Delete the decisions and design logs; scripts, rigs and xtask off the root

Iris: "remove both decisions and iris.md. I've decided to instead make
decisions when planning with agents rather than after they do things, and
they're both too long for me to wanna read, + don't cover all the
decisions I'll wanna make about the code anyways. I'll just naturally run
into things for now. Todo is important though."

So docs/DECISIONS.md (850 lines) and docs/IRIS.md (1,986) are gone, and
AGENTS.md now says not to start another: raise a choice while planning it
with her, otherwise decide it and put the reasoning at the code it
governs. The TODO lists stay. docs/SUBAGENTS_DECISIONS.md went with them
-- same artefact, same reasoning, and she did not name it, so its six
decisions were folded into docs/SUBAGENTS.md rather than deleted.

Deleting the logs left ~30 citations dangling in code comments and docs.
Each states its reason inline and cited the file only for provenance, so
they now read "decided 2026-09-07" or name the module doc that carries
the reasoning.

The root had six things that were not a program or a document. Moved,
per "I only meant top level sh files":

  run-tests.sh, test-wg-tunnel.sh, wg-setup-host.sh  -> scripts/
  rigs/                                              -> scripts/rigs/
  xtask/                                             -> scripts/xtask/

A project's own scripts stayed with the project: app/*.sh, app-rust/*.sh,
iris/*.sh and server/enroll-link.sh did not move.

`target/` at the root is deleted and cannot come back: there was never a
workspace there, and the 29 MB was only xtask's scratch space, now in
scripts/xtask/target/. `cargo xtask apk` still runs from the repo root
and now publishes to scripts/build/outputs/apk/<mode>/ -- one directory
deep, because that is what Dev Updater's `*/build/outputs/apk/*/*.apk`
discovery pattern needs, and scripts/xtask/build would have been two.

Verified: ./scripts/run-tests.sh and `cd iris && cargo test` green, clippy
and fmt clean everywhere, `cargo xtask apk debug --abi x86_64` builds and
signs an APK carrying lib/x86_64/libai_app.so at the new publish path, and
the repo root is now eleven entries with no build output among them.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/rigs/gpu-probe/src/main.rs

