Tap-to-apply chooser harness passes under QEMU (task 10.6b)

Host, 2026-09-28, branch close/themes (base 38c264e4). QEMU user-mode proof with a synthetic theme backend and synthetic Wayland touch only. No board, panel or real finger was involved. This result is not physical touch or timing evidence.

Command

nix build .#handheld-shell-rust --no-link --print-out-paths --max-jobs 1 --cores 6
# -> /nix/store/r5017cgy0vp7m1b86ibagy7ij5q2anv0-k230-shell-rust-riscv64-unknown-linux-gnu-0.1.0
nix build .#card-shell --no-link --print-out-paths
# -> /nix/store/j57c5im42d3rq5gxdar2ikmh22717zvc-k230-card-shell
python3 tests/rust_theme_chooser_qemu.py \
  --sway /nix/store/0a2f857nc1rz65gnjdfn46h32zsyxm18-sway-unwrapped-riscv64-unknown-linux-gnu-1.12/bin/sway \
  --rust /nix/store/r5017cgy0vp7m1b86ibagy7ij5q2anv0-k230-shell-rust-riscv64-unknown-linux-gnu-0.1.0/bin/k230-shell-rust \
  --output /tmp/q106

Result: PASS paired Sway/Rust theme carousel QEMU touch, synthetic backend; no physical touch.

The --sway argument must be the unwrapped binary that .#card-shell’s swaymsg symlink resolves to. Passing card-shell/bin/sway, which links to the wrapped sway-1.12, fails under qemu-riscv64-static with Exec format error, and the harness then times out waiting for the compositor. That was this session’s first attempt. The output directory must also be short because it holds the Wayland socket path.

Synthetic command log (theme-commands.jsonl, 11 requests)

["list"]
["preview", "000000000000000000000000"]
["preview", "000000000000000000000001"]
["preview", "000000000000000000000002"]
["preview", "000000000000000000000002"]
["activate", "000000000000000000000002", "--expected-generation", "bbbbbbbbbbbbbbbbbbbbbbbb"]
["preview", "000000000000000000000002", "--background", "dddddddddddddddddddddddd"]
["activate", "000000000000000000000002", "--expected-generation", "eeeeeeeeeeeeeeeeeeeeeeee", "--background", "dddddddddddddddddddddddd"]
["preview", "000000000000000000000003"]
["preview", "000000000000000000000004"]
["activate", "000000000000000000000004", "--expected-generation", "bbbbbbbbbbbbbbbbbbbbbbbb"]

This shows the following:

• One-tap theme apply: a single centred tap activates the theme with its prepared generation. No separate Preview/Apply step exists.
• Background tap: the tap first prepares the exact background choice. It then activates that selection’s own distinct generation (eeee…), not the previous background’s generation. This is task 16’s correction.
• Rapid-tap coalescing: theme …03 was requested and then superseded. It was never activated, and only the later tap (…04) was activated.

Captures (not committed)

The run produced eight native headless PNGs plus a fixture preview. They are kept out of the repo to avoid adding binaries for synthetic output; their SHA-256 hashes are below.

c71d60314cfc83fb88a1d9886e9cb669b42f2cb033cfac81c33b0ad1a99d9a60  theme-list.png
884a425c35976b2395835ec0e8c53a8d50298df452ae0536fa2f9178eaa8f4f4  theme-list-dragged.png
dfd1856a95b64f8729356f7c818cf84efb6a4910b00f3ba85602d293744f4c24  theme-list-recentered.png
2db1f4e64a21fac5b5706f68f34b3d7be961d050ce915eafe9b9d5cd490da019  theme-tap-apply.png
e39f20d5922c476811ab87ee0ffef2ed75561aa2b8d4db3a6bba41cebe254811  theme-background-dragged.png
ddb715a02a191d06aa7bd073b8890e66089ec089ba1086f8c61f2db779619d36  theme-background-selected.png
a6258fa82fc85ab4c2cccbbd3c205af00502d00eae1e3706b212f92c51a8db85  theme-rapid-tap-coalesced.png
8f2dd65ccbd2e27e628fe2188de86be29213469a3dd51321367c8fa8403b95fe  settings.png

Limits

This proves the harness’s own synthetic flow on the current source. It does not establish panel layout fit, on-glass latency or real-finger behaviour. Those remain task 10.7 and task 14.4.