fix: default distributions to automatic GPU support with CPU fallback

docs/BUILDING.md

@@ -86,6 +86,14 @@ search starts a model process; the desktop retains a prewarmed query worker.
 
 ## Cross-compilation and native release matrix
 
+Normal distribution worker builds and staging default to `auto`: Metal on
+macOS, Vulkan on Windows/Linux, with CPU fallback in the same application.
+Users do not choose a CPU/GPU edition or rebuild for their graphics card.
+Windows/Linux build machines need the Vulkan SDK including `glslc`; absence
+fails release preparation instead of quietly generating a CPU-only runtime.
+The compilation SDK is not an end-user requirement. Explicit `--backend cpu`
+commands in the VM development sections are internal test configurations.
+
 The shared Rust engine/service has no GUI dependency. Install a destination
 Rust target with `rustup target add TARGET`, then build using
 `cargo build -p searchi-cli --target TARGET --locked`. This also requires the

docs/ROADMAP.md

@@ -49,6 +49,10 @@ Status: implementation started; no production release yet. Windows VM tests use
 - [ ] Isolated extraction workers with timeouts and resource ceilings.
 
 ## 5. Release gates
+- [x] Normal worker build/staging defaults to hardware-detecting auto with CPU
+  fallback; missing Vulkan/glslc fails configuration rather than hiding GPU loss.
+- [ ] Provision release-build GPU SDKs and verify one hardware-detecting package
+  per OS/architecture, including missing-driver fallback and dependency closure.
 - [x] Windows desktop archive packager includes explicit runtime/helper files
   and notices, checks architecture and records per-file checksums; excludes
   model caches and user data. Controlled packaging regression tests pass.

docs/SEMANTIC.md

@@ -33,6 +33,13 @@ an external OpenMP runtime. Production CMake supports cpu, auto, metal, vulkan,
 and cuda; CPU builds force GPU flags off. Runtime/provider parity and packaging
 on other operating systems remain independent release checks.
 
+The normal build/staging default is `auto`, shipping GPU support together with
+CPU fallback: Metal on macOS, Vulkan on Windows/Linux. Runtime detection chooses
+the usable device; users do not need hardware-specific builds. Release builders
+must have the relevant compilation SDK. Missing Vulkan/glslc now fails the
+normal build rather than silently omitting acceleration. Actual GPU parity,
+loader/dependency packaging and no-driver CPU fallback still require evidence.
+
 | Artifact | Bytes | SHA256 |
 | --- | ---: | --- |
 | embeddinggemma-2-Q8_0.gguf | 309,855,456 | 2188ac1deca4b77dffefd603c2776a9d76d9d74ec01841392982ebb840b09135 |
@@ -264,4 +271,4 @@ point-localization failures and unsuppressed no-answer results. Strong file
 recall is insufficient for accurate spoken-topic navigation. A ten-second audio
 experiment reduces some distances but does not close that gate; it is not a
 new default. Quality policies must be validated on held-out data rather than
-inventing thresholds from the evaluation corpus.
+inventing thresholds from the evaluation corpus.

docs/VALIDATION.md

@@ -11,8 +11,15 @@ The Windows archive packager has two controlled Python regressions: complete
 required file collection with checksum verification and user-settings exclusion,
 and mismatched worker architecture preserving the previous archive. Both pass.
 An actual CPU-only Tauri embedded-frontend Release build has been started;
-archive creation, native launch outside the source tree and clean-machine
-installation remain unverified until its completion and separate checks.
+the embedded-frontend Release application build completed in 7m 25s. CPU-only
+describes its VM test context, not a supported end-user edition. The normal
+worker build/staging defaults are now auto and require GPU compilation support
+alongside CPU fallback. The previously staged CPU worker remains an internal
+test artifact; archive creation, automatic-runtime dependency packaging, native
+launch outside the source tree and clean-machine installation remain unverified.
+Actual `auto` configuration correctly rejected this VM's missing Vulkan library,
+headers and `glslc`; no GPU-capable worker/package is claimed. Both staging
+regressions still pass using explicit internal CPU test configuration.
 
 Offline staging now verifies the native license and every bundled Google asset
 before modifying resources. Two Python regressions verify missing-model rejection