fix(audit): --diff flag, anyio dep, README example, unused_mut warn

Author: nikolay-e

README.md

@@ -179,12 +179,16 @@ text_str = to_text(tree)
 md_str = to_markdown(tree)
 
 # Diff context mode
-from treemapper import build_diff_context
+from pathlib import Path
+from treemapper import build_diff_context, to_yaml
 
 ctx = build_diff_context(
-    root_dir,                 # Path to repository root
-    diff_range,               # e.g. "HEAD~1..HEAD", "main..feature"
-    budget_tokens=None,       # token limit (None = convergence-based)
+    Path("."),                # repository root
+    "HEAD~1..HEAD",           # diff range; also accepts "main..feature"
+    budget_tokens=None,       # None = convergence-based (default)
+                              #   0  = diff only, no expansion (recall floor)
+                              #  <0  = unlimited (10M-token soft ceiling)
+                              #  >0  = explicit token cap
     alpha=0.6,                # PPR damping factor
     tau=0.08,                 # stopping threshold
     full=False,               # skip smart selection

diffctx/src/main.rs

@@ -23,7 +23,7 @@ struct Cli {
     #[arg(long, default_value = "yaml")]
     format: String,
 
-    #[arg(long)]
+    #[arg(long = "diff")]
     diff_ref: Option<String>,
 
     #[arg(long, default_value_t = DEFAULT_PPR_ALPHA)]

diffctx/src/parsers/tree_sitter_strategy.rs

@@ -977,6 +977,7 @@ fn find_lang_config(path: &str) -> Option<&'static LangConfig> {
 }
 
 static LANGUAGE_CACHE: Lazy<FxHashMap<&'static str, Language>> = Lazy::new(|| {
+    #[allow(unused_mut)]
     let mut m: FxHashMap<&'static str, Language> = FxHashMap::default();
 
     #[cfg(feature = "tree-sitter-python")]

pyproject.toml

@@ -102,6 +102,7 @@ optional-dependencies.full = [
   "treemapper[tree-sitter]",
 ]
 optional-dependencies.mcp = [
+  "anyio>=4.5,<5.0",
   "mcp>=1.27,<2.0",
 ]
 optional-dependencies.nlp = [