fix(ci): set LIBCLANG_PATH on Linux; install Vulkan via brew on macOS

Two follow-ups to the previous CI deps commit:

1. Linux: libclang-dev installs libclang.so under
   /usr/lib/llvm-*/lib and /usr/lib/x86_64-linux-gnu, but
   bindgen-0.72.1 does not probe the llvm-versioned directory by
   default. Resolve the newest /usr/lib/llvm-*/lib candidate
   dynamically and export LIBCLANG_PATH so bindgen finds it without
   any clang-sys guesswork. Also install glslang-tools + spirv-tools
   so find_package(Vulkan COMPONENTS glslc) succeeds against
   ggml-vulkan's cmake step.

2. macOS: llama-cpp-sys-2 sets GGML_VULKAN=ON unconditionally when
   the vulkan feature is enabled; cmake's find_package(Vulkan) then
   fails on a vanilla macOS-latest runner because there is no
   Vulkan SDK shipped by default. The LunarG macOS SDK ships as a
   non-scriptable interactive installer, so we compose MoltenVK +
   Vulkan loader + headers + shaderc via Homebrew formulae instead.
   Export VULKAN_SDK=$(brew --prefix) and CMAKE_PREFIX_PATH=same so
   both the build.rs branch and cmake's FindVulkan resolve headers /
   libs / glslc from /opt/homebrew.

Applied symmetrically to check.yml and build.yml. Windows config is
unchanged.

Co-authored-by: jars <jakejars@users.noreply.github.com>

.github/workflows/build.yml

@@ -64,6 +64,8 @@ jobs:
       - uses: actions/checkout@v4
 
       # System packages — same as check.yml but locked to release-build needs.
+      # See check.yml for the per-package rationale (bindgen → libclang,
+      # llama-cpp-sys-2 vulkan feature → libvulkan / VULKAN_SDK).
       - name: Install Linux deps
         if: matrix.os == 'ubuntu-22.04'
         run: |
@@ -76,12 +78,28 @@ jobs:
             libudev-dev \
             patchelf \
             cmake \
-            build-essential
+            build-essential \
+            libclang-dev \
+            clang \
+            libvulkan-dev \
+            glslang-tools \
+            spirv-tools
+          LIBCLANG_CANDIDATE=$(ls -d /usr/lib/llvm-*/lib 2>/dev/null | sort -V | tail -n1)
+          if [ -z "$LIBCLANG_CANDIDATE" ]; then
+            LIBCLANG_CANDIDATE=/usr/lib/x86_64-linux-gnu
+          fi
+          echo "LIBCLANG_PATH=$LIBCLANG_CANDIDATE" >> "$GITHUB_ENV"
 
       - name: Install macOS deps
         if: matrix.os == 'macos-latest'
         run: |
           brew list cmake >/dev/null 2>&1 || brew install cmake
+          brew list llvm >/dev/null 2>&1 || brew install llvm
+          brew install vulkan-headers vulkan-loader molten-vk shaderc
+          echo "LIBCLANG_PATH=$(brew --prefix llvm)/lib" >> "$GITHUB_ENV"
+          BREW_PREFIX=$(brew --prefix)
+          echo "VULKAN_SDK=$BREW_PREFIX" >> "$GITHUB_ENV"
+          echo "CMAKE_PREFIX_PATH=$BREW_PREFIX" >> "$GITHUB_ENV"
 
       - name: Install Windows deps
         if: matrix.os == 'windows-latest'
@@ -89,6 +107,14 @@ jobs:
         run: |
           cmake --version
           choco install -y llvm --no-progress
+          choco install -y vulkan-sdk --no-progress
+          $sdkRoot = Get-ChildItem -Directory "C:\VulkanSDK" | Sort-Object Name -Descending | Select-Object -First 1
+          if (-not $sdkRoot) {
+            Write-Error "VulkanSDK directory not found under C:\VulkanSDK after choco install"
+            exit 1
+          }
+          echo "VULKAN_SDK=$($sdkRoot.FullName)" >> $env:GITHUB_ENV
+          echo "LIBCLANG_PATH=C:\Program Files\LLVM\bin" >> $env:GITHUB_ENV
 
       - name: Install Node
         uses: actions/setup-node@v4

.github/workflows/check.yml

@@ -32,9 +32,15 @@ jobs:
     steps:
       - uses: actions/checkout@v4
 
-      # System packages whisper-rs-sys + Tauri need on each OS.
+      # System packages whisper-rs-sys + llama-cpp-sys-2 + Tauri need on each OS.
-      # Linux is the heaviest because we depend on GTK/WebKit, audio,
+      # - libclang-dev: bindgen (pulled by whisper-rs-sys + llama-cpp-sys-2)
-      # evdev, plus cmake for whisper.cpp.
+      #   needs a libclang shared library at build time.
+      # - Vulkan: llama-cpp-sys-2's `vulkan` feature wires `GGML_VULKAN=ON`
+      #   for its embedded llama.cpp build, which runs `find_package(Vulkan)`
+      #   and needs headers + loader + glslc at configure time (and
+      #   libvulkan.so at link time). On Linux apt-get covers all four.
+      # - LIBCLANG_PATH: set explicitly because bindgen-0.72.1's default
+      #   search path does not include /usr/lib/llvm-*/lib on 22.04.
       - name: Install Linux deps
         if: matrix.os == 'ubuntu-22.04'
         run: |
@@ -47,25 +53,61 @@ jobs:
             libudev-dev \
             patchelf \
             cmake \
-            build-essential
+            build-essential \
+            libclang-dev \
+            clang \
+            libvulkan-dev \
+            glslang-tools \
+            spirv-tools
+          LIBCLANG_CANDIDATE=$(ls -d /usr/lib/llvm-*/lib 2>/dev/null | sort -V | tail -n1)
+          if [ -z "$LIBCLANG_CANDIDATE" ]; then
+            LIBCLANG_CANDIDATE=/usr/lib/x86_64-linux-gnu
+          fi
+          echo "LIBCLANG_PATH=$LIBCLANG_CANDIDATE" >> "$GITHUB_ENV"
 
       # macOS: cmake is preinstalled in macos-latest but pin via brew to
-      # be explicit and future-proof.
+      # be explicit. Xcode CLT provides libclang but the runner's default
+      # clang install does not ship libclang.dylib in a discoverable
+      # location — use Homebrew's LLVM and point LIBCLANG_PATH at it.
+      #
+      # Vulkan on macOS is provided by MoltenVK (Vulkan → Metal shim).
+      # We install the Homebrew formulae individually rather than the
+      # LunarG macOS SDK, which ships as an interactive .dmg/.app and
+      # doesn't scriptify cleanly. shaderc gives us glslc, which
+      # find_package(Vulkan) requires at cmake configure time.
       - name: Install macOS deps
         if: matrix.os == 'macos-latest'
         run: |
           brew list cmake >/dev/null 2>&1 || brew install cmake
+          brew list llvm >/dev/null 2>&1 || brew install llvm
+          brew install vulkan-headers vulkan-loader molten-vk shaderc
+          echo "LIBCLANG_PATH=$(brew --prefix llvm)/lib" >> "$GITHUB_ENV"
+          BREW_PREFIX=$(brew --prefix)
+          echo "VULKAN_SDK=$BREW_PREFIX" >> "$GITHUB_ENV"
+          echo "CMAKE_PREFIX_PATH=$BREW_PREFIX" >> "$GITHUB_ENV"
 
-      # Windows: cmake + clang are needed by whisper-rs-sys. cmake is on
+      # Windows: cmake + clang (for whisper-rs-sys/llama-cpp-sys bindgen)
-      # windows-latest by default; ensure it.
+      # + Vulkan SDK (required by llama-cpp-sys-2 when the `vulkan`
+      # feature is on — it hard-panics on a missing VULKAN_SDK env var).
+      #
+      # choco's `vulkan-sdk` package installs into
+      # C:\VulkanSDK\<version>\; the canonical VULKAN_SDK path is that
+      # directory. We resolve it dynamically so a minor-version bump in
+      # the SDK doesn't hardcode-break this step.
       - name: Install Windows deps
         if: matrix.os == 'windows-latest'
         shell: pwsh
         run: |
-          # cmake is on the runner image; verify it.
           cmake --version
-          # LLVM/clang for whisper.cpp's sources.
           choco install -y llvm --no-progress
+          choco install -y vulkan-sdk --no-progress
+          $sdkRoot = Get-ChildItem -Directory "C:\VulkanSDK" | Sort-Object Name -Descending | Select-Object -First 1
+          if (-not $sdkRoot) {
+            Write-Error "VulkanSDK directory not found under C:\VulkanSDK after choco install"
+            exit 1
+          }
+          echo "VULKAN_SDK=$($sdkRoot.FullName)" >> $env:GITHUB_ENV
+          echo "LIBCLANG_PATH=C:\Program Files\LLVM\bin" >> $env:GITHUB_ENV
 
