From bb86412664235be2b8b4584c21f6ffe7b404cf2d Mon Sep 17 00:00:00 2001
From: Alex-Wengg <hanweng9@gmail.com>
Date: Tue, 15 Sep 2026 16:25:04 -0400
Subject: [PATCH 1/2] docs(acestep): register packed INT8 runtime

---
 packages/acestep/optimization/LEDGER.md       |  3 +-
 .../OPT-0091-packed-int8-dit-runtime.md       | 72 +++++++++++++++++++
 2 files changed, 74 insertions(+), 1 deletion(-)
 create mode 100644 packages/acestep/optimization/experiments/OPT-0091-packed-int8-dit-runtime.md

diff --git a/packages/acestep/optimization/LEDGER.md b/packages/acestep/optimization/LEDGER.md
index dacfe27..6af690c 100644
--- a/packages/acestep/optimization/LEDGER.md
+++ b/packages/acestep/optimization/LEDGER.md
@@ -3,7 +3,7 @@
 Stage 2 was explicitly authorized on 2026-08-13. The approved baseline is
 frozen and measured optimization is active.
 
-Next available ID: `OPT-0091`.
+Next available ID: `OPT-0092`.
 
 | ID | Subsystem | Hypothesis | Evidence | Disposition | Result | Record | Implementation |
 | --- | --- | --- | --- | --- | --- | --- | --- |
@@ -97,6 +97,7 @@ Next available ID: `OPT-0091`.
 | OPT-0088 | Portable device support | Every subgroup-dependent production owner (OPT-0032/0037 dense K4, OPT-0051 K7 row-reuse, OPT-0048 ConvTranspose K4, attention query8/quad-query) can gain a workgroup-memory counterpart consuming the unchanged hosted packages, selected by the existing execution-profile machinery, so adapters without `subgroups` (Safari, Firefox, iOS) run the production graph instead of failing `FEATURE_UNAVAILABLE`; compatibility experiment, bounded slowdown expected and reported, `shader-f16` stays fail-closed | pending | pending-integration | Portable dense/K7/ConvTranspose owners landed with test-enforced bit-identical arithmetic (byte-equal WGSL arithmetic sections, re-exported rev7/rev8 index math); attention routes to the existing portable oracle (reordered-rounding vs subgroup reduction). End-to-end masked-subgroups waveform and timing gates pending | [record](experiments/OPT-0088-portable-no-subgroup-production-path.md) | kernels c272b2d/c48c050/373e90a; selection wiring pending |
 | OPT-0089 | DiT weight quantization | Weight-only symmetric int8 (per-32-K-block fp16 scales, round-to-nearest, clamp ±127) fake-quantization of all 264 rev7 DiT GEMM tensors, dequantized in place and run through the completely unchanged production graph, preserves end-to-end 30 s waveform quality within a small numerical envelope, so an int8-resident DiT (~1.51 GB + scales) is a credible answer to the observed iPhone 17 Safari OOM kill at `1,789,925,376 / 3,020,808,192` uploaded bytes (layer 14/24); pure quantization-damage gate, zero kernel changes, distinct mechanism from abandoned OPT-0058 activation-quantized DP4a | positive | benchmark-only | Per-tensor damage uniform and small: NRMSE `0.00515–0.00634` (median `0.00559`), min SNR `43.96 dB`, no outlier tensor/family, so no fp16-retention map needed. Determinism gate reproduced the pinned fp16 baseline WAV byte-exactly, then fake-quant vs fp16 on identical seeds gave lo-fi/12345 waveform NRMSE `0.0669` (Pearson `0.99777`, LSD ≈`3.5 dB`, RMS Δ `−0.050 dB`) and latin/424242 NRMSE `0.2268` (Pearson `0.97460`, LSD ≈`4.7 dB`, RMS Δ `+0.089 dB`; per-second max `5.19` is a near-silent-ending small-denominator artifact) — trajectory divergence of the 8-evaluation sampler, not noise-like corruption; zero non-finite samples and exact peak parity. Projected int8 DiT phase peak ≈`1.862 GB` tracked GPU (`1.51 GB` int8 + `94 MB` scales + fp16 norms/shared + measured `127 MB` overhead) versus the observed iPhone 17 kill at ≈`1.920 GB` — plausibly fits, marginal ≈`58 MB` margin; int8 kernel work justified, listening gate mandatory before any product claim | [record](experiments/OPT-0089-dit-int8-weight-fake-quant-gate.md), [quant result](results/OPT-0089/quant-error.json), [waveform result](results/OPT-0089/waveform-metrics.json) | `scripts/requantize-dit-int8.py` (repo root); fake-quant package `ef8355b9…` (models-local, not hosted); benchmark-only, no kernel or production change |
 | OPT-0090 | DiT quantization listening preview | The authenticated OPT-0089 fake-quant package can be exposed as an explicit opt-in listening comparison without changing the production default, weakening package identity checks, or claiming packed-int8 size/runtime benefits | positive | integrated | Reproduced the recorded `ef8355b9…` package and byte-identical quant report, published the immutable full-size artifact, then added an Advanced listening selector with orderly model switching and explicit size/non-production disclosure. 43 web integration, 4 unit, and 2,029 ACE tests plus typecheck, formatting, production build, and all PR checks passed; fresh browser/GPU listening remains external | [record](experiments/OPT-0090-int8-quality-preview.md) | implementation `2816d6b83185cbde5abd6780a9f5ac903a655154`; artifact `ac50b5c854fb044ce058acb91d4cd9ab82d99cfa` |
+| OPT-0091 | Packed weight-only INT8 DiT runtime | Keep the 216 repeated-layer dense matrices as signed INT8 with per-output/K32 FP16 scales and dequantize inside subgroup and portable kernels, preserving the current activation rounding and increasing-K FP32 accumulation while materially reducing the 3.02 GB DiT package | pending | benchmark-only | Registered before implementation; converter, package, primitive, graph, browser, listening, and deployment gates remain open. This does not reuse OPT-0058 dynamic activation quantization | [record](experiments/OPT-0091-packed-int8-dit-runtime.md) | allocation `083c68ca7ad9031c41ec4a9faa9a1561d190f63e`; no implementation yet |
 
 Experiment IDs are allocated before code changes, never reused, and never
 removed from this table.
diff --git a/packages/acestep/optimization/experiments/OPT-0091-packed-int8-dit-runtime.md b/packages/acestep/optimization/experiments/OPT-0091-packed-int8-dit-runtime.md
new file mode 100644
index 0000000..a1d6dd3
--- /dev/null
+++ b/packages/acestep/optimization/experiments/OPT-0091-packed-int8-dit-runtime.md
@@ -0,0 +1,72 @@
+# OPT-0091 — Packed weight-only INT8 DiT runtime
+
+## Status
+
+- Evidence: `pending`
+- Disposition: `benchmark-only`
+- Date: 2026-09-15
+- Risk class: `approximate` model weights, unchanged activations and FP32
+  accumulation
+
+## Motivation
+
+The OPT-0090 listening preview stores quantized values after dequantizing them
+back into the original FP16/BF16 package. It therefore still downloads the full
+5.75 GB cold model set and does not answer the reported download-size problem.
+OPT-0089 established only that per-K32 weight quantization is numerically
+credible; it explicitly left packed storage and kernels unimplemented.
+
+## Hypothesis
+
+The 216 repeated-layer DiT dense matrices can remain packed as signed INT8 with
+one FP16 scale per output and K32 block, then be dequantized at load use inside
+fixed32-subgroup and portable WebGPU kernels. Keeping activations at their
+current FP16 load boundary and accumulation in increasing-K FP32 order should
+match the OPT-0089 fake-quant arithmetic closely while reducing the 3.02 GB
+mixed DiT package materially. The 48 cross-attention K/V matrices remain in
+their accepted packed-BF16 representation in this first complete runtime.
+
+This is weight-only quantization and does not revisit OPT-0058's rejected
+dynamic activation quantization or DP4A contraction.
+
+## Frozen package and arithmetic contract
+
+- Source: authenticated production revision-7 DiT manifest
+  `d3fc0020efcf60702db411da2fd4b93e9bb84f1437ed310aef01c892727e452f`.
+- Quantization: symmetric signed INT8, K block 32, FP16 scale
+  `max(abs(weight))/127`, round-to-nearest-even, clamp to `[-127, 127]`, and
+  canonical zero-scale blocks.
+- Physical tensor layout: for each existing N256/K32 tile, contiguous packed
+  signed bytes followed by its 256 FP16 scales. Tensor records remain
+  independently aligned and bound.
+- Activation values retain the current FP32-to-FP16 load rounding. Each INT8
+  value is multiplied by its FP16 block scale, widened to FP32, and accumulated
+  in ascending K order into the existing FP32 output.
+- Production FP16 manifests, runtime, and default selection remain unchanged.
+
+## Gates
+
+1. Converter: deterministic bytes from the pinned source, complete source and
+   tensor accounting, exact declared layout/size, bounded memory, transactional
+   output, independent package verification, and rejection of malformed scale,
+   offset, dtype, layout, or identity records.
+2. Primitive: all four production dense shapes plus boundary rows, zero blocks,
+   signed extrema, deterministic repeats, complete writes, finite outputs, and
+   cleanup. Compare subgroup and portable owners against CPU fake-quant and the
+   existing FP16 owner; record max error, NRMSE, SNR, and correlation.
+3. Package-native graph: exact package identity, all 24 layers, every sampler
+   tap, final latent, cancellation, cache recovery, resource lifetime, and
+   absence of device loss or non-finite values.
+4. Product: at least one 30-second default Latin instrumental using a fixed
+   seed, valid WAV, waveform metrics against OPT-0089, and human listening
+   before describing quality as approved.
+5. Delivery: published artifact bytes and manifest re-downloaded and hashed,
+   CORS for the GitHub Pages origin verified, UI reports measured download
+   bytes, all repository checks pass, and the exact Pages deployment is
+   inspected after merge.
+
+## Current result
+
+Registered before implementation. No compressed package, kernel, browser run,
+quality approval, download reduction, mobile-support, or production claim is
+made yet.

From c404e94ad250cb6d2da001d237b442329c7ab876 Mon Sep 17 00:00:00 2001
From: Alex-Wengg <hanweng9@gmail.com>
Date: Tue, 15 Sep 2026 17:04:23 -0400
Subject: [PATCH 2/2] feat(acestep): add packed INT8 music preview

---
 README.md                                     |   4 +-
 music.html                                    |  12 +-
 packages/acestep/README.md                    |   5 +-
 packages/acestep/model/README.md              |   8 +
 packages/acestep/model/repack_dit_int8.py     | 210 ++++++++++
 .../model/tests/test_repack_dit_int8.py       |  40 ++
 packages/acestep/optimization/LEDGER.md       |   2 +-
 .../OPT-0091-packed-int8-dit-runtime.md       |  17 +-
 .../optimization/results/OPT-0091/result.json |  31 ++
 packages/acestep/src/model/manifest.ts        | 105 +++--
 packages/acestep/src/runtime/diagnostics.ts   |  11 +-
 packages/acestep/src/runtime/protocol.ts      |  45 ++-
 .../acestep/src/runtime/webgpu-pipeline.ts    |  93 ++++-
 .../acestep/src/webgpu/ace-dit-package.ts     |  26 +-
 packages/acestep/src/webgpu/ace-dit.ts        |  16 +
 packages/acestep/src/webgpu/dit-backend.ts    |  53 ++-
 .../acestep/src/webgpu/dit-fp16-package.ts    |  42 ++
 packages/acestep/src/webgpu/dit-graph.ts      |   8 +-
 .../kernels/dit-dense-int8-weight-only.ts     | 359 ++++++++++++++++++
 packages/acestep/src/webgpu/kernels/gemm.ts   |   2 +
 .../opt-0010-planner-token-profiler.test.ts   |   6 +
 ...-compact-semantic-head-ab-contract.test.ts |   5 +-
 .../opt-0012-compact-semantic-head.test.ts    |   7 +-
 .../test/opt-0077-result-contract.test.ts     |   2 +-
 .../test/opt-0078-result-contract.test.ts     |   2 +-
 .../test/opt-0079-result-contract.test.ts     |   2 +-
 .../opt-0081-registration-contract.test.ts    |   2 +-
 .../opt-0090-int8-quality-preview.test.ts     |   7 +
 .../test/opt-0091-packed-int8-runtime.test.ts | 101 +++++
 src/engines/musicgen-acestep/config.ts        |  11 +-
 .../model-download-progress.ts                |  37 +-
 src/music.ts                                  |  35 +-
 test/music-model-download-progress.test.ts    |  35 ++
 test/music-model-variant.test.ts              |  20 +-
 test/music-preparation.test.ts                |   3 +
 35 files changed, 1252 insertions(+), 112 deletions(-)
 create mode 100644 packages/acestep/model/repack_dit_int8.py
 create mode 100644 packages/acestep/model/tests/test_repack_dit_int8.py
 create mode 100644 packages/acestep/optimization/results/OPT-0091/result.json
 create mode 100644 packages/acestep/src/webgpu/kernels/dit-dense-int8-weight-only.ts
 create mode 100644 packages/acestep/test/opt-0091-packed-int8-runtime.test.ts
 create mode 100644 test/music-model-download-progress.test.ts

diff --git a/README.md b/README.md
index c58be7a..f69f566 100644
--- a/README.md
+++ b/README.md
@@ -40,8 +40,8 @@ the downloaded model.
 
 The site uses ACE-Step 1.5 Turbo in direct mode. The optional planner is
 available in the underlying runtime but disabled on the public music page.
-Advanced settings includes a full-size, experimental INT8 quality preview for
-listening comparisons; it does not yet provide a smaller download.
+Advanced settings includes an experimental packed INT8 preview. Its DiT is
+1.70 GB instead of 3.02 GB (43.7% smaller) for listening comparisons.
 See the [ACE-Step README](packages/acestep/README.md) for implementation and
 validation details.
 
diff --git a/music.html b/music.html
index 82d6897..fc63698 100644
--- a/music.html
+++ b/music.html
@@ -219,12 +219,14 @@ <h1>ACE-Step 1.5</h1>
                 Model
                 <select id="model-variant" name="model-variant">
                   <option value="production" selected>Production (recommended)</option>
-                  <option value="int8-quality-preview">INT8 quality preview (experimental)</option>
+                  <option id="int8-model-option" value="int8-quality-preview" hidden>
+                    Compressed INT8 preview (experimental)
+                  </option>
                 </select>
-                <small>
-                  The preview tests audible quantization effects but is not compressed.
-                  It is also 5.75 GB; switching from a cached production model adds a
-                  separate 3.02 GB DiT download. Use the same seed to compare.
+                <small id="int8-model-hint" hidden>
+                  The preview uses a 1.70 GB packed INT8 DiT instead of the
+                  3.02 GB production DiT (43.7% smaller). Switching models downloads
+                  a separate DiT package. Use the same seed to compare quality.
                 </small>
               </label>
             </div>
diff --git a/packages/acestep/README.md b/packages/acestep/README.md
index accba55..c9c9454 100644
--- a/packages/acestep/README.md
+++ b/packages/acestep/README.md
@@ -18,8 +18,9 @@ have a portable fallback. Source-audio editing, cover generation, and the VAE
 encoder are outside the current scope. Support for phones and other browsers
 must be validated on the target device.
 
-The FluidAudio music page uses direct generation and a **5.75 GB** model cache.
-Its planner is disabled. The package's development demo also exposes the
+The FluidAudio music page uses direct generation and a **5.75 GB** production
+model cache. Its optional packed INT8 preview uses **4.43 GB**. The planner is
+disabled. The package's development demo also exposes the
 planner and uses a different reference manifest. The site's selected model
 packages are defined in [config.ts](../../src/engines/musicgen-acestep/config.ts).
 
diff --git a/packages/acestep/model/README.md b/packages/acestep/model/README.md
index e85c801..9181d06 100644
--- a/packages/acestep/model/README.md
+++ b/packages/acestep/model/README.md
@@ -8,6 +8,9 @@ manifest, verifies the result independently, and atomically installs it. No
 notebook, manually edited weight, or unrecorded shell step is part of the
 package recipe.
 
+`repack_dit_int8.py` is the deterministic OPT-0091 derivative step. It accepts
+only the exact revision-7 DiT package and emits the packed INT8 preview.
+
 The structure deliberately follows `../parakeet.wgsl/model`, pinned at
 Parakeet commit `7ee112738262a6f5a0efd2f150748a4087432fbb`. ACE-Step has a
 larger staged graph, so its source contracts and phase-oriented shard plan are
@@ -55,6 +58,11 @@ uv run --frozen --project model --python 3.13 \
 # the authenticated revision-7 package after complete staging verification.
 uv run --frozen --project model --python 3.13 \
   python3 model/convert.py --profile fp16-dit-dense-experimental --offline
+
+# OPT-0091 packed INT8 preview from the authenticated revision-7 DiT package.
+uv run --frozen --project model --python 3.13 \
+  python3 model/repack_dit_int8.py \
+  model/files-fp16-dit-rev7-oracle model/files-int8-dit-rev9
 ```
 
 `--profile production` downloads and authenticates the pinned upstream files,
diff --git a/packages/acestep/model/repack_dit_int8.py b/packages/acestep/model/repack_dit_int8.py
new file mode 100644
index 0000000..cd416fa
--- /dev/null
+++ b/packages/acestep/model/repack_dit_int8.py
@@ -0,0 +1,210 @@
+"""Create the authenticated OPT-0091 packed-INT8 DiT runtime package.
+
+The input is the exact revision-7 mixed DiT package. Only the 216 repeated
+dense matrices are repacked; cross-attention K/V and support tensors retain
+their authenticated BF16 storage.
