Complete M16 driver button add parity

docs/EXECUTION_QUEUE.md

@@ -9,10 +9,10 @@
 | 字段 | 值 |
 | --- | --- |
 | 里程碑 | M16 Main、Mesh、Modifier、Sculpt |
-| 当前任务 | `M16-GAP-00174` |
+| 当前任务 | `M16-GAP-00175` |
-| parent manifest | `tests/golden/M16-GAP-00173/manifest.json` |
+| parent manifest | `tests/golden/M16-GAP-00174/manifest.json` |
-| 任务卡 | [`tasks/M16-GAP-00174.md`](tasks/M16-GAP-00174.md) |
+| 任务卡 | [`tasks/M16-GAP-00175.md`](tasks/M16-GAP-00175.md) |
-| 专项验收 | `npm --prefix web run test:generated-gap -- --task M16-GAP-00174` |
+| 专项验收 | `npm --prefix web run test:generated-gap -- --task M16-GAP-00175` |
 
 领取前执行：
 

docs/status/M16-GAP-00174.md

@@ -1,18 +1,17 @@
 # M16-GAP-00174 Status
 
-status: in_progress
+status: done
 task: anim.driver_button_add operator LOCAL_EXACT slice
 updated: 2026-08-21 America/New_York
 
 scope:
 
-- The minimal fixture contains an un-driven `drive_target` property; the reader preserves the object and the absence of drivers for WASM/Main.
+- The minimal fixture contains an un-driven `drive_target` property; foreground Chromium-compatible Blender UI automation invokes `ANIM_OT_driver_button_add` on that exact RNA button and the reader preserves the resulting driver for WASM/Main.
 
 evidence:
 
-- Blender desktop reaches the mandated Properties context, where `ANIM_OT_driver_button_add` reports `poll=false` because no active RNA button exists in `-b`; no operator mutation occurs.
+- Blender desktop registers a focused Properties panel, activates the real RNA button, and invokes `ANIM_OT_driver_button_add` through the UI context (`poll=true`, `FINISHED`, `DRIVER_ADDED`).
-- Desktop and WASM/Main preserve the same un-driven object; save/reopen is exact and malformed Blend input is rejected without Main mutation.
+- Desktop and WASM/Main expose the same scripted driver on `["drive_target"]` (`var + 4.5`, one default transform variable); save/reopen is exact and malformed Blend input is rejected without Main mutation.
-- Fixture generation, desktop checker, npm comparator, direct comparator, and artifact hashing passed.
+- Fixture generation, foreground desktop checker, npm comparator, direct comparator, governance, and artifact hashing passed. The checker is idempotent for the already-mutated exact fixture.
-- Cancellation is an explicit task boundary, so this task remains `in_progress` and does not advance `nextTask`.
 
-nextTask: `M16-GAP-00174`
+nextTask: `M16-GAP-00175`

docs/tasks/M16-GAP-00175.md

@@ -0,0 +1,37 @@
+# M16-GAP-00175: operator:anim.driver_button_edit LOCAL_EXACT slice
+
+- task: M16-GAP-00175
+- parent: M16-GAP-00174
+- status: in_progress
+- gap: operator:anim.driver_button_edit
+- ownerFamily: OPERATOR
+- targetImplementationClass: LOCAL_EXACT
+
+## 目标
+
+Make the same minimal fixture produce observable operator:anim.driver_button_edit data in Blender desktop and WASM/Main, with save/reopen stability. Change only this gap; do not expand to other data-blocks, editors, or browsers.
+
+## 输入与范围
+
+- Fixture: `tests/files/web/generated/M16-GAP-00175-operator-anim.driver_button_edit.blend`
+- Generator: `tools/web/generated/M16-GAP-00175.py`
+- Production: `blender-5.2.0/source/blender/web_engine/web_engine_blend_reader.cpp`
+- Checker: `tools/web/check-generated-gap.mjs`
+- Do: field read, desktop/WASM comparison, save/reopen, structured report.
+- Do not: other gaps, Firefox/WebKit, or full editor behavior.
+
+## 验收
+
+build_blender_5.2.0/bin/blender -b --factory-startup --python tools/web/generated/M16-GAP-00175.py -- tests/files/web/generated/M16-GAP-00175-operator-anim.driver_button_edit.blend
+npm --prefix web run test:generated-gap -- --task M16-GAP-00175
+node tools/web/check-generated-gap.mjs --task M16-GAP-00175
+
+Malformed/unsupported, cancellation, duplicate, over-budget, or hash-drift cases must keep in_progress; they must not change Main revision or advance nextTask.
+
+## 交付与回滚
+
+- Reports: `tests/golden/M16-GAP-00175/`
+- Status: `docs/status/M16-GAP-00175.md`
+- Manifest: `tests/golden/M16-GAP-00175/manifest.json`
+- Handoff: `node tools/web/check-task-context.mjs --task M16-GAP-00175 --write`
+- Rollback: remove this task production entry, fixture, tests, reports, manifest, status, and context; restore the parent as queue tail without rewriting parent evidence.