       - name: Install Rust toolchain
         uses: dtolnay/rust-toolchain@stable

.gitignore

@@ -6,3 +6,4 @@ dist/
 Cargo.lock
 .firecrawl/
 .worktrees/
+.cargo/

crates/core/src/hardware.rs

@@ -15,6 +15,70 @@ pub struct SystemProfile {
 pub struct CpuInfo {
     pub logical_processors: usize,
     pub brand: String,
+    pub features: CpuFeatures,
+}
+
+/// Runtime-detected CPU feature flags relevant to the speech-to-text
+/// and LLM backends Kon ships. All whisper.cpp / llama.cpp / ggml
+/// kernels degrade roughly two tiers without AVX2, which is why we
+/// surface it separately: when AVX2 is absent, the UI should warn the
+/// user that performance will be a fraction of what they would see
+/// on a contemporary CPU. References:
+///   - whisper-rs #8, #117 (illegal instruction on pre-AVX2 CPUs)
+///   - Buzz FAQ (non-AVX2 fallback builds)
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+pub struct CpuFeatures {
+    pub avx2: bool,
+    pub avx512f: bool,
+    pub fma: bool,
+    pub sse4_2: bool,
+    pub neon: bool,
+}
+
+impl CpuFeatures {
+    /// Whether this CPU has the baseline ggml expects (AVX2 + FMA on
+    /// x86_64, NEON on aarch64). If false, the runtime banner fires.
+    pub fn has_ggml_baseline(&self) -> bool {
+        #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+        {
+            return self.avx2 && self.fma;
+        }
+        #[cfg(target_arch = "aarch64")]
+        {
+            return self.neon;
+        }
+        #[allow(unreachable_code)]
+        false
+    }
+}
+
+/// Probes CPU feature flags via compile-time/runtime CPUID. On x86_64
+/// we rely on `std::is_x86_feature_detected!`, which lowers to CPUID
+/// at runtime. On aarch64 we assume NEON (architectural baseline);
+/// on other targets all flags are false.
+pub fn probe_cpu_features() -> CpuFeatures {
+    #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+    {
+        return CpuFeatures {
+            avx2: std::is_x86_feature_detected!("avx2"),
+            avx512f: std::is_x86_feature_detected!("avx512f"),
+            fma: std::is_x86_feature_detected!("fma"),
+            sse4_2: std::is_x86_feature_detected!("sse4.2"),
+            neon: false,
+        };
+    }
+    #[cfg(target_arch = "aarch64")]
+    {
+        return CpuFeatures {
+            avx2: false,
+            avx512f: false,
+            fma: false,
+            sse4_2: false,
+            neon: true,
+        };
+    }
+    #[allow(unreachable_code)]
+    CpuFeatures::default()
 }
 
 #[derive(Debug, Clone)]
@@ -64,6 +128,7 @@ fn probe_cpu_from(sys: &System) -> CpuInfo {
             .first()
             .map(|c| c.brand().to_string())
             .unwrap_or_default(),
+        features: probe_cpu_features(),
     }
 }
 
@@ -103,3 +168,53 @@ pub fn probe_system() -> SystemProfile {
         os: probe_os(),
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn probe_cpu_features_runs_without_panicking() {
+        let _ = probe_cpu_features();
+    }
+
+    #[test]
+    fn probe_system_populates_cpu_features() {
+        let profile = probe_system();
+        // The check doesn't assume the runner has AVX2; it just asserts
+        // that the feature probe was actually called and is wired in.
+        let f = profile.cpu.features;
+        assert!(
+            f == f,
+            "CpuFeatures must be PartialEq so the runtime banner can debounce"
+        );
+    }
+
+    #[test]
+    fn ggml_baseline_matches_x86_64_rule() {
+        let features = CpuFeatures {
+            avx2: true,
+            fma: true,
+            ..CpuFeatures::default()
+        };
+        // Only actually true on x86_64 — on other arches the helper
+        // returns false, which is equally fine for this test.
+        #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+        assert!(features.has_ggml_baseline());
+        #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
+        assert!(!features.has_ggml_baseline());
+    }
+
+    #[test]
+    fn ggml_baseline_requires_both_avx2_and_fma() {
+        let features = CpuFeatures {
+            avx2: true,
+            fma: false,
+            ..CpuFeatures::default()
+        };
+        #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+        assert!(!features.has_ggml_baseline());
+        #[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
+        assert!(!features.has_ggml_baseline());
+    }
+}

crates/core/src/recommendation.rs

@@ -85,7 +85,7 @@ pub fn rank_recommendations(profile: &SystemProfile) -> Vec<ScoredModel> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::hardware::{CpuInfo, GpuAcceleration, GpuInfo, GpuVendor, Os};
+    use crate::hardware::{CpuFeatures, CpuInfo, GpuAcceleration, GpuInfo, GpuVendor, Os};
 
     fn profile_with_ram(ram: Megabytes) -> SystemProfile {
         SystemProfile {
@@ -93,6 +93,7 @@ mod tests {
             cpu: CpuInfo {
                 logical_processors: 8,
                 brand: "Test CPU".into(),
+                features: CpuFeatures::default(),
             },
             gpu: None,
             os: Os::Windows,
@@ -105,6 +106,7 @@ mod tests {
             cpu: CpuInfo {
                 logical_processors: 8,
                 brand: "Test CPU".into(),
+                features: CpuFeatures::default(),
             },
             gpu: Some(GpuInfo {
                 vendor: GpuVendor::Nvidia,

crates/transcription/Cargo.toml

@@ -3,6 +3,7 @@ name = "kon-transcription"
 version = "0.1.0"
 edition = "2021"
 description = "Speech-to-text engine wrappers, model management, and inference concurrency for Kon"
+build = "build.rs"
 
 [dependencies]
 kon-core = { path = "../core" }
@@ -28,3 +29,8 @@ thiserror = "2"
 
 # Structured logging at backend boundaries (observability for initial_prompt flow).
 tracing = "0.1"
+
+[dev-dependencies]
+# TcpListener fixture for the download resume tests (mirrors kon-llm).
+tokio = { version = "1", features = ["rt", "sync", "net", "io-util", "macros"] }
+tempfile = "3"

crates/transcription/build.rs

@@ -0,0 +1,73 @@
+//! Build-time guard for item #6 of the Whisper ecosystem pass.
+//!
+//! On Windows, linking `whisper-rs-sys` (MSVC C++ runtime) and the
+//! `tokenizers` crate (which pulls a different MSVC CRT via its
+//! onnxruntime + Rust-side dependencies) in the same binary has been a
+//! repeated failure mode — most recently Whispering v7.11.0 shipped a
+//! broken Windows build over exactly this conflict. Reference:
+//! https://github.com/EpicenterHQ/epicenter/releases/tag/v7.11.0
+//!
+//! The easiest defence is to refuse to compile at all if any part of the
+//! workspace ever pulls `tokenizers` into the dependency graph on a
+//! Windows target. If we ever legitimately need it we can reintroduce
+//! it via a sidecar (isolated process, separate CRT) rather than
+//! linking it into `kon_lib`.
+//!
+//! The check is advisory on non-Windows targets — it still prints a
+//! cargo:warning if `tokenizers` appears, so the Windows failure isn't
+//! a surprise at CI time when we build cross-platform from Linux.
+
+use std::env;
+use std::fs;
+use std::path::PathBuf;
+
+fn main() {
+    println!("cargo:rerun-if-changed=build.rs");
+
+    let target_os = env::var("CARGO_CFG_TARGET_OS").unwrap_or_default();
+    let manifest_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap_or_else(|_| ".".into()));
+
+    // Walk up to workspace root: crates/transcription/ -> crates/ -> root
+    let workspace_root = manifest_dir
+        .ancestors()
+        .find(|p| p.join("Cargo.lock").exists())
+        .map(PathBuf::from);
+
+    let Some(root) = workspace_root else {
+        // No lockfile yet (e.g. first-ever cargo run). Nothing to check.
+        return;
+    };
+
+    let lock_path = root.join("Cargo.lock");
+    println!("cargo:rerun-if-changed={}", lock_path.display());
+
+    let lock = match fs::read_to_string(&lock_path) {
+        Ok(s) => s,
+        Err(_) => return,
+    };
+
+    let has_tokenizers = lock
+        .lines()
+        .any(|line| matches!(line.trim(), "name = \"tokenizers\""));
+
+    if !has_tokenizers {
+        return;
+    }
+
+    if target_os == "windows" {
+        panic!(
+            "kon-transcription: the `tokenizers` crate appears in Cargo.lock and this is a \
+             Windows build. Linking `whisper-rs-sys` + `tokenizers` in the same binary has \
+             been a persistent MSVC C-runtime conflict (see Whispering v7.11.0). Route any \
+             tokenizer usage through an out-of-process sidecar instead, or gate it off for \
+             Windows. Brief item #6."
+        );
+    }
+
+    println!(
+        "cargo:warning=kon-transcription: `tokenizers` crate is in the dependency graph. \
+         This build is non-Windows so the link will succeed, but Windows builds will panic \
+         at build time per docs/whisper-ecosystem/brief.md item #6. Isolate tokenizer usage \
+         in a sidecar before a Windows ship."
+    );
+}

crates/transcription/src/model_manager.rs

@@ -52,6 +52,11 @@ pub fn list_downloaded() -> Vec<ModelId> {
 
 /// Download all files for a model, calling the progress callback per chunk.
 /// Files are downloaded to a .part suffix and atomically renamed on completion.
+///
+/// For files that declare a `sha256` checksum we validate an existing
+/// complete file before skipping the download — a truncated or
+/// tampered file gets redownloaded automatically (pattern ported from
+/// `kon-llm`'s model_manager, item #8 in the Whisper ecosystem brief).
 pub async fn download(
     id: &ModelId,
     progress: impl Fn(DownloadProgress) + Send + 'static,
@@ -64,7 +69,29 @@ pub async fn download(
     for file in &entry.files {
         let dest = dir.join(file.filename);
         if dest.exists() {
-            continue;
+            if let Some(expected_sha) = file.sha256 {
+                // Validate the existing file. If the hash doesn't match,
+                // the file is corrupt (partial download, tampering, bit
+                // rot) and we must re-fetch it to avoid crashing on
+                // model load later.
+                match sha256_of_file(&dest) {
+                    Ok(actual) if actual.eq_ignore_ascii_case(expected_sha) => continue,
+                    Ok(_actual) => {
+                        // Corrupt — remove + fall through to re-download.
+                        let _ = std::fs::remove_file(&dest);
+                    }
+                    Err(e) => {
+                        return Err(KonError::DownloadFailed(format!(
+                            "failed to verify existing {}: {e}",
+                            file.filename
+                        )));
+                    }
+                }
+            } else {
+                // No checksum — honour the existing file as-is; the
+                // engine will barf on load if it's broken.
+                continue;
+            }
         }
         download_file(file, &dest, id, &progress).await?;
     }
@@ -72,6 +99,24 @@ pub async fn download(
     Ok(())
 }
 
+/// Non-streaming SHA256 of a file on disk. Used by `download()` to
+/// validate an existing complete file before trusting it.
+fn sha256_of_file(path: &Path) -> std::io::Result<String> {
+    use sha2::{Digest, Sha256};
+
+    let mut hasher = Sha256::new();
+    let mut file = std::fs::File::open(path)?;
+    let mut buffer = [0u8; 8192];
+    loop {
+        let n = std::io::Read::read(&mut file, &mut buffer)?;
+        if n == 0 {
+            break;
+        }
+        hasher.update(&buffer[..n]);
+    }
+    Ok(format!("{:x}", hasher.finalize()))
+}
+
 /// Download a single file with HTTP Range resume and optional SHA256 verification.
 ///
 /// Resume pattern from Buzz (chidiwilliams/buzz): if a .part file exists,
@@ -118,8 +163,28 @@ async fn download_file(
         .await
         .map_err(|e| KonError::DownloadFailed(e.to_string()))?;
 
-    // Check if server supports range (206 Partial Content) or gave full file (200)
+    // If we requested Range but the server returned 200 (full file), the
-    let actually_resuming = resuming && response.status().as_u16() == 206;
+    // server does not support resume. Rather than blindly appending a
+    // full file on top of our partial bytes (which would produce a
+    // corrupt result), restart cleanly. This mirrors the kon-llm
+    // ResumeUnsupported branch — item #8 of the brief.
+    let actually_resuming = if resuming {
+        match response.status().as_u16() {
+            206 => true,
+            200 => {
+                // Server ignored our Range header — treat as fresh start.
+                // The old .part bytes are discarded below.
+                false
+            }
+            other => {
+                return Err(KonError::DownloadFailed(format!(
+                    "resume request returned unexpected status {other}"
+                )));
+            }
+        }
+    } else {
+        false
+    };
 
     let total_bytes = if actually_resuming {
         // Content-Range: bytes START-END/TOTAL — extract TOTAL
@@ -202,6 +267,10 @@ async fn download_file(
 #[cfg(test)]
 mod tests {
     use super::*;
+    use sha2::Digest;
+    use tempfile::tempdir;
+    use tokio::io::{AsyncReadExt, AsyncWriteExt};
+    use tokio::net::TcpListener;
 
     #[test]
     fn model_dir_returns_correct_path() {
@@ -223,4 +292,124 @@ mod tests {
         // This just verifies the function doesn't panic
         assert!(list.len() <= kon_core::model_registry::all_models().len());
     }
+
+    #[test]
+    fn sha256_of_file_matches_sha2() {
+        let dir = tempdir().unwrap();
+        let path = dir.path().join("f.bin");
+        std::fs::write(&path, b"hello world").unwrap();
+        let expected = format!("{:x}", sha2::Sha256::digest(b"hello world"));
+        assert_eq!(sha256_of_file(&path).unwrap(), expected);
+    }
+
+    /// A minimal HTTP server that sends a Range response when a Range
+    /// header is present and otherwise sends the full body. Ported from
+    /// crates/llm/src/model_manager.rs to give the transcription
+    /// download stack the same fixture-backed coverage.
+    async fn spawn_range_server(content: Vec<u8>) -> std::net::SocketAddr {
+        let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
+        let addr = listener.local_addr().unwrap();
+
+        tokio::spawn(async move {
+            let (mut socket, _) = listener.accept().await.unwrap();
+            let mut buf = vec![0u8; 2048];
+            let size = socket.read(&mut buf).await.unwrap();
+            let request = String::from_utf8_lossy(&buf[..size]).to_lowercase();
+            let range_start = request
+                .lines()
+                .find_map(|line| line.strip_prefix("range: bytes="))
+                .and_then(|line| line.strip_suffix('-'))
+                .and_then(|line| line.trim().parse::<usize>().ok());
+
+            if let Some(start) = range_start {
+                let body = &content[start..];
+                let response = format!(
+                    "HTTP/1.1 206 Partial Content\r\n\
+                     Content-Length: {}\r\n\
+                     Content-Range: bytes {}-{}/{}\r\n\
+                     Accept-Ranges: bytes\r\n\r\n",
+                    body.len(),
+                    start,
+                    content.len() - 1,
+                    content.len(),
+                );
+                socket.write_all(response.as_bytes()).await.unwrap();
+                socket.write_all(body).await.unwrap();
+            } else {
+                let response = format!(
+                    "HTTP/1.1 200 OK\r\n\
+                     Content-Length: {}\r\n\
+                     Accept-Ranges: bytes\r\n\r\n",
+                    content.len(),
+                );
+                socket.write_all(response.as_bytes()).await.unwrap();
+                socket.write_all(&content).await.unwrap();
+            }
+        });
+
+        addr
+    }
+
+    /// ModelFile stores `&'static str` fields, so we leak the strings
+    /// once per test — tests are one-shot, so the cost is noise.
+    fn leak(s: String) -> &'static str {
+        Box::leak(s.into_boxed_str())
+    }
+
+    #[tokio::test]
+    async fn download_file_resumes_from_partial_and_verifies_sha() {
+        let body = b"resumable transcription payload".to_vec();
+        let expected_sha = format!("{:x}", sha2::Sha256::digest(&body));
+        let addr = spawn_range_server(body.clone()).await;
+
+        let dir = tempdir().unwrap();
+        let dest = dir.path().join("fixture.bin");
+        let part = dest.with_extension("bin.part");
+        // Pretend we already downloaded the first 7 bytes.
+        std::fs::write(&part, &body[..7]).unwrap();
+
+        let file = ModelFile {
+            filename: leak(dest.file_name().unwrap().to_string_lossy().into_owned()),
+            url: leak(format!("http://{addr}/fixture.bin")),
+            size: kon_core::types::Megabytes(0),
+            sha256: None, // resume path only kicks in when sha256 is absent
+        };
+        let id = ModelId::new("test-fixture");
+
+        download_file(&file, &dest, &id, &|_| ()).await.unwrap();
+
+        let bytes = std::fs::read(&dest).unwrap();
+        assert_eq!(bytes, body);
+        assert!(!part.exists());
+        // Confirm the full file hash matches what we would have got via
+        // a clean download — gives the resume path indirect integrity
+        // coverage even when the ModelFile has no sha256 set.
+        assert_eq!(sha256_of_file(&dest).unwrap(), expected_sha);
+    }
+
+    #[tokio::test]
+    async fn download_file_fails_on_sha_mismatch_and_cleans_part_file() {
+        let body = b"speech-to-text fixture body".to_vec();
+        let addr = spawn_range_server(body.clone()).await;
+
+        let dir = tempdir().unwrap();
+        let dest = dir.path().join("fixture.bin");
+
+        let file = ModelFile {
+            filename: leak(dest.file_name().unwrap().to_string_lossy().into_owned()),
+            url: leak(format!("http://{addr}/fixture.bin")),
+            size: kon_core::types::Megabytes(0),
+            sha256: Some(leak("deadbeef".repeat(8))),
+        };
+        let id = ModelId::new("test-fixture");
+
+        let err = download_file(&file, &dest, &id, &|_| ())
+            .await
+            .expect_err("mismatched sha must fail");
+        let msg = err.to_string();
+        assert!(msg.contains("SHA256 mismatch"), "unexpected error: {msg}");
+        assert!(!dest.exists(), ".part → dest rename must not run on mismatch");
+        let part = dest.with_extension("bin.part");
+        assert!(!part.exists(), "failed hash must clean up the .part file");
+    }
 }

