diff --git a/install.sh b/install.sh
index fc9aa0a431..166beeb52c 100755
--- a/install.sh
+++ b/install.sh
@@ -19,6 +19,17 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 # Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
 set -e
+# ── Why the installer lives in a function ──
+# Under `curl ... | sh`, sh is the pipe READER. This file is ~150KB, so a top-level
+# `exit` left most of it unread, the write end failed, and curl tacked
+# "(56) Failure writing output to destination" onto our own error message. Wrapping
+# the body forces sh to parse to the closing brace first, so the pipe always drains
+# (install.ps1 has always had this shape).
+#
+# Body is deliberately NOT reindented: reflowing 4000+ lines would bury the change,
+# and `exit` still exits the shell from inside a function. Do not add
+# `exec < /dev/null`: for a piped shell that closes the script's own source.
+_unsloth_main() {
 
 # ── Output style (aligned with studio/setup.sh) ──
 RULE=""
@@ -4447,3 +4458,8 @@ else
     substep "(add -H 0.0.0.0 --cloudflare for a public Cloudflare HTTPS link, or --secure to keep the raw port private; anyone with the API key can run code)"
     echo ""
 fi
+
+}
+
+# Every byte above is parsed before this line runs, which is the point.
+_unsloth_main "$@"
diff --git a/pyproject.toml b/pyproject.toml
index 7359a51fa6..ce19d21399 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -128,14 +128,19 @@ huggingfacenotorch = [
 ]
 # torchcodec backend for Gemma audio / datasets>=4 (#7225).
 # Pick the audio-torch* pin matching your torch minor (see TORCH_TORCHCODEC).
+# torchcodec publishes no sdist and only manylinux_2_28_x86_64, macosx_*_arm64
+# and win_amd64 wheels, so Linux aarch64, Windows ARM64 and Intel Mac have
+# nothing to resolve and pip fails the whole install rather than skipping audio.
+# Gate on the platforms that have a wheel, matching
+# PLATFORM_LACKS_TORCHCODEC_WHEEL in studio/install_python_stack.py.
 audio-torch210 = [
-    "torchcodec>=0.10.0,<0.11.0 ; python_version >= '3.10'",
+    "torchcodec>=0.10.0,<0.11.0 ; python_version >= '3.10' and (((sys_platform == 'linux' or sys_platform == 'win32') and (platform_machine == 'x86_64' or platform_machine == 'AMD64')) or (sys_platform == 'darwin' and platform_machine == 'arm64'))",
 ]
 audio-torch290 = [
-    "torchcodec>=0.8.0,<0.10.0 ; python_version >= '3.10'",
+    "torchcodec>=0.8.0,<0.10.0 ; python_version >= '3.10' and (((sys_platform == 'linux' or sys_platform == 'win32') and (platform_machine == 'x86_64' or platform_machine == 'AMD64')) or (sys_platform == 'darwin' and platform_machine == 'arm64'))",
 ]
 audio-torch280 = [
-    "torchcodec>=0.6.0,<0.8.0 ; python_version >= '3.9'",
+    "torchcodec>=0.6.0,<0.8.0 ; python_version >= '3.9' and (((sys_platform == 'linux' or sys_platform == 'win32') and (platform_machine == 'x86_64' or platform_machine == 'AMD64')) or (sys_platform == 'darwin' and platform_machine == 'arm64'))",
 ]
 huggingface = [
     "unsloth[huggingfacenotorch]",
diff --git a/tests/python/test_torchcodec_torch_compat.py b/tests/python/test_torchcodec_torch_compat.py
index 6ad16a73f4..728a51a321 100644
--- a/tests/python/test_torchcodec_torch_compat.py
+++ b/tests/python/test_torchcodec_torch_compat.py
@@ -11,12 +11,21 @@ import sys
 import types
 from pathlib import Path
 
+import pytest
+
 
 REPO_ROOT = Path(__file__).resolve().parents[2]
 PYPROJECT = REPO_ROOT / "pyproject.toml"
 IMPORT_FIXES_PATH = REPO_ROOT / "unsloth" / "import_fixes.py"
 