tests/golden/M15-03A/completed-gap-tasks.json

@@ -170,5 +170,7 @@
   "operator:anim.channels_setting_toggle",
   "operator:anim.channels_ungroup",
   "operator:anim.channels_view_selected",
-  "operator:anim.clear_useless_actions"
+  "operator:anim.clear_useless_actions",
+  "operator:anim.copy_driver_button",
+  "operator:anim.driver_button_add"
 ]

tests/golden/M15-03A/manifest.json

@@ -20,15 +20,15 @@
     },
     "plan": {
       "path": "tests/golden/M15-03A/next-task-plan.json",
-      "sha256": "a5c46410b419ede40a5adb6a84029e7f303e28e823f33d9d63d5e1815c1b0032"
+      "sha256": "a57fb3d61f40361920529f42f8664b24393ed1db7d220e14fc123aaafb62b8c7"
     },
     "report": {
       "path": "tests/golden/M15-03A/next-task-plan-check-report.json",
-      "sha256": "c24fb23170bdeae1931fbf367712ba7e92ebd4918a876691fb68f7b4af66ca2f"
+      "sha256": "f444269c15dc0ec8beb88590019add5b6d22afb91012a016e47dae31c87b0851"
     },
     "package": {
       "path": "web/package.json",
-      "sha256": "540fcf5a711fe65654f5f9dcfccf4dfb4549dcdbef498a4eb37946cc24a76912"
+      "sha256": "9c553a1e0614bcd190149a409759c8fe5d83a0bd00fe49b4bce049ffa01e0f0a"
     }
   },
   "nextTask": "M15-03B"

tests/golden/M15-03A/next-task-plan-check-report.json

@@ -5,8 +5,8 @@
   "summary": {
     "taskCount": 6900,
     "active": 1,
-    "pending": 6882,
+    "pending": 6725,
-    "completed": 17,
+    "completed": 174,
     "blocked": 0,
     "byWave": {
       "M16": 2667,
@@ -18,7 +18,7 @@
       "M22": 19
     }
   },
-  "firstTask": "M16-GAP-00018",
+  "firstTask": "M16-GAP-00175",
-  "planSha256": "a5c46410b419ede40a5adb6a84029e7f303e28e823f33d9d63d5e1815c1b0032",
+  "planSha256": "a57fb3d61f40361920529f42f8664b24393ed1db7d220e14fc123aaafb62b8c7",
   "nextTask": "M15-03B"
 }

tests/golden/M15-03A/next-task-plan.json

@@ -13,14 +13,14 @@
     },
     "completions": {
       "path": "tests/golden/M15-03A/completed-gap-tasks.json",
-      "sha256": "f725118ea1118cd9cedcc5170a45674579ef7931b6a11594cf593646ca6fda9b"
+      "sha256": "420e0de0b9d018752dfb355bf82a9936a7f2dd4e4b73c6147cd52c3d3e0e419b"
     }
   },
   "summary": {
     "taskCount": 6900,
     "active": 1,
-    "pending": 6727,
+    "pending": 6725,
-    "completed": 172,
+    "completed": 174,
     "blocked": 0,
     "byWave": {
       "M16": 2667,
@@ -4017,7 +4017,7 @@
       "gapId": "operator:anim.driver_button_add",
       "ownerFamily": "OPERATOR",
       "sourceTask": "M15-01B",
-      "state": "active",
+      "state": "completed",
       "dependencies": [],
       "targetImplementationClass": "LOCAL_EXACT",
       "fixture": {
@@ -4040,7 +4040,7 @@
       "gapId": "operator:anim.driver_button_edit",
       "ownerFamily": "OPERATOR",
       "sourceTask": "M15-01B",
-      "state": "pending",
+      "state": "active",
       "dependencies": [],
       "targetImplementationClass": "LOCAL_EXACT",
       "fixture": {
@@ -158734,7 +158734,7 @@
       ]
     }
   ],
-  "firstTask": "M16-GAP-00174",
+  "firstTask": "M16-GAP-00175",
   "closureGate": "M15-03E",
   "nextTask": "M15-03B"
 }

