v0.8.1:1 - fix disk probe: $HOME wasn't expanding inside shlex.quote

The 0.8.1:0 probe wrapped the entire path (including $HOME) in
shlex.quote, which produces single quotes — preventing shell
variable expansion. The resulting `[ -d '$HOME/.cache/...' ]` test
looked for a literal path starting with the string $HOME and
always failed, so every model reported as "not downloaded" and no
trash icons rendered.

Fix: embed $HOME in a double-quoted shell context (which allows
expansion) and validate the cache dirname against a whitelist
[A-Za-z0-9._-]+ rather than relying on shlex quoting. The dirname
is fully constrained by HF's naming rules + our org--name munging,
so the whitelist is tight enough.

Verified against Spark 1: probe now correctly reports the
25,075,981,924 bytes (23.4 GB) of Qwen3.6's cache dir.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

image/app/disk.py

@@ -10,7 +10,7 @@ model or one tied to an in-flight swap/download.
 """
 from __future__ import annotations
 import asyncio
-import shlex
+import re
 from dataclasses import dataclass
 from typing import Optional
 
@@ -18,17 +18,21 @@ from .config import Settings
 from .ssh import ssh_run
 
 
+# HF cache dirnames are `models--<org>--<name>` where <org> and <name> only contain
+# Hugging Face's allowed identifier chars: letters, digits, dot, dash, underscore.
+# Validate against this whitelist so we can safely embed the dirname into a shell
+# command without quoting (we need $HOME outside the quotes to expand).
+_SAFE_DIRNAME = re.compile(r"^[A-Za-z0-9._\-]+$")
+
+
 def repo_to_cache_dirname(repo: str) -> str:
     """Convert 'org/name' to 'models--org--name' (the HF hub cache directory)."""
     if "/" not in repo:
         raise ValueError(f"repo must be in 'org/name' form: {repo!r}")
-    return "models--" + repo.replace("/", "--")
-
-
-def _cache_path(repo: str) -> str:
-    """Full remote path to the model's cache directory."""
-    # Use $HOME so it resolves correctly regardless of the SSH user's home.
-    return f"$HOME/.cache/huggingface/hub/{repo_to_cache_dirname(repo)}"
+    dn = "models--" + repo.replace("/", "--")
+    if not _SAFE_DIRNAME.fullmatch(dn):
+        raise ValueError(f"unsafe cache dirname (rejected by whitelist): {dn!r}")
+    return dn
 
 
 @dataclass
@@ -51,13 +55,13 @@ async def probe_host(host: str, user: str, repo: str, settings: Settings) -> Hos
     """Return whether the model's cache dir exists on this host and its size."""
     if not host or not user:
         return HostDiskResult(host=host or "?", on_disk=False, error="host not configured")
-    path = _cache_path(repo)
-    # `du -sb` prints bytes; if the dir doesn't exist, `du` returns non-zero.
-    # We test existence explicitly first so we can report on_disk=False cleanly.
+    dn = repo_to_cache_dirname(repo)  # whitelisted; safe to embed
+    # $HOME must expand server-side, so we build the path with double quotes
+    # (which DO allow variable expansion) rather than shlex.quote single quotes.
     cmd = (
-        f"if [ -d {shlex.quote(path)} ]; then "
-        f"du -sb {shlex.quote(path)} 2>/dev/null | awk '{{print $1}}'; "
-        f"else echo MISSING; fi"
+        f'P="$HOME/.cache/huggingface/hub/{dn}"; '
+        f'if [ -d "$P" ]; then du -sb "$P" 2>/dev/null | cut -f1; '
+        f'else echo MISSING; fi'
     )
     rc, out, err = await ssh_run(host, user, cmd, settings, timeout=20.0)
     if rc != 0:
@@ -88,19 +92,19 @@ async def delete_host(host: str, user: str, repo: str, settings: Settings) -> Ho
     """Probe + rm -rf on one host. Returns bytes freed (0 if the dir wasn't there)."""
     if not host or not user:
         return HostDiskResult(host=host or "?", on_disk=False, error="host not configured")
-    path = _cache_path(repo)
-    # Safety: hard-code the prefix in the command so a bad `repo` can never escape.
+    dn = repo_to_cache_dirname(repo)  # whitelisted; safe to embed
     # Compute size first, then remove. If absent, still return success (idempotent).
+    # $HOME is in double-quoted context so it expands; the dirname is whitelisted.
     cmd = (
-        f"set -e; "
-        f"P={shlex.quote(path)}; "
-        f"if [ -d \"$P\" ]; then "
-        f"  SIZE=$(du -sb \"$P\" 2>/dev/null | awk '{{print $1}}'); "
-        f"  rm -rf -- \"$P\"; "
-        f"  echo FREED $SIZE; "
-        f"else "
-        f"  echo FREED 0; "
-        f"fi"
+        f'set -e; '
+        f'P="$HOME/.cache/huggingface/hub/{dn}"; '
+        f'if [ -d "$P" ]; then '
+        f'  SIZE=$(du -sb "$P" 2>/dev/null | cut -f1); '
+        f'  rm -rf -- "$P"; '
+        f'  echo "FREED $SIZE"; '
+        f'else '
+        f'  echo "FREED 0"; '
+        f'fi'
     )
     rc, out, err = await ssh_run(host, user, cmd, settings, timeout=120.0)
     if rc != 0: