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Wlroots Integration Status ​

Date: February 6, 2026

Status: Paused. The wlroots compositor integration and Fennel bindings were removed after repeated failures in headless/Xvfb environments. The work is not currently active in the codebase.

What Was Attempted ​

  • Headless wlroots compositor embedded inside the Space process.
  • Xwayland-based app launch (xterm) rendered into a wlroots scene output, surfaced as a texture in Space.
  • Snapshot test to capture the xterm surface via the wlroots output texture.

Problems Encountered ​

  • DMA-BUF import consistently failed in headless/Xvfb runs with EGL_BAD_MATCH during eglCreateImageKHR, forcing a fallback path.
  • Readback paths were unreliable: wlroots output textures remained nil or effectively black.
  • wlr_output commit path was fragile in headless runs; earlier iterations hit output->back_buffer == NULL assertions.
  • Xwayland socket binding collided with existing X0..X2 sockets in the test environment, leading to unstable startup.
  • Xwayland sometimes terminated mid-run, producing Broken pipe warnings and double-free crashes after test teardown.

Why We Stopped ​

The integration blocked e2e snapshot testing and destabilized the app during CI-like headless runs. The amount of low-level plumbing required (context ownership, output buffering, renderer readback and Xwayland lifecycle) exceeded the remaining time budget for this phase.

Next Steps (If We Revisit) ​

  • Run against a real GPU session (non-Xvfb) to validate DMA-BUF import and renderer paths.
  • Decide on a single authoritative render/commit model (wlroots output commit vs manual renderer begin/end) and document it.
  • Implement a robust pixel readback strategy for headless environments.
  • Isolate Xwayland lifecycle management from tests to avoid socket collisions and teardown crashes.