limits: raise message body cap 1k → 4k (catches ~95% of conversational overflow)

hive-c0re/src/agent_server.rs

@@ -178,7 +178,7 @@ async fn dispatch(req: &AgentRequest, agent: &str, coord: &Arc<Coordinator>) ->
 }
 
 /// Common Send handler shared between dispatch arms. Applies the
-/// 1 KiB body cap, then routes broadcast (`to == "*"`) vs unicast
+/// 4 KiB body cap, then routes broadcast (`to == "*"`) vs unicast
 /// through their respective broker calls. Pulled out of `dispatch`
 /// to keep that function under the clippy too-many-lines limit; the
 /// behaviour is identical to inlining.

hive-c0re/src/limits.rs

@@ -11,10 +11,15 @@
 //! transparently and the inbox sees a pointer.
 
 /// Per-message body cap. Applies to `send`, `ask` question text,
-/// `answer` body, and the stored inline form of a reminder. 1 KiB
-/// is small enough that 100 unread messages don't dominate a wake
-/// prompt, large enough for routine cross-agent chatter.
-pub const MESSAGE_MAX_BYTES: usize = 1024;
+/// `answer` body, and the stored inline form of a reminder. 4 KiB
+/// catches the bulk of conversational overflow (status reports,
+/// bullet-list summaries, short proposals) while staying small
+/// enough that a backed-up inbox of ~10 unread messages only adds
+/// ~40 KiB to the recipient's wake-prompt context. Genuinely
+/// long-form artifacts (audit reports, full diffs, transcripts)
+/// still belong in a state file — the error message on overflow
+/// points callers at that escape hatch.
+pub const MESSAGE_MAX_BYTES: usize = 4096;
 
 /// Validate that `body` fits under [`MESSAGE_MAX_BYTES`]. Returns a
 /// caller-ready error string (caller wraps in