hive-ag3nt: scrub mcp.rs cookies (#716 batch 8)

Last #716 hotspot — scrub-only batch. All substantive prose is
already documented in docs/turn-loop.md::MCP surface (Sub-agent
tools, Manager tools, Tool whitelist, Tool envelope), so the 10
cookies in mcp.rs come out without prose extraction.

- format_agent_meta rustdoc: drop #432 attribution, add docs pointer
  for the running=false / status_text-stale rationale
- get_agent_meta hive/swarm comment: drop #710 attribution
- AgentServer + ManagerServer add-tool warnings: drop #511 attribution
  twice (kept the lockstep invariant)
- edit_schedule description: drop #474 + #478 cookies in user-facing
  tool text
- cancel_loose_end description: drop #250 cookie in user-facing text
- Manager allow-list block: drop the long #444/#235/#467/#472/#474/
  #478/#509 attribution roll, keep the lockstep invariant
- check_send_allowed (<parent> branch): drop #692, replace with the
  actual semantics ("falls back to operator for root agents")
- prompts/system.md: drop #474 cookie from edit_schedule line
- Cargo.toml [[bin]]: drop #598 pre-/post- split history, add docs
  pointer to docs/turn-loop.md::Harness binary shape

cargo check + 56 tests pass.
Closes #716 (last cookie hotspot).

hive-ag3nt/src/mcp.rs

@@ -295,9 +295,10 @@ fn loose_end_kind_label(kind: hive_sh4re::CancelLooseEndKind) -> &'static str {
 /// `hyperhive_rev`, and `running` are always shown; `status` only
 /// appears when one is set, otherwise the line reads `status: <none>`.
 /// When `running` is false the host has already cleared `status_text`
-/// (it would be stale from before the stop, #432) so the status line
-/// is implicitly `<none>` in that case — but the explicit `running:
-/// no` line tells the caller WHY.
+/// (it would be a stale snapshot from before the stop) so the status
+/// line is implicitly `<none>` in that case — but the explicit
+/// `running: no` line tells the caller WHY. See
+/// `docs/turn-loop.md::Sub-agent tools` (`get_agent_meta`).
 #[must_use]
 pub fn format_agent_meta(resp: Result<SocketReply, anyhow::Error>) -> String {
     match resp {
@@ -315,8 +316,8 @@ pub fn format_agent_meta(resp: Result<SocketReply, anyhow::Error>) -> String {
             let run = if running { "yes" } else { "no" };
             let mut out =
                 format!("name: {name}\nrole: {role}\nhyperhive_rev: {rev}\nrunning: {run}");
-            // #710: surface hive + swarm display names only when set,
-            // so single-hive deployments don't see noisy `<none>` lines.
+            // Surface hive + swarm display names only when set, so
+            // single-hive deployments don't see noisy `<none>` lines.
             if let Some(hn) = hive_name.as_deref() {
                 use std::fmt::Write as _;
                 let _ = write!(out, "\nhive_name: {hn}");
@@ -507,8 +508,7 @@ impl AgentServer {
 // its name to `allowed_mcp_tools(Flavor::Agent)` below. Claude
 // Code's permission gate refuses uninlisted MCP tools in
 // non-interactive `--print` mode with "permissions not granted yet"
-// — same failure mode #511 cleaned up on the manager side. Keep the
-// two lists in lockstep.
+// — keep the two lists in lockstep.
 #[tool_router]
 impl AgentServer {
     #[tool(
@@ -1102,8 +1102,7 @@ impl ManagerServer {
 // its name to `allowed_mcp_tools(Flavor::Manager)` below. Claude
 // Code's permission gate refuses uninlisted MCP tools in
 // non-interactive `--print` mode with "permissions not granted yet"
-// — exactly the failure mode PR #511 cleaned up. Keep the two lists
-// in lockstep.
+// — keep the two lists in lockstep.
 #[tool_router]
 impl ManagerServer {
     #[tool(
@@ -1387,11 +1386,11 @@ impl ManagerServer {
     }
 
     #[tool(
-        description = "Edit an existing scheduled prompt's mutable fields (#474). Pass only \
+        description = "Edit an existing scheduled prompt's mutable fields. Pass only \
         the fields you want to change — anything omitted keeps its current value. Editable: \
         `body`, `description`, `interval_seconds` (positive only via this tool; flipping \
         recurring→one-shot is operator-only via the dashboard), `next_fire_at_unix`, and \
-        the target set via `targets_add` / `targets_remove` (#478). Both target lists are \
+        the target set via `targets_add` / `targets_remove`. Both target lists are \
         applied in the same transaction with removes-before-adds, so a single edit can \
         swap a target atomically. Re-adding a previously-removed target starts a fresh \
         per-target history (drops the tombstone). Draining all targets auto-cancels the \
@@ -1659,7 +1658,7 @@ impl ManagerServer {
         with the operator-override sentinel so the asker unblocks), a `reminder` \
         (hard-deleted before fire), or an `approval` (withdraws a pending approval \
         you submitted; the dashboard pulls the card from pending and the row resolves \
-        as `cancelled` instead of approved/denied/failed — closes #250). `kind` is \
+        as `cancelled` instead of approved/denied/failed). `kind` is \
         `\"question\"`, `\"reminder\"`, or `\"approval\"`; `id` is the row id from \
         `get_loose_ends` or the original submission reply. Manager surface bypasses \
         the owner check on the sub-agent flavour — use for hive-wide cleanup of \
@@ -1795,13 +1794,12 @@ pub fn allowed_mcp_tools(flavor: Flavor) -> Vec<String> {
             "restart",
             "update",
             "request_apply_commit",
-            // Tools added post-#444 / #235 / #467 / #472 / #474 / #478 that
-            // got missed in the allow-list when their `#[tool]` impls
-            // landed. Claude Code's permission gate refuses uninlisted
-            // tools in non-interactive `--print` mode with a "permissions
-            // not granted yet" error (hm1nd hit this trying to run the
-            // dedup pass for #509). Keep this block in lockstep with the
-            // `#[tool]` fns in the `ManagerServer` impl.
+            // The remaining manager tools below were added incrementally
+            // and have historically been missed in the allow-list when
+            // their `#[tool]` impls landed. Claude Code's permission gate
+            // refuses uninlisted tools in non-interactive `--print` mode
+            // with a "permissions not granted yet" error — keep this
+            // block in lockstep with the `#[tool]` fns in `ManagerServer`.
             "request_update_meta_inputs",
             "request_schedule_prompt",
             "fire_schedule_now",
@@ -1912,7 +1910,8 @@ fn check_send_allowed(to: &str) -> Result<(), String> {
         // can rewire who the parent IS via `set_parent` without
         // having to remember to update the per-agent allow-list.
         // The broker resolves the sentinel to the real parent label
-        // on the host side per topology.json (#692).
+        // on the host side per topology.json (falls back to `operator`
+        // for root agents).
         return Ok(());
     }
     let Ok(raw) = std::fs::read_to_string(SEND_ALLOW_PATH) else {