fix(docs, xtask): repair cross-book links and harden local serve

csharp-book/src/ch13-concurrency.md

@@ -6,7 +6,7 @@
 >
 > **Difficulty:** 🔴 Advanced
 
-> **Deep dive**: For production async patterns (stream processing, graceful shutdown, connection pooling, cancellation safety), see the companion [Async Rust Training](../../source-docs/ASYNC_RUST_TRAINING.md) guide.
+> **Deep dive**: For production async patterns (stream processing, graceful shutdown, connection pooling, cancellation safety), see the companion [Async Rust Training](../../async-book/src/summary.md) guide.
 >
 > **Prerequisites**: [Ownership & Borrowing](ch07-ownership-and-borrowing.md) and [Smart Pointers](ch07-3-smart-pointers-beyond-single-ownership.md) (Rc vs Arc decision tree).
 

csharp-book/src/ch14-unsafe-rust-and-ffi.md

@@ -7,7 +7,7 @@
 
 Unsafe Rust allows you to perform operations that the borrow checker cannot verify. Use it sparingly and with clear documentation.
 
-> **Advanced coverage**: For safe abstraction patterns over unsafe code (arena allocators, lock-free structures, custom vtables), see [Rust Patterns](../../source-docs/RUST_PATTERNS.md).
+> **Advanced coverage**: For safe abstraction patterns over unsafe code (arena allocators, lock-free structures, custom vtables), see [Rust Patterns](../../rust-patterns-book/src/summary.md).
 