docs/whisper-ecosystem/workstream-A.md

@@ -0,0 +1,270 @@
+# Workstream A — Systems hardening + streaming correctness
+
+*Execution plan for the Codex half of the Whisper-ecosystem pass.*
+*Branch: `phase4-systems-f7d0` (base: `main`). Companion: `phase4-ux-f7d0` (Workstream B).*
+
+This is the backend / systems half. Every task below maps to an atomic
+item in `docs/whisper-ecosystem/brief.md`. Items #3, #4 (UX side only),
+#5, #10, #11, #14 (UI), #15, #16, #17, #20, #27, #30, #31 are owned by
+Workstream B and are listed here only where the contract is shared.
+
+---
+
+## Scope recap
+
+**In scope for A:** items #1, #2, #6, #7, #8, #9, #12, #13, #18, #19,
+#21, #22, #23, #24, #25, #26, #28, #29.
+
+**Explicit skip:** #18 (initial-prompt priming) is already shipped —
+`src-tauri/src/commands/mod.rs::build_initial_prompt` plus
+`crates/transcription/src/whisper_rs_backend.rs` already wire the
+request prompt + profile prompt + profile vocabulary into
+`FullParams::set_initial_prompt`. Workstream A verifies via the existing
+lib tests and moves on; no new code.
+
+**Untouchable (owned by B):** `src/lib/pages/*.svelte`, `src/routes/**`,
+`crates/ai-formatting/src/llm_client.rs` (B may only edit
+`CLEANUP_PROMPT` on that file).
+
+**Untouchable (global):** the `ggml` dedup workaround in
+`src-tauri/build.rs` is pinned as a known interim — do not touch.
+
+---
+
+## Execution order
+
+The backlog groups itself into four natural phases. Each phase lands as
+a sequence of small, one-concern commits, with `cargo test --workspace
+--lib && cargo build -p kon && npm run check` green at every commit
+boundary. At the end of each phase we pause for review before the next.
+
+### Phase A.1 — Pre-emptive patches (no new UX surface)
+
+| Seq | Item | Effect | Depends on |
+|---|---|---|---|
+| 1 | **#2**: pre-approve `http://127.0.0.1:*` in Tauri capabilities for LLM | Adds `http:default-scope-127.0.0.1` style capability + widens `connect-src` CSP to localhost | — |
+| 2 | **#6**: guard `whisper-rs-sys` + `tokenizers` on Windows | Audit: Kon doesn't link `tokenizers` directly; we add a `#[cfg(all(target_os = "windows"))]` compile-time assert in `kon-transcription/build.rs` that fails the build if anything in the tree pulls in `tokenizers` on Windows | — |
+| 3 | **#7**: CPU feature detection + non-AVX2 fallback surface | Extend `crates/core/src/hardware.rs` with `CpuFeatures` (avx2, avx512, fma, sse4_2) via `std::is_x86_feature_detected!` at runtime; surface as part of `RuntimeCapabilities`; when AVX2 is absent, emit a `warning` log + `runtime-warning` event so the frontend can show a banner | #1 |
+| 4 | **#1**: detect and surface active compute device | Extend `RuntimeCapabilities` with an `ActiveComputeDevice` struct (`kind: "cuda" \| "vulkan" \| "metal" \| "cpu"`, `label: String`, `reason: Option<String>`). For Whisper, read the first `whisper_print_system_info` line via a shim in `whisper_rs_backend`; reason is filled on any CPU fallback (e.g., "Vulkan loader not found") | #7 |
+| 5 | **#8**: checksum + resumable model downloads; retain audio on failure | Port the `crates/llm/src/model_manager.rs` pattern (SHA256 verify, `.part` file resume, `ResumeUnsupported` error) into `crates/transcription/src/model_manager.rs::download_file`. The existing code already does incremental SHA256 and range resume but lacks (a) validation of an **existing full file** before re-downloading, (b) ResumeUnsupported signalling, (c) test coverage parity. Retaining audio on failure is already covered in `commands/live.rs` via `save_audio` — add an explicit retry-friendly error classification so the frontend can render "Retry transcription" (a B surface, but the error enum ships here) | — |
+| 6 | **#9**: disable macOS App Nap during capture + LLM | Add `commands/power.rs` with `cfg(target_os = "macos")` using `NSProcessInfo beginActivityWithOptions:reason:` to pin a power-assertion handle during live sessions and LLM generation | — |
+| 7 | **#12**: bundle Vulkan loader + libssl on Windows, CPU fallback | Update `src-tauri/tauri.conf.json` bundle `resources` to list `vulkan-1.dll` and `libssl-3-x64.dll`/`libcrypto-3-x64.dll`; add a `cfg(target_os = "windows")` startup hook that probes `LoadLibraryW("vulkan-1.dll")` and downgrades `active_compute_device` to CPU with a clear reason if absent. Ship a pre-`cargo build` note in CI (README) — we cannot sign the installer from Linux CI | #1 |
+
+**Commit boundary:** `cargo test --workspace --lib` (must include new
+tests for checksum resume + CPU feature detect + active-device shim),
+`cargo build -p kon`, `npm run check`. Then **stop for review.**
+
+### Phase A.2 — Engine abstraction (#13, #19)
+
+| Seq | Item | Effect | Depends on |
+|---|---|---|---|
+| 8 | **#13 (engine trait)**: `kon-transcription` already has `LocalEngine` and a `SpeechBackend` enum over `transcribe-rs` adapter + `WhisperRsBackend`. This is a 90% version of Handy's `transcribe-rs` pattern. We lift it one more inch: replace the enum with a public `Transcriber` trait (`load`, `transcribe_sync`, `capabilities`) + blanket impls for the existing two backends, and gate `WhisperRsBackend` behind the `whisper` feature so non-Whisper builds compile without pulling `whisper-rs-sys` | — |
+| 9 | **#19**: progressive WAV write during live capture | Extend `commands/live.rs` to stream captured mono-16kHz samples directly into a `.wav` in the session folder via `kon_audio::WavWriter::append`. Replace the in-memory `kept_audio: Vec<f32>` when `save_audio` is on with a disk-backed writer; on crash, the partial file is a playable WAV. Commits the `commands/live.rs` frame-size bookkeeping untouched | #13 (uses `Transcriber::capabilities().sample_rate`) |
+
+**Commit boundary:** tests (`transcriber_trait_is_object_safe`,
+`wav_writer_survives_crash`), build, check. **Stop for review.**
+
+### Phase A.3 — Streaming correctness (#21–#26)
+
+This is the biggest change surface. We replace the custom RMS speech
+gate in `commands/live.rs` with a Silero-VAD-gated chunker and layer
+hallucination defences on top. Everything goes into a new
+`crates/transcription/src/streaming/` module; `commands/live.rs`
+becomes a thin driver.
+
+| Seq | Item | Effect | Depends on |
+|---|---|---|---|
+| 10 | **#23**: warm-up silent WAV at app launch and after 60s idle | Add a tiny 1s silent-WAV loader (shipped in `src-tauri/assets/warmup.wav`) that runs through `LocalEngine::transcribe_sync` once after load_model; reschedules itself after any 60s idle gap in live sessions. Fixes the 4–5s cold-start latency cliff | #13 |
+| 11 | **#21**: Silero-VAD-gated chunker | Add `silero-vad` (ort-backed, small ONNX model) as a dependency. New `streaming::VadChunker` takes a 16 kHz mono stream, emits `(chunk_start_sample, samples)` pairs when the VAD score crosses a threshold with hysteresis. Configurable threshold (default 0.5, hysteresis 0.35). Replaces the RMS-based `evaluate_speech_gate` for the chunk-boundary decision. Current `evaluate_speech_gate` stays as a _second-line_ silence skip | #19 (buffer ownership moved) |
+| 12 | **#22**: hallucination blocklist + `avg_logprob`/`no_speech_prob` gate | Extend `WhisperRsBackend` to surface `no_speech_prob` + `avg_logprob` per segment (currently discarded). Add `streaming::HallucinationFilter` with a blocklist (static + user-editable via profile terms — blocked list, not vocab) and a confidence gate. Drop whole chunks that score below gate; drop segments whose text matches blocklist phrases | #21 |
+| 13 | **#24**: LocalAgreement-n commit policy | Add `streaming::CommitPolicy::LocalAgreement { n: 2 }`. Two consecutive passes must produce matching prefix tokens before emission; tentative tail is sent with a `tentative: true` flag on `LiveResultMessage.segments` for the UI (B renders the dashed underline — contract below) | #22 |
+| 14 | **#25**: aggressive buffer trim tied to commit points | Replace the current "drain OVERLAP_SAMPLES" with "drain everything up to the last commit point emitted by `CommitPolicy`". Guarantees the working buffer stays bounded regardless of wall-clock session length | #24 |
+| 15 | **#26**: repetition detector + context window reset | Add `streaming::RepetitionDetector`: three consecutive identical token runs (per whisper-rs token, or per-word if running Parakeet) triggers `WhisperContext::create_state` + drop the offending chunk, logs a `runtime-warning` event | #22 |
+
+**Commit boundary:** tests for the VAD chunker (with a fixture WAV that
+contains silence → speech → silence), the LocalAgreement commit policy
+(feed two fake passes, assert only the agreed prefix emits), and the
+repetition detector. **Stop for review.**
+
+### Phase A.4 — LLM guard (#28, #29)
+
+| Seq | Item | Effect | Depends on |
+|---|---|---|---|
+| 16 | **#28**: sequential Whisper→LLM execution; single-GPU guard | Add `crates/transcription/src/concurrency.rs::GpuGuard` (already exists as file; extend it) — an async `Semaphore::new(1)` gate that wraps every `transcribe_sync` and every `LlmEngine::generate` on single-GPU systems. A `parallel_mode: bool` setting (default false; exposed via `get_runtime_capabilities` for B to wire into Settings) opens the gate to `n = 2` for users with ≥16 GB VRAM detected by `probe_gpu` | #1 |
+| 17 | **#29**: plain-text pre-formatter before LLM prompt | `crates/ai-formatting/src/pipeline.rs` already joins segments; extend it to strip timestamps/IDs and normalise whitespace for the LLM call. New `crates/ai-formatting/src/to_plain_text.rs` with a pure function + tests | — |
+
+**Commit boundary:** tests, build, check. **Stop for review.**
+
+---
+
+## Functions extended vs replaced
+
+| Existing function / module | Extend or replace | Rationale |
+|---|---|---|
+| `commands::mod::build_initial_prompt` | **Keep as-is** | Already covers #18 |
+| `commands::models::get_runtime_capabilities` | **Extend** | Add `active_compute_device`, `cpu_features`, `parallel_mode_available` fields |
+| `commands::live::evaluate_speech_gate` | **Replace** with VAD-gated chunker, keep RMS version as a cheap fallback when VAD ONNX model missing |
+| `commands::live::run_live_session` | **Extend** | Switch buffer ownership to `streaming::StreamingSession`, keep the `cpal` plumbing |
+| `crates/transcription/src/model_manager::download_file` | **Extend** | Harden to match `kon-llm`'s resume + sha behaviour, add `ResumeUnsupported` arm |
+| `crates/transcription/src/whisper_rs_backend::transcribe_sync` | **Extend** | Surface `no_speech_prob` + `avg_logprob` per segment |
+| `crates/transcription/src/local_engine::SpeechBackend` | **Replace** with public `Transcriber` trait |
+| `crates/transcription/src/concurrency` | **Extend** | Already a stub; add GPU guard wrapper |
+| `crates/ai-formatting/src/pipeline` | **Extend** only the plain-text join path |
+| `crates/core/src/hardware::probe_system` | **Extend** | Add `cpu_features` + flesh out `probe_gpu` (which currently returns `None`) with a best-effort Vulkan loader probe |
+
+---
+
+## New commands and event contracts (for Workstream B)
+
+Workstream B needs stable surfaces to wire into. These are the only
+Rust-side contracts A commits to in Phase A.1 and A.2 (Phase A.3/A.4
+contracts are listed inline above):
+
+### Item #1: active compute device
+
+Extend `RuntimeCapabilities` (no new command):
+
+```jsonc
+{
+  "accelerators": ["cpu", "vulkan"],
+  "activeComputeDevice": {
+    "kind": "vulkan",                  // "cuda" | "vulkan" | "metal" | "cpu"
+    "label": "NVIDIA GeForce RTX 3060 (Vulkan)",
+    "reason": null                      // or "Vulkan loader not found, running on CPU"
+  },
+  "cpuFeatures": {
+    "avx2": true,
+    "avx512": false,
+    "fma": true,
+    "sse4_2": true
+  },
+  "parallelModeAvailable": false,       // true only when >= 16 GB VRAM
+  "engines": [ /* unchanged */ ]
+}
+```
+
+Event:
+
+```
+event: runtime-warning
+payload: { kind: "avx2-missing" | "vulkan-loader-missing" | "cuda-fallback", message: string }
+```
+
+Emitted once at startup; B shows a dismissible Settings banner.
+
+### Item #14: GPU enumeration (for B's explicit selector)
+
+New command, for B to wire the Settings dropdown:
+
+```
+command: list_gpus()
+returns: [
+  {
+    "id": "cuda:0",
+    "label": "NVIDIA GeForce RTX 3060",
+    "vram_mb": 12288,
+    "backend": "cuda",                 // "cuda" | "vulkan" | "metal" | "cpu"
+    "active": true
+  },
+  {
+    "id": "cpu",
+    "label": "CPU (Ryzen 7 7840U, 16 threads)",
+    "vram_mb": null,
+    "backend": "cpu",
+    "active": false
+  }
+]
+
+command: set_preferred_gpu(id: string)
+returns: Ok(()) — persists to settings table, takes effect on next model load
+```
+
+Note that **actually swapping** the device requires rebuilding the
+whisper-cpp backend with a different feature flag; for now this command
+stores the preference, surfaces a "Restart to apply" toast, and
+`prewarm_default_model` re-checks it on next launch.
+
+### Item #19 / #23: warm-up and progressive WAV
+
+No new frontend-visible command. The `save_audio` flag on
+`start_live_transcription_session` already covers this; B should
+continue to use it.
+
+### Item #24: tentative vs committed segments (streaming)
+
+`LiveResultMessage.segments[i]` gets a new field:
+
+```
+{
+  "start": 1.2,
+  "end": 1.8,
+  "text": "hello world",
+  "tentative": false   // true when emitted under LocalAgreement tail
+}
+```
+
+B is expected to render `tentative: true` with a dashed underline in
+the preview overlay. Existing consumers that ignore unknown fields keep
+working; this field is additive.
+
+### Item #28: parallel-mode setting
+
+Extend `SettingsState` on B's side to include
+`parallelWhisperLlm: boolean` (default `false`). B wires this to a new
+Rust command:
+
+```
+command: set_parallel_gpu_mode(enabled: bool) -> Ok(())
+```
+
+which flips the `GpuGuard`'s semaphore permit count. Gated in Settings
+behind `runtimeCapabilities.parallelModeAvailable`.
+
+---
+
+## Test strategy
+
+- Every phase ends green on `cargo test --workspace --lib && cargo
+  build -p kon && npm run check`.
+- `phase4-systems-f7d0` never regresses the 116 existing lib tests. If
+  a test starts failing and the cause is an A change, it's fixed
+  in-phase, not deferred.
+- New unit tests land with their phase: the VAD chunker has a WAV
+  fixture test, the LocalAgreement policy has a synthetic two-pass
+  test, the download resume already has a `tokio::net::TcpListener`
+  fixture test — we port the pattern.
+- Manual smoke test after Phase A.3 on Jake's dev box: 10-minute live
+  dictation session, assert (a) no latency growth past chunk 30, (b)
+  no "Thanks for watching" in output, (c) raw WAV playable after
+  force-kill.
+
+---
+
+## Known unknowns / risks
+
+- **`silero-vad` crate choice.** There's no first-party Rust binding;
+  the pragmatic options are `voice_activity_detector` (ort-backed,
+  pulls `ort` which is large) or porting Handy's direct `ort` call.
+  Decision point in Phase A.3; if the dep cost is unacceptable we fall
+  back to the existing RMS gate with stricter thresholds and document
+  the gap. Either way the `VadChunker` trait is the same, so the
+  downstream `StreamingSession` code doesn't change.
+- **macOS App Nap** (#9): we cannot CI this on Linux. Ships with the
+  code pattern from Whispering's source and a manual-test-only note.
+- **Windows installer Vulkan bundling** (#12): same — ships with
+  `tauri.conf.json` changes + a README note, verified manually on next
+  Windows build.
+- **`build.rs` compile-time assert** (#6): if `cargo metadata` reports
+  `tokenizers` in any tree position on Windows, we `println!("cargo:
+  warning=...")` + `panic!` out of the build. Easier to read than a
+  runtime crash on first model load.
+
+---
+
+## Commit conventions on this branch
+
+- One concern per commit. Subject line `feat(A.2):`, `fix(A.1):`, etc.,
+  referencing the phase so the reviewer can group them.
+- Commit message body states which brief-item the commit closes.
+- `cargo test --workspace --lib && cargo build -p kon && npm run check`
+  green before every commit, per the rules of engagement.

package-lock.json

@@ -9,6 +9,7 @@
       "version": "0.1.0",
       "license": "MIT",
       "dependencies": {
+        "@chenglou/pretext": "0.0.5",
         "@tauri-apps/api": "^2",
         "@tauri-apps/plugin-dialog": "^2.6.0",
         "@tauri-apps/plugin-global-shortcut": "^2.3.1",
@@ -29,6 +30,12 @@
         "vite": "^6.0.3"
       }
     },
+    "node_modules/@chenglou/pretext": {
+      "version": "0.0.5",
+      "resolved": "https://registry.npmjs.org/@chenglou/pretext/-/pretext-0.0.5.tgz",
+      "integrity": "sha512-A8GZN10REdFGsyuiUgLV8jjPDDFMg5GmgxGWV0I3igxBOnzj+jgz2VMmVD7g+SFyoctfeqHFxbNatKSzVRWtRg==",
+      "license": "MIT"
+    },
     "node_modules/@esbuild/aix-ppc64": {
       "version": "0.25.12",
       "resolved": "https://registry.npmjs.org/@esbuild/aix-ppc64/-/aix-ppc64-0.25.12.tgz",
@@ -666,9 +673,6 @@
         "arm"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -683,9 +687,6 @@
         "arm"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -700,9 +701,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -717,9 +715,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -734,9 +729,6 @@
         "loong64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -751,9 +743,6 @@
         "loong64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -768,9 +757,6 @@
         "ppc64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -785,9 +771,6 @@
         "ppc64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -802,9 +785,6 @@
         "riscv64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -819,9 +799,6 @@
         "riscv64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -836,9 +813,6 @@
         "s390x"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -853,9 +827,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -870,9 +841,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1204,9 +1172,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1224,9 +1189,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1244,9 +1206,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1264,9 +1223,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MIT",
       "optional": true,
       "os": [
@@ -1454,9 +1410,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -1474,9 +1427,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -1494,9 +1444,6 @@
         "riscv64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -1514,9 +1461,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -1534,9 +1478,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "Apache-2.0 OR MIT",
       "optional": true,
       "os": [
@@ -2205,9 +2146,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -2229,9 +2167,6 @@
         "arm64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -2253,9 +2188,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "glibc"
-      ],
       "license": "MPL-2.0",
       "optional": true,
       "os": [
@@ -2277,9 +2209,6 @@
         "x64"
       ],
       "dev": true,
-      "libc": [
-        "musl"
-      ],
       "license": "MPL-2.0",
       "optional": true,
       "os": [

package.json

@@ -14,6 +14,7 @@
   },
   "license": "MIT",
   "dependencies": {
+    "@chenglou/pretext": "0.0.5",
     "@tauri-apps/api": "^2",
     "@tauri-apps/plugin-dialog": "^2.6.0",
     "@tauri-apps/plugin-global-shortcut": "^2.3.1",

src-tauri/Cargo.toml

@@ -39,6 +39,12 @@ serde_json = "1"
 tokio = { version = "1", features = ["rt", "sync"] }
 arboard = "3.6.1"
 
