ci: declare MSRV and add MSRV check

.github/workflows/ci.yml

@@ -112,7 +112,33 @@
             --only-explicit-features \
             --features "$FEATURES"
 
+  msrv:
+    name: MSRV Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+
+      - name: Install Rust (MSRV)
+        uses: dtolnay/rust-toolchain@1.88
+
+      - uses: Swatinem/rust-cache@v2
+
+      # `rust-toolchain.toml` pins a newer dev toolchain and would otherwise
+      # override the toolchain installed above for in-repo `cargo` invocations.
+      # Forcing `RUSTUP_TOOLCHAIN` ensures the checks actually run on the MSRV.
+      - name: Check rmcp and rmcp-macros at MSRV
+        env:
+          RUSTUP_TOOLCHAIN: "1.88"
+        run: |
+          rustc --version
+          FEATURES=$(cargo metadata --no-deps --format-version 1 \
+            | jq -r '[.packages[] | select(.name == "rmcp") | .features | keys[]
+                      | select(startswith("__") | not)
+                      | select(. != "local")] | join(",")')
+          cargo check -p rmcp --features "$FEATURES"
+          cargo check -p rmcp-macros
+
   spelling:
     name: spell check with typos
     runs-on: ubuntu-latest
     steps:

Cargo.toml

@@ -9,6 +9,7 @@ rmcp-macros = { version = "1.8.0", path = "./crates/rmcp-macros" }
 
 [workspace.package]
 edition = "2024"
+rust-version = "1.88"
 version = "1.8.0"
 authors = ["4t145 <u4t145@163.com>"]
 license = "Apache-2.0"

crates/rmcp-macros/Cargo.toml

@@ -5,6 +5,7 @@ name = "rmcp-macros"
 license = { workspace = true }
 version = { workspace = true }
 edition = { workspace = true }
+rust-version = { workspace = true }
 repository = { workspace = true }
 homepage = { workspace = true }
 readme = { workspace = true }

crates/rmcp/Cargo.toml

@@ -3,6 +3,7 @@ name = "rmcp"
 license = { workspace = true }
 version = { workspace = true }
 edition = { workspace = true }
+rust-version = { workspace = true }
 repository = { workspace = true }
 homepage = { workspace = true }
 readme = { workspace = true }