Add Path Tracer onion timeline fork/merge with ghost branches and Seer feed.

Operators fork at hop N to run persona ensembles in parallel on the target agent until mining links; winners merge back into the canonical SQLite-persisted session with WS and Seer events plus mermaid branch graphs in the UI.

server/web/src/help/pathTracerTimeline.ts

@@ -0,0 +1,107 @@
+/**
+ * Onion timeline fork/merge helpers for Path Tracer UI + Seer/AI context.
+ */
+
+export type TimelineBranchStatus =
+  | 'canonical'
+  | 'running'
+  | 'won'
+  | 'lost'
+  | 'merged'
+  | 'failed'
+  | 'aborted';
+
+export interface PathTraceTimelineBranch {
+  id: string;
+  parent_id?: string;
+  fork_hop_index: number;
+  target_agent_id?: string;
+  target_agent_name?: string;
+  persona?: string;
+  spread_lanes?: string[];
+  status: TimelineBranchStatus;
+  mining_linked?: boolean;
+  hashrate?: number;
+  active_tier?: string;
+  error?: string;
+  is_ghost: boolean;
+  created_at?: string;
+  merged_at?: string;
+}
+
+export interface PathTraceTimelineWS {
+  session_id: string;
+  event: string;
+  branch?: PathTraceTimelineBranch;
+  branches?: PathTraceTimelineBranch[];
+  mermaid?: string;
+  target_agent_id?: string;
+}
+
+export function branchStatusLabel(status: TimelineBranchStatus): string {
+  switch (status) {
+    case 'canonical':
+      return 'canonical';
+    case 'running':
+      return 'exploring';
+    case 'won':
+      return 'mining linked';
+    case 'merged':
+      return 'merged';
+    case 'lost':
+      return 'lost';
+    case 'failed':
+      return 'failed';
+    case 'aborted':
+      return 'aborted';
+    default:
+      return status;
+  }
+}
+
+export function branchStatusClass(status: TimelineBranchStatus): string {
+  switch (status) {
+    case 'won':
+    case 'merged':
+      return 'won';
+    case 'running':
+      return 'running';
+    case 'failed':
+    case 'lost':
+    case 'aborted':
+      return 'failed';
+    case 'canonical':
+      return 'canonical';
+    default:
+      return 'ghost';
+  }
+}
+
+/** Ghost branches grouped under fork hop index for tree rendering. */
+export function ghostBranchesByHop(branches: PathTraceTimelineBranch[]): Map<number, PathTraceTimelineBranch[]> {
+  const map = new Map<number, PathTraceTimelineBranch[]>();
+  for (const b of branches) {
+    if (!b.is_ghost) continue;
+    const list = map.get(b.fork_hop_index) ?? [];
+    list.push(b);
+    map.set(b.fork_hop_index, list);
+  }
+  return map;
+}
+
+export function pickMergeCandidate(branches: PathTraceTimelineBranch[]): PathTraceTimelineBranch | null {
+  const ghosts = branches.filter((b) => b.is_ghost);
+  const won = ghosts.find((b) => b.status === 'won' || b.mining_linked);
+  if (won) return won;
+  const running = ghosts.find((b) => b.status === 'running');
+  return running ?? null;
+}
+
+export function mergeMermaidStyles(mermaid: string): string {
+  const styles = `classDef won fill:#0a3d2e,stroke:#00ffaa,color:#00ffaa
+classDef running fill:#3d320a,stroke:#ffc800,color:#ffc800
+classDef failed fill:#3d0a0a,stroke:#ff5050,color:#ff5050
+classDef ghost fill:#1a1a2e,stroke:#888,color:#ccc`;
+  if (mermaid.includes('classDef won')) return mermaid;
+  return `${mermaid.trim()}\n${styles}`;
+}