feat: add immutable scenes and upgrade the Node Flow site

analysis_options.yaml

@@ -7,6 +7,15 @@
 
 # The following line activates a set of recommended lints for Flutter apps,
 # packages, and plugins designed to encourage good coding practices.
+analyzer:
+  exclude:
+    - build/**
+    - android/**
+    - ios/**
+    - web/**
+    - windows/**
+    - macos/**
+    - linux/**
 include: package:flutter_lints/flutter.yaml
 
 linter:

packages/demo/analysis_options.yaml

@@ -7,6 +7,15 @@
 
 # The following line activates a set of recommended lints for Flutter apps,
 # packages, and plugins designed to encourage good coding practices.
+analyzer:
+  exclude:
+    - build/**
+    - android/**
+    - ios/**
+    - web/**
+    - windows/**
+    - macos/**
+    - linux/**
 include: package:flutter_lints/flutter.yaml
 
 linter:

packages/demo/integration_test/README.md

@@ -1,35 +1,41 @@
 # Rendered performance benchmark
 
 `node_flow_500_benchmark_test.dart` renders a deterministic graph with 500
-nodes and 955 connections. It warms the renderer and records separate pan,
+nodes by default (955 connections). It warms the renderer and records separate pan,
 zoom, single-node drag/drop, and node-plus-edge topology churn workloads using
 Flutter's engine-provided `FrameTiming` values. The topology workload
 alternately creates a visible node with two incident edges and removes that
-node with its edges, keeping the fixture near 500 nodes while exercising widget
+node with its edges, keeping the fixture near its configured size while exercising widget
 mounting, the spatial index, adjacency cleanup, and connection-scene
-invalidation. By default, it runs the same fixture and workloads in three
+invalidation. By default, it runs the same fixture and workloads in four
 configurations:
 
 - `full`: adaptive LOD disabled, so every visible node uses its full widget.
-- `navigation`: all 500 nodes use full widgets while idle, but camera gestures
+- `retained-full`: every node keeps full labels, card styling, and port marks,
+  but ordinary nodes are retained as recorded pictures instead of widget
+  subtrees. Active nodes are promoted back into the widget overlay.
+- `navigation`: all nodes use full widgets while idle, but camera gestures
   replace ordinary nodes with the painted scene. Selected or actively edited
   nodes remain promoted as a small widget overlay.
 - `adaptive`: adaptive LOD enabled with `maxInteractiveNodes: 200`, allowing
   the editor to switch to its batched overview painter.
 
-Run it from `packages/demo` on the target hardware in profile mode:
+Run it from `packages/demo` as the production web target:
 
 ```sh
 flutter drive \
-  --profile \
-  -d macos \
+  --release \
+  --wasm \
+  -d web-server \
+  --browser-name chrome \
+  --web-port 8080 \
   --driver=test_driver/integration_test.dart \
   --target=integration_test/node_flow_500_benchmark_test.dart
 ```
 
-Replace `macos` with another configured device ID. For the web target, use
-`-d chrome`. Keep the window size, device, Flutter version, renderer, and power
-state fixed when comparing runs.
+Keep the window size, Chrome version, Flutter version, renderer, and power state
+fixed when comparing runs. The report records `runtime.wasm`, which must be
+`true` for a valid WASM result.
 
 ## Local web release testing
 
@@ -54,27 +60,31 @@ cd packages/demo
 flutter drive \
   --release \
   --wasm \
-  -d chrome \
+  -d web-server \
+  --browser-name chrome \
+  --web-port 8080 \
   --driver=test_driver/integration_test.dart \
   --target=integration_test/node_flow_500_benchmark_test.dart \
   --dart-define=NODE_FLOW_BENCHMARK_RENDER_MODE=all
 ```
 
-Use `navigation` or `adaptive` instead of `all` to run one representation.
+Use `comparison` to run only the full-widget and retained-full representations,
+or name one representation directly.
 The automated driver opens a visible Chrome window, performs the workloads,
-writes `build/node_flow_500_benchmark.json`, and closes the window when done.
+writes `build/node_flow_<count>_benchmark.json`, and closes the window when done.
 
 The driver writes the structured result to
-`build/node_flow_500_benchmark.json`. The same report is also printed with a
-`NODE_FLOW_500_BENCHMARK` prefix. Each workload reports p50, p95, p99, and
+`build/node_flow_<count>_benchmark.json`. The same report is also printed with a
+`NODE_FLOW_BENCHMARK` prefix. Each workload reports p50, p95, p99, and
 maximum UI, raster, and total frame spans, plus the number of frames exceeding
-the 8.33 ms budget for a 120 Hz display. Warmup is captured as a separate
+the 16.67 ms budget for a 60 Hz display. Warmup is captured as a separate
 measurement phase, while pan, zoom, drag, and topology churn are marked as
 `steady_state`.
 Each phase reports requested versus engine-delivered frames, missing or extra
 timing records, delivery ratio, workload update counters, and frame-budget miss
-ratio. The existing `frame_count` and `frames_over_8_33_ms` fields remain as
-compatibility aliases. Each mode and scenario also records the effective LOD
+ratio. `frame_count` and the historical `frames_over_8_33_ms` metric remain for
+compatibility, while `frames_over_16_67_ms` is the current acceptance metric.
+Each mode and scenario also records the effective LOD
 level, widget/thumbnail path, spatially visible node count, and spatially
 visible connection count.
 
@@ -85,27 +95,52 @@ live-camera update before each requested frame; their
 `workload.viewport_updates` counter should therefore match
 `workload.pumped_frames`. The MobX/plugin viewport commits after each measured
 phase. The topology workload reports its add/remove API calls in
-`workload.graph_updates` and restores the original 500-node/955-edge fixture
+`workload.graph_updates` and restores the original configured fixture
 after measurement.
 
-To iterate on only one configuration, set `NODE_FLOW_BENCHMARK_RENDER_MODE` to
-`full`, `navigation`, or `adaptive` (`all` is the default):
+To compare the two full-detail renderers, set
+`NODE_FLOW_BENCHMARK_RENDER_MODE=comparison`. To iterate on one configuration,
+use `full`, `retained-full`, `navigation`, or `adaptive` (`all` is the default):
 
 ```sh
 flutter drive \
-  --profile \
-  -d macos \
+  --release \
+  --wasm \
+  -d web-server \
+  --browser-name chrome \
+  --web-port 8080 \
   --driver=test_driver/integration_test.dart \
   --target=integration_test/node_flow_500_benchmark_test.dart \
   --dart-define=NODE_FLOW_BENCHMARK_RENDER_MODE=adaptive
 ```
 
+Scale the same fixture to larger graphs without editing the benchmark:
+
+```sh
+flutter drive \
+  --release \
+  --wasm \
+  -d web-server \
+  --browser-name chrome \
+  --web-port 8080 \
+  --driver=test_driver/integration_test.dart \
+  --target=integration_test/node_flow_500_benchmark_test.dart \
+  --dart-define=NODE_FLOW_BENCHMARK_NODE_COUNT=2000 \
+  --dart-define=NODE_FLOW_BENCHMARK_RENDER_MODE=retained-full
+```
+
+The report is written to `build/node_flow_<count>_benchmark.json` and grouped
+under `node_flow_<count>`, so 500-, 1,000-, and 2,000-node runs can coexist.
+
 For a short diagnostic run while editing the harness, reduce the frame counts:
 
 ```sh
 flutter drive \
-  --profile \
-  -d macos \
+  --release \
+  --wasm \
+  -d web-server \
+  --browser-name chrome \
+  --web-port 8080 \
   --driver=test_driver/integration_test.dart \
   --target=integration_test/node_flow_500_benchmark_test.dart \
   --dart-define=NODE_FLOW_BENCHMARK_WARMUP_FRAMES=10 \
@@ -128,7 +163,7 @@ The relevant JSON shape for every phase is:
     "graph_updates": 0
   },
   "frame_budget": {
-    "target_ms": 8.333,
+    "target_ms": 16.667,
     "misses": 0,
     "met": 100,
     "miss_ratio": 0.0
@@ -141,12 +176,12 @@ The relevant JSON shape for every phase is:
 - This is a measurement harness, not a normal correctness test, so it has no
   hard timing assertions. Shared CI and debug-mode results are not stable FPS
   gates.
-- A 120 Hz target has an 8.33 ms total frame budget. Use a physical 120 Hz
-  display when validating that target; lower-refresh displays cannot prove it.
+- The acceptance target is 60 FPS, which gives the complete frame 16.67 ms.
+  Keep the test display and browser refresh rate fixed for comparisons.
 - The workloads call controller operations directly and therefore measure graph
   mutation, Flutter build/layout/paint, and raster work without pointer-event
   latency or hit-testing overhead. Input latency should be profiled separately.
-- The graph is intentionally zoomed so most or all 500 full node widgets are
+- The graph is intentionally zoomed so most or all configured full node widgets are
   visible. A smaller window can change the visible population and must be kept
   constant between comparisons.
 - Web engines can report raster timings differently or return zero for fields