Merge remote-tracking branch 'origin/main' into windows-torch-211

Reconcile PR #7256 (Windows torch 2.11 + release preservation, installer
comment reduction, torch 2.11 default line) with 77 commits of main install
rewrites. Base is main's newer install semantics; this branch's still-novel
contributions are layered on top.

Key decisions:
- install.ps1: kept main's rollback lifecycle (try/finally Restore-StudioVenvRollback,
  #7342) and the installed-version report (#7265); layered this branch's torch-2.11
  allowance (torch<2.12.0 on the Windows CUDA fresh-install, CPU fallback and flavor
  repairs), the release-preservation port (Get-InstalledTorchVersionRaw / kept-release
  installs / UNSLOTH_KEPT_TORCH handoff / torch-overrides freeze) and the Exit-InstallFailure
  UNSLOTH_KEPT_TORCH clear.
- install.sh: took main's newer AMD/Strix routing (per-arch index reroute #7264/#7300,
  runtime-less gfx inference #7305, KFD detection fix #7314, Radeon 8065S regex #7290,
  signal-restore trap #7342) and the #7365 unsloth pin bump; kept this branch's
  _TORCH_CEILING/_TORCHVISION_CEILING/_TORCHAUDIO_CEILING refactor widening the default
  ceiling to torch<2.12.0.
- studio/install_python_stack.py: deferred all five code conflicts to main's Strix
  inference logic (result is AST-identical to main; only comment reductions remain).
- studio/setup.ps1: took main's comment covering the whisper.cpp dictation markers
  (#7095); the UNSLOTH_KEPT_TORCH consumption handoff auto-merged intact.

Dropped as superseded by main: this branch's stale unsloth>=2026.7.4 pins (main #7365),
the older rocm7.1->rocm7.2 Strix reroute (main #7264/#7300), the narrow Radeon 80[0-9]0S
regex (main #7290), and the pre-inference has_hip_torch gate (main's rocm_torch_ready gate,
Codex P1 #7305). The two review-item fixes (grep -E in test_torch_constraint.sh,
UNSLOTH_KEPT_TORCH clear in Exit-InstallFailure) survive.

tests/python/test_torchcodec_torch_compat.py

@@ -0,0 +1,129 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+
+"""torch / torchcodec ABI guardrails (unslothai/unsloth#7225)."""
+
+from __future__ import annotations
+
+import importlib.util
+import re
+import sys
+import types
+from pathlib import Path
+
+
+REPO_ROOT = Path(__file__).resolve().parents[2]
+PYPROJECT = REPO_ROOT / "pyproject.toml"
+IMPORT_FIXES_PATH = REPO_ROOT / "unsloth" / "import_fixes.py"
+
+
+def _load_import_fixes_module():
+    spec = importlib.util.spec_from_file_location(
+        "unsloth_import_fixes_under_test",
+        IMPORT_FIXES_PATH,
+    )
+    assert spec and spec.loader
+    mod = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(mod)
+    return mod
+
+
+def test_pyproject_declares_torch210_audio_extra_with_python_gate():
+    text = PYPROJECT.read_text(encoding = "utf-8")
+    assert "audio-torch210 = [" in text
+    assert "torchcodec>=0.10.0,<0.11.0" in text
+    assert "python_version >= '3.10'" in text
+    assert "audio-torch290 = [" in text
+    assert "audio-torch280 = [" in text
+    assert "\naudio = [" not in text
+
+
+def _stub_torch(monkeypatch, version: str):
+    torch_mod = types.ModuleType("torch")
+    torch_mod.__version__ = version
+    monkeypatch.setitem(sys.modules, "torch", torch_mod)
+
+
+def test_torch210_extras_bundle_audio_torch210():
+    text = PYPROJECT.read_text(encoding = "utf-8")
+    for extra in (
+        "cu128-torch2100",
+        "cu126-ampere-torch2100",
+        "rocm72-torch2100",
+    ):
+        match = re.search(rf"^{extra} = \[(.*?)^\]", text, re.MULTILINE | re.DOTALL)
+        assert match is not None, extra
+        assert "unsloth[audio-torch210]" in match.group(1)
+
+
+def test_torchcodec_matrix_matches_notebook_validator():
+    from scripts import notebook_validator as nv
+    fixes = _load_import_fixes_module()
+    assert fixes._TORCH_TORCHCODEC_MINORS == nv.TORCH_TORCHCODEC
+
+
+def test_torchcodec_exclusive_upper_bound():
+    fixes = _load_import_fixes_module()
+    assert fixes._torchcodec_exclusive_upper("0.10") == "<0.11.0"
+    assert fixes._torchcodec_exclusive_upper("0.9") == "<0.10.0"
+
+
+def test_torch290_rejects_torchcodec_07(monkeypatch):
+    import importlib.metadata
+
+    fixes = _load_import_fixes_module()
+    _stub_torch(monkeypatch, "2.9.0+cu128")
+    monkeypatch.setattr(importlib.metadata, "version", lambda _name: "0.7.0")
+
+    hint = fixes._torchcodec_version_mismatch_hint()
+    assert hint is not None
+    assert "audio-torch210" not in hint
+
+
+def test_torch280_accepts_torchcodec_07(monkeypatch):
+    import importlib.metadata
+
+    fixes = _load_import_fixes_module()
+    _stub_torch(monkeypatch, "2.8.0+cu128")
+    monkeypatch.setattr(importlib.metadata, "version", lambda _name: "0.7.0")
+
+    assert fixes._torchcodec_version_mismatch_hint() is None
+
+
+def test_torch210_rejects_torchcodec_011(monkeypatch):
+    import importlib.metadata
+
+    fixes = _load_import_fixes_module()
+    _stub_torch(monkeypatch, "2.10.0+cu128")
+    monkeypatch.setattr(
+        importlib.metadata,
+        "version",
+        lambda _name: "0.11.0",
+    )
+
+    hint = fixes._torchcodec_version_mismatch_hint()
+    assert hint is not None
+    assert "torchcodec 0.11.0" in hint
+    assert "audio-torch210" in hint
+    assert "<0.11.0" in hint
+    assert "<11.0" not in hint
+
+
+def test_torch210_accepts_torchcodec_010(monkeypatch):
+    import importlib.metadata
+
+    fixes = _load_import_fixes_module()
+    _stub_torch(monkeypatch, "2.10.0+cu128")
+    monkeypatch.setattr(
+        importlib.metadata,
+        "version",
+        lambda _name: "0.10.0+cu128",
+    )
+
+    assert fixes._torchcodec_version_mismatch_hint() is None
+
+
+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)