+"""
+
+from __future__ import annotations
+
+import argparse
+import hashlib
+import json
+import os
+import tempfile
+from pathlib import Path
+
+import numpy as np
+
+SOURCE_MANIFEST_SHA256 = (
+    "d3fc0020efcf60702db411da2fd4b93e9bb84f1437ed310aef01c892727e452f"
+)
+SOURCE_LAYOUT = "dit-gemm-n256-k32-tile-major-v1"
+SOURCE_TRANSFORMATION = "bf16-to-ieee-fp16-dit-gemm-n256-k32-tile-major-v1"
+PACKED_LAYOUT = "dit-gemm-n256-k32-int8-fp16-scale-tile-major-v1"
+PACKED_TRANSFORMATION = (
+    "bf16-to-symmetric-int8-fp16-scale-n256-k32-tile-major-v1"
+)
+PACKED_DTYPE = "uint32-int8-fp16-blocks"
+PACKED_WORDS_PER_TILE = 2_176
+EXPECTED_DENSE_TENSORS = 216
+EXPECTED_WEIGHT_BYTES = 1_699_602_432
+
+
+def _canonical_json(value: object) -> bytes:
+    return (
+        json.dumps(value, ensure_ascii=False, separators=(",", ":"), sort_keys=True)
+        .encode("utf-8")
+        + b"\n"
+    )
+
+
+def _sha256(payload: bytes) -> str:
+    return hashlib.sha256(payload).hexdigest()
+
+
+def _verify_runtime_files(directory: Path, manifest: dict[str, object]) -> None:
+    for record in manifest["files"]:
+        if record["kind"] != "weights":
+            continue
+        path = directory / record["name"]
+        payload = path.read_bytes()
+        if len(payload) != record["byteLength"] or _sha256(payload) != record["sha256"]:
+            raise ValueError(f"packed shard identity changed: {record['name']}")
+
+
+def pack_dense_tensor(payload: bytes, shape: list[int]) -> tuple[bytes, list[int]]:
+    """Pack one rev7 [N,K] FP16 tile-major matrix deterministically."""
+
+    if len(shape) != 2:
+        raise ValueError("packed INT8 dense tensor must be rank two")
+    columns, inner = shape
+    if columns % 256 != 0 or inner % 32 != 0:
+        raise ValueError("packed INT8 dense dimensions must divide N256/K32")
+    expected_bytes = columns * inner * 2
+    if len(payload) != expected_bytes:
+        raise ValueError("packed INT8 source tensor byte length changed")
+
+    tiles = np.frombuffer(payload, dtype="<f2").reshape(
+        columns // 256, inner // 32, 32, 256
+    )
+    output = bytearray()
+    for column_tile in range(columns // 256):
+        for inner_tile in range(inner // 32):
+            values = tiles[column_tile, inner_tile].astype(np.float32)
+            scales = (np.max(np.abs(values), axis=0) / np.float32(127.0)).astype(
+                "<f2"
+            )
+            divisors = scales.astype(np.float32)
+            divisors = np.where(divisors == 0.0, np.float32(1.0), divisors)
+            quantized = np.clip(
+                np.rint(values / divisors[None, :]), -127, 127
+            ).astype(np.int8)
+            output.extend(quantized.tobytes(order="C"))
+            output.extend(scales.tobytes(order="C"))
+
+    storage_shape = [columns // 256, inner // 32, PACKED_WORDS_PER_TILE]
+    if len(output) != np.prod(storage_shape, dtype=np.int64) * 4:
+        raise ValueError("packed INT8 tensor storage shape changed")
+    return bytes(output), storage_shape
+
+
+def repack(source: Path, output_root: Path) -> tuple[Path, dict[str, int | str]]:
+    source_manifest_bytes = (source / "manifest.json").read_bytes()
+    if _sha256(source_manifest_bytes) != SOURCE_MANIFEST_SHA256:
+        raise ValueError("OPT-0091 source manifest identity changed")
+    manifest = json.loads(source_manifest_bytes)
+    if (
+        manifest.get("profile") != "fp16-dit-dense-experimental"
+        or manifest.get("provenance", {}).get("converterRevision") != 7
+    ):
+        raise ValueError("OPT-0091 requires the authenticated revision-7 package")
+
+    tensors_by_shard: dict[str, list[tuple[str, dict[str, object]]]] = {}
+    for name, tensor in manifest["tensors"].items():
+        tensors_by_shard.setdefault(tensor["shard"], []).append((name, tensor))
+
+    dense_count = 0
+    source_dense_bytes = 0
+    packed_dense_bytes = 0
+    new_files: list[dict[str, object]] = []
+    output_root.mkdir(parents=True, exist_ok=True)
+    with tempfile.TemporaryDirectory(prefix=".opt-0091-", dir=output_root) as temporary:
+        stage = Path(temporary)
+        for file_record in manifest["files"]:
+            if file_record["kind"] != "weights":
+                new_files.append(dict(file_record))
+                continue
+            source_path = source / file_record["name"]
+            source_bytes = source_path.read_bytes()
+            if (
+                len(source_bytes) != file_record["byteLength"]
+                or _sha256(source_bytes) != file_record["sha256"]
+            ):
+                raise ValueError(f"source shard identity changed: {file_record['name']}")
+            output = bytearray()
+            tensors = sorted(
+                tensors_by_shard[file_record["name"]],
+                key=lambda item: item[1]["byteOffset"],
+            )
+            for name, tensor in tensors:
+                output.extend(b"\0" * (-len(output) % 256))
+                start = tensor["byteOffset"]
+                payload = source_bytes[start : start + tensor["byteLength"]]
+                tensor["byteOffset"] = len(output)
+                if tensor["layout"] == SOURCE_LAYOUT:
+                    if (
+                        tensor["dtype"] != "float16"
+                        or tensor["transformation"] != SOURCE_TRANSFORMATION
+                    ):
+                        raise ValueError(f"dense source contract changed: {name}")
+                    source_dense_bytes += len(payload)
+                    payload, storage_shape = pack_dense_tensor(
+                        payload, tensor["logicalShape"]
+                    )
+                    tensor.update(
+                        dtype=PACKED_DTYPE,
+                        layout=PACKED_LAYOUT,
+                        transformation=PACKED_TRANSFORMATION,
+                        storageShape=storage_shape,
+                        byteLength=len(payload),
+                    )
+                    dense_count += 1
+                    packed_dense_bytes += len(payload)
+                output.extend(payload)
+            output.extend(b"\0" * (-len(output) % 256))
+            destination = stage / file_record["name"]
+            destination.parent.mkdir(parents=True, exist_ok=True)
+            destination.write_bytes(output)
+            new_files.append(
+                {
+                    **file_record,
+                    "byteLength": len(output),
+                    "sha256": _sha256(output),
+                }
+            )
+
+        weight_bytes = sum(
+            record["byteLength"] for record in new_files if record["kind"] == "weights"
+        )
+        if dense_count != EXPECTED_DENSE_TENSORS or weight_bytes != EXPECTED_WEIGHT_BYTES:
+            raise ValueError("OPT-0091 packed inventory changed")
+        manifest["profile"] = "int8-dit-dense-experimental"
+        manifest["files"] = new_files
+        manifest["provenance"]["converterRevision"] = 9
+        manifest_bytes = _canonical_json(manifest)
+        manifest_sha256 = _sha256(manifest_bytes)
+        (stage / "manifest.json").write_bytes(manifest_bytes)
+        destination = output_root / manifest_sha256
+        if destination.is_symlink():
+            raise ValueError("OPT-0091 output must not be a symlink")
+        if destination.exists():
+            if (destination / "manifest.json").read_bytes() != manifest_bytes:
+                raise ValueError("existing OPT-0091 output does not match its digest")
+            _verify_runtime_files(destination, manifest)
+        else:
+            os.rename(stage, destination)
+            _verify_runtime_files(destination, manifest)
+
+    metrics: dict[str, int | str] = {
+        "manifestSha256": manifest_sha256,
+        "manifestBytes": len(manifest_bytes),
+        "denseTensorCount": dense_count,
+        "sourceDenseBytes": source_dense_bytes,
+        "packedDenseBytes": packed_dense_bytes,
+        "weightBytes": weight_bytes,
+    }
+    return destination, metrics
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("source", type=Path)
+    parser.add_argument("output_root", type=Path)
+    args = parser.parse_args()
+    destination, metrics = repack(args.source.resolve(), args.output_root.resolve())
+    print(json.dumps({**metrics, "directory": str(destination)}, indent=2))
+
+
+if __name__ == "__main__":
+    main()
diff --git a/packages/acestep/model/tests/test_repack_dit_int8.py b/packages/acestep/model/tests/test_repack_dit_int8.py
new file mode 100644
index 0000000..86c81cb
--- /dev/null
+++ b/packages/acestep/model/tests/test_repack_dit_int8.py
@@ -0,0 +1,40 @@
+import unittest
+import sys
+from pathlib import Path
+
+import numpy as np
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[1]))
+
+from repack_dit_int8 import PACKED_WORDS_PER_TILE, pack_dense_tensor
+
+
+class RepackDitInt8Test(unittest.TestCase):
+    def test_packs_one_n256_k32_tile_with_fp16_scales(self) -> None:
+        source = np.arange(32 * 256, dtype=np.float32).reshape(32, 256)
+        source = ((source % 255) - 127).astype("<f2")
+
+        payload, shape = pack_dense_tensor(source.tobytes(), [256, 32])
+
+        self.assertEqual(shape, [1, 1, PACKED_WORDS_PER_TILE])
+        self.assertEqual(len(payload), 8_704)
+        quantized = np.frombuffer(payload[:8_192], dtype=np.int8).reshape(32, 256)
+        scales = np.frombuffer(payload[8_192:], dtype="<f2")
+        expected_scales = (
+            np.max(np.abs(source.astype(np.float32)), axis=0) / np.float32(127)
+        ).astype("<f2")
+        np.testing.assert_array_equal(scales, expected_scales)
+        expected_quantized = np.clip(
+            np.rint(source.astype(np.float32) / expected_scales.astype(np.float32)),
+            -127,
+            127,
+        ).astype(np.int8)
+        np.testing.assert_array_equal(quantized, expected_quantized)
+
+    def test_rejects_non_native_shape(self) -> None:
+        with self.assertRaisesRegex(ValueError, "N256/K32"):
+            pack_dense_tensor(bytes(255 * 32 * 2), [255, 32])
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/packages/acestep/optimization/LEDGER.md b/packages/acestep/optimization/LEDGER.md
index 6af690c..17b1517 100644
--- a/packages/acestep/optimization/LEDGER.md
+++ b/packages/acestep/optimization/LEDGER.md
@@ -97,7 +97,7 @@ Next available ID: `OPT-0092`.
 | OPT-0088 | Portable device support | Every subgroup-dependent production owner (OPT-0032/0037 dense K4, OPT-0051 K7 row-reuse, OPT-0048 ConvTranspose K4, attention query8/quad-query) can gain a workgroup-memory counterpart consuming the unchanged hosted packages, selected by the existing execution-profile machinery, so adapters without `subgroups` (Safari, Firefox, iOS) run the production graph instead of failing `FEATURE_UNAVAILABLE`; compatibility experiment, bounded slowdown expected and reported, `shader-f16` stays fail-closed | pending | pending-integration | Portable dense/K7/ConvTranspose owners landed with test-enforced bit-identical arithmetic (byte-equal WGSL arithmetic sections, re-exported rev7/rev8 index math); attention routes to the existing portable oracle (reordered-rounding vs subgroup reduction). End-to-end masked-subgroups waveform and timing gates pending | [record](experiments/OPT-0088-portable-no-subgroup-production-path.md) | kernels c272b2d/c48c050/373e90a; selection wiring pending |
 | OPT-0089 | DiT weight quantization | Weight-only symmetric int8 (per-32-K-block fp16 scales, round-to-nearest, clamp ±127) fake-quantization of all 264 rev7 DiT GEMM tensors, dequantized in place and run through the completely unchanged production graph, preserves end-to-end 30 s waveform quality within a small numerical envelope, so an int8-resident DiT (~1.51 GB + scales) is a credible answer to the observed iPhone 17 Safari OOM kill at `1,789,925,376 / 3,020,808,192` uploaded bytes (layer 14/24); pure quantization-damage gate, zero kernel changes, distinct mechanism from abandoned OPT-0058 activation-quantized DP4a | positive | benchmark-only | Per-tensor damage uniform and small: NRMSE `0.00515–0.00634` (median `0.00559`), min SNR `43.96 dB`, no outlier tensor/family, so no fp16-retention map needed. Determinism gate reproduced the pinned fp16 baseline WAV byte-exactly, then fake-quant vs fp16 on identical seeds gave lo-fi/12345 waveform NRMSE `0.0669` (Pearson `0.99777`, LSD ≈`3.5 dB`, RMS Δ `−0.050 dB`) and latin/424242 NRMSE `0.2268` (Pearson `0.97460`, LSD ≈`4.7 dB`, RMS Δ `+0.089 dB`; per-second max `5.19` is a near-silent-ending small-denominator artifact) — trajectory divergence of the 8-evaluation sampler, not noise-like corruption; zero non-finite samples and exact peak parity. Projected int8 DiT phase peak ≈`1.862 GB` tracked GPU (`1.51 GB` int8 + `94 MB` scales + fp16 norms/shared + measured `127 MB` overhead) versus the observed iPhone 17 kill at ≈`1.920 GB` — plausibly fits, marginal ≈`58 MB` margin; int8 kernel work justified, listening gate mandatory before any product claim | [record](experiments/OPT-0089-dit-int8-weight-fake-quant-gate.md), [quant result](results/OPT-0089/quant-error.json), [waveform result](results/OPT-0089/waveform-metrics.json) | `scripts/requantize-dit-int8.py` (repo root); fake-quant package `ef8355b9…` (models-local, not hosted); benchmark-only, no kernel or production change |
 | OPT-0090 | DiT quantization listening preview | The authenticated OPT-0089 fake-quant package can be exposed as an explicit opt-in listening comparison without changing the production default, weakening package identity checks, or claiming packed-int8 size/runtime benefits | positive | integrated | Reproduced the recorded `ef8355b9…` package and byte-identical quant report, published the immutable full-size artifact, then added an Advanced listening selector with orderly model switching and explicit size/non-production disclosure. 43 web integration, 4 unit, and 2,029 ACE tests plus typecheck, formatting, production build, and all PR checks passed; fresh browser/GPU listening remains external | [record](experiments/OPT-0090-int8-quality-preview.md) | implementation `2816d6b83185cbde5abd6780a9f5ac903a655154`; artifact `ac50b5c854fb044ce058acb91d4cd9ab82d99cfa` |
-| OPT-0091 | Packed weight-only INT8 DiT runtime | Keep the 216 repeated-layer dense matrices as signed INT8 with per-output/K32 FP16 scales and dequantize inside subgroup and portable kernels, preserving the current activation rounding and increasing-K FP32 accumulation while materially reducing the 3.02 GB DiT package | pending | benchmark-only | Registered before implementation; converter, package, primitive, graph, browser, listening, and deployment gates remain open. This does not reuse OPT-0058 dynamic activation quantization | [record](experiments/OPT-0091-packed-int8-dit-runtime.md) | allocation `083c68ca7ad9031c41ec4a9faa9a1561d190f63e`; no implementation yet |
+| OPT-0091 | Packed weight-only INT8 DiT runtime | Keep the 216 repeated-layer dense matrices as signed INT8 with per-output/K32 FP16 scales and dequantize inside subgroup and portable kernels, preserving the current activation rounding and increasing-K FP32 accumulation while materially reducing the 3.02 GB DiT package | pending | experimental-preview | Deterministic packed package is 1.70 GB (43.7% smaller); manifest, hosted identity, automated tests, and build passed. Actual Chrome/WebGPU, waveform, and listening gates remain external, so production stays default and no quality/mobile claim is made | [record](experiments/OPT-0091-packed-int8-dit-runtime.md) | artifact `a3233c9f…`; HF `bc43ba20409825c13d7ef25694d39ac47dd8c9a4` |
 
 Experiment IDs are allocated before code changes, never reused, and never
 removed from this table.
diff --git a/packages/acestep/optimization/experiments/OPT-0091-packed-int8-dit-runtime.md b/packages/acestep/optimization/experiments/OPT-0091-packed-int8-dit-runtime.md
index a1d6dd3..f371db7 100644
--- a/packages/acestep/optimization/experiments/OPT-0091-packed-int8-dit-runtime.md
+++ b/packages/acestep/optimization/experiments/OPT-0091-packed-int8-dit-runtime.md
@@ -67,6 +67,17 @@ dynamic activation quantization or DP4A contraction.
 
 ## Current result
 
-Registered before implementation. No compressed package, kernel, browser run,
-quality approval, download reduction, mobile-support, or production claim is
-made yet.
+The deterministic repacker produced manifest `a3233c9f…` twice with identical
+files. The 216 packed dense tensors use 1,497,366,528 bytes; the complete DiT
+layer package is 1,699,602,432 bytes, down 43.7% from 3,020,808,192. The cold
+demo model set is 4.43 GB instead of 5.75 GB.
+
+The manifest passed the 456-tensor runtime contract, the hosted manifest and
+CORS identity were rechecked, and 2,032 ACE tests, 45 web integration tests,
+73 converter tests, typecheck, and the production build passed. The package is
+published in Hugging Face commit `bc43ba20409825c13d7ef25694d39ac47dd8c9a4`.
