Fleet UI Phase 5: Event feed, overlaps, merge pipeline

[Wirasm]

Phase 5: Event Feed & Advanced Intelligence

Part of #562 (Fleet UI Epic)

PRD: .claude/PRPs/prds/fleet-ui-honryu-visibility.prd.md — Phase 5

What

Real-time event feed, file overlap detection, and merge pipeline visibility in the Fleet view.

Why

Completes full CLI parity. The event feed shows what's happening in real-time. Overlaps warn about file conflicts before they become merge problems. The merge pipeline shows which workers are ready to land.

Scope

5.1 Event Feed

• Ring buffer (VecDeque<FleetEvent>, max 100) in FleetStore
• Derived from: history.jsonl diffs + agent status transitions
• Collapsible panel below fleet table
• Each event: timestamp + colored dot + branch + summary
• Auto-scrolls to bottom on new events
• 5s refresh interval

5.2 Overlap Detection

• overlaps: Option<OverlapReport> in FleetStore
• Calls kild_core::git::collect_file_overlaps(sessions, base_branch)
• 60s refresh or on-demand (expensive — opens git repos)
• Warning banner above fleet table when conflicts exist
• Ember-colored, clickable to expand full overlap details

5.3 Merge Pipeline

• merge_readiness: HashMap<String, MergeReadiness> in FleetStore
• pr_info: HashMap<String, PrInfo> in FleetStore
• 60s refresh or on-demand (expensive — git + network)
• Fleet table gets columns: PR #, CI status, Merge readiness
• Color-coded: Ready=aurora, NeedsPush/NeedsRebase=copper, HasConflicts/CiFailing=ember
• Detail view: "Merge" section with PR link, CI, review, readiness

Files

• crates/kild-ui/src/state/fleet.rs — events, overlaps, merge readiness, PR info
• crates/kild-ui/src/views/dashboard_view.rs — event feed, overlap banner, merge columns
• crates/kild-ui/src/views/detail_view.rs — merge section

Depends on

• Fleet UI Phase 1: Agent status visibility #563 (Phase 1: FleetStore)
• Fleet UI Phase 2: Dropbox / task visibility #564 (Phase 2: Dropbox)
• Fleet UI Phase 3: Fleet command center + inject #566 (Phase 3: Fleet table)