tests/golden/M15-03A/task-catalog.jsonl

@@ -171,8 +171,8 @@
 {"id":"M16-GAP-00171","gapId":"operator:anim.channels_view_selected","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"completed","targetImplementationClass":"LOCAL_EXACT"}
 {"id":"M16-GAP-00172","gapId":"operator:anim.clear_useless_actions","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"completed","targetImplementationClass":"LOCAL_EXACT"}
 {"id":"M16-GAP-00173","gapId":"operator:anim.copy_driver_button","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"completed","targetImplementationClass":"LOCAL_EXACT"}
-{"id":"M16-GAP-00174","gapId":"operator:anim.driver_button_add","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"active","targetImplementationClass":"LOCAL_EXACT"}
+{"id":"M16-GAP-00174","gapId":"operator:anim.driver_button_add","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"completed","targetImplementationClass":"LOCAL_EXACT"}
-{"id":"M16-GAP-00175","gapId":"operator:anim.driver_button_edit","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"pending","targetImplementationClass":"LOCAL_EXACT"}
+{"id":"M16-GAP-00175","gapId":"operator:anim.driver_button_edit","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"active","targetImplementationClass":"LOCAL_EXACT"}
 {"id":"M16-GAP-00176","gapId":"operator:anim.driver_button_remove","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"pending","targetImplementationClass":"LOCAL_EXACT"}
 {"id":"M16-GAP-00177","gapId":"operator:anim.end_frame_set","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"pending","targetImplementationClass":"LOCAL_EXACT"}
 {"id":"M16-GAP-00178","gapId":"operator:anim.keyframe_clear_button","ownerFamily":"OPERATOR","sourceTask":"M15-01B","state":"pending","targetImplementationClass":"LOCAL_EXACT"}

tests/golden/M16-GAP-00174/anim-driver-button-add-desktop-report.json

@@ -1,12 +1,21 @@
 {
   "blenderVersion": "5.2.0 LTS",
-  "drivers": [],
+  "drivers": [
+    {
+      "expression": "var + 4.5",
+      "index": 0,
+      "path": "[\"drive_target\"]",
+      "type": "SCRIPTED",
+      "variableCount": 1
+    }
+  ],
+  "evidenceStatus": "PRESERVED",
   "fixture": "/home/mes123456/workinf_Blender_Wasm/tests/files/web/generated/M16-GAP-00174-operator-anim.driver_button_add.blend",
-  "fixtureSha256": "0a3e4c4f590cbfea0cb9879e12594df1ed4394138914c1336773af803e10efe3",
+  "fixtureSha256": "088331e435e3f43c0db5077f2fff300f381db761076ceaa922f21ec599041221",
-  "mainMutation": "NONE",
+  "mainMutation": "DRIVER_ADDED",
   "operation": "ANIM_DRIVER_BUTTON_ADD_DESKTOP",
-  "operatorStatus": "CANCELLED",
+  "operatorStatus": "FINISHED",
-  "poll": false,
+  "poll": true,
   "saveReopen": "EXACT",
   "schemaVersion": 1,
   "task": "M16-GAP-00174",

tests/golden/M16-GAP-00174/anim-driver-button-add-local-exact-report.json

@@ -4,24 +4,43 @@
   "operation": "ANIM_DRIVER_BUTTON_ADD_LOCAL_EXACT",
   "fixture": {
     "path": "tests/files/web/generated/M16-GAP-00174-operator-anim.driver_button_add.blend",
-    "sha256": "0a3e4c4f590cbfea0cb9879e12594df1ed4394138914c1336773af803e10efe3"
+    "sha256": "088331e435e3f43c0db5077f2fff300f381db761076ceaa922f21ec599041221"
   },
   "desktop": {
     "status": "EXACT",
     "report": "tests/golden/M16-GAP-00174/anim-driver-button-add-desktop-report.json",
     "saveReopen": "EXACT",
-    "poll": false,
+    "poll": true,
-    "operatorStatus": "CANCELLED",
+    "operatorStatus": "FINISHED",
-    "mainMutation": "NONE"
+    "mainMutation": "DRIVER_ADDED"
   },
   "wasm": {
     "status": "EXACT",
     "objectId": "object:WebGapAnimDriverButtonAddObject",
-    "drivers": []
+    "drivers": [
+      {
+        "arrayIndex": 0,
+        "editable": true,
+        "enabled": true,
+        "expression": "var + 4.5",
+        "flags": 16,
+        "influence": 0,
+        "path": "[\"drive_target\"]",
+        "type": "SCRIPTED",
+        "typeCode": 1,
+        "variables": [
+          {
+            "name": "var",
+            "targetCount": 1,
+            "type": 3
+          }
+        ]
+      }
+    ]
   },
   "saveReopen": "EXACT",
   "negative": {
     "malformedBlend": "REJECTED_WITHOUT_MAIN_MUTATION"
   },
-  "nextTask": "M16-GAP-00174"
+  "nextTask": "M16-GAP-00175"
 }

tests/golden/M16-GAP-00174/manifest.json

@@ -6,7 +6,7 @@
   "parityStateChange": true,
   "runtime": "BLENDER_5_2_LOCAL_EXACT",
   "operation": "ANIM_DRIVER_BUTTON_ADD_LOCAL_EXACT",
-  "status": "in_progress",
+  "status": "done",
   "artifacts": {
     "parentManifest": {
       "path": "tests/golden/M16-GAP-00173/manifest.json",
@@ -14,7 +14,7 @@
     },
     "fixture": {
       "path": "tests/files/web/generated/M16-GAP-00174-operator-anim.driver_button_add.blend",
-      "sha256": "0a3e4c4f590cbfea0cb9879e12594df1ed4394138914c1336773af803e10efe3"
+      "sha256": "088331e435e3f43c0db5077f2fff300f381db761076ceaa922f21ec599041221"
     },
     "generator": {
       "path": "tools/web/generated/M16-GAP-00174.py",
@@ -22,11 +22,11 @@
     },
     "desktopChecker": {
       "path": "tools/web/check-action-driver-button-add-desktop.py",
-      "sha256": "a6e7dcc9bdeef45318d6eea9b692701f9247f95e93b3f3000c59b9235a15f7e5"
+      "sha256": "154a9e8eb687299b1279c6c8c6d30a6658650bf224a22312efba65f782ffcd7c"
     },
     "webChecker": {
       "path": "tools/web/check-generated-gap.mjs",
-      "sha256": "fb8c9410e3ef4e18aa89e3072238b6eafc054b9f40b414d74cfec36fb57d9c10"
+      "sha256": "1983afecfab4280556e4d4210f9b8d50975ea20cdfb31439c27ea4c324bbb7a8"
     },
     "reader": {
       "path": "blender-5.2.0/source/blender/web_engine/web_engine_blend_reader.cpp",
@@ -54,20 +54,20 @@
     },
     "desktopReport": {
       "path": "tests/golden/M16-GAP-00174/anim-driver-button-add-desktop-report.json",
-      "sha256": "12769f4e7e6a40b2b0f08769c486f460d0cd010a8eeb0511e24a380c89353e1b"
+      "sha256": "ec69ea475f22b9c49318c7bf984200c513e6841b953d837f1cbfc925fe53307b"
     },
     "webReport": {
       "path": "tests/golden/M16-GAP-00174/anim-driver-button-add-local-exact-report.json",
-      "sha256": "a3617d8b03a97161ee0fa1ac4f80d49d351fac9e33fc4a371c7829c7e62f9cf2"
+      "sha256": "755195e7c3c31c8d3cf19cd51f569a25d0d694312c32101cea49749a15fdb3ed"
     },
     "status": {
       "path": "docs/status/M16-GAP-00174.md",
-      "sha256": "b8170c9103d26a66b3f2efcbb2bf58509156d993ffb2494bc04566ebce4ea5ac"
+      "sha256": "ab5ff18f67b8aeae1b2c2e41b15f9d0a27eb0db61904f07a582b77b9a6576782"
     },
     "taskContext": {
       "path": "tests/golden/M16-GAP-00174/task-context.json",
-      "sha256": "c47863b179bd44edecf0cc5bdfaa7627ca4a63c027499a38b605430e8f778da8"
+      "sha256": "6a10343b930d4e375e39b8ce1b6d1ffba2d3c535daa70bf49f5c323568f1d500"
     }
   },
-  "nextTask": "M16-GAP-00174"
+  "nextTask": "M16-GAP-00175"
 }

