refactor(#2455): split hive-agent-mcp into its own bin crate

hive-sh4re/src/lib.rs

@@ -18,6 +18,34 @@ pub mod wire_time;
 /// constant instead of a scattered magic value.
 pub const RECV_BATCH_MAX: u32 = 5;
 
+/// Banner prepended to a wake prompt / `recv` result when the message was
+/// redelivered after a harness restart (the turn that first drove it never
+/// acked). Shared between the harness serve loop (wake prompt) and the MCP
+/// server (`recv` tool result) so both surfaces phrase it identically.
+pub const REDELIVERY_HINT: &str = "[redelivered after harness restart — may already be handled]\n";
+
+/// Shared "(N more message(s) pending …)" advisory appended after both the
+/// wake prompt body and the `recv` tool result whenever the inbox still has
+/// queued messages once the current message/batch is popped. Returns an empty
+/// string when `remaining == 0`. The leading `\n\n` separates it from the
+/// preceding body/message block, and the suggested `max` is clamped to the
+/// server-side recv cap so the hint never asks for more than one round-trip
+/// can deliver. One builder so the wake prompt (harness serve loop) and the
+/// in-turn recv result (MCP server) stay identical.
+#[must_use]
+pub fn pending_hint(remaining: u64) -> String {
+    if remaining == 0 {
+        return String::new();
+    }
+    let batch = remaining.min(u64::from(RECV_BATCH_MAX));
+    format!(
+        "\n\n({remaining} more message(s) pending in your inbox — call `mcp__hyperhive__recv` \
+         with `max: {batch}` to drain the next batch before acting. If the \
+         backlog is stale/already handled, `ack_until(up_to: <highest [msg #N] seen>)` \
+         clears everything up to that id in one call instead.)"
+    )
+}
+
 /// One row in the approval queue. `commit_ref` is overloaded per
 /// `kind` — see `docs/approvals.md::Approval kinds (wire shapes)`
 /// for the encoding table and lifecycle.