+
+The connected Chrome/WebGPU surface was unavailable, so the executable GPU,
+waveform, and listening gates remain external. This stays an opt-in
+experimental preview; production remains the default and no quality or mobile
+support claim is made.
diff --git a/packages/acestep/optimization/results/OPT-0091/result.json b/packages/acestep/optimization/results/OPT-0091/result.json
new file mode 100644
index 0000000..31d3bb9
--- /dev/null
+++ b/packages/acestep/optimization/results/OPT-0091/result.json
@@ -0,0 +1,31 @@
+{
+  "experiment": "OPT-0091",
+  "status": "pending-external-browser-validation",
+  "artifact": {
+    "manifestSha256": "a3233c9f97bc151b5ffa2a6cd8c9ecaee4e555497ee6fda20b70becaf7d55da1",
+    "manifestBytes": 262613,
+    "denseTensorCount": 216,
+    "packedDenseBytes": 1497366528,
+    "weightBytes": 1699602432,
+    "sourceWeightBytes": 3020808192,
+    "reductionPercent": 43.73683054418835,
+    "coldModelSetBytes": 4426524415,
+    "huggingFaceCommit": "bc43ba20409825c13d7ef25694d39ac47dd8c9a4"
+  },
+  "automatedValidation": {
+    "deterministicReproductions": 2,
+    "identicalGeneratedFiles": 49,
+    "aceTestsPassed": 2032,
+    "webIntegrationTestsPassed": 45,
+    "converterTestsPassed": 73,
+    "typecheckPassed": true,
+    "productionBuildPassed": true,
+    "hostedManifestVerified": true,
+    "githubPagesCorsVerified": true
+  },
+  "externalGates": {
+    "chromeWebGpu": "pending",
+    "waveform": "pending",
+    "listening": "pending"
+  }
+}
diff --git a/packages/acestep/src/model/manifest.ts b/packages/acestep/src/model/manifest.ts
index afb0ac4..bb547f9 100644
--- a/packages/acestep/src/model/manifest.ts
+++ b/packages/acestep/src/model/manifest.ts
@@ -12,6 +12,7 @@ export const ACE_PACKAGE_CONVERTER_REVISION = 4;
 export const ACE_EXPERIMENTAL_VAE_PACKAGE_CONVERTER_REVISION = 6;
 export const ACE_OPT_0054_EXPERIMENTAL_VAE_PACKAGE_CONVERTER_REVISION = 7;
 export const ACE_EXPERIMENTAL_DIT_DENSE_PACKAGE_CONVERTER_REVISION = 8;
+export const ACE_PACKED_INT8_DIT_PACKAGE_CONVERTER_REVISION = 9;
 export const ACE_EXPERIMENTAL_DIT_DENSE_PARAMETER_ELEMENTS = 1_510_404_096;
 export const ACE_EXPERIMENTAL_DIT_DENSE_PARAMETER_BYTES = 3_020_808_192;
 export const ACE_EXPERIMENTAL_DIT_DENSE_LOGICAL_TENSOR_COUNT = 456;
@@ -31,6 +32,10 @@ export const ACE_DIT_DENSE_FP16_TILE_LAYOUT =
   "dit-gemm-n256-k32-tile-major-v1" as const;
 export const ACE_DIT_DENSE_FP16_TRANSFORMATION =
   "bf16-to-ieee-fp16-dit-gemm-n256-k32-tile-major-v1" as const;
+export const ACE_DIT_DENSE_INT8_TILE_LAYOUT =
+  "dit-gemm-n256-k32-int8-fp16-scale-tile-major-v1" as const;
+export const ACE_DIT_DENSE_INT8_TRANSFORMATION =
+  "bf16-to-symmetric-int8-fp16-scale-n256-k32-tile-major-v1" as const;
 export const ACE_DIT_DENSE_K4_FP16_LAYOUT =
   "dit-gemm-n128-k4-output4-lane32-k4-v1" as const;
 export const ACE_DIT_DENSE_K4_FP16_TRANSFORMATION =
@@ -105,7 +110,8 @@ export type AcePackageProfile =
   | "reference"
   | "fp16"
   | "fp16-vae-experimental"
-  | "fp16-dit-dense-experimental";
+  | "fp16-dit-dense-experimental"
+  | "int8-dit-dense-experimental";
 export type AcePackageFileKind =
   | "conversion-plan"
   | "upstream-asset"
@@ -116,7 +122,8 @@ export type AceTensorDtype =
   | "float16"
   | "float32"
   | "uint32"
-  | "uint32-bf16-pairs";
+  | "uint32-bf16-pairs"
+  | "uint32-int8-fp16-blocks";
 export type AceTensorPhase =
   | "planner"
   | "text"
@@ -134,6 +141,7 @@ export type AceTensorLayout =
   | "contiguous-nct-f32"
   | typeof ACE_DIT_GEMM_TILE_LAYOUT
   | typeof ACE_DIT_DENSE_FP16_TILE_LAYOUT
+  | typeof ACE_DIT_DENSE_INT8_TILE_LAYOUT
   | typeof ACE_DIT_DENSE_K4_FP16_LAYOUT
   | typeof ACE_VAE_CONV1D_LAYOUT
   | typeof ACE_VAE_CONV_TRANSPOSE1D_LAYOUT
@@ -152,6 +160,7 @@ export type AceTensorTransformation =
   | typeof ACE_DIT_GEMM_PACKED_BF16_TRANSFORMATION
   | typeof ACE_DIT_GEMM_FP16_TRANSFORMATION
   | typeof ACE_DIT_DENSE_FP16_TRANSFORMATION
+  | typeof ACE_DIT_DENSE_INT8_TRANSFORMATION
   | typeof ACE_DIT_DENSE_K4_FP16_TRANSFORMATION
   | typeof ACE_VAE_CONV1D_TRANSFORMATION
   | typeof ACE_VAE_CONV_TRANSPOSE1D_TRANSFORMATION
@@ -335,6 +344,7 @@ const DTYPE_BYTES: Readonly<Record<AceTensorDtype, number>> = {
   float32: 4,
   uint32: 4,
   "uint32-bf16-pairs": 4,
+  "uint32-int8-fp16-blocks": 4,
 };
 const TENSOR_PHASES = new Set<AceTensorPhase>([
   "planner",
@@ -355,6 +365,7 @@ const TENSOR_TRANSFORMATIONS = new Set([
   "bf16-to-fp32",
   ACE_DIT_GEMM_PACKED_BF16_TRANSFORMATION,
   ACE_DIT_GEMM_FP16_TRANSFORMATION,
+  ACE_DIT_DENSE_INT8_TRANSFORMATION,
   ACE_DIT_DENSE_K4_FP16_TRANSFORMATION,
   ACE_VAE_CONV1D_TRANSFORMATION,
   ACE_VAE_CONV_TRANSPOSE1D_TRANSFORMATION,
@@ -375,6 +386,7 @@ const NATIVE_LAYOUT_BY_TRANSFORMATION: Readonly<
   [ACE_DIT_GEMM_PACKED_BF16_TRANSFORMATION]: ACE_DIT_GEMM_TILE_LAYOUT,
   [ACE_DIT_GEMM_FP16_TRANSFORMATION]: ACE_DIT_GEMM_TILE_LAYOUT,
   [ACE_DIT_DENSE_FP16_TRANSFORMATION]: ACE_DIT_DENSE_FP16_TILE_LAYOUT,
+  [ACE_DIT_DENSE_INT8_TRANSFORMATION]: ACE_DIT_DENSE_INT8_TILE_LAYOUT,
   [ACE_DIT_DENSE_K4_FP16_TRANSFORMATION]: ACE_DIT_DENSE_K4_FP16_LAYOUT,
   [ACE_VAE_CONV1D_TRANSFORMATION]: ACE_VAE_CONV1D_LAYOUT,
   [ACE_VAE_CONV_TRANSPOSE1D_TRANSFORMATION]: ACE_VAE_CONV_TRANSPOSE1D_LAYOUT,
@@ -519,7 +531,8 @@ export function parseAcePackageManifest(
     root.profile !== "reference" &&
     root.profile !== "fp16" &&
     root.profile !== "fp16-vae-experimental" &&
-    root.profile !== "fp16-dit-dense-experimental"
+    root.profile !== "fp16-dit-dense-experimental" &&
+    root.profile !== "int8-dit-dense-experimental"
   ) {
     fail("unknown package profile");
   }
@@ -570,7 +583,10 @@ export function parseAcePackageManifest(
   if (root.profile === "fp16-vae-experimental") {
     validateExperimentalVaePayload(tensors, provenance.converterRevision);
   }
-  if (root.profile === "fp16-dit-dense-experimental") {
+  if (
+    root.profile === "fp16-dit-dense-experimental" ||
+    root.profile === "int8-dit-dense-experimental"
+  ) {
     validateExperimentalDitDensePayload(tensors, provenance.converterRevision);
   }
 
@@ -865,6 +881,8 @@ function parseProvenance(
     : profile === "fp16-dit-dense-experimental"
       ? authenticatedDitDenseConverterRevision ??
         ACE_EXPERIMENTAL_DIT_DENSE_PACKAGE_CONVERTER_REVISION
+      : profile === "int8-dit-dense-experimental"
+        ? ACE_PACKED_INT8_DIT_PACKAGE_CONVERTER_REVISION
       : ACE_PACKAGE_CONVERTER_REVISION;
   if (raw.converterRevision !== converterRevision) {
     fail("unsupported converter revision");
@@ -1030,6 +1048,7 @@ function parseTensors(
       (transformation === ACE_DIT_GEMM_PACKED_BF16_TRANSFORMATION ||
         transformation === ACE_DIT_GEMM_FP16_TRANSFORMATION ||
         transformation === ACE_DIT_DENSE_FP16_TRANSFORMATION ||
+        transformation === ACE_DIT_DENSE_INT8_TRANSFORMATION ||
         transformation === ACE_DIT_DENSE_K4_FP16_TRANSFORMATION ||
         transformation === ACE_VAE_K1_FP16_TILE_TRANSFORMATION ||
         transformation ===
@@ -1042,7 +1061,13 @@ function parseTensors(
     }
     const layoutBase = rowSharded ? "row-shard-axis0" : "source-row-major";
     let expectedStorageShape: number[];
-    if (transformation === ACE_DIT_DENSE_K4_FP16_TRANSFORMATION) {
+    if (transformation === ACE_DIT_DENSE_INT8_TRANSFORMATION) {
+      const [columns, inner] = logicalShape;
+      if (columns! % 256 !== 0 || inner! % 32 !== 0) {
+        fail(`${path} has an invalid packed INT8 DiT shape`);
+      }
+      expectedStorageShape = [columns! / 256, inner! / 32, 2_176];
+    } else if (transformation === ACE_DIT_DENSE_K4_FP16_TRANSFORMATION) {
       const [columns, inner] = logicalShape;
       if (columns! % 128 !== 0 || inner! % 4 !== 0) {
         fail(`${path} has an invalid packed DiT K4 shape`);
@@ -1461,33 +1486,47 @@ function validateExperimentalDitDensePayload(
   let parameterElements = 0;
   let parameterBytes = 0;
   const authenticatedRev7 = converterRevision === 7;
+  const packedInt8 =
+    converterRevision === ACE_PACKED_INT8_DIT_PACKAGE_CONVERTER_REVISION;
   for (const [name, tensor] of ditTensors) {
     const commonValid = tensor.logicalTensor === name &&
       tensor.partStart === 0 &&
       tensor.partEnd === tensor.logicalShape[0];
     const valid = denseNames.has(name)
       ? commonValid &&
-        tensor.dtype === "float16" &&
         tensor.logicalShape.length === 2 &&
-        (authenticatedRev7
-          ? tensor.layout === ACE_DIT_DENSE_FP16_TILE_LAYOUT &&
-            tensor.transformation === ACE_DIT_DENSE_FP16_TRANSFORMATION &&
+        (packedInt8
+          ? tensor.dtype === "uint32-int8-fp16-blocks" &&
+            tensor.layout === ACE_DIT_DENSE_INT8_TILE_LAYOUT &&
+            tensor.transformation === ACE_DIT_DENSE_INT8_TRANSFORMATION &&
             tensor.logicalShape[0]! % 256 === 0 &&
             tensor.logicalShape[1]! % 32 === 0 &&
-            arraysEqual(tensor.storageShape, tensor.logicalShape)
-          : converterRevision ===
-              ACE_EXPERIMENTAL_DIT_DENSE_PACKAGE_CONVERTER_REVISION &&
-            tensor.layout === ACE_DIT_DENSE_K4_FP16_LAYOUT &&
-            tensor.transformation === ACE_DIT_DENSE_K4_FP16_TRANSFORMATION &&
-            tensor.logicalShape[0]! % 128 === 0 &&
-            tensor.logicalShape[1]! % 4 === 0 &&
             arraysEqual(tensor.storageShape, [
-              tensor.logicalShape[0]! / 128,
-              tensor.logicalShape[1]! / 4,
-              4,
-              32,
-              4,
-            ]))
+              tensor.logicalShape[0]! / 256,
+              tensor.logicalShape[1]! / 32,
+              2_176,
+            ])
+          : tensor.dtype === "float16" &&
+            (authenticatedRev7
+              ? tensor.layout === ACE_DIT_DENSE_FP16_TILE_LAYOUT &&
+                tensor.transformation === ACE_DIT_DENSE_FP16_TRANSFORMATION &&
+                tensor.logicalShape[0]! % 256 === 0 &&
+                tensor.logicalShape[1]! % 32 === 0 &&
+                arraysEqual(tensor.storageShape, tensor.logicalShape)
+              : converterRevision ===
+                  ACE_EXPERIMENTAL_DIT_DENSE_PACKAGE_CONVERTER_REVISION &&
+                tensor.layout === ACE_DIT_DENSE_K4_FP16_LAYOUT &&
+                tensor.transformation ===
+                  ACE_DIT_DENSE_K4_FP16_TRANSFORMATION &&
+                tensor.logicalShape[0]! % 128 === 0 &&
+                tensor.logicalShape[1]! % 4 === 0 &&
+                arraysEqual(tensor.storageShape, [
+                  tensor.logicalShape[0]! / 128,
+                  tensor.logicalShape[1]! / 4,
+                  4,
+                  32,
+                  4,
+                ])))
       : crossCacheNames.has(name)
         ? commonValid &&
           tensor.dtype === "uint32-bf16-pairs" &&
@@ -1511,7 +1550,9 @@ function validateExperimentalDitDensePayload(
   }
   if (
     parameterElements !== ACE_EXPERIMENTAL_DIT_DENSE_PARAMETER_ELEMENTS ||
-    parameterBytes !== ACE_EXPERIMENTAL_DIT_DENSE_PARAMETER_BYTES
+    parameterBytes !== (packedInt8
+      ? 1_699_602_432
+      : ACE_EXPERIMENTAL_DIT_DENSE_PARAMETER_BYTES)
   ) {
     fail(
       "experimental mixed DiT layer payload does not match its exact " +
@@ -1530,11 +1571,13 @@ function validateStoragePolicy(
   const valid =
     (transformation === "preserve-bf16-bits-pack-u32-pairs" &&
       (profile === "reference" ||
-        profile === "fp16-dit-dense-experimental") &&
+        profile === "fp16-dit-dense-experimental" ||
+        profile === "int8-dit-dense-experimental") &&
       dtype === "uint32-bf16-pairs") ||
     (transformation === ACE_DIT_GEMM_PACKED_BF16_TRANSFORMATION &&
       (profile === "reference" ||
-        profile === "fp16-dit-dense-experimental") &&
+        profile === "fp16-dit-dense-experimental" ||
+        profile === "int8-dit-dense-experimental") &&
       dtype === "uint32-bf16-pairs") ||
     (transformation === "bf16-to-ieee-fp16" &&
       (profile === "fp16" || profile === "fp16-vae-experimental") &&
@@ -1551,6 +1594,10 @@ function validateStoragePolicy(
       profile === "fp16-dit-dense-experimental" &&
       converterRevision === 7 &&
       dtype === "float16") ||
+    (transformation === ACE_DIT_DENSE_INT8_TRANSFORMATION &&
+      profile === "int8-dit-dense-experimental" &&
+      converterRevision === ACE_PACKED_INT8_DIT_PACKAGE_CONVERTER_REVISION &&
+      dtype === "uint32-int8-fp16-blocks") ||
     ((transformation === "bf16-to-fp32" ||
       transformation === ACE_VAE_CONV1D_TRANSFORMATION ||
       transformation === ACE_VAE_CONV_TRANSPOSE1D_TRANSFORMATION ||
@@ -1589,7 +1636,8 @@ function validateNativeTensorContract(
     transformation === ACE_DIT_GEMM_FP16_TRANSFORMATION;
   const ditDenseFp16Transformation =
     transformation === ACE_DIT_DENSE_FP16_TRANSFORMATION ||
-    transformation === ACE_DIT_DENSE_K4_FP16_TRANSFORMATION;
+    transformation === ACE_DIT_DENSE_K4_FP16_TRANSFORMATION ||
+    transformation === ACE_DIT_DENSE_INT8_TRANSFORMATION;
   const ditGemmSource = DIT_GEMM_SOURCE.test(source);
   const ditDenseFp16Source = DIT_REPEATED_DENSE_SOURCE.test(source);
   const conv1dTransformation =
@@ -1621,7 +1669,10 @@ function validateNativeTensorContract(
       phase !== "dit" ||
       logicalShape.length !== 2 ||
       logicalShape[0]! %
-        (transformation === ACE_DIT_DENSE_FP16_TRANSFORMATION ? 256 : 128) !==
+        (transformation === ACE_DIT_DENSE_FP16_TRANSFORMATION ||
+            transformation === ACE_DIT_DENSE_INT8_TRANSFORMATION
+          ? 256
+          : 128) !==
         0 ||
       logicalShape[1]! %
         (transformation === ACE_DIT_DENSE_K4_FP16_TRANSFORMATION ? 4 : 32) !==
diff --git a/packages/acestep/src/runtime/diagnostics.ts b/packages/acestep/src/runtime/diagnostics.ts
index 36378d7..e48e7d7 100644
--- a/packages/acestep/src/runtime/diagnostics.ts
+++ b/packages/acestep/src/runtime/diagnostics.ts
@@ -40,16 +40,19 @@ export interface AceRuntimeDiagnostics {
   readonly ditDenseManifestId: string;
   readonly ditDenseManifestUrl: string;
   readonly ditDenseManifestSha256: string;
-  readonly ditDenseManifestByteLength: 254_357 | 257_789;
+  readonly ditDenseManifestByteLength: 254_357 | 257_789 | 262_613;
   readonly ditDenseRuntimeProfile:
     | "opt-0009-fp16-fp32-dense-v1"
+    | "opt-0091-int8-weight-only-v1"
     | "opt-0037-k4-fp16-partials-v1"
     | "opt-0056-selective-k4-exact-down-v1";
   readonly ditDenseKernelSetId:
     | "opt-0009-n256-k32-fp16-fp32-v1"
     | "opt-0037-opt-0032-k4-partials-fixed32-v1"
     | "opt-0056-opt0032-k4-plus-exact-down-fixed32-v1"
-    | "opt-0088-dense-fp16-fp32-portable-v1";
+    | "opt-0088-dense-fp16-fp32-portable-v1"
+    | "opt-0091-int8-weight-only-fixed32-v1"
+    | "opt-0091-int8-weight-only-portable-v1";
   /** Present for the explicit diagnostic or exact production quad profile. */
   readonly ditAttentionRuntimeProfile?:
     | "opt-0062-fixed32-quad-query32-full-self-v1"
@@ -58,8 +61,8 @@ export interface AceRuntimeDiagnostics {
     | "opt-0062-query8-plus-quad-query32-full-self-v1"
     | "opt-0070-opt0062-query8-plus-quad-query32-full-self-production-v1"
     | "opt-0088-portable-attention-oracle-v1";
-  readonly ditDenseLayerBytes: 3_020_808_192;
-  readonly ditResidentWeightBytes: 3_150_917_888;
+  readonly ditDenseLayerBytes: 3_020_808_192 | 1_699_602_432;
+  readonly ditResidentWeightBytes: 3_150_917_888 | 1_829_712_128;
   readonly vaeManifestId: string;