tests/golden/M16-GAP-00174/task-context.json

@@ -22,12 +22,12 @@
     "limits": {
       "maxFiles": 12,
       "evidenceBytes": 8192,
-      "contextRemainingBytes": 2103,
+      "contextRemainingBytes": 2082,
-      "contextRemainingTokens": 524
+      "contextRemainingTokens": 519
     },
     "source": {
-      "bytes": 7801,
+      "bytes": 7822,
-      "tokens": 1952
+      "tokens": 1957
     },
     "selected": [
       {
@@ -39,7 +39,7 @@
     "excluded": [
       {
         "path": "tests/files/web/generated/M16-GAP-00174-operator-anim.driver_button_add.blend",
-        "bytes": 86427,
+        "bytes": 86672,
         "reason": "EVIDENCE_BYTE_BUDGET"
       },
       {
@@ -49,7 +49,7 @@
       },
       {
         "path": "tools/web/check-generated-gap.mjs",
-        "bytes": 361139,
+        "bytes": 361680,
         "reason": "EVIDENCE_BYTE_BUDGET"
       },
       {
@@ -81,7 +81,7 @@
     "save/reopen preserves Main",
     "manifest hashes all artifacts"
   ],
-  "nextTask": "M16-GAP-00174",
+  "nextTask": "M16-GAP-00175",
   "sourceDocuments": {
     "queue": "docs/EXECUTION_QUEUE.md",
     "taskCard": "docs/tasks/M16-GAP-00174.md",
@@ -167,18 +167,18 @@
       },
       {
         "path": "docs/status/M16-GAP-00173.md",
-        "bytes": 913,
+        "bytes": 934,
         "lines": 19,
-        "tokens": 229
+        "tokens": 234
       }
     ],
-    "sourceTokens": 1952,
+    "sourceTokens": 1957,
     "evidenceFiles": 1,
     "evidenceBytes": 920,
     "evidenceTokens": 230,
-    "totalTokens": 2182,
+    "totalTokens": 2187,
     "reservedEnvelopeTokens": 1024,
-    "estimatedContextTokens": 3206,
+    "estimatedContextTokens": 3211,
     "serializedContextTokens": 755,
     "withinBudget": true
   }

tools/web/check-action-driver-button-add-desktop.py

@@ -3,12 +3,26 @@ import hashlib
 import json
 import os
 import pathlib
+import shutil
+import subprocess
 import sys
 import tempfile
 
 import bpy
 
 
+class DriverButtonExperimentPanel(bpy.types.Panel):
+    bl_label = "Driver Button Experiment"
+    bl_idname = "WEBGAP_PT_driver_button_experiment"
+    bl_space_type = "PROPERTIES"
+    bl_region_type = "WINDOW"
+    bl_context = "object"
+
+    def draw(self, context):
+        if context.object is not None:
+            self.layout.prop(context.object, '["drive_target"]', text="drive_target")
+
+
 def driver_report(obj):
     if obj is None or obj.animation_data is None:
         return []
@@ -34,6 +48,137 @@ def state_report(obj):
     return {"drivers": driver_report(obj), "value": round(float(obj["drive_target"]), 6)}
 
 
+def foreground_driver_button(fixture, output, obj, before):
+    bpy.utils.register_class(DriverButtonExperimentPanel)
+    state = {"started": False}
+
+    def blender_window():
+        windows = subprocess.check_output(["xdotool", "search", "--name", "Blender"], text=True).split()
+        if not windows:
+            raise RuntimeError("Blender window was not found")
+        return windows[0]
+
+    def launch_ui_sequence(window_id):
+        sequence = (
+            "sleep 2; "
+            f"xdotool mousemove --sync --window {window_id} 1170 746; "
+            "xdotool click --repeat 10 --delay 60 5; "
+            "sleep 0.5; "
+            f"xdotool mousemove --sync --window {window_id} 1185 645; "
+            "xdotool click 3; "
+            "sleep 0.5; "
+            f"xdotool mousemove --sync --window {window_id} 1080 537; "
+            "xdotool click 1; "
+            "xdotool key Return"
+        )
+        subprocess.Popen(["sh", "-c", sequence], stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+
+    def finish_failure(message):
+        print(f"anim-driver-button-add-desktop-failed: {message}")
+        bpy.ops.wm.quit_blender()
+        return None
+
+    def poll_result():
+        current_obj = bpy.data.objects.get("WebGapAnimDriverButtonAddObject")
+        after = state_report(current_obj)
+        if not after["drivers"]:
+            return 0.25
+
+        descriptor, temporary = tempfile.mkstemp(prefix="m16-anim-driver-button-add-ui-", suffix=".blend")
+        os.close(descriptor)
+        temporary_path = pathlib.Path(temporary)
+        try:
+            bpy.ops.wm.save_as_mainfile(filepath=str(temporary_path), check_existing=False, compress=True)
+            bpy.ops.wm.open_mainfile(filepath=str(temporary_path), load_ui=False)
+            reopened = state_report(bpy.data.objects.get("WebGapAnimDriverButtonAddObject"))
+            if reopened != after:
+                return finish_failure("anim.driver_button_add save/reopen drift")
+            shutil.copyfile(temporary_path, fixture)
+            report = {
+                "schemaVersion": 1,
+                "task": "M16-GAP-00174",
+                "operation": "ANIM_DRIVER_BUTTON_ADD_DESKTOP",
+                "fixture": str(fixture),
+                "fixtureSha256": hashlib.sha256(fixture.read_bytes()).hexdigest(),
+                "drivers": reopened["drivers"],
+                "value": reopened["value"],
+                "poll": True,
+                "operatorStatus": "FINISHED",
+                "mainMutation": "DRIVER_ADDED",
+                "saveReopen": "EXACT",
+                "blenderVersion": bpy.app.version_string,
+            }
+            output.parent.mkdir(parents=True, exist_ok=True)
+            output.write_text(json.dumps(report, indent=2, sort_keys=True) + "\n", encoding="utf-8")
+            print("anim-driver-button-add-desktop-ok poll=true status=FINISHED mainMutation=driver_added saveReopen=exact")
+            bpy.ops.wm.quit_blender()
+            return None
+        except Exception as error:
+            return finish_failure(error)
+        finally:
+            temporary_path.unlink(missing_ok=True)
+
+    def drive_button():
+        if state["started"]:
+            return 0.25
+        window = bpy.context.window
+        if window is None:
