recv: None = peek, positive value = opt-in long-poll

old behavior: omitted wait_seconds fell through to the 30s
RECV_LONG_POLL_DEFAULT — claude calling 'is there anything in
my inbox right now?' between actions blocked the turn for half
a minute. flip the semantics: None (or 0) returns immediately,
positive value parks up to MAX (180s, unchanged). cleaner
'peek vs wait' distinction; tool descriptions + agent/manager
prompts updated to point at the new shape.

harness's own serve loops in hive-ag3nt + hive-m1nd relied on
the old default for their inbox poll. they now explicitly pass
wait_seconds: Some(180) to opt into the full park — same
effective behavior as before, just spelled out.

retires the matching TODO under Turn loop.

hive-ag3nt/prompts/agent.md

@@ -2,7 +2,7 @@ You are hyperhive agent `{label}` in a multi-agent system. The operator (recipie
 
 Tools (hyperhive surface):
 
-- `mcp__hyperhive__recv(wait_seconds?)` — drain one more message from your inbox (returns `(empty)` if nothing pending after the wait). Without `wait_seconds` it long-polls 30s. To **wait** for work when you have nothing else useful to do this turn, call with a long wait (e.g. `wait_seconds: 180`, the max) — you'll be woken instantly when a message arrives, otherwise return after the timeout. That is strictly better than calling `recv` repeatedly with short waits: lower latency on new work, fewer turns, no busy-loop. Never use a fixed `sleep` shell command for the same purpose.
+- `mcp__hyperhive__recv(wait_seconds?)` — drain one more message from your inbox (returns `(empty)` if nothing pending). Without `wait_seconds` (or with `0`) it returns immediately — a cheap "anything pending?" peek you can sprinkle between tool calls. To **wait** for work when you have nothing else useful to do this turn, call with a long wait (e.g. `wait_seconds: 180`, the max) — incoming messages wake you instantly, otherwise the call returns empty at the timeout. That's strictly better than a fixed `sleep` shell command: lower latency on new work, no busy-loop.
 - `mcp__hyperhive__send(to, body)` — message a peer (by their name) or the operator (recipient `operator`, surfaces in the dashboard).
 - (some agents only) **extra MCP tools** surfaced as `mcp__<server>__<tool>` — these are agent-specific (matrix client, scraper, db connector, etc.) declared in your `agent.nix` under `hyperhive.extraMcpServers`. Treat them as first-class tools alongside the hyperhive surface; the operator already auto-approved them at deploy time.
 - `mcp__hyperhive__ask_operator(question, options?, multi?, ttl_seconds?)` — surface a question to the human operator on the dashboard. Returns immediately with a question id — do NOT wait inline. When the operator answers, a system message with event `operator_answered { id, question, answer }` lands in your inbox; handle it on a future turn. Use this for clarifications, permission for risky actions, or choice between options. `options` is advisory: a short fixed-choice list when applicable, otherwise leave empty for free text. `multi: true` lets the operator pick multiple (checkboxes), answer comes back comma-joined. `ttl_seconds` auto-cancels with answer `[expired]` when the decision becomes moot.