Document current Frame panel layout API limits

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+- Recheck saved spatial layouts on SteamOS 0.5.6 / SteamVR 2.18.2 (issue #31).
+  Read-only probes expose some panel geometry, but safe restoration of
+  Steam/gamescope docking and positions remains unverified. Record exact API
+  results and a reproducible probe; saved layouts remain unavailable.
+
 - Record packaged v0.4.17 Desktop Capture succeeding on a mapped nested KDE
   compositor on a real Frame with SteamOS 0.5.6. Headset overlay visibility was
   not established; this is evidence, not a new fix or resolution of issue #73.

docs/evidence/panel-layout-2026-10-24.md

@@ -0,0 +1,168 @@
+# Saved panel layouts: feasibility recheck, 2026-10-24
+
+Issue: [#31](https://github.com/saphid/frame-control/issues/31). Base: main
+`5b47cd3`. This investigation covers spatial save/restore for existing
+Steam/gamescope panels without another overlay application.
+
+## Decision and user behavior
+
+Keep saved layouts unavailable. The current Frame exposes some geometry,
+including a standing-space coordinate transform, but this investigation did
+not establish a complete dock-state snapshot or a controlled restore path for
+these panels. The existing companion/headset switcher still lists panels and
+requests focus; users arrange them with SteamVR's dashboard controls. No layout
+file, new control, overlay application or background service is added.
+
+This is a limit of the investigated route, not proof that every native
+implementation is impossible. In particular, failure of
+`GetOverlayTransformAbsolute` does **not** mean all pose readback is denied.
+
+## Device and read-only results
+
+SteamOS **0.5.6**, BUILD_ID **20261015.6141207**; `vrcmd --version`:
+**2.18.2**. `gamescope-session.service` was active and
+`plasma-workspace.target` inactive: Game Mode. gamescope used the OpenVR backend
+and `--virtual-connector-strategy PerAppId`. Battery was 99%, Not charging,
+before the probe and 100%, Full, afterwards.
+
+The [exact probe](panel-layout-2026-10-24/probe.py) loads only
+`FnTable:IVROverlay_028` from the shipped
+`/opt/steamvr/bin/linuxarm64/libopenvr_api.so`. It uses application type 3
+(`VRApplication_Background`, avoiding runtime startup) and shuts down its own
+OpenVR connection in `finally`. Initialization and interface acquisition both
+returned 0. It calls getters only, with no image capture or input injection.
+
+[Raw result](panel-layout-2026-10-24/readback.json):
+
+| Getter | `valve.steam.desktopgame.0` | `valve.steam.gamepadui.main` |
+|---|---|---|
+| FindOverlay | 0, Success | 0, Success |
+| Rendering process | `gamescope-wl` | `gamescope-wl` |
+| Width | 0; 2.6700000763 m | 0; 2.6670000553 m |
+| Curvature | 0; 0 | 0; 0 |
+| Transform type | 0; 5, DashboardTab | 0; 5, DashboardTab |
+| Absolute transform | 18, WrongTransformType | 18, WrongTransformType |
+| Tracked-device-relative transform | 18, WrongTransformType | 18, WrongTransformType |
+| Coordinate transform, center, standing origin | 0; identity matrix | 0; scaled/translated matrix |
+| Coordinate transform, center, seated origin | 23, RequestFailed | 23, RequestFailed |
+| Coordinate transform, center, raw origin | 23, RequestFailed | 23, RequestFailed |
+
