feat(room): gate every post on the floor (room, sidecar, screen, protocol 4)

.github/workflows/ci.yml

@@ -30,6 +30,7 @@ jobs:
             ~/.cargo/git
             src-tauri/target
             crates/mcp-config/target
+            crates/room-floor/target
           key: rust-${{ runner.os }}-${{ hashFiles('src-tauri/Cargo.lock') }}
           restore-keys: rust-${{ runner.os }}-
 
@@ -61,6 +62,10 @@ jobs:
         working-directory: crates/mcp-config
         run: cargo test
 
+      - name: Test the room-floor crate
+        working-directory: crates/room-floor
+        run: cargo test
+
   # Gate job: single Required status check for branch protection.
   # Add new jobs to `needs` when CI grows. No Settings change needed.
   CI:

crates/room-floor/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "room-floor"
+version = "0.1.0"
+description = "The floor of the liplus-chat room: what has been said, and who had seen it before speaking"
+authors = ["Liplus Project Contributors"]
+license = "Apache-2.0"
+edition = "2021"
+
+# Deliberately free of tauri, for the reason docs/0-requirements.md gives: a
+# test binary that links the tauri dependency tree does not load on the GNU
+# target, so pure logic left in `src-tauri/src/` is unverifiable the moment it
+# is written. The ordering this crate decides is the part of #47 that a reader
+# cannot check by reading, so it has to be the part a test can run.
+
+[dependencies]
+serde = { version = "1", features = ["derive"] }