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Jake 54d9adf1f0 fix(rb-07): runtime capabilities derive accelerators honestly

get_runtime_capabilities was returning `accelerators = ["cpu",
"vulkan"]` and `whisper.supports_gpu = true` regardless of build
config or runtime state. On a macOS build it falsely advertised
"vulkan" (the backend actually resolves via MoltenVK as Metal); on a
whisper-disabled build it claimed GPU support for an engine that
hadn't been linked.

Added `compose_accelerators(whisper_enabled, loader_available, target)`
— a pure helper that always emits "cpu" first and appends the
platform-appropriate GPU name only when whisper is compiled in AND the
Vulkan loader resolves. `supported_accelerators()` wraps it with the
live `cfg!(feature = "whisper")`, loader probe, and target OS.

`get_runtime_capabilities` now calls `supported_accelerators()` and
sets `whisper.supports_gpu = cfg!(feature = "whisper")`. Parakeet
stays CPU-only.

Five tests in `commands::models::tests` cover the permutation matrix:
whisper on/off, loader present/missing, macOS vs other. Both feature
configurations (`--features whisper` and `--no-default-features`)
build and pass tests.

Macos Metal-loader resolution on real hardware stays on the
ship-gate checklist — the detection logic is verifiable from Linux
but runtime behaviour is not.

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

2026-04-22 10:32:04 +01:00

2.8 KiB

Raw Blame History

RB-07 MAJOR: get_runtime_capabilities advertises wrong accelerators

Severity: MAJOR Path: src-tauri/src/commands/models.rs:435-489 Source: 2026-04-22 code review Labels: release-blocker, major, ui-integrity Status: RESOLVED (2026-04-22)

Resolution

Added a pure compose_accelerators(whisper_enabled, loader_available, target) -> Vec<String> helper. It always emits "cpu" first and appends "metal" (macOS) or "vulkan" (Linux/Windows) only when whisper is compiled in and vulkan_loader_available() resolves the platform's loader shim.

supported_accelerators() reads cfg!(feature = "whisper"), runs the live loader probe, and delegates to the helper. get_runtime_capabilities calls supported_accelerators() in place of the hard-coded vec!["cpu", "vulkan"]. Whisper's supports_gpu is now cfg!(feature = "whisper") — false on whisper-disabled builds.

Five regression tests in commands::models::tests cover:

cpu_only_when_whisper_disabled (both targets)
cpu_only_when_loader_missing (both targets)
macos_with_loader_advertises_metal
non_macos_with_loader_advertises_vulkan
cpu_is_always_first_entry (contract the frontend relies on)

Both cargo test -p kon --lib and cargo test -p kon --lib --no-default-features pass the new suite; both cargo build -p kon and cargo build -p kon --no-default-features compile clean.

Runtime GUI verification on a real macOS box is still on the ship-gate checklist — the detection logic is correct in code; Metal-loader resolution on hardware is not something we can unit-test from a Linux CI.

Problem

The IPC response hard-codes accelerators = ["cpu", "vulkan"] and supports_gpu = true for Whisper, even when:

detect_active_compute_device would report metal on macOS (via MoltenVK).
The binary was compiled without the whisper feature — in which case Whisper supports_gpu is meaningless because there is no Whisper backend at all.

The frontend uses this response to render Settings toggles (GPU selection, active-device badge, feature availability). Wrong values mean wrong UI states on exactly the builds this function is meant to describe.

Acceptance

accelerators is derived from actual build configuration and runtime probe, not hard-coded.
On macOS, accelerators includes "metal" when the Metal loader resolves.
On whisper-disabled builds, Whisper entries advertise supports_gpu = false (or the engine is omitted from the response entirely).
Regression tests cover each platform variant via cfg-gated test cases.

Fix scope

Medium. The detection helpers already exist (detect_active_compute_device, vulkan_loader_available); this is about wiring their output into the RuntimeCapabilities struct honestly.

Dependencies

None — standalone fix.

2.8 KiB Raw Blame History