Add whiteboard primitive screenshot proof gate

docs/en/phase-0-reactflow-parity-audit.md

@@ -242,6 +242,10 @@ Phase 548 is GitHub #219 / `avalonia-node-map-10p`, the first whiteboard primiti
 
 Phase 549 is GitHub #221 / `avalonia-node-map-3l6`, the whiteboard primitive persistence decision implementation gate. This internal Core policy slice records `WHITEBOARD_PRIMITIVE_PERSISTENCE_DECISION_GATE`: `GraphWhiteboardPrimitivePersistenceDecision` chooses a separate annotation surface and `ExcludedFromCurrentGraphDocumentSchema` for current whiteboard primitives, while keeping `GraphDocumentCompatibility`, `GraphDocumentSerializer`, and `CurrentSchemaVersion` graph-document scoped. The contract lists migration policy, compatibility tests, workspace persistence boundary tests, clipboard fragment boundary tests, and screenshot artifact boundary tests as required before any future GraphDocument schema change. Phase 549 is stacked after PR #220 and must not merge before Phase 548. It authorizes no GraphDocument schema change, no schema version bump, no workspace persistence behavior change, no public drawing API, no Avalonia pointer coordinator edits, no toolbar/tool activation, no eraser behavior, no screenshot manifest expansion, no Cookbook visual proof implementation, no UI redesign, no retained API removal, and no full React Flow whiteboard parity.
 
+## Phase 550 Update
+
+Phase 550 is GitHub #223 / `avalonia-node-map-wjr`, the whiteboard primitive Cookbook screenshot implementation gate. This proof-only Demo/Cookbook slice records `WHITEBOARD_PRIMITIVE_COOKBOOK_SCREENSHOT_GATE`: `cookbook-whiteboard-primitive-screenshot-proof` and `shell-cookbook-whiteboard-primitive-screenshot-proof` reuse `selection-marquee-workbench` to provide whiteboard primitive visual proof with route metadata, shell state, and non-overlap evidence after the internal model, renderer adapter, and persistence decision gates. Phase 550 is stacked after PR #222 and must not merge before Phase 549. It authorizes no public drawing API, no pointer coordinator, no toolbar, no eraser, no persisted whiteboard primitive state, no GraphDocument schema change, no renderer rewrite, no UI redesign, no retained API removal, and no full React Flow whiteboard parity.
+
 ## Phase 489 Update
 
 Phase 489 closed GitHub #101 / `avalonia-node-map-6sc` through PR #102 as a renderer virtualization design spike on branch `perf/renderer-virtualization-spike`. This slice was docs/tests only: it defined the proof contract required before any future ItemsRepeater/Skia-style renderer virtualization, background graph index, or graph-size claim expansion. It made no public API change and no runtime change. The current evidence remains viewport-budgeted scene projection/rendering, not a true renderer virtualization contract; `xlarge` stays telemetry-only.
@@ -573,6 +577,8 @@ Phase 548 records the whiteboard primitive renderer adapter skeleton through Git
 
 Phase 549 records the whiteboard primitive persistence decision implementation gate through GitHub #221 / `avalonia-node-map-3l6`. It adds only the internal `GraphWhiteboardPrimitivePersistenceDecision` policy contract: current whiteboard primitives use a separate annotation surface, remain `ExcludedFromCurrentGraphDocumentSchema`, and do not change `GraphDocumentCompatibility`, `GraphDocumentSerializer`, `CurrentSchemaVersion`, workspace persistence, clipboard fragments, screenshot artifacts, or public drawing APIs.
 
+Phase 550 records the whiteboard primitive Cookbook screenshot implementation gate through GitHub #223 / `avalonia-node-map-wjr`. It adds only the proof route/state pair `cookbook-whiteboard-primitive-screenshot-proof` and `shell-cookbook-whiteboard-primitive-screenshot-proof`, plus route metadata, shell state, and non-overlap visual proof for existing internal whiteboard primitive decisions; public drawing APIs, pointer coordinators, toolbar work, eraser behavior, persisted whiteboard primitive state, GraphDocument schema changes, renderer rewrites, UI redesign, and full React Flow whiteboard parity remain out of scope.
+
 | GitHub | Bead | Title | Priority | Likely write set | Parallelism |
 | --- | --- | --- | --- | --- | --- |
 | #193 | `avalonia-node-map-8l6` | Phase 535: refresh post-lasso visual feedback parity queue | P2 | parity roadmap docs and focused docs tests | Current docs/test queue refresh. Blocks the next implementation wave because it replaces the stale Phase 534 current row with tracker-backed follow-ups. |
@@ -590,7 +596,7 @@ Phase 549 records the whiteboard primitive persistence decision implementation g
 | #217 | `avalonia-node-map-rs0` | Phase 547: whiteboard primitive model skeleton | P2 | Core/Editor primitive model tests, internal model types, and renderer-neutral contract docs | Stacked after PR #216; do not merge before Phase 546. This slice adds the internal model skeleton only and must not touch renderer adapters, persistence/schema, pointer coordinators, screenshot manifests, toolbar UX, or eraser behavior. |
 | #219 | `avalonia-node-map-10p` | Phase 548: whiteboard primitive renderer adapter skeleton | P2 | renderer adapter tests, scene snapshot projection proof, and topmost primitive hit-testing evidence | Stacked after PR #218; do not merge before Phase 547. Must keep persistence/schema, Cookbook screenshot rows, pointer coordinators, and toolbar activation out of scope. |
 | #221 | `avalonia-node-map-3l6` | Phase 549: whiteboard primitive persistence decision implementation gate | P3 | persistence decision tests, schema/surface choice, migration criteria, and compatibility coverage | Stacked after PR #220; do not merge before Phase 548. Chooses separate annotation surface and keeps GraphDocument schema/version/workspace persistence unchanged before any saved whiteboard primitive claim. |
-| TBD | TBD | Phase 550: whiteboard primitive Cookbook screenshot implementation gate | P3 | Cookbook screenshot implementation gate docs/tests, route metadata, shell state, and non-overlap visual proof | Candidate after model, renderer, and persistence decisions. Must add visual proof before any whiteboard visual parity claim. |
+| #223 | `avalonia-node-map-wjr` | Phase 550: whiteboard primitive Cookbook screenshot implementation gate | P3 | Cookbook screenshot implementation gate docs/tests, route metadata, shell state, and non-overlap visual proof | Stacked after PR #222; do not merge before Phase 549. Adds the whiteboard primitive visual proof route/state pair only, with no public drawing API, pointer coordinator, toolbar, eraser, persisted whiteboard primitive state, GraphDocument schema change, renderer rewrite, UI redesign, or full whiteboard parity claim. |
 
 ## Recommended Parallel Worktree Plan
 
@@ -706,4 +712,6 @@ Current coverage includes scene-level route captures plus ten manifest-driven fu
 - Phase 546 is GitHub #215 / `avalonia-node-map-0l9`; it records the post-Phase-545 whiteboard implementation queue refresh and `WHITEBOARD_POST_GATE_QUEUE_REFRESH` without runtime behavior changes, public API changes, production model/schema changes, renderer-layer changes, screenshot manifest expansion, pointer coordinator edits, UI redesign, drawing tool implementation, eraser behavior, toolbar work, retained API removal, or full React Flow whiteboard parity.
 - Phase 547 is GitHub #217 / `avalonia-node-map-rs0`; it records `WHITEBOARD_PRIMITIVE_MODEL_SKELETON` with internal Core model types and focused Core/Editor contract tests only. Renderer adapters, persistence/schema, pointer coordinators, toolbar/tool activation, eraser behavior, screenshot manifests, Cookbook visual proof, public API claim expansion, retained API removal, and full React Flow whiteboard parity remain out of scope.
 - Phase 548 is GitHub #219 / `avalonia-node-map-10p`; it records `WHITEBOARD_PRIMITIVE_RENDERER_ADAPTER_SKELETON` with internal Core renderer-neutral projection and hit-testing tests only. GraphDocument schema changes, public drawing API, Avalonia renderer rewrites, NodeCanvasConnectionSceneRenderer edits, pointer coordinators, toolbar/tool activation, eraser behavior, persistence/schema work, screenshot manifests, Cookbook visual proof, retained API removal, and full React Flow whiteboard parity remain out of scope.
-- Product code remains out of scope for Phase 478, Phase 484, Phase 490, Phase 491, Phase 492, Phase 493, Phase 494, Phase 495, Phase 497, Phase 498, Phase 499, Phase 500, Phase 501, Phase 502, Phase 503, Phase 504, Phase 505, Phase 506, Phase 507, Phase 508, Phase 509, Phase 510, Phase 511, Phase 512, Phase 513, Phase 520, Phase 521, Phase 522, Phase 523, Phase 524, Phase 525, Phase 526, Phase 527, Phase 528, Phase 529, Phase 535, Phase 539, Phase 540, Phase 541, and Phase 546 unless a focused test proves a specific missing contract.
+- Phase 549 is GitHub #221 / `avalonia-node-map-3l6`; it records `WHITEBOARD_PRIMITIVE_PERSISTENCE_DECISION_GATE` with the internal `GraphWhiteboardPrimitivePersistenceDecision` policy contract only. GraphDocument schema changes, schema version bumps, workspace persistence behavior changes, public drawing APIs, pointer coordinators, toolbar/tool activation, eraser behavior, screenshot manifest expansion, UI redesign, retained API removal, and full React Flow whiteboard parity remain out of scope.
+- Phase 550 is GitHub #223 / `avalonia-node-map-wjr`; it records `WHITEBOARD_PRIMITIVE_COOKBOOK_SCREENSHOT_GATE` with `cookbook-whiteboard-primitive-screenshot-proof`, `shell-cookbook-whiteboard-primitive-screenshot-proof`, route metadata, shell state, non-overlap visual proof, and `WHITEBOARD_PRIMITIVE_SCREENSHOT_GATE_OK` only. Public drawing APIs, pointer coordinators, toolbar work, eraser behavior, persisted whiteboard primitive state, GraphDocument schema changes, renderer rewrites, UI redesign, retained API removal, and full React Flow whiteboard parity remain out of scope.
+- Product code remains out of scope for Phase 478, Phase 484, Phase 490, Phase 491, Phase 492, Phase 493, Phase 494, Phase 495, Phase 497, Phase 498, Phase 499, Phase 500, Phase 501, Phase 502, Phase 503, Phase 504, Phase 505, Phase 506, Phase 507, Phase 508, Phase 509, Phase 510, Phase 511, Phase 512, Phase 513, Phase 520, Phase 521, Phase 522, Phase 523, Phase 524, Phase 525, Phase 526, Phase 527, Phase 528, Phase 529, Phase 535, Phase 539, Phase 540, Phase 541, Phase 546, and Phase 550 unless a focused test proves a specific missing contract.