docs: add design spec for host overview info section

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/superpowers/specs/2026-05-10-host-overview-info-section-design.md

@@ -0,0 +1,135 @@
+# Host Overview Info Section
+
+**Date:** 2026-05-10  
+**Status:** Approved
+
+## Summary
+
+Add an always-visible info section to each host card on the Host Overview (`/plugins`) page. The section shows owner, managers, agent version/type, last packet timestamp, and the host's effective alert thresholds. The fields `hbc_version` and `hbc_type` are moved out of the `os_info` plugin accordion into this section.
+
+---
+
+## Backend: New API Endpoint
+
+**Route:** `GET /api/0/hosts/{hostname}/info`
+
+**Auth:** Same as other per-host endpoints (`_can_view_host`).
+
+**Response schema:**
+
+```json
+{
+  "owner":       "alice",
+  "managers":    ["bob", "carol"],
+  "hbc_version": "5.3.0",
+  "hbc_type":    "full",
+  "last_packet": 1746894000.0,
+  "thresholds": [
+    {
+      "metric":    "cpu_monitor.cpu_percent",
+      "warning":   80.0,
+      "critical":  95.0,
+      "operator":  ">"
+    }
+  ]
+}
+```
+
+**Field details:**
+
+- `owner` — `host.owner`, or `null` if unset.
+- `managers` — `host.managers` list (may be empty).
+- `hbc_version` — from `host.get_latest_plugin_data("os_info")`, key `hbc_version`; `null` if no os_info data.
+- `hbc_type` — same source, key `hbc_type`; `null` if unavailable.
+- `last_packet` — `max(conn.lastbeat for conn in host.connections.values())`, or `null` if no connections.
+- `thresholds` — list derived from `threshold_checker.get_thresholds_for_host(hostname)`, sorted by `metric` ascending. Each entry includes `metric`, `warning` (null if unset), `critical` (null if unset), `operator`. Returns `null` (not `[]`) if no `threshold_checker` is configured, so the frontend can distinguish "not configured" from "configured but empty".
+
+**Location:** `hbd/server/http.py`, added alongside the other `api_host_*` functions. Registered as `web.get("/api/0/hosts/{hostname}/info", api_host_info)`.
+
+---
+
+## Frontend: Info Section
+
+### HTML structure
+
+Inserted as the first child of `.host-body`, before the plugin accordions. It is not a collapsible accordion — it is always visible when the host card is expanded.
+
+```html
+<div class="host-info-section" id="info-{hostname}">
+  <div class="loading">Loading…</div>
+</div>
+```
+
+### Fetch lifecycle
+
+- Fetched once per host on the first expansion of the host card (same trigger as the glance/plugin data).
+- Result cached in a new per-host `infoCache` object (parallel to `pluginCache`).
+- On subsequent expansions the cached data is rendered immediately without a new request.
+
+### Rendered layout
+
+Two logical areas rendered client-side from the JSON:
+
+**Meta row** — a CSS-grid or simple `<dl>` showing:
+
+| Label         | Value                        |
+|---------------|------------------------------|
+| Owner         | alice (or "—" if null)       |
+| Managers      | bob, carol (or "—" if empty) |
+| Agent Version | 5.3.0 (or "—")               |
+| Agent Type    | full (or "—")                |
+| Last Packet   | localized datetime string (or "—") |
+
+**Threshold table** — rendered with the existing `data-table` CSS class:
+
+| Metric | Operator | Warning | Critical |
+|--------|----------|---------|----------|
+| cpu_monitor.cpu_percent | > | 80 | 95 |
+| … | … | … | … |
+
+- If `thresholds` is `null`: show "Threshold alerting not configured."
+- If `thresholds` is `[]`: show "No thresholds defined."
+- Numeric threshold values rendered as-is (no units); `null` warning/critical shown as "—".
+
+### CSS
+
+New `.host-info-section` styles added in the `<style>` block of `plugins.html`. The section gets a subtle background (e.g. `#fafafa`) and a bottom border to separate it visually from the plugin accordions below. The meta row uses a two-column grid layout for compactness.
+
+---
+
+## Changes to `renderOsInfoTable()`
+
+- Remove `hbc_version` from the `ORDER` array.
+- Add `hbc_type` to the `SKIP_FIELDS` set (or the local `shown` set) so it is excluded from the os_info table.
+
+Both fields will now appear only in the info section.
+
+---
+
+## Data Flow Summary
+
+```
+User expands host card
+  → toggleHost()
+    → fetchGlanceData(hostname)   [existing, unchanged]
+    → fetchInfoData(hostname)     [new]
+        GET /api/0/hosts/{hostname}/info
+        → renderInfoSection(hostname, data)
+          → writes into #info-{hostname}
+```
+
+---
+
+## Error Handling
+
+- If the info fetch fails (non-200), show a one-line error message in the info section ("Could not load host info.").
+- If `hbc_version`/`hbc_type` are null (host has never sent os_info), display "—".
+- If `last_packet` is null (no connections recorded), display "—".
+
+---
+
+## Out of Scope
+
+- Editing owner/managers from this section (covered by existing profile/access UI).
+- Editing thresholds from this section.
+- Monitors list (not shown — monitors are operational, not informational in this context).