Phase 0: A1 Wayland baseline + state snapshot — major reframing

3 in-session reps of chromium-fourier 149 / brave_drops_test.html /
Plasma Wayland 6.6.4 (kwin-fourier 6.6.4-3 + qt6-base-fourier
6.11.0-3 carry-overs intact). Tight cluster IQR=0:
drops_total=0, drops_post_warmup=0, frames_total=1685, kwin %CPU
median=0.00, mean=0.04. Perf samples on kwin (~30 over 70s) show
zero composite/dmabuf/GL symbols — only event-loop bookkeeping.

Most likely mechanism: KWin direct-scanout fast-path engaged for
the single-visible-client video case. The campaign's load-bearing
hypothesis ("X11 + non-compositing WM avoids per-frame GL composite
of NV12") is structurally weakened — KWin already avoids that work
under Wayland for this workload. Phase 1 needs to add a
multi-window A1' variant and drm_info-during-playback to confirm
direct-scanout, then revisit matrix cell design.

revert.log entry 6: SDDM autologin + state.conf swap that landed
the Plasma Wayland session for the A1 reps. Backup of original
state.conf preserved at /var/lib/sddm/state.conf.x11-research-bak;
single-command revert documented.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

worklist.md

@@ -37,11 +37,14 @@ inventory and baseline-anchor work below.
 - [x] **Experimental matrix drafted.** 3 browsers × 2 decode
   paths × 2 sessions = 12 cells (some N/A where libva isn't
   supported). See `phase0_findings.md` § "Experimental matrix".
-- [ ] State snapshot of ohm under current Plasma Wayland —
-  the campaign-start *before* photo. Unattended-tractable
-  via SSH. Captures package versions, kernel, kwin_wayland
-  PID + cmdline, governor, services, browser binary versions,
-  test asset paths, thermal_zone temps.
+- [x] State snapshot of ohm under current Plasma Wayland.
+  Captured 2026-05-03 in
+  `phase0_evidence/wayland_baseline_2026-05-03/01_live_session.txt`
+  + `02_predecessor_assets.txt`. Confirmed kwin_wayland 6.6.4 +
+  qt6-base-fourier 6.11.0-3 + kwin-fourier 6.6.4-3 carry-overs
+  intact, governor=performance, all three browsers + mpv
+  installed, predecessor's `run_browser_nodebug.sh` +
+  parsers + `brave_drops_test.html` test page reusable.
 - [x] Inventory of available X11 paths on ohm. Captured
   2026-05-03 in `phase0_evidence/x11_inventory_2026-05-03/`
   (raw `02_x11_paths.txt` + summary `inventory.md` § "Deliverable 2").
@@ -96,17 +99,26 @@ inventory and baseline-anchor work below.
   `/usr/bin/xtrace` from glibc is a syscall tracer, unrelated);
   optional, matrix doesn't strictly need protocol traces.
   perf_event_paranoid=2 — set to 1 once for unattended runs.
-- [ ] **A1 baseline: in-session Wayland-with-KWin anchor.**
-  Mandatory per the governing rule. 3 reps minimum (variance
-  is a real concern on this hardware per the predecessor
-  data) of a `kwin_timing_nodebug`-equivalent run on the
-  current Plasma Wayland session, captured into
-  `phase0_evidence/wayland_baseline_repN/`. **This is the
-  only Wayland baseline this campaign uses.** No
-  predecessor number substitutes for these reps even if the
-  predecessor measured an "identical" condition. The 3 reps
-  also surface the session-internal variance up front, so
-  Phase 1 thresholds aren't drawn against a single sample.
+- [x] **A1 baseline: in-session Wayland-with-KWin anchor.**
+  Captured 2026-05-03 14:23–14:31 CEST in
+  `phase0_evidence/wayland_baseline_2026-05-03/a1_rep[1-3]/`
+  + verdict in `a1_summary.md`. 3 reps,
+  `chromium-fourier-kwin` workload via
+  `run_browser_nodebug.sh`. **Tight cluster (IQR 0):**
+  drops_total=0, drops_post_warmup=0, frames_total=1685
+  (median), kwin %CPU median=0.00, mean=0.04. **Major
+  reframing finding:** kwin_wayland is doing essentially
+  zero per-frame work — perf reports show no GL / dmabuf /
+  composite symbols at all, only event-loop bookkeeping.
+  Most likely mechanism: KWin direct-scanout
+  (single-visible-client bypass). The campaign's
+  load-bearing hypothesis ("X11 will be measurably faster
+  because no KWin GL composite") is structurally weakened
+  — there's no per-frame KWin overhead for the X11 cells
+  to be faster than. Phase 1 needs to add a multi-window
+  A1' variant + drm_info-during-playback to confirm
+  direct-scanout, plus revisit cell-design per
+  `a1_summary.md` § "Phase 1 implications".
 
 ## Phase 1 — binding cells + measurement protocol