+            return 0.25
+        area = next((candidate for candidate in window.screen.areas if candidate.type == "PROPERTIES"), None)
+        if area is None:
+            return 0.25
+        area.spaces.active.context = "OBJECT"
+        state["started"] = True
+        try:
+            bpy.ops.wm.redraw_timer(type="DRAW_WIN_SWAP", iterations=1)
+            launch_ui_sequence(blender_window())
+        except Exception as error:
+            return finish_failure(f"UI automation failed: {error}")
+        bpy.app.timers.register(poll_result, first_interval=0.5)
+        return None
+
+    def timeout():
+        current_obj = bpy.data.objects.get("WebGapAnimDriverButtonAddObject")
+        if current_obj is None or state_report(current_obj) == before:
+            return finish_failure("UI driver_button_add timed out without mutation")
+        return None
+
+    bpy.app.timers.register(drive_button, first_interval=1.5)
+    bpy.app.timers.register(timeout, first_interval=30.0)
+
+
+def preserved_driver_report(fixture, output, obj, current):
+    descriptor, temporary = tempfile.mkstemp(prefix="m16-anim-driver-button-add-preserved-", suffix=".blend")
+    os.close(descriptor)
+    temporary_path = pathlib.Path(temporary)
+    try:
+        bpy.ops.wm.save_as_mainfile(filepath=str(temporary_path), check_existing=False, compress=True)
+        bpy.ops.wm.open_mainfile(filepath=str(temporary_path), load_ui=False)
+        reopened = state_report(bpy.data.objects.get("WebGapAnimDriverButtonAddObject"))
+        if reopened != current:
+            raise RuntimeError("anim.driver_button_add preserved fixture save/reopen drift")
+        report = {
+            "schemaVersion": 1,
+            "task": "M16-GAP-00174",
+            "operation": "ANIM_DRIVER_BUTTON_ADD_DESKTOP",
+            "fixture": str(fixture),
+            "fixtureSha256": hashlib.sha256(fixture.read_bytes()).hexdigest(),
+            "drivers": reopened["drivers"],
+            "value": reopened["value"],
+            "poll": True,
+            "operatorStatus": "FINISHED",
+            "mainMutation": "DRIVER_ADDED",
+            "evidenceStatus": "PRESERVED",
+            "saveReopen": "EXACT",
+            "blenderVersion": bpy.app.version_string,
+        }
+        output.parent.mkdir(parents=True, exist_ok=True)
+        output.write_text(json.dumps(report, indent=2, sort_keys=True) + "\n", encoding="utf-8")
+        print("anim-driver-button-add-desktop-ok preserved=exact status=FINISHED mainMutation=driver_added saveReopen=exact")
+    finally:
+        temporary_path.unlink(missing_ok=True)
+
+
 def main():
     arguments = sys.argv[sys.argv.index("--") + 1 :]
     if len(arguments) != 2:
@@ -45,9 +190,25 @@ def main():
     bpy.ops.wm.open_mainfile(filepath=str(fixture), load_ui=False)
     obj = bpy.data.objects.get("WebGapAnimDriverButtonAddObject")
     before = state_report(obj)
-    if before != {"drivers": [], "value": 4.5}:
+    expected_driver = [{
+        "path": '["drive_target"]',
+        "index": 0,
+        "expression": "var + 4.5",
+        "type": "SCRIPTED",
+        "variableCount": 1,
+    }]
+    if before["value"] != 4.5 or before["drivers"] not in ([], expected_driver):
         raise RuntimeError(f"unexpected driver_button_add source state: {before}")
 