   readonly vaeManifestUrl: string;
   readonly vaeManifestSha256: string;
diff --git a/packages/acestep/src/runtime/protocol.ts b/packages/acestep/src/runtime/protocol.ts
index 0e51b93..aefa198 100644
--- a/packages/acestep/src/runtime/protocol.ts
+++ b/packages/acestep/src/runtime/protocol.ts
@@ -43,6 +43,13 @@ import {
   ACE_OPT_0056_DIT_SELECTIVE_K4_RUNTIME_PROFILE,
   ACE_OPT_0088_DIT_DENSE_PORTABLE_KERNEL_SET_ID,
   ACE_OPT_0089_DIT_FAKE_QUANT_MANIFEST_SHA256,
+  ACE_OPT_0091_DIT_INT8_KERNEL_SET_ID,
+  ACE_OPT_0091_DIT_INT8_LAYER_BYTES,
+  ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES,
+  ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256,
+  ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID,
+  ACE_OPT_0091_DIT_INT8_RESIDENT_WEIGHT_BYTES,
+  ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
 } from "../webgpu/dit-fp16-package.js";
 import {
   ACE_OPT_0062_DIT_QUAD_QUERY_ATTENTION_KERNEL_SET_ID,
@@ -135,6 +142,11 @@ export type AceWorkerVaePackageConfiguration =
     }>;
 
 export type AceWorkerDitDensePackageConfiguration =
+  | Readonly<{
+      readonly manifestUrl: string;
+      readonly manifestSha256: typeof ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256;
+      readonly runtimeProfile: typeof ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE;
+    }>
   | Readonly<{
       readonly manifestUrl: string;
       readonly manifestSha256: typeof ACE_OPT_0009_DIT_DENSE_MANIFEST_SHA256;
@@ -482,8 +494,10 @@ function isWorkerConfiguration(value: unknown): value is AceWorkerConfiguration
           ACE_OPT_0062_DIT_QUAD_QUERY_ATTENTION_RUNTIME_PROFILE ||
         value.ditAttentionRuntimeProfile ===
           ACE_OPT_0070_DIT_QUAD_QUERY_ATTENTION_RUNTIME_PROFILE) &&
-        value.ditDensePackage.runtimeProfile ===
-          ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE)) &&
+        (value.ditDensePackage.runtimeProfile ===
+            ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE ||
+          value.ditDensePackage.runtimeProfile ===
+            ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE))) &&
     isWorkerVaePackageConfiguration(value.vaePackage) &&
     ((value.ditAttentionRuntimeProfile ===
         ACE_OPT_0070_DIT_QUAD_QUERY_ATTENTION_RUNTIME_PROFILE) ===
@@ -508,6 +522,8 @@ function isWorkerDitDensePackageConfiguration(
       (value.runtimeProfile === ACE_OPT_0037_DIT_K4_RUNTIME_PROFILE ||
         value.runtimeProfile ===
           ACE_OPT_0056_DIT_SELECTIVE_K4_RUNTIME_PROFILE)) ||
+      (value.manifestSha256 === ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256 &&
+        value.runtimeProfile === ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE) ||
       ((value.manifestSha256 === ACE_OPT_0009_DIT_DENSE_MANIFEST_SHA256 ||
         value.manifestSha256 ===
           ACE_OPT_0089_DIT_FAKE_QUANT_MANIFEST_SHA256) &&
@@ -685,8 +701,17 @@ export function isAceRuntimeDiagnosticsValue(
         ACE_OPT_0070_VAE_C2378_MAXIMUM_WINDOW_FRAMES)
   );
   const ditDenseIdentityValid = isRecord(value) && (
-    (value.ditDenseManifestSha256 ===
-        ACE_OPT_0009_DIT_DENSE_MANIFEST_SHA256 &&
+    (value.ditDenseManifestSha256 === ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256 &&
+      value.ditDenseManifestByteLength === ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES &&
+      value.ditDenseRuntimeProfile === ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE &&
+      (value.ditDenseKernelSetId === ACE_OPT_0091_DIT_INT8_KERNEL_SET_ID ||
+        value.ditDenseKernelSetId === ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID) &&
+      value.ditDenseLayerBytes === ACE_OPT_0091_DIT_INT8_LAYER_BYTES &&
+      value.ditResidentWeightBytes === ACE_OPT_0091_DIT_INT8_RESIDENT_WEIGHT_BYTES) ||
+    ((value.ditDenseManifestSha256 ===
+          ACE_OPT_0009_DIT_DENSE_MANIFEST_SHA256 ||
+        value.ditDenseManifestSha256 ===
+          ACE_OPT_0089_DIT_FAKE_QUANT_MANIFEST_SHA256) &&
       value.ditDenseManifestByteLength ===
         ACE_OPT_0009_DIT_DENSE_MANIFEST_BYTES &&
       value.ditDenseRuntimeProfile ===
@@ -753,8 +778,10 @@ export function isAceRuntimeDiagnosticsValue(
     value.executionProfile.id === ACE_REFERENCE_PORTABLE_PROFILE.id;
   const portableKernelIdentityCoherent = isRecord(value) && (
     portableExecutionProfile
-      ? value.ditDenseKernelSetId ===
-          ACE_OPT_0088_DIT_DENSE_PORTABLE_KERNEL_SET_ID &&
+      ? ((value.ditDenseRuntimeProfile === ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE &&
+            value.ditDenseKernelSetId === ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID) ||
+          (value.ditDenseRuntimeProfile === ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE &&
+            value.ditDenseKernelSetId === ACE_OPT_0088_DIT_DENSE_PORTABLE_KERNEL_SET_ID)) &&
         (value.ditAttentionKernelSetId === undefined ||
           value.ditAttentionKernelSetId ===
             ACE_OPT_0088_DIT_PORTABLE_ATTENTION_KERNEL_SET_ID) &&
@@ -762,6 +789,8 @@ export function isAceRuntimeDiagnosticsValue(
           ACE_OPT_0088_VAE_FP16_PORTABLE_DUAL_K4_PROFILE.kernelSetId
       : value.ditDenseKernelSetId !==
           ACE_OPT_0088_DIT_DENSE_PORTABLE_KERNEL_SET_ID &&
+        value.ditDenseKernelSetId !==
+          ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID &&
         value.ditAttentionKernelSetId !==
           ACE_OPT_0088_DIT_PORTABLE_ATTENTION_KERNEL_SET_ID &&
         value.vaeKernelSetId !==
@@ -810,7 +839,9 @@ export function isAceRuntimeDiagnosticsValue(
     !ditAttentionIdentityValid ||
     (value.ditAttentionRuntimeProfile !== undefined &&
       value.ditDenseRuntimeProfile !==
-        ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE) ||
+          ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE &&
+      value.ditDenseRuntimeProfile !==
+          ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE) ||
     !isNonEmptyString(value.vaeManifestId) ||
     !isNonEmptyString(value.vaeManifestUrl) ||
     !vaeIdentityValid ||
diff --git a/packages/acestep/src/runtime/webgpu-pipeline.ts b/packages/acestep/src/runtime/webgpu-pipeline.ts
index 7b7dcc8..76a6c5e 100644
--- a/packages/acestep/src/runtime/webgpu-pipeline.ts
+++ b/packages/acestep/src/runtime/webgpu-pipeline.ts
@@ -168,11 +168,21 @@ import {
   ACE_OPT_0088_DIT_DENSE_PORTABLE_KERNEL_SET_ID,
   ACE_OPT_0089_DIT_FAKE_QUANT_MANIFEST_BYTES,
   ACE_OPT_0089_DIT_FAKE_QUANT_MANIFEST_SHA256,
+  ACE_OPT_0091_DIT_INT8_CONVERTER_REVISION,
+  ACE_OPT_0091_DIT_INT8_KERNEL_SET_ID,
+  ACE_OPT_0091_DIT_INT8_LAYER_BYTES,
+  ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES,
+  ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256,
+  ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID,
+  ACE_OPT_0091_DIT_INT8_RESIDENT_WEIGHT_BYTES,
+  ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
+  ACE_OPT_0091_DIT_INT8_WEIGHT_FILES,
   createAceReferenceDitSharedManifestView,
   isAceReferenceDitLayerWeightFile,
   requireAceOpt0009DitDensePackageIdentity,
   requireAceOpt0037DitK4PackageIdentity,
   requireAceOpt0089DitFakeQuantPackageIdentity,
+  requireAceOpt0091DitInt8PackageIdentity,
 } from "../webgpu/dit-fp16-package.js";
 import {
   ACE_TURBO_EIGHT_SAMPLER_SCHEDULE_PROFILE,
@@ -3066,7 +3076,9 @@ export function createAceWebGpuPipelineBackend(
       return await loadAcePackageManifest({
         manifestUrl: configuration.manifestUrl,
         expectedManifestSha256: configuration.manifestSha256,
-        expectedProfile: "fp16-dit-dense-experimental",
+        expectedProfile: identity.role === "opt-0091-packed-int8-preview"
+          ? "int8-dit-dense-experimental"
+          : "fp16-dit-dense-experimental",
         ...(identity.role === "opt-0009-rev7-oracle" ||
             identity.role === "opt-0089-rev7-fake-quant-preview"
           ? { authenticatedDitDenseConverterRevision: 7 as const }
@@ -3093,6 +3105,9 @@ export function createAceWebGpuPipelineBackend(
           ? loaded.manifest.provenance.converterRevision ===
               ACE_OPT_0009_DIT_DENSE_CONVERTER_REVISION
             ? createAceOpt0009DitDenseAcquisitionManifest(loaded.manifest)
+            : loaded.manifest.provenance.converterRevision ===
+                ACE_OPT_0091_DIT_INT8_CONVERTER_REVISION
+              ? createAceOpt0091DitInt8AcquisitionManifest(loaded.manifest)
             : createAceOpt0037DitK4AcquisitionManifest(loaded.manifest)
           : createAceOpt0011VaeAcquisitionManifest(loaded.manifest);
       return await acquireAceModelFiles({
@@ -3240,6 +3255,35 @@ export function createAceOpt0009DitDenseAcquisitionManifest(
   return Object.freeze({ ...manifest, files });
 }
 
+/** @internal Resolve the exact 48 packed INT8 mixed-layer shards. */
+export function createAceOpt0091DitInt8AcquisitionManifest(
+  manifest: AcePackageManifest,
+): AcePackageManifest {
+  if (
+    manifest.profile !== "int8-dit-dense-experimental" ||
+    manifest.provenance.converterRevision !==
+      ACE_OPT_0091_DIT_INT8_CONVERTER_REVISION
+  ) {
+    throw new Error("OPT-0091 acquisition requires the revision-9 INT8 package");
+  }
+  const byName = new Map(manifest.files.map((file) => [file.name, file]));
+  const files = Object.freeze(ACE_OPT_0091_DIT_INT8_WEIGHT_FILES.map((name) => {
+    const file = byName.get(name);
+    if (file === undefined || file.kind !== "weights") {
+      throw new Error(`OPT-0091 authenticated manifest is missing ${name}`);
+    }
+    return file;
+  }));
+  if (
+    files.length !== 48 ||
+    files.reduce((sum, file) => sum + file.byteLength, 0) !==
+      ACE_OPT_0091_DIT_INT8_LAYER_BYTES
+  ) {
+    throw new Error("OPT-0091 acquisition physical layer inventory changed");
+  }
+  return Object.freeze({ ...manifest, files });
+}
+
 /** @internal Re-resolve the exact 48 physical rev8 K4 mixed-layer shards. */
 export function createAceOpt0037DitK4AcquisitionManifest(
   manifest: AcePackageManifest,
@@ -3390,6 +3434,18 @@ function tokenizeConditioning(
 }
 
 export type AceDitDensePackageRuntimeIdentity =
+  | Readonly<{
+      readonly role: "opt-0091-packed-int8-preview";
+      readonly manifestSha256: typeof ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256;
+      readonly manifestByteLength: typeof ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES;
+      readonly runtimeProfile: typeof ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE;
+      readonly kernelSetId:
+        | typeof ACE_OPT_0091_DIT_INT8_KERNEL_SET_ID
+        | typeof ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID;
+      readonly layerBytes: typeof ACE_OPT_0091_DIT_INT8_LAYER_BYTES;
+      readonly residentWeightBytes:
+        typeof ACE_OPT_0091_DIT_INT8_RESIDENT_WEIGHT_BYTES;
+    }>
   | Readonly<{
       readonly role: "opt-0009-rev7-oracle";
       readonly manifestSha256: typeof ACE_OPT_0009_DIT_DENSE_MANIFEST_SHA256;
@@ -3444,6 +3500,22 @@ export function resolveAceDitDensePackageRuntimeIdentity(
   configuration: AceWorkerDitDensePackageConfiguration,
   kernelBackend: AceKernelBackend = "subgroups",
 ): AceDitDensePackageRuntimeIdentity {
+  if (
+    configuration.manifestSha256 === ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256 &&
+    configuration.runtimeProfile === ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE
+  ) {
+    return Object.freeze({
+      role: "opt-0091-packed-int8-preview",
+      manifestSha256: ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256,
+      manifestByteLength: ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES,
+      runtimeProfile: ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
+      kernelSetId: kernelBackend === "portable"
+        ? ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID
+        : ACE_OPT_0091_DIT_INT8_KERNEL_SET_ID,
+      layerBytes: ACE_OPT_0091_DIT_INT8_LAYER_BYTES,
+      residentWeightBytes: ACE_OPT_0091_DIT_INT8_RESIDENT_WEIGHT_BYTES,
+    });
+  }
   if (
     configuration.manifestSha256 ===
       ACE_OPT_0089_DIT_FAKE_QUANT_MANIFEST_SHA256 &&
@@ -3784,13 +3856,17 @@ function requireLoadedDitDenseManifestIdentity(
     requireAceOpt0009DitDensePackageIdentity(loaded);
   } else if (identity.role === "opt-0089-rev7-fake-quant-preview") {
     requireAceOpt0089DitFakeQuantPackageIdentity(loaded);
+  } else if (identity.role === "opt-0091-packed-int8-preview") {
+    requireAceOpt0091DitInt8PackageIdentity(loaded);
   } else {
     requireAceOpt0037DitK4PackageIdentity(loaded);
   }
   if (
     loaded.manifestSha256 !== configuration.manifestSha256 ||
     loaded.manifestByteLength !== identity.manifestByteLength ||
-    loaded.manifest.profile !== "fp16-dit-dense-experimental"
+    loaded.manifest.profile !== (identity.role === "opt-0091-packed-int8-preview"
+      ? "int8-dit-dense-experimental"
+      : "fp16-dit-dense-experimental")
   ) {
     throw new Error(
       "Loaded mixed DiT manifest differs from its exact initialization trust root",
@@ -3833,7 +3909,9 @@ function requireProductionConfiguration(
         configuration.ditAttentionRuntimeProfile !==
           ACE_OPT_0070_DIT_QUAD_QUERY_ATTENTION_RUNTIME_PROFILE) ||
         configuration.ditDensePackage.runtimeProfile !==
-          ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE)) ||
+            ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE &&
+        configuration.ditDensePackage.runtimeProfile !==
+            ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE)) ||
     vaeIdentity === undefined ||
     vaeWindowIdentity === undefined ||
     ((configuration.ditAttentionRuntimeProfile ===
@@ -3897,9 +3975,12 @@ function requireDitDenseAcquisition(
   identity: AceDitDensePackageRuntimeIdentity,
 ): void {
   const names = [...acquired.files.keys()];
-  const expectedFiles = identity.role === "opt-0009-rev7-oracle"
-    ? ACE_OPT_0009_DIT_DENSE_WEIGHT_FILES
-    : ACE_OPT_0037_DIT_K4_WEIGHT_FILES;
+  const expectedFiles = identity.role === "opt-0091-packed-int8-preview"
+    ? ACE_OPT_0091_DIT_INT8_WEIGHT_FILES
+    : identity.role === "opt-0009-rev7-oracle" ||
+        identity.role === "opt-0089-rev7-fake-quant-preview"
+      ? ACE_OPT_0009_DIT_DENSE_WEIGHT_FILES
+      : ACE_OPT_0037_DIT_K4_WEIGHT_FILES;
   if (
     acquired.files.size !== expectedFiles.length ||
     acquired.plan.files.length !== expectedFiles.length ||
diff --git a/packages/acestep/src/webgpu/ace-dit-package.ts b/packages/acestep/src/webgpu/ace-dit-package.ts
index c2e2662..623f991 100644
--- a/packages/acestep/src/webgpu/ace-dit-package.ts
+++ b/packages/acestep/src/webgpu/ace-dit-package.ts
@@ -4,6 +4,8 @@ import type { AceGpuLogicalTensor } from "../model/gpu-tensors.js";
 import {
   ACE_DIT_DENSE_K4_FP16_LAYOUT,
   ACE_DIT_DENSE_K4_FP16_TRANSFORMATION,
+  ACE_DIT_DENSE_INT8_TILE_LAYOUT,
+  ACE_DIT_DENSE_INT8_TRANSFORMATION,
   ACE_DIT_DENSE_FP16_TILE_LAYOUT,
   ACE_DIT_DENSE_FP16_TRANSFORMATION,
   ACE_DIT_GEMM_FP16_TRANSFORMATION,
@@ -15,6 +17,7 @@ import {
 } from "../model/manifest.js";
 import {
   ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE,
+  ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
   ACE_OPT_0037_DIT_K4_RUNTIME_PROFILE,
   ACE_OPT_0056_DIT_SELECTIVE_K4_RUNTIME_PROFILE,
   type AceDitDenseRuntimeProfile,
@@ -586,8 +589,10 @@ function requireAceDitRepeatedDenseLogicalTensor(
   const k4 =
     denseRuntimeProfile === ACE_OPT_0037_DIT_K4_RUNTIME_PROFILE ||
     denseRuntimeProfile === ACE_OPT_0056_DIT_SELECTIVE_K4_RUNTIME_PROFILE;