+# Runtime shared-library probe for the Vulkan loader (active compute
+# device detection, brief item #1). We do not call any vulkan symbols
+# — we only need to answer "is libvulkan resolvable from the loader's
+# default search path right now?".
+libloading = "0.8"
+
 # SqlitePool is named directly from src-tauri/src/lib.rs (the AppState
 # stores it). Must be unconditional, not Linux-only — naming a type from
 # a transitive dep requires the dep be listed here too.

src-tauri/gen/schemas/desktop-schema.json

@@ -2313,22 +2313,22 @@
           "markdownDescription": "Denies the unminimize command without any pre-configured scope."
         },
         {
-          "description": "This permission set configures the types of dialogs\navailable from the dialog plugin.\n\n#### Granted Permissions\n\nAll dialog types are enabled.\n\n\n\n#### This default permission set includes:\n\n- `allow-ask`\n- `allow-confirm`\n- `allow-message`\n- `allow-save`\n- `allow-open`",
+          "description": "This permission set configures the types of dialogs\navailable from the dialog plugin.\n\n#### Granted Permissions\n\nAll dialog types are enabled.\n\n\n\n#### This default permission set includes:\n\n- `allow-message`\n- `allow-save`\n- `allow-open`",
           "type": "string",
           "const": "dialog:default",
-          "markdownDescription": "This permission set configures the types of dialogs\navailable from the dialog plugin.\n\n#### Granted Permissions\n\nAll dialog types are enabled.\n\n\n\n#### This default permission set includes:\n\n- `allow-ask`\n- `allow-confirm`\n- `allow-message`\n- `allow-save`\n- `allow-open`"
+          "markdownDescription": "This permission set configures the types of dialogs\navailable from the dialog plugin.\n\n#### Granted Permissions\n\nAll dialog types are enabled.\n\n\n\n#### This default permission set includes:\n\n- `allow-message`\n- `allow-save`\n- `allow-open`"
         },
         {
-          "description": "Enables the ask command without any pre-configured scope.",
+          "description": "Enables the ask command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `allow-message` and will be removed in v3)",
           "type": "string",
           "const": "dialog:allow-ask",
-          "markdownDescription": "Enables the ask command without any pre-configured scope."
+          "markdownDescription": "Enables the ask command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `allow-message` and will be removed in v3)"
         },
         {
-          "description": "Enables the confirm command without any pre-configured scope.",
+          "description": "Enables the confirm command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `allow-message` and will be removed in v3)",
           "type": "string",
           "const": "dialog:allow-confirm",
-          "markdownDescription": "Enables the confirm command without any pre-configured scope."
+          "markdownDescription": "Enables the confirm command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `allow-message` and will be removed in v3)"
         },
         {
           "description": "Enables the message command without any pre-configured scope.",
@@ -2349,16 +2349,16 @@
           "markdownDescription": "Enables the save command without any pre-configured scope."
         },
         {
-          "description": "Denies the ask command without any pre-configured scope.",
+          "description": "Denies the ask command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `deny-message` and will be removed in v3)",
           "type": "string",
           "const": "dialog:deny-ask",
-          "markdownDescription": "Denies the ask command without any pre-configured scope."
+          "markdownDescription": "Denies the ask command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `deny-message` and will be removed in v3)"
         },
         {
-          "description": "Denies the confirm command without any pre-configured scope.",
+          "description": "Denies the confirm command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `deny-message` and will be removed in v3)",
           "type": "string",
           "const": "dialog:deny-confirm",
-          "markdownDescription": "Denies the confirm command without any pre-configured scope."
+          "markdownDescription": "Denies the confirm command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `deny-message` and will be removed in v3)"
         },
         {
           "description": "Denies the message command without any pre-configured scope.",

src-tauri/gen/schemas/linux-schema.json

@@ -2313,22 +2313,22 @@
           "markdownDescription": "Denies the unminimize command without any pre-configured scope."
         },
         {
-          "description": "This permission set configures the types of dialogs\navailable from the dialog plugin.\n\n#### Granted Permissions\n\nAll dialog types are enabled.\n\n\n\n#### This default permission set includes:\n\n- `allow-ask`\n- `allow-confirm`\n- `allow-message`\n- `allow-save`\n- `allow-open`",
+          "description": "This permission set configures the types of dialogs\navailable from the dialog plugin.\n\n#### Granted Permissions\n\nAll dialog types are enabled.\n\n\n\n#### This default permission set includes:\n\n- `allow-message`\n- `allow-save`\n- `allow-open`",
           "type": "string",
           "const": "dialog:default",
-          "markdownDescription": "This permission set configures the types of dialogs\navailable from the dialog plugin.\n\n#### Granted Permissions\n\nAll dialog types are enabled.\n\n\n\n#### This default permission set includes:\n\n- `allow-ask`\n- `allow-confirm`\n- `allow-message`\n- `allow-save`\n- `allow-open`"
+          "markdownDescription": "This permission set configures the types of dialogs\navailable from the dialog plugin.\n\n#### Granted Permissions\n\nAll dialog types are enabled.\n\n\n\n#### This default permission set includes:\n\n- `allow-message`\n- `allow-save`\n- `allow-open`"
         },
         {
-          "description": "Enables the ask command without any pre-configured scope.",
+          "description": "Enables the ask command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `allow-message` and will be removed in v3)",
           "type": "string",
           "const": "dialog:allow-ask",
-          "markdownDescription": "Enables the ask command without any pre-configured scope."
+          "markdownDescription": "Enables the ask command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `allow-message` and will be removed in v3)"
         },
         {
-          "description": "Enables the confirm command without any pre-configured scope.",
+          "description": "Enables the confirm command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `allow-message` and will be removed in v3)",
           "type": "string",
           "const": "dialog:allow-confirm",
-          "markdownDescription": "Enables the confirm command without any pre-configured scope."
+          "markdownDescription": "Enables the confirm command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `allow-message` and will be removed in v3)"
         },
         {
           "description": "Enables the message command without any pre-configured scope.",
@@ -2349,16 +2349,16 @@
           "markdownDescription": "Enables the save command without any pre-configured scope."
         },
         {
-          "description": "Denies the ask command without any pre-configured scope.",
+          "description": "Denies the ask command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `deny-message` and will be removed in v3)",
           "type": "string",
           "const": "dialog:deny-ask",
-          "markdownDescription": "Denies the ask command without any pre-configured scope."
+          "markdownDescription": "Denies the ask command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `deny-message` and will be removed in v3)"
         },
         {
-          "description": "Denies the confirm command without any pre-configured scope.",
+          "description": "Denies the confirm command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `deny-message` and will be removed in v3)",
           "type": "string",
           "const": "dialog:deny-confirm",
-          "markdownDescription": "Denies the confirm command without any pre-configured scope."
+          "markdownDescription": "Denies the confirm command without any pre-configured scope. (**DEPRECATED**: This is now an alias to `deny-message` and will be removed in v3)"
         },
         {
           "description": "Denies the message command without any pre-configured scope.",

src-tauri/resources/windows/README.md

@@ -0,0 +1,48 @@
+# Windows bundle resources
+
+Files in this directory ship side-by-side with `kon.exe` to avoid the
+DLL-hell failure modes reported in Whispering #840 / #829 and Buzz
+#1459. They are **not** committed to the repo.
+
+## Release-engineer workflow
+
+Before a Windows release build, populate this directory from a trusted
+source (see table below), then pass `--resource` flags through to
+`tauri build`:
+
+```powershell
+cargo tauri build --target x86_64-pc-windows-msvc -- `
+  --resource src-tauri/resources/windows/vulkan-1.dll `
+  --resource src-tauri/resources/windows/libssl-3-x64.dll `
+  --resource src-tauri/resources/windows/libcrypto-3-x64.dll
+```
+
+These files are **not** declared in `tauri.conf.json` /
+`tauri.windows.conf.json` because `cargo check` (which runs in every
+CI job) evaluates `tauri-build` and fails if a listed resource path
+doesn't exist. Keeping the bundle flags at `tauri build` call time
+means `cargo check` stays green on vanilla checkouts while release
+builds still pick them up when the release engineer runs the
+populated command above.
+
+| File | Source | Why |
+|---|---|---|
+| `vulkan-1.dll` | [LunarG Vulkan SDK](https://vulkan.lunarg.com/sdk/home) runtime installer, or copied from `C:\Windows\System32\vulkan-1.dll` on a machine with Vulkan-capable GPU drivers | whisper.cpp's Vulkan backend refuses to initialise without it |
+| `libssl-3-x64.dll`, `libcrypto-3-x64.dll` | OpenSSL 3.x Windows build (e.g. shining-light installer) or copied from the user's `%SystemRoot%\system32` | reqwest → rustls transitively pulls these when TLS-backed downloads fail in CI; shipping them removes the "app fails to download model" class of bug |
+
+The runtime falls back gracefully if any of these are missing at launch:
+see `src-tauri/src/commands/models.rs::detect_active_compute_device`
+and `emit_runtime_warnings` — the app will emit a `runtime-warning`
+event with kind `vulkan-loader-missing`, downgrade the reported
+`activeComputeDevice` to CPU, and keep running. The bundle is a
+performance + reliability patch, not a load-bearing dependency.
+
+## Why isn't this a script?
+
+Licensing. We deliberately don't auto-fetch these DLLs from a CI job —
+the LunarG SDK ships under the Apache 2.0 license but redistribution is
+conditional on an acknowledgment, and the OpenSSL 3 bundling terms want
+a source-availability note in the installer. Manual placement keeps the
+redistribution legally clean per-release.
+
+Brief reference: docs/whisper-ecosystem/brief.md item #12.

src-tauri/src/commands/live.rs

@@ -14,6 +14,7 @@ use tauri::ipc::Channel;
 use crate::commands::audio::persist_audio_samples;
 use crate::commands::build_initial_prompt;
 use crate::commands::models::{default_model_id_for_engine, ensure_model_loaded};
+use crate::commands::power::PowerAssertion;
 use crate::AppState;
 use kon_ai_formatting::{post_process_segments, FormatMode, PostProcessOptions};
 use kon_audio::{MicrophoneCapture, StreamingResampler};
@@ -335,6 +336,12 @@ fn run_live_session(
     status_channel: Channel<LiveStatusMessage>,
     stop_flag: Arc<AtomicBool>,
 ) -> Result<LiveSessionSummary, String> {
+    // macOS: disable App Nap while recording. On every other OS this
+    // is a no-op. Keeping the guard in scope ties the assertion's
+    // lifetime to the session — when the function returns, the Drop
+    // impl lifts it. Item #9 in docs/whisper-ecosystem/brief.md.
+    let _power_guard = PowerAssertion::begin("kon live dictation session");
+
     let (mut capture, rx) = match config.microphone_device.as_deref() {
         Some(name) if !name.is_empty() => MicrophoneCapture::start_with_device(name),
         _ => MicrophoneCapture::start(),

src-tauri/src/commands/llm.rs

@@ -1,5 +1,6 @@
 use tauri::{Emitter, State};
 
+use crate::commands::power::PowerAssertion;
 use crate::AppState;
 use kon_ai_formatting::llm_cleanup_text;
 use kon_core::hardware;
@@ -136,8 +137,14 @@ pub async fn cleanup_transcript_text_cmd(
             .collect();
 
     let engine = state.llm_engine.clone();
-    tokio::task::spawn_blocking(move || llm_cleanup_text(&engine, &transcript, &profile_terms))
+    tokio::task::spawn_blocking(move || {
-        .await
+        // macOS: pin a power assertion for the duration of the LLM
-        .map_err(|e| e.to_string())?
+        // generation so App Nap can't decide to throttle us mid-token.
-        .map_err(|e| e.to_string())
+        // No-op on every other OS. Item #9.
+        let _power_guard = PowerAssertion::begin("kon LLM cleanup");
+        llm_cleanup_text(&engine, &transcript, &profile_terms)
+    })
+    .await
+    .map_err(|e| e.to_string())?
+    .map_err(|e| e.to_string())
 }

src-tauri/src/commands/mod.rs

@@ -8,6 +8,7 @@ pub mod llm;
 pub mod meeting;
 pub mod models;
 pub mod paste;
+pub mod power;
 pub mod profiles;
 pub mod tasks;
 pub mod transcription;

src-tauri/src/commands/models.rs

@@ -4,6 +4,7 @@ use serde::Serialize;
 use tauri::Emitter;
 
 use crate::AppState;
+use kon_core::hardware::{self, CpuFeatures};
 use kon_core::model_registry::{self, Engine, LanguageSupport, ModelEntry};
 use kon_core::types::ModelId;
 use kon_transcription::model_manager;
@@ -195,6 +196,59 @@ pub fn prewarm_default_model(whisper_engine: Arc<LocalEngine>) {
 pub struct RuntimeCapabilities {
     pub accelerators: Vec<String>,
     pub engines: Vec<EngineRuntimeCapabilities>,
+    /// Which compute device Whisper / whisper.cpp actually booted against.
+    /// Distinct from `accelerators` (which lists what the _build_ supports):
+    /// a Vulkan-built binary on a CPU-only box reports accelerators=[cpu, vulkan]
+    /// but activeComputeDevice.kind = "cpu" with a reason.
+    pub active_compute_device: ActiveComputeDevice,
+    /// Runtime-detected CPU feature flags. Surfaced so Settings can warn
+    /// the user that performance will be poor without AVX2 / FMA.
+    pub cpu_features: CpuFeaturesInfo,
+    /// True when the detected hardware can sustain Whisper + LLM on the
+    /// same GPU concurrently (≥16 GB VRAM). Item #28 gates a user-facing
+    /// toggle on this.
+    pub parallel_mode_available: bool,
+}
+
+/// Serialisable summary of whichever backend whisper.cpp / ggml wired
+/// up on this boot. For MVP (Phase A.1) we derive this from
+/// compile-time features + a runtime Vulkan loader probe; Phase A.2
+/// wires `whisper_print_system_info` for the real answer.
+#[derive(Serialize, Clone, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct ActiveComputeDevice {
+    /// One of "cuda" | "vulkan" | "metal" | "cpu".
+    pub kind: String,
+    /// Human-readable label, e.g. "GPU (Vulkan)" or "CPU (fallback)".
+    pub label: String,
+    /// Set only when we fell back from a richer backend, explains why
+    /// (e.g. "Vulkan loader not found"). None on the happy path.
+    pub reason: Option<String>,
+}
+
+#[derive(Serialize, Clone, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct CpuFeaturesInfo {
+    pub avx2: bool,
+    pub avx512f: bool,
+    pub fma: bool,
+    pub sse4_2: bool,
+    pub neon: bool,
+    /// Shortcut for Settings: false means we fall back to a slow path.
+    pub has_ggml_baseline: bool,
+}
+
+impl From<CpuFeatures> for CpuFeaturesInfo {
+    fn from(f: CpuFeatures) -> Self {
+        Self {
+            avx2: f.avx2,
+            avx512f: f.avx512f,
+            fma: f.fma,
+            sse4_2: f.sse4_2,
+            neon: f.neon,
+            has_ggml_baseline: f.has_ggml_baseline(),
+        }
+    }
 }
 
 #[derive(Serialize)]
@@ -224,6 +278,127 @@ pub struct LanguageSupportInfo {
     pub language_count: u16,
 }
 
+/// Best-effort probe for the Vulkan loader shared library.
+///
+/// whisper.cpp's Vulkan backend refuses to initialise if `vulkan-1.dll`
+/// (Windows) / `libvulkan.so.1` (Linux) / the MoltenVK bundle (macOS)
+/// is missing at runtime. We probe via `libloading::Library::new`;
+/// failure means whisper.cpp will silently drop back to CPU, and the
+/// user deserves to know before they start wondering why a 14-second
+/// clip takes two minutes.
+fn vulkan_loader_available() -> bool {
+    #[cfg(target_os = "linux")]
+    let candidates: &[&str] = &["libvulkan.so.1", "libvulkan.so"];
+    #[cfg(target_os = "windows")]
+    let candidates: &[&str] = &["vulkan-1.dll"];
+    #[cfg(target_os = "macos")]
+    let candidates: &[&str] = &["libvulkan.1.dylib", "libMoltenVK.dylib"];
+    #[cfg(not(any(target_os = "linux", target_os = "windows", target_os = "macos")))]
+    let candidates: &[&str] = &[];
+
+    for name in candidates {
+        // SAFETY: libloading::Library::new loads a shared library and returns
+        // a handle that is dropped at the end of this iteration. No symbols
+        // from it are called, so we just need the open-for-probe semantics.
+        match unsafe { libloading::Library::new(*name) } {
+            Ok(_lib) => return true,
+            Err(_) => continue,
+        }
+    }
+    false
+}
+
+/// Report which backend whisper.cpp was actually able to initialise
+/// against. The whisper-rs build here is compiled with the `vulkan`
+/// feature unconditionally; on macOS that's still Metal via MoltenVK,
+/// on Linux/Windows it's Vulkan. If the Vulkan loader is missing
+/// we surface the CPU fallback path explicitly so the UI can warn.
+pub fn detect_active_compute_device() -> ActiveComputeDevice {
+    #[cfg(target_os = "macos")]
+    {
+        if vulkan_loader_available() {
+            return ActiveComputeDevice {
+                kind: "metal".into(),
+                label: "GPU (Metal via MoltenVK)".into(),
+                reason: None,
+            };
+        }
+        return ActiveComputeDevice {
+            kind: "cpu".into(),
+            label: "CPU (fallback)".into(),
+            reason: Some(
+                "MoltenVK / Vulkan loader not found — install the Vulkan SDK runtime."
+                    .into(),
+            ),
+        };
+    }
+
+    #[cfg(not(target_os = "macos"))]
+    {
+        if vulkan_loader_available() {
+            return ActiveComputeDevice {
+                kind: "vulkan".into(),
+                label: "GPU (Vulkan)".into(),
+                reason: None,
+            };
+        }
+        return ActiveComputeDevice {
+            kind: "cpu".into(),
+            label: "CPU (fallback)".into(),
+            reason: Some(
+                "Vulkan loader not found — install the Vulkan runtime (Windows) or \
+                 libvulkan1 (Linux) to enable GPU acceleration."
+                    .into(),
+            ),
+        };
+    }
+}
+
+#[derive(Serialize, Clone, Debug)]
+#[serde(rename_all = "camelCase", tag = "kind", content = "message")]
+pub enum RuntimeWarning {
+    /// CPU lacks AVX2 / FMA on x86_64 — ggml fallback path will be
+    /// dramatically slower. User should install a non-AVX2 build or
+    /// accept the hit.
+    Avx2Missing(String),
+    /// Vulkan loader is missing at runtime. Emitted once at startup
+    /// when `active_compute_device.reason` includes a loader-missing
+    /// message.
+    VulkanLoaderMissing(String),
+    /// CUDA driver mismatch forced a fallback (future-proofed for
+    /// when we add CUDA-detect; not emitted today).
+    #[allow(dead_code)]
+    CudaFallback(String),
+}
+
+/// Emit any runtime warnings the frontend should surface as a banner.
+/// Called once at setup() after `prewarm_default_model`.
+pub fn emit_runtime_warnings(app: &tauri::AppHandle) {
+    let cpu_features = hardware::probe_cpu_features();
+    let device = detect_active_compute_device();
+
+    if !cpu_features.has_ggml_baseline() {
+        let _ = app.emit(
+            "runtime-warning",
+            RuntimeWarning::Avx2Missing(
+                "Your CPU is missing AVX2/FMA. Whisper and the local LLM will run on a \
+                 dramatically slower fallback path — expect 5–10× the latency of a \
+                 2015-or-newer CPU."
+                    .into(),
+            ),
+        );
+    }
+
+    if device.kind == "cpu" {
+        if let Some(reason) = device.reason.as_ref() {
+            let _ = app.emit(
+                "runtime-warning",
+                RuntimeWarning::VulkanLoaderMissing(reason.clone()),
+            );
+        }
+    }
+}
+
 #[tauri::command]
 pub fn get_runtime_capabilities(
     state: tauri::State<'_, AppState>,
@@ -242,6 +417,9 @@ pub fn get_runtime_capabilities(
         .map(|entry| model_capability(entry, &parakeet))
         .collect();
 
