Implements `delegate_to_agent` built-in tool (closes#63). Opt-in registration via `includeDelegateTool`; only wired up by `runTeam` / `runTasks` for pool workers. Guards: self-delegation, unknown target, cycle detection via `delegationChain`, depth cap (`maxDelegationDepth`, default 3), pool deadlock.
Delegation runs on ephemeral Agent instances via `AgentPool.runEphemeral` (pool semaphore only, no per-agent lock) so mutual delegation (A→B while B→A) can't deadlock. Delegated run `tokenUsage` surfaces via `ToolResult.metadata` and rolls into the parent runner's total before the next budget check; delegation tool_result blocks are exempt from `compressToolResults` and the `compact` strategy. Best-effort SharedMemory audit writes at `{caller}/delegation:{target}:{ts}-{rand}`.
Picks up @NamelessNATM's work from #84 and adds cycle detection, token aggregation, compression exemption, mutual-delegation deadlock fix (Codex P1), and tool_result-preservation on budget-exceeded (Codex P2).
Co-authored-by: NamelessNATM <hamzarstar@gmail.com>
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