Merge branch 'perf/lag': dashboard lag fixes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

# Conflicts:
#	client/src/components/Sagi/PetSprite.tsx
#	client/src/components/Sagi/useSagiBrain.ts

docs/API.md

@@ -2118,6 +2118,7 @@ Response `Content-Type: text/plain; version=0.0.4; charset=utf-8`.
 | `agenthub_build_info` | gauge | `version` | Always `1`; dashboard version rides on the label |
 | `agenthub_process_uptime_seconds` | gauge | — | Server process uptime |
 | `agenthub_process_resident_memory_bytes` | gauge | — | Server process RSS |
+| `agenthub_event_loop_delay_seconds` | gauge | `quantile` (`0.5`, `0.99`, `1` = max) | Event-loop delay over the last minute — how long requests, hooks and terminal echo waited (a laggy terminal shows here) |
 | `agenthub_sessions` | gauge | `status` (`active`/`completed`/`error`/`abandoned`) | Sessions by status |
 | `agenthub_agents` | gauge | `status` (`working`/`waiting`/`completed`/`error`) | Agents by status |
 | `agenthub_events_total` | counter | — | Total events recorded |

docs/HOOKS.md

@@ -182,7 +182,7 @@ npm run install-hooks
 > (Escape hatch for running Claude Code *inside* the same container:
 > `AGENTHUB_ALLOW_CONTAINER_HOOKS=1 npm run install-hooks`.)
 
-For each of the eight hook types it adds one entry to `~/.claude/settings.json` that runs the handler with the type as its argument; the five tool/turn hooks (`PreToolUse`, `PostToolUse`, `Stop`, `SubagentStop`, `Notification`) carry `"matcher": "*"`. Entries that are not AgentHub's are left alone. There is nothing else to install — Claude Code runs `scripts/hook-handler.js` directly.
+For each of the eight hook types it adds one entry to `~/.claude/settings.json` that runs the handler with the type as its argument; the five tool/turn hooks (`PreToolUse`, `PostToolUse`, `Stop`, `SubagentStop`, `Notification`) carry `"matcher": "*"`. `PreToolUse` and `PostToolUse` also carry `"async": true` (`ASYNC_HOOKS` in `scripts/install-hooks.js`, and the same in `.claude-plugin/plugin.json`): they fire around every tool call, and Claude Code waits for a synchronous hook before going on — each a Node start of 0.1–0.2 s, so ~0.4 s added to every tool call. The handler only reports (it prints nothing and decides nothing), so nothing is lost by not waiting; the rarer hooks stay synchronous so a turn's start and end reach the dashboard in order. Entries that are not AgentHub's are left alone. There is nothing else to install — Claude Code runs `scripts/hook-handler.js` directly.
 
 ```json
 {
@@ -191,7 +191,7 @@ For each of the eight hook types it adds one entry to `~/.claude/settings.json`
       {
         "matcher": "*",
         "hooks": [
-          { "type": "command", "command": "node \"/path/to/agenthub/scripts/hook-handler.js\" PreToolUse" }
+          { "type": "command", "command": "node \"/path/to/agenthub/scripts/hook-handler.js\" PreToolUse", "async": true }
         ]
       }
     ],

docs/MONITORING.md

@@ -24,7 +24,8 @@ as they are into an existing Grafana (Dashboards → New → Import).
 ## Metrics used
 
 `agenthub_up`, `agenthub_build_info{version}`, `agenthub_process_uptime_seconds`,
-`agenthub_process_resident_memory_bytes`, `agenthub_sessions{status}`,
+`agenthub_process_resident_memory_bytes`, `agenthub_event_loop_delay_seconds{quantile}`,
+`agenthub_sessions{status}`,
 `agenthub_agents{status}`, `agenthub_events_total`, `agenthub_websocket_clients`,
 `agenthub_remote_sources{enabled}`, `agenthub_tokens_total{kind}`.
 

docs/SERVER-MODE.md

@@ -797,7 +797,9 @@ What a new machine still needs by hand after it:
    `PostToolUse` (both with `"matcher": "*"`), `Stop`, `SubagentStop`,
    `Notification`, `SessionStart`, `SessionEnd` and `UserPromptSubmit`, a
    `command` hook `/opt/agenthub/libexec/member-hook <Event>` with
-   `"timeout": 5`.
+   `"timeout": 5` — and `"async": true` on `PreToolUse` and `PostToolUse`, so
+   Claude Code does not wait a Node start before and after every tool call.
+   Re-running `install-system` rewrites a managed file it wrote itself.
 5. Any other daemon that must see every process (monitoring agents, for
    example) needs group `agenthub-proc`: `sudo usermod -aG agenthub-proc <it>`.
 6. A tool `agenthub server tools` reports as `ESHAREDLAYOUT` (a script in a