feat: add session modes and MCP capabilities support

Change-Id: I5db6760df4ae4f89ebacc3f1cc83f15d95afd0b9
Signed-off-by: Thomas Kosiewski <tk@coder.com>

Author: ThomasK33

.gitignore

@@ -20,3 +20,5 @@ typescript/docs/
 
 .envrc
 .direnv
+.rustup/
+.cargo/

flake.nix

@@ -24,17 +24,16 @@
 
         formatter = pkgs.nixfmt-rfc-style;
 
-        # Rust toolchain derived from rust-toolchain.toml
-        # Uses oxalica/rust-overlay to match the pinned channel/components.
-        rustToolchain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
+        # Use rustup to manage toolchains so `cargo +nightly` works in dev shell
+        rustup = pkgs.rustup;
       in
       {
         inherit formatter;
 
         devShells.default = pkgs.mkShell {
           packages = with pkgs; [
-            # Rust toolchain pinned via rust-toolchain.toml
-            rustToolchain
+            # Rustup manages stable/nightly toolchains according to rust-toolchain.toml
+            rustup
             pkg-config
             openssl
 
@@ -49,6 +48,30 @@
           ];
 
           RUST_BACKTRACE = "1";
+
+          # Ensure rustup shims are used and install required toolchains on first entry
+          shellHook = ''
+            export RUSTUP_HOME="$PWD/.rustup"
+            export CARGO_HOME="$PWD/.cargo"
+            export PATH="$CARGO_HOME/bin:$PATH"
+
+            if ! command -v rustup >/dev/null 2>&1; then
+              echo "rustup not found in PATH" 1>&2
+            else
+              # Install toolchains if missing; respect pinned channel from rust-toolchain.toml
+              if ! rustup toolchain list | grep -q nightly; then
+                rustup toolchain install nightly --profile minimal >/dev/null 2>&1 || true
+              fi
+              # Ensure stable toolchain from rust-toolchain.toml exists (rustup will auto-select it)
+              # Attempt to install channel specified in rust-toolchain.toml (fallback to stable)
+              TOOLCHAIN_CHANNEL=$(sed -n 's/^channel\s*=\s*"\(.*\)"/\1/p' rust-toolchain.toml || true)
+              if [ -n "$TOOLCHAIN_CHANNEL" ]; then
+                if ! rustup toolchain list | grep -q "$TOOLCHAIN_CHANNEL"; then
+                  rustup toolchain install "$TOOLCHAIN_CHANNEL" --profile minimal --component rustfmt clippy >/dev/null 2>&1 || true
+                fi
+              fi
+            fi
+          '';
         };
       }
     );