Studio: self-heal a pre-#6483-fix anyio>=4.14 stuck in existing installs (#6805)

* Studio: self-heal a pre-#6483-fix anyio>=4.14 stuck in existing installs

The <4.14 cap in constraints.txt/no-torch-runtime.txt only constrains new
anyio resolutions. An install made before that cap existed can already be
sitting on anyio 4.14+, and since it already satisfies mcp/fastmcp's
anyio>=4.5 floor, every later constrained install skips it as
already-satisfied -- so affected installs never recover and keep hitting
the cancel-scope RuntimeError on every request (#6797, a recurrence of
#6483). Force-reinstall anyio<4.14 whenever a stuck 4.14+ is detected.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Studio: also repair anyio on the update fast path

setup.sh's _SKIP_PYTHON_DEPS and setup.ps1's $SkipPythonDeps skip
install_python_stack.py entirely once the installed package version already
matches PyPI latest, so an install stuck on anyio>=4.14 with an otherwise
up-to-date package never reaches the repair added in install_python_stack.py.
Probe anyio on that fast path too and fall through to the full dependency
pass when it's still >=4.14, mirroring the existing ROCm/CPU-torch override
right below it.

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

studio/install_python_stack.py

@@ -181,6 +181,41 @@ def _probe_installed_torch_version() -> str | None:
     return lines[-1] if lines else None
 
 
+# constraints.txt caps new anyio resolutions at <4.14 (#6483), but an install
+# from before the cap existed can already be stuck at 4.14+, which later
+# constrained installs won't touch since it already satisfies mcp/fastmcp.
+_ANYIO_BAD_FLOOR = (4, 14)
+
+
+def _installed_anyio_version() -> tuple[int, int] | None:
+    try:
+        from importlib.metadata import version as _pkg_version
+        raw = _pkg_version("anyio")
+    except Exception:
+        return None
+    parts = raw.split(".")
+    try:
+        major = int(parts[0])
+        minor = int(re.sub(r"[^0-9].*", "", parts[1])) if len(parts) > 1 else 0
+    except (IndexError, ValueError):
+        return None
+    return (major, minor)
+
+
+def _repair_bad_anyio() -> None:
+    installed = _installed_anyio_version()
+    if installed is None or installed < _ANYIO_BAD_FLOOR:
+        return
+    _safe_print(_dim(f"   anyio {installed[0]}.{installed[1]} found -- reinstalling anyio<4.14..."))
+    pip_install(
+        "Repairing anyio version",
+        "--no-cache-dir",
+        "--force-reinstall",
+        "anyio<4.14.0",
+        constrain = False,
+    )
+
+
 # AMD Windows ROCm wheels (repo.amd.com/rocm/whl/{arch_family}/).
 # Override with UNSLOTH_ROCM_WINDOWS_MIRROR for air-gapped/mirror installs.
 _ROCM_WINDOWS_INDEX_BASE = (
@@ -1970,7 +2005,7 @@ def install_python_stack() -> int:
     package_name = os.environ.get("STUDIO_PACKAGE_NAME", "unsloth")
     # --local overlays a local repo checkout after updating deps.
     local_repo = os.environ.get("STUDIO_LOCAL_REPO", "")
-    base_total = 10 if IS_WINDOWS else 11
+    base_total = 11 if IS_WINDOWS else 12  # +1 for the anyio repair check (step 8b)
     if IS_MACOS:
         base_total -= 1  # triton step is skipped on macOS
     if not IS_MACOS and not NO_TORCH:
@@ -2284,6 +2319,10 @@ def install_python_stack() -> int:
         req = REQ_ROOT / "studio.txt",
     )
 
+    # 8b. anyio repair (#6483)
+    _progress("anyio check")
+    _repair_bad_anyio()
+
     # 9. Data-designer dependencies
     _progress("data designer deps")
     pip_install(