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IPC clients cannot capture their frame: MCP capture_frame 'not wired', per-exe atlas trigger and service screenshot trigger not serviced #1810
Description
On the IPC / service path there is no way to capture a client's frame from that client's side. Every per-app capture route fails, so a standalone forced-IPC (or shell) client's composited output can't be measured from the app.
Repro (win box, dev runtime built from fix/1795-local2d-flatten-honest, 2026-10-03)
Start the service, then run cube_zones_d3d11_win with XRT_FORCE_MODE=ipc DISPLAYXR_ZONES=1 DISPLAYXR_MCP=1.
| route | result |
|---|---|
per-app MCP capture_frame on \.\pipe\displayxr-mcp-<pid> |
{"error":"capture_frame not wired: compositor has not registered a handler. Rebuild with the MCP capture hooks enabled for this graphics API."}. The IPC client compositor (client_d3d11) never calls oxr_mcp_tools_set_capture_handler(). |
per-exe file trigger %TEMP%\displayxr_atlas_trigger.<exe> |
never consumed: the trigger file stays on disk and no PNG is written |
service %TEMP%\workspace_screenshot_trigger |
never consumed for a standalone client whose DP runs transparency = client-present. No capture WARN at all, so the pipeline never reached a capture site. |
The in-process compositors serve all of these, and CLAUDE.md says xrCaptureAtlasDXR routes through an "IPC branch". In practice none of the per-app paths reach the service's per-client atlas.
Why it matters
Colour work on the service path (#1795, ADR-044 §7: pure-zones / Local2D commits) can't be verified numerically from the client. The service stamps Local2D into the per-client atlas, so an atlas capture would be the oracle.
Expected
For an IPC client, capture_frame (and the per-exe trigger) should request the service's per-client atlas over IPC: pre-weave, ADR-044 §5 semantics, raw alpha under DXR_ATLAS_CAPTURE_RAW_ALPHA. Alternatively, the service-side screenshot trigger should also fire on the client-present / standalone path.
Shell-mode capture via the shell's MCP capture_frame (xrCaptureWorkspaceFrameDXR) is a separate route and is not covered by this report.
Activity
dfattal commentedon Oct 3, 2026
Also failing: the shell's MCP
capture_frame(\.\pipe\displayxr-mcp-shell, wrapsxrCaptureWorkspaceFrameDXR). It returned{"ok":false,"path_prefix":"...\Temp\displayxr_capture"}for a workspace with onecube_zones_d3d11_winclient. Setup: installed shell v2.3.2 on a dev service built from #1809's branch, 2026-10-03. David asked for this to be fixed so agents can verify the service path autonomously.fix(capture): IPC clients can capture their own atlas (#1810) (#1811)