 
+def _tomllib():
+    if sys.version_info >= (3, 11):
+        import tomllib
+        return tomllib
+    return pytest.importorskip("tomli")
+
+
 def _load_import_fixes_module():
     spec = importlib.util.spec_from_file_location(
         "unsloth_import_fixes_under_test",
@@ -127,3 +136,41 @@ def test_import_fixes_loads_on_python39_syntax():
     """Regression: module must import on 3.9 (postponed annotations for str | None)."""
     fixes = _load_import_fixes_module()
     assert callable(fixes._torchcodec_version_mismatch_hint)
+
+
+def test_audio_extras_are_gated_to_platforms_with_a_torchcodec_wheel():
+    """torchcodec publishes no sdist and no wheel for Linux aarch64, Windows ARM64 or
+    Intel Mac, so an ungated pin makes pip fail the whole install on those hosts instead
+    of just skipping audio -- and the cu*/rocm*/intel torch 2.10 extras pull it in.
+    The marker must match PLATFORM_LACKS_TORCHCODEC_WHEEL in install_python_stack.py.
+    """
+    markers = pytest.importorskip("packaging.markers")
+    tomllib = _tomllib()
+    extras = tomllib.loads(PYPROJECT.read_text(encoding = "utf-8"))["project"][
+        "optional-dependencies"
+    ]
+    audio = {n: d for n, d in extras.items() if n.startswith("audio-torch")}
+    assert audio, "expected audio-torch* extras"
+
+    supported = [
+        {"sys_platform": "linux", "platform_machine": "x86_64"},
+        {"sys_platform": "win32", "platform_machine": "AMD64"},
+        {"sys_platform": "darwin", "platform_machine": "arm64"},
+    ]
+    unsupported = [
+        {"sys_platform": "linux", "platform_machine": "aarch64"},
+        {"sys_platform": "win32", "platform_machine": "ARM64"},
+        {"sys_platform": "darwin", "platform_machine": "x86_64"},
+    ]
+    for name, deps in audio.items():
+        for dep in deps:
+            _, _, marker_text = dep.partition(";")
+            assert marker_text.strip(), f"{name}: {dep!r} has no marker"
+            marker = markers.Marker(marker_text.strip())
+            env = {"python_version": "3.12"}
+            for case in supported:
+                assert marker.evaluate({**env, **case}), f"{name} must install on {case}"
+            for case in unsupported:
+                assert not marker.evaluate(
+                    {**env, **case}
+                ), f"{name} has no wheel for {case} and must not be resolved there"
diff --git a/tests/sh/test_install_pipe_safety.sh b/tests/sh/test_install_pipe_safety.sh
new file mode 100755
index 0000000000..be479dd5a5
--- /dev/null
+++ b/tests/sh/test_install_pipe_safety.sh
@@ -0,0 +1,89 @@
+#!/bin/bash
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
+#
+# Guards that `curl ... | sh` cannot report a bogus transport error.
+#
+# History: install.sh was ~150KB of top-level statements. A top-level `exit` left most
+# of the file unread, the write end failed, and curl appended "(56) Failure writing
+# output to destination" (or "(23) Failed writing body") after our own error message,
+# so users read a real diagnosis as a broken download. The fix is structural: the body
+# lives in _unsloth_main, so sh parses the whole file before running anything.
+#
+# This pins both halves of that contract: the writer must not be killed, AND the
+# installer's own exit code must still reach the caller.
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+INSTALL_SH="$SCRIPT_DIR/../../install.sh"
+PASS=0
+FAIL=0
+
+assert_eq() {
+    _label="$1"; _expected="$2"; _actual="$3"
+    if [ "$_actual" = "$_expected" ]; then
+        echo "  PASS: $_label"
+        PASS=$((PASS + 1))
+    else
+        echo "  FAIL: $_label (expected '$_expected', got '$_actual')"
+        FAIL=$((FAIL + 1))
+    fi
+}
+
+echo "=== structure ==="
+
+# The wrapper must be invoked on the LAST executable line, or sh starts executing
+# before it has drained the pipe.
+if grep -q '^_unsloth_main() {' "$INSTALL_SH"; then
+    echo "  PASS: _unsloth_main is defined at top level"
+    PASS=$((PASS + 1))
+else
+    echo "  FAIL: install.sh is not wrapped in _unsloth_main -- curl-pipe safety is gone"
+    FAIL=$((FAIL + 1))
+fi
+
+_last="$(grep -vE '^\s*(#|$)' "$INSTALL_SH" | tail -1)"
+assert_eq "last statement invokes the wrapper" '_unsloth_main "$@"' "$_last"
+
+# Below one pipe buffer the file would fit in the kernel's buffer and this test would
+# prove nothing, so fail loudly instead of passing vacuously.
+_bytes="$(wc -c < "$INSTALL_SH" | tr -d ' ')"
+if [ "$_bytes" -gt 65536 ]; then
+    echo "  PASS: install.sh ($_bytes bytes) exceeds a 64KiB pipe buffer, so this matters"
+    PASS=$((PASS + 1))
+else
+    echo "  FAIL: install.sh is only $_bytes bytes; re-derive whether pipe safety still applies"
+    FAIL=$((FAIL + 1))
+fi
+
+echo "=== behaviour: an early exit must not kill the writer ==="
+
+# `--python` with no argument exits 1 from argument validation having done no work: no
+# venv, no downloads, no filesystem writes. Deterministic and safe to run for real.
+#
+# PIPESTATUS must be read on the very next line, so drop errexit around the pipeline
+# rather than appending `|| true`, which would clobber it with the status of `true`.
+set +e
+cat "$INSTALL_SH" | sh -s -- --python >/dev/null 2>&1
+_pipe=("${PIPESTATUS[@]}")
+set -e
+_writer_rc="${_pipe[0]}"
+_reader_rc="${_pipe[1]}"
+
+# A writer rc of 141 (128 + SIGPIPE) is the failure mode curl reports as (56)/(23).
+assert_eq "writer survives the early exit (not SIGPIPE)" "0" "$_writer_rc"
+assert_eq "installer's own exit code still propagates" "1" "$_reader_rc"
+
+echo "=== behaviour: the same holds for a mid-file exit ==="
+# `--package '-evil'` exits from a later validation block, still before any filesystem
+# work, so the property is not specific to one early branch.
+set +e
+cat "$INSTALL_SH" | sh -s -- --package '-evil' >/dev/null 2>&1
+_pipe2=("${PIPESTATUS[@]}")
+set -e
+assert_eq "writer survives a later exit" "0" "${_pipe2[0]}"
+assert_eq "later exit code propagates" "1" "${_pipe2[1]}"
+
+echo ""
+echo "=== $PASS passed, $FAIL failed ==="
+[ "$FAIL" -eq 0 ] || exit 1