feat: add developer-mode startup and stack hydration timing (#1619)

* feat: add developer-mode startup and stack hydration timing

Instrument boot-to-list and detail hydration with commit-aligned milestones, truthful request stages, and destination/gateway debug duration logs so performance work is guided by measurements.

* fix: redact stack names and complete hydration request stages

Stop logging stack identifiers in containers debug timing, and record state_dispatch (plus detail fetch spans) so copied reports match the advertised stage breakdown.

frontend/src/context/AuthContext.tsx

@@ -1,4 +1,5 @@
 import { createContext, useContext, useState, useEffect, useCallback, type ReactNode } from 'react';
+import { markMilestone } from '@/lib/hydrationTiming';
 
 type AppStatus = 'loading' | 'needsSetup' | 'notAuthenticated' | 'mfaChallenge' | 'authenticated';
 
@@ -109,6 +110,13 @@ export function AuthProvider({ children }: { children: ReactNode }) {
     }
   };
 
+  // One-shot boot milestone: the auth gate has resolved to a terminal status
+  // (setup, login, MFA, or authenticated), so the app can leave the splash.
+  useEffect(() => {
+    if (appStatus === 'loading') return;
+    markMilestone('auth_resolved');
+  }, [appStatus]);
+
   useEffect(() => {
     checkAuth();
     const handleUnauthorized = () => {

frontend/src/context/NodeContext.tsx

@@ -1,5 +1,6 @@
 import React, { createContext, useContext, useState, useEffect, useCallback, useRef, useMemo } from 'react';
 import { apiFetch } from '@/lib/api';
+import { beginNodeSession, markMilestone } from '@/lib/hydrationTiming';
 import type { Capability } from '@/lib/capabilities';
 
 export type NodeMode = 'proxy' | 'pilot_agent';
@@ -56,6 +57,18 @@ export function NodeProvider({ children }: { children: React.ReactNode }) {
   const nodeMetaRef = useRef<Map<number, NodeMeta>>(nodeMeta);
   nodeMetaRef.current = nodeMeta;
 
+  // Open a fresh hydration-timing session the moment the active node id changes,
+  // during render (guarded by a ref to fire once per id). This must precede the
+  // shell's stack-list refresh so its attempt binds to the new node session:
+  // child effects (EditorLayout's node-switch effect that calls refreshStacks)
+  // run before this provider's effects, so an effect here would begin the
+  // session too late and the list milestone would never commit.
+  const hydrationNodeRef = useRef<number | null>(null);
+  if (activeNode && hydrationNodeRef.current !== activeNode.id) {
+    hydrationNodeRef.current = activeNode.id;
+    beginNodeSession(activeNode.id);
+  }
+
   const fetchNodeMeta = useCallback(async (nodeId: number, force = false) => {
     const cached = nodeMetaRef.current.get(nodeId);
     if (cached && !force) {
@@ -157,6 +170,13 @@ export function NodeProvider({ children }: { children: React.ReactNode }) {
     return () => window.removeEventListener('node-not-found', handleNodeNotFound);
   }, [refreshNodes]);
 
+  // One-shot boot milestone: nodes have finished loading and an active node is
+  // resolved. Deduped by the store, so a later re-run is a no-op.
+  useEffect(() => {
+    if (isLoading || !activeNode) return;
+    markMilestone('nodes_resolved');
+  }, [isLoading, activeNode]);
+
   const activeNodeMeta = useMemo(() => {
     if (!activeNode) return null;
     return nodeMeta.get(activeNode.id) ?? null;