---
phase: 14-preview-bridge-infrastructure
plan: 02
subsystem: ui
tags: [preview, html, javascript, css, devtools, resource-picker, bridge-logging, iframe]

# Dependency graph
requires:
  - phase: 14-preview-bridge-infrastructure
    provides: "API endpoints for /api/resources, /api/resources/read, /api/reconnect, /api/status"
provides:
  - "Auto-load first UI resource widget on preview startup"
  - "Resource picker with single-label and multi-list modes"
  - "Bridge call logging with expandable details/summary in Network tab"
  - "Network tab badge count for unread bridge calls"
  - "Per-tab clear buttons for Console, Network, Events"
  - "Connection status dot with connected/disconnected/reconnecting states"
  - "Reconnect button for session reset and reload"
  - "Inline widget error display with retry capability"
affects: [15-wasm-bridge, 16-bridge-contract, 17-apps-sdk]

# Tech tracking
tech-stack:
  added: []
  patterns: [resource-auto-load, expandable-details-summary, badge-count-tracking, per-tab-clear]

key-files:
  created: []
  modified:
    - crates/mcp-preview/assets/index.html

key-decisions:
  - "Used details/summary HTML elements for expandable bridge call entries in Network tab (native browser support, no library needed)"
  - "Badge count auto-clears when Network tab is selected (avoids stale badge after viewing)"
  - "Resource picker renders as label for single resource, clickable list for multiple (avoids unnecessary dropdown for common case)"

patterns-established:
  - "Resource auto-load: initSession() fetches tools and resources in parallel, auto-loads first HTML resource"
  - "Bridge call logging: callTool() captures start/end time and logs via logBridgeCall() to parent runtime"
  - "Badge count pattern: increment on log, reset on tab selection and clear"

requirements-completed: [PREV-01, PREV-05, PREV-06, PREV-07]

# Metrics
duration: 3min
completed: 2026-02-24
---

# Phase 14 Plan 02: Preview UI Enhancement Summary

**Resource picker with auto-load, expandable bridge call logging with badge counts, connection status with reconnect, and per-tab clear buttons in preview DevTools**

## Performance

- **Duration:** 3 min
- **Started:** 2026-02-24T22:09:45Z
- **Completed:** 2026-02-24T22:13:16Z
- **Tasks:** 2
- **Files modified:** 1

## Accomplishments
- Preview UI auto-loads the first UI resource widget on startup via initSession() which fetches /api/tools and /api/resources in parallel
- Resource picker renders above the tool list with label mode (1 resource) or clickable list mode (multiple resources)
- Bridge callTool() wired to logBridgeCall() with timing, producing expandable details/summary entries in Network tab showing tool name, args, response, and duration
- Network tab badge count tracks unread bridge calls, clears on tab selection or clear button
- Per-tab clear buttons added to Console, Network, and Events tabs (State tab excluded per spec)
- Connection status dot reflects actual MCP session state with connected (green), disconnected (red), and reconnecting (orange) states
- Reconnect button in header resets session via POST /api/reconnect and reloads tools and resources
- Error states displayed inline in widget area with retry button

## Task Commits

Each task was committed atomically:

1. **Task 1: Add resource picker, auto-load, connection status, and reconnect** - `cc77347` (feat)
2. **Task 2: Enhance DevTools with bridge call logging, badge counts, and clear buttons** - `dac1893` (feat)

## Files Created/Modified
- `crates/mcp-preview/assets/index.html` - Complete preview UI with resource management, enhanced DevTools, connection lifecycle, and error handling

## Decisions Made
- Used native HTML `<details>/<summary>` elements for expandable Network tab entries instead of custom JS toggle (simpler, accessible, no library)
- Badge count auto-clears when user clicks the Network tab to avoid stale unread indicators
- Resource picker shows just a label when single resource exists (avoids unnecessary interaction for the common single-widget case)
- Error state uses dynamically created DOM element with retry button rather than a permanent hidden element (cleaner DOM when no errors)

## Deviations from Plan

None - plan executed exactly as written.

## Issues Encountered
None

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- Full preview UI complete: resource auto-load, resource switching, bridge call logging, connection lifecycle
- Phase 14 (Preview Bridge Infrastructure) is now fully complete -- both backend API (14-01) and frontend UI (14-02)
- Phase 15 (WASM Bridge) can build on the established bridge call patterns and DevTools logging infrastructure
- Phase 16 (Bridge Contract) can reference the bridge API surface implemented in wrapWidgetHtml()

## Self-Check: PASSED

All files verified present. All commit hashes verified in git log.

---
*Phase: 14-preview-bridge-infrastructure*
*Completed: 2026-02-24*