@@ -0,0 +1,164 @@
+//! Ask a device whether it can give iris the GPU it asks for.
+//!
+//! Until 2026-09-04 iris's renderer bound every texture it had drawn as one
+//! binding array and indexed it non-uniformly from the shader, which needed
+//! descriptor indexing and a very large per-stage binding-array limit
+//! (101,000 elements: 100,000 textures and 1,000 samplers,
+//! `UiLimits::default`). That was ordinary on a desktop and, per
+//! TEXTURES.md's "iris's binding array does not survive real Android
+//! hardware", not available on a real share of Android GPUs -- and it failed
+//! outright on this emulator's software Vulkan, which is what this rig
+//! caught first. iris now asks for nothing beyond wgpu's own defaults (see
+//! `iris/src/default/render.rs`): the glyph atlas is one `texture_2d_array`
+//! and a standalone image is its own ordinary bind group, and neither needs
+//! descriptor indexing. This rig still asks `request_device` for exactly
+//! what iris asks for, so it keeps being the answer to "does iris's actual
+//! device request succeed here" rather than a guess from reading the code.
+//!
+//! It runs as a plain executable with no window and no APK, because
+//! `request_adapter` needs no surface -- so it can be pushed to a device with
+//! `adb push` and run from `/data/local/tmp`, which is far cheaper than an
+//! app. What it therefore cannot answer is anything about presenting to a
+//! surface; that is the Android backend's own problem.
+
+mod vk;
+
+use wgpu::*;
+
+/// What `iris/src/default/render.rs` asks `request_device` for, now that the
+/// binding array is gone: nothing beyond wgpu's own default feature set.
+fn iris_features() -> Features {
+    Features::empty()
+}
+
+/// The one non-default limit iris asks for -- unrelated to the binding array,
+/// kept for the big storage buffers behind rects/glyphs.
+const IRIS_MAX_BUFFER_SIZE: u64 = 1 << 30;
+
+/// Mirrors `iris_core::device_limits()` (`iris/core/src/render/mod.rs`) --
+/// cannot call it directly, since this rig is deliberately its own crate,
+/// not a workspace member (this file's own Cargo.toml comment). Keep the
+/// two in sync by hand when one changes; this rig's whole purpose is "does
+/// the device iris actually builds come back," so a stale copy here would
+/// silently stop answering that question. Zeroed rather than left at
+/// `Limits::default()`'s desktop-tier values because nothing in iris
+/// creates a `ComputePipeline` or a `@compute` shader stage -- found by
+/// grepping the whole `iris`/`iris-core` tree before this rig's comment was
+/// written -- and the unconditional default request is what crashed
+/// `request_device` on the Android emulator's software GL path
+/// (`EMU_GPU=software`, `force-gles`: SwiftShader's GL reports itself as
+/// OpenGL ES 3.0, which has no compute shaders at all, so the adapter's
+/// real limit is 0). The same would happen on a real GLES-3.0-only Android
+/// device.
+fn iris_limits() -> Limits {
+    Limits {
+        max_buffer_size: IRIS_MAX_BUFFER_SIZE,
+        max_compute_workgroup_storage_size: 0,
+        max_compute_invocations_per_workgroup: 0,
+        max_compute_workgroup_size_x: 0,
+        max_compute_workgroup_size_y: 0,
+        max_compute_workgroup_size_z: 0,
+        max_compute_workgroups_per_dimension: 0,
+        ..Default::default()
+    }
+}
+
+fn main() {
+    vk::report();
+
+    let instance = Instance::new(InstanceDescriptor {
+        backends: Backends::from_env().unwrap_or(Backends::PRIMARY),
+        ..InstanceDescriptor::new_without_display_handle()
+    });
+
+    let adapters = pollster::block_on(instance.enumerate_adapters(Backends::all()));
+    println!("adapters: {}", adapters.len());
+    for adapter in &adapters {
+        let info = adapter.get_info();
+        println!(
+            "  {:?} {} ({:?})",
+            info.backend, info.name, info.device_type
+        );
+        // Compute is a *downlevel* capability, not a feature: Vulkan
+        // grants it to any 1.0 device, and GLES only from ES 3.1. So
+        // "can iris use a compute pass here" is this flag on every
+        // adapter iris might fall back to, not just the preferred one.
+        let down = adapter.get_downlevel_capabilities();
+        let limits = adapter.limits();
+        println!(
+            "    compute shaders: {}  (shader model {:?})",
+            down.flags.contains(DownlevelFlags::COMPUTE_SHADERS),
+            down.shader_model
+        );
+        println!(
+            "    max compute invocations/workgroup: {}, workgroup storage: {} bytes",
+            limits.max_compute_invocations_per_workgroup, limits.max_compute_workgroup_storage_size
+        );
+    }
+
+    let Some(adapter) = pollster::block_on(instance.request_adapter(&RequestAdapterOptions {
+        power_preference: PowerPreference::default(),
+        compatible_surface: None,
+        force_fallback_adapter: false,
+        ..Default::default()
+    }))
+    .ok() else {
+        println!("\nNO ADAPTER");
+        std::process::exit(1);
+    };
+
+    let info = adapter.get_info();
+    println!(
+        "\nchosen: {:?} {} ({:?})",
+        info.backend, info.name, info.device_type
+    );
+    println!("driver: {} {}", info.driver, info.driver_info);
+
+    let have = adapter.features();
+    println!("\nfeatures iris requires:");
+    let mut missing = Features::empty();
+    for f in iris_features().iter() {
+        let ok = have.contains(f);
+        println!(
+            "  {:60} {}",
+            format!("{f:?}"),
+            if ok { "yes" } else { "NO" }
+        );
+        if !ok {
+            missing |= f;
+        }
+    }
+
+    let limits = adapter.limits();
+    println!("\nlimits iris requires:");
+    println!(
+        "  {:52} want {:>7}  have {:>7}  {}",
+        "max_buffer_size",
+        IRIS_MAX_BUFFER_SIZE,
+        limits.max_buffer_size,
+        if limits.max_buffer_size >= IRIS_MAX_BUFFER_SIZE {
+            "ok"
+        } else {
+            "TOO SMALL"
+        }
+    );
+
+    // The question that actually matters: does the device iris builds come
+    // back, or does wgpu refuse it? With no features and no binding-array
+    // limits requested, this is expected to succeed everywhere -- this rig
+    // is what turned that from an assumption into a measurement, first on
+    // this emulator's software Vulkan.
+    let wanted = iris_limits();
+    match pollster::block_on(adapter.request_device(&DeviceDescriptor {
+        required_features: iris_features(),
+        required_limits: wanted,
+        ..Default::default()
+    })) {
+        Ok(_) => println!("\nIRIS DEVICE: ok"),
+        Err(e) => println!("\nIRIS DEVICE: FAILED -- {e}"),
+    }
+
+    if !missing.is_empty() {
+        println!("\nmissing features: {missing:?}");
+    }
+}