+The dashboard and both panels were reported hidden; neither panel was active.
+The standing-space matrix is the transform for the overlay point `(0.5, 0.5)`;
+it does not identify World/Dashboard/Theater/controller docking or recreate a
+dashboard frame. The Steam panel's basis has scale about 0.369. Treat neither
+that scaled matrix nor the hidden Gamescope panel's identity as a validated
+physical placement to feed to an absolute-transform setter. Visible placement,
+matrix freshness and correspondence to dashboard size were not checked by a
+wearer.
+
+## API and dashboard boundary
+
+The ABI and result names were checked against Valve's
+[OpenVR v2.12.14 C header](https://github.com/ValveSoftware/openvr/blob/v2.12.14/headers/openvr_capi.h)
+and [C++ interface comments](https://github.com/ValveSoftware/openvr/blob/v2.12.14/headers/openvr.h).
+That header declares `IVROverlay_028`; its SHA-256 is
+`d58a2b149e434b2b8ee25cb4253ca6157feed8092f621e78ecfed6846d35d3e4`.
+The absolute getter is explicitly limited to absolute transforms. The
+coordinate getter returns the 3D transform for a 2D overlay point. Public
+`IVROverlay_028` has no getter/setter pair for dashboard dock location or frame
+scene-graph state. The probe fails closed if that exact interface is absent.
+
+Read-only inspection of the shipped dashboard
+`/opt/steamvr/resources/webinterface/dashboard/chunk~8012d0c89.js`
+(SHA-256 `937ec62c67a481f030a416099ceb98b0fe2a702aea5a0705601c6c40d4969f6d`)
+found:
+
+- `dockLocation` reads an internal `_getDockLocation(frameID)` store;
+  `SetDockLocation` updates that store or sends a VRLink request.
+- `m_mapLastRelativeTransformForDockLocation` keeps per-location transforms.
+  World initialization requests a dashboard scene-graph transform through
+  `requestSGTransform`, then updates the component's `xfTransform`.
+- The `vrcmd_dock_overlay` handler accepts `dashboard`, `lefthand`, `righthand`,
+  `theater` and `world`. It selects the frame associated with the supplied key,
+  **falls back to the active frame if no match exists**, sets dock location and
+  may switch frame. This is not an exact pose restore or a readback response.
+
+Those are observations of shipped internal code, not proof that Frame Control
+can safely access its state through a supported external API. No dashboard
+JavaScript was injected, private store edited or VRLink command sent. The
+active-frame fallback is an additional reason not to experiment with docking
+commands on a stale key.
+
+The [2026-09-28 probe](../panels.md#saved-spatial-layouts-blocked-on-the-current-panel-route)
+on SteamOS 0.4.1 / SteamVR 2.18.1 recorded an absolute setter returning
+12 (`PermissionDenied`) on a temporary, test-owned gamescope panel. That setter
+result is **historical**, not a new test on 2.18.2. The newer read-only results
+above neither overturn nor reverify it.
+
+## Commands, safety and cleanup
+
+Read-only inspection used `ssh frame` with `BatchMode=yes` and
+`ConnectTimeout=10`, `cat /etc/os-release`, battery sysfs reads,
+`systemctl --user is-active gamescope-session.service plasma-workspace.target`,
+process inspection, and `vrcmd --version`, `--help`, `--overlays`. An initial
+`--listoverlays` attempt returned `Unknown command`; `--overlays` is the actual
+enumeration command. Dashboard sources were read/copied to local `/tmp` for