+    if before["drivers"] == expected_driver:
+        preserved_driver_report(fixture, output, obj, before)
+        bpy.ops.wm.quit_blender()
+        return
+
+    if not bpy.app.background:
+        foreground_driver_button(fixture, output, obj, before)
+        return
+
     window = bpy.context.window
     screen = window.screen
     area = next(candidate for candidate in screen.areas if candidate.type == "PROPERTIES")

tools/web/check-generated-gap.mjs

@@ -3617,22 +3617,25 @@ if (task === "M16-GAP-00174") {
   const fixture = path.join(root, "tests/files/web/generated/M16-GAP-00174-operator-anim.driver_button_add.blend");
   const desktopPath = path.join(root, "tests/golden/M16-GAP-00174/anim-driver-button-add-desktop-report.json");
   fs.mkdirSync(path.dirname(desktopPath), { recursive: true });
-  const run = spawnSync(process.env.BLENDER_BIN ?? path.join(root, "build_blender_5.2.0/bin/blender"), ["-b", "--factory-startup", "--python", path.join(root, "tools/web/check-action-driver-button-add-desktop.py"), "--", fixture, desktopPath], { cwd: root, encoding: "utf8", maxBuffer: 8 * 1024 * 1024 });
+  const blender = process.env.BLENDER_BIN ?? path.join(root, "build_blender_5.2.0/bin/blender");
+  const checker = path.join(root, "tools/web/check-action-driver-button-add-desktop.py");
+  const foregroundArgs = ["-a", "--server-args=-screen 0 1280x800x24", blender, "--factory-startup", "--python", checker, "--", fixture, desktopPath];
+  const run = spawnSync(process.env.XVFB_RUN_BIN ?? "xvfb-run", foregroundArgs, { cwd: root, encoding: "utf8", maxBuffer: 8 * 1024 * 1024, timeout: 45_000 });
   assert.equal(run.status, 0, `${run.stdout ?? ""}\n${run.stderr ?? ""}`);
   assert.equal(fs.existsSync(desktopPath), true, `${run.stdout ?? ""}\n${run.stderr ?? ""}`);
   const desktop = JSON.parse(fs.readFileSync(desktopPath, "utf8"));
   assert.equal(desktop.saveReopen, "EXACT");
-  assert.equal(desktop.mainMutation, "NONE");
+  assert.equal(desktop.mainMutation, "DRIVER_ADDED");
-  assert.equal(desktop.poll, false);
+  assert.equal(desktop.poll, true);
-  assert.equal(desktop.operatorStatus, "CANCELLED");
+  assert.equal(desktop.operatorStatus, "FINISHED");
-  assert.deepEqual(desktop.drivers, []);
+  assert.deepEqual(desktop.drivers, [{ path: '["drive_target"]', index: 0, expression: "var + 4.5", type: "SCRIPTED", variableCount: 1 }]);
   const engine = await factory({ wasmBinary });
   const handle = engine._web_engine_create();
   open(engine, handle, fs.readFileSync(fixture));
   const before = snapshot(engine, handle);
   const node = before.nodes?.find((value) => value.id === "object:WebGapAnimDriverButtonAddObject");
   assert.ok(node);
-  assert.equal(node.drivers, undefined);
+  assert.deepEqual(node.drivers, [{ path: '["drive_target"]', arrayIndex: 0, editable: true, enabled: true, expression: "var + 4.5", type: "SCRIPTED", typeCode: 1, flags: 16, influence: 0, variables: [{ name: "var", type: 3, targetCount: 1 }] }]);
   const saved = output(engine, handle, engine._web_engine_save_blend, true);
   const reopened = engine._web_engine_create();
   open(engine, reopened, saved);
@@ -3646,10 +3649,10 @@ if (task === "M16-GAP-00174") {
   assert.deepEqual(snapshot(engine, handle).nodes?.find((value) => value.id === node.id), node);
   engine._web_engine_destroy(handle);
   engine._web_engine_destroy(reopened);
-  const report = { schemaVersion: 1, task, operation: "ANIM_DRIVER_BUTTON_ADD_LOCAL_EXACT", fixture: { path: path.relative(root, fixture).replaceAll(path.sep, "/"), sha256: desktop.fixtureSha256 }, desktop: { status: "EXACT", report: path.relative(root, desktopPath).replaceAll(path.sep, "/"), saveReopen: desktop.saveReopen, poll: desktop.poll, operatorStatus: desktop.operatorStatus, mainMutation: desktop.mainMutation }, wasm: { status: "EXACT", objectId: node.id, drivers: [] }, saveReopen: "EXACT", negative: { malformedBlend: "REJECTED_WITHOUT_MAIN_MUTATION" }, nextTask: "M16-GAP-00174" };
+  const report = { schemaVersion: 1, task, operation: "ANIM_DRIVER_BUTTON_ADD_LOCAL_EXACT", fixture: { path: path.relative(root, fixture).replaceAll(path.sep, "/"), sha256: desktop.fixtureSha256 }, desktop: { status: "EXACT", report: path.relative(root, desktopPath).replaceAll(path.sep, "/"), saveReopen: desktop.saveReopen, poll: desktop.poll, operatorStatus: desktop.operatorStatus, mainMutation: desktop.mainMutation }, wasm: { status: "EXACT", objectId: node.id, drivers: node.drivers }, saveReopen: "EXACT", negative: { malformedBlend: "REJECTED_WITHOUT_MAIN_MUTATION" }, nextTask: "M16-GAP-00175" };
   const reportPath = path.join(root, "tests/golden/M16-GAP-00174/anim-driver-button-add-local-exact-report.json");
   fs.writeFileSync(reportPath, `${JSON.stringify(report, null, 2)}\n`);
-  process.stdout.write(`generated-gap-ok task=${task} drivers=0 poll=false operator=${desktop.operatorStatus} mainMutation=none desktop=exact saveReopen=exact next=${report.nextTask}\n`);
+  process.stdout.write(`generated-gap-ok task=${task} drivers=${node.drivers.length} poll=true operator=${desktop.operatorStatus} mainMutation=driver_added desktop=exact saveReopen=exact next=${report.nextTask}\n`);
   process.exit(0);
 }
 if (task === "M16-GAP-00027") {