+  const int8 = denseRuntimeProfile === ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE;
   if (
-    !k4 && denseRuntimeProfile !== ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE
+    !k4 && !int8 &&
+    denseRuntimeProfile !== ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE
   ) {
     throw new TypeError(
       `Unknown ACE DiT dense runtime profile ${String(denseRuntimeProfile)}`,
@@ -595,13 +600,22 @@ function requireAceDitRepeatedDenseLogicalTensor(
   }
   const expectedStorageShape = k4
     ? [columns / 128, inner / 4, 4, 32, 4]
-    : expectedShape;
+    : int8
+      ? [columns / 256, inner / 32, 2_176]
+      : expectedShape;
   const expectedLayout = k4
     ? ACE_DIT_DENSE_K4_FP16_LAYOUT
-    : ACE_DIT_DENSE_FP16_TILE_LAYOUT;
+    : int8
+      ? ACE_DIT_DENSE_INT8_TILE_LAYOUT
+      : ACE_DIT_DENSE_FP16_TILE_LAYOUT;
   const expectedTransformation = k4
     ? ACE_DIT_DENSE_K4_FP16_TRANSFORMATION
-    : ACE_DIT_DENSE_FP16_TRANSFORMATION;
+    : int8
+      ? ACE_DIT_DENSE_INT8_TRANSFORMATION
+      : ACE_DIT_DENSE_FP16_TRANSFORMATION;
+  const expectedByteLength = int8
+    ? (columns / 256) * (inner / 32) * 8_704
+    : elements * 2;
   if (
     part.tensorName !== expectedName ||
     tensor.logicalTensor !== expectedName ||
@@ -611,8 +625,8 @@ function requireAceDitRepeatedDenseLogicalTensor(
     tensor.storageShape.some(
       (value, index) => value !== expectedStorageShape[index],
     ) ||
-    tensor.byteLength !== elements * 2 ||
-    tensor.dtype !== "float16" ||
+    tensor.byteLength !== expectedByteLength ||
+    tensor.dtype !== (int8 ? "uint32-int8-fp16-blocks" : "float16") ||
     tensor.layout !== expectedLayout ||
     tensor.transformation !== expectedTransformation ||
     tensor.phase !== "dit" ||
diff --git a/packages/acestep/src/webgpu/ace-dit.ts b/packages/acestep/src/webgpu/ace-dit.ts
index 66483f2..bbcf18e 100644
--- a/packages/acestep/src/webgpu/ace-dit.ts
+++ b/packages/acestep/src/webgpu/ace-dit.ts
@@ -47,6 +47,8 @@ import { AceOpt0088DensePortableKernel } from
   "./kernels/dit-dense-fp16-portable.js";
 import { AceOpt0081DenseF16InputKernel } from
   "./kernels/dit-dense-f16-input.js";
+import { AceOpt0091DenseInt8Kernel } from
+  "./kernels/dit-dense-int8-weight-only.js";
 import { AceOpt0037DenseK4ProductionKernel } from
   "./kernels/dit-dense-fp16-k4-production.js";
 import {
@@ -159,6 +161,11 @@ export type AceDitDenseGemmRuntimeConfiguration =
     }>
   /** Portable OPT-0009 port; no subgroup capability exists to declare. */
   | Readonly<{ backend: "opt-0088-dense-portable" }>
+  | Readonly<{
+      backend: "opt-0091-int8-weight-only";
+      capability: AceFixed32SubgroupCapability;
+    }>
+  | Readonly<{ backend: "opt-0091-int8-weight-only-portable" }>
   | Readonly<{
       backend: "opt-0037-k4-fp16-partials";
       capability: AceFixed32SubgroupCapability;
@@ -509,6 +516,15 @@ export function createAceDitDenseGemmKernel(
   if (configuration.backend === "opt-0088-dense-portable") {
     return AceOpt0088DensePortableKernel.create(device);
   }
+  if (configuration.backend === "opt-0091-int8-weight-only") {
+    return AceOpt0091DenseInt8Kernel.create(device, {
+      portable: false,
+      ...configuration.capability,
+    });
+  }
+  if (configuration.backend === "opt-0091-int8-weight-only-portable") {
+    return AceOpt0091DenseInt8Kernel.create(device, { portable: true });
+  }
   if (configuration.backend === "opt-0037-k4-fp16-partials") {
     return AceOpt0037DenseK4ProductionKernel.create(
       device,
diff --git a/packages/acestep/src/webgpu/dit-backend.ts b/packages/acestep/src/webgpu/dit-backend.ts
index 24cc86d..bd133bf 100644
--- a/packages/acestep/src/webgpu/dit-backend.ts
+++ b/packages/acestep/src/webgpu/dit-backend.ts
@@ -89,6 +89,7 @@ import { planAceOpt0032DenseK4Partials } from
 import {
   ACE_OPT_0009_DIT_MIXED_RESIDENT_WEIGHT_BYTES,
   ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE,
+  ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
   ACE_OPT_0037_DIT_K4_RUNTIME_PROFILE,
   ACE_OPT_0056_DIT_SELECTIVE_K4_RUNTIME_PROFILE,
   type AceDitDenseRuntimeProfile,
@@ -1047,7 +1048,9 @@ export type AceDitGemmBackend =
   | "mixed-opt-0009"
   | "mixed-opt-0037-k4"
   | "mixed-opt-0056-selective"
-  | "mixed-opt-0088-portable";
+  | "mixed-opt-0088-portable"
+  | "mixed-opt-0091"
+  | "mixed-opt-0091-portable";
 
 export interface AceDitGemmSelection {
   readonly modelProfile: AceModelProfileId;
@@ -1072,7 +1075,9 @@ export interface AceDitMixedGemmSelection {
     | "mixed-opt-0009"
     | "mixed-opt-0037-k4"
     | "mixed-opt-0056-selective"
-    | "mixed-opt-0088-portable";
+    | "mixed-opt-0088-portable"
+    | "mixed-opt-0091"
+    | "mixed-opt-0091-portable";
   readonly denseRuntimeProfile: AceDitDenseRuntimeProfile;
   readonly attentionRuntimeProfile: AceDitAttentionRuntimeProfile;
   readonly gemmConfiguration: AceDitGemmSelection["gemmConfiguration"];
@@ -1083,7 +1088,9 @@ export interface AceDitMixedGemmSelection {
         | "opt-0009-fp16-fp32"
         | "opt-0037-k4-fp16-partials"
         | "opt-0056-selective-k4-exact-down"
-        | "opt-0088-dense-portable";
+        | "opt-0088-dense-portable"
+        | "opt-0091-int8-weight-only"
+        | "opt-0091-int8-weight-only-portable";
     }
   >;
   readonly attentionConfiguration: Extract<
@@ -1168,6 +1175,7 @@ export function resolveAceDitMixedGemmSelection(
   );
   if (
     denseRuntimeProfile !== ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE &&
+    denseRuntimeProfile !== ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE &&
     denseRuntimeProfile !== ACE_OPT_0037_DIT_K4_RUNTIME_PROFILE &&
     denseRuntimeProfile !== ACE_OPT_0056_DIT_SELECTIVE_K4_RUNTIME_PROFILE
   ) {
@@ -1181,7 +1189,8 @@ export function resolveAceDitMixedGemmSelection(
         ACE_OPT_0062_DIT_QUAD_QUERY_ATTENTION_RUNTIME_PROFILE ||
       attentionProfile.id ===
         ACE_OPT_0070_DIT_QUAD_QUERY_ATTENTION_RUNTIME_PROFILE) &&
-    denseRuntimeProfile !== ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE
+    denseRuntimeProfile !== ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE &&
+    denseRuntimeProfile !== ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE
   ) {
     throw new Error(
       "OPT-0062 cannot combine with the revision-8 or selective dense profile",
@@ -1209,23 +1218,28 @@ export function resolveAceDitMixedGemmSelection(
       reference.modelProfile !== "reference-bf16" ||
       reference.backend !== "portable" ||
       reference.gemmConfiguration.backend !== "portable" ||
-      denseRuntimeProfile !== ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE ||
+      (denseRuntimeProfile !== ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE &&
+        denseRuntimeProfile !== ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE) ||
       attentionProfile.id !==
         ACE_OPT_0070_DIT_QUAD_QUERY_ATTENTION_RUNTIME_PROFILE
     ) {
       throw new Error(
         "Portable mixed DiT requires the reference-bf16 portable profile " +
-          "with the OPT-0009 dense and OPT-0070 attention runtime profiles",
+          "with an authenticated dense and OPT-0070 attention runtime profile",
       );
     }
     return Object.freeze({
       modelProfile: "reference-bf16",
-      backend: "mixed-opt-0088-portable",
+      backend: denseRuntimeProfile === ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE
+        ? "mixed-opt-0091-portable"
+        : "mixed-opt-0088-portable",
       denseRuntimeProfile,
       attentionRuntimeProfile: attentionProfile.id,
       gemmConfiguration: reference.gemmConfiguration,
       denseGemmConfiguration: Object.freeze({
-        backend: "opt-0088-dense-portable" as const,
+        backend: denseRuntimeProfile === ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE
+          ? "opt-0091-int8-weight-only-portable" as const
+          : "opt-0088-dense-portable" as const,
       }),
       attentionConfiguration: Object.freeze({ backend: "portable" as const }),
     });
@@ -1244,9 +1258,12 @@ export function resolveAceDitMixedGemmSelection(
     throw new Error("Optimized mixed DiT requires fixed 32-lane subgroups");
   }
   const capability = Object.freeze({ subgroupMinSize, subgroupMaxSize });
+  const int8 = denseRuntimeProfile === ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE;
   return Object.freeze({
     modelProfile: "reference-bf16",
-    backend: selective
+    backend: int8
+      ? "mixed-opt-0091"
+      : selective
       ? "mixed-opt-0056-selective"
       : k4
         ? "mixed-opt-0037-k4"
@@ -1258,7 +1275,9 @@ export function resolveAceDitMixedGemmSelection(
       capability,
     }),
     denseGemmConfiguration: Object.freeze({
-      backend: selective
+      backend: int8
+        ? "opt-0091-int8-weight-only"
+        : selective
         ? "opt-0056-selective-k4-exact-down"
         : k4
           ? "opt-0037-k4-fp16-partials"
@@ -5622,7 +5641,9 @@ export function planAceDitPhysicalCommandBufferCount(
     gemmBackend !== "mixed-opt-0009" &&
     gemmBackend !== "mixed-opt-0037-k4" &&
     gemmBackend !== "mixed-opt-0056-selective" &&
-    gemmBackend !== "mixed-opt-0088-portable"
+    gemmBackend !== "mixed-opt-0088-portable" &&
+    gemmBackend !== "mixed-opt-0091" &&
+    gemmBackend !== "mixed-opt-0091-portable"
   ) {
     throw new TypeError(
       `Unknown ACE DiT GEMM backend ${String(gemmBackend)}`,
@@ -5631,7 +5652,9 @@ export function planAceDitPhysicalCommandBufferCount(
   const gemm = (rows: number, inner: number, columns: number): AceGemmShape =>
     Object.freeze({ rows, inner, columns });
   const planGemm = (shape: AceGemmShape): AceCooperativeGemmPlan =>
-    gemmBackend === "portable" || gemmBackend === "mixed-opt-0088-portable"
+    gemmBackend === "portable" ||
+      gemmBackend === "mixed-opt-0088-portable" ||
+      gemmBackend === "mixed-opt-0091-portable"
       ? planAceTiledGemm(shape)
       : planAceSubgroupGemm(shape);
   const planDenseGemm = (shape: AceGemmShape): AceCooperativeGemmPlan =>
@@ -5639,7 +5662,9 @@ export function planAceDitPhysicalCommandBufferCount(
       gemmBackend === "mixed-opt-0056-selective"
       ? planAceOpt0032DenseK4Partials(shape)
       : gemmBackend === "mixed-opt-0009" ||
-          gemmBackend === "mixed-opt-0088-portable"
+          gemmBackend === "mixed-opt-0088-portable" ||
+          gemmBackend === "mixed-opt-0091" ||
+          gemmBackend === "mixed-opt-0091-portable"
         ? planAceOpt0009DenseGemm(shape)
         : planGemm(shape);
   const ranges = (shape: AceGemmShape): number =>
@@ -5690,6 +5715,7 @@ export function planAceDitPhysicalCommandBufferCount(
   ) => {
     if (
       (gemmBackend !== "mixed-opt-0009" &&
+        gemmBackend !== "mixed-opt-0091" &&
         gemmBackend !== "mixed-opt-0037-k4" &&
         gemmBackend !== "mixed-opt-0056-selective") ||
       !isAceFixed32TiledFullAttentionShape(shape)
@@ -5711,6 +5737,7 @@ export function planAceDitPhysicalCommandBufferCount(
     Array.from({ length: LAYER_COUNT }, (_, layerIndex) => {
       if (
         gemmBackend !== "mixed-opt-0009" &&
+        gemmBackend !== "mixed-opt-0091" &&
         gemmBackend !== "mixed-opt-0037-k4" &&
         gemmBackend !== "mixed-opt-0056-selective"
       ) {
diff --git a/packages/acestep/src/webgpu/dit-fp16-package.ts b/packages/acestep/src/webgpu/dit-fp16-package.ts
index 3acfc10..8ae354f 100644
--- a/packages/acestep/src/webgpu/dit-fp16-package.ts
+++ b/packages/acestep/src/webgpu/dit-fp16-package.ts
@@ -35,6 +35,23 @@ export const ACE_OPT_0089_DIT_FAKE_QUANT_MANIFEST_SHA256 =
 export const ACE_OPT_0089_DIT_FAKE_QUANT_MANIFEST_BYTES =
   ACE_OPT_0009_DIT_DENSE_MANIFEST_BYTES;
 
+export const ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256 =
+  "a3233c9f97bc151b5ffa2a6cd8c9ecaee4e555497ee6fda20b70becaf7d55da1" as const;
+export const ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES = 262_613 as const;
+export const ACE_OPT_0091_DIT_INT8_CONVERTER_REVISION = 9 as const;
+export const ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE =
+  "opt-0091-int8-weight-only-v1" as const;
+export const ACE_OPT_0091_DIT_INT8_KERNEL_SET_ID =
+  "opt-0091-int8-weight-only-fixed32-v1" as const;
+export const ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID =
+  "opt-0091-int8-weight-only-portable-v1" as const;
+export const ACE_OPT_0091_DIT_INT8_LAYER_BYTES = 1_699_602_432 as const;
+export const ACE_OPT_0091_DIT_INT8_RESIDENT_WEIGHT_BYTES =
+  1_829_712_128 as const;
+export const ACE_OPT_0091_DIT_INT8_WEIGHT_FILES = Object.freeze([
+  ...ACE_OPT_0009_DIT_DENSE_WEIGHT_FILES,
+]);
+
 export const ACE_OPT_0037_DIT_K4_MANIFEST_SHA256 =
   "a2f70c123fb7c4dbc3b51be68b4b494107c13b575ad2bed68c639791c93574d1" as const;
 export const ACE_OPT_0037_DIT_K4_MANIFEST_BYTES = 257_789 as const;
@@ -65,6 +82,7 @@ export const ACE_OPT_0088_DIT_DENSE_PORTABLE_KERNEL_SET_ID =
 
 export type AceDitDenseRuntimeProfile =
   | typeof ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE
+  | typeof ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE
   | typeof ACE_OPT_0037_DIT_K4_RUNTIME_PROFILE
   | typeof ACE_OPT_0056_DIT_SELECTIVE_K4_RUNTIME_PROFILE;
 
@@ -123,6 +141,30 @@ export function requireAceOpt0089DitFakeQuantPackageIdentity(
   );
 }
 
+export function requireAceOpt0091DitInt8PackageIdentity(
+  loaded: AceLoadedPackageManifest,
+): void {
+  const manifest = loaded.manifest;
+  const weightFiles = manifest.files.filter((file) => file.kind === "weights");
+  if (
+    loaded.manifestSha256 !== ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256 ||
+    loaded.manifestByteLength !== ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES ||
+    manifest.profile !== "int8-dit-dense-experimental" ||
+    manifest.provenance.converterRevision !==
+      ACE_OPT_0091_DIT_INT8_CONVERTER_REVISION ||
+    weightFiles.length !== ACE_OPT_0091_DIT_INT8_WEIGHT_FILES.length ||
+    ACE_OPT_0091_DIT_INT8_WEIGHT_FILES.some((name, index) =>
+      weightFiles[index]?.name !== name ||
+      weightFiles[index]?.byteLength !==
+        (index % 2 === 0 ? 68_584_448 : 2_232_320)
+    ) ||
+    weightFiles.reduce((sum, file) => sum + file.byteLength, 0) !==
+      ACE_OPT_0091_DIT_INT8_LAYER_BYTES
+  ) {
+    throw new Error("OPT-0091 packed INT8 DiT package identity changed");
+  }
+}
+
 function requireAceRev7DitDensePackageIdentity(
   loaded: AceLoadedPackageManifest,
   expectedManifestSha256: string,
diff --git a/packages/acestep/src/webgpu/dit-graph.ts b/packages/acestep/src/webgpu/dit-graph.ts
index 30a0018..2f2af0d 100644
--- a/packages/acestep/src/webgpu/dit-graph.ts
+++ b/packages/acestep/src/webgpu/dit-graph.ts
@@ -52,6 +52,7 @@ import {
 import {
   ACE_OPT_0009_DIT_DENSE_KERNEL_SET_ID,
   ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE,
+  ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
   ACE_OPT_0037_DIT_K4_LAYER_BYTES,
   ACE_OPT_0037_DIT_K4_KERNEL_SET_ID,
   ACE_OPT_0037_DIT_K4_RESIDENT_WEIGHT_BYTES,
@@ -623,9 +624,12 @@ export class AceDitResidentModel implements AceDitGraphModel {
       ownedReferencePhase.packageManifest.profile !== "reference" ||
       ownedDensePhase.phases.length !== 1 ||
       ownedDensePhase.phases[0] !== "dit" ||
-      ownedDensePhase.packageManifest.profile !==
-        "fp16-dit-dense-experimental" ||
+      (ownedDensePhase.packageManifest.profile !==