+inspection. No files were installed on the Frame.
+
+Run the retained probe from the repository root, following
+[the shared-device rules](../testing.md#headset-smoke-test). Stop if the lock is
+occupied or battery is at/below 20%; never remove another task's lock:
+
+```sh
+ssh -o BatchMode=yes -o ConnectTimeout=10 frame \
+  'set -eu; mkdir /tmp/frame-test.lock || exit 3; trap "rmdir /tmp/frame-test.lock" EXIT; timeout 25 python3 -' \
+  < docs/evidence/panel-layout-2026-10-24/probe.py
+```
+
+This command acquired the lock, completed with exit 0 and released it. A
+subsequent check confirmed the lock absent, Game Mode active, and Steam,
+`vrserver` and `vrcompositor` running. The probe's only headset filesystem
+change was creating/removing that shared lock. Its Python source ran from
+stdin. There were no test panels, installs, profiles or services to remove.
+
+No mutation test was essential: without verified dock/relative-frame readback,
+there was no exact original layout and bounded rollback to justify changing a
+panel. Existing user panels were never focused, shown, hidden, resized, moved
+or docked. No global settings, security, passwords, runtime processes or modes
+were changed; no reboot or reset occurred.
+
+## Validation and remaining gaps
+
+Existing `tests/test_panels.py` covers main-panel enumeration, hidden panels,
+focus revalidation, unavailable-runtime errors and HTTP authentication/Host/
+Origin guards. `tests/test_page_scripts.py` checks the production page's shared
+JavaScript scope. These offline checks do not prove spatial placement. The
+retained probe is evidence tooling, not a new product API; no fake layout
+backend or layout tests claiming device support were added.
+
+Validation passed:
+
+```sh
+python3 -m unittest discover -s tests -p test_panels.py -v       # 8 passed
+python3 -m unittest discover -s tests -p test_page_scripts.py -v # 5 passed
+python3 -m py_compile docs/evidence/panel-layout-2026-10-24/probe.py
+python3 -m json.tool docs/evidence/panel-layout-2026-10-24/readback.json
+git diff --check
+```
+
+The initial panel-suite attempt hit sandbox socket restrictions in four HTTP
+tests; rerunning with loopback sockets permitted passed all eight. No real
+headset connection is used by those tests. The full suite and fake Frame were
+not run for this evidence-only change.
+
+Before shipping layouts, a native route still needs proof of dock state and
+relative-frame readback, authorized restore on an owned test panel with exact
+rollback, and correspondence between saved size/pose and visible placement.
+It also needs stable source identity and a fresh capture-permission/ticket
+flow when reopening viewers. Reconnect, panel recreation, reboot recovery,
+Steam-launched gameplay, controller docking and worn-headset input were not
+tested here. The existing Frame Control-owned media renderer is not proof that
+Steam/gamescope panels can be restored. No third-party overlay app was used.
+
+## Announcement
+
+We rechecked saved panel layouts on SteamOS 0.5.6. SteamVR exposes some panel
+geometry, but we have not verified safe restoration of Steam's panel positions
+and docking. Saved layouts remain unavailable; use SteamVR's dashboard to
+arrange panels. The panel switcher continues to list and show open panels.