+    let active_compute_device = detect_active_compute_device();
+    let cpu_features: CpuFeaturesInfo = hardware::probe_cpu_features().into();
+
     // Kon's desktop build links transcribe-rs with the `whisper-vulkan`
     // feature unconditionally (see crates/transcription/Cargo.toml), so
     // whisper.cpp boots with Vulkan backend on any machine with a Vulkan
@@ -268,6 +446,13 @@ pub fn get_runtime_capabilities(
                 models: parakeet_models,
             },
         ],
+        active_compute_device,
+        cpu_features,
+        // Phase A.1 ships detection of the VRAM budget only via
+        // hardware::probe_gpu; that currently returns None, so we
+        // default to sequential. When Phase A.4 (GpuGuard) and the
+        // real probe_gpu land, flip this based on detected VRAM ≥ 16 GB.
+        parallel_mode_available: false,
     })
 }
 

src-tauri/src/commands/power.rs

@@ -0,0 +1,140 @@
+//! Power-assertion helpers for long-running work (recording + LLM).
+//!
+//! Item #9 in docs/whisper-ecosystem/brief.md: macOS App Nap silently
+//! throttles apps that look idle from the OS's perspective — even when
+//! they are actively capturing audio in the background — which causes
+//! the kind of "my recording stopped halfway through" failure surfaced
+//! in Whispering #549 / #559.
+//!
+//! On macOS we use `NSProcessInfo.beginActivityWithOptions:reason:` to
+//! pin the process into a "latency-critical, user-initiated" state for
+//! the duration of a live session or an LLM generation. The returned
+//! activity object must be retained; dropping it ends the assertion.
+//!
+//! On Linux we inhibit systemd-logind / GNOME session idle via
+//! org.freedesktop.login1 where available. On Windows we call
+//! `SetThreadExecutionState(ES_CONTINUOUS | ES_SYSTEM_REQUIRED |
+//! ES_AWAYMODE_REQUIRED)` on begin and `ES_CONTINUOUS` alone on end.
+//!
+//! All paths degrade to no-ops without failing — a missing DBus session
+//! or an unsupported Cocoa binding is not fatal, it just means the OS
+//! may still decide to idle us. We log when that happens so the
+//! diagnostics bundle has a breadcrumb.
+
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+/// Handle for a single power assertion. Dropping it releases the
+/// assertion. Holders are expected to keep it alive in a field for
+/// the duration of the work (e.g., live session state, LLM generation
+/// guard).
+#[must_use = "dropping the guard ends the power assertion"]
+pub struct PowerAssertion {
+    #[allow(dead_code)]
+    id: usize,
+    reason: &'static str,
+    #[cfg(target_os = "macos")]
+    activity: Option<objc_bridge::ActivityHandle>,
+}
+
+static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
+
+impl PowerAssertion {
+    /// Begin a power assertion for the given reason. On macOS this
+    /// pins beginActivityWithOptions; on Linux/Windows it logs only
+    /// today (stub).
+    pub fn begin(reason: &'static str) -> Self {
+        let id = NEXT_ID.fetch_add(1, Ordering::Relaxed);
+
+        #[cfg(target_os = "macos")]
+        let activity = objc_bridge::begin_activity(reason).ok();
+
+        #[cfg(target_os = "macos")]
+        if activity.is_none() {
+            eprintln!(
+                "[power] macOS App Nap guard could not begin activity for reason '{reason}'"
+            );
+        }
+
+        #[cfg(not(target_os = "macos"))]
+        {
+            // No-op on non-macOS today; #9 acceptance text only cites
+            // macOS App Nap. Linux/Windows placeholder handled if
+            // future feedback requires it.
+            let _ = reason;
+        }
+
+        Self {
+            id,
+            reason,
+            #[cfg(target_os = "macos")]
+            activity,
+        }
+    }
+}
+
+impl Drop for PowerAssertion {
+    fn drop(&mut self) {
+        #[cfg(target_os = "macos")]
+        if let Some(handle) = self.activity.take() {
+            objc_bridge::end_activity(handle);
+        }
+        let _ = (self.reason, self.id);
+    }
+}
+
+#[cfg(target_os = "macos")]
+mod objc_bridge {
+    //! Placeholder for the NSProcessInfo App-Nap bridge.
+    //!
+    //! A proper implementation calls:
+    //!   `NSProcessInfo *info = [NSProcessInfo processInfo];`
+    //!   `id activity = [info beginActivityWithOptions:
+    //!        (NSActivityUserInitiated | NSActivityLatencyCritical)
+    //!        reason:reasonNSString];`
+    //! and retains the returned object until `end_activity`.
+    //!
+    //! This workstream ships the PowerAssertion RAII guard + wiring
+    //! so `commands/live.rs` and `commands/llm.rs` can adopt it today
+    //! (matters on macOS, no-op elsewhere). The actual `objc2` bridge
+    //! lands in a follow-up commit that can introduce `objc2` +
+    //! `objc2-foundation` without touching the rest of the workspace
+    //! in the same change.
+    //!
+    //! Until then, `begin_activity` returns Err; callers (`begin()`)
+    //! log a warning but keep running, so recording continues to work
+    //! as today — the gap is just the App-Nap protection, not the
+    //! recording itself.
+
+    pub struct ActivityHandle {
+        #[allow(dead_code)]
+        retained: *mut std::ffi::c_void,
+    }
+
+    // SAFETY: The pointer is opaque to Rust; Foundation manages its
+    // lifetime via retain/release. We never dereference it directly.
+    unsafe impl Send for ActivityHandle {}
+
+    pub fn begin_activity(_reason: &str) -> Result<ActivityHandle, String> {
+        Err("macOS App Nap bridge not yet wired — objc2 integration tracked for a follow-up".into())
+    }
+
+    pub fn end_activity(_handle: ActivityHandle) {}
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn power_assertion_is_a_no_op_drop() {
+        let guard = PowerAssertion::begin("test-reason");
+        drop(guard);
+    }
+
+    #[test]
+    fn multiple_assertions_get_unique_ids() {
+        let a = PowerAssertion::begin("a");
+        let b = PowerAssertion::begin("b");
+        assert_ne!(a.id, b.id);
+    }
+}

src-tauri/src/lib.rs

@@ -229,6 +229,11 @@ pub fn run() {
                 crate::commands::models::prewarm_default_model(whisper);
             }
 
+            // Runtime-warning banner: push CPU-feature + Vulkan-loader
+            // fallbacks to the frontend so Settings can render a one-line
+            // hint. No-ops on a fully-supported box.
+            crate::commands::models::emit_runtime_warnings(&app.handle());
+
             if let Err(e) = tray::setup(app) {
                 eprintln!("Failed to setup tray: {e}");
             }

src-tauri/tauri.conf.json

@@ -23,7 +23,7 @@
       }
     ],
     "security": {
-      "csp": "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' asset: https://asset.localhost; connect-src ipc: http://ipc.localhost asset: https://asset.localhost http://localhost:* ws://localhost:*; media-src 'self' asset: https://asset.localhost"
+      "csp": "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' asset: https://asset.localhost; connect-src ipc: http://ipc.localhost asset: https://asset.localhost http://localhost:* ws://localhost:* http://127.0.0.1:* ws://127.0.0.1:*; media-src 'self' asset: https://asset.localhost"
     }
   },
   "plugins": {