+          "fp16-dit-dense-experimental" &&
+        ownedDensePhase.packageManifest.profile !==
+          "int8-dit-dense-experimental") ||
       (denseRuntimeProfile !== ACE_OPT_0009_DIT_DENSE_RUNTIME_PROFILE &&
+        denseRuntimeProfile !== ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE &&
         denseRuntimeProfile !== ACE_OPT_0037_DIT_K4_RUNTIME_PROFILE &&
         denseRuntimeProfile !== ACE_OPT_0056_DIT_SELECTIVE_K4_RUNTIME_PROFILE)
     ) {
diff --git a/packages/acestep/src/webgpu/kernels/dit-dense-int8-weight-only.ts b/packages/acestep/src/webgpu/kernels/dit-dense-int8-weight-only.ts
new file mode 100644
index 0000000..6982f70
--- /dev/null
+++ b/packages/acestep/src/webgpu/kernels/dit-dense-int8-weight-only.ts
@@ -0,0 +1,359 @@
+import { ACE_DIT_DENSE_INT8_TILE_LAYOUT } from "../../model/manifest.js";
+import {
+  checkedAceProduct,
+  requireAceBindingBytes,
+  requireAceDisjointOutput,
+} from "./correctness-utils.js";
+import {
+  ACE_OPT_0009_DENSE_SUBGROUP_SIZE,
+  ACE_OPT_0009_DENSE_TILE_COLUMNS,
+  ACE_OPT_0009_DENSE_TILE_INNER,
+  ACE_OPT_0009_DENSE_TILE_ROWS,
+  ACE_OPT_0009_DENSE_WORKGROUP_SIZE,
+  planAceOpt0009DenseGemm,
+  type AceOpt0009DenseGemmPlan,
+} from "./dit-dense-fp16.js";
+import type {
+  AceGemmBufferBindings,
+  AceGemmDispatch,
+  AceGemmKernel,
+  AceGemmShape,
+} from "./gemm.js";
+
+export const ACE_OPT_0091_DENSE_INT8_KERNEL_ID =
+  "opt-0091-dense-int8-fp16-scale-fp32-fixed32-v1";
+export const ACE_OPT_0091_DENSE_INT8_PORTABLE_KERNEL_ID =
+  "opt-0091-dense-int8-fp16-scale-fp32-portable-v1";
+export const ACE_OPT_0091_DENSE_INT8_WEIGHT_LAYOUT =
+  ACE_DIT_DENSE_INT8_TILE_LAYOUT;
+export const ACE_OPT_0091_DENSE_INT8_TILE_QUANTIZED_BYTES =
+  ACE_OPT_0009_DENSE_TILE_INNER * ACE_OPT_0009_DENSE_TILE_COLUMNS;
+export const ACE_OPT_0091_DENSE_INT8_TILE_SCALE_BYTES =
+  ACE_OPT_0009_DENSE_TILE_COLUMNS * 2;
+export const ACE_OPT_0091_DENSE_INT8_TILE_BYTES =
+  ACE_OPT_0091_DENSE_INT8_TILE_QUANTIZED_BYTES +
+  ACE_OPT_0091_DENSE_INT8_TILE_SCALE_BYTES;
+export const ACE_OPT_0091_DENSE_INT8_TILE_WORDS =
+  ACE_OPT_0091_DENSE_INT8_TILE_BYTES / 4;
+
+const LANES = ACE_OPT_0009_DENSE_SUBGROUP_SIZE;
+const SLICES = ACE_OPT_0009_DENSE_WORKGROUP_SIZE / LANES;
+const ROWS_PER_SLICE = ACE_OPT_0009_DENSE_TILE_ROWS / SLICES;
+const OUTPUTS_PER_LANE = ACE_OPT_0009_DENSE_TILE_COLUMNS / LANES;
+const QUANTIZED_WORDS_PER_INNER = ACE_OPT_0009_DENSE_TILE_COLUMNS / 4;
+const QUANTIZED_WORDS_PER_TILE =
+  ACE_OPT_0091_DENSE_INT8_TILE_QUANTIZED_BYTES / 4;
+
+export interface AceOpt0091DenseInt8Plan extends Omit<
+  AceOpt0009DenseGemmPlan,
+  "packedWeightStorageShape"
+> {
+  readonly packedWeightBytes: number;
+  readonly packedWeightStorageShape: readonly [number, number, number];
+}
+
+export interface AceOpt0091DenseInt8Dispatch extends AceGemmDispatch {
+  readonly kernelId:
+    | typeof ACE_OPT_0091_DENSE_INT8_KERNEL_ID
+    | typeof ACE_OPT_0091_DENSE_INT8_PORTABLE_KERNEL_ID;
+  readonly weightLayout: typeof ACE_OPT_0091_DENSE_INT8_WEIGHT_LAYOUT;
+  readonly plan: AceOpt0091DenseInt8Plan;
+}
+
+export class AceOpt0091DenseInt8Kernel implements AceGemmKernel {
+  private readonly compiled = new Map<string, Promise<GPUComputePipeline>>();
+  private destroyed = false;
+
+  private constructor(
+    private readonly device: GPUDevice,
+    private readonly portable: boolean,
+  ) {}
+
+  static create(
+    device: GPUDevice,
+    configuration: Readonly<{
+      portable: boolean;
+      subgroupMinSize?: number;
+      subgroupMaxSize?: number;
+    }>,
+  ): AceOpt0091DenseInt8Kernel {
+    if (!device.features.has("shader-f16")) {
+      throw new Error("OPT-0091 dense INT8 requires WebGPU shader-f16");
+    }
+    if (
+      !configuration.portable &&
+      (!device.features.has("subgroups") ||
+        configuration.subgroupMinSize !== LANES ||
+        configuration.subgroupMaxSize !== LANES)
+    ) {
+      throw new Error(
+        "OPT-0091 subgroup dense INT8 requires fixed 32-lane subgroups",
+      );
+    }
+    if (
+      device.limits.maxComputeInvocationsPerWorkgroup <
+        ACE_OPT_0009_DENSE_WORKGROUP_SIZE ||
+      device.limits.maxComputeWorkgroupSizeX < ACE_OPT_0009_DENSE_WORKGROUP_SIZE
+    ) {
+      throw new Error(
+        `OPT-0091 dense INT8 requires WG${ACE_OPT_0009_DENSE_WORKGROUP_SIZE}`,
+      );
+    }
+    return new AceOpt0091DenseInt8Kernel(device, configuration.portable);
+  }
+
+  async createDispatch(
+    label: string,
+    shape: AceGemmShape,
+    bindings: AceGemmBufferBindings,
+  ): Promise<AceOpt0091DenseInt8Dispatch> {
+    if (this.destroyed)
+      throw new Error("OPT-0091 dense INT8 kernel was destroyed");
+    if (bindings.bias !== undefined) {
+      throw new Error("OPT-0091 repeated-layer dense GEMMs do not accept bias");
+    }
+    const base = planAceOpt0009DenseGemm(shape);
+    const packedWeightBytes = checkedAceProduct(
+      [base.columnTiles, base.innerTiles, ACE_OPT_0091_DENSE_INT8_TILE_BYTES],
+      `${label} packed weight bytes`,
+    );
+    const plan: AceOpt0091DenseInt8Plan = Object.freeze({
+      ...base,
+      packedWeightBytes,
+      packedWeightStorageShape: Object.freeze([
+        base.columnTiles,
+        base.innerTiles,
+        ACE_OPT_0091_DENSE_INT8_TILE_WORDS,
+      ]) as readonly [number, number, number],
+    });
+    const activationBytes = checkedAceProduct(
+      [plan.activationElements, 4],
+      `${label} activation bytes`,
+    );
+    const outputBytes = checkedAceProduct(
+      [plan.outputElements, 4],
+      `${label} output bytes`,
+    );
+    requireAceBindingBytes(
+      bindings.activation,
+      activationBytes,
+      `${label} activation`,
+    );
+    requireAceBindingBytes(
+      bindings.weight,
+      packedWeightBytes,
+      `${label} weight`,
+    );
+    requireAceBindingBytes(bindings.output, outputBytes, `${label} output`);
+    requireAceDisjointOutput(
+      exactBinding(bindings.output, outputBytes),
+      [
+        exactBinding(bindings.activation, activationBytes),
+        exactBinding(bindings.weight, packedWeightBytes),
+      ],
+      label,
+    );
+    const pipeline = await this.pipelineFor(shape);
+    if (this.destroyed) {
+      throw new Error(
+        "OPT-0091 dense INT8 kernel was destroyed while compiling",
+      );
+    }
+    const bindGroup = this.device.createBindGroup({
+      label: `${label}-opt-0091-bindings`,
+      layout: pipeline.getBindGroupLayout(0),
+      entries: [
+        {
+          binding: 0,
+          resource: exactBinding(bindings.activation, activationBytes),
+        },
+        {
+          binding: 1,
+          resource: exactBinding(bindings.weight, packedWeightBytes),
+        },
+        { binding: 2, resource: exactBinding(bindings.output, outputBytes) },
+      ],
+    });
+    const kernelId = this.portable
+      ? ACE_OPT_0091_DENSE_INT8_PORTABLE_KERNEL_ID
+      : ACE_OPT_0091_DENSE_INT8_KERNEL_ID;
+    return Object.freeze({
+      label,
+      kernelId,
+      weightLayout: ACE_OPT_0091_DENSE_INT8_WEIGHT_LAYOUT,
+      plan,
+      rangeCount: 1,
+      encodeRange(pass: GPUComputePassEncoder, rangeIndex: number): void {
+        if (rangeIndex !== 0)
+          throw new RangeError(`${label} OPT-0091 range must be zero`);
+        encode(pass, pipeline, bindGroup, plan);
+      },
+      encode(pass: GPUComputePassEncoder): void {
+        encode(pass, pipeline, bindGroup, plan);
+      },
+    });
+  }
+
+  destroy(): void {
+    if (this.destroyed) return;
+    this.destroyed = true;
+    this.compiled.clear();
+  }
+
+  private pipelineFor(shape: AceGemmShape): Promise<GPUComputePipeline> {
+    const key = `${shape.rows}x${shape.inner}x${shape.columns}`;
+    const existing = this.compiled.get(key);
+    if (existing !== undefined) return existing;
+    const created = compile(this.device, shape, this.portable);
+    this.compiled.set(key, created);
+    void created.catch(() => {
+      if (this.compiled.get(key) === created) this.compiled.delete(key);
+    });
+    return created;
+  }
+}
+
+export function aceOpt0091DenseInt8Wgsl(
+  shape: AceGemmShape,
+  portable: boolean,
+): string {
+  const plan = planAceOpt0009DenseGemm(shape);
+  const declarations = Array.from(
+    { length: ROWS_PER_SLICE },
+    (_, row) =>
+      `  var acc${row}_0 = vec4<f32>(0.0);\n  var acc${row}_1 = vec4<f32>(0.0);`,
+  ).join("\n");
+  const reads = Array.from({ length: ROWS_PER_SLICE }, (_, row) =>
+    portable
+      ? `      let a${row} = staged_a[staged_base + ${row}u];`
+      : `      let a${row} = subgroupBroadcast(lane_a, ${row}u);`,
+  ).join("\n");
+  const contractions = Array.from(
+    { length: ROWS_PER_SLICE },
+    (_, row) =>
+      `      acc${row}_0 = acc${row}_0 + vec4<f32>(f32(a${row})) * vec4<f32>(b0);\n` +
+      `      acc${row}_1 = acc${row}_1 + vec4<f32>(f32(a${row})) * vec4<f32>(b1);`,
+  ).join("\n");
+  const stores = Array.from(
+    { length: ROWS_PER_SLICE },
+    (_, row) => `
+  {
+    let row = row_base + ${row}u;
+    if (row < ROWS) {
+      let vector_base = row * (COLUMNS / 4u) + column_base / 4u;
+      output[vector_base] = acc${row}_0;
+      output[vector_base + 1u] = acc${row}_1;
+    }
+  }`,
+  ).join("\n");
+  const feature = portable ? "" : "enable subgroups;\n";
+  const builtins = portable
+    ? "@builtin(local_invocation_index) local_index: u32,"
+    : "@builtin(subgroup_invocation_id) lane: u32,\n  @builtin(subgroup_id) slice: u32,\n  @builtin(subgroup_size) subgroup_size: u32,";
+  const laneSetup = portable
+    ? `  let slice = local_index / ${LANES}u;\n  let lane = local_index % ${LANES}u;`
+    : `  if (subgroup_size != ${LANES}u || slice >= ${SLICES}u) { return; }`;
+  const stagingDeclaration = portable
+    ? `var<workgroup> staged_a: array<f16, ${SLICES * ROWS_PER_SLICE}>;`
+    : "";
+  const stageWrite = portable
+    ? `      if (lane < ${ROWS_PER_SLICE}u) { staged_a[staged_base + lane] = lane_a; }\n      workgroupBarrier();`
+    : "";
+  const stageEnd = portable ? "      workgroupBarrier();" : "";
+  return `
+enable f16;
+${feature}
+const ROWS = ${plan.rows}u;
+const INNER = ${plan.inner}u;
+const COLUMNS = ${plan.columns}u;
+const INNER_TILES = ${plan.innerTiles}u;
+@group(0) @binding(0) var<storage, read> activation: array<f32>;
+@group(0) @binding(1) var<storage, read> weight: array<u32>;
+@group(0) @binding(2) var<storage, read_write> output: array<vec4<f32>>;
+${stagingDeclaration}
+fn unpack_i8x4(word: u32) -> vec4<f16> {
+  let raw = vec4<u32>(word & 255u, (word >> 8u) & 255u, (word >> 16u) & 255u, word >> 24u);
+  let positive = vec4<i32>(raw);
+  let signed = select(positive, positive - vec4<i32>(256), raw >= vec4<u32>(128));
+  return vec4<f16>(signed);
+}
+@compute @workgroup_size(${ACE_OPT_0009_DENSE_WORKGROUP_SIZE}, 1, 1)
+fn main(
+  ${builtins}
+  @builtin(workgroup_id) group: vec3<u32>,
+) {
+  if (group.x >= ${plan.columnTiles}u || group.y >= ${plan.rowTiles}u || group.z != 0u) { return; }
+${laneSetup}
+  let staged_base = slice * ${ROWS_PER_SLICE}u;
+  let row_base = group.y * ${ACE_OPT_0009_DENSE_TILE_ROWS}u + slice * ${ROWS_PER_SLICE}u;
+  let column_base = group.x * ${ACE_OPT_0009_DENSE_TILE_COLUMNS}u + lane * ${OUTPUTS_PER_LANE}u;
+${declarations}
+  for (var inner_tile = 0u; inner_tile < INNER_TILES; inner_tile += 1u) {
+    let tile_base = (group.x * INNER_TILES + inner_tile) * ${ACE_OPT_0091_DENSE_INT8_TILE_WORDS}u;
+    let scale_base = tile_base + ${QUANTIZED_WORDS_PER_TILE}u + lane * 4u;
+    let s01 = unpack2x16float(weight[scale_base]);
+    let s23 = unpack2x16float(weight[scale_base + 1u]);
+    let s45 = unpack2x16float(weight[scale_base + 2u]);
+    let s67 = unpack2x16float(weight[scale_base + 3u]);
+    let scale0 = vec4<f16>(f16(s01.x), f16(s01.y), f16(s23.x), f16(s23.y));
+    let scale1 = vec4<f16>(f16(s45.x), f16(s45.y), f16(s67.x), f16(s67.y));
+    for (var inner_in_tile = 0u; inner_in_tile < ${ACE_OPT_0009_DENSE_TILE_INNER}u; inner_in_tile += 1u) {
+      let inner = inner_tile * ${ACE_OPT_0009_DENSE_TILE_INNER}u + inner_in_tile;
+      var lane_a = 0.0h;
+      let lane_row = row_base + lane;
+      if (lane < ${ROWS_PER_SLICE}u && lane_row < ROWS) { lane_a = f16(activation[lane_row * INNER + inner]); }
+${stageWrite}
+      let q_base = tile_base + inner_in_tile * ${QUANTIZED_WORDS_PER_INNER}u + lane * 2u;
+      let b0 = unpack_i8x4(weight[q_base]) * scale0;
+      let b1 = unpack_i8x4(weight[q_base + 1u]) * scale1;
+${reads}
+${contractions}
+${stageEnd}
+    }
+  }
+${stores}
+}
+`;
+}
+
+async function compile(
+  device: GPUDevice,
+  shape: AceGemmShape,
+  portable: boolean,
+): Promise<GPUComputePipeline> {
+  const label = `ace-opt-0091-${portable ? "portable" : "subgroup"}-${shape.rows}x${shape.inner}x${shape.columns}`;
+  const module = device.createShaderModule({
+    label,
+    code: aceOpt0091DenseInt8Wgsl(shape, portable),
+  });
+  const info = await module.getCompilationInfo();
+  const errors = info.messages.filter((message) => message.type === "error");
+  if (errors.length !== 0) {
+    throw new Error(
+      `${label} WGSL compilation failed:\n${errors.map((message) => `${message.lineNum}:${message.linePos} ${message.message}`).join("\n")}`,
+    );
+  }
+  return await device.createComputePipelineAsync({
+    label,
+    layout: "auto",
+    compute: { module, entryPoint: "main" },
+  });
+}
+
+function encode(
+  pass: GPUComputePassEncoder,
+  pipeline: GPUComputePipeline,
+  bindGroup: GPUBindGroup,
+  plan: AceOpt0091DenseInt8Plan,
+): void {
+  pass.setPipeline(pipeline);
+  pass.setBindGroup(0, bindGroup);
+  pass.dispatchWorkgroups(plan.columnTiles, plan.rowTiles, 1);
+}
+
+function exactBinding(
+  binding: GPUBufferBinding,
+  size: number,
+): GPUBufferBinding {
+  return { buffer: binding.buffer, offset: binding.offset ?? 0, size };
+}
diff --git a/packages/acestep/src/webgpu/kernels/gemm.ts b/packages/acestep/src/webgpu/kernels/gemm.ts
index f08befa..072ac46 100644
--- a/packages/acestep/src/webgpu/kernels/gemm.ts
+++ b/packages/acestep/src/webgpu/kernels/gemm.ts
@@ -2,6 +2,7 @@ import type { AceModelProfileId } from "../capabilities.js";
 import {
   ACE_DIT_DENSE_K4_FP16_LAYOUT,
   ACE_DIT_DENSE_FP16_TILE_LAYOUT,
+  ACE_DIT_DENSE_INT8_TILE_LAYOUT,
   ACE_DIT_GEMM_TILE_LAYOUT,
 } from "../../model/manifest.js";
 import { createAceScopedBuffers } from "../scoped-buffer-allocation.js";
@@ -26,6 +27,7 @@ export type AceGemmWeightLayout =
   | "source-row-major"
   | typeof ACE_DIT_GEMM_WEIGHT_LAYOUT
   | typeof ACE_DIT_DENSE_FP16_TILE_LAYOUT
+  | typeof ACE_DIT_DENSE_INT8_TILE_LAYOUT
   | typeof ACE_DIT_DENSE_K4_FP16_LAYOUT;
 export const ACE_TILED_GEMM_WORKGROUP_BYTES =
   (TILED_A_VALUES + TILED_B_VALUES) * Float32Array.BYTES_PER_ELEMENT;
diff --git a/packages/acestep/test/opt-0010-planner-token-profiler.test.ts b/packages/acestep/test/opt-0010-planner-token-profiler.test.ts
index a5b5a38..4bffe85 100644
--- a/packages/acestep/test/opt-0010-planner-token-profiler.test.ts
+++ b/packages/acestep/test/opt-0010-planner-token-profiler.test.ts
@@ -494,6 +494,12 @@ describe("OPT-0010 pure planner token attribution", () => {
       const actual = createHash("sha256")
         .update(readFileSync(resolve(process.cwd(), file)))
         .digest("hex");
+      if (file === "src/webgpu/kernels/gemm.ts") {
+        // OPT-0091 extends the shared layout type. Preserve this experiment's
+        // recorded source hash while acknowledging the later owned change.
+        expect(actual, file).not.toBe(expectedSha256);
+        continue;
+      }
       expect(actual, file).toBe(expectedSha256);
     }
     const attribution = createAceOpt0010PlannerTokenAttribution(
diff --git a/packages/acestep/test/opt-0012-compact-semantic-head-ab-contract.test.ts b/packages/acestep/test/opt-0012-compact-semantic-head-ab-contract.test.ts
index e8543fd..9f09e99 100644
--- a/packages/acestep/test/opt-0012-compact-semantic-head-ab-contract.test.ts
+++ b/packages/acestep/test/opt-0012-compact-semantic-head-ab-contract.test.ts
@@ -611,8 +611,9 @@ describe("OPT-0012 compact semantic head browser A/B/C contract", () => {
   it("preserves its frozen source identity and authenticates unchanged surfaces", () => {
     for (const [path, expected] of Object.entries(OPT_0012_SOURCE_IDENTITIES)) {
       const source = readFileSync(new URL(`../${path}`, import.meta.url));
-      if (path === "src/model/package.ts") {
-        // OPT-0090 owns the evolved loader identity. Keep this experiment's
+      if (path === "src/model/package.ts" || path === "src/model/manifest.ts" ||
+        path === "src/webgpu/kernels/gemm.ts") {
+        // OPT-0090/0091 own the evolved package identities. Keep this experiment's
         // recorded hash frozen so its old harness still fails closed.
         expect(createHash("sha256").update(source).digest("hex"), path)
           .not.toBe(expected);
diff --git a/packages/acestep/test/opt-0012-compact-semantic-head.test.ts b/packages/acestep/test/opt-0012-compact-semantic-head.test.ts
index 0021d3b..6f19c6d 100644
--- a/packages/acestep/test/opt-0012-compact-semantic-head.test.ts
+++ b/packages/acestep/test/opt-0012-compact-semantic-head.test.ts
@@ -91,7 +91,12 @@ describe("OPT-0012 compact semantic head static plan", () => {
       const actualSha256 = createHash("sha256")
         .update(readFileSync(resolve(process.cwd(), file)))
         .digest("hex");
-      expect(actualSha256, file).toBe(expectedSha256);
+      if (file === "src/model/manifest.ts" || file === "src/webgpu/kernels/gemm.ts") {
+        // OPT-0091 owns these later package-layout extensions.
+        expect(actualSha256, file).not.toBe(expectedSha256);
+      } else {
+        expect(actualSha256, file).toBe(expectedSha256);
+      }
     }
   });
 
diff --git a/packages/acestep/test/opt-0077-result-contract.test.ts b/packages/acestep/test/opt-0077-result-contract.test.ts
index 84e7086..bf36972 100644
--- a/packages/acestep/test/opt-0077-result-contract.test.ts
+++ b/packages/acestep/test/opt-0077-result-contract.test.ts
@@ -208,7 +208,7 @@ describe("OPT-0077 closed result contract", () => {
   });
 
   it("keeps the ledger ID and written disposition synchronized", () => {
-    expect(ledger).toContain("Next available ID: `OPT-0091`");
+    expect(ledger).toContain("Next available ID: `OPT-0092`");
     const row = ledger.split("\n").find((line) =>
       line.startsWith("| OPT-0077 |"));
     expect(row).toContain("| negative | abandoned |");
diff --git a/packages/acestep/test/opt-0078-result-contract.test.ts b/packages/acestep/test/opt-0078-result-contract.test.ts
index b592f55..c3a390f 100644
--- a/packages/acestep/test/opt-0078-result-contract.test.ts
+++ b/packages/acestep/test/opt-0078-result-contract.test.ts
@@ -196,7 +196,7 @@ describe("OPT-0078 closed result contract", () => {
       trajectoryOrListeningClaim: false,
       unchangedTimingRetryAuthorized: false,
     });
-    expect(ledger).toContain("Next available ID: `OPT-0091`");
+    expect(ledger).toContain("Next available ID: `OPT-0092`");
     const row = ledger.split("\n").find((line) =>
       line.startsWith("| OPT-0078 |"));
     expect(row).toContain("| inconclusive | benchmark-only |");
diff --git a/packages/acestep/test/opt-0079-result-contract.test.ts b/packages/acestep/test/opt-0079-result-contract.test.ts
index 00c72cd..80b3ceb 100644
--- a/packages/acestep/test/opt-0079-result-contract.test.ts
+++ b/packages/acestep/test/opt-0079-result-contract.test.ts
@@ -297,7 +297,7 @@ describe("OPT-0079 closed result contract", () => {
       trajectoryOrListeningClaim: false,
       unchangedTimingRetryAuthorized: false,
     });
-    expect(ledger).toContain("Next available ID: `OPT-0091`");
+    expect(ledger).toContain("Next available ID: `OPT-0092`");
     const row = ledger.split("\n").find((line) =>
       line.startsWith("| OPT-0079 |"));
     expect(row).toContain("| inconclusive | benchmark-only |");
diff --git a/packages/acestep/test/opt-0081-registration-contract.test.ts b/packages/acestep/test/opt-0081-registration-contract.test.ts
index c84982d..939618a 100644
--- a/packages/acestep/test/opt-0081-registration-contract.test.ts
+++ b/packages/acestep/test/opt-0081-registration-contract.test.ts
@@ -49,7 +49,7 @@ describe("OPT-0081 registration contract", () => {
     expect(RECORD).toContain(
       "`bbe180bf7feb59272a5d5f7afbafb3877afee416`",
     );
-    expect(LEDGER).toContain("Next available ID: `OPT-0091`");
+    expect(LEDGER).toContain("Next available ID: `OPT-0092`");
     const rows = LEDGER.split("\n").filter((line) =>
       line.startsWith("| OPT-0081 |")
     );
diff --git a/packages/acestep/test/opt-0090-int8-quality-preview.test.ts b/packages/acestep/test/opt-0090-int8-quality-preview.test.ts
index 5a32e77..d83d1cc 100644
--- a/packages/acestep/test/opt-0090-int8-quality-preview.test.ts
+++ b/packages/acestep/test/opt-0090-int8-quality-preview.test.ts
@@ -89,6 +89,13 @@ describe("OPT-0090 INT8 quality preview", () => {
     };
     for (const [path, expected] of Object.entries(identities)) {
       const source = readFileSync(new URL(`../${path}`, import.meta.url));
+      if (path !== "src/model/package.ts") {
+        // OPT-0091 replaces the public selector with a packed runtime while
+        // retaining this historical fake-quant identity as a frozen record.
+        expect(createHash("sha256").update(source).digest("hex"), path)
+          .not.toBe(expected);
+        continue;
+      }
       expect(createHash("sha256").update(source).digest("hex"), path)
         .toBe(expected);
     }
diff --git a/packages/acestep/test/opt-0091-packed-int8-runtime.test.ts b/packages/acestep/test/opt-0091-packed-int8-runtime.test.ts
new file mode 100644
index 0000000..cb8cf76
--- /dev/null
+++ b/packages/acestep/test/opt-0091-packed-int8-runtime.test.ts
@@ -0,0 +1,101 @@
+import { describe, expect, it } from "vitest";
+
+import { isAceClientMessage } from "../src/runtime/protocol.js";
+import { resolveAceDitDensePackageRuntimeIdentity } from "../src/runtime/webgpu-pipeline.js";
+import { resolveAceDitMixedGemmSelection } from "../src/webgpu/dit-backend.js";
+import {
+  ACE_OPT_0091_DIT_INT8_KERNEL_SET_ID,
+  ACE_OPT_0091_DIT_INT8_LAYER_BYTES,
+  ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES,
+  ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256,
+  ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID,
+  ACE_OPT_0091_DIT_INT8_RESIDENT_WEIGHT_BYTES,
+  ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
+} from "../src/webgpu/dit-fp16-package.js";
+import {
+  ACE_OPT_0091_DENSE_INT8_TILE_BYTES,
+  ACE_OPT_0091_DENSE_INT8_TILE_WORDS,
+  aceOpt0091DenseInt8Wgsl,
+} from "../src/webgpu/kernels/dit-dense-int8-weight-only.js";
+import {
+  ACE_REFERENCE_PORTABLE_PROFILE,
+  ACE_REFERENCE_SUBGROUP_PROFILE,
+} from "../src/webgpu/capabilities.js";
+import { testInitializeMessage } from "./runtime-fixtures.js";
+
+describe("OPT-0091 packed INT8 runtime", () => {
+  const packedPackage = {
+    manifestUrl: "https://example.test/dit-int8-packed/manifest.json",
+    manifestSha256: ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256,
+    runtimeProfile: ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
+  } as const;
+
+  it("pins the compressed package identity in the public protocol", () => {
+    const base = testInitializeMessage();
+    const message = {
+      ...base,
+      configuration: { ...base.configuration, ditDensePackage: packedPackage },
+    };
+    expect(isAceClientMessage(message)).toBe(true);
+    expect(resolveAceDitDensePackageRuntimeIdentity(packedPackage)).toEqual({
+      role: "opt-0091-packed-int8-preview",
+      manifestSha256: ACE_OPT_0091_DIT_INT8_MANIFEST_SHA256,
+      manifestByteLength: ACE_OPT_0091_DIT_INT8_MANIFEST_BYTES,
+      runtimeProfile: ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
+      kernelSetId: ACE_OPT_0091_DIT_INT8_KERNEL_SET_ID,
+      layerBytes: ACE_OPT_0091_DIT_INT8_LAYER_BYTES,
+      residentWeightBytes: ACE_OPT_0091_DIT_INT8_RESIDENT_WEIGHT_BYTES,
+    });
+    expect(
+      resolveAceDitDensePackageRuntimeIdentity(packedPackage, "portable"),
+    ).toMatchObject({
+      kernelSetId: ACE_OPT_0091_DIT_INT8_PORTABLE_KERNEL_SET_ID,
+    });
+  });
+
+  it("selects packed kernels for subgroup and portable adapters", () => {
+    expect(
+      resolveAceDitMixedGemmSelection(
+        ACE_REFERENCE_SUBGROUP_PROFILE,
+        32,
+        32,
+        ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
+        "opt-0070-fixed32-quad-query32-full-self-production-v1",
+        2_250,
+        98,
+      ),
+    ).toMatchObject({
+      backend: "mixed-opt-0091",
+      denseGemmConfiguration: { backend: "opt-0091-int8-weight-only" },
+    });
+    expect(
+      resolveAceDitMixedGemmSelection(
+        ACE_REFERENCE_PORTABLE_PROFILE,
+        undefined,
+        undefined,
+        ACE_OPT_0091_DIT_INT8_RUNTIME_PROFILE,
+        "opt-0070-fixed32-quad-query32-full-self-production-v1",
+        2_250,
+        98,
+      ),
+    ).toMatchObject({
+      backend: "mixed-opt-0091-portable",
+      denseGemmConfiguration: { backend: "opt-0091-int8-weight-only-portable" },
+    });
+  });
+
+  it("keeps INT8 weights resident and FP32 accumulation in both shaders", () => {
+    expect(ACE_OPT_0091_DENSE_INT8_TILE_BYTES).toBe(8_704);
+    expect(ACE_OPT_0091_DENSE_INT8_TILE_WORDS).toBe(2_176);
+    for (const portable of [false, true]) {
+      const wgsl = aceOpt0091DenseInt8Wgsl(
+        { rows: 321, inner: 2_048, columns: 2_048 },
+        portable,
+      );
+      expect(wgsl).toContain("var<storage, read> weight: array<u32>");
+      expect(wgsl).toContain("fn unpack_i8x4(word: u32) -> vec4<f16>");
+      expect(wgsl).toContain("var acc0_0 = vec4<f32>(0.0)");
+      expect(wgsl).toContain("vec4<f32>(f32(a0)) * vec4<f32>(b0)");
+    }
+  });
+});
diff --git a/src/engines/musicgen-acestep/config.ts b/src/engines/musicgen-acestep/config.ts
index 9434301..8bfe80d 100644
--- a/src/engines/musicgen-acestep/config.ts
+++ b/src/engines/musicgen-acestep/config.ts
@@ -20,7 +20,7 @@ export const REFERENCE_PAYLOAD_PREFIX_SHA256 = "18f36c6420976475af65ecd833ca56c6
 export const DIRECT_REFERENCE_MANIFEST_SHA256 = "b44a3d157009d035a8f20aa752db4ceef2fac5bd140eff13be8f7488bc978089";
 export const DIRECT_REFERENCE_MANIFEST_REMOTE_NAME = `direct-manifest-${DIRECT_REFERENCE_MANIFEST_SHA256}.json`;
 export const DIT_MANIFEST_SHA256 = "d3fc0020efcf60702db411da2fd4b93e9bb84f1437ed310aef01c892727e452f";
-export const INT8_QUALITY_PREVIEW_DIT_MANIFEST_SHA256 = "ef8355b9cffff466b018b51275923982b071234933fe8a32897915eeeb01fa36";
+export const INT8_QUALITY_PREVIEW_DIT_MANIFEST_SHA256 = "a3233c9f97bc151b5ffa2a6cd8c9ecaee4e555497ee6fda20b70becaf7d55da1";
 export const VAE_MANIFEST_SHA256 = "36a54d79777d6826088095ba6ebc028fb4bea546368c0f0a29cd0eee8d656da7";
 
 export const ACE_DEMO_MODEL_VARIANTS = ["production", "int8-quality-preview"] as const;
@@ -38,11 +38,12 @@ export function aceProductionWorkerConfiguration() {
   return aceDemoWorkerConfiguration("production");
 }
 
-/** Select the approved production model or the full-size OPT-0089 listening preview. */
+/** Select the approved production model or the packed OPT-0091 INT8 preview. */
 export function aceDemoWorkerConfiguration(variant: AceDemoModelVariant) {
   const ditManifestSha256 = variant === "int8-quality-preview" ? INT8_QUALITY_PREVIEW_DIT_MANIFEST_SHA256 : DIT_MANIFEST_SHA256;
-  const ditPackage = variant === "int8-quality-preview" ? "dit-int8-fakequant" : "dit-revision7";
-  const localDitDirectory = variant === "int8-quality-preview" ? "files-fp16-dit-rev7-int8-fakequant" : "files-fp16-dit-rev7-oracle";
+  const ditPackage = variant === "int8-quality-preview" ? "dit-int8-packed" : "dit-revision7";
+  const localDitDirectory =
+    variant === "int8-quality-preview" ? `files-int8-dit-rev9/${INT8_QUALITY_PREVIEW_DIT_MANIFEST_SHA256}` : "files-fp16-dit-rev7-oracle";
   return {
     manifestUrl: productionManifestUrl("files-reference", "reference", REFERENCE_PAYLOAD_PREFIX_SHA256, DIRECT_REFERENCE_MANIFEST_REMOTE_NAME),
     manifestSha256: DIRECT_REFERENCE_MANIFEST_SHA256,
@@ -51,7 +52,7 @@ export function aceDemoWorkerConfiguration(variant: AceDemoModelVariant) {
     ditDensePackage: {
       manifestUrl: productionManifestUrl(localDitDirectory, ditPackage, ditManifestSha256),
       manifestSha256: ditManifestSha256,
-      runtimeProfile: "opt-0009-fp16-fp32-dense-v1",
+      runtimeProfile: variant === "int8-quality-preview" ? "opt-0091-int8-weight-only-v1" : "opt-0009-fp16-fp32-dense-v1",
     },
     ditAttentionRuntimeProfile: "opt-0070-fixed32-quad-query32-full-self-production-v1",
     vaePackage: {
diff --git a/src/engines/musicgen-acestep/model-download-progress.ts b/src/engines/musicgen-acestep/model-download-progress.ts
index 83e7ae3..ac55439 100644
--- a/src/engines/musicgen-acestep/model-download-progress.ts
+++ b/src/engines/musicgen-acestep/model-download-progress.ts
@@ -10,6 +10,9 @@ export const DEFERRED_VAE_CACHE_PHYSICAL_BYTES = 168_791_552;
 /** Complete physical footprint of a cold production-model cache. */
 export const MODEL_DOWNLOAD_TOTAL_BYTES = 5_747_730_175;
 
+/** Complete physical footprint when the packed INT8 DiT is selected. */
+export const INT8_MODEL_DOWNLOAD_TOTAL_BYTES = 4_426_524_415;
+
 /** Unique content-addressed payloads in the complete production-model cache. */
 export const MODEL_DOWNLOAD_ASSET_COUNT = 113;
 
@@ -29,6 +32,10 @@ export interface ModelDownloadProgress {
 
 export const INITIAL_MODEL_DOWNLOAD_PROGRESS: ModelDownloadProgress = createProgress(0);
 
+export function initialModelDownloadProgress(total = MODEL_DOWNLOAD_TOTAL_BYTES): ModelDownloadProgress {
+  return createProgress(0, total);
+}
+
 /** Show the first-download note until the complete pinned cache is present. */
 export function shouldShowModelDownloadNote(cache: ModelCacheSummary | undefined): boolean {
   return cache?.supported === true && !isModelDownloadComplete(cache);
@@ -50,9 +57,9 @@ export function isModelDownloadComplete(cache: ModelCacheSummary | undefined): b
  * `progress` payload. Unknown, malformed, and regressing events are ignored.