docs/evidence/panel-layout-2026-10-24/probe.py

@@ -0,0 +1,89 @@
+"""Read-only issue #31 probe; pipe to `ssh frame 'timeout 25 python3 -'`.
+
+Acquire /tmp/frame-test.lock first per docs/testing.md. No overlay is created,
+focused, docked or changed. Background init (3) does not start SteamVR.
+ABI: ValveSoftware/openvr v2.12.14 headers/openvr_capi.h, IVROverlay_028.
+"""
+import ctypes as C
+import json
+from pathlib import Path
+
+H = C.c_uint64
+Matrix = C.c_float * 12
+
+
+class Vector2(C.Structure):
+    _fields_ = [('v', C.c_float * 2)]
+
+
+def probe():
+    vr = C.CDLL('/opt/steamvr/bin/linuxarm64/libopenvr_api.so')
+    vr.VR_InitInternal2.argtypes = [C.POINTER(C.c_int), C.c_int, C.c_char_p]
+    vr.VR_InitInternal2.restype = C.c_uint32
+    vr.VR_GetGenericInterface.argtypes = [C.c_char_p, C.POINTER(C.c_int)]
+    vr.VR_GetGenericInterface.restype = C.c_void_p
+    vr.VR_ShutdownInternal.argtypes = []
+    vr.VR_ShutdownInternal.restype = None
+    err = C.c_int()
+    vr.VR_InitInternal2(C.byref(err), 3, None)
+    report = {'init_error': err.value, 'interface': 'IVROverlay_028', 'panels': []}
+    if err.value:
+        return report
+    try:
+        ptr = vr.VR_GetGenericInterface(b'FnTable:IVROverlay_028', C.byref(err))
+        report['interface_error'] = err.value
+        if err.value or not ptr:
+            return report
+        table = C.cast(ptr, C.POINTER(C.c_void_p))
+
+        def function(slot, result, *args):
+            return C.CFUNCTYPE(result, *args)(table[slot])
+
+        def read(slot, handle, output_type):
+            output = output_type()
+            rc = function(slot, C.c_int, H, C.POINTER(output_type))(handle, C.byref(output))
+            return {'rc': rc, 'value': output.value if rc == 0 else None}
+
+        report['dashboard_visible'] = function(68, C.c_bool)()
+        for key in ('valve.steam.desktopgame.0', 'valve.steam.gamepadui.main'):
+            row = {'key': key}
+            report['panels'].append(row)
+            handle = H()
+            row['find_rc'] = function(0, C.c_int, C.c_char_p, C.POINTER(H))(
+                key.encode(), C.byref(handle))
+            if row['find_rc']:
+                continue
+            pid = function(10, C.c_uint32, H)(handle)
+            row['rendering_pid'] = pid
+            try:
+                row['rendering_comm'] = Path('/proc/%d/comm' % pid).read_text().strip()
+            except OSError:
+                row['rendering_comm'] = None
+            row['visible'] = function(45, C.c_bool, H)(handle)
+            row['active_dashboard'] = function(69, C.c_bool, H)(handle)
+            row['width_m'] = read(23, handle, C.c_float)
+            row['curvature'] = read(25, handle, C.c_float)
+            row['transform_type'] = read(32, handle, C.c_int)
+            for name, slot, scalar in (('absolute', 34, C.c_int),
+                                       ('tracked_device_relative', 36, C.c_uint32)):
+                origin = scalar()
+                matrix = Matrix()
+                rc = function(slot, C.c_int, H, C.POINTER(scalar), C.POINTER(Matrix))(
+                    handle, C.byref(origin), C.byref(matrix))
+                row[name] = {'rc': rc, 'origin_or_device': origin.value if rc == 0 else None,
+                             'matrix': list(matrix) if rc == 0 else None}
+            row['coordinate_transforms'] = []
+            for origin in (0, 1, 2):  # seated, standing, raw/uncalibrated
+                matrix = Matrix()
+                rc = function(46, C.c_int, H, C.c_int, Vector2, C.POINTER(Matrix))(
+                    handle, origin, Vector2((.5, .5)), C.byref(matrix))
+                row['coordinate_transforms'].append({
+                    'tracking_origin': origin, 'coordinates': [.5, .5], 'rc': rc,
+                    'matrix': list(matrix) if rc == 0 else None})
+        return report
+    finally:
+        vr.VR_ShutdownInternal()
+
+
+if __name__ == '__main__':
+    print(json.dumps(probe(), indent=2, allow_nan=False))

