Add BrokerPort: loopd asks brokerd for every tool call

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/loopd/src/baseline.rs

@@ -25,6 +25,7 @@ pub enum BaselineError {
     Read(PathBuf, std::io::Error),
     Parse(PathBuf, serde_json::Error),
     Hash,
+    Core(PathBuf, std::io::Error),
 }
 
 impl std::fmt::Display for BaselineError {
@@ -33,6 +34,11 @@ impl std::fmt::Display for BaselineError {
             BaselineError::Read(path, err) => write!(f, "{}: {err}", path.display()),
             BaselineError::Parse(path, err) => write!(f, "{}: {err}", path.display()),
             BaselineError::Hash => write!(f, "hashing the baseline failed"),
+            BaselineError::Core(path, err) => write!(
+                f,
+                "{}: {err}; see docs/runbook.md#core-memory-unreadable",
+                path.display()
+            ),
         }
     }
 }
@@ -58,7 +64,7 @@ impl Baseline {
             // A missing file is fine; an unreadable one is reported so the owner is not given a
             // session without the memory they curated and no sign of it.
             Err(e) if e.kind() != std::io::ErrorKind::NotFound => {
-                return Err(BaselineError::Read(core.clone(), e));
+                return Err(BaselineError::Core(core.clone(), e));
             }
             Err(_) => {}
         }