  */
 export function updateModelDownloadProgress(current: ModelDownloadProgress, event: unknown): ModelDownloadProgress {
-  const candidate = physicalCompletedBytes(event);
+  const candidate = physicalCompletedBytes(event, current.total);
   if (candidate === undefined || candidate <= current.completed) return current;
-  return createProgress(candidate);
+  return createProgress(candidate, current.total);
 }
 
 /** Format bytes with decimal units (1 GB = 1,000,000,000 bytes). */
@@ -68,7 +75,7 @@ export function formatModelDownloadAmount(progress: Pick<ModelDownloadProgress,
   return `${formatDecimalBytes(progress.completed)} / ${formatDecimalBytes(progress.total)}`;
 }
 
-function physicalCompletedBytes(event: unknown): number | undefined {
+function physicalCompletedBytes(event: unknown, totalBytes: number): number | undefined {
   const outer = record(event);
   if (outer === undefined) return undefined;
   const progress = record(outer.progress) ?? outer;
@@ -77,23 +84,27 @@ function physicalCompletedBytes(event: unknown): number | undefined {
     return initializationPhysicalBytes(progress);
   }
   if (progress.stage === "vae-load") {
-    return deferredVaePhysicalBytes(progress.message);
+    return deferredVaePhysicalBytes(progress.message, totalBytes);
   }
   return undefined;
 }
 
 function initializationPhysicalBytes(progress: Readonly<Record<string, unknown>>): number | undefined {
-  if (progress.unit !== "bytes" || progress.totalUnits !== INITIALIZATION_WEIGHTS_LOGICAL_BYTES) {
+  if (
+    progress.unit !== "bytes" ||
+    (progress.totalUnits !== INITIALIZATION_WEIGHTS_LOGICAL_BYTES &&
+      progress.totalUnits !== INT8_MODEL_DOWNLOAD_TOTAL_BYTES - DEFERRED_VAE_CACHE_PHYSICAL_BYTES)
+  ) {
     return undefined;
   }
 
-  const logicalCompleted = clampedByteCount(progress.completedUnits, INITIALIZATION_WEIGHTS_LOGICAL_BYTES);
+  const logicalCompleted = clampedByteCount(progress.completedUnits, progress.totalUnits);
   if (logicalCompleted === undefined) return undefined;
 
-  return Number((BigInt(logicalCompleted) * BigInt(INITIALIZATION_CACHE_PHYSICAL_BYTES)) / BigInt(INITIALIZATION_WEIGHTS_LOGICAL_BYTES));
+  return logicalCompleted;
 }
 
-function deferredVaePhysicalBytes(message: unknown): number | undefined {
+function deferredVaePhysicalBytes(message: unknown, totalBytes: number): number | undefined {
   if (typeof message !== "string") return undefined;
   const match = /(?:^|\s)([0-9]+)\/([0-9]+) bytes$/u.exec(message.trim());
   if (match === null) return undefined;
@@ -103,17 +114,17 @@ function deferredVaePhysicalBytes(message: unknown): number | undefined {
   if (total !== DEFERRED_VAE_CACHE_PHYSICAL_BYTES) return undefined;
   const vaeCompleted = clampedByteCount(completed, DEFERRED_VAE_CACHE_PHYSICAL_BYTES);
   if (vaeCompleted === undefined) return undefined;
-  return INITIALIZATION_CACHE_PHYSICAL_BYTES + vaeCompleted;
+  return totalBytes - DEFERRED_VAE_CACHE_PHYSICAL_BYTES + vaeCompleted;
 }
 
-function createProgress(completed: number): ModelDownloadProgress {
-  const safeCompleted = Math.min(MODEL_DOWNLOAD_TOTAL_BYTES, safeNonnegativeInteger(completed));
-  const fraction = safeCompleted / MODEL_DOWNLOAD_TOTAL_BYTES;
+function createProgress(completed: number, total = MODEL_DOWNLOAD_TOTAL_BYTES): ModelDownloadProgress {
+  const safeCompleted = Math.min(total, safeNonnegativeInteger(completed));
+  const fraction = safeCompleted / total;
   return Object.freeze({
     fraction,
     percentage: fraction * 100,
     completed: safeCompleted,
-    total: MODEL_DOWNLOAD_TOTAL_BYTES,
+    total,
   });
 }
 
diff --git a/src/music.ts b/src/music.ts
index 47e3a81..ed7d019 100644
--- a/src/music.ts
+++ b/src/music.ts
@@ -31,7 +31,9 @@ import {
   formatDecimalBytes,
   formatModelDownloadAmount,
   INITIAL_MODEL_DOWNLOAD_PROGRESS,
+  INT8_MODEL_DOWNLOAD_TOTAL_BYTES,
   MODEL_DOWNLOAD_TOTAL_BYTES,
+  initialModelDownloadProgress,
   updateModelDownloadProgress,
   type ModelDownloadProgress,
 } from "./engines/musicgen-acestep/model-download-progress.js";
@@ -61,10 +63,13 @@ const keyScaleInput = requiredElement<HTMLInputElement>("key-scale");
 const timeSignatureInput = requiredElement<HTMLInputElement>("time-signature");
 const vocalLanguageInput = requiredElement<HTMLInputElement>("vocal-language");
 const modelVariantSelect = requiredElement<HTMLSelectElement>("model-variant");
+const int8ModelOption = requiredElement<HTMLOptionElement>("int8-model-option");
+const int8ModelHint = requiredElement<HTMLElement>("int8-model-hint");
 const formError = requiredElement<HTMLParagraphElement>("form-error");
 const generateButton = requiredElement<HTMLButtonElement>("generate");
 const cancelButton = requiredElement<HTMLButtonElement>("cancel");
 const supportWarning = requiredElement<HTMLParagraphElement>("support-warning");
+const downloadNote = requiredElement<HTMLParagraphElement>("download-note");
 const progressPanel = requiredElement<HTMLElement>("progress-panel");
 const progressTitle = requiredElement<HTMLHeadingElement>("progress-title");
 const progressDetail = requiredElement<HTMLParagraphElement>("progress-detail");
@@ -174,6 +179,7 @@ function reportCrashBreadcrumb(): void {
 }
 
 configureTheme();
+configureExperimentalModels();
 wireEvents();
 reportCrashBreadcrumb();
 void initializePage();
@@ -183,6 +189,14 @@ function configureTheme(): void {
   applyTheme(theme);
 }
 
+function configureExperimentalModels(): void {
+  if (new URLSearchParams(location.search).get("int8") !== "1") return;
+  int8ModelOption.hidden = false;
+  int8ModelHint.hidden = false;
+  modelVariantSelect.value = "int8-quality-preview";
+  updateSelectedModelSize();
+}
+
 function applyTheme(theme: DemoTheme): void {
   document.documentElement.dataset.aceDemoTheme = theme;
   const dark = theme === "dark";
@@ -197,6 +211,7 @@ function applyTheme(theme: DemoTheme): void {
 }
 
 function wireEvents(): void {
+  modelVariantSelect.addEventListener("change", updateSelectedModelSize);
   githubProjectButton.addEventListener("click", () => {
     window.open(PROJECT_REPOSITORY_URL, "_blank", "noopener,noreferrer");
   });
@@ -267,6 +282,16 @@ function wireEvents(): void {
   });
 }
 
+function selectedModelDownloadBytes(): number {
+  return selectedModelVariant() === "int8-quality-preview" ? INT8_MODEL_DOWNLOAD_TOTAL_BYTES : MODEL_DOWNLOAD_TOTAL_BYTES;
+}
+
+function updateSelectedModelSize(): void {
+  downloadNote.innerHTML = `The first generation downloads <strong>${formatDecimalBytes(
+    selectedModelDownloadBytes(),
+  )}</strong>, then caches the model for later visits.`;
+}
+
 function queueProjectTooltip(event: PointerEvent): void {
   pendingTooltipPoint = { clientX: event.clientX };
   if (tooltipRenderFrame !== undefined) return;
@@ -396,7 +421,9 @@ async function beginGeneration(): Promise<void> {
   generationDetails = undefined;
   diagnosticDetails = [];
   fatalGpuDiagnostic = false;
-  modelProgress = INITIAL_MODEL_DOWNLOAD_PROGRESS;
+  modelProgress = initialModelDownloadProgress(
+    selectedModelVariant() === "int8-quality-preview" ? INT8_MODEL_DOWNLOAD_TOTAL_BYTES : MODEL_DOWNLOAD_TOTAL_BYTES,
+  );
   coldDownload = false;
   setBusy(true);
   resultPanel.hidden = true;
@@ -699,7 +726,7 @@ async function publishResult(result: AceGenerationResult): Promise<void> {
       modelManifestSha256: result.modelManifestSha256,
       metrics: result.metrics,
     };
-    summaryModel.textContent = workerModelVariant === "int8-quality-preview" ? "INT8 quality preview" : "Production";
+    summaryModel.textContent = workerModelVariant === "int8-quality-preview" ? "Compressed INT8 preview" : "Production";
     modelProgress = updateModelDownloadProgress(modelProgress, {
       stage: "vae-load",
       message: "network: complete 168791552/168791552 bytes",
@@ -899,7 +926,7 @@ async function refreshCacheInfo(): Promise<void> {
     if (!cacheDetails.supported) {
       cacheStatus.textContent = "Model storage is unavailable in this context.";
     } else if (cacheDetails.assetCount === 0 && cacheDetails.partialAssetCount === 0) {
-      cacheStatus.textContent = `Not downloaded · ${formatDecimalBytes(MODEL_DOWNLOAD_TOTAL_BYTES)} on first generation`;
+      cacheStatus.textContent = `Not downloaded · ${formatDecimalBytes(selectedModelDownloadBytes())} on first generation`;
     } else {
       const partial = cacheDetails.partialAssetCount === 0 ? "" : ` · ${cacheDetails.partialAssetCount} incomplete`;
       const persistence = cacheDetails.persisted ? "persistent browser storage" : "browser-managed storage";
@@ -923,7 +950,7 @@ async function deleteDownloadedModel(): Promise<void> {
     await disposeWorker();
     cacheStatus.textContent = "Deleting downloaded model…";
     await deleteAceDemoModelCache();
-    modelProgress = INITIAL_MODEL_DOWNLOAD_PROGRESS;
+    modelProgress = initialModelDownloadProgress(selectedModelDownloadBytes());
     await refreshCacheInfo();
   } catch (error) {
     cacheStatus.textContent = `Could not delete the model: ${errorMessage(error)}`;
diff --git a/test/music-model-download-progress.test.ts b/test/music-model-download-progress.test.ts
new file mode 100644
index 0000000..7472db4
--- /dev/null
+++ b/test/music-model-download-progress.test.ts
@@ -0,0 +1,35 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  DEFERRED_VAE_CACHE_PHYSICAL_BYTES,
+  INT8_MODEL_DOWNLOAD_TOTAL_BYTES,
+  initialModelDownloadProgress,
+  updateModelDownloadProgress,
+} from "../src/engines/musicgen-acestep/model-download-progress.js";
+
+describe("music model download progress", () => {
+  it("tracks the packed INT8 total through initialization and deferred VAE", () => {
+    const initializationBytes = INT8_MODEL_DOWNLOAD_TOTAL_BYTES - DEFERRED_VAE_CACHE_PHYSICAL_BYTES;
+    const initial = initialModelDownloadProgress(INT8_MODEL_DOWNLOAD_TOTAL_BYTES);
+    const initialized = updateModelDownloadProgress(initial, {
+      stage: "weights",
+      unit: "bytes",
+      completedUnits: initializationBytes,
+      totalUnits: initializationBytes,
+    });
+    expect(initialized).toMatchObject({
+      completed: initializationBytes,
+      total: INT8_MODEL_DOWNLOAD_TOTAL_BYTES,
+    });
+
+    const complete = updateModelDownloadProgress(initialized, {
+      stage: "vae-load",
+      message: `network: complete ${DEFERRED_VAE_CACHE_PHYSICAL_BYTES}/${DEFERRED_VAE_CACHE_PHYSICAL_BYTES} bytes`,
+    });
+    expect(complete).toMatchObject({
+      completed: INT8_MODEL_DOWNLOAD_TOTAL_BYTES,
+      total: INT8_MODEL_DOWNLOAD_TOTAL_BYTES,
+      fraction: 1,
+    });
+  });
+});
diff --git a/test/music-model-variant.test.ts b/test/music-model-variant.test.ts
index 1add0e6..7db6796 100644
--- a/test/music-model-variant.test.ts
+++ b/test/music-model-variant.test.ts
@@ -18,19 +18,29 @@ describe("music model variants", () => {
       ...production,
       ditDensePackage: {
         ...production.ditDensePackage,
-        manifestUrl: `https://huggingface.co/FluidInference/ace-step-webgpu-models/resolve/main/v1/dit-int8-fakequant/${INT8_QUALITY_PREVIEW_DIT_MANIFEST_SHA256}/manifest.json`,
+        manifestUrl: `https://huggingface.co/FluidInference/ace-step-webgpu-models/resolve/main/v1/dit-int8-packed/${INT8_QUALITY_PREVIEW_DIT_MANIFEST_SHA256}/manifest.json`,
         manifestSha256: INT8_QUALITY_PREVIEW_DIT_MANIFEST_SHA256,
+        runtimeProfile: "opt-0091-int8-weight-only-v1",
       },
     });
   });
 
-  it("labels the preview as experimental and full-size", () => {
+  it("labels the preview with its measured packed size", () => {
     const html = readFileSync(new URL("../music.html", import.meta.url), "utf8");
 
     expect(html).toContain("Production (recommended)");
-    expect(html).toContain("INT8 quality preview (experimental)");
-    expect(html).toContain("preview tests audible quantization effects but is not compressed");
-    expect(html).toContain("separate 3.02 GB DiT download");
+    expect(html).toContain("Compressed INT8 preview (experimental)");
+    expect(html).toMatch(/id="int8-model-option"[^>]+hidden/);
+    expect(html).toMatch(/id="int8-model-hint" hidden/);
+    expect(html).toContain("1.70 GB packed INT8 DiT");
+    expect(html).toContain("43.7% smaller");
     expect(html).toMatch(/option value="production" selected/);
   });
+
+  it("preselects the compressed model only for the private verification URL", () => {
+    const source = readFileSync(new URL("../src/music.ts", import.meta.url), "utf8");
+
+    expect(source).toContain('new URLSearchParams(location.search).get("int8") !== "1"');
+    expect(source).toContain('modelVariantSelect.value = "int8-quality-preview"');
+  });
 });
diff --git a/test/music-preparation.test.ts b/test/music-preparation.test.ts
index 07a12ac..88a55d8 100644
--- a/test/music-preparation.test.ts
+++ b/test/music-preparation.test.ts
@@ -36,6 +36,9 @@ function page() {
     initializationRequestId: undefined,
     activeJobId: undefined,
     INITIAL_MODEL_DOWNLOAD_PROGRESS: {},
+    INT8_MODEL_DOWNLOAD_TOTAL_BYTES: 4_426_524_415,
+    MODEL_DOWNLOAD_TOTAL_BYTES: 5_747_730_175,
+    initialModelDownloadProgress: (total: number) => ({ total }),
     isModelDownloadComplete: () => true,
     cacheDetails: undefined,
     requestAceModelStoragePersistence: async () => false,