docs: update architecture and changelog for subagent enhancement (#600)

docs/00-architecture-overview.md

@@ -112,8 +112,9 @@ flowchart TD
 | `internal/skills/` | SKILL.md loader (5-tier hierarchy) + BM25 search + hot-reload via fsnotify |
 | `internal/channels/` | Channel manager + adapters: Telegram (forum topics, STT, bot commands), Feishu/Lark (streaming cards, media), Zalo OA, Zalo Personal, Discord, WhatsApp, Slack |
 | `internal/mcp/` | MCP server bridge (stdio, SSE, streamable-HTTP transports) |
-| `internal/scheduler/` | Lane-based concurrency control (main, subagent, cron, team lanes) with per-session serialization |
+| `internal/scheduler/` | Lane-based concurrency control (main, subagent, cron, team lanes) with per-session serialization. Per-edition rate limits (`MaxSubagentConcurrent`, `MaxSubagentDepth`) with tenant-scoped concurrency |
 | `internal/memory/` | Memory system (pgvector hybrid search) |
+| `internal/subagent/` | Subagent lifecycle: spawn, roster, task persistence (subagent_tasks table), announce queue (producer-consumer), auto-retry, per-edition rate limiting |
 | `internal/permissions/` | RBAC policy engine (admin, operator, viewer roles) |
 | `internal/store/pg/pairing.go` | DM/device pairing service (8-character codes, database-backed) |
 | `internal/sandbox/` | Docker-based code execution sandbox |

docs/17-changelog.md

@@ -8,6 +8,20 @@ All notable changes to GoClaw Gateway are documented here. Format follows [Keep
 
 ### Added
 
+#### Parallel Sub-Agent Enhancement (#600) (2026-03-31)
+- **Smart leader delegation**: Conditional leader delegation prompt instead of forced delegation for all subagent spawns
+- **Compaction prompt persistence**: Preserves pending subagent and team task state across context summarization to maintain work continuity
+- **DB persistence**: `subagent_tasks` table (migration 000034) with `SubagentTaskStore` interface and PostgreSQL implementation. Write-through persistence from SubagentManager ensures durable task tracking
+- **Token cost tracking**: Per-subagent input/output token accumulation. Token costs included in announce messages and persisted in DB for billing/observability
+- **Per-edition rate limiting**: `MaxSubagentConcurrent` and `MaxSubagentDepth` limits on Edition struct. Tenant-scoped concurrency prevents single tenant from hogging subagent resources
+- **WaitAll orchestration**: `spawn(action=wait, timeout=N)` blocks parent until all spawned children complete. Enables coordinated multi-step workflows
+- **Auto-retry with backoff**: Configurable `MaxRetries` (default 2) with linear backoff for LLM failures. Improves reliability without manual intervention
+- **Producer-consumer announce queue**: Merges staggered subagent results into single LLM run announcement. Reduces token overhead vs per-result notifications
+- **Telegram subagent commands**: `/subagents` lists all active subagent tasks with status. `/subagent <id>` shows detailed view from DB
+- **Subagent blocking in subagents**: `SubagentDenyAlways` blocks `team_tasks` tool to prevent nested task delegation
+- **Functional options pattern**: Telegram provider refactored to `telegram.New()` with `WithXxxStore()` option setters for cleaner initialization
+- **File organization**: Subagent code split into focused modules: `subagent.go`, `subagent_roster.go`, `subagent_spawn.go`. Spawn tool split: `spawn_tool.go` + `spawn_tool_actions.go`
+
 #### Runtime & Packages Management (2026-03-17)
 - **Packages page**: New "Packages" page in Web UI under System group for managing installed packages
 - **HTTP API endpoints**: GET/POST `/v1/packages`, `/v1/packages/install`, `/v1/packages/uninstall`, GET `/v1/packages/runtimes`