docs/evidence/panel-layout-2026-10-24/readback.json

@@ -0,0 +1,152 @@
+{
+  "init_error": 0,
+  "interface": "IVROverlay_028",
+  "panels": [
+    {
+      "key": "valve.steam.desktopgame.0",
+      "find_rc": 0,
+      "rendering_pid": 297037,
+      "rendering_comm": "gamescope-wl",
+      "visible": false,
+      "active_dashboard": false,
+      "width_m": {
+        "rc": 0,
+        "value": 2.6700000762939453
+      },
+      "curvature": {
+        "rc": 0,
+        "value": 0.0
+      },
+      "transform_type": {
+        "rc": 0,
+        "value": 5
+      },
+      "absolute": {
+        "rc": 18,
+        "origin_or_device": null,
+        "matrix": null
+      },
+      "tracked_device_relative": {
+        "rc": 18,
+        "origin_or_device": null,
+        "matrix": null
+      },
+      "coordinate_transforms": [
+        {
+          "tracking_origin": 0,
+          "coordinates": [
+            0.5,
+            0.5
+          ],
+          "rc": 23,
+          "matrix": null
+        },
+        {
+          "tracking_origin": 1,
+          "coordinates": [
+            0.5,
+            0.5
+          ],
+          "rc": 0,
+          "matrix": [
+            1.0,
+            0.0,
+            0.0,
+            0.0,
+            0.0,
+            1.0,
+            0.0,
+            0.0,
+            0.0,
+            0.0,
+            1.0,
+            0.0
+          ]
+        },
+        {
+          "tracking_origin": 2,
+          "coordinates": [
+            0.5,
+            0.5
+          ],
+          "rc": 23,
+          "matrix": null
+        }
+      ]
+    },
+    {
+      "key": "valve.steam.gamepadui.main",
+      "find_rc": 0,
+      "rendering_pid": 297037,
+      "rendering_comm": "gamescope-wl",
+      "visible": false,
+      "active_dashboard": false,
+      "width_m": {
+        "rc": 0,
+        "value": 2.6670000553131104
+      },
+      "curvature": {
+        "rc": 0,
+        "value": 0.0
+      },
+      "transform_type": {
+        "rc": 0,
+        "value": 5
+      },
+      "absolute": {
+        "rc": 18,
+        "origin_or_device": null,
+        "matrix": null
+      },
+      "tracked_device_relative": {
+        "rc": 18,
+        "origin_or_device": null,
+        "matrix": null
+      },
+      "coordinate_transforms": [
+        {
+          "tracking_origin": 0,
+          "coordinates": [
+            0.5,
+            0.5
+          ],
+          "rc": 23,
+          "matrix": null
+        },
+        {
+          "tracking_origin": 1,
+          "coordinates": [
+            0.5,
+            0.5
+          ],
+          "rc": 0,
+          "matrix": [
+            0.3689989447593689,
+            0.0,
+            0.0008894503116607666,
+            -0.5048462152481079,
+            0.0,
+            0.36899998784065247,
+            0.0,
+            1.2510287761688232,
+            -0.0008894503116607666,
+            0.0,
+            0.3689989447593689,
+            -1.1726053953170776
+          ]
+        },
+        {
+          "tracking_origin": 2,
+          "coordinates": [
+            0.5,
+            0.5
+          ],
+          "rc": 23,
+          "matrix": null
+        }
+      ]
+    }
+  ],
+  "interface_error": 0,
+  "dashboard_visible": false
+}

docs/panels.md

@@ -190,7 +190,24 @@ HTTP focus is not evidence of worn-headset laser input. Follow the
 
 ## Saved spatial layouts: blocked on the current panel route
 
-**Verified 2026-09-28**, same build, using a temporary xterm panel with
+**Rechecked 2026-10-24**, SteamOS 0.5.6, BUILD_ID `20261015.6141207`,
+SteamVR 2.18.2: a read-only probe of the existing Gamescope and Steam main
+panels still reports type 5 (`DashboardTab`), and both the absolute and
+tracked-device-relative getters return 18 (`WrongTransformType`). Width and
+curvature read successfully. **Some pose readback is available:**
+`GetTransformForOverlayCoordinates` at the panel center succeeds in standing
+space; seated and raw origins return 23 (`RequestFailed`). Both panels and the
+dashboard were hidden. That matrix snapshot does not identify docking, prove
+visible placement, or establish a restore operation. The shipped dashboard
+stores dock location and relative transforms internally; no supported external
+snapshot/restore pair was established. No setters or docking commands were run
+in this recheck. See the [exact probe, results, cleanup and remaining
+gaps](evidence/panel-layout-2026-10-24.md). Saved layouts remain unavailable.
+
+### Earlier mutation evidence (2026-09-28)
+
+**Verified 2026-09-28**, SteamOS 0.4.1, BUILD_ID `20260925.6191901`,
+SteamVR 2.18.1, using a temporary xterm panel with
 `STEAM_GAME=2000999031` and `FnTable:IVROverlay_028` from
 `/opt/steamvr/bin/linuxarm64/libopenvr_api.so`: