  }
-
   if (config.runtimeCap !== undefined && !ALLOWED_RUNTIME_CAPS.includes(config.runtimeCap)) {
     throw new InvalidConfigError(
       "config.runtimeCap",
diff --git a/packages/producer/src/services/distributed/shared.ts b/packages/producer/src/services/distributed/shared.ts
index 4137a3f88..59932bca5 100644
--- a/packages/producer/src/services/distributed/shared.ts
+++ b/packages/producer/src/services/distributed/shared.ts
@@ -100,7 +100,6 @@ export interface SyntheticRenderJobInput {
   videoFrameFormat?: VideoFrameFormat;
   outputResolution?: RenderConfig["outputResolution"];
   outputResolutionAspectAgnostic?: RenderConfig["outputResolutionAspectAgnostic"];
-  renderStretch?: number;
   hdrMode: RenderConfig["hdrMode"];
   strictness?: RenderConfig["strictness"];
   entryFile: string;
@@ -125,7 +124,6 @@ export function buildSyntheticRenderJob(input: SyntheticRenderJobInput): RenderJ
     videoFrameFormat: input.videoFrameFormat,
     outputResolution: input.outputResolution,
     outputResolutionAspectAgnostic: input.outputResolutionAspectAgnostic,
-    renderStretch: input.renderStretch,
     // Distributed mode hard-pins to software GPU. The plan-time validator
     // refuses to fan out otherwise.
     useGpu: false,
diff --git a/packages/producer/src/services/render/stages/captureHdrHybridLoop.ts b/packages/producer/src/services/render/stages/captureHdrHybridLoop.ts
index 1e9992f6c..0c232da66 100644
--- a/packages/producer/src/services/render/stages/captureHdrHybridLoop.ts
+++ b/packages/producer/src/services/render/stages/captureHdrHybridLoop.ts
@@ -33,7 +33,6 @@ import {
   initTransparentBackground,
   initializeSession,
 } from "@hyperframes/engine";
-import { outputFrameToTimelineSeconds } from "@hyperframes/core";
 import type { FileServerHandle } from "../../fileServer.js";
 import type { ProducerLogger } from "../../../logger.js";
 import {
@@ -217,7 +216,7 @@ export async function runHybridLayeredFrameLoop(input: HybridLoopInput): Promise
       let nextRingIdx = 0;
       for (let i = range.start; i < range.end; i++) {
         assertNotAborted();
-        const time = outputFrameToTimelineSeconds(i, job.config.fps, job.config.renderStretch ?? 1);
+        const time = (i * job.config.fps.den) / job.config.fps.num;
         const activeTransition = transitionFramesSet.has(i)
           ? transitionRanges.find((t) => i >= t.startFrame && i <= t.endFrame)
           : undefined;
diff --git a/packages/producer/src/services/render/stages/captureHdrSequentialLoop.ts b/packages/producer/src/services/render/stages/captureHdrSequentialLoop.ts
index 96d16c4a2..19644eb8a 100644
--- a/packages/producer/src/services/render/stages/captureHdrSequentialLoop.ts
+++ b/packages/producer/src/services/render/stages/captureHdrSequentialLoop.ts
@@ -19,7 +19,6 @@ import {
   TRANSITIONS,
   crossfade,
 } from "@hyperframes/engine";
-import { outputFrameToTimelineSeconds } from "@hyperframes/core";
 import type { ProducerLogger } from "../../../logger.js";
 import {
   type HdrCompositeContext,
@@ -107,7 +106,7 @@ export async function runSequentialLayeredFrameLoop(input: SequentialLoopInput):
 
   for (let i = 0; i < totalFrames; i++) {
     assertNotAborted();
-    const time = outputFrameToTimelineSeconds(i, job.config.fps, job.config.renderStretch ?? 1);
+    const time = (i * job.config.fps.den) / job.config.fps.num;
     if (hdrPerf) hdrPerf.frames += 1;
 
     const stackingInfo = await seekInjectAndQueryStacking(
diff --git a/packages/producer/src/services/render/stages/captureStage.ts b/packages/producer/src/services/render/stages/captureStage.ts
index 02ca800d6..808b00bff 100644
--- a/packages/producer/src/services/render/stages/captureStage.ts
+++ b/packages/producer/src/services/render/stages/captureStage.ts
@@ -52,7 +52,6 @@ import {
   initializeSession,
   prepareCaptureSessionForReuse,
 } from "@hyperframes/engine";
-import { outputFrameToTimelineSeconds } from "@hyperframes/core";
 import type { FileServerHandle } from "../../fileServer.js";
 import type { ProducerLogger } from "../../../logger.js";
 import {
@@ -317,11 +316,7 @@ export async function runCaptureStage(input: CaptureStageInput): Promise<Capture
         for (let i = 0; i < rangeFrames; i++) {
           assertNotAborted();
           const absoluteIdx = rangeStart + i;
-          const time = outputFrameToTimelineSeconds(
-            absoluteIdx,
-            job.config.fps,
-            job.config.renderStretch ?? 1,
-          );
+          const time = (absoluteIdx * job.config.fps.den) / job.config.fps.num;
           const { encodeResult } = await captureFrameToBufferPipelined(session, i, time);
           await drainPrev();
           prev = { fileIndex: i, encodeResult };
@@ -331,11 +326,7 @@ export async function runCaptureStage(input: CaptureStageInput): Promise<Capture
         for (let i = 0; i < rangeFrames; i++) {
           assertNotAborted();
           const absoluteIdx = rangeStart + i;
-          const time = outputFrameToTimelineSeconds(
-            absoluteIdx,
-            job.config.fps,
-            job.config.renderStretch ?? 1,
-          );
+          const time = (absoluteIdx * job.config.fps.den) / job.config.fps.num;
           await captureFrame(session, i, time);
           reportFrame(i);
         }
diff --git a/packages/producer/src/services/render/stages/captureStreamingStage.ts b/packages/producer/src/services/render/stages/captureStreamingStage.ts
index c85acbb6f..364489fe2 100644
--- a/packages/producer/src/services/render/stages/captureStreamingStage.ts
+++ b/packages/producer/src/services/render/stages/captureStreamingStage.ts
@@ -71,7 +71,6 @@ import {
   prepareCaptureSessionForReuse,
   spawnStreamingEncoder,
 } from "@hyperframes/engine";
-import { outputFrameToTimelineSeconds } from "@hyperframes/core";
 import type { FileServerHandle } from "../../fileServer.js";
 import type { ProducerLogger } from "../../../logger.js";
 import type { ProgressCallback, RenderJob } from "../../renderOrchestrator.js";
@@ -406,8 +405,7 @@ async function runWorkerEncodePipelineLoop(
   abortSignal: AbortSignal | undefined,
 ): Promise<void> {
   let prev: { idx: number; encodeResult: Promise<Buffer> } | null = null;
-  const frameTime = (i: number) =>
-    outputFrameToTimelineSeconds(i, job.config.fps, job.config.renderStretch ?? 1);
+  const frameTime = (i: number) => (i * job.config.fps.den) / job.config.fps.num;
   const guard = createDrainFrameGuard({ log, stats, frameTime });
   const guardFrame = (idx: number, buf: Buffer): Promise<Buffer> => guard(session, idx, buf);
 
@@ -642,8 +640,7 @@ export async function runCaptureStreamingStage(
       const parallelGuard = createDrainFrameGuard({
         log,
         stats: parallelStats,
-        frameTime: (i: number) =>
-          outputFrameToTimelineSeconds(i, job.config.fps, job.config.renderStretch ?? 1),
+        frameTime: (i: number) => (i * job.config.fps.den) / job.config.fps.num,
       });
       let parallelGuardRan = false;
       // First guard/write failure aborts the reorder buffer so peer workers
@@ -838,11 +835,7 @@ export async function runCaptureStreamingStage(
           let lastProgressAt = Date.now();
           for (let i = 0; i < totalFrames; i++) {
             assertNotAborted();
-            const time = outputFrameToTimelineSeconds(
-              i,
-              job.config.fps,
-              job.config.renderStretch ?? 1,
-            );
+            const time = (i * job.config.fps.den) / job.config.fps.num;
             const { buffer } = await raceAgainstStall(
               captureFrameToBuffer(session, i, time),
               stallTimeoutMs - (Date.now() - lastProgressAt),
diff --git a/packages/producer/src/services/render/stages/planHash.test.ts b/packages/producer/src/services/render/stages/planHash.test.ts
index 8cab65164..2ecd5913f 100644
--- a/packages/producer/src/services/render/stages/planHash.test.ts
+++ b/packages/producer/src/services/render/stages/planHash.test.ts
@@ -251,23 +251,3 @@ describe("sha256Hex", () => {
     expect(sha256Hex(s)).toBe(sha256Hex(new TextEncoder().encode(s)));
   });
 });
-
-describe("computePlanHash — renderStretch byte-identity", () => {
-  const baseDims = { fpsNum: 30, fpsDen: 1, width: 1920, height: 1080, format: "mp4" as const };
-
-  it("renderStretch=1 and undefined hash identically to a pre-renderStretch plan", () => {
-    const omitted = computePlanHash(makeInput({ dimensions: { ...baseDims } }));
-    const one = computePlanHash(makeInput({ dimensions: { ...baseDims, renderStretch: 1 } }));
-    const undef = computePlanHash(
-      makeInput({ dimensions: { ...baseDims, renderStretch: undefined } }),
-    );
-    expect(one).toBe(omitted);
-    expect(undef).toBe(omitted);
-  });
-
-  it("a stretched plan (renderStretch=2) gets a distinct hash", () => {
-    const base = computePlanHash(makeInput({ dimensions: { ...baseDims } }));
-    const stretched = computePlanHash(makeInput({ dimensions: { ...baseDims, renderStretch: 2 } }));
-    expect(stretched).not.toBe(base);
-  });
-});
diff --git a/packages/producer/src/services/render/stages/planHash.ts b/packages/producer/src/services/render/stages/planHash.ts
index 2d49e7209..127db7c24 100644
--- a/packages/producer/src/services/render/stages/planHash.ts
+++ b/packages/producer/src/services/render/stages/planHash.ts
@@ -73,8 +73,6 @@ export interface PlanDimensions {
   width: number;
   height: number;
   format: DistributedFormat;
-  /** intrinsic/target timeline re-time; 1 (or omitted) = no-op, hashed identically to today. */
-  renderStretch?: number;
 }
 
 export interface PlanHashInput {
@@ -129,10 +127,7 @@ export function computePlanHash(input: PlanHashInput): string {
   hash.update(FIELD_DELIMITER);
 
   const d = input.dimensions;
-  // Append renderStretch only when it re-times (!= 1) so unstretched plans hash identically to before.
-  const stretchSuffix =
-    d.renderStretch !== undefined && d.renderStretch !== 1 ? `x${d.renderStretch}` : "";
-  hash.update(`${d.fpsNum}/${d.fpsDen}x${d.width}x${d.height}x${d.format}${stretchSuffix}`, "utf8");
+  hash.update(`${d.fpsNum}/${d.fpsDen}x${d.width}x${d.height}x${d.format}`, "utf8");
 
   return hash.digest("hex");
 }
diff --git a/packages/producer/src/services/render/stages/probeStage.ts b/packages/producer/src/services/render/stages/probeStage.ts
index 011ccd308..3e9f3b158 100644
--- a/packages/producer/src/services/render/stages/probeStage.ts
+++ b/packages/producer/src/services/render/stages/probeStage.ts
@@ -592,10 +592,7 @@ export async function runProbeStage(input: ProbeStageInput): Promise<ProbeStageR
   const browserProbeMs = Date.now() - probeStart;
 
   const duration = composition.duration;
-  // Output length = intrinsic / renderStretch (1 = no-op); composition.duration stays intrinsic.
-  const renderStretch = job.config.renderStretch ?? 1;
-  const outputDuration = duration / renderStretch;
-  const totalFrames = durationToFrameCount(outputDuration, fpsToNumber(job.config.fps));
+  const totalFrames = durationToFrameCount(duration, fpsToNumber(job.config.fps));
 
   if (duration <= 0) {
     // Gather diagnostics to help users understand why the render would produce a black video.
@@ -664,7 +661,7 @@ export async function runProbeStage(input: ProbeStageInput): Promise<ProbeStageR
     fileServer,
     probeSession,
     lastBrowserConsole,
-    duration: outputDuration,
+    duration,
     totalFrames,
     browserProbeMs,
     beginFrameStalled,
diff --git a/packages/producer/src/services/renderOrchestrator.ts b/packages/producer/src/services/renderOrchestrator.ts
index bcb6efcbf..e8d37dbf9 100644
--- a/packages/producer/src/services/renderOrchestrator.ts
+++ b/packages/producer/src/services/renderOrchestrator.ts
@@ -364,7 +364,6 @@ export interface RenderConfig {
    * alias (`1080p-portrait`). Explicit orientation presets stay strict.
    */
   outputResolutionAspectAgnostic?: boolean;
-  renderStretch?: number;
 }
 
 export interface RenderPerfSummary {
@@ -2190,7 +2189,6 @@ async function executeRenderPipeline(input: {
       width,
       height,
       fps: job.config.fps,
-      renderStretch: job.config.renderStretch ?? 1,
       format: needsAlpha ? "png" : "jpeg",
       quality: needsAlpha ? undefined : job.config.quality === "draft" ? 80 : 95,
       variables: job.config.variables,