 ### When You Need Unsafe
 ```rust

csharp-book/src/ch16-3-rust-tooling-ecosystem.md

@@ -119,7 +119,7 @@ cargo expand module_name      # Expand specific module
 
 For deeper exploration of advanced topics mentioned in this guide, see the companion training documents:
 
-- **[Rust Patterns](../../source-docs/RUST_PATTERNS.md)** — Pin projections, custom allocators, arena patterns, lock-free data structures, and advanced unsafe patterns
-- **[Async Rust Training](../../source-docs/ASYNC_RUST_TRAINING.md)** — Deep dive into tokio, async cancellation safety, stream processing, and production async architectures
-- **[Rust Training for C++ Developers](./RUST_TRAINING_FOR_CPP.md)** — Useful if your team also has C++ experience; covers move semantics mapping, RAII differences, and template vs generics
-- **[Rust Training for C Developers](./RUST_TRAINING_FOR_C.md)** — Relevant for interop scenarios; covers FFI patterns, embedded Rust debugging, and `no_std` programming
+- **[Rust Patterns](../../rust-patterns-book/src/SUMMARY.md)** — Pin projections, custom allocators, arena patterns, lock-free data structures, and advanced unsafe patterns
+- **[Async Rust Training](../../async-book/src/SUMMARY.md)** — Deep dive into tokio, async cancellation safety, stream processing, and production async architectures
+- **[Rust Training for C++ Developers](../../c-cpp-book/src/SUMMARY.md)** — Useful if your team also has C++ experience; covers move semantics mapping, RAII differences, and template vs generics
+- **[Rust Training for C Developers](../../c-cpp-book/src/SUMMARY.md)** — Relevant for interop scenarios; covers FFI patterns, embedded Rust debugging, and `no_std` programming

type-driven-correctness-book/src/ch00-introduction.md

@@ -8,7 +8,7 @@
 
 ---
 
-A practical guide to using Rust's type system to make entire classes of bugs **impossible to compile**. While the companion [Rust Patterns](../rust-patterns-book/index.html) book covers the mechanics (traits, associated types, type-state), this guide shows how to **apply** those mechanics to real-world domains — hardware diagnostics, cryptography, protocol validation, and embedded systems.
+A practical guide to using Rust's type system to make entire classes of bugs **impossible to compile**. While the companion [Rust Patterns](../../rust-patterns-book/src/SUMMARY.md) book covers the mechanics (traits, associated types, type-state), this guide shows how to **apply** those mechanics to real-world domains — hardware diagnostics, cryptography, protocol validation, and embedded systems.
 
 Every pattern here follows one principle: **push invariants from runtime checks into the type system so the compiler enforces them.**
 
@@ -61,11 +61,11 @@ Every pattern here follows one principle: **push invariants from runtime checks
 
 | Concept | Where to learn it |
 |---------|-------------------|
-| Ownership and borrowing | [Rust Patterns](../rust-patterns-book/index.html), ch01 |
-| Traits and associated types | [Rust Patterns](../rust-patterns-book/index.html), ch02 |
-| Newtypes and type-state | [Rust Patterns](../rust-patterns-book/index.html), ch03 |
-| PhantomData | [Rust Patterns](../rust-patterns-book/index.html), ch04 |
-| Generics and trait bounds | [Rust Patterns](../rust-patterns-book/index.html), ch01 |
+| Ownership and borrowing | [Rust Patterns](../rust-patterns-book/src/SUMMARY.md), ch01 |
+| Traits and associated types | [Rust Patterns](../rust-patterns-book/src/SUMMARY.md), ch02 |
+| Newtypes and type-state | [Rust Patterns](../rust-patterns-book/src/SUMMARY.md), ch03 |
+| PhantomData | [Rust Patterns](../rust-patterns-book/src/SUMMARY.md), ch04 |
+| Generics and trait bounds | [Rust Patterns](../rust-patterns-book/src/SUMMARY.md), ch01 |
 
 ## The Correct-by-Construction Spectrum
 

xtask/src/main.rs

@@ -289,10 +289,68 @@ fn write_landing_page(site: &Path) {
     println!("  ✓ index.html");
 }
 
+/// Resolve `request_target` (HTTP request path, e.g. `/foo/bar?x=1`) to a file under `site_canon`.
+/// Returns `None` for traversal attempts, missing files, or paths that escape `site_canon` (symlinks).
+fn resolve_site_file(site_canon: &Path, request_target: &str) -> Option<PathBuf> {
+    let path_only = request_target.split('?').next()?.split('#').next()?;
+    let decoded = percent_decode_path(path_only);
+    if decoded.as_bytes().contains(&0) {
+        return None;
+    }
+    let rel = decoded.trim_start_matches('/');
+    let mut file_path = site_canon.to_path_buf();
+    if !rel.is_empty() {
+        for seg in rel.split('/').filter(|s| !s.is_empty()) {
+            if seg == ".." {
+                return None;
+            }
+            file_path.push(seg);
+        }
+    }
+    if file_path.is_dir() {
+        file_path.push("index.html");
+    }
+    let real = fs::canonicalize(&file_path).ok()?;
+    if !real.starts_with(site_canon) {
+        return None;
+    }
+    real.is_file().then_some(real)
+}
+
+fn hex_val(c: u8) -> Option<u8> {
+    match c {
+        b'0'..=b'9' => Some(c - b'0'),
+        b'a'..=b'f' => Some(c - b'a' + 10),
+        b'A'..=b'F' => Some(c - b'A' + 10),
+        _ => None,
+    }
+}
+
+fn percent_decode_path(input: &str) -> String {
+    let mut decoded = Vec::with_capacity(input.len());
+    let b = input.as_bytes();
+    let mut i = 0;
+    while i < b.len() {
+        if b[i] == b'%' && i + 2 < b.len() {
+            if let (Some(hi), Some(lo)) = (hex_val(b[i + 1]), hex_val(b[i + 2])) {
+                decoded.push(hi << 4 | lo);
+                i += 3;
+                continue;
+            }
+        }
+        decoded.push(b[i]);
+        i += 1;
+    }
+    String::from_utf8_lossy(&decoded).into_owned()
+}
+
 // ── serve ────────────────────────────────────────────────────────────
 
 fn cmd_serve() {
     let site = project_root().join("site");
+    let site_canon = fs::canonicalize(&site).expect(
+        "site/ not found — run `cargo xtask build` first (e.g. `cargo xtask serve` runs build automatically)",
+    );
     let addr = "127.0.0.1:3000";
     let listener = TcpListener::bind(addr).expect("failed to bind port 3000");
 
@@ -313,12 +371,7 @@ fn cmd_serve() {
             .and_then(|line| line.split_whitespace().nth(1))
             .unwrap_or("/");
 
-        let mut file_path = site.join(path.trim_start_matches('/'));
-        if file_path.is_dir() {
-            file_path = file_path.join("index.html");
-        }
-
-        if file_path.is_file() {
+        if let Some(file_path) = resolve_site_file(&site_canon, path) {
             let body = fs::read(&file_path).unwrap_or_default();
             let mime = guess_mime(&file_path);
             let header = format!(
@@ -404,4 +457,4 @@ fn cmd_clean() {
             println!("Removed {dir_name}/");
         }
     }
-}
+}